/**
Copyright: Copyright (c) 2018, Joakim Brännström. All rights reserved.
License: MPL-2
Author: Joakim Brännström (joakim.brannstrom@gmx.com)

This Source Code Form is subject to the terms of the Mozilla Public License,
v.2.0. If a copy of the MPL was not distributed with this file, You can obtain
one at http://mozilla.org/MPL/2.0/.

This module contains the schema to initialize the database.

To ensure that the upgrade path for a database always work a database is
created at the "lowest supported" and upgraded to the latest.

# How to add schema change

1. add an upgrade function, upgradeVX.

The function makeUpgradeTable will then automatically find it and use it. X
 **must** be the version upgrading FROM.

# Style
A database schema upgrade path shall have a comment stating what date it was added.
Each change to the database schema must have an equal upgrade added.

# Sqlite3
From the sqlite3 manual $(LINK https://www.sqlite.org/datatype3.html):
Each value stored in an SQLite database (or manipulated by the database
engine) has one of the following storage classes:

NULL. The value is a NULL value.

INTEGER. The value is a signed integer, stored in 1, 2, 3, 4, 6, or 8 bytes
depending on the magnitude of the value.

REAL. The value is a floating point value, stored as an 8-byte IEEE floating
point number.

TEXT. The value is a text string, stored using the database encoding (UTF-8,
UTF-16BE or UTF-16LE).

BLOB. The value is a blob of data, stored exactly as it was input.

A storage class is more general than a datatype. The INTEGER storage class, for
example, includes 6 different integer datatypes of different lengths.  This
makes a difference on disk. But as soon as INTEGER values are read off of disk
and into memory for processing, they are converted to the most general datatype
(8-byte signed integer). And so for the most part, "storage class" is
indistinguishable from "datatype" and the two terms can be used
interchangeably.

# ON DELETE CASCADE

when a ON DELETE CASCADE is added an index should be created too of the childs
foreign key.

From the sqlite documentation:

Indices are not required for child key columns but they are almost always
beneficial. […]

Each time an application deletes a row from the ... parent table, it performs
[a query] to search for referencing rows in the ... child table.

If this query returns any rows at all, then SQLite concludes that deleting the
row from the parent table would violate the foreign key constraint and returns
an error. Similar queries may be run if the content of the parent key is
modified or a new row is inserted into the parent table. If these queries
cannot use an index, they are forced to do a linear scan of the entire child
table. In a non-trivial database, this may be prohibitively expensive.

So, in most real systems, an index should be created on the child key columns
of each foreign key constraint. The child key index does not have to be (and
usually will not be) a UNIQUE index.

*/
module dextool.plugin.mutate.backend.database.schema;

import logger = std.experimental.logger;
import std.array : array, empty;
import std.datetime : SysTime, dur, Clock;
import std.exception : collectException;
import std.format : format;

import dextool.plugin.mutate.backend.type : Language;

import d2sqlite3 : SqlDatabase = Database;
import miniorm : Miniorm, TableName, buildSchema, ColumnParam, TableForeignKey, TableConstraint,
    TablePrimaryKey, KeyRef, KeyParam, ColumnName, delete_, insert, select, spinSql, silentLog;

immutable allTestCaseTable = "all_test_case";
immutable depFileTable = "dependency_file";
immutable depRootTable = "rel_dependency_root";
immutable dextoolVersionTable = "dextool_version";
immutable filesTable = "files";
immutable killedTestCaseTable = "killed_test_case";
immutable markedMutantTable = "marked_mutant";
immutable mutantTimeoutCtxTable = "mutant_timeout_ctx";
immutable mutantTimeoutWorklistTable = "mutant_timeout_worklist";
immutable mutantMemOverloadWorklistTable = "mutant_memoverload_worklist";
immutable mutantWorklistTable = "mutant_worklist";
immutable mutationPointTable = "mutation_point";
immutable mutationScoreHistoryTable = "mutation_score_history";
immutable mutationStatusTable = "mutation_status";
immutable mutationTable = "mutation";
immutable nomutDataTable = "nomut_data";
immutable nomutTable = "nomut";
immutable rawSrcMetadataTable = "raw_src_metadata";
immutable runtimeHistoryTable = "test_cmd_runtime_history";
immutable schemaMutantQTable = "schema_mutant_q";
immutable schemaSizeQTable = "schema_size_q";
immutable schemaVersionTable = "schema_version";
immutable schemataFragmentTable = "schemata_fragment";
immutable schemataMutantTable = "schemata_mutant";
immutable schemataTable = "schemata";
immutable schemataUsedTable = "schemata_used";
immutable srcCovInfoTable = "src_cov_info";
immutable srcCovTable = "src_cov_instr";
immutable srcCovTimeStampTable = "src_cov_timestamp";
immutable srcMetadataTable = "src_metadata";
immutable testCmdMutatedTable = "test_cmd_mutated";
immutable testCmdOriginalTable = "test_cmd_original";
immutable testFilesTable = "test_files";

private immutable invalidSchemataTable = "invalid_schemata";
private immutable schemataWorkListTable = "schemata_worklist";
private immutable testCaseTableV1 = "test_case";

/** Initialize or open an existing database.
 *
 * Params:
 *  p = path where to initialize a new database or open an existing
 *
 * Returns: an open sqlite3 database object.
 */
Miniorm initializeDB(const string p) @trusted
in {
    assert(p.length != 0);
}
do {
    import std.file : exists;
    import my.file : followSymlink;
    import my.optional;
    import my.path : Path;
    import d2sqlite3 : SQLITE_OPEN_CREATE, SQLITE_OPEN_READWRITE;

    static void setPragmas(ref SqlDatabase db) {
        // dfmt off
        auto pragmas = [
            // required for foreign keys with cascade to work
            "PRAGMA foreign_keys=ON;",
        ];
        // dfmt on

        foreach (p; pragmas) {
            db.run(p);
        }
    }

    const isOldDb = exists(followSymlink(Path(p)).orElse(Path(p)).toString);
    SqlDatabase sqliteDb;
    scope (success)
        setPragmas(sqliteDb);

    logger.trace("Opening database ", p);
    try {
        sqliteDb = SqlDatabase(p, SQLITE_OPEN_READWRITE);
    } catch (Exception e) {
        logger.trace(e.msg);
        logger.trace("Initializing a new sqlite3 database");
        sqliteDb = SqlDatabase(p, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE);
    }

    auto db = Miniorm(sqliteDb);

    auto tbl = makeUpgradeTable;
    const longTimeout = 10.dur!"minutes";
    try {
        if (isOldDb && spinSql!(() => getSchemaVersion(db),
                silentLog)(10.dur!"seconds") >= tbl.latestSchemaVersion)
            return db;
    } catch (Exception e) {
        logger.info("The database is probably locked. Will keep trying to open for ", longTimeout);
    }
    if (isOldDb && spinSql!(() => getSchemaVersion(db))(longTimeout) >= tbl.latestSchemaVersion)
        return db;

    // TODO: remove all key off in upgrade schemas.
    const giveUpAfter = Clock.currTime + longTimeout;
    bool failed = true;
    while (failed && Clock.currTime < giveUpAfter) {
        try {
            auto trans = db.transaction;
            db.run("PRAGMA foreign_keys=OFF;");
            upgrade(db, tbl);
            trans.commit;
            failed = false;
        } catch (Exception e) {
            logger.trace(e.msg);
        }
    }

    if (failed) {
        logger.error("Unable to upgrade the database to the latest schema");
        throw new Exception(null);
    }

    return db;
}

package:

// metadata about mutants that occur on a line extracted from the source code.
// It is intended to further refined.
// nomut = if the line should ignore mutants.
// tag = a user defined tag for a NOMUT.
// comment = a user defined comment.
@TableName(rawSrcMetadataTable)
@TableForeignKey("file_id", KeyRef("files(id)"), KeyParam("ON DELETE CASCADE"))
@TableConstraint("unique_line_in_file UNIQUE (file_id, line)")
struct RawSrcMetadata {
    long id;

    @ColumnName("file_id")
    long fileId;

    @ColumnParam("")
    uint line;

    @ColumnParam("")
    long nomut;

    @ColumnParam("")
    string tag;

    @ColumnParam("")
    string comment;
}

@TableName(srcMetadataTable)
@TableForeignKey("mut_id", KeyRef("mutation(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("st_id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("mp_id", KeyRef("mutation_point(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("file_id", KeyRef("files(id)"), KeyParam("ON DELETE CASCADE"))
struct SrcMetadataTable {
    @ColumnName("mut_id")
    long mutationId;

    @ColumnName("st_id")
    long mutationStatusId;

    @ColumnName("mp_id")
    long mutationPointId;

    @ColumnName("file_id")
    long fileId;

    @ColumnName("nomut")
    long nomutCount;
}

// Reconstruct the nomut table in Miniorm.
@TableName(nomutTable)
@TableForeignKey("mp_id", KeyRef("mutation_point(id)"), KeyParam("ON DELETE CASCADE"))
struct NomutTbl {
    @ColumnName("mp_id")
    long mutationPointId;

    long line;

    /// != 0 when a nomut is tagged on the line.
    long status;
}

@TableName(nomutDataTable)
@TableForeignKey("mut_id", KeyRef("mutation(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("mp_id", KeyRef("mutation_point(id)"), KeyParam("ON DELETE CASCADE"))
struct NomutDataTbl {
    @ColumnName("mut_id")
    long mutationId;

    @ColumnName("mp_id")
    long mutationPointId;

    long line;

    @ColumnParam("")
    string tag;

    @ColumnParam("")
    string comment;
}

@TableName(schemaVersionTable)
struct VersionTbl {
    @ColumnName("version")
    long version_;
}

@TableName(dextoolVersionTable)
struct DextoolVersionTable {
    /// checksum is 64bit.
    long checksum;
}

@TableName(filesTable)
@TableConstraint("unique_ UNIQUE (path)")
struct FilesTbl {
    long id;

    string path;

    // checksum of the file content, 128bit.
    long checksum0;
    long checksum1;
    Language lang;

    @ColumnName("timestamp")
    SysTime timeStamp;

    /// True if the file is a root.
    bool root;
}

@TableName(testFilesTable)
@TableConstraint("unique_ UNIQUE (path)")
struct TestFilesTable {
    long id;

    string path;

    /// checksum is 128bit.
    long checksum0;
    long checksum1;

    /// Last time a change to the test file where detected.
    @ColumnName("timestamp")
    SysTime timeStamp;
}

/// there shall never exist two mutations points for the same file+offset.
@TableName(mutationPointTable)
@TableConstraint("file_offset UNIQUE (file_id, offset_begin, offset_end)")
@TableForeignKey("file_id", KeyRef("files(id)"), KeyParam("ON DELETE CASCADE"))
struct MutationPointTbl {
    long id;
    long file_id;
    uint offset_begin;
    uint offset_end;

    /// line start from zero
    @ColumnParam("")
    uint line;
    @ColumnParam("")
    uint column;

    @ColumnParam("")
    uint line_end;

    @ColumnParam("")
    uint column_end;
}

@TableName(mutationTable)
@TableForeignKey("mp_id", KeyRef("mutation_point(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("st_id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
@TableConstraint("unique_ UNIQUE (mp_id, kind)")
struct MutationTbl {
    long id;

    long mp_id;

    @ColumnParam("")
    long st_id;

    long kind;
}

/**
 * This could use an intermediate adapter table to normalise the test_case data
 * but I chose not to do that because it makes it harder to add test cases and
 * do a cleanup.
 */
@TableName(killedTestCaseTable)
@TableForeignKey("st_id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("tc_id", KeyRef("all_test_case(id)"), KeyParam("ON DELETE CASCADE"))
@TableConstraint("unique_ UNIQUE (st_id, tc_id)")
struct TestCaseKilledTbl {
    long id;

    @ColumnName("st_id")
    long mutationStatusId;
    @ColumnName("tc_id")
    long testCaseId;

    // location is a filesystem location or other suitable helper for a user to
    // locate the test.
    @ColumnParam("")
    string location;
}

/**
 * Track all test cases that has been found by the test suite output analyzer.
 * Useful to find test cases that has never killed any mutant.
 * name should match test_case_killed_v2_tbl
 * TODO: name should be the primary key. on a conflict a counter should be updated.
 */
@TableName(allTestCaseTable)
@TableConstraint("unique_ UNIQUE (name)")
struct AllTestCaseTbl {
    long id;
    string name;

    @ColumnName("is_new")
    bool isNew;
}

/**
 * the status of a mutant. if it is killed or otherwise.
 * multiple mutation operators can result in the same change of the source
 * code. By coupling the mutant status to the checksum of the source code
 * change it means that two mutations that have the same checksum will
 * "cooperate".
 * TODO: change the checksum to being NOT NULL in the future. Can't for now
 * when migrating to schema version 5->6.
 * compile_time_ms = time it took to compile the program for the mutant
 * test_time_ms = time it took to run the test suite
 * updated_ts = is when the status where last updated. Seconds at UTC+0.
 * added_ts = when the mutant where added to the system. UTC+0.
 */
@TableName(mutationStatusTable)
@TableConstraint("checksum UNIQUE (checksum0, checksum1)")
struct MutationStatusTbl {
    long id;

    /// Mutation.Status
    long status;

    @ColumnName("exit_code")
    int exitCode;

    @ColumnName("compile_time_ms")
    long compileTimeMs;

    @ColumnName("test_time_ms")
    long testTimeMs;

    @ColumnParam("")
    @ColumnName("update_ts")
    SysTime updated;

    @ColumnParam("")
    @ColumnName("added_ts")
    SysTime added;

    long checksum0;
    long checksum1;

    /// Priority of the mutant used when testing.
    long prio;
}

/** Mutants that should be tested.
 */
@TableName(mutantWorklistTable)
@TableForeignKey("id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
struct MutantWorklistTbl {
    long id;
    long prio;
}

/** Memory overload mutants that are re-tested one extra time.
 */
@TableName(mutantMemOverloadWorklistTable)
@TableForeignKey("id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
struct MutantMemOverloadtWorklistTbl {
    long id;
}

/** Timeout mutants that are re-tested until none of them change status from
 * timeout.
 */
@TableName(mutantTimeoutWorklistTable)
@TableForeignKey("id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
struct MutantTimeoutWorklistTbl {
    long id;
    /// iterations that the mutant have been tested.
    long iter;
}

/** The defaults for the schema is the state that the state machine start in.
 *
 * This mean that if there are nothing in the database then `.init` is the correct starting point.
 */
@TableName(mutantTimeoutCtxTable)
struct MutantTimeoutCtxTbl {
    /// What iteration the timeout testing is at.
    long iter;

    /// Last count of the mutants in the worklist that where in the timeout state.
    long worklistCount;

    enum State {
        init_,
        running,
        done
    }

    /// State of the timeout algorithm.
    State state;
}

/** The lower 64bit of the checksum should be good enough as the primary key.
 * By doing it this way it is easier to update a marked mutant without
 * "peeking" in the database ("insert or update").
 *
 * Both `st_id` and `mut_id` are values that sqlite can reuse between analyzes
 * if they have been previously removed thus the only assured connection
 * between a marked mutant and future code changes is the checksum.
 */
@TableName(markedMutantTable)
@TablePrimaryKey("checksum0")
struct MarkedMutantTbl {
    /// Checksum of the mutant status the marking is related to.
    long checksum0;
    long checksum1;

    /// updated each analyze.
    @ColumnName("st_id")
    long mutationStatusId;

    /// updated each analyze.
    @ColumnName("mut_id")
    long mutationId;

    uint line;
    uint column;
    string path;

    /// The status it should always be changed to.
    long toStatus;

    /// Time when the mutant where marked.
    SysTime time;

    string rationale;

    string mutText;
}

@TableName(schemataMutantTable)
@TableForeignKey("st_id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("schem_id", KeyRef("schemata(id)"), KeyParam("ON DELETE CASCADE"))
@TableConstraint("unique_ UNIQUE (st_id, schem_id)")
struct SchemataMutantTable {
    @ColumnName("st_id")
    long statusId;
    @ColumnName("schem_id")
    long schemaId;
}

@TableName(schemataTable)
struct SchemataTable {
    long id;

    // number of fragments the schemata consist of.
    // used to detect if a fragment has been removed because its related file
    // was changed.
    long fragments;
}

@TableName(schemataUsedTable)
@TableForeignKey("id", KeyRef("schemata(id)"), KeyParam("ON DELETE CASCADE"))
struct SchemataUsedTable {
    import dextool.plugin.mutate.backend.database.type : SchemaStatus;

    long id;

    SchemaStatus status;
}

@TableName(schemataFragmentTable)
@TableForeignKey("schem_id", KeyRef("schemata(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("file_id", KeyRef("files(id)"), KeyParam("ON DELETE CASCADE"))
struct SchemataFragmentTable {
    long id;

    @ColumnName("schem_id")
    long schemataId;

    @ColumnName("file_id")
    long fileId;

    @ColumnName("order_")
    long order;

    @ColumnParam("")
    const(ubyte)[] text;

    @ColumnName("offset_begin")
    uint offsetBegin;
    @ColumnName("offset_end")
    uint offsetEnd;
}

@TableName(schemaMutantQTable)
@TableConstraint("unique_ UNIQUE (kind, path)")
struct SchemaMutantKindQTable {
    long id;

    /// mutant subtype
    long kind;

    // max 100
    long probability;

    // 64 bit checksum of the path
    long path;
}

@TableName(schemaSizeQTable)
struct SchemaSizeQTable {
    long id;
    long size;
}

/** The runtime of the test commands.
 *
 * By storing the data it reduces the need to run the test suite multiple times
 * to get the minimum.
 */
@TableName(runtimeHistoryTable)
struct RuntimeHistoryTable {
    long id;

    /// when the measurement was taken.
    @ColumnName("time")
    SysTime timeStamp;

    @ColumnName("time_ms")
    long timeMs;
}

@TableName(mutationScoreHistoryTable)
struct MutationScoreHistoryTable {
    long id;

    /// when the measurement was taken.
    @ColumnName("time")
    SysTime timeStamp;

    double score;
}

/** All functions that has been discovered in the source code.
 * The `offset_begin` is where instrumentation points can be injected.
 */
@TableName(srcCovTable)
@TableForeignKey("file_id", KeyRef("files(id)"), KeyParam("ON DELETE CASCADE"))
@TableConstraint("file_offset UNIQUE (file_id, begin, end)")
struct CoverageCodeRegionTable {
    long id;

    @ColumnName("file_id")
    long fileId;

    /// the region in the files, in bytes.
    uint begin;
    uint end;
}

/** Each coverage region that has a valid status has an entry in this table.
 * It do mean that there can be region that do not exist in this table. That
 * mean that something went wrong when gathering the data.
 */
@TableName(srcCovInfoTable)
@TableForeignKey("id", KeyRef("src_cov_info(id)"), KeyParam("ON DELETE CASCADE"))
struct CoverageInfoTable {
    long id;

    /// True if the region has been visited.
    bool status;
}

/// When the coverage information was gathered.
@TableName(srcCovTimeStampTable)
struct CoverageTimeTtampTable {
    long id;

    @ColumnName("timestamp")
    SysTime timeStamp;
}

/** Files that roots are dependent on. They do not need to contain mutants.
 */
@TableName(depFileTable)
@TableConstraint("unique_ UNIQUE (file)")
struct DependencyFileTable {
    long id;

    string file;

    /// checksum is 128bit.
    long checksum0;
    long checksum1;
}

@TableName(depRootTable)
@TableForeignKey("dep_id", KeyRef("dependency_file(id)"), KeyParam("ON DELETE CASCADE"))
@TableForeignKey("file_id", KeyRef("files(id)"), KeyParam("ON DELETE CASCADE"))
@TableConstraint("unique_ UNIQUE (dep_id, file_id)")
struct DependencyRootTable {
    @ColumnName("dep_id")
    long depFileId;

    @ColumnName("file_id")
    long fileId;
}

@TableName(testCmdOriginalTable)
@TablePrimaryKey("checksum")
@TableConstraint("unique_ UNIQUE (cmd)")
struct TestCmdOriginalTable {
    long checksum;
    string cmd;
}

@TableName(testCmdMutatedTable)
@TablePrimaryKey("checksum")
struct TestCmdMutatedTable {
    long checksum;

    /// Mutation.Status
    long status;

    /// when the measurement was taken.
    @ColumnName("timestamp")
    SysTime timeStamp;
}

void updateSchemaVersion(ref Miniorm db, long ver) nothrow {
    try {
        db.run(delete_!VersionTbl);
        db.run(insert!VersionTbl.insert, VersionTbl(ver));
    } catch (Exception e) {
        logger.error(e.msg).collectException;
    }
}

long getSchemaVersion(ref Miniorm db) {
    auto v = db.run(select!VersionTbl);
    return v.empty ? 0 : v.front.version_;
}

void upgrade(ref Miniorm db, UpgradeTable tbl) {
    import d2sqlite3;

    immutable maxIndex = 30;

    alias upgradeFunc = void function(ref Miniorm db);

    bool hasUpdated;

    bool running = true;
    while (running) {
        const version_ = () {
            // first time the version table do not exist thus fail.
            try {
                return getSchemaVersion(db);
            } catch (Exception e) {
            }
            return 0;
        }();

        if (version_ >= tbl.latestSchemaVersion) {
            running = false;
            break;
        }

        logger.infof("Upgrading database from %s", version_).collectException;

        if (!hasUpdated)
            try {
                // only do this once and always before any changes to the database.
                foreach (i; 0 .. maxIndex) {
                    db.run(format!"DROP INDEX IF EXISTS i%s"(i));
                }
            } catch (Exception e) {
                logger.warning(e.msg).collectException;
                logger.warning("Unable to drop database indexes").collectException;
            }

        if (auto f = version_ in tbl) {
            try {
                hasUpdated = true;

                (*f)(db);
                if (version_ != 0)
                    updateSchemaVersion(db, version_ + 1);
            } catch (Exception e) {
                logger.trace(e).collectException;
                logger.error(e.msg).collectException;
                logger.warningf("Unable to upgrade a database of version %s",
                        version_).collectException;
                logger.warning("This might impact the functionality. It is unwise to continue")
                    .collectException;
                throw e;
            }
        } else {
            logger.info("Upgrade successful").collectException;
            running = false;
        }
    }

    // add indexes assuming the lastest database schema
    if (hasUpdated)
        try {
            int i;
            db.run(format!"CREATE INDEX i%s ON %s(path)"(i++, filesTable));
            db.run(format!"CREATE INDEX i%s ON %s(path)"(i++, testFilesTable));

            // improve getTestCaseMutantKills by 10x
            db.run(format!"CREATE INDEX i%s ON %s(tc_id,st_id)"(i++, killedTestCaseTable));
            db.run(format!"CREATE INDEX i%s ON %s(st_id)"(i++, mutationTable));

            // all on delete cascade
            db.run(format!"CREATE INDEX i%s ON %s(file_id)"(i++, rawSrcMetadataTable));
            db.run(format!"CREATE INDEX i%s ON %s(mut_id)"(i++, srcMetadataTable));
            db.run(format!"CREATE INDEX i%s ON %s(st_id)"(i++, srcMetadataTable));
            db.run(format!"CREATE INDEX i%s ON %s(mp_id)"(i++, srcMetadataTable));
            db.run(format!"CREATE INDEX i%s ON %s(file_id)"(i++, srcMetadataTable));
            db.run(format!"CREATE INDEX i%s ON %s(mp_id)"(i++, nomutTable));
            db.run(format!"CREATE INDEX i%s ON %s(mut_id)"(i++, nomutDataTable));
            db.run(format!"CREATE INDEX i%s ON %s(mp_id)"(i++, nomutDataTable));
            db.run(format!"CREATE INDEX i%s ON %s(file_id)"(i++, mutationPointTable));
            db.run(format!"CREATE INDEX i%s ON %s(mp_id)"(i++, mutationTable));
            db.run(format!"CREATE INDEX i%s ON %s(st_id)"(i++, mutationTable));
            db.run(format!"CREATE INDEX i%s ON %s(st_id)"(i++, killedTestCaseTable));
            db.run(format!"CREATE INDEX i%s ON %s(tc_id)"(i++, killedTestCaseTable));
            db.run(format!"CREATE INDEX i%s ON %s(st_id)"(i++, schemataMutantTable));
            db.run(format!"CREATE INDEX i%s ON %s(schem_id)"(i++, schemataMutantTable));
            db.run(format!"CREATE INDEX i%s ON %s(schem_id)"(i++, schemataFragmentTable));
            db.run(format!"CREATE INDEX i%s ON %s(file_id)"(i++, schemataFragmentTable));
            db.run(format!"CREATE INDEX i%s ON %s(file_id)"(i++, srcCovTable));
            db.run(format!"CREATE INDEX i%s ON %s(dep_id)"(i++, depRootTable));
            db.run(format!"CREATE INDEX i%s ON %s(file_id)"(i++, depRootTable));

            assert(i <= maxIndex);
        } catch (Exception e) {
            logger.warning(e.msg).collectException;
            logger.warning("Unable to create database indexes").collectException;
        }
}

/** If the database start it version 0, not initialized, then initialize to the
 * latest schema version.
 */
void upgradeV0(ref Miniorm db) {
    auto tbl = makeUpgradeTable;

    db.run(buildSchema!(VersionTbl, RawSrcMetadata, FilesTbl,
            MutationPointTbl, MutationTbl, TestCaseKilledTbl, AllTestCaseTbl,
            MutationStatusTbl, MutantTimeoutCtxTbl, MutantTimeoutWorklistTbl,
            MarkedMutantTbl, SrcMetadataTable, NomutTbl, NomutDataTbl,
            NomutDataTbl, SchemataTable, SchemataFragmentTable,
            SchemataMutantTable,
            SchemataUsedTable, SchemaMutantKindQTable, SchemaSizeQTable,
            MutantWorklistTbl, RuntimeHistoryTable, MutationScoreHistoryTable,
            TestFilesTable, CoverageCodeRegionTable,
            CoverageInfoTable, CoverageTimeTtampTable, DependencyFileTable,
            DependencyRootTable,
            DextoolVersionTable, TestCmdOriginalTable, TestCmdMutatedTable,
            MutantMemOverloadtWorklistTbl));

    updateSchemaVersion(db, tbl.latestSchemaVersion);
}

/// 2018-04-08
void upgradeV1(ref Miniorm db) {
    @TableName(allTestCaseTable)
    struct AllTestCaseTbl {
        long id;

        @ColumnParam("")
        string name;
    }

    @TableName(testCaseTableV1)
    @TableForeignKey("mut_id", KeyRef("mutation(id)"), KeyParam("ON DELETE CASCADE"))
    static struct TestCaseKilledTblV1 {
        ulong id;

        @ColumnName("mut_id")
        ulong mutantId;

        /// test_case is whatever identifier the user choose.
        @ColumnName("test_case")
        string testCase;
    }

    db.run(buildSchema!(TestCaseKilledTblV1, AllTestCaseTbl));
}

/// 2018-04-22
void upgradeV2(ref Miniorm db) {
    @TableName(filesTable)
    static struct FilesTbl {
        ulong id;

        @ColumnParam("")
        string path;

        ulong checksum0;
        ulong checksum1;
        Language lang;
    }

    immutable newTbl = "new_" ~ filesTable;

    db.run(buildSchema!FilesTbl("new_"));
    db.run(format("INSERT INTO %s (id,path,checksum0,checksum1) SELECT * FROM %s",
            newTbl, filesTable));
    db.replaceTbl(newTbl, filesTable);
}

/// 2018-09-01
void upgradeV3(ref Miniorm db) {
    @TableName(killedTestCaseTable)
    @TableForeignKey("mut_id", KeyRef("mutation(id)"), KeyParam("ON DELETE CASCADE"))
    struct TestCaseKilledTblV2 {
        ulong id;

        @ColumnName("mut_id")
        ulong mutantId;

        @ColumnParam("")
        string name;

        // location is a filesystem location or other suitable helper for a user to
        // locate the test.
        @ColumnParam("")
        string location;
    }

    db.run(buildSchema!TestCaseKilledTblV2);
    db.run(format("INSERT INTO %s (id,mut_id,name) SELECT * FROM %s",
            killedTestCaseTable, testCaseTableV1));
    db.run(format("DROP TABLE %s", testCaseTableV1));

    db.run(buildSchema!AllTestCaseTbl);
}

/// 2018-09-24
void upgradeV4(ref Miniorm db) {
    @TableName(killedTestCaseTable)
    @TableForeignKey("mut_id", KeyRef("mutation(id)"), KeyParam("ON DELETE CASCADE"))
    @TableForeignKey("tc_id", KeyRef("all_test_case(id)"), KeyParam("ON DELETE CASCADE"))
    static struct TestCaseKilledTblV3 {
        ulong id;

        @ColumnName("mut_id")
        ulong mutantId;
        @ColumnName("tc_id")
        ulong testCaseId;

        // location is a filesystem location or other suitable helper for a user to
        // locate the test.
        @ColumnParam("")
        string location;
    }

    immutable newTbl = "new_" ~ killedTestCaseTable;

    db.run(buildSchema!TestCaseKilledTblV3("new_"));

    // add all missing test cases to all_test_case
    db.run(format("INSERT INTO %s (name) SELECT DISTINCT t1.name FROM %s t1 LEFT JOIN %s t2 ON t2.name = t1.name WHERE t2.name IS NULL",
            allTestCaseTable, killedTestCaseTable, allTestCaseTable));
    // https://stackoverflow.com/questions/2686254/how-to-select-all-records-from-one-table-that-do-not-exist-in-another-table
    //Q: What is happening here?
    //
    //A: Conceptually, we select all rows from table1 and for each row we
    //attempt to find a row in table2 with the same value for the name column.
    //If there is no such row, we just leave the table2 portion of our result
    //empty for that row. Then we constrain our selection by picking only those
    //rows in the result where the matching row does not exist. Finally, We
    //ignore all fields from our result except for the name column (the one we
    //are sure that exists, from table1).
    //
    //While it may not be the most performant method possible in all cases, it
    //should work in basically every database engine ever that attempts to
    //implement ANSI 92 SQL

    // This do NOT WORK. The result is that that this upgrade is broken because
    // it drops all maps between killed_test_case and mutation.
    //db.run(format("INSERT INTO %s (id,mut_id,tc_id,location) SELECT t1.id,t1.mut_id,t2.id,t1.location FROM %s t1 INNER JOIN %s t2 ON t1.name = t2.name",
    //        newTbl, killedTestCaseTable, allTestCaseTable));

    db.replaceTbl(newTbl, killedTestCaseTable);
}

/** 2018-09-30
 *
 * This upgrade will drop all existing mutations and thus all results.
 * It is too complex trying to upgrade and keep the results.
 *
 * When removing this function also remove the status field in mutation_v2_tbl.
 */
void upgradeV5(ref Miniorm db) {
    @TableName(filesTable)
    @TableConstraint("unique_ UNIQUE (path)")
    struct FilesTbl {
        long id;

        @ColumnParam("")
        string path;

        /// checksum is 128bit.
        long checksum0;
        long checksum1;
        Language lang;
    }

    @TableName(mutationTable)
    @TableForeignKey("mp_id", KeyRef("mutation_point(id)"), KeyParam("ON DELETE CASCADE"))
    @TableForeignKey("st_id", KeyRef("mutation_status(id)"))
    @TableConstraint("unique_ UNIQUE (mp_id, kind)")
    static struct MutationTbl {
        ulong id;

        ulong mp_id;

        @ColumnParam("")
        ulong st_id;

        ulong kind;

        @ColumnParam("")
        ulong status;

        /// time in ms spent on verifying the mutant
        @ColumnParam("")
        ulong time;
    }

    @TableName(mutationStatusTable)
    @TableConstraint("checksum UNIQUE (checksum0, checksum1)")
    static struct MutationStatusTbl {
        ulong id;
        ulong status;
        ulong checksum0;
        ulong checksum1;
    }

    immutable new_mut_tbl = "new_" ~ mutationTable;
    db.run(buildSchema!MutationStatusTbl);

    db.run(format("DROP TABLE %s", mutationTable));
    db.run(buildSchema!MutationTbl);

    immutable newFilesTbl = "new_" ~ filesTable;
    db.run(buildSchema!FilesTbl("new_"));
    db.run(format("INSERT OR IGNORE INTO %s (id,path,checksum0,checksum1,lang) SELECT * FROM %s",
            newFilesTbl, filesTable));
    db.replaceTbl(newFilesTbl, filesTable);
}

/// 2018-10-11
void upgradeV6(ref Miniorm db) {
    @TableName(mutationStatusTable)
    @TableConstraint("checksum UNIQUE (checksum0, checksum1)")
    static struct MutationStatusTbl {
        ulong id;
        ulong status;
        ulong time;
        SysTime timestamp;
        ulong checksum0;
        ulong checksum1;
    }

    @TableName(mutationTable)
    @TableForeignKey("mp_id", KeyRef("mutation_point(id)"), KeyParam("ON DELETE CASCADE"))
    @TableForeignKey("st_id", KeyRef("mutation_status(id)"))
    @TableConstraint("unique_ UNIQUE (mp_id, kind)")
    struct MutationTbl {
        long id;

        long mp_id;

        @ColumnParam("")
        long st_id;

        long kind;
    }

    immutable new_mut_tbl = "new_" ~ mutationTable;

    db.run(buildSchema!MutationTbl("new_"));

    db.run(format("INSERT INTO %s (id,mp_id,st_id,kind) SELECT id,mp_id,st_id,kind FROM %s",
            new_mut_tbl, mutationTable));
    db.replaceTbl(new_mut_tbl, mutationTable);

    immutable new_muts_tbl = "new_" ~ mutationStatusTable;
    db.run(buildSchema!MutationStatusTbl("new_"));
    db.run(format("INSERT INTO %s (id,status,checksum0,checksum1) SELECT id,status,checksum0,checksum1 FROM %s",
            new_muts_tbl, mutationStatusTable));
    db.replaceTbl(new_muts_tbl, mutationStatusTable);
}

/// 2018-10-15
void upgradeV7(ref Miniorm db) {
    @TableName(killedTestCaseTable)
    @TableForeignKey("st_id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
    @TableForeignKey("tc_id", KeyRef("all_test_case(id)"), KeyParam("ON DELETE CASCADE"))
    struct TestCaseKilledTbl {
        long id;

        @ColumnName("st_id")
        long mutationStatusId;
        @ColumnName("tc_id")
        long testCaseId;

        // location is a filesystem location or other suitable helper for a user to
        // locate the test.
        @ColumnParam("")
        string location;
    }

    immutable newTbl = "new_" ~ killedTestCaseTable;

    db.run(buildSchema!TestCaseKilledTbl("new_"));

    db.run(format("INSERT INTO %s (id,st_id,tc_id,location)
        SELECT t0.id,t1.st_id,t0.tc_id,t0.location
        FROM %s t0, %s t1
        WHERE
        t0.mut_id = t1.id", newTbl,
            killedTestCaseTable, mutationTable));

    db.replaceTbl(newTbl, killedTestCaseTable);
}

/// 2018-10-20
void upgradeV8(ref Miniorm db) {
    immutable newTbl = "new_" ~ mutationPointTable;
    db.run(buildSchema!MutationPointTbl("new_"));
    db.run(format("INSERT INTO %s (id,file_id,offset_begin,offset_end,line,column)
        SELECT t0.id,t0.file_id,t0.offset_begin,t0.offset_end,t0.line,t0.column
        FROM %s t0",
            newTbl, mutationPointTable));

    db.replaceTbl(newTbl, mutationPointTable);
}

/// 2018-11-10
void upgradeV9(ref Miniorm db) {
    @TableName(mutationStatusTable)
    @TableConstraint("checksum UNIQUE (checksum0, checksum1)")
    struct MutationStatusTbl {
        long id;
        long status;

        @ColumnParam("")
        long time;

        @ColumnName("test_cnt")
        long testCnt;

        @ColumnParam("")
        @ColumnName("update_ts")
        SysTime updated;

        @ColumnParam("")
        @ColumnName("added_ts")
        SysTime added;

        long checksum0;
        long checksum1;
    }

    immutable newTbl = "new_" ~ mutationStatusTable;
    db.run(buildSchema!MutationStatusTbl("new_"));
    db.run(format("INSERT INTO %s (id,status,time,test_cnt,update_ts,checksum0,checksum1)
        SELECT t0.id,t0.status,t0.time,0,t0.timestamp,t0.checksum0,t0.checksum1
        FROM %s t0",
            newTbl, mutationStatusTable));

    replaceTbl(db, newTbl, mutationStatusTable);
}

/// 2018-11-25
void upgradeV10(ref Miniorm db) {
    @TableName(rawSrcMetadataTable)
    @TableForeignKey("file_id", KeyRef("files(id)"), KeyParam("ON DELETE CASCADE"))
    @TableConstraint("unique_line_in_file UNIQUE (file_id, line)")
    struct RawSrcMetadata {
        ulong id;

        @ColumnName("file_id")
        ulong fileId;

        @ColumnParam("")
        uint line;

        @ColumnParam("")
        ulong nomut;
    }

    db.run(buildSchema!RawSrcMetadata);
    void makeSrcMetadataView(ref Miniorm db) {
        // check if a NOMUT is on or between the start and end of a mutant.
        immutable src_metadata_v1_tbl = "CREATE VIEW %s
            AS
            SELECT
            t0.id AS mut_id,
            t1.id AS st_id,
            t2.id AS mp_id,
            t3.id AS file_id,
            (SELECT count(*) FROM %s in_t0, %s in_t1
             WHERE
             in_t0.file_id = in_t1.file_id AND
             t0.mp_id = in_t0.id AND
             (in_t1.line BETWEEN in_t0.line AND in_t0.line_end)) AS nomut
                FROM %s t0, %s t1, %s t2, %s t3
                WHERE
                t0.mp_id = t2.id AND
                t0.st_id = t1.id AND
                t2.file_id = t3.id
                ";

        db.run(format(src_metadata_v1_tbl, srcMetadataTable, mutationPointTable, rawSrcMetadataTable,
                mutationTable, mutationStatusTable, mutationPointTable, filesTable));
    }

    makeSrcMetadataView(db);
}

/// 2019-04-06
void upgradeV11(ref Miniorm db) {
    immutable newTbl = "new_" ~ rawSrcMetadataTable;
    db.run(buildSchema!RawSrcMetadata("new_"));
    db.run(format!"INSERT INTO %s (id,file_id,line,nomut) SELECT t.id,t.file_id,t.line,t.nomut FROM %s t"(newTbl,
            rawSrcMetadataTable));
    replaceTbl(db, newTbl, rawSrcMetadataTable);

    db.run(format("DROP VIEW %s", srcMetadataTable)).collectException;

    // Associate metadata from lines with the mutation status.
    void makeSrcMetadataView(ref Miniorm db) {
        // check if a NOMUT is on or between the start and end of a mutant.
        immutable src_metadata_tbl = "CREATE VIEW %s
        AS
        SELECT DISTINCT
        t0.id AS mut_id,
        t1.id AS st_id,
        t2.id AS mp_id,
        t3.id AS file_id,
        (SELECT count(*) FROM %s WHERE nomut.mp_id = t2.id) as nomut
        FROM %s t0, %s t1, %s t2, %s t3
        WHERE
        t0.mp_id = t2.id AND
        t0.st_id = t1.id AND
        t2.file_id = t3.id";
        db.run(format(src_metadata_tbl, srcMetadataTable, nomutTable,
                mutationTable, mutationStatusTable, mutationPointTable, filesTable));

        immutable nomut_tbl = "CREATE VIEW %s
        AS
        SELECT
        t0.id mp_id,
        t1.line line,
        count(*) status
        FROM %s t0, %s t1
        WHERE
        t0.file_id = t1.file_id AND
        (t1.line BETWEEN t0.line AND t0.line_end)
        GROUP BY
        t0.id";
        db.run(format(nomut_tbl, nomutTable, mutationPointTable, rawSrcMetadataTable));

        immutable nomut_data_tbl = "CREATE VIEW %s
        AS
        SELECT
        t0.id as mut_id,
        t0.mp_id as mp_id,
        t1.line as line,
        t1.tag as tag,
        t1.comment as comment
        FROM %s t0, %s t1, %s t2
        WHERE
        t0.mp_id = t2.mp_id AND
        t1.line = t2.line";
        db.run(format(nomut_data_tbl, nomutDataTable, mutationTable,
                rawSrcMetadataTable, nomutTable));
    }

    makeSrcMetadataView(db);
}

/// 2019-08-28
void upgradeV12(ref Miniorm db) {
    /** Timeout mutants that are re-tested until none of them change status from
     * timeout.
     */
    @TableName(mutantTimeoutWorklistTable)
    @TableForeignKey("id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
    struct MutantTimeoutWorklistTbl {
        long id;
    }

    db.run(buildSchema!(MutantTimeoutCtxTbl, MutantTimeoutWorklistTbl));
}

/// 2019-11-12
void upgradeV13(ref Miniorm db) {
    @TableName(markedMutantTable)
    @TablePrimaryKey("st_id")
    struct MarkedMutantTbl {
        @ColumnName("st_id")
        long mutationStatusId;

        @ColumnName("mut_id")
        long mutationId;

        uint line;

        uint column;

        string path;

        @ColumnName("to_status")
        ulong toStatus;

        SysTime time;

        string rationale;

        @ColumnName("mut_text")
        string mutText;
    }

    db.run(buildSchema!(MarkedMutantTbl));
}

/// 2020-01-12
void upgradeV14(ref Miniorm db) {
    db.run(format!"DROP VIEW %s"(srcMetadataTable));
    db.run(format!"DROP VIEW %s"(nomutTable));
    db.run(format!"DROP VIEW %s"(nomutDataTable));

    db.run(buildSchema!(SrcMetadataTable, NomutTbl, NomutDataTbl));
    logger.info("Re-execute analyze to update the NOMUT data");
}

/// 2020-01-21
void upgradeV15(ref Miniorm db) {
    // fix bug in the marked mutant table
    db.run(format!"DROP TABLE %s"(markedMutantTable));
    db.run(buildSchema!MarkedMutantTbl);
    logger.info("Dropping all marked mutants because of database changes");
}

/// 2020-02-12
void upgradeV16(ref Miniorm db) {
    @TableName(schemataWorkListTable)
    @TableForeignKey("id", KeyRef("schemata(id)"), KeyParam("ON DELETE CASCADE"))
    static struct SchemataWorkListTable {
        long id;
    }

    @TableName(schemataMutantTable)
    @TableForeignKey("st_id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
    @TableForeignKey("schem_id", KeyRef("schemata_fragment(id)"), KeyParam("ON DELETE CASCADE"))
    static struct SchemataMutantTable {
        @ColumnName("st_id")
        long statusId;
        @ColumnName("schem_id")
        long schemaId;
    }

    db.run(buildSchema!(SchemataFragmentTable, SchemataWorkListTable, SchemataMutantTable));
}

/// 2020-02-12
void upgradeV17(ref Miniorm db) {
    @TableName(schemataTable)
    static struct SchemataTable {
        long id;
    }

    db.run(buildSchema!(SchemataTable));
}

/// 2020-03-21
void upgradeV18(ref Miniorm db) {
    // this force an old database to add indexes
}

/// 2020-04-01
void upgradeV19(ref Miniorm db) {
    db.run("DROP TABLE " ~ schemataWorkListTable);
    db.run("DROP TABLE " ~ schemataTable);
    db.run("DROP TABLE " ~ schemataMutantTable);

    @TableName(invalidSchemataTable)
    @TableForeignKey("id", KeyRef("schemata(id)"), KeyParam("ON DELETE CASCADE"))
    struct InvalidSchemataTable {
        long id;
    }

    @TableName(schemataTable)
    struct SchemataTable {
        long id;

        // number of fragments the schemata consist of.
        // used to detect if a fragment has been removed because its related file
        // was changed.
        long fragments;

        // runtime generated constant that make it possible to "prune" old
        // schematas automatically. it assumes that each new version of dextool may
        // contain updates to the schematas thus the old schemats should be
        // removed.
        @ColumnName("version")
        long version_;
    }

    db.run(buildSchema!(SchemataTable, SchemataMutantTable, InvalidSchemataTable));
}

/// 2020-06-01
void upgradeV20(ref Miniorm db) {
    db.run("DROP TABLE " ~ schemataMutantTable);
    db.run(buildSchema!(SchemataMutantTable));
}

/// 2020-11-28
void upgradeV21(ref Miniorm db) {
    @TableName(schemataUsedTable)
    @TableForeignKey("id", KeyRef("schemata(id)"), KeyParam("ON DELETE CASCADE"))
    struct SchemataUsedTable {
        long id;
    }

    db.run("DROP TABLE " ~ invalidSchemataTable);
    db.run(buildSchema!(SchemataUsedTable));
}

/// 2020-11-28
void upgradeV22(ref Miniorm db) {
    @TableName(mutantWorklistTable)
    @TableForeignKey("id", KeyRef("mutation_status(id)"), KeyParam("ON DELETE CASCADE"))
    struct MutantWorklistTbl {
        long id;
    }

    db.run(buildSchema!(MutantWorklistTbl));
}

/// 2020-12-06
void upgradeV23(ref Miniorm db) {
    db.run(buildSchema!(RuntimeHistoryTable));
}

/// 2020-12-06
void upgradeV24(ref Miniorm db) {
    db.run(buildSchema!(MutationScoreHistoryTable));
}

/// 2020-12-25
void upgradeV25(ref Miniorm db) {
    import std.traits : EnumMembers;
    import dextool.plugin.mutate.backend.type : Mutation;

    @TableName(mutationStatusTable)
    @TableConstraint("checksum UNIQUE (checksum0, checksum1)")
    struct MutationStatusTbl {
        long id;
        long status;
        @ColumnName("exit_code")
        int exitCode;

        @ColumnParam("")
        long time;

        @ColumnName("test_cnt")
        long testCnt;

        @ColumnParam("")
        @ColumnName("update_ts")
        SysTime updated;

        @ColumnParam("")
        @ColumnName("added_ts")
        SysTime added;

        long checksum0;
        long checksum1;
    }

    immutable newTbl = "new_" ~ mutationStatusTable;
    db.run(buildSchema!MutationStatusTbl("new_"));

    auto stmt = db.prepare(format(
            "INSERT INTO %s (id,status,exit_code,time,test_cnt,update_ts,added_ts,checksum0,checksum1)
        SELECT t.id,t.status,:ecode,t.time,t.test_cnt,t.update_ts,t.added_ts,t.checksum0,t.checksum1
        FROM %s t WHERE t.status = :status",
            newTbl, mutationStatusTable));

    foreach (st; [EnumMembers!(Mutation.Status)]) {
        stmt.get.bind(":ecode", (st == Mutation.Status.killed) ? 1 : 0);
        stmt.get.bind(":status", cast(long) st);
        stmt.get.execute;
        stmt.get.reset;
    }

    replaceTbl(db, newTbl, mutationStatusTable);
}

/// 2020-12-25
void upgradeV26(ref Miniorm db) {
    immutable newTbl = "new_" ~ killedTestCaseTable;
    db.run(buildSchema!TestCaseKilledTbl("new_"));

    db.run(format("INSERT OR IGNORE INTO %s (id, st_id, tc_id, location)
        SELECT t.id, t.st_id, t.tc_id, t.location
        FROM %s t",
            newTbl, killedTestCaseTable));
    replaceTbl(db, newTbl, killedTestCaseTable);
}

/// 2020-12-25
void upgradeV27(ref Miniorm db) {
    @TableName(allTestCaseTable)
    @TableConstraint("unique_ UNIQUE (name)")
    struct AllTestCaseTbl {
        long id;
        string name;
    }

    immutable newTbl = "new_" ~ allTestCaseTable;
    db.run(buildSchema!AllTestCaseTbl("new_"));

    db.run(format("INSERT OR IGNORE INTO %s (id, name)
        SELECT t.id, t.name
        FROM %s t", newTbl, allTestCaseTable));
    replaceTbl(db, newTbl, allTestCaseTable);
}

/// 2020-12-25
void upgradeV28(ref Miniorm db) {
    import dextool.plugin.mutate.backend.type : Mutation;

    @TableName(mutationStatusTable)
    @TableConstraint("checksum UNIQUE (checksum0, checksum1)")
    struct MutationStatusTbl {
        long id;
        long status;
        @ColumnName("exit_code")
        int exitCode;

        @ColumnName("compile_time_ms")
        long compileTimeMs;

        @ColumnName("test_time_ms")
        long testTimeMs;

        @ColumnName("test_cnt")
        long testCnt;

        @ColumnParam("")
        @ColumnName("update_ts")
        SysTime updated;

        @ColumnParam("")
        @ColumnName("added_ts")
        SysTime added;

        long checksum0;
        long checksum1;
    }

    immutable newTbl = "new_" ~ mutationStatusTable;
    db.run(buildSchema!MutationStatusTbl("new_"));

    db.run(format("INSERT INTO %s (id,status,exit_code,compile_time_ms,test_time_ms,test_cnt,update_ts,added_ts,checksum0,checksum1)
        SELECT t.id,t.status,t.exit_code,0,t.time,t.test_cnt,t.update_ts,t.added_ts,t.checksum0,t.checksum1
        FROM %s t WHERE t.time NOT NULL", newTbl, mutationStatusTable));

    db.run(format("INSERT INTO %s (id,status,exit_code,compile_time_ms,test_time_ms,test_cnt,update_ts,added_ts,checksum0,checksum1)
        SELECT t.id,t.status,t.exit_code,0,0,t.test_cnt,t.update_ts,t.added_ts,t.checksum0,t.checksum1
        FROM %s t WHERE t.time IS NULL", newTbl, mutationStatusTable));

    replaceTbl(db, newTbl, mutationStatusTable);
}

/// 2020-12-27
void upgradeV29(ref Miniorm db) {
    db.run(buildSchema!(TestFilesTable));
}

/// 2020-12-29
void upgradeV30(ref Miniorm db) {
    import std.datetime : Clock;
    import miniorm : toSqliteDateTime;

    @TableName(filesTable)
    @TableConstraint("unique_ UNIQUE (path)")
    struct FilesTbl {
        long id;

        string path;

        /// checksum is 128bit.
        long checksum0;
        long checksum1;
        Language lang;

        @ColumnName("timestamp")
        SysTime timeStamp;
    }

    immutable newFilesTbl = "new_" ~ filesTable;
    db.run(buildSchema!FilesTbl("new_"));
    auto stmt = db.prepare(format("INSERT OR IGNORE INTO %s (id,path,checksum0,checksum1,lang,timestamp)
                  SELECT id,path,checksum0,checksum1,lang,:time FROM %s",
            newFilesTbl, filesTable));
    stmt.get.bind(":time", Clock.currTime.toSqliteDateTime);
    stmt.get.execute;
    db.replaceTbl(newFilesTbl, filesTable);
}

/// 2020-12-29
void upgradeV31(ref Miniorm db) {
    db.run(buildSchema!(CoverageCodeRegionTable, CoverageInfoTable, CoverageTimeTtampTable));
}

/// 2021-01-02
void upgradeV32(ref Miniorm db) {
    immutable newFilesTbl = "new_" ~ filesTable;
    db.run(buildSchema!FilesTbl("new_"));
    db.run(format("INSERT OR IGNORE INTO %s (id,path,checksum0,checksum1,lang,timestamp,root)
                  SELECT id,path,checksum0,checksum1,lang,timestamp,0 FROM %s",
            newFilesTbl, filesTable));
    db.replaceTbl(newFilesTbl, filesTable);
}

/// 2021-01-15
void upgradeV33(ref Miniorm db) {
    db.run(buildSchema!(DependencyFileTable, DependencyRootTable));

    // add all existing files as being dependent on each other.
    // this forces, if any one of them changes, all to be re-analyzed.
    db.run(format("INSERT OR IGNORE INTO %1$s (file,checksum0,checksum1)
                  SELECT path,0,0 FROM %2$s",
            depFileTable, filesTable));
    db.run(format("INSERT OR IGNORE INTO %1$s (dep_id,file_id)
                  SELECT t0.id,t1.id FROM %2$s t0, %3$s t1", depRootTable,
            depFileTable, filesTable));
}

/// 2021-03-14
void upgradeV34(ref Miniorm db) {
    immutable newTbl = "new_" ~ mutantWorklistTable;
    db.run(buildSchema!MutantWorklistTbl("new_"));
    db.run(format("INSERT INTO %1$s (id,prio) SELECT id,0 FROM %2$s", newTbl, mutantWorklistTable));
    db.replaceTbl(newTbl, mutantWorklistTable);
}

/// 2021-03-28
void upgradeV35(ref Miniorm db) {
    @TableName(mutationStatusTable)
    @TableConstraint("checksum UNIQUE (checksum0, checksum1)")
    struct MutationStatusTbl {
        long id;
        long status;
        @ColumnName("exit_code")
        int exitCode;

        @ColumnName("compile_time_ms")
        long compileTimeMs;

        @ColumnName("test_time_ms")
        long testTimeMs;

        @ColumnName("test_cnt")
        long testCnt;

        @ColumnParam("")
        @ColumnName("update_ts")
        SysTime updated;

        @ColumnParam("")
        @ColumnName("added_ts")
        SysTime added;

        long checksum0;
        long checksum1;

        /// Priority of the mutant used when testing.
        long prio;
    }

    immutable newTbl = "new_" ~ mutationStatusTable;
    db.run(buildSchema!MutationStatusTbl("new_"));

    db.run(format("INSERT INTO %s (id,status,exit_code,compile_time_ms,test_time_ms,test_cnt,update_ts,added_ts,checksum0,checksum1,prio)
        SELECT t.id,t.status,t.exit_code,t.compile_time_ms,t.test_time_ms,t.test_cnt,t.update_ts,t.added_ts,t.checksum0,t.checksum1,0
        FROM %s t", newTbl, mutationStatusTable));
    replaceTbl(db, newTbl, mutationStatusTable);
}

/// 2021-03-29
void upgradeV36(ref Miniorm db) {
    import dextool.plugin.mutate.backend.type : Mutation;

    immutable newTbl = "new_" ~ mutationStatusTable;
    db.run(buildSchema!MutationStatusTbl("new_"));

    db.run(format(
            "INSERT INTO %s (id,status,exit_code,compile_time_ms,test_time_ms,update_ts,added_ts,checksum0,checksum1,prio)
        SELECT t.id,t.status,t.exit_code,t.compile_time_ms,t.test_time_ms,t.update_ts,t.added_ts,t.checksum0,t.checksum1,t.prio
        FROM %s t",
            newTbl, mutationStatusTable));
    replaceTbl(db, newTbl, mutationStatusTable);
}

// 2021-04-18
void upgradeV37(ref Miniorm db) {
    db.run(format("DELETE FROM %s", schemataTable));
    db.run(buildSchema!(DextoolVersionTable, SchemataTable));
}

// 2021-04-19
void upgradeV38(ref Miniorm db) {
    db.run(format("DROP TABLE %s", schemataTable));
    db.run(buildSchema!(SchemataTable));
}

// 2021-04-23
void upgradeV39(ref Miniorm db) {
    // this is just to force a re-measure of the test suite.
    db.run(format("DELETE FROM %s", runtimeHistoryTable));
}

// 2021-05-06
void upgradeV40(ref Miniorm db) {
    // force an upgrade because after this release all scheman will be zipped.
    db.run(format("DELETE FROM %s", schemataFragmentTable));
    db.run(format("DELETE FROM %s", schemataMutantTable));
    db.run(format("DELETE FROM %s", schemataTable));
    db.run(format("DELETE FROM %s", schemataUsedTable));
}

// 2021-05-09
void upgradeV41(ref Miniorm db) {
    db.run(buildSchema!(TestCmdOriginalTable));
}

// 2021-05-23
void upgradeV42(ref Miniorm db) {
    db.run(buildSchema!(TestCmdMutatedTable));
}

// 2021-06-07
void upgradeV43(ref Miniorm db) {
    immutable newTbl = "new_" ~ mutationTable;
    db.run(buildSchema!MutationTbl("new_"));

    db.run(format("INSERT INTO %s (id,mp_id,st_id,kind)
        SELECT id,mp_id,st_id,kind FROM %s WHERE st_id NOT NULL",
            newTbl, mutationTable));
    replaceTbl(db, newTbl, mutationTable);
}

// 2021-08-30
void upgradeV44(ref Miniorm db) {
    @TableName(schemaMutantQTable)
    @TablePrimaryKey("kind")
    struct SchemaMutantKindQ {
        /// mutant subtype
        long kind;

        // max 100
        long probability;
    }

    db.run(format("DROP TABLE %s", schemataUsedTable));
    db.run(buildSchema!(SchemataUsedTable, SchemaMutantKindQ));
}

// 2021-08-30
void upgradeV45(ref Miniorm db) {
    db.run(format("DROP TABLE %s", schemaMutantQTable));
    db.run(buildSchema!(SchemaMutantKindQTable));
}

// 2021-08-30
void upgradeV46(ref Miniorm db) {
    db.run(buildSchema!SchemaSizeQTable);
    // drop probability because max state where changed thus all previous values are now 10x off
    db.run("DELETE FROM " ~ schemaMutantQTable);
}

// 2021-11-01
void upgradeV47(ref Miniorm db) {
    immutable newTbl = "new_" ~ allTestCaseTable;
    db.run(buildSchema!AllTestCaseTbl("new_"));

    db.run(format("INSERT INTO %s (id,name,is_new) SELECT id,name,0 FROM %s",
            newTbl, allTestCaseTable));
    replaceTbl(db, newTbl, allTestCaseTable);
}

// 2021-11-02
void upgradeV48(ref Miniorm db) {
    db.run(buildSchema!MutantMemOverloadtWorklistTbl);
}

// 2021-11-02
void upgradeV49(ref Miniorm db) {
    immutable newTbl = "new_" ~ mutantTimeoutWorklistTable;
    db.run(buildSchema!MutantTimeoutWorklistTbl("new_"));

    db.run("INSERT INTO " ~ newTbl ~ " (id,iter) SELECT id,0 FROM " ~ mutantTimeoutWorklistTable);

    replaceTbl(db, newTbl, mutantTimeoutWorklistTable);
}

void replaceTbl(ref Miniorm db, string src, string dst) {
    db.run("DROP TABLE " ~ dst);
    db.run(format("ALTER TABLE %s RENAME TO %s", src, dst));
}

struct UpgradeTable {
    alias UpgradeFunc = void function(ref Miniorm db);
    UpgradeFunc[long] tbl;
    alias tbl this;

    immutable long latestSchemaVersion;
}

/** Inspects a module for functions starting with upgradeV to create a table of
 * functions that can be used to upgrade a database.
 */
UpgradeTable makeUpgradeTable() {
    import std.algorithm : sort, startsWith;
    import std.conv : to;
    import std.typecons : Tuple;

    immutable prefix = "upgradeV";

    alias Module = dextool.plugin.mutate.backend.database.schema;

    // the second parameter is the database version to upgrade FROM.
    alias UpgradeFx = Tuple!(UpgradeTable.UpgradeFunc, long);

    UpgradeFx[] upgradeFx;
    long last_from;

    static foreach (member; __traits(allMembers, Module)) {
        static if (member.startsWith(prefix))
            upgradeFx ~= UpgradeFx(&__traits(getMember, Module, member),
                    member[prefix.length .. $].to!long);
    }

    typeof(UpgradeTable.tbl) tbl;
    foreach (fn; upgradeFx.sort!((a, b) => a[1] < b[1])) {
        last_from = fn[1];
        tbl[last_from] = fn[0];
    }

    return UpgradeTable(tbl, last_from + 1);
}