// Written in the D programming language.
/**
 * Copyright: Copyright (c) 2015-2018, Joakim Brännström. All rights reserved.
 * Author: Joakim Brännström (joakim.brannstrom@gmx.com)
 *
 * Copyright: Copyright (c) 2016 Wojciech Szęszoł. All rights reserved.
 * Authors: Wojciech Szęszoł
 * Version: Initial created: Feb 14, 2016
 * License: $(LINK2 http://www.boost.org/LICENSE_1_0.txt, Boost Software License 1.0)
 *
 * Only kept utility functionality and comments of the original implementation.
 * The rest is synchronized with Token.d in DStep.
 */
module clang.Token;

import std.conv : to;
import std.typecons;

import clang.c.Index;

import clang.Cursor;
import clang.SourceLocation;
import clang.SourceRange;
import clang.TranslationUnit;
import clang.Util;
import clang.Visitor;

@property auto toString(Token tok) {
    import std.format : format;

    return format("%s [%s %s]", tok.spelling, tok.kind, to!string(tok.cursor.cx),);
}

@property auto toString(ref TokenRange toks) {
    import std..string;

    string s;

    foreach (t; toks) {
        s ~= t.spelling ~ " ";
    }

    return s.strip;
}

/** Represents a single token from the preprocessor.
 *
 * Tokens are effectively segments of source code. Source code is first parsed
 * into tokens before being converted into the AST and Cursors.
 *
 * Tokens are obtained from parsed TranslationUnit instances. You currently
 * can't create tokens manually.
 *
 * To keep the tokens efficient they are pointers into the range of tokens
 * derived from clang. This mean that the lifetime of a token is coupled to the
 * range.
 */
struct Token {
    private {
        CXTranslationUnit translationUnit;
        CXToken* ctok;
    }

    this(ref const CXTranslationUnit tu, ref const CXToken t) {
        this.translationUnit = cast(CXTranslationUnit)(tu);
        this.ctok = cast(CXToken*)(&t);
    }

    /// Obtain the TokenKind of the current token.
    @property CXTokenKind kind() const {
        return clang_getTokenKind(cast(CXToken)(*ctok));
    }

    /** The spelling of this token.
     *
     * This is the textual representation of the token in source.
     */
    @property string spelling() const {
        auto r = clang_getTokenSpelling(cast(CXTranslationUnit)(translationUnit),
                cast(CXToken)(*ctok));
        return toD(r);
    }

    /// The SourceLocation this Token occurs at.
    @property SourceLocation location() const {
        auto r = clang_getTokenLocation(cast(CXTranslationUnit)(translationUnit),
                cast(CXToken)(*ctok));
        return SourceLocation(r);
    }

    /// The SourceRange this Token occupies.
    @property SourceRange extent() const {
        auto r = clang_getTokenExtent(cast(CXTranslationUnit)(translationUnit),
                cast(CXToken)(*ctok));
        return SourceRange(r);
    }

    // TODO: maybe this should be remove. If so then it would be possible to
    // remove translationUnit and thus make this struct lighter.
    /// The Cursor this Token corresponds to.
    @property Cursor cursor() {
        auto c = Cursor.empty;
        clang_annotateTokens(translationUnit, ctok, 1, &c.cx);
        return c;
    }
}

struct TokenRange {
    private static struct Container {
        CXTranslationUnit translationUnit;
        CXToken* tokens;
        uint numTokens;

        ~this() {
            if (tokens != null) {
                clang_disposeTokens(translationUnit, tokens, numTokens);
            }
        }
    }

    private RefCounted!(Container) container;
    private size_t begin;
    private size_t end;

    private static RefCounted!(Container) makeContainer(
            CXTranslationUnit translationUnit, CXToken* tokens, uint numTokens) {
        RefCounted!(Container) result;
        result.translationUnit = translationUnit;
        result.tokens = tokens;
        result.numTokens = numTokens;
        return result;
    }

    private this(RefCounted!(Container) container, size_t begin, size_t end) {
        this.container = container;
        this.begin = begin;
        this.end = end;
    }

    this(CXTranslationUnit translationUnit, CXToken* tokens, uint numTokens) {
        container = makeContainer(translationUnit, tokens, numTokens);
        begin = 0;
        end = numTokens;
    }

    @property bool empty() const {
        return begin >= end;
    }

    @property Token front() const {
        return Token(container.translationUnit, container.tokens[begin]);
    }

    @property Token back() const {
        return Token(container.translationUnit, container.tokens[end - 1]);
    }

    @property void popFront() {
        ++begin;
    }

    @property void popBack() {
        --end;
    }

    @property TokenRange save() {
        return this;
    }

    @property size_t length() const {
        assert(begin <= end);
        return end - begin;
    }

    Token opIndex(size_t index) const {
        assert(begin + index < end);
        return Token(container.translationUnit, container.tokens[begin + index]);
    }

    TokenRange opSlice(size_t begin, size_t end) {
        assert(this.begin + begin <= this.end);
        assert(this.begin + end <= this.end);
        return TokenRange(container, this.begin + begin, this.begin + end);
    }

    size_t opDollar() const {
        return length;
    }
}