/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */

#include "BufferedTokenStream.h"

#include "Exceptions.h"
#include "Lexer.h"
#include "RuleContext.h"
#include "WritableToken.h"
#include "misc/Interval.h"
#include "support/CPPUtils.h"

using namespace antlr4;
using namespace antlrcpp;

BufferedTokenStream::BufferedTokenStream(TokenSource* tokenSource) : _tokenSource(tokenSource) {
    InitializeInstanceFields();
}

TokenSource* BufferedTokenStream::getTokenSource() const {
    return _tokenSource;
}

size_t BufferedTokenStream::index() {
    return _p;
}

ssize_t BufferedTokenStream::mark() {
    return 0;
}

void BufferedTokenStream::release(ssize_t /*marker*/) {
    // no resources to release
}

void BufferedTokenStream::reset() {
    seek(0);
}

void BufferedTokenStream::seek(size_t index) {
    lazyInit();
    _p = adjustSeekIndex(index);
}

size_t BufferedTokenStream::size() {
    return _tokens.size();
}

void BufferedTokenStream::consume() {
    bool skipEofCheck = false;
    if (!_needSetup) {
        if (_fetchedEOF) {
            // the last token in tokens is EOF. skip check if p indexes any
            // fetched token except the last.
            skipEofCheck = _p < _tokens.size() - 1;
        } else {
            // no EOF token in tokens. skip check if p indexes a fetched token.
            skipEofCheck = _p < _tokens.size();
        }
    } else {
        // not yet initialized
        skipEofCheck = false;
    }

    if (!skipEofCheck && LA(1) == Token::EOF) {
        throw IllegalStateException("cannot consume EOF");
    }

    if (sync(_p + 1)) {
        _p = adjustSeekIndex(_p + 1);
    }
}

bool BufferedTokenStream::sync(size_t i) {
    if (i + 1 < _tokens.size())
        return true;
    size_t n = i - _tokens.size() + 1; // how many more elements we need?

    if (n > 0) {
        size_t fetched = fetch(n);
        return fetched >= n;
    }

    return true;
}

size_t BufferedTokenStream::fetch(size_t n) {
    if (_fetchedEOF) {
        return 0;
    }

    size_t i = 0;
    while (i < n) {
        std::unique_ptr<Token> t(_tokenSource->nextToken());

        if (is<WritableToken*>(t.get())) {
            (static_cast<WritableToken*>(t.get()))->setTokenIndex(_tokens.size());
        }

        _tokens.push_back(std::move(t));
        ++i;

        if (_tokens.back()->getType() == Token::EOF) {
            _fetchedEOF = true;
            break;
        }
    }

    return i;
}

Token* BufferedTokenStream::get(size_t i) const {
    if (i >= _tokens.size()) {
        throw IndexOutOfBoundsException(std::string("token index ") + std::to_string(i) +
                                        std::string(" out of range 0..") +
                                        std::to_string(_tokens.size() - 1));
    }
    return _tokens[i].get();
}

std::vector<Token*> BufferedTokenStream::get(size_t start, size_t stop) {
    std::vector<Token*> subset;

    lazyInit();

    if (_tokens.empty()) {
        return subset;
    }

    if (stop >= _tokens.size()) {
        stop = _tokens.size() - 1;
    }
    for (size_t i = start; i <= stop; i++) {
        Token* t = _tokens[i].get();
        if (t->getType() == Token::EOF) {
            break;
        }
        subset.push_back(t);
    }
    return subset;
}

size_t BufferedTokenStream::LA(ssize_t i) {
    return LT(i)->getType();
}

Token* BufferedTokenStream::LB(size_t k) {
    if (k > _p) {
        return nullptr;
    }
    return _tokens[_p - k].get();
}

Token* BufferedTokenStream::LT(ssize_t k) {
    lazyInit();
    if (k == 0) {
        return nullptr;
    }
    if (k < 0) {
        return LB(-k);
    }

    size_t i = _p + k - 1;
    sync(i);
    if (i >= _tokens.size()) { // return EOF token
                               // EOF must be last token
        return _tokens.back().get();
    }

    return _tokens[i].get();
}

ssize_t BufferedTokenStream::adjustSeekIndex(size_t i) {
    return i;
}

void BufferedTokenStream::lazyInit() {
    if (_needSetup) {
        setup();
    }
}

void BufferedTokenStream::setup() {
    _needSetup = false;
    sync(0);
    _p = adjustSeekIndex(0);
}

void BufferedTokenStream::setTokenSource(TokenSource* tokenSource) {
    _tokenSource = tokenSource;
    _tokens.clear();
    _fetchedEOF = false;
    _needSetup = true;
}

std::vector<Token*> BufferedTokenStream::getTokens() {
    std::vector<Token*> result;
    for (auto& t : _tokens)
        result.push_back(t.get());
    return result;
}

std::vector<Token*> BufferedTokenStream::getTokens(size_t start, size_t stop) {
    return getTokens(start, stop, std::vector<size_t>());
}

std::vector<Token*> BufferedTokenStream::getTokens(
    size_t start, size_t stop, const std::vector<size_t>& types) {
    lazyInit();
    if (stop >= _tokens.size() || start >= _tokens.size()) {
        throw IndexOutOfBoundsException(
            std::string("start ") + std::to_string(start) + std::string(" or stop ") +
            std::to_string(stop) + std::string(" not in 0..") + std::to_string(_tokens.size() - 1));
    }

    std::vector<Token*> filteredTokens;

    if (start > stop) {
        return filteredTokens;
    }

    for (size_t i = start; i <= stop; i++) {
        Token* tok = _tokens[i].get();

        if (types.empty() || std::find(types.begin(), types.end(), tok->getType()) != types.end()) {
            filteredTokens.push_back(tok);
        }
    }
    return filteredTokens;
}

std::vector<Token*> BufferedTokenStream::getTokens(size_t start, size_t stop, size_t ttype) {
    std::vector<size_t> s;
    s.push_back(ttype);
    return getTokens(start, stop, s);
}

ssize_t BufferedTokenStream::nextTokenOnChannel(size_t i, size_t channel) {
    sync(i);
    if (i >= size()) {
        return size() - 1;
    }

    Token* token = _tokens[i].get();
    while (token->getChannel() != channel) {
        if (token->getType() == Token::EOF) {
            return i;
        }
        i++;
        sync(i);
        token = _tokens[i].get();
    }
    return i;
}

ssize_t BufferedTokenStream::previousTokenOnChannel(size_t i, size_t channel) {
    sync(i);
    if (i >= size()) {
        // the EOF token is on every channel
        return size() - 1;
    }

    while (true) {
        Token* token = _tokens[i].get();
        if (token->getType() == Token::EOF || token->getChannel() == channel) {
            return i;
        }

        if (i == 0)
            return -1;
        i--;
    }
    return i;
}

std::vector<Token*> BufferedTokenStream::getHiddenTokensToRight(
    size_t tokenIndex, ssize_t channel) {
    lazyInit();
    if (tokenIndex >= _tokens.size()) {
        throw IndexOutOfBoundsException(
            std::to_string(tokenIndex) + " not in 0.." + std::to_string(_tokens.size() - 1));
    }

    ssize_t nextOnChannel = nextTokenOnChannel(tokenIndex + 1, Lexer::DEFAULT_TOKEN_CHANNEL);
    size_t to;
    size_t from = tokenIndex + 1;
    // if none onchannel to right, nextOnChannel=-1 so set to = last token
    if (nextOnChannel == -1) {
        to = static_cast<ssize_t>(size() - 1);
    } else {
        to = nextOnChannel;
    }

    return filterForChannel(from, to, channel);
}

std::vector<Token*> BufferedTokenStream::getHiddenTokensToRight(size_t tokenIndex) {
    return getHiddenTokensToRight(tokenIndex, -1);
}

std::vector<Token*> BufferedTokenStream::getHiddenTokensToLeft(size_t tokenIndex, ssize_t channel) {
    lazyInit();
    if (tokenIndex >= _tokens.size()) {
        throw IndexOutOfBoundsException(
            std::to_string(tokenIndex) + " not in 0.." + std::to_string(_tokens.size() - 1));
    }

    if (tokenIndex == 0) {
        // Obviously no tokens can appear before the first token.
        return {};
    }

    ssize_t prevOnChannel = previousTokenOnChannel(tokenIndex - 1, Lexer::DEFAULT_TOKEN_CHANNEL);
    if (prevOnChannel == static_cast<ssize_t>(tokenIndex - 1)) {
        return {};
    }
    // if none onchannel to left, prevOnChannel=-1 then from=0
    size_t from = static_cast<size_t>(prevOnChannel + 1);
    size_t to = tokenIndex - 1;

    return filterForChannel(from, to, channel);
}

std::vector<Token*> BufferedTokenStream::getHiddenTokensToLeft(size_t tokenIndex) {
    return getHiddenTokensToLeft(tokenIndex, -1);
}

std::vector<Token*> BufferedTokenStream::filterForChannel(size_t from, size_t to, ssize_t channel) {
    std::vector<Token*> hidden;
    for (size_t i = from; i <= to; i++) {
        Token* t = _tokens[i].get();
        if (channel == -1) {
            if (t->getChannel() != Lexer::DEFAULT_TOKEN_CHANNEL) {
                hidden.push_back(t);
            }
        } else {
            if (t->getChannel() == static_cast<size_t>(channel)) {
                hidden.push_back(t);
            }
        }
    }

    return hidden;
}

bool BufferedTokenStream::isInitialized() const {
    return !_needSetup;
}

/**
 * Get the text of all tokens in this buffer.
 */
std::string BufferedTokenStream::getSourceName() const {
    return _tokenSource->getSourceName();
}

std::string BufferedTokenStream::getText() {
    fill();
    return getText(misc::Interval(0U, size() - 1));
}

std::string BufferedTokenStream::getText(const misc::Interval& interval) {
    lazyInit();
    size_t start = interval.a;
    size_t stop = interval.b;
    if (start == INVALID_INDEX || stop == INVALID_INDEX) {
        return "";
    }
    sync(stop);
    if (stop >= _tokens.size()) {
        stop = _tokens.size() - 1;
    }

    std::stringstream ss;
    for (size_t i = start; i <= stop; i++) {
        Token* t = _tokens[i].get();
        if (t->getType() == Token::EOF) {
            break;
        }
        ss << t->getText();
    }
    return ss.str();
}

std::string BufferedTokenStream::getText(RuleContext* ctx) {
    return getText(ctx->getSourceInterval());
}

std::string BufferedTokenStream::getText(Token* start, Token* stop) {
    if (start != nullptr && stop != nullptr) {
        return getText(misc::Interval(start->getTokenIndex(), stop->getTokenIndex()));
    }

    return "";
}

void BufferedTokenStream::fill() {
    lazyInit();
    const size_t blockSize = 1000;
    while (true) {
        size_t fetched = fetch(blockSize);
        if (fetched < blockSize) {
            return;
        }
    }
}

void BufferedTokenStream::InitializeInstanceFields() {
    _needSetup = true;
    _fetchedEOF = false;
}
