/* 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 "TokenStreamRewriter.h"

#include "Exceptions.h"
#include "Token.h"
#include "TokenStream.h"
#include "misc/Interval.h"

using namespace antlr4;

using antlr4::misc::Interval;

TokenStreamRewriter::RewriteOperation::RewriteOperation(
    TokenStreamRewriter* outerInstance_, size_t index_)
    : outerInstance(outerInstance_) {

    InitializeInstanceFields();
    this->index = index_;
}

TokenStreamRewriter::RewriteOperation::RewriteOperation(
    TokenStreamRewriter* outerInstance_, size_t index_, const std::string& text_)
    : outerInstance(outerInstance_) {

    InitializeInstanceFields();
    this->index = index_;
    this->text = text_;
}

TokenStreamRewriter::RewriteOperation::~RewriteOperation() {}

size_t TokenStreamRewriter::RewriteOperation::execute(std::string* /*buf*/) {
    return index;
}

std::string TokenStreamRewriter::RewriteOperation::toString() {
    std::string opName = "TokenStreamRewriter";
    size_t dollarIndex = opName.find('$');
    opName = opName.substr(dollarIndex + 1, opName.length() - (dollarIndex + 1));
    return "<" + opName + "@" + outerInstance->tokens->get(dollarIndex)->getText() + ":\"" + text +
           "\">";
}

void TokenStreamRewriter::RewriteOperation::InitializeInstanceFields() {
    instructionIndex = 0;
    index = 0;
}

TokenStreamRewriter::InsertBeforeOp::InsertBeforeOp(
    TokenStreamRewriter* outerInstance_, size_t index_, const std::string& text_)
    : RewriteOperation(outerInstance_, index_, text_), outerInstance(outerInstance_) {}

size_t TokenStreamRewriter::InsertBeforeOp::execute(std::string* buf) {
    buf->append(text);
    if (outerInstance->tokens->get(index)->getType() != Token::EOF) {
        buf->append(outerInstance->tokens->get(index)->getText());
    }
    return index + 1;
}

TokenStreamRewriter::ReplaceOp::ReplaceOp(
    TokenStreamRewriter* outerInstance_, size_t from, size_t to, const std::string& text)
    : RewriteOperation(outerInstance_, from, text), outerInstance(outerInstance_) {

    InitializeInstanceFields();
    lastIndex = to;
}

size_t TokenStreamRewriter::ReplaceOp::execute(std::string* buf) {
    buf->append(text);
    return lastIndex + 1;
}

std::string TokenStreamRewriter::ReplaceOp::toString() {
    if (text.empty()) {
        return "<DeleteOp@" + outerInstance->tokens->get(index)->getText() + ".." +
               outerInstance->tokens->get(lastIndex)->getText() + ">";
    }
    return "<ReplaceOp@" + outerInstance->tokens->get(index)->getText() + ".." +
           outerInstance->tokens->get(lastIndex)->getText() + ":\"" + text + "\">";
}

void TokenStreamRewriter::ReplaceOp::InitializeInstanceFields() {
    lastIndex = 0;
}

//------------------ TokenStreamRewriter
//-------------------------------------------------------------------------------

const std::string TokenStreamRewriter::DEFAULT_PROGRAM_NAME = "default";

TokenStreamRewriter::TokenStreamRewriter(TokenStream* tokens_) : tokens(tokens_) {
    _programs[DEFAULT_PROGRAM_NAME].reserve(PROGRAM_INIT_SIZE);
}

TokenStreamRewriter::~TokenStreamRewriter() {
    for (auto program : _programs) {
        for (auto* operation : program.second) {
            delete operation;
        }
    }
}

TokenStream* TokenStreamRewriter::getTokenStream() {
    return tokens;
}

void TokenStreamRewriter::rollback(size_t instructionIndex) {
    rollback(DEFAULT_PROGRAM_NAME, instructionIndex);
}

void TokenStreamRewriter::rollback(const std::string& programName, size_t instructionIndex) {
    std::vector<RewriteOperation*> is = _programs[programName];
    if (is.size() > 0) {
        _programs.insert({programName, std::vector<RewriteOperation*>(is.begin() + MIN_TOKEN_INDEX,
                                           is.begin() + instructionIndex)});
    }
}

void TokenStreamRewriter::deleteProgram() {
    deleteProgram(DEFAULT_PROGRAM_NAME);
}

void TokenStreamRewriter::deleteProgram(const std::string& programName) {
    rollback(programName, MIN_TOKEN_INDEX);
}

void TokenStreamRewriter::insertAfter(Token* t, const std::string& text) {
    insertAfter(DEFAULT_PROGRAM_NAME, t, text);
}

void TokenStreamRewriter::insertAfter(size_t index, const std::string& text) {
    insertAfter(DEFAULT_PROGRAM_NAME, index, text);
}

void TokenStreamRewriter::insertAfter(
    const std::string& programName, Token* t, const std::string& text) {
    insertAfter(programName, t->getTokenIndex(), text);
}

void TokenStreamRewriter::insertAfter(
    const std::string& programName, size_t index, const std::string& text) {
    // to insert after, just insert before next index (even if past end)
    insertBefore(programName, index + 1, text);
}

void TokenStreamRewriter::insertBefore(Token* t, const std::string& text) {
    insertBefore(DEFAULT_PROGRAM_NAME, t, text);
}

void TokenStreamRewriter::insertBefore(size_t index, const std::string& text) {
    insertBefore(DEFAULT_PROGRAM_NAME, index, text);
}

void TokenStreamRewriter::insertBefore(
    const std::string& programName, Token* t, const std::string& text) {
    insertBefore(programName, t->getTokenIndex(), text);
}

void TokenStreamRewriter::insertBefore(
    const std::string& programName, size_t index, const std::string& text) {
    RewriteOperation* op = new InsertBeforeOp(this, index, text); /* mem-check: deleted in d-tor */
    std::vector<RewriteOperation*>& rewrites = getProgram(programName);
    op->instructionIndex = rewrites.size();
    rewrites.push_back(op);
}

void TokenStreamRewriter::replace(size_t index, const std::string& text) {
    replace(DEFAULT_PROGRAM_NAME, index, index, text);
}

void TokenStreamRewriter::replace(size_t from, size_t to, const std::string& text) {
    replace(DEFAULT_PROGRAM_NAME, from, to, text);
}

void TokenStreamRewriter::replace(Token* indexT, const std::string& text) {
    replace(DEFAULT_PROGRAM_NAME, indexT, indexT, text);
}

void TokenStreamRewriter::replace(Token* from, Token* to, const std::string& text) {
    replace(DEFAULT_PROGRAM_NAME, from, to, text);
}

void TokenStreamRewriter::replace(
    const std::string& programName, size_t from, size_t to, const std::string& text) {
    if (from > to || to >= tokens->size()) {
        throw IllegalArgumentException("replace: range invalid: " + std::to_string(from) + ".." +
                                       std::to_string(to) +
                                       "(size = " + std::to_string(tokens->size()) + ")");
    }
    RewriteOperation* op = new ReplaceOp(this, from, to, text); /* mem-check: deleted in d-tor */
    std::vector<RewriteOperation*>& rewrites = getProgram(programName);
    op->instructionIndex = rewrites.size();
    rewrites.push_back(op);
}

void TokenStreamRewriter::replace(
    const std::string& programName, Token* from, Token* to, const std::string& text) {
    replace(programName, from->getTokenIndex(), to->getTokenIndex(), text);
}

void TokenStreamRewriter::Delete(size_t index) {
    Delete(DEFAULT_PROGRAM_NAME, index, index);
}

void TokenStreamRewriter::Delete(size_t from, size_t to) {
    Delete(DEFAULT_PROGRAM_NAME, from, to);
}

void TokenStreamRewriter::Delete(Token* indexT) {
    Delete(DEFAULT_PROGRAM_NAME, indexT, indexT);
}

void TokenStreamRewriter::Delete(Token* from, Token* to) {
    Delete(DEFAULT_PROGRAM_NAME, from, to);
}

void TokenStreamRewriter::Delete(const std::string& programName, size_t from, size_t to) {
    std::string nullString;
    replace(programName, from, to, nullString);
}

void TokenStreamRewriter::Delete(const std::string& programName, Token* from, Token* to) {
    std::string nullString;
    replace(programName, from, to, nullString);
}

size_t TokenStreamRewriter::getLastRewriteTokenIndex() {
    return getLastRewriteTokenIndex(DEFAULT_PROGRAM_NAME);
}

size_t TokenStreamRewriter::getLastRewriteTokenIndex(const std::string& programName) {
    if (_lastRewriteTokenIndexes.find(programName) == _lastRewriteTokenIndexes.end()) {
        return INVALID_INDEX;
    }
    return _lastRewriteTokenIndexes[programName];
}

void TokenStreamRewriter::setLastRewriteTokenIndex(const std::string& programName, size_t i) {
    _lastRewriteTokenIndexes.insert({programName, i});
}

std::vector<TokenStreamRewriter::RewriteOperation*>& TokenStreamRewriter::getProgram(
    const std::string& name) {
    auto iterator = _programs.find(name);
    if (iterator == _programs.end()) {
        return initializeProgram(name);
    }
    return iterator->second;
}

std::vector<TokenStreamRewriter::RewriteOperation*>& TokenStreamRewriter::initializeProgram(
    const std::string& name) {
    _programs[name].reserve(PROGRAM_INIT_SIZE);
    return _programs[name];
}

std::string TokenStreamRewriter::getText() {
    return getText(DEFAULT_PROGRAM_NAME, Interval(0UL, tokens->size() - 1));
}

std::string TokenStreamRewriter::getText(std::string programName) {
    return getText(programName, Interval(0UL, tokens->size() - 1));
}

std::string TokenStreamRewriter::getText(const Interval& interval) {
    return getText(DEFAULT_PROGRAM_NAME, interval);
}

std::string TokenStreamRewriter::getText(const std::string& programName, const Interval& interval) {
    std::vector<TokenStreamRewriter::RewriteOperation*>& rewrites = _programs[programName];
    size_t start = interval.a;
    size_t stop = interval.b;

    // ensure start/end are in range
    if (stop > tokens->size() - 1) {
        stop = tokens->size() - 1;
    }
    if (start == INVALID_INDEX) {
        start = 0;
    }

    if (rewrites.empty() || rewrites.empty()) {
        return tokens->getText(interval); // no instructions to execute
    }
    std::string buf;

    // First, optimize instruction stream
    std::unordered_map<size_t, TokenStreamRewriter::RewriteOperation*> indexToOp =
        reduceToSingleOperationPerIndex(rewrites);

    // Walk buffer, executing instructions and emitting tokens
    size_t i = start;
    while (i <= stop && i < tokens->size()) {
        RewriteOperation* op = indexToOp[i];
        indexToOp.erase(i); // remove so any left have index size-1
        Token* t = tokens->get(i);
        if (op == nullptr) {
            // no operation at that index, just dump token
            if (t->getType() != Token::EOF) {
                buf.append(t->getText());
            }
            i++; // move to next token
        } else {
            i = op->execute(&buf); // execute operation and skip
        }
    }

    // include stuff after end if it's last index in buffer
    // So, if they did an insertAfter(lastValidIndex, "foo"), include
    // foo if end==lastValidIndex.
    if (stop == tokens->size() - 1) {
        // Scan any remaining operations after last token
        // should be included (they will be inserts).
        for (auto op : indexToOp) {
            if (op.second->index >= tokens->size() - 1) {
                buf.append(op.second->text);
            }
        }
    }
    return buf;
}

std::unordered_map<size_t, TokenStreamRewriter::RewriteOperation*>
TokenStreamRewriter::reduceToSingleOperationPerIndex(
    std::vector<TokenStreamRewriter::RewriteOperation*>& rewrites) {

    // WALK REPLACES
    for (size_t i = 0; i < rewrites.size(); ++i) {
        TokenStreamRewriter::RewriteOperation* op = rewrites[i];
        ReplaceOp* rop = dynamic_cast<ReplaceOp*>(op);
        if (rop == nullptr)
            continue;

        // Wipe prior inserts within range
        std::vector<InsertBeforeOp*> inserts = getKindOfOps<InsertBeforeOp>(rewrites, i);
        for (auto* iop : inserts) {
            if (iop->index == rop->index) {
                // E.g., insert before 2, delete 2..2; update replace
                // text to include insert before, kill insert
                delete rewrites[iop->instructionIndex];
                rewrites[iop->instructionIndex] = nullptr;
                rop->text = iop->text + (!rop->text.empty() ? rop->text : "");
            } else if (iop->index > rop->index && iop->index <= rop->lastIndex) {
                // delete insert as it's a no-op.
                delete rewrites[iop->instructionIndex];
                rewrites[iop->instructionIndex] = nullptr;
            }
        }
        // Drop any prior replaces contained within
        std::vector<ReplaceOp*> prevReplaces = getKindOfOps<ReplaceOp>(rewrites, i);
        for (auto* prevRop : prevReplaces) {
            if (prevRop->index >= rop->index && prevRop->lastIndex <= rop->lastIndex) {
                // delete replace as it's a no-op.
                delete rewrites[prevRop->instructionIndex];
                rewrites[prevRop->instructionIndex] = nullptr;
                continue;
            }
            // throw exception unless disjoint or identical
            bool disjoint = prevRop->lastIndex < rop->index || prevRop->index > rop->lastIndex;
            // Delete special case of replace (text==null):
            // D.i-j.u D.x-y.v    | boundaries overlap    combine to max(min)..max(right)
            if (prevRop->text.empty() && rop->text.empty() && !disjoint) {
                delete rewrites[prevRop->instructionIndex];
                rewrites[prevRop->instructionIndex] = nullptr; // kill first delete
                rop->index = std::min(prevRop->index, rop->index);
                rop->lastIndex = std::max(prevRop->lastIndex, rop->lastIndex);
                std::cout << "new rop " << rop << std::endl;
            } else if (!disjoint) {
                throw IllegalArgumentException("replace op boundaries of " + rop->toString() +
                                               " overlap with previous " + prevRop->toString());
            }
        }
    }

    // WALK INSERTS
    for (size_t i = 0; i < rewrites.size(); i++) {
        InsertBeforeOp* iop = dynamic_cast<InsertBeforeOp*>(rewrites[i]);
        if (iop == nullptr)
            continue;

        // combine current insert with prior if any at same index

        std::vector<InsertBeforeOp*> prevInserts = getKindOfOps<InsertBeforeOp>(rewrites, i);
        for (auto* prevIop : prevInserts) {
            if (prevIop->index ==
                iop->index) { // combine objects
                              // convert to strings...we're in process of toString'ing
                              // whole token buffer so no lazy eval issue with any templates
                iop->text = catOpText(&iop->text, &prevIop->text);
                // delete redundant prior insert
                delete rewrites[prevIop->instructionIndex];
                rewrites[prevIop->instructionIndex] = nullptr;
            }
        }
        // look for replaces where iop.index is in range; error
        std::vector<ReplaceOp*> prevReplaces = getKindOfOps<ReplaceOp>(rewrites, i);
        for (auto* rop : prevReplaces) {
            if (iop->index == rop->index) {
                rop->text = catOpText(&iop->text, &rop->text);
                delete rewrites[i];
                rewrites[i] = nullptr; // delete current insert
                continue;
            }
            if (iop->index >= rop->index && iop->index <= rop->lastIndex) {
                throw IllegalArgumentException("insert op " + iop->toString() +
                                               " within boundaries of previous " + rop->toString());
            }
        }
    }

    std::unordered_map<size_t, TokenStreamRewriter::RewriteOperation*> m;
    for (TokenStreamRewriter::RewriteOperation* op : rewrites) {
        if (op == nullptr) { // ignore deleted ops
            continue;
        }
        if (m.count(op->index) > 0) {
            throw RuntimeException("should only be one op per index");
        }
        m[op->index] = op;
    }

    return m;
}

std::string TokenStreamRewriter::catOpText(std::string* a, std::string* b) {
    std::string x = "";
    std::string y = "";
    if (a != nullptr) {
        x = *a;
    }
    if (b != nullptr) {
        y = *b;
    }
    return x + y;
}
