'use strict';

var WritableStream = require('stream').Writable,
    inherits = require('util').inherits,
    Parser = require('./index');

var ParserStream = module.exports = function (options) {
    WritableStream.call(this);

    this.parser = new Parser(options);

    this.lastChunkWritten = false;
    this.writeCallback = null;
    this.pausedByScript = false;

    this.document = this.parser.treeAdapter.createDocument();

    this.pendingHtmlInsertions = [];

    this._resume = this._resume.bind(this);
    this._documentWrite = this._documentWrite.bind(this);
    this._scriptHandler = this._scriptHandler.bind(this);

    this.parser._bootstrap(this.document, null);
};

inherits(ParserStream, WritableStream);

//WritableStream implementation
ParserStream.prototype._write = function (chunk, encoding, callback) {
    this.writeCallback = callback;
    this.parser.tokenizer.write(chunk.toString('utf8'), this.lastChunkWritten);
    this._runParsingLoop();
};

ParserStream.prototype.end = function (chunk, encoding, callback) {
    this.lastChunkWritten = true;
    WritableStream.prototype.end.call(this, chunk || '', encoding, callback);
};

//Scriptable parser implementation
ParserStream.prototype._runParsingLoop = function () {
    this.parser.runParsingLoopForCurrentChunk(this.writeCallback, this._scriptHandler);
};

ParserStream.prototype._resume = function () {
    if (!this.pausedByScript)
        throw new Error('Parser was already resumed');

    while (this.pendingHtmlInsertions.length) {
        var html = this.pendingHtmlInsertions.pop();

        this.parser.tokenizer.insertHtmlAtCurrentPos(html);
    }

    this.pausedByScript = false;

    //NOTE: keep parsing if we don't wait for the next input chunk
    if (this.parser.tokenizer.active)
        this._runParsingLoop();
};

ParserStream.prototype._documentWrite = function (html) {
    if (!this.parser.stopped)
        this.pendingHtmlInsertions.push(html);
};

ParserStream.prototype._scriptHandler = function (scriptElement) {
    if (this.listeners('script').length) {
        this.pausedByScript = true;
        this.emit('script', scriptElement, this._documentWrite, this._resume);
    }
    else
        this._runParsingLoop();
};