yahoo/pngjs-image

// Copyright 2015 Yahoo! Inc.
// Copyrights licensed under the Mit License. See the accompanying LICENSE file for terms.

/**
 * @class tIME
 * @module PNG
 * @submodule PNGChunks
 */
module.exports = {

    /**
     * Gets the sequence
     *
     * @method getSequence
     * @return {int}
     */
    getSequence: function () {
        return 100;
    },


    /**
     * Gets the date
     *
     * @method getDate
     * @return {Date}
     */
    getDate: function () {
        return this._date || new Date();
    },

    /**
     * Sets the date
     *
     * @method setDate
     * @param {Date} date
     */
    setDate: function (date) {
        this._date = date;
    },


    /**
     * Parsing of chunk data
     *
     * Phase 1
     *
     * @method parse
     * @param {BufferedStream} stream Data stream
     * @param {int} length Length of chunk data
     * @param {boolean} strict Should parsing be strict?
     * @param {object} options Decoding options
     */
    parse: function (stream, length, strict, options) {

        var year, month, day, hour, minute, second;

        // Validation
        if (strict && (this.getFirstChunk(this.getType(), false) !== null)) {
            throw new Error('Only one ' + this.getType() + ' is allowed in the data.');
        }

        if ((strict && (length !== 7)) || (length < 7)) {
            throw new Error('The length of the ' + this.getType() + ' chunk should be 7 but is ' + length +'.');
        }

        year = stream.readUInt16BE();
        month = stream.readUInt8();
        day = stream.readUInt8();
        hour = stream.readUInt8();
        minute = stream.readUInt8();
        second = stream.readUInt8();

        this.setDate(new Date(Date.UTC(year, month - 1, day, hour, minute, second === 60 ? 59 : second)));
    },

    /**
     * Gathers chunk-data from decoded chunks
     *
     * Phase 5
     *
     * @static
     * @method decodeData
     * @param {object} data Data-object that will be used to export values
     * @param {boolean} strict Should parsing be strict?
     * @param {object} options Decoding options
     */
    decodeData: function (data, strict, options) {

        var chunks = this.getChunksByType(this.getType());

        if (!chunks) {
            return ;
        }

        if (strict && (chunks.length !== 1)) {
            throw new Error('Not more than one chunk allowed for ' + this.getType() + '.');
        }

        data.volatile = data.volatile || {};
        data.volatile.modificationDate = chunks[0].getDate();
    },


    /**
     * Returns a list of chunks to be added to the data-stream
     *
     * Phase 1
     *
     * @static
     * @method encodeData
     * @param {Buffer} image Image data
     * @param {object} options Encoding options
     * @return {Chunk[]} List of chunks to encode
     */
    encodeData: function (image, options) {

        if (options.modificationDate) {

            var chunk = this.createChunk(this.getType(), this.getChunks());

            chunk.setDate(options.modificationDate);

            return [chunk];
        } else {
            return [];
        }
    },

    /**
     * Composing of chunk data
     *
     * Phase 4
     *
     * @method compose
     * @param {BufferedStream} stream Data stream
     * @param {object} options Encoding options
     */
    compose: function (stream, options) {

        var date = this.getDate();

        stream.writeUInt16BE(date.getUTCFullYear());
        stream.writeUInt8(date.getUTCMonth() + 1);
        stream.writeUInt8(date.getUTCDate());
        stream.writeUInt8(date.getUTCHours());
        stream.writeUInt8(date.getUTCMinutes());
        stream.writeUInt8(date.getUTCSeconds());
    }
};