/*jshint node:true*/
'use strict';

var fs = require('fs');
var path = require('path');
var async = require('async');
var utils = require('./utils');

/*
 *! Capability helpers
 */

var avCodecRegexp = /^\s*([D ])([E ])([VAS])([S ])([D ])([T ]) ([^ ]+) +(.*)$/;
var ffCodecRegexp = /^\s*([D\.])([E\.])([VAS])([I\.])([L\.])([S\.]) ([^ ]+) +(.*)$/;
var ffEncodersRegexp = /\(encoders:([^\)]+)\)/;
var ffDecodersRegexp = /\(decoders:([^\)]+)\)/;
var encodersRegexp = /^\s*([VAS\.])([F\.])([S\.])([X\.])([B\.])([D\.]) ([^ ]+) +(.*)$/;
var formatRegexp = /^\s*([D ])([E ]) ([^ ]+) +(.*)$/;
var lineBreakRegexp = /\r\n|\r|\n/;
var filterRegexp = /^(?: [T\.][S\.][C\.] )?([^ ]+) +(AA?|VV?|\|)->(AA?|VV?|\|) +(.*)$/;

var cache = {};

module.exports = function(proto) {
  /**
   * Manually define the ffmpeg binary full path.
   *
   * @method FfmpegCommand#setFfmpegPath
   *
   * @param {String} ffmpegPath The full path to the ffmpeg binary.
   * @return FfmpegCommand
   */
  proto.setFfmpegPath = function(ffmpegPath) {
    cache.ffmpegPath = ffmpegPath;
    return this;
  };

  /**
   * Manually define the ffprobe binary full path.
   *
   * @method FfmpegCommand#setFfprobePath
   *
   * @param {String} ffprobePath The full path to the ffprobe binary.
   * @return FfmpegCommand
   */
  proto.setFfprobePath = function(ffprobePath) {
    cache.ffprobePath = ffprobePath;
    return this;
  };

  /**
   * Manually define the flvtool2/flvmeta binary full path.
   *
   * @method FfmpegCommand#setFlvtoolPath
   *
   * @param {String} flvtool The full path to the flvtool2 or flvmeta binary.
   * @return FfmpegCommand
   */
  proto.setFlvtoolPath = function(flvtool) {
    cache.flvtoolPath = flvtool;
    return this;
  };

  /**
   * Forget executable paths
   *
   * (only used for testing purposes)
   *
   * @method FfmpegCommand#_forgetPaths
   * @private
   */
  proto._forgetPaths = function() {
    delete cache.ffmpegPath;
    delete cache.ffprobePath;
    delete cache.flvtoolPath;
  };

  /**
   * Check for ffmpeg availability
   *
   * If the FFMPEG_PATH environment variable is set, try to use it.
   * If it is unset or incorrect, try to find ffmpeg in the PATH instead.
   *
   * @method FfmpegCommand#_getFfmpegPath
   * @param {Function} callback callback with signature (err, path)
   * @private
   */
  proto._getFfmpegPath = function(callback) {
    if ('ffmpegPath' in cache) {
      return callback(null, cache.ffmpegPath);
    }

    async.waterfall([
      // Try FFMPEG_PATH
      function(cb) {
        if (process.env.FFMPEG_PATH) {
          fs.exists(process.env.FFMPEG_PATH, function(exists) {
            if (exists) {
              cb(null, process.env.FFMPEG_PATH);
            } else {
              cb(null, '');
            }
          });
        } else {
          cb(null, '');
        }
      },

      // Search in the PATH
      function(ffmpeg, cb) {
        if (ffmpeg.length) {
          return cb(null, ffmpeg);
        }

        utils.which('ffmpeg', function(err, ffmpeg) {
          cb(err, ffmpeg);
        });
      }
    ], function(err, ffmpeg) {
      if (err) {
        callback(err);
      } else {
        callback(null, cache.ffmpegPath = (ffmpeg || ''));
      }
    });
  };


  /**
   * Check for ffprobe availability
   *
   * If the FFPROBE_PATH environment variable is set, try to use it.
   * If it is unset or incorrect, try to find ffprobe in the PATH instead.
   * If this still fails, try to find ffprobe in the same directory as ffmpeg.
   *
   * @method FfmpegCommand#_getFfprobePath
   * @param {Function} callback callback with signature (err, path)
   * @private
   */
  proto._getFfprobePath = function(callback) {
    var self = this;

    if ('ffprobePath' in cache) {
      return callback(null, cache.ffprobePath);
    }

    async.waterfall([
      // Try FFPROBE_PATH
      function(cb) {
        if (process.env.FFPROBE_PATH) {
          fs.exists(process.env.FFPROBE_PATH, function(exists) {
            cb(null, exists ? process.env.FFPROBE_PATH : '');
          });
        } else {
          cb(null, '');
        }
      },

      // Search in the PATH
      function(ffprobe, cb) {
        if (ffprobe.length) {
          return cb(null, ffprobe);
        }

        utils.which('ffprobe', function(err, ffprobe) {
          cb(err, ffprobe);
        });
      },

      // Search in the same directory as ffmpeg
      function(ffprobe, cb) {
        if (ffprobe.length) {
          return cb(null, ffprobe);
        }

        self._getFfmpegPath(function(err, ffmpeg) {
          if (err) {
            cb(err);
          } else if (ffmpeg.length) {
            var name = utils.isWindows ? 'ffprobe.exe' : 'ffprobe';
            var ffprobe = path.join(path.dirname(ffmpeg), name);
            fs.exists(ffprobe, function(exists) {
              cb(null, exists ? ffprobe : '');
            });
          } else {
            cb(null, '');
          }
        });
      }
    ], function(err, ffprobe) {
      if (err) {
        callback(err);
      } else {
        callback(null, cache.ffprobePath = (ffprobe || ''));
      }
    });
  };


  /**
   * Check for flvtool2/flvmeta availability
   *
   * If the FLVTOOL2_PATH or FLVMETA_PATH environment variable are set, try to use them.
   * If both are either unset or incorrect, try to find flvtool2 or flvmeta in the PATH instead.
   *
   * @method FfmpegCommand#_getFlvtoolPath
   * @param {Function} callback callback with signature (err, path)
   * @private
   */
   proto._getFlvtoolPath = function(callback) {
    if ('flvtoolPath' in cache) {
      return callback(null, cache.flvtoolPath);
    }

    async.waterfall([
      // Try FLVMETA_PATH
      function(cb) {
        if (process.env.FLVMETA_PATH) {
          fs.exists(process.env.FLVMETA_PATH, function(exists) {
            cb(null, exists ? process.env.FLVMETA_PATH : '');
          });
        } else {
          cb(null, '');
        }
      },

      // Try FLVTOOL2_PATH
      function(flvtool, cb) {
        if (flvtool.length) {
          return cb(null, flvtool);
        }

        if (process.env.FLVTOOL2_PATH) {
          fs.exists(process.env.FLVTOOL2_PATH, function(exists) {
            cb(null, exists ? process.env.FLVTOOL2_PATH : '');
          });
        } else {
          cb(null, '');
        }
      },

      // Search for flvmeta in the PATH
      function(flvtool, cb) {
        if (flvtool.length) {
          return cb(null, flvtool);
        }

        utils.which('flvmeta', function(err, flvmeta) {
          cb(err, flvmeta);
        });
      },

      // Search for flvtool2 in the PATH
      function(flvtool, cb) {
        if (flvtool.length) {
          return cb(null, flvtool);
        }

        utils.which('flvtool2', function(err, flvtool2) {
          cb(err, flvtool2);
        });
      },
    ], function(err, flvtool) {
      if (err) {
        callback(err);
      } else {
        callback(null, cache.flvtoolPath = (flvtool || ''));
      }
    });
  };


  /**
   * A callback passed to {@link FfmpegCommand#availableFilters}.
   *
   * @callback FfmpegCommand~filterCallback
   * @param {Error|null} err error object or null if no error happened
   * @param {Object} filters filter object with filter names as keys and the following
   *   properties for each filter:
   * @param {String} filters.description filter description
   * @param {String} filters.input input type, one of 'audio', 'video' and 'none'
   * @param {Boolean} filters.multipleInputs whether the filter supports multiple inputs
   * @param {String} filters.output output type, one of 'audio', 'video' and 'none'
   * @param {Boolean} filters.multipleOutputs whether the filter supports multiple outputs
   */

  /**
   * Query ffmpeg for available filters
   *
   * @method FfmpegCommand#availableFilters
   * @category Capabilities
   * @aliases getAvailableFilters
   *
   * @param {FfmpegCommand~filterCallback} callback callback function
   */
  proto.availableFilters =
  proto.getAvailableFilters = function(callback) {
    if ('filters' in cache) {
      return callback(null, cache.filters);
    }

    this._spawnFfmpeg(['-filters'], { captureStdout: true }, function (err, stdout) {
      if (err) {
        return callback(err);
      }

      var lines = stdout.split('\n');
      var data = {};
      var types = { A: 'audio', V: 'video', '|': 'none' };

      lines.forEach(function(line) {
        var match = line.match(filterRegexp);
        if (match) {
          data[match[1]] = {
            description: match[4],
            input: types[match[2].charAt(0)],
            multipleInputs: match[2].length > 1,
            output: types[match[3].charAt(0)],
            multipleOutputs: match[3].length > 1
          };
        }
      });

      callback(null, cache.filters = data);
    });
  };


  /**
   * A callback passed to {@link FfmpegCommand#availableCodecs}.
   *
   * @callback FfmpegCommand~codecCallback
   * @param {Error|null} err error object or null if no error happened
   * @param {Object} codecs codec object with codec names as keys and the following
   *   properties for each codec (more properties may be available depending on the
   *   ffmpeg version used):
   * @param {String} codecs.description codec description
   * @param {Boolean} codecs.canDecode whether the codec is able to decode streams
   * @param {Boolean} codecs.canEncode whether the codec is able to encode streams
   */

  /**
   * Query ffmpeg for available codecs
   *
   * @method FfmpegCommand#availableCodecs
   * @category Capabilities
   * @aliases getAvailableCodecs
   *
   * @param {FfmpegCommand~codecCallback} callback callback function
   */
  proto.availableCodecs =
  proto.getAvailableCodecs = function(callback) {
    if ('codecs' in cache) {
      return callback(null, cache.codecs);
    }

    this._spawnFfmpeg(['-codecs'], { captureStdout: true }, function(err, stdout) {
      if (err) {
        return callback(err);
      }

      var lines = stdout.split(lineBreakRegexp);
      var data = {};

      lines.forEach(function(line) {
        var match = line.match(avCodecRegexp);
        if (match && match[7] !== '=') {
          data[match[7]] = {
            type: { 'V': 'video', 'A': 'audio', 'S': 'subtitle' }[match[3]],
            description: match[8],
            canDecode: match[1] === 'D',
            canEncode: match[2] === 'E',
            drawHorizBand: match[4] === 'S',
            directRendering: match[5] === 'D',
            weirdFrameTruncation: match[6] === 'T'
          };
        }

        match = line.match(ffCodecRegexp);
        if (match && match[7] !== '=') {
          var codecData = data[match[7]] = {
            type: { 'V': 'video', 'A': 'audio', 'S': 'subtitle' }[match[3]],
            description: match[8],
            canDecode: match[1] === 'D',
            canEncode: match[2] === 'E',
            intraFrameOnly: match[4] === 'I',
            isLossy: match[5] === 'L',
            isLossless: match[6] === 'S'
          };

          var encoders = codecData.description.match(ffEncodersRegexp);
          encoders = encoders ? encoders[1].trim().split(' ') : [];

          var decoders = codecData.description.match(ffDecodersRegexp);
          decoders = decoders ? decoders[1].trim().split(' ') : [];

          if (encoders.length || decoders.length) {
            var coderData = {};
            utils.copy(codecData, coderData);
            delete coderData.canEncode;
            delete coderData.canDecode;

            encoders.forEach(function(name) {
              data[name] = {};
              utils.copy(coderData, data[name]);
              data[name].canEncode = true;
            });

            decoders.forEach(function(name) {
              if (name in data) {
                data[name].canDecode = true;
              } else {
                data[name] = {};
                utils.copy(coderData, data[name]);
                data[name].canDecode = true;
              }
            });
          }
        }
      });

      callback(null, cache.codecs = data);
    });
  };


  /**
   * A callback passed to {@link FfmpegCommand#availableEncoders}.
   *
   * @callback FfmpegCommand~encodersCallback
   * @param {Error|null} err error object or null if no error happened
   * @param {Object} encoders encoders object with encoder names as keys and the following
   *   properties for each encoder:
   * @param {String} encoders.description codec description
   * @param {Boolean} encoders.type "audio", "video" or "subtitle"
   * @param {Boolean} encoders.frameMT whether the encoder is able to do frame-level multithreading
   * @param {Boolean} encoders.sliceMT whether the encoder is able to do slice-level multithreading
   * @param {Boolean} encoders.experimental whether the encoder is experimental
   * @param {Boolean} encoders.drawHorizBand whether the encoder supports draw_horiz_band
   * @param {Boolean} encoders.directRendering whether the encoder supports direct encoding method 1
   */

  /**
   * Query ffmpeg for available encoders
   *
   * @method FfmpegCommand#availableEncoders
   * @category Capabilities
   * @aliases getAvailableEncoders
   *
   * @param {FfmpegCommand~encodersCallback} callback callback function
   */
  proto.availableEncoders =
  proto.getAvailableEncoders = function(callback) {
    if ('encoders' in cache) {
      return callback(null, cache.encoders);
    }

    this._spawnFfmpeg(['-encoders'], { captureStdout: true }, function(err, stdout) {
      if (err) {
        return callback(err);
      }

      var lines = stdout.split(lineBreakRegexp);
      var data = {};

      lines.forEach(function(line) {
        var match = line.match(encodersRegexp);
        if (match && match[7] !== '=') {
          data[match[7]] = {
            type: { 'V': 'video', 'A': 'audio', 'S': 'subtitle' }[match[1]],
            description: match[8],
            frameMT: match[2] === 'F',
            sliceMT: match[3] === 'S',
            experimental: match[4] === 'X',
            drawHorizBand: match[5] === 'B',
            directRendering: match[6] === 'D'
          };
        }
      });

      callback(null, cache.encoders = data);
    });
  };


  /**
   * A callback passed to {@link FfmpegCommand#availableFormats}.
   *
   * @callback FfmpegCommand~formatCallback
   * @param {Error|null} err error object or null if no error happened
   * @param {Object} formats format object with format names as keys and the following
   *   properties for each format:
   * @param {String} formats.description format description
   * @param {Boolean} formats.canDemux whether the format is able to demux streams from an input file
   * @param {Boolean} formats.canMux whether the format is able to mux streams into an output file
   */

  /**
   * Query ffmpeg for available formats
   *
   * @method FfmpegCommand#availableFormats
   * @category Capabilities
   * @aliases getAvailableFormats
   *
   * @param {FfmpegCommand~formatCallback} callback callback function
   */
  proto.availableFormats =
  proto.getAvailableFormats = function(callback) {
    if ('formats' in cache) {
      return callback(null, cache.formats);
    }

    // Run ffmpeg -formats
    this._spawnFfmpeg(['-formats'], { captureStdout: true }, function (err, stdout) {
      if (err) {
        return callback(err);
      }

      // Parse output
      var lines = stdout.split(lineBreakRegexp);
      var data = {};

      lines.forEach(function(line) {
        var match = line.match(formatRegexp);
        if (match) {
          match[3].split(',').forEach(function(format) {
            if (!(format in data)) {
              data[format] = {
                description: match[4],
                canDemux: false,
                canMux: false
              };
            }

            if (match[1] === 'D') {
              data[format].canDemux = true;
            }
            if (match[2] === 'E') {
              data[format].canMux = true;
            }
          });
        }
      });

      callback(null, cache.formats = data);
    });
  };


  /**
   * Check capabilities before executing a command
   *
   * Checks whether all used codecs and formats are indeed available
   *
   * @method FfmpegCommand#_checkCapabilities
   * @param {Function} callback callback with signature (err)
   * @private
   */
  proto._checkCapabilities = function(callback) {
    var self = this;
    async.waterfall([
      // Get available formats
      function(cb) {
        self.availableFormats(cb);
      },

      // Check whether specified formats are available
      function(formats, cb) {
        var unavailable;

        // Output format(s)
        unavailable = self._outputs
          .reduce(function(fmts, output) {
            var format = output.options.find('-f', 1);
            if (format) {
              if (!(format[0] in formats) || !(formats[format[0]].canMux)) {
                fmts.push(format);
              }
            }

            return fmts;
          }, []);

        if (unavailable.length === 1) {
          return cb(new Error('Output format ' + unavailable[0] + ' is not available'));
        } else if (unavailable.length > 1) {
          return cb(new Error('Output formats ' + unavailable.join(', ') + ' are not available'));
        }

        // Input format(s)
        unavailable = self._inputs
          .reduce(function(fmts, input) {
            var format = input.options.find('-f', 1);
            if (format) {
              if (!(format[0] in formats) || !(formats[format[0]].canDemux)) {
                fmts.push(format[0]);
              }
            }

            return fmts;
          }, []);

        if (unavailable.length === 1) {
          return cb(new Error('Input format ' + unavailable[0] + ' is not available'));
        } else if (unavailable.length > 1) {
          return cb(new Error('Input formats ' + unavailable.join(', ') + ' are not available'));
        }

        cb();
      },

      // Get available codecs
      function(cb) {
        self.availableEncoders(cb);
      },

      // Check whether specified codecs are available and add strict experimental options if needed
      function(encoders, cb) {
        var unavailable;

        // Audio codec(s)
        unavailable = self._outputs.reduce(function(cdcs, output) {
          var acodec = output.audio.find('-acodec', 1);
          if (acodec && acodec[0] !== 'copy') {
            if (!(acodec[0] in encoders) || encoders[acodec[0]].type !== 'audio') {
              cdcs.push(acodec[0]);
            }
          }

          return cdcs;
        }, []);

        if (unavailable.length === 1) {
          return cb(new Error('Audio codec ' + unavailable[0] + ' is not available'));
        } else if (unavailable.length > 1) {
          return cb(new Error('Audio codecs ' + unavailable.join(', ') + ' are not available'));
        }

        // Video codec(s)
        unavailable = self._outputs.reduce(function(cdcs, output) {
          var vcodec = output.video.find('-vcodec', 1);
          if (vcodec && vcodec[0] !== 'copy') {
            if (!(vcodec[0] in encoders) || encoders[vcodec[0]].type !== 'video') {
              cdcs.push(vcodec[0]);
            }
          }

          return cdcs;
        }, []);

        if (unavailable.length === 1) {
          return cb(new Error('Video codec ' + unavailable[0] + ' is not available'));
        } else if (unavailable.length > 1) {
          return cb(new Error('Video codecs ' + unavailable.join(', ') + ' are not available'));
        }

        cb();
      }
    ], callback);
  };
};
