require 'forwardable'
require 'net/http'
require 'mediainfo/errors'
require 'mediainfo/tracks'
require 'mediainfo/string'

module MediaInfo

  def self.which(cmd)
    exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
    ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
      exts.each { |ext|
        exe = File.join(path, "#{cmd}#{ext}")
        return exe if File.executable?(exe) && !File.directory?(exe)
      }
    end
    return nil
  end

  # Allow user to set custom mediainfo_path with ENV['MEDIAINFO_PATH']
  def self.location
    if ENV['MEDIAINFO_PATH'].nil?
      mediainfo_location = which('mediainfo')
    else
      mediainfo_location = ENV['MEDIAINFO_PATH']
    end
    raise EnvironmentError, "MediaInfo binary cannot be found. Are you sure mediainfo is installed?" if which('mediainfo').nil?
    raise EnvironmentError, "MediaInfo path you provided cannot be found. Please check your mediainfo installation location..." unless ::File.exist? mediainfo_location
    return mediainfo_location
  end

  # Allow collection of MediaInfo version details
  def self.version
    version ||= `#{location} --Version`[/v([\d.]+)/, 1]
    # Ensure MediaInfo isn't buggy and returns something
    raise UnknownVersionError, 'Unable to determine mediainfo version. ' + "We tried: #{location} --Version." +
          'Set MediaInfo.path = \'/full/path/of/mediainfo\' if it is not in your PATH.' unless version
    # Ensure you're not using an old version of MediaInfo
    if version < '0.7.25'
      raise IncompatibleVersionError, "Your version of mediainfo, #{version}, " +
          'is not compatible with this gem. >= 0.7.25 required.'
    else
      @version = version
    end

  end

  def self.xml_parser
    ENV['MEDIAINFO_XML_PARSER'].nil? || ENV['MEDIAINFO_XML_PARSER'].to_s.strip.empty? ? xml_parser = 'rexml/document' : xml_parser = ENV['MEDIAINFO_XML_PARSER']
    begin
      require xml_parser
    rescue Gem::LoadError => ex
      raise Gem::LoadError, "Your specified XML parser, #{xml_parser.inspect}, could not be loaded: #{ex.message}"
    end
    return xml_parser
  end

  def self.run(input = nil)
    raise ArgumentError, 'Your input cannot be blank.' if input.nil?
    command = "#{location} #{input} --Output=XML 2>&1"
    raw_response = `#{command}`
    unless $? == 0
      raise ExecutionError, "Execution of '#{command}' failed. #{raw_response.inspect}"
    end
    return raw_response
  end

  def self.from(input)
    return from_uri(input) if input.is_a?(URI)
    return from_string(input) if input.is_a?(String)
    raise BadInputError
  end

  def self.from_string(input)
    return from_xml(input) if input.include?('<?xml')
    return from_link(input) if input.include?('://') && input =~ URI::regexp
    return from_local_file(input) if input.match(/[^\\]*\.\w+$/)
    raise BadInputError
  end

  def self.from_xml(input)
    MediaInfo::Tracks.new(input)
  end

  def self.from_local_file(input)
    absolute_path = File.expand_path(input) # turns relative to absolute path

    raise ArgumentError, 'You must include a file location.' if absolute_path.nil?
    raise ArgumentError, "need a path to a video file, #{absolute_path} does not exist" unless File.exist?(absolute_path)

    return from_xml(File.open(absolute_path).read) if absolute_path.match(/[^\\]*\.(xml)$/)
    MediaInfo::Tracks.new(MediaInfo.run(absolute_path.shell_escape_double_quotes))
  end

  def self.from_link(input)
    from_uri(URI(input))
  end

  def self.from_uri(input)
    http = Net::HTTP.new(input.host, input.port) # Check if input is valid
    request = Net::HTTP::Head.new(input.request_uri) # Only grab the Headers to be sure we don't try and download the whole file
    http.use_ssl = true if input.is_a? URI::HTTPS # For https support
    http_request = http.request(request)
    raise RemoteUrlError, "HTTP call to #{input} is not working : #{http_request.value}" unless http_request.is_a?(Net::HTTPOK)
    MediaInfo::Tracks.new(MediaInfo.run(URI.escape(input.to_s)))
  end

  def self.set_singleton_method(object,name,parameters)
    # Handle parameters with invalid characters (instance_variable_set throws error)
    name.gsub!('.','_') if name.include?('.') ## period in name
    name.downcase!
    # Create singleton_method
    object.instance_variable_set("@#{name}",parameters)
    object.define_singleton_method name do
      object.instance_variable_get "@#{name}"
    end
  end

end # end Module