require 'cfpropertylist'
require 'json'
require 'net/http'
require 'pathname'
require 'zip/zip'
require 'zip/zipfilesystem'

module AppStore; end

module AppStore::Emigrant

  # Represents a single iTunes mobile application
  class App

    # List of valid extensions for an application
    VALID_EXTENSIONS = [
      '.ipa'
    ]

    # Regular expression to match a version number in filenames
    FILENAME_VERSION_REGEX = Regexp.new('([0-9.]+)(?:' + VALID_EXTENSIONS.join('|').gsub!('.', '\.') + ')')

    attr_reader :path
    attr_writer :clouddata

    # Initializes application from given path
    def initialize path
      @path = Pathname.new path
      @path = @path.expand_path unless @path.absolute?

      # Ensure application exists
      unless @path.file?
        raise DoesNotExist, "Given path is not a valid application: #{@path}"
      end

      # Ensure application has valid extension
      unless VALID_EXTENSIONS.include? @path.extname
        raise Invalid, "Given application does not have a valid extension: #{@path}"
      end

      @metadata = nil
      @clouddata = nil
    end

    # Filename of this application (including extension)
    def filename
      unless @filename
        @filename = @path.basename.to_s
      end

      @filename
    end

    # Unique application id
    def id
      metadata['itemId'] rescue nil
    end

    # Name of this application
    def name
      metadata['itemName'] rescue nil
    end

    # Whether this application is valid (validates metadata, id and name)
    def valid?
      metadata && id && name rescue false
    end

    # Version of this application
    def version
      unless @version

        # Extract version information (if available)
        @version = metadata['bundleShortVersionString'] || metadata['bundleVersion'] rescue nil

        # Otherwise, use the filename
        unless @version
          @version = filename[FILENAME_VERSION_REGEX, 1]
        end

      end

      @version
    end

    # Property list name
    def plist
      Pathname.new(filename).basename('.ipa').to_s + '.plist'
    end

    # Whether this application's metadata is cached
    def cached?
      Cache.has? plist
    end

    # Forcefully caches this application's metadata
    def cache!
      metadata
    end

    # Lazily loads local metadata for this application from its iTunesMetadata.plist
    def metadata
      unless @metadata

        unless cached?
          begin
            Zip::ZipFile.open(@path) do |zip|
              zip.extract('iTunesMetadata.plist', Cache.path_to(plist))
            end
          rescue Zip::ZipError => e
            raise Invalid, e.message
          end
        end

        @metadata = CFPropertyList.native_types(CFPropertyList::List.new(:file => Cache.path_to(plist)).value)
      end

      @metadata
    end

    # Lazily queries Apple's iTunes Store API for latest cloud data
    # Note: Clouddata may be nil if the application was removed from the store
    def clouddata
      unless @clouddata
        response = Net::HTTP.get('itunes.apple.com', '/lookup?id=' + id.to_s)
        @clouddata = JSON.parse(response)['results'].first
      end

      @clouddata
    end

    # Version available in the cloud
    def cloudversion
      clouddata && clouddata['version']
    end

    # Whether this application is outdated
    def outdated?
      return cloudversion && version != cloudversion
    end

    # Raised when an application does not exist
    class DoesNotExist < StandardError; end

    # Raised when an application is invalid (e.g non-valid extension)
    class Invalid < StandardError; end

  end

end