module Sprout
  
  class ToolTaskError < StandardError #:nodoc:
  end
  
  # The ToolTask provides some base functionality for any Command Line Interface (CLI) tool. 
  # It also provides support for GUI tools that you would like to expose from the
  # Command Line (Like the Flash Player for example).
  #
  # ToolTask extends Rake::FileTask, and should be thought of in the same way. 
  # Martin Fowler did a much better job of describing Rake and specifically FileTasks than 
  # I can in his (now classic) Rake article[http://martinfowler.com/articles/rake.html#FileTasks] from 2005.
  #
  # What this means is that most tool task instances should be named for the file that they will create.
  # For example, an Sprout::MXMLCTask instance should be named for the SWF that it will generate.
  #
  #   mxmlc 'bin/SomeProject.swf' => :corelib do |t|
  #     t.input                     = 'src/SomeProject.as'
  #     t.default_size              = '800 600'
  #   end
  #
  # In general, a tool task will only be executed if it's output file (name) does not exist or
  # if the output file is older than any file identified as a prerequisite.
  #
  # Many of the compiler tasks take advantage of this feature by opting out of unnecessary compilation.
  #
  # Subclasses can add and configure command line parameters by calling the protected add_param method
  # that is implemented on this class.
  #
  class ToolTask < Rake::FileTask
    @@preprocessed_tasks = Hash.new
    
    def self.add_preprocessed_task(name)
      @@preprocessed_tasks[name] = true
    end

    def self.has_preprocessed_task?(name)
      !@@preprocessed_tasks[name].nil?
    end

    def self.clear_preprocessed_tasks
      @@preprocessed_tasks.clear
    end
    
    def initialize(name, app) # :nodoc:
      super
      @preprocessed_path = nil
      @prepended_args    = nil
      @appended_args     = nil
      @default_gem_name  = nil
      @default_gem_path  = nil
      initialize_task
    end
    
    def self.define_task(args, &block)
      t = super
      if(t.is_a?(ToolTask))
        t.find_and_resolve_model
        yield t if block_given?
        t.define
        t.prepare
      end
      return t
    end
    
    # Full name of the sprout tool gem that this tool task will use. For example, the MXMLCTask
    # uses the sprout-flex3sdk-tool at the time of this writing, but will at some point 
    # change to use the sprout-flex3sdk-tool. You can combine this value with gem_version
    # in order to specify exactly which gem your tool task is executing.
    def gem_name
      return @gem_name ||= @default_gem_name
    end
    
    def gem_name=(name)
      @gem_name = name
    end

    # The exact gem version that you would like the ToolTask to execute. By default this value
    # should be nil and will download the latest version of the gem that is available unless
    # there is a version already installed on your system. 
    # 
    # This attribute could be an easy
    # way to update your local gem to the latest version without leaving your build file,
    # but it's primary purpose is to allow you to specify very specific versions of the tools
    # that your project depends on. This way your team can rest assured that they are all
    # working with the same tools.
    def gem_version
      return @gem_version ||= nil
    end
    
    def gem_version=(version)
      @gem_version = version
    end
    
    # The path inside the installed gem where an executable can be found. For the MXMLCTask, this
    # value is 'bin/mxmlc'.
    def gem_path
      return @gem_path ||= @default_gem_path
    end
    
    def each_param
      params.each do |param|
        yield param if block_given?
      end
    end
    
    # Create a string that can be turned into a file
    # that rdoc can parse to describe the customized
    # or generated task using param name, type and
    # description
    def to_rdoc
      result = ''
      parts = self.class.to_s.split('::')
      class_name = parts.pop
      module_count = 0
      while(module_name = parts.shift)
        result << "module #{module_name}\n"
        module_count += 1
      end
      
      result << "class #{class_name} < ToolTask\n"

      params.each do |param|
        result << param.to_rdoc
      end

      while((module_count -= 1) >= 0)
        result << "end\nend\n"
      end

      return result
    end

    # Arguments to be prepended in front of the command line output
    def prepended_args=(args)
      @prepended_args = args
    end
    
    # Returns arguments that were prepended in front of the command line output
    def prepended_args
      @prepended_args
    end
    
    # Arguments to appended at the end of the command line output
    def appended_args=(args)
      @appended_args = args
    end
    
    # Returns arguments that were appended at the end of the command line output
    def appended_args
      @appended_args
    end
    
    # Command line arguments to execute preprocessor.
    # The preprocessor execution should accept text via STDIN and return its processed content via STDOUT.
    #
    # In the following example, the +MXMLCTask+ has been configured to use the C preprocessor (cpp) and
    # place the processed output into a +_preprocessed+ folder, instead of the hidden default folder at 
    # .preprocessed.
    #
    # One side effect of the cpp tool is that it adds 2 carriage returns to the top of any processed files,
    # so we have simply piped its output to the tail command which then strips those carriage returns from
    # all files - which retains accurate line numbers for any compiler error messages.
    #
    #   mxmlc 'bin/SomeProject.swf' => :corelib do |t|
    #     t.input                     = 'src/SomeProject.as'
    #     t.default_size              = '800 600'
    #     t.preprocessor              = 'cpp -D__DEBUG=true -P - - | tail -c +3'
    #     t.preprocessed_path         = '_preprocessed'
    #   end
    #
    # Any source files found in this example project can now take advantage of any tools, macros or syntax
    # available to CPP. For example, the +__DEBUG+ variable is now defined and can be accessed in ActionScript
    # source code as follows:
    #
    #   public static const DEBUG:Boolean = __DEBUG;
    #
    # Any commandline tool identified on this attribute will be provided the content of each file on STDIN and 
    # whatever it returns to STDOUT will be written into the +preprocessed_path+. This means that we can 
    # take advantage of the entire posix tool chain by piping inputs and outputs from one tool to another.
    # Whatever the last tool returns will be handed off to the concrete compiler.
    def preprocessor=(preprocessor)
      @preprocessor = preprocessor
    end

    def preprocessor
      @preprocessor
    end

    # Path where preprocessed files are stored. Defaults to '.preprocessed'
    def preprocessed_path=(preprocessed_path)
      @preprocessed_path = preprocessed_path
    end
    
    def preprocessed_path
      @preprocessed_path ||= '.preprocessed'
    end
    
    def display_preprocess_message # :nodoc:
      if(!preprocessor.nil?)
        puts ">> Preprocessed text files in: #{File.join(Dir.pwd, preprocessed_path)} with #{preprocessor}"
      end
    end
    
    def execute(*args)
      display_preprocess_message
      exe = Sprout.get_executable(gem_name, gem_path, gem_version)
      User.execute(exe, to_shell)
    end
    
    # Create a string that represents this configured tool for shell execution
    def to_shell
      return @to_shell_proc.call(self) if(!@to_shell_proc.nil?)

      result = []
      result << @prepended_args unless @prepended_args.nil?
      params.each do |param|
        if(param.visible?)
          result << param.to_shell
        end
      end
      result << @appended_args unless @appended_args.nil?
      return result.join(' ')
    end

    # An Array of all parameters that have been added to this Tool.
    def params
      @params ||= []
    end
    
    # Called after initialize and define, usually subclasses should
    # only override define.
    def prepare
      # Get each added param to inject prerequisites as necessary
      params.each do |param|
        param.prepare
      end
      prepare_prerequisites
    end
    
    def prepare_prerequisites
      # Ensure there are no duplicates in the prerequisite collection
      @prerequisites = prerequisites.uniq
    end
    
    def define
      resolve_libraries(prerequisites)
    end
    
    # Look for a ToolTaskModel in the list
    # of prerequisites. If found, apply
    # any applicable params to self...
    def find_and_resolve_model
      prerequisites.each do |prereq|
        instance = Rake::application[prereq]
        if(instance.is_a?(ToolTaskModel))
          resolve_model(instance)
        end
      end
    end

    # The default file expression to append to each PathParam
    # in order to build file change prerequisites.
    # 
    # Defaults to '/**/**/*'
    #
    def default_file_expression
      @default_file_expression ||= '/**/**/*'
    end
    
    protected
    
    def initialize_task
    end

    def validate
      params.each do |param|
        param.validate
      end
    end

    # +add_param+ is the workhorse of the ToolTask.
    # This method is used to add new shell parameters to the task.
    # +name+ is a symbol or string that represents the parameter that you would like to add
    # such as :debug or :source_path.
    # +type+ is usually sent as a Ruby symbol and can be one of the following:
    #
    # [:string]   Any string value
    # [:boolean]  true or false
    # [:number]   Any number
    # [:file]     Path to a file
    # [:url]      Basic URL
    # [:path]     Path to a directory
    # [:files]    Collection of files
    # [:paths]    Collection of directories
    # [:strings]  Collection of arbitrary strings
    # [:urls]     Collection of URLs
    #
    # Be sure to check out the Sprout::TaskParam class to learn more about
    # block editing the parameters.
    #
    # Once parameters have been added using the +add_param+ method, clients
    # can set and get those parameters from the newly created task.
    #
    def add_param(name, type, &block) # :yields: Sprout::TaskParam
      name = name.to_s

      # First ensure the named accessor doesn't yet exist...
      if(param_hash[name])
        raise ToolTaskError.new("TaskBase.add_param called with existing parameter name: #{name}")
      end

      param = create_param(type)
      param.init do |p|
        p.belongs_to = self
        p.name = name
        p.type = type
        yield p if block_given?
      end

      param_hash[name] = param
      params << param
    end

    # Alias an existing parameter with another name. For example, the 
    # existing parameter :source_path might be given an alias '-sp' as follows:
    #
    #   add_param_alias(:sp, :source_path)
    #
    # Alias parameters cannot be configured differently from the parameter
    # that they alias
    #
    def add_param_alias(name, other_param)
      if(param_hash.has_key? other_param.to_s)
        param_hash[name.to_s] = param_hash[other_param.to_s]
      else
        raise ToolTaskError.new("TaskBase.add_param_alis called with")
      end
    end

    def create_param(type)
      return eval("#{type.to_s.capitalize}Param.new")
    end
    
    def param_hash
      @param_hash ||= {}
    end

    def respond_to?(name)
      result = super
      if(!result)
        result = param_hash.has_key? name.to_s
      end
      return result
    end

    def clean_name(name)
      name.gsub(/=$/, '')
    end

    def method_missing(name, *args)
      name = name.to_s
      cleaned = clean_name(name)
      if(!respond_to?(cleaned))
        raise NoMethodError.new("undefined method '#{name}' for #{self.class}", name)
      end
      param = param_hash[cleaned]

      matched = name =~ /=$/
      if(matched)
        param.value = args.shift
      elsif(param)
        param.value
      else
        raise ToolTaskError.new("method_missing called with undefined parameter [#{name}]")
      end
    end

    # Iterate over all prerequisites looking for any
    # that are a LibraryTask.
    # Concrete ToolTask implementations should
    # override resolve_library in order to add
    # the library sources or binaries appropriately.
    def resolve_libraries(prerequisites)
      prerequisites.each do |prereq|
        instance = Rake::application[prereq]
        if(instance.is_a?(LibraryTask))
          resolve_library(instance)
        end
      end
    end
    
    # Concrete ToolTasks should override this method
    # and add any dependent libraries appropriately
    def resolve_library(library_task)
    end
    
    def resolve_model(model)
      model.each_attribute do |key, value|
        if(respond_to? key)
          self.send("#{key}=", value)
        end
      end
    end
    
    # If the provided path contains spaces, wrap it in quotes so that
    # shell tools won't choke on the spaces
    def clean_path(path)
      if(path.index(' '))
        path = %{"#{path}"}
      end
      return path
    end
    
  end

  #######################################################
  # Parameter Implementations
  
  # The base class for all ToolTask parameters. This class is extended by a variety
  # of concrete implementations.
  #
  # At the time of this writing, only the :boolean TaskParam modifies the interface by
  # adding the +show_on_false+ attribute.
  #
  # Some other helpful features are as follows:
  #
  # :file, :files, :path and :paths will all add any items that have been added to
  # their values as file task prerequisites. This is especially helpful when writing
  # rake tasks for Command Line Interface (CLI) compilers.
  #
  class TaskParam
    attr_accessor :belongs_to
    attr_accessor :description
    attr_accessor :hidden_name
    attr_accessor :hidden_value
    attr_accessor :name
    attr_accessor :preprocessable
    attr_accessor :required
    attr_accessor :type
    attr_accessor :validator
    attr_accessor :visible

    attr_writer   :prefix
    attr_writer   :value
    attr_writer   :delimiter
    attr_writer   :shell_name
    attr_writer   :to_shell_proc

    # Set the file_expression (blob) to append to each path
    # in order to build the prerequisites FileList.
    #
    # Defaults to parent ToolTask.default_file_expression
    attr_writer :file_expression

    def init
      yield self if block_given?
    end
    
    # By default, ToolParams only appear in the shell
    # output when they are not nil
    def visible?
      @visible ||= value
    end
    
    def required?
      (required == true)
    end
    
    def validate
      if(required? && !visible?)
        raise ToolTaskError.new("#{name} is required and must not be nil")
      end
    end
    
    def prepare
      prepare_prerequisites
    end
    
    def prepare_prerequisites
    end
    
    # Should the param name be hidden from the shell?
    # Used for params like 'input' on mxmlc
    def hidden_name?
      @hidden_name ||= false
    end
    
    # Should the param value be hidden from the shell?
    # Usually used for Boolean toggles like '-debug'
    def hidden_value?
      @hidden_value ||= false
    end
    
    # Leading character for each parameter
    # Can sometimes be an empty string,
    # other times it's a double dash '--'
    # but usually it's just a single dash '-'
    def prefix
      @prefix ||= '-'
    end
    
    def value
      @value
    end

    def shell_value
      value.to_s
    end

    def file_expression # :nodoc:
      @file_expression ||= belongs_to.default_file_expression
    end

    # ToolParams join their name/value pair with an
    # equals sign by default, this can be modified 
    # To a space or whatever you wish
    def delimiter
      @delimiter ||= '='
    end
    
    # Return the name with a single leading dash
    # and underscores replaced with dashes
    def shell_name
      @shell_name ||= prefix + name.split('_').join('-')
    end

    def to_shell
      if(!@to_shell_proc.nil?)
        return @to_shell_proc.call(self)
      elsif(hidden_name?)
        return shell_value
      elsif(hidden_value?)
        return shell_name
      else
        return "#{shell_name}#{delimiter}#{shell_value}"
      end
    end
    
    # Create a string that can be turned into a file
    # that rdoc can parse to describe the customized
    # or generated task using param name, type and
    # description
    def to_rdoc
      result = ''
      parts = description.split("\n") unless description.nil?
      result << "# #{parts.join("\n# ")}\n" unless description.nil?
      result << "def #{name}=(#{type})\n  @#{name} = #{type}\nend\n\n"
      return result
    end

    protected
    
    def should_preprocess?
      return preprocessable && !belongs_to.preprocessor.nil?
    end
    
    def prepare_preprocessor_paths(paths)
      processed = []
      paths.each do |path|
        processed << prepare_preprocessor_path(path)
      end
      return processed
    end
    
    def prepare_preprocessor_files(files)
      processed = []
      files.each do |file|
        processed << prepare_preprocessor_file(file)
      end
      return processed
    end
    
    def cleaned_preprocessed_path(path)
      File.join(belongs_to.preprocessed_path, path.gsub('../', 'backslash/'))
    end
    
    def prepare_preprocessor_path(path)
      processed_path = cleaned_preprocessed_path(path)
      FileUtils.mkdir_p(processed_path)
      files = FileList[path + file_expression]
      files.each do |input_file|
        prepare_preprocessor_file(input_file)
      end
      
      return processed_path
    end
    
    def prepare_preprocessor_file(input_file)
      output_file = cleaned_preprocessed_path(input_file)
      setup_preprocessing_file_tasks(input_file, output_file)
      return output_file
    end
    
    def text_file?(file_name)
      [/\.as$/, /\.txt$/, /\.mxml$/, /\.xml$/, /\.js$/, /\.html$/, /\.htm$/].select do |regex|
        if (file_name.match(regex))
          return true
        end
      end.size > 0
    end
    
    def setup_preprocessing_file_tasks(input_file, output_file)
      return if(File.directory?(input_file))
      CLEAN.add(belongs_to.preprocessed_path) if(!CLEAN.index(belongs_to.preprocessed_path))
      
      # Only create the preprocessed action if one does not
      # already exist. There were many being created before...
        
      file input_file
      file output_file => input_file do
        # Couldn't return, b/c Rake complained...
        if(!ToolTask::has_preprocessed_task?(output_file))
          dir = File.dirname(output_file)
          if(!File.exists?(dir))
            FileUtils.mkdir_p(dir)
          end
        
          content = nil
          # Open the input file and read its content:
          File.open(input_file, 'r') do |readable|
            content = readable.read
          end
        
          # Preprocess the content if it's a known text file type:
          if(text_file?(input_file))
            content = preprocess_content(content, belongs_to.preprocessor, input_file)
          end
        
          # Write the content to the output file:
          File.open(output_file, 'w+') do |writable|
            writable.write(content)
          end

          ToolTask::add_preprocessed_task(output_file)
        end
      end
      
      belongs_to.prerequisites << output_file
    end
    
    def preprocess_content(content, statement, file_name)
      process = ProcessRunner.new(statement)
      process.puts(content)
      process.close_write
      result = process.read
      error = process.read_err
      if(error.size > 0)
        belongs_to.display_preprocess_message
        FileUtils.rm_rf(belongs_to.preprocessed_path)
        raise ExecutionError.new("[ERROR] Preprocessor failed on file #{file_name} #{error}")
      end
      process.kill
      Log.puts ">> Preprocessed and created: #{belongs_to.preprocessed_path}/#{file_name}"
      return result
    end
    
  end

  # Concrete param object for :string values
  class StringParam < TaskParam # :nodoc:

    def shell_value
      value.gsub(/ /, "\ ")
    end
  end

  # Concrete param object for :symbol values
  # like class names
  class SymbolParam < TaskParam # :nodoc:
  end

  # Concrete param object for :url values
  class UrlParam < TaskParam # :nodoc:
  end

  # Concrete param object for :number values
  class NumberParam < TaskParam # :nodoc:
  end

  # Concrete param object for :file values
  class FileParam < TaskParam # :nodoc:

    def prepare_prerequisites
      if(value && value != belongs_to.name.to_s)
        if(should_preprocess?)
          @value = prepare_preprocessor_file(value)
        else
          file value
          belongs_to.prerequisites << value
        end
      end
    end
  end

  # Concrete param object for :path values
  class PathParam < TaskParam # :nodoc:

    def prepare_prerequisites
      if(value && value != belongs_to.name.to_s)
        if should_preprocess?
          @value = prepare_preprocessor_path(value)
        else
          file value
          belongs_to.prerequisites << value
        end
      end
    end
  end

  # Concrete param object for :boolean values
  class BooleanParam < TaskParam # :nodoc:
    attr_writer :show_on_false
    
    def visible?
      @visible ||= value
      if(show_on_false)
        return true unless value
      else
        return @visible
      end
    end

    def show_on_false
      @show_on_false ||= false
    end
    
    def value
      @value ||= false
    end

  end

  # Concrete param object for collections of strings
  class StringsParam < TaskParam # :nodoc:

    def value=(val)
      if(val.is_a?(String))
        message = "The #{name} property is an Array, not a String. It looks like you may have used the assignment operator (=) where the append operator (<<) was expected."
        raise ToolTaskError.new(message)
      end
      @value = val
    end

    # Files lists are initialized to an empty array by default
    def value
      @value ||= []
    end

    # By default, the FilesParams will not appear in the shell
    # output if there are zero items in the collection
    def visible?
      @visible ||= (value && value.size > 0)   
    end

    # Default delimiter is +=
    # This is what will appear between each name/value pair as in:
    # "source_path+=src source_path+=test source_path+=lib"
    def delimiter
      @delimiter ||= "+="
    end
    
    # Returns a shell formatted string of the collection
    def to_shell
      return @to_shell_proc.call(self) if(!@to_shell_proc.nil?)

      result = []
      value.each do |str|
        result << "#{shell_name}#{delimiter}#{str}"
      end
      return result.join(' ')
    end
  end

  # Concrete param object for collections of symbols (like class names)
  class SymbolsParam < StringsParam # :nodoc:
  end

  # Concrete param object for collections of files
  class FilesParam < StringsParam # :nodoc:

    def prepare
      super
      usr = User.new
      path = nil
      value.each_index do |index|
        path = value[index]
        value[index] = usr.clean_path path
      end
    end

    def prepare_prerequisites
      if should_preprocess?
        @value = prepare_preprocessor_files(value)
      else
        value.each do |f|
          file f
          belongs_to.prerequisites << f
        end
      end
    end

  end

  # Concrete param object for collections of paths
  class PathsParam < FilesParam # :nodoc:

    def prepare_prerequisites
      if should_preprocess?
        @value = prepare_preprocessor_paths(value)
      else
        value.each do |path|
          files = FileList[path + file_expression]
          files.each do |f|
            file f
            belongs_to.prerequisites << f
          end
        end
      end
    end
    

  end

  # Concrete param object for collections of files
  class UrlsParam < StringsParam # :nodoc:
  end

end