require 'ostruct'

module YARD
  module Tags
    # The base directive class. Subclass this class to create a custom
    # directive, registering it with {Library.define_directive}. Directive
    # classes are executed via the {#call} method, which perform all directive
    # processing on the object.
    #
    # If processing occurs within a handler, the {#handler} attribute is
    # available to access more information about parsing context and state.
    # Handlers are only available when parsing from {Parser::SourceParser},
    # not when parsing directly from {DocstringParser}. If the docstring is
    # attached to an object declaration, {#object} will be set and available
    # to modify the generated code object directly. Note that both of these
    # attributes may be nil, and directives should test their existence
    # before attempting to use them.
    #
    # @abstract Subclasses should implement {#call}.
    # @see Library.define_directive
    # @since 0.8.0
    class Directive
      # @return [Tag] the meta-data tag containing data input to the directive
      attr_accessor :tag

      # Set this field to replace the directive definition inside of a docstring
      # with arbitrary text. For instance, the {MacroDirective} uses this field
      # to expand its macro data in place of the call to a +@!macro+.
      #
      # @return [String] the text to expand in the original docstring in place
      #   of this directive definition.
      # @return [nil] if no expansion should take place for this directive
      attr_accessor :expanded_text

      # @return [DocstringParser] the parser that is parsing all tag
      #   information out of the docstring
      attr_accessor :parser

      # @!attribute [r] object
      # @return [CodeObjects::Base, nil] the object the parent docstring is
      #   attached to. May be nil.
      def object; parser.object end

      # @!attribute [r] handler
      # @return [Handlers::Base, nil] the handler object the docstring parser
      #   might be attached to. May be nil. Only available when parsing
      #   through {Parser::SourceParser}.
      def handler; parser.handler end

      # @!endgroup

      # @param [Tag] tag the meta-data tag containing all input to the docstring
      # @param [DocstringParser] parser the docstring parser object
      def initialize(tag, parser)
        self.tag = tag
        self.parser = parser
        self.expanded_text = nil
      end

      # @!group Parser callbacks

      # Called when processing the directive. Subclasses should implement
      # this method to perform all functionality of the directive.
      #
      # @abstract implement this method to perform all data processing for
      #   the directive.
      # @return [void]
      def call; raise NotImplementedError end

      # Called after parsing all directives and tags in the docstring. Used
      # to perform any cleanup after all directives perform their main task.
      # @return [void]
      def after_parse; end

      protected :parser
    end

    # Ends a group listing definition. Group definition automatically end
    # when class or module blocks are closed, and defining a new group overrides
    # the last group definition, but occasionally you need to end the current
    # group to return to the default listing. Use {tag:!group} to begin a
    # group listing.
    #
    # @example
    #   class Controller
    #     # @!group Callbacks
    #
    #     def before_filter; end
    #     def after_filter; end
    #
    #     # @!endgroup
    #
    #     def index; end
    #   end
    # @see tag:!group
    # @since 0.6.0
    class EndGroupDirective < Directive
      def call
        return unless handler
        handler.extra_state.group = nil
      end
    end

    # Defines a group listing. All methods (and attributes) seen after this
    # directive are placed into a group with the given description as the
    # group name. The group listing is used by templates to organize methods
    # and attributes into respective logical groups. To end a group listing
    # use {tag:!endgroup}.
    #
    # @note A group definition only applies to the scope it is defined in.
    #   If a new class or module is opened after the directive, this directive
    #   will not apply to methods in that class or module.
    # @example
    #   # @!group Callbacks
    #
    #   def before_filter; end
    #   def after_filter; end
    # @see tag:!endgroup
    # @since 0.6.0
    class GroupDirective < Directive
      def call
        return unless handler
        handler.extra_state.group = tag.text
      end
    end

    # Defines a block of text to be expanded whenever the macro is called by name
    # in subsequent docstrings. The macro data can be any arbitrary text data, be
    # it regular documentation, meta-data tags or directives.
    #
    # == Defining a Macro
    #
    # A macro must first be defined in order to be used. Note that a macro is also
    # expanded upon definition if it defined on an object (the docstring of a
    # method, class, module or constant object as opposed to a free standing
    # comment). To define a macro, use the "new" or "attach" identifier in the
    # types specifier list. A macro will also automatically be created if an
    # indented macro data block is given, so the keywords are not strictly needed.
    #
    # === Anonymous Macros
    #
    # In addition to standard named macros, macros can be defined anonymously if
    # no name is given. In this case, they can not be re-used in future docstrings,
    # but they will expand in the first definition. This is useful when needing
    # to take advantage of the macro expansion variables (described below).
    #
    # == Using a Macro
    #
    # To re-use a macro in another docstring after it is defined, simply use
    # <tt>@!macro the_name</tt> with no indented block of macro data. The resulting
    # data will be expanded in place.
    #
    # == Attaching a Macro to a DSL Method
    #
    # Macros can be defined to auto-expand on DSL-style class method calls. To
    # define a macro to be auto expanded in this way, use the "attach" keyword
    # in the type specifier list ("new" is implied).
    #
    # Attached macros can also be attached directly on the class method declaration
    # that provides the DSL method to its subclasses. The syntax in either case
    # is the same.
    #
    # == Macro Expansion Variables
    #
    # In the case of using macros on DSL-style method calls, a number of expansion
    # variables can be used for interpolation inside of the macro data. The variables,
    # similar in syntax to Ruby's global variables, are as follows:
    #
    # * $0 - the method name being called
    # * $1, $2, $3, ... - the Nth argument in the method call
    # * $& - the full source line
    #
    # The following example shows what the expansion variables might hold for a given
    # DSL method call:
    #
    #   property :foo, :a, :b, :c, String
    #   # $0 => "property"
    #   # $1 => "foo"
    #   # $2 => "a"
    #   # $& => "property :foo, :a, :b, :c, String"
    #
    # === Ranges
    #
    # Ranges are also acceptable with the syntax <tt>${N-M}</tt>. Negative values
    # on either N or M are valid, and refer to indexes from the end of the list.
    # Consider a DSL method that creates a method using the first argument with
    # argument names following, ending with the return type of the method. This
    # could be documented as:
    #
    #     # @!macro dsl_method
    #     #   @!method $1(${2--2})
    #     #   @return [${-1}] the return value of $0
    #     create_method_with_args :foo, :a, :b, :c, String
    #
    # As described, the method is using the signature <tt>foo(a, b, c)</tt> and the return
    # type from the last argument, +String+. When using ranges, tokens are joined
    # with commas. Note that this includes using $0:
    #
    #     !!!plain
    #     $0-1 # => Interpolates to "create_method_with_args, foo"
    #
    # If you want to separate them with spaces, use <tt>$1 $2 $3 $4 ...</tt>. Note that
    # if the token cannot be expanded, it will return the empty string (not an error),
    # so it would be safe to list <tt>$1 $2 ... $10</tt>, for example.
    #
    # === Escaping Interpolation
    #
    # Interpolation can be escaped by prefixing the +$+ with +\\\+, like so:
    #
    #     # @!macro foo
    #     #   I have \$2.00 USD.
    #
    # @example Defining a simple macro
    #   # @!macro [new] returnself
    #   #   @return [self] returns itself
    # @example Using a simple macro in multiple docstrings
    #   # Documentation for map
    #   # ...
    #   # @macro returnself
    #   def map; end
    #
    #   # Documentation for filter
    #   # ...
    #   # @macro returnself
    #   def filter; end
    # @example Attaching a macro to a class method (for DSL usage)
    #     class Resource
    #       # Defines a new property
    #       # @param [String] name the property name
    #       # @param [Class] type the property's type
    #       # @!macro [attach] property
    #       #   @return [$2] the $1 property
    #       def self.property(name, type) end
    #     end
    #
    #     class Post < Resource
    #       property :title, String
    #       property :view_count, Integer
    #     end
    # @example Attaching a macro directly to a DSL method
    #     class Post < Resource
    #       # @!macro [attach] property
    #       #   @return [$2] the $1 property
    #       property :title, String
    #
    #       # Macro will expand on this definition too
    #       property :view_count, Integer
    #     end
    # @since 0.7.0
    class MacroDirective < Directive
      def call
        raise TagFormatError if tag.name.nil? && tag.text.to_s.empty?
        unless macro_data = find_or_create
          warn
          return
        end

        self.expanded_text = expand(macro_data)
      end

      private

      def new?
        (tag.types && tag.types.include?('new')) ||
          (tag.text && !tag.text.strip.empty?)
      end

      def attach?
        new? && # must have data or there is nothing to attach
        class_method? || # always attach to class methods
        (tag.types && tag.types.include?('attach'))
      end

      def class_method?
        object && object.is_a?(CodeObjects::MethodObject) &&
          object.scope == :class
      end

      def anonymous?
        tag.name.nil? || tag.name.empty?
      end

      def expand(macro_data)
        return if attach? && class_method?
        return if !anonymous? && new? &&
          (!handler || handler.statement.source.empty?)
        call_params = []
        caller_method = nil
        full_source = ''
        if handler
          call_params = handler.call_params
          caller_method = handler.caller_method
          full_source = handler.statement.source
        end
        all_params = ([caller_method] + call_params).compact
        CodeObjects::MacroObject.expand(macro_data, all_params, full_source)
      end

      def find_or_create
        if new? || attach?
          if handler && attach?
            obj = object ? object :
              P("#{handler.namespace}.#{handler.caller_method}")
          else
            obj = nil
          end
          if anonymous? # anonymous macro
            return tag.text || ""
          else
            macro = CodeObjects::MacroObject.create(tag.name, tag.text, obj)
          end
        else
          macro = CodeObjects::MacroObject.find(tag.name)
        end

        macro ? macro.macro_data : nil
      end

      def warn
        if object && handler
          log.warn "Invalid/missing macro name for " +
            "#{object.path} (#{handler.parser.file}:#{handler.statement.line})"
        end
      end
    end

    # Defines a method object with a given method signature, using indented
    # block data as the method's docstring. The signature is similar to the
    # {tag:overload} tag. The comment containing this directive does not need
    # to be attached to any source, but if it is, that source code will be
    # used as the method's source.
    #
    # To define an attribute method, see {tag:!attribute}
    #
    # @note For backwards compatibility support, you do not need to indent
    #   the method's docstring text. If a +@!method+ directive is seen with
    #   no indented block, the entire docstring is used as the new method's
    #   docstring text.
    # @example Defining a simple method
    #   # @!method quit(username, message = "Quit")
    #   #   Sends a quit message to the server for a +username+.
    #   #   @param [String] username the username to quit
    #   #   @param [String] message the quit message
    #   quit_message_method
    # @example Attaching multiple methods to the same source
    #   # @!method method1
    #   # @!method method2
    #   create_methods :method1, :method2
    # @see tag:!attribute
    # @since 0.7.0
    class MethodDirective < Directive
      SCOPE_MATCH = /\A\s*self\s*\.\s*/

      def call; end

      def after_parse
        return unless handler
        use_indented_text
        create_object
      end

      protected

      def method_name
        sig = sanitized_tag_signature
        if sig && sig =~ /^#{CodeObjects::METHODNAMEMATCH}(\s|\(|$)/
          sig[/\A\s*([^\(; \t]+)/, 1]
        else
          handler.call_params.first
        end
      end

      def method_signature
        "def #{sanitized_tag_signature || method_name}"
      end

      def sanitized_tag_signature
        if tag.name && tag.name =~ SCOPE_MATCH
          parser.state.scope = :class
          $'
        else
          tag.name
        end
      end

      def use_indented_text
        return if tag.text.empty?
        handler = parser.handler
        object = parser.object
        self.parser = parser.class.new(parser.library)
        parser.parse(tag.text, object, handler)
      end

      def create_object
        name = method_name
        scope = parser.state.scope || handler.scope
        visibility = parser.state.visibility || handler.visibility
        ns = CodeObjects::NamespaceObject === object ? object : handler.namespace
        obj = CodeObjects::MethodObject.new(ns, name, scope)
        handler.register_file_info(obj)
        handler.register_source(obj)
        handler.register_visibility(obj, visibility)
        handler.register_group(obj)
        obj.signature = method_signature
        obj.parameters = OverloadTag.new(:overload, method_signature).parameters
        obj.docstring = Docstring.new!(parser.text, parser.tags, obj,
          parser.raw_text, parser.reference)
        handler.register_module_function(obj)
        obj
      end
    end

    # Defines an attribute with a given name, using indented block data as the
    # attribute's docstring. If the type specifier is supplied with "r", "w", or
    # "rw", the attribute is made readonly, writeonly or readwrite respectively.
    # A readwrite attribute is the default, if no type is specified. The comment
    # containing this directive does not need to be attached to any source, but
    # if it is, that source code will be used as the method's source.
    #
    # To define an regular method, see {tag:!method}
    #
    # @note For backwards compatibility support, you do not need to indent
    #   the attribute's docstring text. If an +@!attribute+ directive is seen with
    #   no indented block, the entire docstring is used as the new attribute's
    #   docstring text.
    # @example Defining a simple readonly attribute
    #   # @!attribute [r] count
    #   #   @return [Fixnum] the size of the list
    # @example Defining a simple readwrite attribute
    #   # @!attribute name
    #   #   @return [String] the name of the user
    # @see tag:!method
    # @since 0.7.0
    class AttributeDirective < MethodDirective
      def after_parse
        return unless handler
        use_indented_text
        create_attribute_data(create_object)
      end

      protected

      def method_name
        name = sanitized_tag_signature || handler.call_params.first
        name += '=' unless readable?
        name
      end

      def method_signature
        if readable?
          "def #{method_name}"
        else
          "def #{method_name}(value)"
        end
      end

      private

      def create_attribute_data(object)
        return unless object
        clean_name = object.name.to_s.sub(/=$/, '')
        attrs = object.namespace.attributes[object.scope]
        attrs[clean_name] ||= SymbolHash[:read => nil, :write => nil]
        if readable?
          attrs[clean_name][:read] = object
        end
        if writable?
          if object.name.to_s[-1,1] == '='
            writer = object
            writer.parameters = [['value', nil]]
          else
            writer = CodeObjects::MethodObject.new(object.namespace,
              object.name.to_s + '=', object.scope)
            writer.signature = "def #{object.name}=(value)"
            writer.visibility = object.visibility
            writer.dynamic = object.dynamic
            writer.source = object.source
            writer.group = object.group
            writer.parameters = [['value', nil]]
            handler.register_file_info(writer)
          end
          attrs[clean_name][:write] = writer
        end
      end

      def writable?
        !tag.types || tag.types.join.include?('w')
      end

      def readable?
        !tag.types || tag.types.join =~ /(?!w)r/
      end
    end

    # Parses a block of code as if it were present in the source file at that
    # location. This directive is useful if a class has dynamic meta-programmed
    # behaviour that cannot be recognized by YARD.
    #
    # You can specify the language of the code block using the types
    # specification list. By default, the code language is "ruby".
    #
    # @example Documenting dynamic module inclusion
    #   class User
    #     # includes "UserMixin" and extends "UserMixin::ClassMethods"
    #     # using the UserMixin.included callback.
    #     # @!parse include UserMixin
    #     # @!parse extend UserMixin::ClassMethods
    #   end
    # @example Declaring a method as an attribute
    #   # This should really be an attribute
    #   # @!parse attr_reader :foo
    #   def object; @parent.object end
    # @example Parsing C code
    #   # @!parse [c]
    #   #   void Init_Foo() {
    #   #     rb_define_method(rb_cFoo, "method", method, 0);
    #   #   }
    # @since 0.8.0
    class ParseDirective < Directive
      def call
        lang = tag.types ? tag.types.first.to_sym :
          (handler ? handler.parser.parser_type : :ruby)
        if handler && lang == handler.parser.parser_type
          pclass = Parser::SourceParser.parser_types[handler.parser.parser_type]
          pobj = pclass.new(tag.text, handler.parser.file)
          pobj.parse
          handler.parser.process(pobj.enumerator)
        else # initialize a new parse chain
          src_parser = Parser::SourceParser.new(lang, handler ? handler.globals : nil)
          src_parser.file = handler.parser.file if handler
          src_parser.parse(StringIO.new(tag.text))
        end
      end
    end

    # Modifies the current parsing scope (class or instance). If this
    # directive is defined on a docstring attached to an object definition,
    # it is applied only to that object. Otherwise, it applies the scope
    # to all future objects in the namespace.
    #
    # @example Modifying the scope of a DSL method
    #   # @!scope class
    #   cattr_accessor :subclasses
    # @example Modifying the scope of a set of methods
    #   # @!scope class
    #
    #   # Documentation for method1
    #   def method1; end
    #
    #   # Documentation for method2
    #   def method2; end
    # @since 0.7.0
    class ScopeDirective < Directive
      def call
        if %w(class instance module).include?(tag.text)
          if object.is_a?(CodeObjects::MethodObject)
            object.scope = tag.text.to_sym
          else
            parser.state.scope = tag.text.to_sym
          end
        end
      end
    end

    # Modifies the current parsing visibility (public, protected, or private).
    # If this directive is defined on a docstring attached to an object
    # definition, it is applied only to that object. Otherwise, it applies
    # the visibility to all future objects in the namespace.
    #
    # @example Modifying the visibility of a DSL method
    #   # @!visibility private
    #   cattr_accessor :subclasses
    # @example Modifying the visibility of a set of methods
    #   # Note that Ruby's "protected" is recommended over this directive
    #   # @!visibility protected
    #
    #   # Documentation for method1
    #   def method1; end
    #
    #   # Documentation for method2
    #   def method2; end
    # @since 0.7.0
    class VisibilityDirective < Directive
      def call
        if %w(public protected private).include?(tag.text)
          if object.is_a?(CodeObjects::Base)
            object.visibility = tag.text.to_sym
          else
            parser.state.visibility = tag.text.to_sym
          end
        end
      end
    end
  end
end