# Module for vrobot4 bot modules.
module Vrobot4::Module
   # A command function. Holds extra info such as help and permissions.
   class Command
      attr_reader :help_str # @return [String] help string for this command

      # @param fn [Method] method to be called on run
      # @param help [String] help string for this command
      # @param roles [String] list of roles that can use this command
      def initialize fn, help, roles
         @function = fn
         @help_str = help
         @roles    = /[#{roles}]/
      end

      # Checks if this command is usable in a given context.
      # @param m [Vrobot4::Server::Message] message for context
      # @return [Boolean] true if command is usable, false otherwise
      def usable_in? m
         m.user.roles.scan(@roles).any? and @function.owner.usable_in? m
      end

      # Calls the method attached to this command.
      # @param m [Vrobot4::Server::Message] message for context
      # @param argv [String] argument string
      # @return [void]
      def run m, argv
         @function.call(m, argv)
      end
   end

   # A bot module. Holds commands and callbacks.
   class Module
      # Checks if this module is usable in a given context.
      # @param m [Vrobot4::Server::Message] message for context
      # @return [Boolean] true if usable, false otherwise
      def self.usable_in? m
         role = m.user.roles
         mprm = m.serv.mprm
         retm, retc, retr = true, false, false
         retm = mprm[:glob][self]                  if mprm[:glob].key? self
         retc = mprm[:chan][self][m.chan]          if mprm[:chan].key? self
         retr = mprm[:role][self].scan /[#{role}]/ if mprm[:role].key? self
         retm or retc or retr
      end

      # @param info [Hash] arbitrary extra information for this module
      def initialize info
         @commands = {}
         @info = info
         Vrobot4.log :DEBUG, "initialized #{self.to_s}"
      end

      # Callback for message receiving.
      # @param m [Vrobot4::Server::Message] message received
      # @return [Boolean] if this should block further message callbacks
      def on_message m
         false
      end

      # Callback for command receiving.
      # @param m [Vrobot4::Server::Message] message that triggered this call
      # @param cnam [String] name of command to call
      # @param argv [String] array of string arguments
      # @return [Boolean] if this should block further command callbacks
      def on_command m, cnam, argv
         if (cmd = cmds(m)[cnam])
            begin
               cmd.run(m, argv)
            rescue
               m.reply "Error:", $!.to_s
            end
            true
         else
            false
         end
      end

      # Gets all commands usable in a specified context.
      # @param m [Vrobot4::Server::Message] message for context
      # @return [Hash<String, Vrobot4::Module::Command>]
      #  a hash of all commands by name
      def cmds m
         @commands.select do |name, cmd|
            cmd.usable_in? m
         end
      end

      protected

      # Registers a command into this module.
      # @param fn [Symbol] name of method to add
      # @param names [String, Array] name(s) to add this command by
      # @param help [String] help string to use for this command
      # @param roles [String] roles to allow this command to use
      # @return [Vrobot4::Module::Command] command added
      def register fn, names, help = nil, roles: ?v
         help = "No help available for this command." if help == nil
         cmd = Command.new(self.method(fn), help, roles).freeze
         if names.is_a? String
            @commands[names] = cmd
         else
            names.each {|name| @commands[name] = cmd}
         end
         cmd
      end

      # Check argument validity and count.
      #
      # Specifiers include:
      # [N] A number.
      # [S] An arbitrary string.
      # [*] Any amount of arbitrary arguments. Must be the last optional arg.
      #
      # @param argv [String, Array] array of arguments or a string
      # @param req [String] specifier string of required arguments
      # @param opt [String] specifier string of optional arguments
      # @return [String, Array] argv
      def check_args argv, req, opt = ""
         if argv.is_a? Array then
            if argv.length < req.length
               raise ArgumentError, "Not enough arguments"
            elsif opt[-1] != '*' and argv.length > req.length + opt.length
               raise ArgumentError, "Too many arguments"
            end

            for i in (0 ... req.length)
               check_arg argv[i], i, req[i]
            end

            for i in (0 ... argv.length - req.length)
               break if opt[i] == '*'
               argn = i + req.length
               check_arg argv[argn], argn, opt[i]
            end
         else
            check_arg argv, 0, req[0]
         end
         argv
      end

      private

      # Helper function for {#check_args}.
      # @param arg [String] the argument to check
      # @param i [Integer] which argument this is
      # @param req [String] type that the argument should be
      # @return [void]
      def check_arg arg, i, req
         case req
         when ?N
            unless Vrobot4.is_num? arg.strip
               raise ArgumentError, "Expected a number for arg #{i}"
            end
         when ?S # Don't need to check anything here.
         else
            raise ArgumentError, "Invalid argument specifier #{req}"
         end
      end
   end

   # Adds a module type to the global list.
   # @param type [Class] module type to add
   # @param server [String] server type this module is restricted to (or none)
   # @param servflags [String] flags the server must have to use this (or none)
   # @return [void]
   def self.add_module_type type, server: nil, servflags: nil
      @@module_types[type.type] = {
         type:      type,
         server:    server,
         servflags: servflags ? /[#{servflags}]/ : nil
      }
      Vrobot4.log :INFO, "added module type #{type.type}"
   end

   # Gets a module type by name from the global list.
   # @param name [String] name of the module type to find
   # @return [Hash] a hash containing info about the type
   def self.get_module_type name
      @@module_types[name]
   end

   # The set of all module types.
   @@module_types = {}
end

## EOF