require ‘pathname’ require ‘forwardable’ require ‘tsort’ require ‘shellwords’

module MRuby

module Gem
  class << self
    attr_accessor :current
  end
  LinkerConfig = Struct.new(:libraries, :library_paths, :flags, :flags_before_libraries, :flags_after_libraries)

  class Specification
    include Rake::DSL
    extend Forwardable
    def_delegators :@build, :filename, :objfile, :libfile, :exefile

    attr_accessor :name, :dir, :build
    alias mruby build
    attr_accessor :build_config_initializer
    attr_accessor :mrblib_dir, :objs_dir

    attr_accessor :version
    attr_accessor :description, :summary
    attr_accessor :homepage
    attr_accessor :licenses, :authors
    alias :license= :licenses=
    alias :author= :authors=

    attr_accessor :rbfiles, :objs
    attr_accessor :test_objs, :test_rbfiles, :test_args
    attr_accessor :test_preload

    attr_accessor :bins

    attr_accessor :requirements
    attr_reader :dependencies, :conflicts

    attr_accessor :export_include_paths

    attr_reader :generate_functions

    attr_block MRuby::Build::COMMANDS

    def initialize(name, &block)
      @name = name
      @initializer = block
      @version = "0.0.0"
      @mrblib_dir = "mrblib"
      @objs_dir = "src"
      MRuby::Gem.current = self
    end

    def setup
      MRuby::Gem.current = self
      MRuby::Build::COMMANDS.each do |command|
        instance_variable_set("@#{command}", @build.send(command).clone)
      end
      @linker = LinkerConfig.new([], [], [], [], [])

      @rbfiles = Dir.glob("#{@dir}/#{@mrblib_dir}     .rb").sort
      @objs = Dir.glob("#{@dir}/#{@objs_dir}/*.{c,cpp,cxx,cc,m,asm,s,S}").map do |f|
        objfile(f.relative_path_from(@dir).to_s.pathmap("#{build_dir}/%X"))
      end

      @generate_functions = !(@rbfiles.empty? && @objs.empty?)
      @objs << objfile("#{build_dir}/gem_init") if @generate_functions

      @test_rbfiles = Dir.glob("#{dir}/test/   *.rb")
      @test_objs = Dir.glob("#{dir}/test/*.{c,cpp,cxx,cc,m,asm,s,S}").map do |f|
        objfile(f.relative_path_from(dir).to_s.pathmap("#{build_dir}/%X"))
      end
      @custom_test_init = !@test_objs.empty?
      @test_preload = nil # 'test/assert.rb'
      @test_args = {}

      @bins = []

      @requirements = []
      @dependencies, @conflicts = [], []
      @export_include_paths = []
      @export_include_paths << "#{dir}/include" if File.directory? "#{dir}/include"

      instance_eval(&@initializer)

      if !name || !licenses || !authors
        fail "#{name || dir} required to set name, license(s) and author(s)"
      end

      build.libmruby << @objs

      instance_eval(&@build_config_initializer) if @build_config_initializer
    end

    def setup_compilers
      compilers.each do |compiler|
        compiler.define_rules build_dir, "#{dir}"
        compiler.defines << %Q[MRBGEM_#{funcname.upcase}_VERSION=#{version}]
        compiler.include_paths << "#{dir}/include" if File.directory? "#{dir}/include"
      end

      define_gem_init_builder if @generate_functions
    end

    def add_dependency(name, *requirements)
      default_gem = requirements.last.kind_of?(Hash) ? requirements.pop : nil
      requirements = ['>= 0.0.0'] if requirements.empty?
      requirements.flatten!
      @dependencies << {:gem => name, :requirements => requirements, :default => default_gem}
    end

    def add_test_dependency(*args)
      add_dependency(*args) if build.test_enabled?
    end

    def add_conflict(name, *req)
      @conflicts << {:gem => name, :requirements => req.empty? ? nil : req}
    end

    def self.bin=(bin)
      @bins = [bin].flatten
    end

    def build_dir
      "#{build.build_dir}/mrbgems/#{name}"
    end

    def test_rbireps
      "#{build_dir}/gem_test.c"
    end

    def search_package(name, version_query=nil)
      package_query = name
      package_query += " #{version_query}" if version_query
      _pp "PKG-CONFIG", package_query
      escaped_package_query = Shellwords.escape(package_query)
      if system("pkg-config --exists #{escaped_package_query}")
        cc.flags += [%x`pkg-config --cflags #{escaped_package_query}`.strip]
        cxx.flags += [%x`pkg-config --cflags #{escaped_package_query}`.strip]
        linker.flags_before_libraries += [%x`pkg-config --libs #{escaped_package_query}`.strip]
        true
      else
        false
      end
    end

    def funcname
      @funcname ||= @name.gsub('-', '_')
    end

    def compilers
      MRuby::Build::COMPILERS.map do |c|
        instance_variable_get("@#{c}")
      end
    end

    def define_gem_init_builder
      file objfile("#{build_dir}/gem_init") => [ "#{build_dir}/gem_init.c", File.join(dir, "mrbgem.rake") ]
      file "#{build_dir}/gem_init.c" => [build.mrbcfile, __FILE__] + [rbfiles].flatten do |t|
        FileUtils.mkdir_p build_dir
        generate_gem_init("#{build_dir}/gem_init.c")
      end
    end

    def generate_gem_init(fname)
      open(fname, 'w') do |f|
        print_gem_init_header f
        build.mrbc.run f, rbfiles, "gem_mrblib_irep_#{funcname}" unless rbfiles.empty?
        f.puts %Q[void mrb_#{funcname}_gem_init(mrb_state *mrb);]
        f.puts %Q[void mrb_#{funcname}_gem_final(mrb_state *mrb);]
        f.puts %Q[]
        f.puts %Q[void GENERATED_TMP_mrb_#{funcname}_gem_init(mrb_state *mrb) {]
        f.puts %Q[  int ai = mrb_gc_arena_save(mrb);]
        f.puts %Q[  mrb_#{funcname}_gem_init(mrb);] if objs != [objfile("#{build_dir}/gem_init")]
        unless rbfiles.empty?
          f.puts %Q[  mrb_load_irep(mrb, gem_mrblib_irep_#{funcname});]
          f.puts %Q[  if (mrb->exc) {]
          f.puts %Q[    mrb_print_error(mrb);]
          f.puts %Q[    exit(EXIT_FAILURE);]
          f.puts %Q[  }]
        end
        f.puts %Q[  mrb_gc_arena_restore(mrb, ai);]
        f.puts %Q[}]
        f.puts %Q[]
        f.puts %Q[void GENERATED_TMP_mrb_#{funcname}_gem_final(mrb_state *mrb) {]
        f.puts %Q[  mrb_#{funcname}_gem_final(mrb);] if objs != [objfile("#{build_dir}/gem_init")]
        f.puts %Q[}]
      end
    end # generate_gem_init

    def print_gem_comment(f)
      f.puts %Q[/*]
      f.puts %Q[ * This file is loading the irep]
      f.puts %Q[ * Ruby GEM code.]
      f.puts %Q[ *]
      f.puts %Q[ * IMPORTANT:]
      f.puts %Q[ *   This file was generated!]
      f.puts %Q[ *   All manual changes will get lost.]
      f.puts %Q[   ]
    end

    def print_gem_init_header(f)
      print_gem_comment(f)
      f.puts %Q[#include <stdlib.h>] unless rbfiles.empty?
      f.puts %Q[#include <mruby.h>]
      f.puts %Q[#include <mruby/irep.h>] unless rbfiles.empty?
    end

    def print_gem_test_header(f)
      print_gem_comment(f)
      f.puts %Q[#include <stdio.h>]
      f.puts %Q[#include <stdlib.h>]
      f.puts %Q[#include <mruby.h>]
      f.puts %Q[#include <mruby/irep.h>]
      f.puts %Q[#include <mruby/variable.h>]
      f.puts %Q[#include <mruby/hash.h>] unless test_args.empty?
    end

    def test_dependencies
      [@name]
    end

    def custom_test_init?
      @custom_test_init
    end

    def version_ok?(req_versions)
      req_versions.map do |req|
        cmp, ver = req.split
        cmp_result = Version.new(version) <=> Version.new(ver)
        case cmp
        when '=' then cmp_result == 0
        when '!=' then cmp_result != 0
        when '>' then cmp_result == 1
        when '<' then cmp_result == -1
        when '>=' then cmp_result >= 0
        when '<=' then cmp_result <= 0
        when '~>'
          Version.new(version).twiddle_wakka_ok?(Version.new(ver))
        else
          fail "Comparison not possible with '#{cmp}'"
        end
      end.all?
    end
  end # Specification

  class Version
    include Comparable
    include Enumerable

    def <=>(other)
      ret = 0
      own = to_enum

      other.each do |oth|
        begin
          ret = own.next <=> oth
        rescue StopIteration
          ret = 0 <=> oth
        end

        break unless ret == 0
      end

      ret
    end

    # ~> compare algorithm
    #
    # Example:
    #    ~> 2.2   means >= 2.2.0 and < 3.0.0
    #    ~> 2.2.0 means >= 2.2.0 and < 2.3.0
    def twiddle_wakka_ok?(other)
      gr_or_eql = (self <=> other) >= 0
      still_minor = (self <=> other.skip_minor) < 0
      gr_or_eql and still_minor
    end

    def skip_minor
      a = @ary.dup
      a.slice!(-1)
      a[-1] = a[-1].succ
      a
    end

    def initialize(str)
      @str = str
      @ary = @str.split('.').map(&:to_i)
    end

    def each(&block); @ary.each(&block); end
    def [](index); @ary[index]; end
    def []=(index, value)
      @ary[index] = value
      @str = @ary.join('.')
    end
    def slice!(index)
      @ary.slice!(index)
      @str = @ary.join('.')
    end
  end # Version

  class List
    include Enumerable

    def initialize
      @ary = []
    end

    def each(&b)
      @ary.each(&b)
    end

    def <<(gem)
      unless @ary.detect {|g| g.dir == gem.dir }
        @ary << gem
      else
        # GEM was already added to this list
      end
    end

    def empty?
      @ary.empty?
    end

    def generate_gem_table build
      gem_table = @ary.reduce({}) { |res,v| res[v.name] = v; res }

      default_gems = []
      each do |g|
        g.dependencies.each do |dep|
          unless gem_table.key? dep[:gem]
            if dep[:default]; default_gems << dep
            elsif File.exist? "#{MRUBY_ROOT}/mrbgems/#{dep[:gem]}" # check core
              default_gems << { :gem => dep[:gem], :default => { :core => dep[:gem] } }
            else # fallback to mgem-list
              default_gems << { :gem => dep[:gem], :default => { :mgem => dep[:gem] } }
            end
          end
        end
      end

      until default_gems.empty?
        def_gem = default_gems.pop

        spec = build.gem def_gem[:default]
        fail "Invalid gem name: #{spec.name} (Expected: #{def_gem[:gem]})" if spec.name != def_gem[:gem]
        spec.setup

        spec.dependencies.each do |dep|
          unless gem_table.key? dep[:gem]
            if dep[:default]; default_gems << dep
            else default_gems << { :gem => dep[:gem], :default => { :mgem => dep[:gem] } }
            end
          end
        end
        gem_table[spec.name] = spec
      end

      each do |g|
        g.dependencies.each do |dep|
          name = dep[:gem]
          req_versions = dep[:requirements]
          dep_g = gem_table[name]

          # check each GEM dependency against all available GEMs
          if dep_g.nil?
            fail "The GEM '#{g.name}' depends on the GEM '#{name}' but it could not be found"
          end
          unless dep_g.version_ok? req_versions
            fail "#{name} version should be #{req_versions.join(' and ')} but was '#{dep_g.version}'"
          end
        end

        cfls = g.conflicts.select { |c|
          cfl_g = gem_table[c[:gem]]
          cfl_g and cfl_g.version_ok?(c[:requirements] || ['>= 0.0.0'])
        }.map { |c| "#{c[:gem]}(#{gem_table[c[:gem]].version})" }
        fail "Conflicts of gem `#{g.name}` found: #{cfls.join ', '}" unless cfls.empty?
      end

      gem_table
    end

    def tsort_dependencies ary, table, all_dependency_listed = false
      unless all_dependency_listed
        left = ary.dup
        until left.empty?
          v = left.pop
          table[v].dependencies.each do |dep|
            left.push dep[:gem]
            ary.push dep[:gem]
          end
        end
      end

      ary.uniq!
      table.instance_variable_set :@root_gems, ary
      class << table
        include TSort
        def tsort_each_node &b
          @root_gems.each &b
        end

        def tsort_each_child(n, &b)
          fetch(n).dependencies.each do |v|
            b.call v[:gem]
          end
        end
      end

      begin
        table.tsort.map { |v| table[v] }
      rescue TSort::Cyclic => e
        fail "Circular mrbgem dependency found: #{e.message}"
      end
    end

    def check(build)
      gem_table = generate_gem_table build

      @ary = tsort_dependencies gem_table.keys, gem_table, true

      each(&:setup_compilers)

      each do |g|
        import_include_paths(g)
      end
    end

    def import_include_paths(g)
      gem_table = @ary.reduce({}) { |res,v| res[v.name] = v; res }
      g.dependencies.each do |dep|
        dep_g = gem_table[dep[:gem]]
        # We can do recursive call safely
        # as circular dependency has already detected in the caller.
        import_include_paths(dep_g)

        dep_g.export_include_paths.uniq!
        g.compilers.each do |compiler|
          compiler.include_paths += dep_g.export_include_paths
          g.export_include_paths += dep_g.export_include_paths
          compiler.include_paths.uniq!
          g.export_include_paths.uniq!
        end
      end
    end
  end # List
end # Gem

GemBox = Object.new
class << GemBox
  attr_accessor :path

  def new(&block); block.call(self); end
  def config=(obj); @config = obj; end
  def gem(gemdir, &block); @config.gem(gemdir, &block); end
end # GemBox

end # MRuby