require "strscan"

module Bundler
  class LockfileParser
    attr_reader :sources, :dependencies, :specs, :platforms

    def initialize(lockfile)
      @platforms    = []
      @sources      = []
      @dependencies = []
      @specs        = []
      @state        = :source

      lockfile.split(/\n+/).each do |line|
        if line == "DEPENDENCIES"
          @state = :dependency
        elsif line == "PLATFORMS"
          @state = :platform
        else
          send("parse_#{@state}", line)
        end
      end
    end

  private

    TYPES = {
      "GIT"  => Bundler::Source::Git,
      "GEM"  => Bundler::Source::Rubygems,
      "PATH" => Bundler::Source::Path
    }

    def parse_source(line)
      case line
      when "GIT", "GEM", "PATH"
        @current_source = nil
        @opts, @type = {}, line
      when "  specs:"
        @current_source = TYPES[@type].from_lock(@opts)
        @sources << @current_source
      when /^  ([a-z]+): (.*)$/i
        if @opts[$1]
          @opts[$1] = Array(@opts[$1])
          @opts[$1] << $2
        else
          @opts[$1] = $2
        end
      else
        parse_spec(line)
      end
    end

    NAME_VERSION = '(?! )(.*?)(?: \((.*)\))?'

    def parse_dependency(line)
      if line =~ %r{^ {2}#{NAME_VERSION}(!)?$}
        name, version, pinned = $1, $2, $3

        dep = Bundler::Dependency.new(name, version)

        if pinned
          dep.source = @specs.find { |s| s.name == dep.name }.source

          # Path sources need to know what the default name / version
          # to use in the case that there are no gemspecs present. A fake
          # gemspec is created based on the version set on the dependency
          # TODO: Use the version from the spec instead of from the dependency
          if version =~ /^= (.+)$/ && dep.source.is_a?(Bundler::Source::Path)
            dep.source.name    = name
            dep.source.version = $1
          end
        end

        @dependencies << dep
      end
    end

    def parse_spec(line)
      if line =~ %r{^ {4}#{NAME_VERSION}$}
        @current_spec = LazySpecification.new($1, $2)
        @current_spec.source = @current_source
        @specs << @current_spec
      elsif line =~ %r{^ {6}#{NAME_VERSION}$}
        @current_spec.dependencies << Gem::Dependency.new($1, $2)
      end
    end

    def parse_platform(line)
      if line =~ /^  (.*)$/
        @platforms << Gem::Platform.new($1)
      end
    end
  end
end