require 'pathname'
require 'fileutils'
require 'tempfile'
require 'middleman-core/rack'
require 'middleman-core/callback_manager'
require 'middleman-core/contracts'

module Middleman
  class Builder
    extend Forwardable
    include Contracts

    # Make app & events available to `after_build` callbacks.
    attr_reader :app, :events

    # Reference to the Thor class.
    attr_accessor :thor

    # Logger comes from App.
    def_delegator :@app, :logger

    # Sort order, images, fonts, js/css and finally everything else.
    SORT_ORDER = %w(.png .jpeg .jpg .gif .bmp .svg .svgz .webp .ico .woff .woff2 .otf .ttf .eot .js .css)

    # Create a new Builder instance.
    # @param [Middleman::Application] app The app to build.
    # @param [Hash] opts The builder options
    def initialize(app, opts={})
      @app = app
      @source_dir = Pathname(File.join(@app.root, @app.config[:source]))
      @build_dir = Pathname(@app.config[:build_dir])

      if @build_dir.expand_path.relative_path_from(@source_dir).to_s =~ /\A[.\/]+\Z/
        raise ":build_dir (#{@build_dir}) cannot be a parent of :source_dir (#{@source_dir})"
      end

      @glob = opts.fetch(:glob)
      @cleaning = opts.fetch(:clean)

      rack_app = ::Middleman::Rack.new(@app).to_app
      @rack = ::Rack::MockRequest.new(rack_app)

      @callbacks = ::Middleman::CallbackManager.new
      @callbacks.install_methods!(self, [:on_build_event])
    end

    # Run the build phase.
    # @return [Boolean] Whether the build was successful.
    Contract Bool
    def run!
      @has_error = false
      @events = {}

      @app.execute_callbacks(:before_build, [self])

      queue_current_paths if @cleaning
      prerender_css

      output_files

      clean if @cleaning

      ::Middleman::Profiling.report('build')

      @app.execute_callbacks(:after_build, [self])

      !@has_error
    end

    # Pre-request CSS to give Compass a chance to build sprites
    # @return [Array<Resource>] List of css resources that were output.
    Contract ResourceList
    def prerender_css
      logger.debug '== Prerendering CSS'

      css_files = @app.sitemap.resources.select do |resource|
        resource.ext == '.css'
      end.each(&method(:output_resource))

      logger.debug '== Checking for Compass sprites'

      # Double-check for compass sprites
      @app.files.find_new_files!
      @app.sitemap.ensure_resource_list_updated!

      css_files
    end

    # Find all the files we need to output and do so.
    # @return [Array<Resource>] List of resources that were output.
    Contract ResourceList
    def output_files
      logger.debug '== Building files'

      # Sort paths to be built by the above order. This is primarily so Compass can
      # find files in the build folder when it needs to generate sprites for the
      # css files.
      #
      # Loop over all the paths and build them.
      @app.sitemap.resources
        .sort_by { |resource| SORT_ORDER.index(resource.ext) || 100 }
        .reject { |resource| resource.ext == '.css' }
        .select { |resource| !@glob || File.fnmatch(@glob, resource.destination_path) }
        .each(&method(:output_resource))
    end

    # Figure out the correct event mode.
    # @param [Pathname] output_file The output file path.
    # @param [String] source The source file path.
    # @return [Symbol]
    Contract Pathname, String => Symbol
    def which_mode(output_file, source)
      if !output_file.exist?
        :created
      else
        FileUtils.compare_file(source.to_s, output_file.to_s) ? :identical : :updated
      end
    end

    # Create a tempfile for a given output with contents.
    # @param [Pathname] output_file The output path.
    # @param [String] contents The file contents.
    # @return [Tempfile]
    Contract Pathname, String => Tempfile
    def write_tempfile(output_file, contents)
      file = Tempfile.new([
        File.basename(output_file),
        File.extname(output_file)
      ])
      file.binmode
      file.write(contents)
      file.close
      file
    end

    # Actually export the file.
    # @param [Pathname] output_file The path to output to.
    # @param [String|Pathname] source The source path or contents.
    # @return [void]
    Contract Pathname, Or[String, Pathname] => Any
    def export_file!(output_file, source)
      source = write_tempfile(output_file, source.to_s) if source.is_a? String

      method, source_path = if source.is_a? Tempfile
        [FileUtils.method(:mv), source.path]
      else
        [FileUtils.method(:cp), source.to_s]
      end

      mode = which_mode(output_file, source_path)

      if mode == :created || mode == :updated
        FileUtils.mkdir_p(output_file.dirname)
        method.call(source_path, output_file.to_s)
      end

      source.unlink if source.is_a? Tempfile

      trigger(mode, output_file)
    end

    # Try to output a resource and capture errors.
    # @param [Middleman::Sitemap::Resource] resource The resource.
    # @return [void]
    Contract IsA['Middleman::Sitemap::Resource'] => Any
    def output_resource(resource)
      output_file = @build_dir + resource.destination_path.gsub('%20', ' ')

      begin
        if resource.binary?
          export_file!(output_file, resource.source_file[:full_path])
        else
          response = @rack.get(URI.escape(resource.request_path))

          # If we get a response, save it to a tempfile.
          if response.status == 200
            export_file!(output_file, binary_encode(response.body))
          else
            @has_error = true
            trigger(:error, output_file, response.body)
          end
        end
      rescue => e
        @has_error = true
        trigger(:error, output_file, "#{e}\n#{e.backtrace.join("\n")}")
      end

      return unless @cleaning
      return unless output_file.exist?

      # handle UTF-8-MAC filename on MacOS
      cleaned_name = if RUBY_PLATFORM =~ /darwin/
        output_file.to_s.encode('UTF-8', 'UTF-8-MAC')
      else
        output_file
      end

      @to_clean.delete(Pathname(cleaned_name))
    end

    # Get a list of all the paths in the destination folder and save them
    # for comparison against the files we build in this cycle
    # @return [void]
    Contract Any
    def queue_current_paths
      @to_clean = []

      return unless File.exist?(@app.config[:build_dir])

      paths = ::Middleman::Util.all_files_under(@app.config[:build_dir]).map do |path|
        Pathname(path)
      end

      @to_clean = paths.select do |path|
        path.to_s !~ /\/\./ || path.to_s =~ /\.(htaccess|htpasswd)/
      end

      # handle UTF-8-MAC filename on MacOS
      @to_clean = @to_clean.map do |path|
        if RUBY_PLATFORM =~ /darwin/
          Pathname(path.to_s.encode('UTF-8', 'UTF-8-MAC'))
        else
          Pathname(path)
        end
      end
    end

    # Remove files which were not built in this cycle
    Contract ArrayOf[Pathname]
    def clean
      @to_clean.each do |f|
        FileUtils.rm(f)
        trigger(:deleted, f)
      end
    end

    Contract String => String
    def binary_encode(string)
      string.force_encoding('ascii-8bit') if string.respond_to?(:force_encoding)
      string
    end

    Contract Symbol, Or[String, Pathname], Maybe[String] => Any
    def trigger(event_type, target, extra=nil)
      @events[event_type] ||= []
      @events[event_type] << target

      execute_callbacks(:on_build_event, [event_type, target, extra])
    end
  end
end