# frozen_string_literal: true

require_dependency 'stylesheet/common'
require_dependency 'global_path'

module Stylesheet
  class Importer < SassC::Importer
    include GlobalPath

    THEME_TARGETS ||= %w{embedded_theme mobile_theme desktop_theme}

    def self.special_imports
      @special_imports ||= {}
    end

    def self.register_import(name, &blk)
      special_imports[name] = blk
    end

    # Contained in function so that it can be called repeatedly from test mode
    def self.register_imports!
      @special_imports = {}

      register_import "theme_field" do
        Import.new("#{theme_dir(@theme_id)}/theme_field.scss", source: @theme_field)
      end

      Discourse.plugins.each do |plugin|
        plugin_directory_name = plugin.directory_name

        ["", "mobile", "desktop"].each do |type|
          asset_name = type.present? ? "#{plugin_directory_name}_#{type}" : plugin_directory_name
          stylesheets = type.present? ? DiscoursePluginRegistry.send("#{type}_stylesheets") : DiscoursePluginRegistry.stylesheets

          if stylesheets[plugin_directory_name].present?
            register_import asset_name do
              import_files(stylesheets[plugin_directory_name])
            end
          end
        end
      end

      register_import "font" do
        body_font = DiscourseFonts.fonts.find { |f| f[:key] == SiteSetting.base_font }
        heading_font = DiscourseFonts.fonts.find { |f| f[:key] == SiteSetting.heading_font }
        contents = +""

        if body_font.present?
          contents << <<~EOF
            #{font_css(body_font)}

            :root {
              --font-family: #{body_font[:stack]};
            }
          EOF
        end

        if heading_font.present?
          contents << <<~EOF
            #{font_css(heading_font)}

            :root {
              --heading-font-family: #{heading_font[:stack]};
            }
          EOF
        end

        Import.new("font.scss", source: contents)
      end

      register_import "wizard_fonts" do
        contents = +""

        DiscourseFonts.fonts.each do |font|
          if font[:key] == "system"
            # Overwrite font definition because the preview canvases in the wizard require explicit @font-face definitions.
            # uses same technique as https://github.com/jonathantneal/system-font-css
            font[:variants] = [
              { src: 'local(".SFNS-Regular"), local(".SFNSText-Regular"), local(".HelveticaNeueDeskInterface-Regular"), local(".LucidaGrandeUI"), local("Segoe UI"), local("Ubuntu"), local("Roboto-Regular"), local("DroidSans"), local("Tahoma")', weight: 400 },
              { src: 'local(".SFNS-Bold"), local(".SFNSText-Bold"), local(".HelveticaNeueDeskInterface-Bold"), local(".LucidaGrandeUI"), local("Segoe UI Bold"), local("Ubuntu Bold"), local("Roboto-Bold"), local("DroidSans-Bold"), local("Tahoma Bold")', weight: 700 }
            ]
          end

          contents << font_css(font)
          contents << <<~EOF
            .body-font-#{font[:key].tr("_", "-")} {
              font-family: #{font[:stack]};
            }
            .heading-font-#{font[:key].tr("_", "-")} h2 {
              font-family: #{font[:stack]};
            }
          EOF
        end

        Import.new("wizard_fonts.scss", source: contents)
      end

      register_import "plugins_variables" do
        import_files(DiscoursePluginRegistry.sass_variables)
      end

      register_import "theme_colors" do
        contents = +""
        if @color_scheme_id
          colors = begin
            ColorScheme.find(@color_scheme_id).resolved_colors
          rescue
            ColorScheme.base_colors
          end
        else
          colors = (@theme_id && theme.color_scheme) ? theme.color_scheme.resolved_colors : ColorScheme.base_colors
        end

        colors.each do |n, hex|
          contents << "$#{n}: ##{hex} !default;\n"
        end

        Import.new("theme_colors.scss", source: contents)
      end

      register_import "theme_variables" do
        contents = +""

        theme&.all_theme_variables&.each do |field|
          if field.type_id == ThemeField.types[:theme_upload_var]
            if upload = field.upload
              url = upload_cdn_path(upload.url)
              contents << "$#{field.name}: unquote(\"#{url}\");\n"
            end
          else
            contents << to_scss_variable(field.name, field.value)
          end
        end

        theme&.included_settings&.each do |name, value|
          next if name == "theme_uploads"
          contents << to_scss_variable(name, value)
        end

        Import.new("theme_variable.scss", source: contents)
      end

      register_import "category_backgrounds" do
        contents = +""
        Category.where('uploaded_background_id IS NOT NULL').each do |c|
          contents << category_css(c) if c.uploaded_background&.url.present?
        end

        Import.new("category_background.scss", source: contents)
      end

      register_import "embedded_theme" do
        next unless @theme_id

        theme_import(:common, :embedded_scss)
      end

      register_import "mobile_theme" do
        next unless @theme_id

        theme_import(:mobile, :scss)
      end

      register_import "desktop_theme" do
        next unless @theme_id

        theme_import(:desktop, :scss)
      end
    end

    register_imports!

    def self.import_color_definitions(theme_id)
      contents = +""
      DiscoursePluginRegistry.color_definition_stylesheets.each do |name, path|
        contents << "// Color definitions from #{name}\n\n"
        contents << File.read(path.to_s)
        contents << "\n\n"
      end

      theme_id ||= SiteSetting.default_theme_id
      resolved_ids = Theme.transform_ids([theme_id])

      if resolved_ids
        contents << " @import \"theme_variables\";"
        Theme.list_baked_fields(resolved_ids, :common, :color_definitions).each do |row|
          contents << "// Color definitions from #{Theme.find_by_id(theme_id)&.name}\n\n"
          contents << row.value
        end
      end
      contents
    end

    def self.import_wcag_overrides(color_scheme_id)
      if color_scheme_id && ColorScheme.find_by_id(color_scheme_id)&.is_wcag?
        return "@import \"wcag\";"
      end
      ""
    end

    def initialize(options)
      @theme = options[:theme]
      @theme_id = options[:theme_id]
      @theme_field = options[:theme_field]
      @color_scheme_id = options[:color_scheme_id]

      if @theme && !@theme_id
        # make up an id so other stuff does not bail out
        @theme_id = @theme.id || -1
      end
      @importable_theme_fields = {}
    end

    def import_files(files)
      files.map do |file|
        # we never want inline css imports, they are a mess
        # this tricks libsass so it imports inline instead
        if file =~ /\.css$/
          file = file[0..-5]
        end
        Import.new(file)
      end
    end

    def theme_import(target, attr)
      fields = theme.list_baked_fields(target, attr)

      fields.map do |field|
        value = field.value
        if value.present?
          filename = "theme_#{field.theme.id}/#{field.target_name}-#{field.name}-#{field.theme.name.parameterize}.scss"
          with_comment = <<~COMMENT
          // Theme: #{field.theme.name}
          // Target: #{field.target_name} #{field.name}
          // Last Edited: #{field.updated_at}

          #{value}
          COMMENT
          Import.new(filename, source: with_comment)
        end
      end.compact
    end

    def theme
      unless @theme
        @theme = (@theme_id && Theme.find(@theme_id)) || :nil
      end
      @theme == :nil ? nil : @theme
    end

    def theme_dir(import_theme_id)
      "theme_#{import_theme_id}"
    end

    def extract_theme_id(path)
      path[/^theme_([0-9]+)\//, 1]
    end

    def importable_theme_fields(import_theme_id)
      return {} unless theme && import_theme = Theme.find(import_theme_id)
      @importable_theme_fields[import_theme_id] ||= begin
        hash = {}
        import_theme.theme_fields.where(target_id: Theme.targets[:extra_scss]).each do |field|
          hash[field.name] = field.value
        end
        hash
      end
    end

    def match_theme_import(path, parent_path)
      # Only allow importing theme stylesheets from within stylesheets in the same theme
      return false unless theme && import_theme_id = extract_theme_id(parent_path) # Could be a child theme
      parent_dir, _ = File.split(parent_path)

      # Could be relative to the importing file, or relative to the root of the theme directory
      search_paths = [parent_dir, theme_dir(import_theme_id)].uniq
      search_paths.each do |search_path|
        resolved = Pathname.new("#{search_path}/#{path}").cleanpath.to_s # Remove unnecessary ./ and ../
        next unless resolved.start_with?("#{theme_dir(import_theme_id)}/")
        resolved_within_theme = resolved.sub(/^theme_[0-9]+\//, "")
        if importable_theme_fields(import_theme_id).keys.include?(resolved_within_theme)
          return resolved, importable_theme_fields(import_theme_id)[resolved_within_theme]
        end
      end
      false
    end

    def category_css(category)
      full_slug = category.full_slug.split("-")[0..-2].join("-")
      "body.category-#{full_slug} { background-image: url(#{upload_cdn_path(category.uploaded_background.url)}) }\n"
    end

    def font_css(font)
      contents = +""

      if font[:variants].present?
        font[:variants].each do |variant|
          src = variant[:src] ? variant[:src] : "asset-url(\"/fonts/#{variant[:filename]}?v=#{DiscourseFonts::VERSION}\") format(\"#{variant[:format]}\")"
          contents << <<~EOF
            @font-face {
              font-family: #{font[:name]};
              src: #{src};
              font-weight: #{variant[:weight]};
            }
          EOF
        end
      end

      contents
    end

    def to_scss_variable(name, value)
      escaped = SassC::Script::Value::String.quote(value, sass: true)
      "$#{name}: unquote(#{escaped});\n"
    end

    def imports(asset, parent_path)
      if callback = Importer.special_imports[asset]
        instance_eval(&callback)
      else
        path, source = match_theme_import(asset, parent_path)
        if path && source
          Import.new(path, source: source)
        else
          Import.new(asset + ".scss")
        end
      end
    end
  end
end