require_dependency 'theme_settings_parser'
require_dependency 'theme_translation_parser'
require_dependency 'theme_javascript_compiler'

class ThemeField < ActiveRecord::Base

  belongs_to :upload
  has_one :javascript_cache, dependent: :destroy

  scope :find_by_theme_ids, ->(theme_ids) {
    return none unless theme_ids.present?

    where(theme_id: theme_ids)
      .joins(
        "JOIN (
          SELECT #{theme_ids.map.with_index { |id, idx| "#{id.to_i} AS theme_id, #{idx} AS theme_sort_column" }.join(" UNION ALL SELECT ")}
        ) as X ON X.theme_id = theme_fields.theme_id")
      .order("theme_sort_column")
  }

  scope :find_locale_fields, ->(theme_ids, locale_codes) {
    return none unless theme_ids.present? && locale_codes.present?

    find_by_theme_ids(theme_ids)
      .where(target_id: Theme.targets[:translations], name: locale_codes)
      .joins(self.sanitize_sql_array([
        "JOIN (
          SELECT * FROM (VALUES #{locale_codes.map { "(?)" }.join(",")}) as Y (locale_code, locale_sort_column)
        ) as Y ON Y.locale_code = theme_fields.name",
        *locale_codes.map.with_index { |code, index| [code, index] }
      ]))
      .reorder("X.theme_sort_column", "Y.locale_sort_column")
  }

  scope :find_first_locale_fields, ->(theme_ids, locale_codes) {
    find_locale_fields(theme_ids, locale_codes)
      .select("DISTINCT ON (X.theme_sort_column) *")
  }

  def self.types
    @types ||= Enum.new(html: 0,
                        scss: 1,
                        theme_upload_var: 2,
                        theme_color_var: 3, # No longer used
                        theme_var: 4, # No longer used
                        yaml: 5)
  end

  def self.theme_var_type_ids
    @theme_var_type_ids ||= [2]
  end

  def self.force_recompilation!
    find_each do |field|
      field.compiler_version = 0
      field.ensure_baked!
    end
  end

  validates :name, format: { with: /\A[a-z_][a-z0-9_-]*\z/i },
                   if: Proc.new { |field| ThemeField.theme_var_type_ids.include?(field.type_id) }

  COMPILER_VERSION = 9

  belongs_to :theme

  def process_html(html)
    errors = []
    javascript_cache || build_javascript_cache

    js_compiler = ThemeJavascriptCompiler.new(theme_id)

    doc = Nokogiri::HTML.fragment(html)

    doc.css('script[type="text/x-handlebars"]').each do |node|
      name = node["name"] || node["data-template-name"] || "broken"
      is_raw = name =~ /\.raw$/
      hbs_template = node.inner_html

      begin
        if is_raw
          js_compiler.append_raw_template(name, hbs_template)
        else
          js_compiler.append_ember_template(name, hbs_template)
        end
      rescue ThemeJavascriptCompiler::CompileError => ex
        errors << ex.message
      end

      node.remove
    end

    doc.css('script[type="text/discourse-plugin"]').each do |node|
      next unless node['version'].present?
      begin
        js_compiler.append_plugin_script(node.inner_html, node['version'])
      rescue ThemeJavascriptCompiler::CompileError => ex
        errors << ex.message
      end

      node.remove
    end

    doc.css('script').each do |node|
      next unless inline_javascript?(node)
      js_compiler.append_raw_script(node.inner_html)
      node.remove
    end

    errors.each do |error|
      js_compiler.append_js_error(error)
    end

    js_compiler.prepend_settings(theme.cached_settings) if js_compiler.content.present? && theme.cached_settings.present?
    javascript_cache.content = js_compiler.content
    javascript_cache.save!

    doc.add_child("<script src='#{javascript_cache.url}'></script>") if javascript_cache.content.present?
    [doc.to_s, errors&.join("\n")]
  end

  def raw_translation_data(internal: false)
    # Might raise ThemeTranslationParser::InvalidYaml
    ThemeTranslationParser.new(self, internal: internal).load
  end

  def translation_data(with_overrides: true, internal: false)
    fallback_fields = theme.theme_fields.find_locale_fields([theme.id], I18n.fallbacks[name])

    fallback_data = fallback_fields.each_with_index.map do |field, index|
      begin
        field.raw_translation_data(internal: internal)
      rescue ThemeTranslationParser::InvalidYaml
        # If this is the locale with the error, raise it.
        # If not, let the other theme_field raise the error when it processes itself
        raise if field.id == id
        {}
      end
    end

    # TODO: Deduplicate the fallback data in the same way as JSLocaleHelper#load_translations_merged
    #       this would reduce the size of the payload, without affecting functionality
    data = {}
    fallback_data.each { |hash| data.merge!(hash) }
    overrides = theme.translation_override_hash.deep_symbolize_keys
    data.deep_merge!(overrides) if with_overrides
    data
  end

  def process_translation
    errors = []
    javascript_cache || build_javascript_cache
    js_compiler = ThemeJavascriptCompiler.new(theme_id)
    begin
      data = translation_data

      js = <<~JS
        /* Translation data for theme #{self.theme_id} (#{self.name})*/
        const data = #{data.to_json};

        for (let lang in data){
          let cursor = I18n.translations;
          for (let key of [lang, "js", "theme_translations"]){
            cursor = cursor[key] = cursor[key] || {};
          }
          cursor[#{self.theme_id}] = data[lang];
        }
      JS

      js_compiler.append_plugin_script(js, 0)
    rescue ThemeTranslationParser::InvalidYaml => e
      errors << e.message
    end

    javascript_cache.content = js_compiler.content
    javascript_cache.save!
    doc = ""
    doc = "<script src='#{javascript_cache.url}'></script>" if javascript_cache.content.present?
    [doc, errors&.join("\n")]
  end

  def validate_yaml!
    return unless self.name == "yaml"

    errors = []
    begin
      ThemeSettingsParser.new(self).load do |name, default, type, opts|
        setting = ThemeSetting.new(name: name, data_type: type, theme: theme)
        translation_key = "themes.settings_errors"

        if setting.invalid?
          setting.errors.details.each_pair do |attribute, _errors|
            _errors.each do |hash|
              errors << I18n.t("#{translation_key}.#{attribute}_#{hash[:error]}", name: name)
            end
          end
        end

        if default.nil?
          errors << I18n.t("#{translation_key}.default_value_missing", name: name)
        end

        if (min = opts[:min]) && (max = opts[:max])
          unless ThemeSetting.value_in_range?(default, (min..max), type)
            errors << I18n.t("#{translation_key}.default_out_range", name: name)
          end
        end

        unless ThemeSetting.acceptable_value_for_type?(default, type)
          errors << I18n.t("#{translation_key}.default_not_match_type", name: name)
        end
      end
    rescue ThemeSettingsParser::InvalidYaml => e
      errors << e.message
    end

    self.error = errors.join("\n").presence
  end

  def self.guess_type(name:, target:)
    if html_fields.include?(name.to_s)
      types[:html]
    elsif scss_fields.include?(name.to_s)
      types[:scss]
    elsif name.to_s == "yaml" || target.to_s == "translations"
      types[:yaml]
    end
  end

  def self.html_fields
    @html_fields ||= %w(body_tag head_tag header footer after_header)
  end

  def self.scss_fields
    @scss_fields ||= %w(scss embedded_scss)
  end

  def ensure_baked!
    if ThemeField.html_fields.include?(self.name) || translation = Theme.targets[:translations] == self.target_id
      if !self.value_baked || compiler_version != COMPILER_VERSION
        self.value_baked, self.error = translation ? process_translation : process_html(self.value)
        self.error = nil unless self.error.present?
        self.compiler_version = COMPILER_VERSION

        if self.will_save_change_to_value_baked? ||
           self.will_save_change_to_compiler_version? ||
           self.will_save_change_to_error?

          self.update_columns(value_baked: value_baked,
                              compiler_version: compiler_version,
                              error: error)
        end
      end
    end
  end

  def ensure_scss_compiles!
    if ThemeField.scss_fields.include?(self.name)
      begin
        Stylesheet::Compiler.compile("@import \"theme_variables\"; @import \"theme_field\";",
                                     "theme.scss",
                                     theme_field: self.value.dup,
                                     theme: self.theme
                                    )
        self.error = nil unless error.nil?
      rescue SassC::SyntaxError => e
        self.error = e.message unless self.destroyed?
      end

      if will_save_change_to_error?
        update_columns(error: self.error)
      end
    end
  end

  def target_name
    Theme.targets.invert[target_id].to_s
  end

  class ThemeFileMatcher
    OPTIONS = %i{name type target}
    # regex: used to match file names to fields (import).
    #        can contain named capture groups for name/type/target
    # canonical: a lambda which converts name/type/target
    #            to filename (export)
    # targets/names/types: can be nil if any value is allowed
    #                          single value
    #                          array of allowed values
    def initialize(regex:, canonical:, targets:, names:, types:)
      @allowed_values = {}
      @allowed_values[:names] = Array(names) if names
      @allowed_values[:targets] = Array(targets) if targets
      @allowed_values[:types] = Array(types) if types
      @canonical = canonical
      @regex = regex
    end

    def opts_from_filename(filename)
      match = @regex.match(filename)
      return false unless match
      hash = {}
      OPTIONS.each do |option|
        plural = :"#{option}s"
        hash[option] = @allowed_values[plural][0] if @allowed_values[plural].length == 1
        hash[option] = match[option] if hash[option].nil?
      end
      hash
    end

    def filename_from_opts(opts)
      is_match = OPTIONS.all? do |option|
        plural = :"#{option}s"
        next true if @allowed_values[plural] == nil # Allows any value
        next true if @allowed_values[plural].include?(opts[option]) # Value is allowed
      end
      is_match ? @canonical.call(opts) : nil
    end
  end

  FILE_MATCHERS = [
    ThemeFileMatcher.new(regex: /^(?<target>(?:mobile|desktop|common))\/(?<name>(?:head_tag|header|after_header|body_tag|footer))\.html$/,
                         targets: [:mobile, :desktop, :common], names: ["head_tag", "header", "after_header", "body_tag", "footer"], types: :html,
                         canonical: -> (h) { "#{h[:target]}/#{h[:name]}.html" }),
    ThemeFileMatcher.new(regex: /^(?<target>(?:mobile|desktop|common))\/(?:\k<target>)\.scss$/,
                         targets: [:mobile, :desktop, :common], names: "scss", types: :scss,
                         canonical: -> (h) { "#{h[:target]}/#{h[:target]}.scss" }),
    ThemeFileMatcher.new(regex: /^common\/embedded\.scss$/,
                         targets: :common, names: "embedded_scss", types: :scss,
                         canonical: -> (h) { "common/embedded.scss" }),
    ThemeFileMatcher.new(regex: /^settings\.ya?ml$/,
                         names: "yaml", types: :yaml, targets: :settings,
                         canonical: -> (h) { "settings.yml" }),
    ThemeFileMatcher.new(regex: /^locales\/(?<name>(?:#{I18n.available_locales.join("|")}))\.yml$/,
                         names: I18n.available_locales.map(&:to_s), types: :yaml, targets: :translations,
                         canonical: -> (h) { "locales/#{h[:name]}.yml" }),
    ThemeFileMatcher.new(regex: /(?!)/, # Never match uploads by filename, they must be named in about.json
                         names: nil, types: :theme_upload_var, targets: :common,
                         canonical: -> (h) { "assets/#{h[:filename]}" }),
  ]

  # For now just work for standard fields
  def file_path
    FILE_MATCHERS.each do |matcher|
      if filename = matcher.filename_from_opts(target: target_name.to_sym,
                                               name: name,
                                               type: ThemeField.types[type_id],
                                               filename: upload&.original_filename)
        return filename
      end
    end
    nil # Not a file (e.g. a theme variable/color)
  end

  def self.opts_from_file_path(filename)
    FILE_MATCHERS.each do |matcher|
      if opts = matcher.opts_from_filename(filename)
        return opts
      end
    end
    nil
  end

  before_save do
    validate_yaml!

    if will_save_change_to_value? && !will_save_change_to_value_baked?
      self.value_baked = nil
    end
  end

  after_commit do
    ensure_baked!
    ensure_scss_compiles!
    theme.clear_cached_settings!

    Stylesheet::Manager.clear_theme_cache! if self.name.include?("scss")
    CSP::Extension.clear_theme_extensions_cache! if name == 'yaml'

    # TODO message for mobile vs desktop
    MessageBus.publish "/header-change/#{theme.id}", self.value if theme && self.name == "header"
    MessageBus.publish "/footer-change/#{theme.id}", self.value if theme && self.name == "footer"
  end

  private

  JAVASCRIPT_TYPES = %w(
    text/javascript
    application/javascript
    application/ecmascript
  )

  def inline_javascript?(node)
    if node['src'].present?
      false
    elsif node['type'].present?
      JAVASCRIPT_TYPES.include?(node['type'].downcase)
    else
      true
    end
  end
end

# == Schema Information
#
# Table name: theme_fields
#
#  id               :integer          not null, primary key
#  theme_id         :integer          not null
#  target_id        :integer          not null
#  name             :string(30)       not null
#  value            :text             not null
#  value_baked      :text
#  created_at       :datetime         not null
#  updated_at       :datetime         not null
#  compiler_version :integer          default(0), not null
#  error            :string
#  upload_id        :integer
#  type_id          :integer          default(0), not null
#
# Indexes
#
#  theme_field_unique_index  (theme_id,target_id,type_id,name) UNIQUE
#