require 'mysql2'

require File.expand_path(File.dirname(__FILE__) + '/base.rb')

require 'htmlentities'
require 'tsort'
require 'set'
require 'optparse'
require 'etc'
require 'open3'

class ImportScripts::Smf2 < ImportScripts::Base

  def self.run
    options = Options.new
    begin
      options.parse!
    rescue Options::SettingsError => err
      $stderr.puts "Cannot load SMF settings: #{err.message}"
      exit 1
    rescue Options::Error => err
      $stderr.puts err.to_s.capitalize
      $stderr.puts options.usage
      exit 1
    end
    new(options).perform
  end

  attr_reader :options

  def initialize(options)
    if options.timezone.nil?
      $stderr.puts "No source timezone given and autodetection from PHP failed."
      $stderr.puts "Use -t option to specify correct source timezone:"
      $stderr.puts options.usage
      exit 1
    end

    super()
    @options = options

    begin
      Time.zone = options.timezone
    rescue ArgumentError
      $stderr.puts "Timezone name '#{options.timezone}' is invalid."
      exit 1
    end

    if options.database.blank?
      $stderr.puts "No database name given."
      $stderr.puts options.usage
      exit 1
    end
    if options.password == :ask
      require 'highline'
      $stderr.print "Enter password for MySQL database `#{options.database}`: "
      options.password = HighLine.new.ask('') {|q| q.echo = false }
    end

    @default_db_connection = create_db_connection
  end

  def execute
    import_groups
    import_users
    import_categories
    import_posts
    postprocess_posts
  end

  def import_groups
    puts '', 'creating groups'

    total = query(<<-SQL, as: :single)
      SELECT COUNT(*) FROM {prefix}membergroups
      WHERE min_posts = -1 AND group_type IN (1, 2)
    SQL

    create_groups(query(<<-SQL), total: total) {|group| group }
      SELECT id_group AS id, group_name AS name
      FROM {prefix}membergroups
      WHERE min_posts = -1 AND group_type IN (1, 2)
    SQL
  end

  GUEST_GROUP = -1
  MEMBER_GROUP = 0
  ADMIN_GROUP = 1
  MODERATORS_GROUP = 2

  def import_users
    puts '', 'creating users'
    total = query("SELECT COUNT(*) FROM {prefix}members", as: :single)

    create_users(query(<<-SQL), total: total) do |member|
      SELECT a.id_member, a.member_name, a.date_registered, a.real_name, a.email_address,
             a.is_activated, a.last_login, a.birthdate, a.member_ip, a.id_group, a.additional_groups,
             b.id_attach, b.file_hash, b.filename
      FROM {prefix}members AS a
      LEFT JOIN {prefix}attachments AS b ON a.id_member = b.id_member
    SQL
      group_ids = [ member[:id_group], *member[:additional_groups].split(',').map(&:to_i) ]
      create_time = Time.zone.at(member[:date_registered]) rescue Time.now
      last_seen_time = Time.zone.at(member[:last_login]) rescue nil
      ip_addr = IPAddr.new(member[:member_ip]) rescue nil
      {
        id: member[:id_member],
        username: member[:member_name],
        created_at: create_time,
        name: member[:real_name],
        email: member[:email_address],
        active: member[:is_activated] == 1,
        approved: member[:is_activated] == 1,
        last_seen_at: last_seen_time,
        date_of_birth: member[:birthdate],
        ip_address: ip_addr,
        admin: group_ids.include?(ADMIN_GROUP),
        moderator: group_ids.include?(MODERATORS_GROUP),

        post_create_action: proc do |user|
          user.update(created_at: create_time) if create_time < user.created_at
          GroupUser.transaction do
            group_ids.each do |gid|
              group_id = group_id_from_imported_group_id(gid) and
                GroupUser.find_or_create_by(user: user, group_id: group_id)
            end
          end
          if options.smfroot and member[:id_attach].present? and user.uploaded_avatar_id.blank?
            path = find_smf_attachment_path(member[:id_attach], member[:file_hash], member[:filename]) and begin
              upload = create_upload(user.id, path, member[:filename])
              if upload.persisted?
                user.update(uploaded_avatar_id: upload.id)
              end
            rescue SystemCallError => err
              puts "Could not import avatar: #{err.message}"
            end
          end
        end
      }
    end
  end

  def import_categories
    create_categories(query(<<-SQL)) do |board|
      SELECT id_board, id_parent, name, description, member_groups
      FROM {prefix}boards
      ORDER BY id_parent ASC, id_board ASC
    SQL
      parent_id = category_id_from_imported_category_id(board[:id_parent]) if board[:id_parent] > 0
      groups = (board[:member_groups] || "").split(/,/).map(&:to_i)
      restricted = !groups.include?(GUEST_GROUP) && !groups.include?(MEMBER_GROUP)
      {
        id: board[:id_board],
        name: board[:name],
        description: board[:description],
        parent_category_id: parent_id,
        post_create_action: restricted && proc do |category|
          category.update(read_restricted: true)
          groups.each do |imported_group_id|
            group_id = group_id_from_imported_group_id(imported_group_id) and
            CategoryGroup.find_or_create_by(category: category, group_id: group_id) do |cg|
              cg.permission_type = CategoryGroup.permission_types[:full]
            end
          end
        end,
      }
    end
  end

  def import_posts
    puts '', 'creating posts'
    spinner = %w(/ - \\ |).cycle
    total = query("SELECT COUNT(*) FROM {prefix}messages", as: :single)
    PostCreator.class_eval do
      def guardian
        @guardian ||= if opts[:import_mode]
          @@system_guardian ||= Guardian.new(Discourse.system_user)
        else
          Guardian.new(@user)
        end
      end
    end

    topics = Enumerator.new do |y|
      last_topic_id = nil
      topic_messages = nil
      query("SELECT id_msg, id_topic, body FROM {prefix}messages ORDER BY id_topic ASC, id_msg ASC") do |message|
        if last_topic_id != message[:id_topic]
          y << topic_messages
          last_topic_id = message[:id_topic]
          topic_messages = [ message ]
        else
          topic_messages << message
        end
      end
      y << topic_messages
    end

    graph = MessageDependencyGraph.new
    topics.each do |messages|
      next unless messages.present?
      (messages.reverse << nil).each_cons(2) do |message, prev|
        graph.add_message(message[:id_msg], prev ? prev[:id_msg] : nil,
          extract_quoted_message_ids(message[:body]).to_a)
      end
      print "\r#{spinner.next}"
    end

    begin
      cycles = graph.cycles
      print "\r#{spinner.next}"
      cycles.each do |cycle|
        candidate = cycle.detect {|n| ((cycle - [n]) & n.quoted).present? }
        candidate.ignore_quotes = true
      end
    end while cycles.present?
    message_order = graph.tsort
    print "\r#{spinner.next}"

    query(<<-SQL, as: :array)
      CREATE TEMPORARY TABLE {prefix}import_message_order (
        message_id int(11) NOT NULL,
        message_order int(11) NOT NULL AUTO_INCREMENT,
        ignore_quotes tinyint(1) NOT NULL,
        PRIMARY KEY (message_id),
        UNIQUE KEY message_order (message_order)
      ) ENGINE=MEMORY
    SQL
    message_order.each_slice(100) do |nodes|
      query(<<-SQL, as: :array)
        INSERT INTO {prefix}import_message_order (message_id, ignore_quotes)
        VALUES #{ nodes.map {|n| "(#{n.id}, #{n.ignore_quotes? ? 1 : 0})" }.join(',') }
      SQL
      print "\r#{spinner.next}"
    end

    db2 = create_db_connection

    create_posts(query(<<-SQL), total: total) do |message|
      SELECT m.id_msg, m.id_topic, m.id_member, m.poster_time, m.body, o.ignore_quotes,
             m.subject, t.id_board, t.id_first_msg, COUNT(a.id_attach) AS attachment_count
      FROM {prefix}messages AS m
      LEFT JOIN {prefix}import_message_order AS o ON o.message_id = m.id_msg
      LEFT JOIN {prefix}topics AS t ON t.id_topic = m.id_topic
      LEFT JOIN {prefix}attachments AS a ON a.id_msg = m.id_msg AND a.attachment_type = 0
      GROUP BY m.id_msg
      ORDER BY o.message_order ASC
    SQL
      skip = false
      ignore_quotes = (message[:ignore_quotes] == 1)
      post = {
        id: message[:id_msg],
        user_id: user_id_from_imported_user_id(message[:id_member]) || -1,
        created_at: Time.zone.at(message[:poster_time]),
        post_create_action: ignore_quotes && proc do |post|
          post.custom_fields['import_rebake'] = 't'
          post.save
        end
      }
      if message[:id_msg] == message[:id_first_msg]
        post[:category] = category_id_from_imported_category_id(message[:id_board])
        post[:title] = decode_entities(message[:subject])
      else
        parent = topic_lookup_from_imported_post_id(message[:id_first_msg])
        if parent
          post[:topic_id] = parent[:topic_id]
        else
          puts "Parent post #{message[:id_first_msg]} doesn't exist. Skipping #{message[:id_msg]}: #{message[:subject][0..40]}"
          skip = true
        end
      end
      next nil if skip

      attachments = message[:attachment_count] == 0 ? [] : query(<<-SQL, connection: db2, as: :array)
        SELECT id_attach, file_hash, filename FROM {prefix}attachments
        WHERE attachment_type = 0 AND id_msg = #{message[:id_msg]}
        ORDER BY id_attach ASC
      SQL
      attachments.map! {|a| import_attachment(post, a) rescue (puts $! ; nil) }
      post[:raw] = convert_message_body(message[:body], attachments, ignore_quotes: ignore_quotes)
      next post
    end
  end

  def import_attachment(post, attachment)
    path = find_smf_attachment_path(attachment[:id_attach], attachment[:file_hash], attachment[:filename])
    raise "Attachment for post #{post[:id]} failed: #{attachment[:filename]}" unless path.present?
    upload = create_upload(post[:user_id], path, attachment[:filename])
    raise "Attachment for post #{post[:id]} failed: #{upload.errors.full_messages.join(', ')}" unless upload.persisted?
    return upload
  rescue SystemCallError => err
    raise "Attachment for post #{post[:id]} failed: #{err.message}"
  end

  def postprocess_posts
    puts '', 'rebaking posts'

    tags = PostCustomField.where(name: 'import_rebake', value: 't')
    tags_total = tags.count
    tags_done = 0

    tags.each do |tag|
      post = tag.post
      Post.transaction do
        post.raw = convert_quotes(post.raw)
        post.rebake!
        post.save
        tag.destroy!
      end
      print_status(tags_done += 1, tags_total)
    end
  end

  private

  def create_db_connection
    Mysql2::Client.new(host: options.host, username: options.username,
      password: options.password, database: options.database)
  end

  def query(sql, **opts, &block)
    db = opts[:connection] || @default_db_connection
    return __query(db, sql).to_a                       if opts[:as] == :array
    return __query(db, sql, as: :array).first[0]       if opts[:as] == :single
    return __query(db, sql, stream: true).each(&block) if block_given?
    return __query(db, sql, stream: true)
  end

  def __query(db, sql, **opts)
    db.query(sql.gsub('{prefix}', options.prefix),
      {symbolize_keys: true, cache_rows: false}.merge(opts))
  end

  TRTR_TABLE = begin
    from = "ŠŽšžŸÀÁÂÃÄÅÇÈÉÊËÌÍÎÏÑÒÓÔÕÖØÙÚÛÜÝàáâãäåçèéêëìíîïñòóôõöøùúûüýÿ"
    to = "SZszYAAAAAACEEEEIIIINOOOOOOUUUUYaaaaaaceeeeiiiinoooooouuuuyy"
    from.chars.zip(to.chars)
  end

  def find_smf_attachment_path(attachment_id, file_hash, filename)
    cleaned_name = filename.dup
    TRTR_TABLE.each {|from,to| cleaned_name.gsub!(from, to) }
    cleaned_name.gsub!(/\s/, '_')
    cleaned_name.gsub!(/[^\w_\.\-]/, '')
    legacy_name = "#{attachment_id}_#{cleaned_name.gsub('.', '_')}#{Digest::MD5.hexdigest(cleaned_name)}"

    [ filename, "#{attachment_id}_#{file_hash}", legacy_name ]
      .map {|name| File.join(options.smfroot, 'attachments', name) }
      .detect {|file| File.exists?(file) }
  end

  def decode_entities(*args)
    (@html_entities ||= HTMLEntities.new).decode(*args)
  end

  def convert_message_body(body, attachments = [], **opts)
    body = decode_entities(body.gsub(/<br\s*\/>/, "\n"))
    body.gsub!(ColorPattern, '\k<inner>')
    body.gsub!(ListPattern) do |s|
      params = parse_tag_params($~[:params])
      tag = params['type'] == 'decimal' ? 'ol' : 'ul'
      "\n[#{tag}]#{$~[:inner].strip}[/#{tag}]\n"
    end
    body.gsub!(XListPattern) do |s|
      r = "\n[ul]"
      s.lines.each {|l| r << '[li]' << l.strip.sub(/^\[x\]\s*/, '') << '[/li]' }
      r << "[/ul]\n"
    end

    if attachments.present?
      use_count = Hash.new(0)
      AttachmentPatterns.each do |p|
        pattern, emitter = *p
        body.gsub!(pattern) do |s|
          next s unless (num = $~[:num].to_i - 1) >= 0
          next s unless (upload = attachments[num]).present?
          use_count[num] += 1
          instance_exec(upload, &emitter)
        end
      end
      if use_count.keys.length < attachments.select(&:present?).length
        body << "\n\n---"
        attachments.each_with_index do |upload, num|
          if upload.present? and use_count[num] == 0
            body << ( "\n\n" + get_upload_markdown(upload) )
          end
        end
      end
    end

    return opts[:ignore_quotes] ? body : convert_quotes(body)
  end

  def v8
    @ctx ||= begin
      ctx = PrettyText.create_new_context
      PrettyText.decorate_context(ctx)
      # provides toHumanSize but restores I18n.t which we need to fix again
      ctx.load(Rails.root + "app/assets/javascripts/locales/i18n.js")
      helper = PrettyText::Helpers.new
      ctx['I18n']['t'] = proc {|_,key,opts| helper.t(key, opts) }
      # from i18n_helpers.js -- can't load it directly because Ember is missing
      ctx.eval(<<-'end')
        var oldI18ntoHumanSize = I18n.toHumanSize;
        I18n.toHumanSize = function(number, options) {
          options = options || {};
          options.format = I18n.t("number.human.storage_units.format");
          return oldI18ntoHumanSize.apply(this, [number, options]);
        };
      end
      ctx
    end
  end

  def get_upload_markdown(upload)
    @func ||= v8.eval("Discourse.Utilities.getUploadMarkdown")
    return @func.call(upload).to_s
  end

  def convert_quotes(body)
    body.to_s.gsub(QuotePattern) do |s|
      inner = $~[:inner].strip
      params = parse_tag_params($~[:params])
      if params['author'].present?
        quote = "[quote=\"#{params['author']}"
        if QuoteParamsPattern =~ params['link']
          tl = topic_lookup_from_imported_post_id($~[:msg].to_i)
          quote << ", post:#{tl[:post_number]}, topic:#{tl[:topic_id]}" if tl
        end
        quote << "\"]#{inner}[/quote]"
      else
        "<blockquote>#{inner}</blockquote>"
      end
    end
  end

  def extract_quoted_message_ids(body)
    Set.new.tap do |quoted|
      body.scan(/\[quote\s+([^\]]+)\s*\]/) do |params|
        params = parse_tag_params(params)
        if params.has_key?("link")
          match = QuoteParamsPattern.match(params["link"])
          quoted << match[:msg].to_i if match
        end
      end
    end
  end

  # param1=value1=still1 value1 param2=value2 ...
  # => {'param1' => 'value1=still1 value1', 'param2' => 'value2 ...'}
  def parse_tag_params(params)
    params.to_s.strip.scan(/(?<param>\w+)=(?<value>(?:(?>\S+)|\s+(?!\w+=))*)/).
      inject({}) {|h,e| h[e[0]] = e[1]; h }
  end

  class << self
    private

    # [tag param=value param2=value2]
    #   text
    #   [tag nested=true]text[/tag]
    # [/tag]
    # => match[:params] == 'param=value param2=value2'
    #    match[:inner] == "\n  text\n  [tag nested=true]text[/tag]\n"
    def build_nested_tag_regex(ltag, rtag = nil)
      rtag ||= '/'+ltag
      %r{
        \[#{ltag}(?-x:[ =](?<params>[^\]]*))?\]            # consume open tag, followed by...
          (?<inner>(?:
            (?> [^\[]+ )                                   # non-tags, or...
            |
            \[(?! #{ltag}(?-x:[ =][^\]]*)?\] | #{rtag}\])  # different tags, or ...
            |
            (?<re>                                         # recursively matched tags of the same kind
              \[#{ltag}(?-x:[ =][^\]]*)?\]
                (?:
                  (?> [^\[]+ )
                  |
                  \[(?! #{ltag}(?-x:[ =][^\]]*)?\] | #{rtag}\])
                  |
                  \g<re>                                   # recursion here
                )*
              \[#{rtag}\]
            )
          )*)
        \[#{rtag}\]
      }x
    end
  end

  QuoteParamsPattern = /^topic=(?<topic>\d+).msg(?<msg>\d+)#msg\k<msg>$/
  XListPattern = /(?<xblock>(?>^\[x\]\s*(?<line>.*)$\n?)+)/
  QuotePattern = build_nested_tag_regex('quote')
  ColorPattern = build_nested_tag_regex('color')
  ListPattern = build_nested_tag_regex('list')
  AttachmentPatterns = [
    [/^\[attach(?:|img|url|mini)=(?<num>\d+)\]$/, ->(u) { "\n"+get_upload_markdown(u)+"\n" }],
    [/\[attach(?:|img|url|mini)=(?<num>\d+)\]/, ->(u) { get_upload_markdown(u) }]
  ]


  # Provides command line options and parses the SMF settings file.
  class Options

    class Error < StandardError ; end
    class SettingsError < Error ; end

    def parse!(args = ARGV)
      raise Error, 'not enough arguments' if ARGV.empty?
      begin
        parser.parse!(args)
      rescue OptionParser::ParseError => err
        raise Error, err.message
      end
      raise Error, 'too many arguments' if args.length > 1
      self.smfroot = args.first
      read_smf_settings if self.smfroot

      self.host ||= 'localhost'
      self.username ||= Etc.getlogin
      self.prefix ||= 'smf_'
      self.timezone ||= get_php_timezone
    end

    def usage
      parser.to_s
    end

    attr_accessor :host
    attr_accessor :username
    attr_accessor :password
    attr_accessor :database
    attr_accessor :prefix
    attr_accessor :smfroot
    attr_accessor :timezone

    private

    def get_php_timezone
      phpinfo, status = Open3.capture2('phpnope', '-i')
      phpinfo.lines.each do |line|
        key, *vals = line.split(' => ').map(&:strip)
        break vals[0] if key == 'Default timezone'
      end
    rescue Errno::ENOENT
      $stderr.puts "Error: PHP CLI executable not found"
    end

    def read_smf_settings
      settings = File.join(self.smfroot, 'Settings.php')
      IO.readlines(settings).each do |line|
        next unless m = /\$([a-z_]+)\s*=\s*['"](.+?)['"]\s*;\s*((#|\/\/).*)?$/.match(line)
        case m[1]
        when 'db_server' then self.host ||= m[2]
        when 'db_user'   then self.username ||= m[2]
        when 'db_passwd' then self.password ||= m[2]
        when 'db_name'   then self.database ||= m[2]
        when 'db_prefix' then self.prefix ||= m[2]
        end
      end
    rescue => err
      raise SettingsError, err.message unless self.database
    end

    def parser
      @parser ||= OptionParser.new(nil, 12) do |o|
        o.banner = "Usage:\t#{File.basename($0)} <SMFROOT> [options]\n"
        o.banner << "\t#{File.basename($0)} -d <DATABASE> [options]"
        o.on('-h HOST', :REQUIRED, "MySQL server hostname [\"#{self.host}\"]") {|s| self.host = s }
        o.on('-u USER', :REQUIRED, "MySQL username [\"#{self.username}\"]") {|s| self.username = s }
        o.on('-p [PASS]', :OPTIONAL, 'MySQL password. Without argument, reads password from STDIN.') {|s| self.password = s || :ask }
        o.on('-d DBNAME', :REQUIRED, 'Name of SMF database') {|s| self.database = s }
        o.on('-f PREFIX', :REQUIRED, "Table names prefix [\"#{self.prefix}\"]") {|s| self.prefix = s }
        o.on('-t TIMEZONE', :REQUIRED, 'Timezone used by SMF2 [auto-detected from PHP]') {|s| self.timezone = s }
      end
    end

  end #Options


  # Framework around TSort, used to build a dependency graph over messages
  # to find and solve cyclic quotations.
  class MessageDependencyGraph
    include TSort

    def initialize
      @nodes = {}
    end

    def [](key)
      @nodes[key]
    end

    def add_message(id, prev = nil, quoted = [])
      @nodes[id] = Node.new(self, id, prev, quoted)
    end

    def tsort_each_node(&block)
      @nodes.each_value(&block)
    end

    def tsort_each_child(node, &block)
      node.dependencies.each(&block)
    end

    def cycles
      strongly_connected_components.select {|c| c.length > 1 }.to_a
    end


    class Node
      attr_reader :id

      def initialize(graph, id, prev = nil, quoted = [])
        @graph = graph
        @id = id
        @prev = prev
        @quoted = quoted
      end

      def prev
        @graph[@prev]
      end

      def quoted
        @quoted.map {|id| @graph[id] }.reject(&:nil?)
      end

      def ignore_quotes?
        !!@ignore_quotes
      end

      def ignore_quotes=(value)
        @ignore_quotes = !!value
        @dependencies = nil
      end

      def dependencies
        @dependencies ||= Set.new.tap do |deps|
          deps.merge(quoted) unless ignore_quotes?
          deps << prev if prev.present?
        end.to_a
      end

      def hash
        @id.hash
      end

      def eql?(other)
        @id.eql?(other)
      end

      def inspect
        "#<#{self.class.name}: id=#{id.inspect}, prev=#{safe_id(@prev)}, quoted=[#{@quoted.map(&method(:safe_id)).join(', ')}]>"
      end

      private

      def safe_id(id)
        @graph[id].present? ? @graph[id].id.inspect : "(#{id})"
      end
    end #Node

  end #MessageDependencyGraph

end

ImportScripts::Smf2.run
