require 'json'

# this class converts the direct messages from a slack export to 
# a format wich can then be imported by mattermost
# author Daniel Schubert <mail@schubertdaniel.de>


class ImportDMS 
	def initialize()
		@dms = {}
		@users = {}

		self.xtract_users
		self.xtract_dms
	end
	
	def xtract_users()
		data = self.read_json('users.json')
		data.each do |d|
			@users.store( d["id"], d["name"])
		end
	end

	def xtract_dms()
		data = self.read_json('dms.json')
		data.each do |d|
			@dms.store( d["id"],d["members"])
		end
	end

	def read_json( file )
		f = File.open file
		d = JSON.load f
	end
	
	def get_usr_name( id )
		unless (id == nil) 
			@users.fetch(id)
		end
	end

	def cnvrt_ts( ts )
    # converts the slack timestamp to a mattermost timestamp
		t = ts.sub!(".", "")
		t[0,13]
	end

	def get_messages(chat_id)
		files = Dir.glob("#{chat_id}/*.json")
		chats = Array.new 

		files.each { |file|
			f = read_json( file )

			f.each { |m|
				n = self.get_usr_name( m["user"] )
				ts = self.cnvrt_ts( m["ts"] )
				#user,ts, test
				chats.push( [ts, n, m["text"]] )
			}
		}

		return chats
	end

	def create_json
		# version; required 		
		puts '{"type":"version","version":1}'
		
    @dms.each_key do |key| 
      #get user names
			user_names = []
			@dms.fetch(key).each do |u_id| 
				user_names.push( @users.fetch(u_id) )
			end	  
      self.create_channel_list(user_names)
      self.create_direct_messages(key, user_names)
    end
	end

  def create_direct_messages(key, user_names)
    #TODO : replies are output as normal messages; should be grouped as replies
    # create direct messages list
    m = get_messages(key)
    m.each do |msg|
      ml = {"type"=>"direct_post","direct_post"=>{"channel_members" => user_names, "user" => msg[1], "message" => msg[2], "create_at" => msg[0].to_i, "flagged_by" => nil, "reactions" => nil, "replies"=> nil, "attachments"=> nil } }.to_json
      puts ml
    end
  end

  def create_channel_list( user_names )
    cl = {"type" => "direct_channel", "direct_channel" => {"members" => user_names, "favorited_by" => nil,"header" => "" }}.to_json
    puts cl
  end

end

# usage
i = ImportDMS.new
i.create_json