require "http"
require "./utils.cr"

module Telepathy
    class Bot
        enum Control
            Done
        end

        def initialize(@api_token : String)
            @request_base = "https://api.telegram.org/bot#{@api_token}"
            @this_user = uninitialized User?
            @this_user = get_me
            @last_update_id = uninitialized Int64?
            @last_update_id = nil
            @command_hooks = {} of String => Update, Array(String) -> Void
            @message_hooks = [] of Update -> Void
            @poll_start_hooks = [] of -> Void
            @poll_end_hooks = [] of -> Void
            @poll_channel = Channel(Int64?|Control).new
            @update_channel = Channel(Array(Update)|Control).new
            @poll_running = false
        end

        def get_me
            Utils.get_me(@api_token)
        end

        def get_updates(timeout = 0)
            Utils.get_updates(@api_token, timeout, @last_update_id)
        end

        def send_message(chat_id : String | Int64, text : String,
                         parse_mode : Utils::ParseMode = Utils::ParseMode::Normal,
                         disable_web_preview : Bool = false,
                         disable_notification : Bool = false,
                         reply_to_message_id : Int64? = nil)
            Utils.send_message(@api_token, chat_id, text, 
                         parse_mode, disable_web_preview,
                         disable_notification, reply_to_message_id)
        end

        def send_photo(chat_id : String | Int64, photo : String | File, caption : String? = nil,
                       disable_notification : Bool = false,
                       reply_to_message_id : Int64? = nil)
            Utils.send_photo(@api_token, chat_id, photo, caption, disable_notification, reply_to_message_id)
        end

        def command(command_name, &block: Update, Array(String) -> Void)
            @command_hooks[command_name] = block
        end

        def message(&block: Update -> Void)
            @message_hooks.push(block)
        end

        def poll_start(&block: -> Void)
            @poll_start_hooks.push(block);
        end

        def poll_end(&block: -> Void)
            @poll_end_hooks.push(block);
        end

        private def process_updates(updates)
            updates.each do |update|
                if message = update.message
                    @message_hooks.each &.call(update)
                    if entity = message.entities.try { |it| it.first? }
                        text = message.text.as String
                        if entity.offset == 0 && entity.type == "bot_command"
                            divider_index = (text.index /\s|@/) || text.size
                            first_space_index = (text.index /\s/) || text.size
                            command = text[1...divider_index]
                            remaining = text[first_space_index..text.size]
                            params = remaining.empty? ? ([] of String) : (remaining[1...remaining.size].split ' ')
                            @command_hooks[command]?.try { |command| command.call(update, params) }
                        end
                    end
                end
            end
        end

        private def spawn_workers
            spawn do
                loop do
                    action = @poll_channel.receive
                    case action
                    when Int64?
                        @last_update_id = action.nil? ? @last_update_id : action + 1
                        @update_channel.send get_updates 10
                    when Control
                        break
                    end
                end
            end
            spawn do
                loop do
                    item = @update_channel.receive
                    case item
                    when Array(Update)
                        process_updates(item)
                        @poll_channel.send item.last?.try &.update_id
                    when Control
                        @poll_channel.send item
                        break
                    end
                end
            end
        end

        def poll
            if !@poll_running
                @poll_running = true
                spawn_workers
                @poll_channel.send nil
                @poll_start_hooks.each &.call
            end
        end

        def end_poll
            if @poll_running
                @poll_running = false
                @poll_channel.send Control::Done
                @poll_end_hooks.each &.call
            end
        end
    end
end