--[[
    bot.lua
    The heart and sole of otouto, ie the init and main loop.

    Copyright 2016 topkecleon <drew@otou.to>
    This code is licensed under the GNU AGPLv3. See /LICENSE for details.
]]--

local bot = {}
local bindings -- Bot API bindings.
local utilities -- Miscellaneous and shared plugins.

bot.version = '3.14'

 -- Function to be run on start and reload.
function bot:init(config)

    assert(config.bot_api_key, 'You didn\'t set your bot token in config.lua!')

    bindings = require('otouto.bindings').init(config.bot_api_key)
    utilities = require('otouto.utilities')

    -- Fetch bot information. Try until it succeeds.
    repeat
        print('Fetching bot information...')
        self.info = bindings.getMe()
    until self.info
    self.info = self.info.result

    -- Load the "database"! ;)
    self.database_name = config.database_name or self.info.username .. '.db'
    if not self.database then
        self.database = utilities.load_data(self.database_name)
    end

    -- Migration code 1.13 -> 1.14
    -- "database.reminders" -> "database.remind"
    if self.database.version ~= '3.14' then
        self.database.remind = self.database.reminders
        self.database.reminders = nil
    end
    -- End migration code.

    -- Table to cache user info (usernames, IDs, etc).
    self.database.users = self.database.users or {}
    -- Table to store userdata (nicknames, lastfm usernames, etc).
    self.database.userdata = self.database.userdata or {}
    -- Table to store the IDs of blacklisted users.
    self.database.blacklist = self.database.blacklist or {}
    -- Save the bot's version in the database to make migration simpler.
    self.database.version = bot.version
    -- Add updated bot info to the user info cache.
    self.database.users[tostring(self.info.id)] = self.info

    -- All plugins go into self.plugins. Plugins which accept forwarded messages
    -- and messages from blacklisted users also go into self.panoptic_plugins.
    self.plugins = {}
    self.panoptic_plugins = {}
    for _, pname in ipairs(config.plugins) do
        local plugin = require('otouto.plugins.'..pname)
        table.insert(self.plugins, plugin)
        if plugin.init then plugin.init(self, config) end
        if plugin.panoptic then table.insert(self.panoptic_plugins, plugin) end
        if plugin.doc then
            plugin.doc = '<pre>'..utilities.html_escape(plugin.doc)..'</pre>'
        end
        if not plugin.triggers then plugin.triggers = {} end
    end

    print('@' .. self.info.username .. ', AKA ' .. self.info.first_name ..' ('..self.info.id..')')

    -- Set loop variables.
    self.last_update = self.last_update or 0 -- Update offset.
    self.last_cron = self.last_cron or os.date('%M') -- Last cron job.
    self.last_database_save = self.last_database_save or os.date('%H') -- Last db save.
    self.is_started = true

end

 -- Function to be run on each new message.
function bot:on_msg_receive(msg, config)

    -- Do not process old messages.
    if msg.date < os.time() - 5 then return end

    -- plugint is the array of plugins we'll check the message against.
    -- If the message is forwarded or from a blacklisted user, the bot will only
    -- check against panoptic plugins.
    local plugint = self.plugins
    local from_id_str = tostring(msg.from.id)

    -- Cache user info for those involved.
    self.database.users[from_id_str] = msg.from
    if msg.reply_to_message then
        self.database.users[tostring(msg.reply_to_message.from.id)] = msg.reply_to_message.from
    elseif msg.forward_from then
        -- Forwards only go to panoptic plugins.
        plugint = self.panoptic_plugins
        self.database.users[tostring(msg.forward_from.id)] = msg.forward_from
    elseif msg.new_chat_member then
        self.database.users[tostring(msg.new_chat_member.id)] = msg.new_chat_member
    elseif msg.left_chat_member then
        self.database.users[tostring(msg.left_chat_member.id)] = msg.left_chat_member
    end

    -- Messages from blacklisted users only go to panoptic plugins.
    if self.database.blacklist[from_id_str] then
        plugint = self.panoptic_plugins
    end

    -- If no text, use captions.
    msg.text = msg.text or msg.caption or ''
    msg.text_lower = msg.text:lower()
    if msg.reply_to_message then
        msg.reply_to_message.text = msg.reply_to_message.text or msg.reply_to_message.caption or ''
    end

    -- Support deep linking.
    if msg.text:match('^/start .+') then
        msg.text = config.cmd_pat .. utilities.input(msg.text)
        msg.text_lower = msg.text:lower()
    end

    -- Do the thing.
    for _, plugin in ipairs(plugint) do
        for _, trigger in ipairs(plugin.triggers) do
            if string.match(msg.text_lower, trigger) then
                local success, result = pcall(function()
                    return plugin.action(self, msg, config)
                end)
                if not success then
                    -- If the plugin has an error message, send it. If it does
                    -- not, use the generic one specified in config. If it's set
                    -- to false, do nothing.
                    if plugin.error then
                        utilities.send_reply(msg, plugin.error)
                    elseif plugin.error == nil then
                        utilities.send_reply(msg, config.errors.generic)
                    end
                    utilities.handle_exception(self, result, msg.from.id .. ': ' .. msg.text, config.log_chat)
                    return
                -- Continue if the return value is true.
                elseif result ~= true then
                    return
                end
            end
        end
    end
end

 -- main
function bot:run(config)
    bot.init(self, config)
    while self.is_started do
        -- Update loop.
        local res = bindings.getUpdates{ timeout = 20, offset = self.last_update + 1 }
        if res then
            -- Iterate over every new message.
            for _,v in ipairs(res.result) do
                self.last_update = v.update_id
                if v.message then
                    bot.on_msg_receive(self, v.message, config)
                end
            end
        else
            print('Connection error while fetching updates.')
        end

        -- Run cron jobs every minute.
        if self.last_cron ~= os.date('%M') then
            self.last_cron = os.date('%M')
            for i,v in ipairs(self.plugins) do
                if v.cron then -- Call each plugin's cron function, if it has one.
                    local result, err = pcall(function() v.cron(self, config) end)
                    if not result then
                        utilities.handle_exception(self, err, 'CRON: ' .. i, config.log_chat)
                    end
                end
            end
        end

        -- Save the "database" every hour.
        if self.last_database_save ~= os.date('%H') then
            self.last_database_save = os.date('%H')
            utilities.save_data(self.database_name, self.database)
        end
    end
    -- Save the database before exiting.
    utilities.save_data(self.database_name, self.database)
    print('Halted.')
end

return bot