import path from "path";
import yaml from "js-yaml";

import fs from "fs";
const fsp = fs.promises;

import { Knub, logger, PluginError, Plugin } from "knub";
import { SimpleError } from "./SimpleError";

import DiscordRESTError from "eris/lib/errors/DiscordRESTError"; // tslint:disable-line
import DiscordHTTPError from "eris/lib/errors/DiscordHTTPError"; // tslint:disable-line

require("dotenv").config();

// Error handling
let recentPluginErrors = 0;
const RECENT_PLUGIN_ERROR_EXIT_THRESHOLD = 5;

let recentDiscordErrors = 0;
const RECENT_DISCORD_ERROR_EXIT_THRESHOLD = 5;

setInterval(() => (recentPluginErrors = Math.max(0, recentPluginErrors - 1)), 2500);
setInterval(() => (recentDiscordErrors = Math.max(0, recentDiscordErrors - 1)), 2500);

function errorHandler(err) {
  // tslint:disable:no-console
  console.error(err);

  if (err instanceof PluginError) {
    // Tolerate a few recent plugin errors before crashing
    if (++recentPluginErrors >= RECENT_PLUGIN_ERROR_EXIT_THRESHOLD) {
      console.error(`Exiting after ${RECENT_PLUGIN_ERROR_EXIT_THRESHOLD} plugin errors`);
      process.exit(1);
    }
  } else if (err instanceof DiscordRESTError || err instanceof DiscordHTTPError) {
    // Discord API errors, usually safe to just log instead of crash
    // We still bail if we get a ton of them in a short amount of time
    if (++recentDiscordErrors >= RECENT_DISCORD_ERROR_EXIT_THRESHOLD) {
      console.error(`Exiting after ${RECENT_DISCORD_ERROR_EXIT_THRESHOLD} API errors`);
      process.exit(1);
    }
  } else {
    // On other errors, crash immediately
    process.exit(1);
  }
  // tslint:enable:no-console
}

process.on("unhandledRejection", errorHandler);
process.on("uncaughtException", errorHandler);

// Verify required Node.js version
const REQUIRED_NODE_VERSION = "10.14.2";
const requiredParts = REQUIRED_NODE_VERSION.split(".").map(v => parseInt(v, 10));
const actualVersionParts = process.versions.node.split(".").map(v => parseInt(v, 10));
for (const [i, part] of actualVersionParts.entries()) {
  if (part > requiredParts[i]) break;
  if (part === requiredParts[i]) continue;
  throw new SimpleError(`Unsupported Node.js version! Must be at least ${REQUIRED_NODE_VERSION}`);
}

// Always use UTC internally
// This is also enforced for the database in data/db.ts
import moment from "moment-timezone";
moment.tz.setDefault("UTC");

import { Client } from "eris";
import { connect } from "./data/db";
import { availablePlugins, availableGlobalPlugins, basePlugins } from "./plugins/availablePlugins";
import { ZeppelinPlugin } from "./plugins/ZeppelinPlugin";
import { customArgumentTypes } from "./customArgumentTypes";
import { errorMessage, successMessage } from "./utils";
import { startUptimeCounter } from "./uptime";

// Run latest database migrations
logger.info("Running database migrations");
connect().then(async conn => {
  await conn.runMigrations();

  const client = new Client(`Bot ${process.env.TOKEN}`, {
    getAllUsers: true,
    restMode: true,
  });
  client.setMaxListeners(100);

  client.on("debug", message => {
    if (message.includes(" 429 ")) {
      logger.info(`[RATELIMITED] ${message}`);
    }
  });

  const bot = new Knub(client, {
    plugins: availablePlugins,
    globalPlugins: availableGlobalPlugins,

    options: {
      /**
       * Plugins are enabled if they...
       * - are base plugins, i.e. always enabled, or
       * - are dependencies of other enabled plugins, or
       * - are explicitly enabled in the guild config
       */
      getEnabledPlugins(guildId, guildConfig): string[] {
        const configuredPlugins = guildConfig.plugins || {};
        const pluginNames: string[] = Array.from(this.plugins.keys());
        const plugins: Array<typeof Plugin> = Array.from(this.plugins.values());
        const zeppelinPlugins: Array<typeof ZeppelinPlugin> = plugins.filter(
          p => p.prototype instanceof ZeppelinPlugin,
        ) as Array<typeof ZeppelinPlugin>;

        const enabledBasePlugins = pluginNames.filter(n => basePlugins.includes(n));
        const explicitlyEnabledPlugins = pluginNames.filter(pluginName => {
          return configuredPlugins[pluginName] && configuredPlugins[pluginName].enabled !== false;
        });
        const enabledPlugins = new Set([...enabledBasePlugins, ...explicitlyEnabledPlugins]);

        const pluginsEnabledAsDependencies = zeppelinPlugins.reduce((arr, pluginClass) => {
          if (!enabledPlugins.has(pluginClass.pluginName)) return arr;
          return arr.concat(pluginClass.dependencies);
        }, []);

        const finalEnabledPlugins = new Set([
          ...basePlugins,
          ...pluginsEnabledAsDependencies,
          ...explicitlyEnabledPlugins,
        ]);
        return Array.from(finalEnabledPlugins.values());
      },

      /**
       * Loads the requested config file from the config dir
       * TODO: Move to the database
       */
      async getConfig(id) {
        const configFile = id ? `${id}.yml` : "global.yml";
        const configPath = path.join("config", configFile);

        try {
          await fsp.access(configPath);
        } catch (e) {
          return {};
        }

        const yamlString = await fsp.readFile(configPath, { encoding: "utf8" });
        return yaml.safeLoad(yamlString);
      },

      logFn: (level, msg) => {
        if (level === "debug") return;
        // tslint:disable-next-line
        console.log(`[${level.toUpperCase()}] ${msg}`);
      },

      performanceDebug: {
        enabled: false,
        size: 30,
        threshold: 200,
      },

      customArgumentTypes,

      sendSuccessMessageFn(channel, body) {
        channel.createMessage(successMessage(body));
      },

      sendErrorMessageFn(channel, body) {
        channel.createMessage(errorMessage(body));
      },
    },
  });

  client.once("ready", () => {
    startUptimeCounter();
  });

  logger.info("Starting the bot");
  bot.run();
});