import {
  Plugin,
  EventListener,
  Configurable,
  DependencyLoad,
  DependencyUnload
} from '@squeebot/core/lib/plugin';

import { EMessageType, IMessage, IMessageTarget } from '@squeebot/core/lib/types';

import { fullIDMatcher } from '@squeebot/core/lib/common';

import { logger } from '@squeebot/core/lib/core';
import { IChannel } from '@squeebot/core/lib/channel';

declare type Matcher = (msg: IMessage) => any;

interface CommandSpec {
  name: string;
  plugin: string;
  description?: string;
  usage?: string;
  source?: string | string[] | Matcher;
  tags?: string[];
  aliases?: string[];
  alias?: string;
  match?: string | Matcher;
  hidden?: boolean;
  permissions?: string[];
  tempargv?: any[];
  execute(msg: IMessage, command: CommandSpec, prefix: string, ...args: any[]): Promise<boolean>;
}

interface RateLimit {
  rooms: string[];
  perSecond: number;
  cooldown: number;
}

interface Rate {
  lastMessage: number;
  messages: number;
}

const rates: {[key: string]: Rate} = {};

@Configurable({
  prefix: {
    '*': '!'
  },
  keywords: ['squeebot'],
  rateLimits: [],
  channelMatching: false,
})
class SqueebotCommandsAPIPlugin extends Plugin {
  private commands: CommandSpec[] = [];
  private permissions: any = null;

  public getRateLimit(room: string): RateLimit | null {
    for (const rm of this.config.get('rateLimits', [])) {
      if (rm.rooms && (rm.rooms.indexOf(room) !== -1 || rm.rooms.indexOf('*') !== -1)) {
        return rm;
      }
    }
    return null;
  }

  public doLimiting(room: string, sender: string): boolean {
    const rl = this.getRateLimit(room);
    if (!rl) {
      return false;
    }

    // Hasn't been limited yet
    if (!rates[sender]) {
      rates[sender] = {
        lastMessage: Date.now(),
        messages: 1,
      };
      return false;
    }

    const r = rates[sender];
    if (r.lastMessage > Date.now() - rl.cooldown) {
      if (r.messages >= rl.perSecond) {
        // Rate limited
        return true;
      }

      r.lastMessage = Date.now();
      r.messages++;
      return false;
    }

    r.lastMessage = Date.now();
    r.messages = 1;
    return false;
  }

  private roomMatcher(msg: IMessage, specList: CommandSpec[]): CommandSpec[] {
    const roomMatches = [];

    for (const spec of specList) {
      if (spec.source) {
        // This message can't room match
        if (!msg.fullRoomID) {
          continue;
        }
        if (typeof spec.source === 'function') {
          try {
            if (spec.source(msg)) {
              roomMatches.push(spec);
            }
          } catch (e) {}
        } else if (typeof spec.source === 'string') {
          if (fullIDMatcher(msg.fullRoomID, spec.source)) {
            roomMatches.push(spec);
          }
        } else if (Array.isArray(spec.source)) {
          for (const room of spec.source) {
            if (fullIDMatcher(msg.fullRoomID, room)) {
              roomMatches.push(spec);
              break;
            }
          }
        }
        continue;
      }

      // No source requirement
      roomMatches.push(spec);
    }

    return roomMatches;
  }

  public permissionMatcher(msg: IMessage, specList: CommandSpec[]): CommandSpec[] {
    const permitted = [];
    for (const spec of specList) {
      if (!spec.permissions) {
        permitted.push(spec);
        continue;
      }

      if (!this.permissions) {
        continue;
      }

      if (!this.permissions.userPermitted(msg, spec.permissions)) {
        continue;
      }

      permitted.push(spec);
    }

    return permitted;
  }

  public async handlePrefix(msg: IMessage, prefix: string, plugins: string[]): Promise<void> {
    const text = msg.text;
    const separate = text.split(' ');
    if (separate[0].indexOf(prefix) === 0) {
      separate[0] = separate[0].substring(prefix.length);
    }

    // Iteration 1: Resolve commands by name and by aliases
    const withAliases = [];
    for (const spec of this.commands) {
      if (plugins.length && plugins.indexOf(spec.plugin) === -1) {
        continue;
      }

      if (spec.aliases && spec.aliases.indexOf(separate[0]) !== -1) {
        const copy = Object.assign({}, spec);
        copy.alias = spec.name;
        withAliases.push(copy);
        continue;
      }

      if (spec.name !== separate[0]) {
        continue;
      }

      withAliases.push(spec);
    }

    // Iteration 2: Match rooms, if needed
    const roomMatches = this.roomMatcher(msg, withAliases);

    // Nothing matches room requirements
    if (!roomMatches.length) {
      return;
    }

    // Iteration 3: Sort the array so that the ones that had room matching come up first
    const sorted = [];
    for (const spec of roomMatches) {
      if (spec.source) {
        sorted.push(spec);
        continue;
      }
      sorted.push(spec);
    }

    // Iteration 4: Match permissions for user
    const permitted = this.permissionMatcher(msg, sorted);

    // Rate limit check
    if (permitted.length &&
        this.config.get('rateLimits', []).length &&
        this.doLimiting(msg.fullRoomID!, msg.fullSenderID!)) {
      logger.warn('[%s] User %s rate limited', this.name, msg.fullSenderID);
      return;
    }

    // Start executing
    for (const spec of permitted) {
      // Help command needs access to plugin list in the channel
      // Very dirty
      if (spec.name === 'help') {
        spec.tempargv = plugins;
      }

      const success = await spec.execute(msg, spec, prefix, ...separate.slice(1));
      if (success) {
        break;
      }
    }

    // Done
  }

  public async handleKeywords(msg: IMessage, keyword: string, plugins: string[]): Promise<void> {
    const text = msg.text.toLowerCase();

    // Only pass command specs which have `match` and match rooms
    let matching = [];
    for (const spec of this.commands) {
      if (!spec.match) {
        continue;
      }

      if (plugins.length && plugins.indexOf(spec.plugin) === -1) {
        continue;
      }

      if (typeof spec.match === 'function') {
        try {
          const match = spec.match(msg);
          if (match == null) {
            continue;
          }
          spec.tempargv = match;
        } catch (e) {}
      } else {
        const rgx = text.match(spec.match);
        if (rgx == null) {
          continue;
        }
        spec.tempargv = rgx.slice(1);
      }

      matching.push(spec);
    }

    matching = this.roomMatcher(msg, matching);

    // Nothing matches room requirements
    if (!matching.length) {
      return;
    }

    // Iteration 2: Sort the array so that the ones that had room matching come up first
    const sorted = [];
    for (const spec of matching) {
      if (spec.source) {
        sorted.push(spec);
        continue;
      }
      sorted.push(spec);
    }

    // Iteration 3: Match permissions for user
    const permitted = this.permissionMatcher(msg, sorted);

    // Rate limit check
    if (permitted.length &&
        this.config.get('rateLimits', []).length &&
        this.doLimiting(msg.fullRoomID!, msg.fullSenderID!)) {
      logger.warn('[%s] User %s rate limited', this.name, msg.fullSenderID);
      return;
    }

    // Start executing
    for (const spec of permitted) {
      const success = await spec.execute(msg, spec, keyword,
        ...(spec.tempargv ? spec.tempargv : []));
      if (success) {
        break;
      }
    }

    // Done
  }

  @EventListener('message')
  public digest(msg: IMessage, chan: IChannel): void {
    if (msg.type !== EMessageType.message) {
      return;
    }

    let allowedPlugins: string[] = [];
    if (chan && this.config.get('channelMatching', false) === true) {
      allowedPlugins = chan.plugins;
    }

    const text = msg.data.text ? msg.data.text : msg.data;
    const prefixes = this.config.config.prefix;
    const keywords = this.config.config.keywords;

    // Attempt to match keywords
    if (keywords && keywords.length) {
      for (const kw of keywords) {
        if (text.toLowerCase().match(kw) != null) {
          this.handleKeywords(msg, kw, allowedPlugins).catch(e =>
            logger.error('[%s] Command handler threw an error:', this.name, e.stack));
          return;
        }
      }
    }

    if (!prefixes) {
      return;
    }

    // Attempt to match prefixes, prefers room-specific ones
    let prefix = '!';
    if (typeof prefixes === 'string') {
      prefix = prefixes;
    } else if (typeof prefixes === 'object') {
      if (msg.fullRoomID) {
        for (const idtag in prefixes) {
          if (idtag === '*') {
            prefix = prefixes[idtag];
            continue;
          }
          if (fullIDMatcher(msg.fullRoomID, idtag)) {
            prefix = prefixes[idtag];
            break;
          }
        }
      }
    }

    if (!prefix || text.indexOf(prefix) !== 0) {
      return;
    }

    this.handlePrefix(msg, prefix, allowedPlugins).catch(e =>
      logger.error('[%s] Command handler threw an error:', this.name, e.stack));
  }

  public registerCommand(spec: CommandSpec | CommandSpec[], bulk = false): boolean {
    if (Array.isArray(spec)) {
      if (!spec.length) {
        return false;
      }

      logger.log('[%s] Plugin %s registered commands %s', this.name,
        spec[0].plugin || 'unknown', spec.map(x => x.name).join(', '));

      let success = true;
      for (const sp of spec) {
        if (!this.registerCommand(sp, true)) {
          success = false;
        }
      }

      return success;
    } else if (!bulk) {
      logger.log('[%s] Plugin %s registered command %s', this.name,
        spec.plugin, spec.name);
    }

    if (!spec.name || !spec.execute || !spec.plugin) {
      throw new Error('Invalid command specification!');
    }

    for (const cmd of this.commands) {
      if (cmd.name === spec.name && cmd.plugin === spec.plugin) {
        return false;
      }
    }

    this.commands.push(spec);

    return true;
  }

  public unregisterPlugin(plugin: string): void {
    const remaining: CommandSpec[] = [];
    const removed: CommandSpec[] = [];

    for (const cmd of this.commands) {
      if (cmd.plugin !== plugin) {
        remaining.push(cmd);
        continue;
      }
      removed.push(cmd);
    }

    if (removed.length) {
      logger.log('[%s] Plugin %s unregistered command(s):', this.name,
        plugin, removed.map(x => x.name).join(', '));
      this.commands = remaining;
    }
  }

  private helpCommand(msg: IMessage, prefix: string, plugins: string[]): void {
    // Iteration 1: Resolve commands by name and by aliases
    const withAliases = [];
    for (const spec of this.commands) {
      if (plugins.length && plugins.indexOf(spec.plugin) === -1) {
        continue;
      }

      if (spec.aliases && spec.aliases.length) {
        for (const alias of spec.aliases) {
          const copy = Object.assign({}, spec);
          copy.name = alias;
          copy.alias = spec.name;
          withAliases.push(copy);
        }
      }

      withAliases.push(spec);
    }

    // Iteration 2: Match rooms for message
    let matching = this.roomMatcher(msg, withAliases);

    // Iteration 3: Match permissions for user
    matching = this.permissionMatcher(msg, matching);

    const text = msg.data.text ? msg.data.text : msg.data;
    const argv = text.toLowerCase().split(' ');
    const b = (t: string) => {
      return msg.source.format.format('bold', t);
    };

    if (argv[1]) {
      let found: CommandSpec | null = null;
      for (const spec of matching) {
        if (spec.name === argv[1]) {
          found = spec;
          break;
        }
      }

      if (!found) {
        msg.resolve('help: No such command "%s"!', argv[1]);
        return;
      }

      let aliasText = '';
      if (found.alias) {
        aliasText = b(`[alias of ${found.alias}]`);
      }

      if (found.usage) {
        msg.resolve('%s %s -', b(prefix + found.name), found.usage,
          found.description || 'No description :(', aliasText);
        return;
      }

      msg.resolve('%s -', b(prefix + found.name), found.description || 'No description :(', aliasText);
      return;
    }

    msg.resolve('All commands start with a "%s" prefix!\n%s', prefix,
      b(`List of commands in ${msg.target?.name}:`),
      matching
        .filter(x => x.alias == null && x.hidden !== true)
        .map(x => x.name).join(', ')
    );
  }

  initialize(): void {
    this.registerCommand({
      plugin: this.name,
      name: 'help',
      aliases: ['commands'],
      usage: '[<command>]',
      description: 'Show command usage or list all commands',
      execute: async (msg: IMessage, spec: CommandSpec, prefix: string): Promise<boolean> => {
        this.helpCommand(msg, prefix, spec.tempargv as string[]);
        return true;
      }
    });
  }

  @DependencyLoad('permissions')
  permissionsAdded(plugin: Plugin): void {
    this.permissions = plugin;
  }

  @DependencyUnload('permissions')
  permissionsRemoved(): void {
    this.permissions = null;
  }

  @EventListener('pluginUnload')
  unloadEventHandler(plugin: string | Plugin): void {
    if (plugin === this.name || plugin === this) {
      logger.debug('[%s] shutting down..', this.name);
      this.config.save().then(() =>
        this.emit('pluginUnloaded', this));
    }
  }

  @EventListener('pluginUnloaded')
  unloadedPlugin(plugin: string | Plugin): void {
    this.unregisterPlugin((typeof plugin === 'string' ? plugin : plugin.manifest.name));
  }
}

module.exports = SqueebotCommandsAPIPlugin;