malice

import type { Person } from './types';

export interface ParsedCommand {

  name: string;

  args: string;

}

export const COMMANDS = [

  'me',

  'msg',

  'join',

  'leave',

  'invite',

  'disinvite',

  'kick',

  'ban',

  'unban',

  'powerlevel',

  'delete',

  'globalnick',

  'globalavatar'

] as const;

export type CommandName = (typeof COMMANDS)[number];

/** A leading `/word`, or null for plain text. `//text` sends `/text` as a message. */

export function parseCommand(text: string): ParsedCommand | null {

  const match = /^\/([a-z]+)(?:\s+([\s\S]*))?$/i.exec(text.trim());

  if (!match) return null;

  return { name: match[1].toLowerCase(), args: (match[2] ?? '').trim() };

}

export function isKnownCommand(name: string): name is CommandName {

  return (COMMANDS as readonly string[]).includes(name);

}

export function unescapeCommand(text: string): string {

  return text.startsWith('//') ? text.slice(1) : text;

}

export type Target = { user_id: string; rest: string } | { error: string };

/** The user an argument string starts with, by matrix id or by a known display name. */

export function splitTarget(args: string, people: Person[]): Target {

  if (!args) return { error: 'Name someone' };

  if (args.startsWith('@')) {

    const [id, ...rest] = args.split(/\s+/);

    if (/^@[^:\s]+:\S+$/.test(id)) return { user_id: id, rest: rest.join(' ') };

  }

  const lower = args.toLowerCase();

  let best: Person[] = [];

  let bestLength = 0;

  for (const person of people) {

    const name = person.name.toLowerCase();

    if (!name || name.length < bestLength) continue;

    if (lower !== name && !lower.startsWith(`${name} `)) continue;

    if (name.length > bestLength) {

      best = [person];

      bestLength = name.length;

    } else {

      best.push(person);

    }

  }

  const ids = [...new Set(best.map((p) => p.user_id))];

  if (ids.length === 0) return { error: `No one here is called ${args.split(/\s+/)[0]}` };

  if (ids.length > 1) return { error: `Several people are called ${best[0].name}, use their @id` };

  return { user_id: ids[0], rest: args.slice(bestLength).trim() };

}