const DEFAULT_TAGLINE = "All your chats, one ClawdBot.";

const TAGLINES: string[] = [];

type HolidayRule = (date: Date) => boolean;

const HOLIDAY_RULES = new Map<string, HolidayRule>();

function isTaglineActive(tagline: string, date: Date): boolean {
  const rule = HOLIDAY_RULES.get(tagline);
  if (!rule) return true;
  return rule(date);
}

export interface TaglineOptions {
  env?: NodeJS.ProcessEnv;
  random?: () => number;
  now?: () => Date;
}

export function activeTaglines(options: TaglineOptions = {}): string[] {
  if (TAGLINES.length === 0) return [DEFAULT_TAGLINE];
  const today = options.now ? options.now() : new Date();
  const filtered = TAGLINES.filter((tagline) =>
    isTaglineActive(tagline, today),
  );
  return filtered.length > 0 ? filtered : TAGLINES;
}

export function pickTagline(options: TaglineOptions = {}): string {
  const env = options.env ?? process.env;
  const override = env?.CLAWDBOT_TAGLINE_INDEX;
  if (override !== undefined) {
    const parsed = Number.parseInt(override, 10);
    if (!Number.isNaN(parsed) && parsed >= 0) {
      const pool = TAGLINES.length > 0 ? TAGLINES : [DEFAULT_TAGLINE];
      return pool[parsed % pool.length];
    }
  }
  const pool = activeTaglines(options);
  const rand = options.random ?? Math.random;
  const index = Math.floor(rand() * pool.length) % pool.length;
  return pool[index];
}

export { TAGLINES, HOLIDAY_RULES, DEFAULT_TAGLINE };