import { EmbedBuilder, type Client, type Message } from "discord.js";
import type { Payload } from "payload";
import type { Mission, User } from "@/payload-types";
import { botConfig } from "@/bot/config";
import { getMissionAttendance } from "@/lib/attendance";
import { missionTitle } from "@/lib/intelligence/readyReminders";
import { getImminentReminderMissions } from "@/lib/intelligence/imminentReminders";

/**
 * Imminent-op reminder service: 15 minutes before a posted op starts, open a
 * thread on the roll-call message and ping everyone who RSVP'd yes, so the
 * attendees get a last-call nudge that the op is imminent.
 *
 * The pings deliberately ignore `preferences.discord.enabled` (that toggle
 * gates the generic notification DM bridge; a yes RSVP is an explicit intent
 * to attend). One-shot per mission via the imminentReminderSentAt marker,
 * which the cancel flow clears so a rescheduled op re-reminds.
 */

const EMBED_COLOR = 0xf59e0b;
const MISSIONS_PER_TICK = 10;
const THREAD_NAME_MAX = 100;

let reconcileRunning = false;

const errorMessage = (error: unknown): string =>
  error instanceof Error ? error.message : "Unknown error";

const renderReminderEmbed = (mission: Mission): EmbedBuilder => {
  const startUnix = Math.floor(new Date(mission.classification.startDateTime).getTime() / 1000);
  return new EmbedBuilder()
    .setTitle(`⏰ Op starting soon: ${missionTitle(mission)}`)
    .setDescription(`The operation starts <t:${startUnix}:R>. Load up and check in here.`)
    .setColor(EMBED_COLOR)
    .addFields({
      name: "Open the op",
      value: `${botConfig.appUrl}/intelligence/missions/${mission.id}`,
    });
};

const mentionsFor = (users: User[]): string[] =>
  users
    .filter((user) => user.discordId)
    .map((user) => `<@${user.discordId as string}>`);

const fetchRollCallMessage = async (
  client: Client,
  opsChannelId: string,
  messageId: string,
): Promise<Message> => {
  const channel = await client.channels.fetch(opsChannelId);
  if (!channel || !("messages" in channel)) {
    throw new Error(`[Bot] Ops channel ${opsChannelId} is not a text channel.`);
  }
  return channel.messages.fetch(messageId);
};

const processMission = async (
  client: Client,
  payload: Payload,
  mission: Mission,
  now: Date,
): Promise<void> => {
  const opsChannelId = botConfig.opsChannelId;
  if (!opsChannelId || !mission.discordMessageId) return;

  const summary = await getMissionAttendance(payload, mission.id);
  const message = await fetchRollCallMessage(client, opsChannelId, mission.discordMessageId);
  const thread = await message.startThread({
    name: `Op starting soon: ${missionTitle(mission)}`.slice(0, THREAD_NAME_MAX),
    autoArchiveDuration: 60,
  });
  const mentions = mentionsFor(summary.yes);
  await thread.send({
    content: mentions.length > 0 ? mentions.join(" ") : undefined,
    embeds: [renderReminderEmbed(mission)],
  });

  await payload.update({
    collection: "missions",
    id: mission.id,
    data: { imminentReminderSentAt: now.toISOString() },
    overrideAccess: true,
  });
  payload.logger.info(
    `[Bot] Posted imminent-op reminder thread for mission #${mission.id} (${mission.name}); pinged ${mentions.length} attendee(s).`,
  );
};

export interface ReconcileSummary {
  processed: number;
  sent: number;
}

export const reconcile = async (client: Client, payload: Payload): Promise<ReconcileSummary> => {
  if (reconcileRunning) return { processed: 0, sent: 0 };
  if (!botConfig.opsChannelId) return { processed: 0, sent: 0 };
  reconcileRunning = true;
  let processed = 0;
  let sent = 0;
  try {
    const now = new Date();
    const missions = (await getImminentReminderMissions(payload, now)).slice(0, MISSIONS_PER_TICK);
    for (const mission of missions) {
      processed += 1;
      try {
        await processMission(client, payload, mission, now);
        sent += 1;
      } catch (error) {
        payload.logger.error(
          `[Bot] Imminent reminder failed for mission #${mission.id}: ${errorMessage(error)}`,
        );
      }
    }
  } catch (error) {
    payload.logger.error(`[Bot] Imminent reminder reconcile failed: ${errorMessage(error)}`);
  } finally {
    reconcileRunning = false;
  }
  return { processed, sent };
};

export const start = (client: Client, payload: Payload): void => {
  payload.logger.info("[Bot] Imminent reminder service started");
  void reconcile(client, payload);
  setInterval(() => {
    void reconcile(client, payload);
  }, botConfig.imminentReminderPollMs);
};