require('dotenv').config({ path: require('path').join(__dirname, '../../.env') });
const mongoose = require('mongoose');
const { connectDB } = require('../config/database');
const WhatsAppQueue = require('../models/WhatsAppQueue');
const MessagingCampaign = require('../models/MessagingCampaign');
const Event = require('../models/Event');
const WhatsAppTemplate = require('../models/WhatsAppTemplate');
const Participant = require('../models/Participant');
const {
  getOrgWhatsAppCredentials,
  sendTemplateMessage,
  parseWhatsAppCloudMessagesSendResponse,
} = require('../utils/metaWhatsApp');
const { buildWhatsAppTemplatePayload } = require('../utils/waTemplateSendParams');
const { getCampaignContentObject } = require('../utils/campaignContent');
const { flattenParticipantForEvent } = require('../utils/participantMembership');

const POLL_MS = Math.max(500, parseInt(process.env.WHATSAPP_WORKER_POLL_MS || '2000', 10));
const MAX_ATTEMPTS = Math.max(1, parseInt(process.env.WHATSAPP_WORKER_MAX_ATTEMPTS || '3', 10));
const MIN_INTERVAL_MS = Math.max(0, parseInt(process.env.WHATSAPP_WORKER_MIN_INTERVAL_MS || '400', 10));
let lastSendAt = 0;

function sleep(ms) {
  return new Promise((r) => setTimeout(r, ms));
}

async function throttle() {
  if (MIN_INTERVAL_MS <= 0) return;
  const now = Date.now();
  const wait = lastSendAt + MIN_INTERVAL_MS - now;
  if (wait > 0) await sleep(wait);
  lastSendAt = Date.now();
}

async function finalizeCampaignIfDone(campaignId) {
  const pending = await WhatsAppQueue.countDocuments({ campaign: campaignId, status: { $in: ['pending', 'processing'] } });
  if (pending > 0) return;
  const camp = await MessagingCampaign.findById(campaignId);
  if (!camp || camp.status === 'stopped') return;
  const failed = await WhatsAppQueue.countDocuments({ campaign: campaignId, status: 'failed' });
  const sent = await WhatsAppQueue.countDocuments({ campaign: campaignId, status: 'sent' });
  if (sent === 0 && failed > 0) {
    camp.status = 'failed';
  } else {
    camp.status = 'sent';
  }
  camp.sentAt = new Date();
  await camp.save();
}

async function processOne() {
  const now = new Date();
  const job = await WhatsAppQueue.findOneAndUpdate(
    {
      status: 'pending',
      processAfter: { $lte: now },
    },
    {
      $set: { status: 'processing', lockedAt: now },
      $inc: { attempts: 1 },
    },
    { sort: { createdAt: 1 }, new: true }
  );

  if (!job) return false;

  const campaign = await MessagingCampaign.findById(job.campaign);
  if (!campaign) {
    job.status = 'cancelled';
    await job.save();
    return true;
  }

  if (campaign.status === 'stopped') {
    job.status = 'cancelled';
    await job.save();
    return true;
  }

  if (campaign.status === 'scheduled') {
    campaign.status = 'sending';
    await campaign.save();
  }

  const orgId = job.organization?._id || job.organization;
  const creds = orgId && (await getOrgWhatsAppCredentials(String(orgId)));
  if (!creds || !creds.accessToken) {
    job.status = 'failed';
    job.lastError = 'WhatsApp not configured (token)';
    await job.save();
    await finalizeFailed(campaign, job);
    await finalizeCampaignIfDone(campaign._id);
    return true;
  }
  if (!creds.phoneNumberId) {
    job.status = 'failed';
    job.lastError = 'WhatsApp phone number ID missing (set in Settings)';
    await job.save();
    await finalizeFailed(campaign, job);
    await finalizeCampaignIfDone(campaign._id);
    return true;
  }

  const eventDoc = await Event.findById(campaign.event).lean();
  const tplId = getCampaignContentObject(campaign).whatsappTemplateId;
  const tpl = tplId && mongoose.Types.ObjectId.isValid(String(tplId)) ? await WhatsAppTemplate.findById(tplId).lean() : null;
  if (!eventDoc || !tpl) {
    job.status = 'failed';
    job.lastError = 'Template or event missing';
    await job.save();
    await finalizeFailed(campaign, job);
    await finalizeCampaignIfDone(campaign._id);
    return true;
  }

  const p = job.participant ? await Participant.findById(job.participant).lean() : null;
  if (!p) {
    job.status = 'failed';
    job.lastError = 'Participant not found';
    await job.save();
    await finalizeFailed(campaign, job);
    await finalizeCampaignIfDone(campaign._id);
    return true;
  }
  const flat = flattenParticipantForEvent(p, campaign.event);
  if (!flat) {
    job.status = 'failed';
    job.lastError = 'Participant not in event';
    await job.save();
    await finalizeFailed(campaign, job);
    await finalizeCampaignIfDone(campaign._id);
    return true;
  }

  let built;
  try {
    const content = getCampaignContentObject(campaign);
    built = buildWhatsAppTemplatePayload(tpl, content, flat, eventDoc);
  } catch (e) {
    job.status = 'failed';
    job.lastError = e.message || 'build template failed';
    await job.save();
    await finalizeFailed(campaign, job);
    await finalizeCampaignIfDone(campaign._id);
    return true;
  }

  try {
    await throttle();
    const sendBody = await sendTemplateMessage(creds.phoneNumberId, creds.accessToken, job.to, built.template);
    const { whatsappMessageId, recipientWaId } = parseWhatsAppCloudMessagesSendResponse(sendBody);
    if (whatsappMessageId) job.whatsappMessageId = whatsappMessageId;
    if (recipientWaId) job.recipientWaId = recipientWaId;
  } catch (e) {
    const msg = e.message || 'Meta send failed';
    if (job.attempts >= MAX_ATTEMPTS) {
      job.status = 'failed';
      job.lastError = msg;
    } else {
      job.status = 'pending';
      job.lastError = msg;
      job.processAfter = new Date(Date.now() + 60_000 * job.attempts);
    }
    await job.save();
    if (job.status === 'failed') await finalizeFailed(campaign, job);
    await finalizeCampaignIfDone(campaign._id);
    return true;
  }

  job.status = 'sent';
  job.sentAt = new Date();
  job.lastError = undefined;
  await job.save();
  campaign.stats = campaign.stats || {};
  campaign.stats.sent = (campaign.stats.sent || 0) + 1;
  await campaign.save();
  await finalizeCampaignIfDone(campaign._id);
  return true;
}

async function finalizeFailed(campaign, job) {
  if (job.status !== 'failed') return;
  campaign.stats = campaign.stats || {};
  campaign.stats.failed = (campaign.stats.failed || 0) + 1;
  await campaign.save();
}

async function run() {
  await connectDB();
  console.log(
    '[whatsappQueueWorker] started, poll',
    POLL_MS,
    'ms, min interval',
    MIN_INTERVAL_MS,
    'ms',
  );
  for (;;) {
    try {
      const did = await processOne();
      if (!did) await sleep(POLL_MS);
    } catch (e) {
      console.error('[whatsappQueueWorker]', e);
      await sleep(POLL_MS);
    }
  }
}

if (require.main === module) {
  run();
}

module.exports = { processOne, run };