/***********************************************************************************************************************************************************************
 * File Name: tiers.controller.js  (client)
 * Type of Program: Controller
 * Description: User-facing tier and payment endpoints.
 *              - View active tier + history
 *              - Browse active plans (with courses per plan)
 *              - Promo code validation (server-side)
 *              - PayPal redirect checkout (create order → capture → cancel → refund)
 *              - View own payment history
 * Author: rgrgogu
 * Date Created: Jun. 6, 2026
 * Modified: Jun. 29, 2026
 ***********************************************************************************************************************************************************************/
const mdl_TierCategories = require('../../models/tiers/tier_categories.mdl');
const mdl_TierPlans      = require('../../models/tiers/tier_plans.mdl');
const mdl_UserTiers      = require('../../models/tiers/user_tiers.mdl');
const mdl_Payments       = require('../../models/tiers/payments.mdl');
const mdl_SystemBadges   = require('../../models/system_badges/system_badges.mdl');
const { mdl_UserTierGrants } = require('../../models/tiers/tier.associations');
const Asset              = require('../../models/assets/assets.mdl');
const UserNotification   = require('../../models/notifications/user_notification.mdl');
const { onTierActivated } = require('../../services/achievements.service');
const { Course }         = require('../../models/courses/courses.mdl');
const Unit               = require('../../models/courses/units.mdl');
const Lesson             = require('../../models/courses/lessons.mdl');
const paymentSvc         = require('../../services/payment.service');
const { snapshotPlanGrants } = require('../../services/tierGrants.service');
const R                  = require('../../utils/response.util');
const { NOTIFICATION_REGISTRY } = require('../../data/notifications.data');
const { sendEmail }      = require('../../services/email.service');
const { fmtDate }        = require('../../utils/datetime.util');

require('../../models/tiers/tier.associations');

// ─── MY TIER ──────────────────────────────────────────────────────────────────

// A user can hold more than one active tier concurrently (e.g. premium + exclusive
// bought separately). Returns the full active set plus the highest-rank one as
// `top_tier`, for callers that just want "the best tier this user currently has".
exports.getMyTier = async (req, res) => {
  try {
    const badgeInclude = { model: Asset, as: 'badgeAsset', attributes: ['asset_id', 'storage_provider', 'file_url', 'display_name'], required: false };

    const tiers = await mdl_UserTiers.findAll({
      where: { user_id: req.user.user_id, status: 'active' },
      include: [{
        model:    mdl_TierPlans,
        as:       'plan',
        required: false,
        include:  [{ model: mdl_TierCategories, as: 'category', required: false, include: [badgeInclude] }],
      }],
      order: [['createdAt', 'DESC']],
    });

    // ── Inline safety net: expire between cron ticks ──────────────────────────
    let just_expired = false;
    const stillActive = [];
    for (const tier of tiers) {
      if (tier.expires_at && new Date(tier.expires_at) <= new Date()) {
        await tier.update({ status: 'expired' });
        UserNotification.create({
          user_id: req.user.user_id,
          ...NOTIFICATION_REGISTRY.tier_expired.build({
            tier:   tier.tier,
            label:  tier.plan?.label ?? null,
            planId: tier.plan?.plan_id ?? null,
          }),
        }).catch(() => {});
        just_expired = true;
        continue;
      }
      stillActive.push(tier);
    }

    if (!stillActive.length) {
      const freeCategory = await mdl_TierCategories.findOne({ where: { slug: 'free' }, include: [badgeInclude] });
      const freeTier = { tier: 'free', status: 'active', category: freeCategory ?? null };
      // Spread freeTier at top level too — keeps `myTier.tier`/`myTier.status`/`myTier.category`
      // working for existing frontend code that predates the active_tiers/top_tier shape.
      return R.success(res, 'Active tier retrieved.', {
        ...freeTier,
        active_tiers: [freeTier],
        top_tier:     'free',
        just_expired,
        my_grants: { course_ids: [], unit_ids: [], lesson_ids: [] },
      });
    }

    // Item-specific entitlement (Tier Plans v2) — every course/unit/lesson id
    // granted by ANY of this user's currently-active tiers, flattened, so the
    // client can compute per-plan overlap (see PlanList.jsx) without a
    // separate endpoint per plan.
    const myGrantRows = await mdl_UserTierGrants.findAll({
      where:      { user_tier_id: stillActive.map((t) => t.tier_id) },
      attributes: ['item_type', 'item_id'],
    });
    const my_grants = { course_ids: [], unit_ids: [], lesson_ids: [] };
    for (const g of myGrantRows) {
      if (g.item_type === 'course') my_grants.course_ids.push(g.item_id);
      else if (g.item_type === 'unit') my_grants.unit_ids.push(g.item_id);
      else if (g.item_type === 'lesson') my_grants.lesson_ids.push(g.item_id);
    }

    const categories = await mdl_TierCategories.findAll({ attributes: ['slug', 'rank'] });
    const rankMap = Object.fromEntries(categories.map((c) => [c.slug, c.rank]));

    const active_tiers = [];
    for (const tier of stillActive) {
      if (!tier.plan?.category) {
        const category = await mdl_TierCategories.findOne({ where: { slug: tier.tier }, include: [badgeInclude] });
        const plain = tier.toJSON();
        plain.category = category?.toJSON() ?? null;
        active_tiers.push(plain);
      } else {
        active_tiers.push(tier.toJSON());
      }
    }

    let top_tier = active_tiers[0].tier;
    for (const t of active_tiers) {
      if ((rankMap[t.tier] ?? 0) > (rankMap[top_tier] ?? 0)) top_tier = t.tier;
    }

    const topTierObj = active_tiers.find((t) => t.tier === top_tier) ?? active_tiers[0];

    // Spread topTierObj at top level too — keeps `myTier.tier`/`myTier.status`/
    // `myTier.category`/`myTier.expires_at` working for existing frontend code
    // that predates the active_tiers/top_tier shape (it'll just see the best tier).
    return R.success(res, 'Active tier retrieved.', { ...topTierObj, active_tiers, top_tier, just_expired, my_grants });
  } catch (err) {
    console.error('[CLIENT][GET MY TIER]', err);
    return R.error(res, 'Could not retrieve tier.', 500);
  }
};

exports.getMyTierHistory = async (req, res) => {
  try {
    const history = await mdl_UserTiers.findAll({
      where: { user_id: req.user.user_id },
      order: [['createdAt', 'DESC']],
    });
    return R.success(res, 'Tier history retrieved.', history);
  } catch (err) {
    console.error('[CLIENT][GET MY TIER HISTORY]', err);
    return R.error(res, 'Could not retrieve tier history.', 500);
  }
};

// ─── PLANS ────────────────────────────────────────────────────────────────────

exports.getPlans = async (req, res) => {
  try {
    const plans = await mdl_TierPlans.findAll({
      where:      { status: 'published' },
      order:      [['tier', 'ASC'], ['duration_days', 'ASC']],
      attributes: ['plan_id', 'tier', 'label', 'description', 'features', 'duration_days', 'duration_unit', 'price', 'currency', 'is_active'],
      include:    [
        {
          model:      Course,
          as:         'courses',
          attributes: ['course_id', 'uuid', 'title', 'course_code', 'level', 'duration_seconds'],
          through:    { attributes: [] },
        },
        {
          model:      Unit,
          as:         'units',
          attributes: ['unit_id', 'uuid', 'title', 'duration_seconds'],
          through:    { attributes: [] },
        },
        {
          model:      Lesson,
          as:         'lessons',
          attributes: ['lesson_id', 'uuid', 'title', 'duration_seconds'],
          through:    { attributes: [] },
        },
      ],
    });

    // Each plan holds exactly one bundle type (single-type bundles, Tier Plans
    // v2) — expose the exact item id sets so the client can compute
    // overlap-with-existing-access without extra round-trips (see PlanList.jsx).
    const result = plans.map((p) => {
      const plain = p.toJSON();
      plain.course_count = plain.courses?.length ?? 0;
      plain.unit_count   = plain.units?.length ?? 0;
      plain.lesson_count = plain.lessons?.length ?? 0;
      plain.course_ids   = (plain.courses ?? []).map((c) => c.course_id);
      plain.unit_ids     = (plain.units ?? []).map((u) => u.unit_id);
      plain.lesson_ids   = (plain.lessons ?? []).map((l) => l.lesson_id);
      return plain;
    });

    return R.success(res, 'Plans retrieved.', result);
  } catch (err) {
    console.error('[CLIENT][GET PLANS]', err);
    return R.error(res, 'Could not retrieve plans.', 500);
  }
};

// ─── PROMO CODE VALIDATION ────────────────────────────────────────────────────

exports.validatePromo = async (req, res) => {
  try {
    const { plan_id, code } = req.body;
    if (!plan_id || !code) return R.error(res, 'plan_id and code are required.', 400);

    const plan = await mdl_TierPlans.findOne({ where: { plan_id, is_active: true, status: 'published' } });
    if (!plan) return R.error(res, 'Plan not found or inactive.', 404);

    const policy = await paymentSvc.getPolicyForPlan(plan_id);
    const result = await paymentSvc.evaluatePromo(policy, plan, code, null);

    return R.success(res, result.valid ? 'Promo code is valid.' : result.reason, result);
  } catch (err) {
    console.error('[CLIENT][VALIDATE PROMO]', err);
    return R.error(res, 'Could not validate promo code.', 500);
  }
};

// ─── CHECKOUT ─────────────────────────────────────────────────────────────────

exports.createOrder = async (req, res) => {
  try {
    const { plan_id, promo_code } = req.body;
    if (!plan_id) return R.error(res, 'plan_id is required.', 400);

    const plan = await mdl_TierPlans.findOne({ where: { plan_id, is_active: true, status: 'published' } });
    if (!plan) return R.error(res, 'Plan not found or inactive.', 404);

    // Repurchasing the SAME plan while it's already active is allowed — it
    // extends the existing grant's expires_at (see captureOrder) rather than
    // being blocked. A different plan at the same tier slug is NOT the same
    // purchase — it creates its own independent user_tiers row with its own
    // item-specific grants, so this check is keyed on plan_id, not tier.
    // Surfaced here only for checkout-page messaging.
    const existingActive = await mdl_UserTiers.findOne({
      where: { user_id: req.user.user_id, plan_id, status: 'active' },
      attributes: ['expires_at'],
    });

    const effectivePrice    = Number(plan.price);
    const effectiveCurrency = plan.currency;

    const policy = await paymentSvc.getPolicyForPlan(plan_id);

    let promoResult = { valid: false, code: null, discount: 0 };
    if (promo_code) {
      promoResult = await paymentSvc.evaluatePromo(policy, plan, promo_code, effectivePrice);
      if (!promoResult.valid)
        return R.error(res, promoResult.reason ?? 'Invalid promo code.', 400);
    }

    const subtotal = effectivePrice;
    const discount = promoResult.discount ?? 0;
    const total    = Math.max(subtotal - discount, 0).toFixed(2);

    if (Number(total) <= 0)
      return R.error(res, 'PayPal checkout requires a payable amount.', 400);

    const provider  = (policy?.allowed_providers?.[0]) ?? 'paypal';
    const ppOrder   = await paymentSvc.createOrder(provider, {
      amount:      total,
      currency:    effectiveCurrency,
      referenceId: `user_${req.user.user_id}_plan_${plan_id}`,
    });

    const approvalUrl = ppOrder.links?.find((l) => l.rel === 'approve')?.href ?? null;

    const payment = await mdl_Payments.create({
      user_id:          req.user.user_id,
      plan_id,
      status:           'pending',
      amount:           total,
      currency:         effectiveCurrency,
      promo_code:       promoResult.code,
      discount:         discount.toFixed(2),
      provider,
      provider_payload: {
        order_id:     ppOrder.id,
        approval_url: approvalUrl,
        checkout: {
          subtotal:      subtotal.toFixed(2),
          discount:      discount.toFixed(2),
          promo_code:    promoResult.code,
          base_price:    Number(plan.price).toFixed(2),
          base_currency: plan.currency,
        },
      },
    });

    return R.success(res, 'Order created.', {
      payment_id:        payment.payment_id,
      order_id:          ppOrder.id,
      approval_url:      approvalUrl,
      amount:            total,
      currency:          effectiveCurrency,
      promo_code:        promoResult.code,
      discount:          discount.toFixed(2),
      extends_existing:  !!existingActive,
      current_expires_at: existingActive?.expires_at ?? null,
    }, 201);
  } catch (err) {
    console.error('[CLIENT][CREATE ORDER]', err);
    return R.error(res, 'Could not create order.', 500);
  }
};

exports.captureOrder = async (req, res) => {
  try {
    const { order_id } = req.body;
    if (!order_id) return R.error(res, 'order_id is required.', 400);

    const payment = await mdl_Payments.findOne({
      where:   { status: 'pending', user_id: req.user.user_id },
      include: [{ model: mdl_TierPlans, as: 'plan' }],
      order:   [['createdAt', 'DESC']],
    });

    if (!payment || payment.provider_payload?.order_id !== order_id)
      return R.error(res, 'Pending payment not found.', 404);

    // Guard: plan was deactivated while user was on PayPal's approval page
    if (!payment.plan?.is_active) {
      await payment.update({
        status:           'cancelled',
        provider_payload: {
          ...payment.provider_payload,
          cancelled_at:    new Date().toISOString(),
          cancelled_by:    'system',
          cancel_reason:   'plan_deactivated',
        },
      });
      return R.error(res, 'This plan is no longer available. No payment was taken.', 409);
    }

    let captureData;
    try {
      captureData = await paymentSvc.captureOrder(payment.provider, order_id);
    } catch (ppErr) {
      await payment.update({
        status:           'failed',
        provider_payload: { ...payment.provider_payload, error: ppErr?.response?.data ?? {} },
      });
      return R.error(res, 'Payment capture failed.', 402);
    }

    const capture = captureData.purchase_units?.[0]?.payments?.captures?.[0];

    // PayPal can return an HTTP 2xx from the capture endpoint even when the
    // charge itself was declined or held for review (e.g. capture.status
    // "DECLINED"/"PENDING") — axios only throws on non-2xx, so the actual
    // status field must be checked explicitly before granting any access.
    const captureStatus = capture?.status ?? captureData.status;
    if (captureStatus !== 'COMPLETED') {
      await payment.update({
        status:           'failed',
        provider_payload: { ...payment.provider_payload, capture: captureData, failed_reason: captureStatus ?? 'unknown' },
      });
      return R.error(res, `Payment was not completed by PayPal (status: ${captureStatus ?? 'unknown'}).`, 402);
    }

    // Repurchasing THIS SAME plan while already active extends its expires_at
    // by the new duration, rather than being blocked/refunded. A different
    // plan — even at the same tier slug — is a distinct purchase and gets its
    // own user_tiers row with its own item-specific grants (see
    // snapshotPlanGrants below); it must NOT be merged into an unrelated
    // plan's row just because the tier slug matches (Tier Plans v2 — a Unit
    // bundle and a Course bundle can both be "premium" and both need to stay
    // independently active/tracked).
    const existingActive = await mdl_UserTiers.findOne({
      where: { user_id: req.user.user_id, plan_id: payment.plan_id, status: 'active' },
    });

    let resultTier;
    let successMessage;

    if (existingActive) {
      const newExpiresAt = new Date(existingActive.expires_at.getTime() + payment.plan.duration_days * 86400000);
      await existingActive.update({ expires_at: newExpiresAt });
      resultTier = existingActive;
      successMessage = `Payment successful. Your ${payment.plan.tier} access has been extended to ${newExpiresAt.toLocaleDateString()}.`;
    } else {
      const startsAt  = new Date();
      const expiresAt = new Date(startsAt.getTime() + payment.plan.duration_days * 86400000);

      resultTier = await mdl_UserTiers.create({
        user_id:   req.user.user_id,
        tier:      payment.plan.tier,
        plan_id:   payment.plan_id,
        status:    'active',
        starts_at: startsAt,
        expires_at: expiresAt,
        granted_by: null,
      });
      successMessage = 'Payment successful. Tier activated.';
    }

    // Snapshot the plan's current bundle contents into user_tier_grants —
    // refreshed on every purchase/extension so an admin's bundle edits since
    // the last purchase are picked up, but past purchasers of OTHER plans are
    // never retroactively affected (Tier Plans v2 item-specific entitlement).
    await snapshotPlanGrants(resultTier, payment.plan_id);

    await payment.update({
      status:           'completed',
      tier_id:          resultTier.tier_id,
      paid_at:          new Date(),
      provider_payload: {
        ...payment.provider_payload,
        capture_id: capture?.id,
        payer_id:   captureData.payer?.payer_id,
        capture:    captureData,
      },
    });

    // Idempotent (grantAchievement checks for an existing row first) — safe
    // to call again on an extension, won't grant a duplicate achievement.
    await onTierActivated(req.user.user_id, resultTier.tier);

    return R.success(res, successMessage, {
      tier:       resultTier.tier,
      expires_at: resultTier.expires_at,
      extended:   !!existingActive,
    });
  } catch (err) {
    console.error('[CLIENT][CAPTURE ORDER]', err);
    return R.error(res, 'Could not capture order.', 500);
  }
};

exports.cancelOrder = async (req, res) => {
  try {
    const { order_id } = req.body;
    if (!order_id) return R.error(res, 'order_id is required.', 400);

    const payment = await mdl_Payments.findOne({
      where: { user_id: req.user.user_id, status: 'pending' },
      order: [['createdAt', 'DESC']],
    });

    if (!payment || payment.provider_payload?.order_id !== order_id)
      return R.error(res, 'Pending payment not found.', 404);

    await payment.update({
      status:           'cancelled',
      provider_payload: {
        ...payment.provider_payload,
        cancelled_at: new Date().toISOString(),
        cancelled_by: 'payer',
      },
    });

    return R.success(res, 'Payment cancelled.');
  } catch (err) {
    console.error('[CLIENT][CANCEL ORDER]', err);
    return R.error(res, 'Could not cancel payment.', 500);
  }
};

exports.refundOrder = async (req, res) => {
  try {
    const user_id = req.user.user_id;
    // plan_id disambiguates which active subscription to refund now that a user
    // can hold more than one concurrently — optional only while a user has just one.
    const { plan_id } = req.body;

    const activeTierWhere = { user_id, status: 'active' };
    if (plan_id) activeTierWhere.plan_id = plan_id;

    const activeTierCandidates = await mdl_UserTiers.findAll({
      where: activeTierWhere,
      order: [['createdAt', 'DESC']],
    });
    if (!activeTierCandidates.length) return R.error(res, 'No active tier to refund.', 404);
    if (activeTierCandidates.length > 1) {
      return R.error(res, 'You have more than one active subscription — specify plan_id to refund a specific one.', 400);
    }
    const activeTier = activeTierCandidates[0];

    const payment = await mdl_Payments.findOne({
      where: { user_id, tier_id: activeTier.tier_id, status: 'completed' },
      order: [['paid_at', 'DESC']],
    });
    if (!payment) return R.error(res, 'No completed payment found for this tier.', 404);

    // Load plan's payment policy to get the configured refund window
    const policy = await paymentSvc.getPolicyForPlan(payment.plan_id);

    if (!paymentSvc.isRefundAllowed(policy))
      return R.error(res, 'Refunds are not available for this plan.', 403);

    const windowMs = paymentSvc.getRefundWindowMs(policy);
    if (!payment.paid_at || Date.now() - new Date(payment.paid_at).getTime() > windowMs) {
      const rp = policy?.refund_policy ?? {};
      const label = `${rp.window_value ?? 5} ${rp.window_unit ?? 'minutes'}`;
      return R.error(res, `Refund window has expired. Refunds are only available within ${label} of payment.`, 403);
    }

    const captureId = payment.provider_payload?.capture_id;
    if (!captureId) return R.error(res, 'Capture ID not found. Cannot process refund.', 400);

    let refundData;
    try {
      refundData = await paymentSvc.refundCapture(payment.provider, captureId, payment.amount, payment.currency);
    } catch (ppErr) {
      console.error('[CLIENT][REFUND] provider error:', ppErr?.response?.data);
      return R.error(res, 'Refund failed. Please try again.', 402);
    }

    await payment.update({
      status:           'refunded',
      provider_payload: {
        ...payment.provider_payload,
        refund:      refundData,
        refunded_at: new Date().toISOString(),
      },
    });

    const now = new Date();
    await activeTier.update({ status: 'revoked', expires_at: now, revoked_at: now });

    const plan = await mdl_TierPlans.findByPk(payment.plan_id, { attributes: ['plan_id', 'label'] });

    try {
      const notify = NOTIFICATION_REGISTRY.payment_refunded.build({
        label:    plan?.label ?? 'your plan',
        amount:   payment.amount,
        currency: payment.currency,
        planId:   plan?.plan_id ?? null,
      });
      await UserNotification.create({ user_id, ...notify, seen: false });
    } catch (notifyErr) {
      console.error('[CLIENT][REFUND][NOTIFY]', notifyErr);
    }

    try {
      const name = req.user.personal_info?.name?.full_name ?? 'there';
      sendEmail({
        to:   req.user.email,
        type: 'REFUND_PROCESSED',
        data: {
          name,
          label:    plan?.label ?? 'your plan',
          amount:   payment.amount,
          currency: payment.currency,
          date:     fmtDate(now),
          refundId: refundData.id,
        },
      }).catch((emailErr) => console.error('[CLIENT][REFUND][EMAIL]', emailErr));
    } catch (emailErr) {
      console.error('[CLIENT][REFUND][EMAIL]', emailErr);
    }

    // Only fall back to free if the user has no other concurrently active tier —
    // revoking one subscription shouldn't drop them below a tier they still hold.
    const remainingActive = await mdl_UserTiers.count({ where: { user_id, status: 'active' } });
    if (remainingActive > 0) {
      return R.success(res, 'Refund processed successfully. Your access to this plan has been revoked.', {
        refund_id: refundData.id,
        status:    refundData.status,
      });
    }

    await mdl_UserTiers.create({
      user_id,
      tier:       'free',
      status:     'active',
      starts_at:  now,
      expires_at: null,
      granted_by: null,
      notes:      'Auto-downgrade after refund.',
    });

    return R.success(res, 'Refund processed successfully. Your access has been revoked.', {
      refund_id: refundData.id,
      status:    refundData.status,
    });
  } catch (err) {
    console.error('[CLIENT][REFUND]', err);
    return R.error(res, 'Could not process refund.', 500);
  }
};

// ─── MY PAYMENTS ──────────────────────────────────────────────────────────────

exports.getMyPayments = async (req, res) => {
  try {
    const payments = await mdl_Payments.findAll({
      where:      { user_id: req.user.user_id },
      include:    [{ model: mdl_TierPlans, as: 'plan', attributes: ['label', 'tier', 'duration_days'] }],
      attributes: { exclude: ['provider_payload'] },
      order:      [['createdAt', 'DESC']],
    });
    return R.success(res, 'Payment history retrieved.', payments);
  } catch (err) {
    console.error('[CLIENT][GET MY PAYMENTS]', err);
    return R.error(res, 'Could not retrieve payment history.', 500);
  }
};

// ─── TIER CATEGORIES + SYSTEM BADGES ─────────────────────────────────────────

exports.getCategories = async (req, res) => {
  try {
    const categories = await mdl_TierCategories.findAll({
      where:      { is_active: true },
      attributes: ['tier_category_id', 'slug', 'name', 'rank', 'color', 'badge_icon', 'badge_label', 'is_default'],
      include:    [{ model: Asset, as: 'badgeAsset', attributes: ['asset_id', 'storage_provider', 'file_url', 'display_name'], required: false }],
      order:      [['rank', 'ASC']],
    });
    return R.success(res, 'Tier categories retrieved.', categories);
  } catch (err) {
    console.error('[CLIENT][GET TIER CATEGORIES]', err);
    return R.error(res, 'Could not retrieve tier categories.', 500);
  }
};

exports.getSystemBadges = async (req, res) => {
  try {
    const badges = await mdl_SystemBadges.findAll({
      attributes: ['key', 'label', 'description', 'information', 'active_from', 'active_until'],
      include:    [{ model: Asset, as: 'asset', attributes: ['file_url', 'display_name'], required: false }],
      order:      [['key', 'ASC']],
    });
    return R.success(res, 'System badges retrieved.', badges);
  } catch (err) {
    console.error('[CLIENT][GET SYSTEM BADGES]', err);
    return R.error(res, 'Could not retrieve system badges.', 500);
  }
};