'use strict';

const mdl_TierCategories   = require('../../models/tiers/tier_categories.mdl');
const mdl_TierPlans        = require('../../models/tiers/tier_plans.mdl');
const mdl_PlanPolicies     = require('../../models/tiers/plan_policies.mdl');
const mdl_PaymentPolicies  = require('../../models/tiers/payment_policies.mdl');
const mdl_SystemBadges     = require('../../models/system_badges/system_badges.mdl');
const Asset                = require('../../models/assets/assets.mdl');
const R                    = require('../../utils/response.util');
const logActivity          = require('../../utils/logActivity.util');

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

const VALID_RULE_TYPES = new Set([
  'course_subscription_access',
  'required_active_tier',
  'group_restriction',
  'item_allowlist',
]);

const VALID_ITEM_TYPES = new Set(['course', 'unit', 'lesson']);

async function validateRules(rules) {
  if (!Array.isArray(rules)) return 'access_rules must be an array.';

  // Load valid tier slugs dynamically from DB
  const categories = await mdl_TierCategories.findAll({ attributes: ['slug'] });
  const validSlugs = new Set(categories.map((c) => c.slug));

  for (const rule of rules) {
    if (!VALID_RULE_TYPES.has(rule.type)) return `Unknown rule type: ${rule.type}`;

    if (rule.type === 'course_subscription_access') {
      if (!Array.isArray(rule.levels) || !rule.levels.length)
        return 'course_subscription_access.levels must be a non-empty array of tier slugs.';
    }

    if (rule.type === 'required_active_tier') {
      if (!rule.tier || !validSlugs.has(rule.tier))
        return `required_active_tier.tier must be a valid tier category slug.`;
    }

    if (rule.type === 'group_restriction') {
      if (!Array.isArray(rule.group_ids))
        return 'group_restriction.group_ids must be an array.';
    }

    if (rule.type === 'item_allowlist') {
      if (!VALID_ITEM_TYPES.has(rule.item_type))
        return `item_allowlist.item_type must be one of: ${[...VALID_ITEM_TYPES].join(', ')}.`;
      if (!Array.isArray(rule.item_ids) || !rule.item_ids.length)
        return 'item_allowlist.item_ids must be a non-empty array.';
      if (rule.item_ids.length > 3)
        return 'item_allowlist.item_ids must contain at most 3 items.';
    }
  }
  return null;
}

const ASSET_ATTRS = ['asset_id', 'file_url', 'display_name', 'mime_type'];

// ─── PLAN POLICIES ────────────────────────────────────────────────────────────

exports.getPlanPolicy = async (req, res) => {
  try {
    const plan = await mdl_TierPlans.findByPk(req.params.planId);
    if (!plan) return R.error(res, 'Plan not found.', 404);

    const policy = await mdl_PlanPolicies.findOne({ where: { plan_id: req.params.planId } });
    return R.success(res, 'Policy retrieved.', policy ?? null);
  } catch (err) {
    console.error('[ADMIN][GET PLAN POLICY]', err);
    return R.error(res, 'Could not retrieve policy.', 500);
  }
};

exports.upsertPlanPolicy = async (req, res) => {
  try {
    const { planId } = req.params;

    const plan = await mdl_TierPlans.findByPk(planId);
    if (!plan) return R.error(res, 'Plan not found.', 404);

    const { access_rules } = req.body;

    let parsedRules = [];
    if (access_rules !== undefined) {
      try {
        parsedRules = typeof access_rules === 'string' ? JSON.parse(access_rules) : access_rules;
      } catch {
        return R.error(res, 'access_rules is not valid JSON.', 400);
      }
      const err = await validateRules(parsedRules);
      if (err) return R.error(res, err, 400);
    }

    let existing = await mdl_PlanPolicies.findOne({ where: { plan_id: planId } });

    const payload = {
      plan_id:      planId,
      access_rules: access_rules !== undefined ? parsedRules : (existing?.access_rules ?? []),
    };

    if (!existing) {
      existing = await mdl_PlanPolicies.create(payload);
      logActivity(req.user?.user_id, 'create_plan_policy', { entityType: 'plan_policy', details: { plan_id: planId } });
    } else {
      await existing.update(payload);
      logActivity(req.user?.user_id, 'update_plan_policy', { entityType: 'plan_policy', details: { plan_id: planId } });
    }

    const result = await mdl_PlanPolicies.findOne({ where: { plan_id: planId } });
    return R.success(res, 'Policy saved.', result);
  } catch (err) {
    console.error('[ADMIN][UPSERT PLAN POLICY]', err);
    return R.error(res, 'Could not save policy.', 500);
  }
};

// ─── PAYMENT POLICIES ─────────────────────────────────────────────────────────

const VALID_PROMO_TYPES = new Set(['flat', 'percent']);
const VALID_WINDOW_UNITS = new Set(['minutes', 'hours', 'days']);

function validatePromoRules(rules) {
  if (!Array.isArray(rules)) return 'promo_rules must be an array.';
  for (const r of rules) {
    if (!r.code || typeof r.code !== 'string') return 'Each promo rule must have a code string.';
    if (!VALID_PROMO_TYPES.has(r.type))         return `Invalid promo type "${r.type}". Must be 'flat' or 'percent'.`;
    if (!r.value || Number(r.value) <= 0)       return 'Promo rule value must be a positive number.';
    if (r.max_uses != null && (!Number.isInteger(r.max_uses) || r.max_uses < 1))
      return 'max_uses must be a positive integer.';
    if (r.expires_at != null && isNaN(new Date(r.expires_at).getTime()))
      return 'expires_at must be a valid ISO date string.';
    if (r.min_amount != null && Number(r.min_amount) < 0)
      return 'min_amount must be a non-negative number.';
  }
  return null;
}

function validateRefundPolicy(rp) {
  if (typeof rp !== 'object' || rp === null || Array.isArray(rp))
    return 'refund_policy must be an object.';
  if (rp.allowed != null && typeof rp.allowed !== 'boolean')
    return 'refund_policy.allowed must be a boolean.';
  if (rp.window_unit != null && !VALID_WINDOW_UNITS.has(rp.window_unit))
    return `refund_policy.window_unit must be 'minutes', 'hours', or 'days'.`;
  if (rp.window_value != null && (typeof rp.window_value !== 'number' || rp.window_value <= 0))
    return 'refund_policy.window_value must be a positive number.';
  return null;
}

exports.getPaymentPolicy = async (req, res) => {
  try {
    const plan = await mdl_TierPlans.findByPk(req.params.planId);
    if (!plan) return R.error(res, 'Plan not found.', 404);

    const policy = await mdl_PaymentPolicies.findOne({ where: { plan_id: req.params.planId } });
    return R.success(res, 'Payment policy retrieved.', policy ?? null);
  } catch (err) {
    console.error('[ADMIN][GET PAYMENT POLICY]', err);
    return R.error(res, 'Could not retrieve payment policy.', 500);
  }
};

exports.upsertPaymentPolicy = async (req, res) => {
  try {
    const { planId } = req.params;

    const plan = await mdl_TierPlans.findByPk(planId);
    if (!plan) return R.error(res, 'Plan not found.', 404);

    const { promo_rules, refund_policy, allowed_providers } = req.body;

    if (promo_rules !== undefined) {
      const err = validatePromoRules(promo_rules);
      if (err) return R.error(res, err, 400);
    }

    if (refund_policy !== undefined) {
      const err = validateRefundPolicy(refund_policy);
      if (err) return R.error(res, err, 400);
    }

    if (allowed_providers !== undefined) {
      if (!Array.isArray(allowed_providers) || !allowed_providers.every((p) => typeof p === 'string'))
        return R.error(res, 'allowed_providers must be an array of provider name strings.', 400);
    }

    let existing = await mdl_PaymentPolicies.findOne({ where: { plan_id: planId } });

    const DEFAULTS = { allowed: true, window_value: 5, window_unit: 'minutes', reason_required: false };

    const payload = {
      plan_id:           planId,
      promo_rules:       promo_rules       !== undefined ? promo_rules       : (existing?.promo_rules       ?? []),
      refund_policy:     refund_policy     !== undefined ? refund_policy     : (existing?.refund_policy     ?? DEFAULTS),
      allowed_providers: allowed_providers !== undefined ? allowed_providers : (existing?.allowed_providers ?? ['paypal']),
    };

    if (!existing) {
      existing = await mdl_PaymentPolicies.create(payload);
      logActivity(req.user?.user_id, 'create_payment_policy', { entityType: 'payment_policy', details: { plan_id: planId } });
    } else {
      await existing.update(payload);
      logActivity(req.user?.user_id, 'update_payment_policy', { entityType: 'payment_policy', details: { plan_id: planId } });
    }

    const result = await mdl_PaymentPolicies.findOne({ where: { plan_id: planId } });
    return R.success(res, 'Payment policy saved.', result);
  } catch (err) {
    console.error('[ADMIN][UPSERT PAYMENT POLICY]', err);
    return R.error(res, 'Could not save payment policy.', 500);
  }
};

// ─── SYSTEM BADGES ────────────────────────────────────────────────────────────

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

exports.getSystemBadge = async (req, res) => {
  try {
    const badge = await mdl_SystemBadges.findOne({
      where:   { key: req.params.key },
      include: [{ model: Asset, as: 'asset', attributes: ASSET_ATTRS, required: false }],
    });
    if (!badge) return R.error(res, 'System badge not found.', 404);
    return R.success(res, 'System badge retrieved.', badge);
  } catch (err) {
    console.error('[ADMIN][GET SYSTEM BADGE]', err);
    return R.error(res, 'Could not retrieve system badge.', 500);
  }
};

exports.upsertSystemBadge = async (req, res) => {
  try {
    const { key } = req.params;
    const { asset_id, label, description, information, active_from, active_until } = req.body;

    let existing = await mdl_SystemBadges.findOne({ where: { key } });

    const payload = {
      key,
      asset_id:     asset_id     !== undefined ? (asset_id     || null) : existing?.asset_id     ?? null,
      label:        label        ?? existing?.label        ?? key,
      description:  description  ?? existing?.description  ?? null,
      information:  information  ?? existing?.information  ?? null,
      active_from:  active_from  !== undefined ? (active_from  || null) : existing?.active_from  ?? null,
      active_until: active_until !== undefined ? (active_until || null) : existing?.active_until ?? null,
    };

    if (!existing) {
      existing = await mdl_SystemBadges.create(payload);
      logActivity(req.user?.user_id, 'create_system_badge', { entityType: 'system_badge', details: { key } });
    } else {
      await existing.update(payload);
      logActivity(req.user?.user_id, 'update_system_badge', { entityType: 'system_badge', details: { key } });
    }

    const result = await mdl_SystemBadges.findOne({
      where:   { key },
      include: [{ model: Asset, as: 'asset', attributes: ASSET_ATTRS, required: false }],
    });
    return R.success(res, 'System badge saved.', result);
  } catch (err) {
    console.error('[ADMIN][UPSERT SYSTEM BADGE]', err);
    return R.error(res, 'Could not save system badge.', 500);
  }
};