import type {ActivityEvent, TimePoint} from '@/features/dashboard/types/dashboard';
import type {Reward, RewardStatus} from '@/features/lyts/types/reward';
import type {RangeKey} from '@/shared/types/api';
import {createRng} from '@/shared/mock/rng';
import {buildTimeseries} from '@/features/dashboard/mock/dashboard.mock';

/**
 * The reward catalogue.
 *
 * `usageRate` is fixed per reward rather than random, because the story this
 * module has to tell is that redemption rates differ WILDLY by offer type —
 * Buy-1-Get-1 is claimed constantly and redeemed rarely, a free coffee is
 * claimed and used almost immediately. A catalogue where everything converts
 * at ~50% would make "most claimed" and "least used" the same reward and the
 * whole module pointless.
 *
 * 1 LYT = ₹1, so costLyt doubles as the rupee liability per redemption.
 */
const CATALOGUE: {
  id: string;
  name: string;
  costLyt: number;
  usageRate: number;
  status: RewardStatus;
  /** Days from now; null never expires. */
  expiresInDays: number | null;
}[] = [
  {id: 'r-coffee', name: 'Free Coffee', costLyt: 120, usageRate: 0.72, status: 'active', expiresInDays: 34},
  {id: 'r-combo20', name: 'Combo 20% off', costLyt: 200, usageRate: 0.34, status: 'expiring', expiresInDays: 2},
  {id: 'r-weekend', name: 'Weekend Bonus', costLyt: 150, usageRate: 0.81, status: 'expiring', expiresInDays: 4},
  {id: 'r-birthday', name: 'Birthday Treat', costLyt: 250, usageRate: 0.55, status: 'active', expiresInDays: null},
  {id: 'r-bogo', name: 'Buy 1 Get 1', costLyt: 400, usageRate: 0.19, status: 'active', expiresInDays: 61},
  {id: 'r-dessert', name: 'Dessert on us', costLyt: 90, usageRate: 0.44, status: 'paused', expiresInDays: 20},
  {id: 'r-firstvisit', name: 'First Visit 10%', costLyt: 100, usageRate: 0.63, status: 'active', expiresInDays: 90},
  {id: 'r-loyalty500', name: 'Loyalty 500', costLyt: 500, usageRate: 0.28, status: 'expired', expiresInDays: -6},
];

export function buildRewards(
  storeId: string,
  range: RangeKey,
  endMs: number,
): Reward[] {
  const scoped = storeId === 'all' ? 1 : 0.28;

  return CATALOGUE.map((r) => {
    const rng = createRng('reward', r.id, storeId, range);
    const claimed = Math.round(rng.int(140, 900) * scoped);
    const used = Math.round(claimed * r.usageRate * rng.float(0.92, 1.08));

    return {
      id: r.id,
      name: r.name,
      costLyt: r.costLyt,
      claimed,
      used: Math.min(used, claimed),
      expiresAt:
        r.expiresInDays === null
          ? null
          : new Date(endMs + r.expiresInDays * 86400000).toISOString(),
      status: r.status,
    };
  });
}

/**
 * Redemptions over time.
 *
 * Derived from the shared timeseries so redemption volume tracks footfall —
 * an independent generator would produce a redemption curve that contradicts
 * the store's own traffic, which is immediately obvious to anyone who knows
 * their business.
 */
export function buildRedemptions(
  storeId: string,
  range: RangeKey,
  endMs: number,
): TimePoint[] {
  const points = buildTimeseries(range, storeId, endMs);
  const rng = createRng('redemptions', storeId, range);

  return points.map((p) => {
    // Roughly a third of purchases involve a redemption.
    const redeemed = Math.round(p.purchases * rng.float(0.24, 0.38));
    const issued = Math.round(redeemed * rng.float(1.5, 2.4));
    return {
      t: p.t,
      // Reusing TimePoint's shape: visitors→issued, purchases→redeemed so the
      // existing chart primitives apply unchanged.
      visitors: issued,
      purchases: redeemed,
      revenue: redeemed * 140,
      conversion: issued ? Number(((redeemed / issued) * 100).toFixed(1)) : 0,
    };
  });
}

const LYT_ACTIVITY: {
  kind: ActivityEvent['kind'];
  title: string;
  detail: string;
}[] = [
  {kind: 'reward_redeemed', title: 'Free Coffee redeemed', detail: '120 LYTs · Indiranagar Flagship'},
  {kind: 'reward_redeemed', title: 'Weekend Bonus redeemed', detail: '150 LYTs · Koramangala'},
  {kind: 'reward_expired', title: 'Loyalty 500 expired', detail: 'Claimed 310 times · used 87'},
  {kind: 'reward_redeemed', title: 'Dessert on us redeemed', detail: '90 LYTs · Anna Nagar'},
  {kind: 'purchase', title: 'Combo 20% applied at checkout', detail: '₹640 basket · Jubilee Hills'},
];

export function buildLytActivity(
  storeId: string,
  endMs: number,
): ActivityEvent[] {
  const rng = createRng('lyt-activity', storeId);
  // Accumulated, not redrawn per index — same ordering bug as buildActivity.
  let minutesAgo = 0;

  return Array.from({length: 24}, (_, i) => {
    const tpl = LYT_ACTIVITY[i % LYT_ACTIVITY.length];
    if (i > 0) minutesAgo += rng.int(8, 50);
    return {
      id: `l${i}`,
      at: new Date(endMs - minutesAgo * 60000).toISOString(),
      kind: tpl.kind,
      title: tpl.title,
      detail: tpl.detail,
      storeId,
    };
  });
}