import { randomUUID } from "node:crypto";
import type { FastifyInstance } from "fastify";
import { desc, eq, subscriptionPlans, type Db } from "@parking/db";
import { SUBSCRIPTION_PERIODS, type PlanTimeframes, type SubscriptionPeriod } from "@parking/shared";
import { requirePermission } from "../auth.js";
import { siteTz } from "../subscription-window.js";

// Subscription PLAN catalog — admin-composed, versioned config the operator SELLS
// from (so they never type a price). Mirrors the tariff composer: plans are
// EFFECTIVE-DATED IMMUTABLE VERSIONS keyed by a stable `planId`; editing a plan
// PUBLISHES A NEW VERSION (new row, new effectiveFrom), never mutates an old one, so
// a past sale reprices identically against its recorded planVersionId. Retire =
// active=0 (soft, keeps history). Admin-only (`subscription:plan`); selling stays
// operator-grade (`subscription:create`). See wiki/entities/subscription.md.

interface PlanBody {
  /** Stable identity across versions (e.g. "hotel-daily"). New on create; reused to
   *  publish a new version of an existing plan. Slugified server-side. */
  planId?: string;
  name?: string;
  period?: SubscriptionPeriod;
  pricePerPeriodMinor?: number;
  currency?: string;
  /** When this version takes effect (ISO-8601). Defaults to now. */
  effectiveFrom?: string;
  /** Allowed-time windows (tariff bridge); null/omitted = 24/7. */
  timeframes?: PlanTimeframes | null;
}

/** Validate the optional timeframes blob (minutes-of-day 0–1439, sane grace). */
function validTimeframes(tf: PlanTimeframes | null | undefined): string | null {
  if (tf == null) return null;
  const okMin = (v: unknown) => v == null || (Number.isInteger(v) && (v as number) >= 0 && (v as number) <= 1439);
  for (const dt of [tf.weekday, tf.weekend]) {
    if (!dt) continue;
    if (!dt.allDay && (!okMin(dt.fromMin) || !okMin(dt.toMin))) return "window times must be minutes-of-day (0–1439)";
  }
  if (tf.graceMin != null && (!Number.isInteger(tf.graceMin) || tf.graceMin < 0)) return "graceMin must be ≥ 0";
  return null;
}

/** Lowercase, hyphenate, strip junk — a stable slug for the plan identity. */
function slugify(s: string): string {
  return s
    .trim()
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, "-")
    .replace(/^-+|-+$/g, "")
    .slice(0, 48);
}

export async function subscriptionPlanRoutes(app: FastifyInstance, db: Db): Promise<void> {
  const readGuard = requirePermission("subscription:read");
  const planGuard = requirePermission("subscription:plan");

  function validate(b: PlanBody): string[] {
    const errs: string[] = [];
    if (!b.name?.trim()) errs.push("name is required");
    if (!b.period || !SUBSCRIPTION_PERIODS.includes(b.period)) {
      errs.push(`period must be one of: ${SUBSCRIPTION_PERIODS.join(", ")}`);
    }
    if (!Number.isInteger(b.pricePerPeriodMinor) || (b.pricePerPeriodMinor ?? 0) <= 0) {
      errs.push("pricePerPeriodMinor must be a positive integer (minor units)");
    }
    if (!b.currency?.trim()) errs.push("currency is required");
    if (b.effectiveFrom != null && Number.isNaN(Date.parse(b.effectiveFrom))) {
      errs.push("effectiveFrom must be a valid ISO-8601 timestamp");
    }
    const tfErr = validTimeframes(b.timeframes);
    if (tfErr) errs.push(tfErr);
    return errs;
  }

  // List plans. ?all=1 → every version (history); default → the CURRENT sellable plan
  // per planId (latest active version with effectiveFrom ≤ now). Operators selling
  // need the current list; the admin catalog screen asks for ?all=1.
  app.get<{ Querystring: { all?: string } }>("/api/subscription-plans", { preHandler: readGuard }, async (req) => {
    const rows = db.select().from(subscriptionPlans).orderBy(desc(subscriptionPlans.effectiveFrom)).all();
    if (req.query?.all) return { plans: rows };
    const now = new Date().toISOString();
    // Newest-effective active version wins per planId.
    const current = new Map<string, (typeof rows)[number]>();
    for (const r of rows) {
      if (!r.active || r.effectiveFrom > now) continue;
      if (!current.has(r.planId)) current.set(r.planId, r); // rows are newest-first
    }
    return { plans: [...current.values()] };
  });

  // Publish a plan version (create a plan, or a new version of an existing planId).
  app.post<{ Body: PlanBody }>("/api/subscription-plans", { preHandler: planGuard }, async (req, reply) => {
    const b = req.body ?? ({} as PlanBody);
    const problems = validate(b);
    if (problems.length) return reply.code(400).send({ error: "invalid plan", problems });

    const planId = (b.planId?.trim() ? slugify(b.planId) : slugify(b.name!)) || randomUUID();
    const now = new Date().toISOString();
    const effectiveFrom = b.effectiveFrom?.trim() || now;
    // Backdating would retroactively reprice — refuse (mirrors tariff publish).
    if (Date.parse(effectiveFrom) < Date.parse(now) - 60_000) {
      return reply.code(400).send({
        error: "effectiveFrom cannot be in the past — backdating a plan would retroactively reprice sales",
      });
    }
    // Stamp the site tz into the timeframes so the windows evaluate in the site's
    // wall-clock, FROZEN in this version (mirrors how tariff V2 freezes its tz).
    const timeframes =
      b.timeframes != null ? { ...b.timeframes, tz: b.timeframes.tz || siteTz(db) } : null;

    const row = {
      id: randomUUID(),
      planId,
      name: b.name!.trim(),
      period: b.period!,
      pricePerPeriodMinor: b.pricePerPeriodMinor!,
      currency: b.currency!.trim(),
      effectiveFrom,
      timeframes,
      active: true,
      createdBy: req.user?.username ?? null,
    };
    db.insert(subscriptionPlans).values(row as typeof subscriptionPlans.$inferInsert).run();
    return reply.code(201).send(row);
  });

  // Retire a plan (soft): mark every version of this planId inactive so it's no longer
  // sellable. History (and past sales' planVersionId) is preserved. Re-publish to revive.
  app.post<{ Params: { planId: string } }>(
    "/api/subscription-plans/:planId/retire",
    { preHandler: planGuard },
    async (req) => {
      db.update(subscriptionPlans)
        .set({ active: false })
        .where(eq(subscriptionPlans.planId, req.params.planId))
        .run();
      return { planId: req.params.planId, retired: true };
    },
  );
}