import { randomUUID } from "node:crypto";
import type { FastifyInstance } from "fastify";
import { eq, permitCredentials, permitPlates, permits, type Db } from "@parking/db";
import { requireRole } from "../auth.js";

// Permit (subscription) admin CRUD. A permit is mutable master data — admins
// grant/edit/revoke — but every USE of it is a signed ledger event, so the audit
// trail stays append-only (see wiki/entities/permit.md). A permit is an aggregate:
// the permit row + its credentials (card/QR) + its bound plates. The API treats them
// as one unit (create/update replace the child sets; delete removes all).

interface Credential {
  kind: "rf" | "qr";
  value: string;
}
interface PermitBody {
  holderName?: string;
  contact?: string;
  /** Car-count binding: cars inside at once. Default 1; null = unbound. */
  maxConcurrent?: number | null;
  validFrom?: string | null;
  validTo?: string | null;
  status?: "active" | "suspended" | "revoked";
  credentials?: Credential[];
  /** Plate binding (optional): bound plates that also serve as identity. */
  plates?: string[];
}

export async function permitRoutes(app: FastifyInstance, db: Db): Promise<void> {
  // Admin manages permits; operator/cashier/readonly may LIST (to look one up).
  const readGuard = requireRole("admin", "operator", "cashier", "readonly");
  const writeGuard = requireRole("admin");

  // Validate the body; returns problems (empty = ok). Shared by create + update.
  function validate(b: PermitBody): string[] {
    const errs: string[] = [];
    if (b.maxConcurrent != null) {
      if (!Number.isInteger(b.maxConcurrent) || b.maxConcurrent < 1) {
        errs.push("maxConcurrent must be a positive integer, or null for unbound");
      }
    }
    if (b.status && !["active", "suspended", "revoked"].includes(b.status)) {
      errs.push("status must be active|suspended|revoked");
    }
    for (const c of b.credentials ?? []) {
      if ((c.kind !== "rf" && c.kind !== "qr") || !c.value?.trim()) {
        errs.push("each credential needs kind (rf|qr) and a non-empty value");
        break;
      }
    }
    if ((b.credentials?.length ?? 0) === 0 && (b.plates?.length ?? 0) === 0) {
      errs.push("a permit needs at least one credential or one bound plate (else nothing identifies it)");
    }
    return errs;
  }

  function loadAggregate(id: string) {
    const permit = db.select().from(permits).where(eq(permits.id, id)).get();
    if (!permit) return null;
    const credentials = db.select().from(permitCredentials).where(eq(permitCredentials.permitId, id)).all();
    const plates = db.select().from(permitPlates).where(eq(permitPlates.permitId, id)).all();
    return {
      ...permit,
      credentials: credentials.map((c) => ({ kind: c.kind, value: c.value })),
      plates: plates.map((p) => p.plate),
    };
  }

  // Replace a permit's child rows (credentials + plates) from the body.
  function writeChildren(id: string, b: PermitBody) {
    db.delete(permitCredentials).where(eq(permitCredentials.permitId, id)).run();
    db.delete(permitPlates).where(eq(permitPlates.permitId, id)).run();
    for (const c of b.credentials ?? []) {
      db.insert(permitCredentials).values({ id: randomUUID(), permitId: id, kind: c.kind, value: c.value.trim() }).run();
    }
    for (const p of b.plates ?? []) {
      if (p.trim()) db.insert(permitPlates).values({ id: randomUUID(), permitId: id, plate: p.trim() }).run();
    }
  }

  // List all permits (with their credentials + plates).
  app.get("/api/permits", { preHandler: readGuard }, async () => {
    const rows = db.select().from(permits).all();
    return { permits: rows.map((r) => loadAggregate(r.id)) };
  });

  // Create a permit.
  app.post<{ Body: PermitBody }>("/api/permits", { preHandler: writeGuard }, async (req, reply) => {
    const b = req.body ?? {};
    const problems = validate(b);
    if (problems.length) return reply.code(400).send({ error: "invalid permit", problems });
    const id = randomUUID();
    db.insert(permits)
      .values({
        id,
        holderName: b.holderName ?? null,
        contact: b.contact ?? null,
        maxConcurrent: b.maxConcurrent === undefined ? 1 : b.maxConcurrent,
        validFrom: b.validFrom ?? null,
        validTo: b.validTo ?? null,
        status: b.status ?? "active",
      })
      .run();
    writeChildren(id, b);
    return reply.code(201).send(loadAggregate(id));
  });

  // Update a permit (replaces fields + child sets).
  app.put<{ Params: { id: string }; Body: PermitBody }>(
    "/api/permits/:id",
    { preHandler: writeGuard },
    async (req, reply) => {
      const existing = db.select().from(permits).where(eq(permits.id, req.params.id)).get();
      if (!existing) return reply.code(404).send({ error: "permit not found" });
      const b = req.body ?? {};
      const problems = validate(b);
      if (problems.length) return reply.code(400).send({ error: "invalid permit", problems });
      db.update(permits)
        .set({
          holderName: b.holderName ?? null,
          contact: b.contact ?? null,
          maxConcurrent: b.maxConcurrent === undefined ? existing.maxConcurrent : b.maxConcurrent,
          validFrom: b.validFrom ?? null,
          validTo: b.validTo ?? null,
          status: b.status ?? existing.status,
        })
        .where(eq(permits.id, req.params.id))
        .run();
      writeChildren(req.params.id, b);
      return loadAggregate(req.params.id);
    },
  );

  // Revoke (soft): the common case — keeps the permit + its history, just bars it.
  // A revoked permit fails the entry check (see permit-flow.ts). Use DELETE only to
  // fully remove a permit created in error.
  app.post<{ Params: { id: string } }>(
    "/api/permits/:id/revoke",
    { preHandler: writeGuard },
    async (req, reply) => {
      const r = db.update(permits).set({ status: "revoked" }).where(eq(permits.id, req.params.id)).run();
      if (r.changes === 0) return reply.code(404).send({ error: "permit not found" });
      return loadAggregate(req.params.id);
    },
  );

  // Hard delete a permit + its child rows. (Past ledger events that reference it
  // are untouched — the audit trail is append-only and independent of this row.)
  app.delete<{ Params: { id: string } }>(
    "/api/permits/:id",
    { preHandler: writeGuard },
    async (req, reply) => {
      const r = db.delete(permits).where(eq(permits.id, req.params.id)).run();
      if (r.changes === 0) return reply.code(404).send({ error: "permit not found" });
      db.delete(permitCredentials).where(eq(permitCredentials.permitId, req.params.id)).run();
      db.delete(permitPlates).where(eq(permitPlates.permitId, req.params.id)).run();
      return reply.code(204).send();
    },
  );
}