import { afterEach, beforeEach, describe, expect, it } from "vitest";
import { createTestDb } from "@parking/db/testing";
import { ledgerEvents, siteConfig, subscriptions, type Db } from "@parking/db";
import { getOccupancy, occupancyCount, reservedSubscriberSpots } from "./occupancy.js";

// Occupancy is a FOLD over the signed ledger, never a stored counter. These tests
// pin: the entries-minus-exits count, the capacity/full gate, and the reserved-
// subscriber-spots model (its trickiest invariant — never double-count a parked
// subscriber, and never gate the subscriber's own entry).

let db: Db;
let close: () => void;

beforeEach(() => {
  const t = createTestDb();
  db = t.db;
  close = t.close;
});
afterEach(() => close());

// Insert a ledger row directly (these fns read raw rows; signing is event-log's job).
let idx = 0;
function entry(identity: string, payload?: Record<string, unknown>) {
  idx += 1;
  db.insert(ledgerEvents).values({
    id: `e${idx}`, index: idx, type: "vehicle_entry", direction: "entry",
    identity, payload: payload ?? null, occurredAt: new Date().toISOString(),
    signature: "x", keyId: "test",
  }).run();
}
function exit(identity: string) {
  idx += 1;
  db.insert(ledgerEvents).values({
    id: `e${idx}`, index: idx, type: "vehicle_exit", direction: "exit",
    identity, payload: null, occurredAt: new Date().toISOString(),
    signature: "x", keyId: "test",
  }).run();
}
function voidEvt(identity: string) {
  idx += 1;
  db.insert(ledgerEvents).values({
    id: `e${idx}`, index: idx, type: "void",
    identity, payload: { sessionRef: identity, voidReason: "misprint" }, occurredAt: new Date().toISOString(),
    signature: "x", keyId: "test",
  }).run();
}
function setSite(v: Partial<typeof siteConfig.$inferInsert>) {
  db.insert(siteConfig).values({ id: 1, ...v }).onConflictDoUpdate({ target: siteConfig.id, set: v }).run();
}

describe("occupancyCount", () => {
  beforeEach(() => { idx = 0; });

  it("is 0 with no events", () => {
    expect(occupancyCount(db)).toBe(0);
  });

  it("counts open sessions (entries minus matching exits)", () => {
    entry("A"); entry("B"); entry("C");
    exit("B");
    expect(occupancyCount(db)).toBe(2);
  });

  it("a re-entry after exit counts again", () => {
    entry("A"); exit("A"); entry("A");
    expect(occupancyCount(db)).toBe(1);
  });

  it("a voided (cancelled) entry does NOT count inside", () => {
    entry("A"); entry("B");
    voidEvt("B"); // B's ticket was a misprint — cancelled
    expect(occupancyCount(db)).toBe(1);
  });
});

describe("getOccupancy — capacity + full gate", () => {
  beforeEach(() => { idx = 0; });

  it("uncapped: never full, free/effectiveFree null", () => {
    setSite({ capacity: null });
    entry("A");
    const o = getOccupancy(db);
    expect(o.full).toBe(false);
    expect(o.free).toBeNull();
    expect(o.effectiveFree).toBeNull();
  });

  it("capped: full when count reaches capacity", () => {
    setSite({ capacity: 2 });
    entry("A");
    expect(getOccupancy(db).full).toBe(false);
    entry("B");
    const o = getOccupancy(db);
    expect(o.full).toBe(true);
    expect(o.free).toBe(0);
  });
});

describe("reservedSubscriberSpots", () => {
  beforeEach(() => { idx = 0; });

  function addSub(id: string, opts: Partial<typeof subscriptions.$inferInsert> = {}) {
    db.insert(subscriptions).values({ id, status: "active", quantity: 1, period: "month", ...opts }).run();
  }

  it("is 0 when the toggle is off (default)", () => {
    setSite({ capacity: 10, reserveSubscriberSpots: false });
    addSub("s1", { quantity: 2 });
    expect(reservedSubscriberSpots(db)).toBe(0);
  });

  it("holds quantity spots for an active, not-parked subscription", () => {
    setSite({ capacity: 10, reserveSubscriberSpots: true });
    addSub("s1", { quantity: 2 });
    expect(reservedSubscriberSpots(db)).toBe(2);
  });

  it("does NOT double-count a subscriber already parked (holds only the rest)", () => {
    setSite({ capacity: 10, reserveSubscriberSpots: true });
    addSub("s1", { quantity: 2 });
    // One of the family's two cars is inside (occurrence entry carries permitId = sub id).
    entry("SUBSESS-1", { permitId: "s1" });
    expect(reservedSubscriberSpots(db)).toBe(1); // 2 quantity − 1 inside
  });

  it("ignores suspended/revoked and out-of-window subscriptions", () => {
    setSite({ capacity: 10, reserveSubscriberSpots: true });
    addSub("active", { quantity: 1 });
    addSub("suspended", { quantity: 5, status: "suspended" });
    addSub("expired", { quantity: 5, validTo: "2000-01-01T00:00:00.000Z" });
    expect(reservedSubscriberSpots(db)).toBe(1);
  });
});

describe("getOccupancy — reserved tightens the transient gate", () => {
  beforeEach(() => { idx = 0; });

  it("transient sees full once count + reserved ≥ capacity", () => {
    setSite({ capacity: 3, reserveSubscriberSpots: true });
    db.insert(subscriptions).values({ id: "s1", status: "active", quantity: 2, period: "month" }).run();
    entry("A"); // 1 inside + 2 reserved = 3 ≥ capacity 3
    const o = getOccupancy(db);
    expect(o.reserved).toBe(2);
    expect(o.effectiveFree).toBe(0);
    expect(o.full).toBe(true);
  });
});