import type { DateTime } from "@batch-cooking/date-tools";
import { ErrorCode, type SignupInput } from "@batch-cooking/shared";
import { faker } from "@faker-js/faker";
import { expect } from "chai";
import request from "supertest";
import { createApp } from "../src/app.js";
import { prisma } from "../src/db/prisma.js";
import { TEST_REFERENCE_DATE } from "../test-support/reference-date.js";
import { resetDatabase } from "../test-support/reset-db.js";

/** See `auth.test.ts` — same rationale for generating rather than hardcoding. */
function buildSignupPayload(): SignupInput {
  const firstName = faker.person.firstName();
  const lastName = faker.person.lastName();
  return {
    firstName,
    lastName,
    email: faker.internet.email({ firstName, lastName }).toLowerCase(),
    password: faker.internet.password({ length: 16 }),
  };
}

/** The fixed test "today", as the `YYYY-MM-DD` string `GET /planning`'s `?date=` expects. */
function today(): string {
  return isoDate(TEST_REFERENCE_DATE);
}

/** `toISODate()` only returns `null` for an invalid `DateTime` — never the case for the always-valid values built in this file. */
function isoDate(date: DateTime): string {
  const iso = date.toISODate();
  if (iso === null) throw new Error("Unexpectedly invalid DateTime in a test helper");
  return iso;
}

describe("Planning", () => {
  const app = createApp();

  beforeEach(async () => {
    await resetDatabase();
  });

  after(async () => {
    await prisma.$disconnect();
  });

  describe("GET /planning", () => {
    it("rejects requests without a session cookie with 401 NOT_AUTHENTICATED", async () => {
      const res = await request(app).get("/planning").query({ date: today() });

      expect(res.status).to.equal(401);
      expect(res.body.code).to.equal(ErrorCode.NOT_AUTHENTICATED);
    });

    it("rejects a missing date with 400 VALIDATION_ERROR", async () => {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());

      const res = await agent.get("/planning");

      expect(res.status).to.equal(400);
      expect(res.body.code).to.equal(ErrorCode.VALIDATION_ERROR);
    });

    it("rejects a malformed date with 400 VALIDATION_ERROR", async () => {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());

      const res = await agent.get("/planning").query({ date: "not-a-date" });

      expect(res.status).to.equal(400);
      expect(res.body.code).to.equal(ErrorCode.VALIDATION_ERROR);
    });

    it("rejects a date shaped right but calendarially impossible with 400 VALIDATION_ERROR", async () => {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());

      const res = await agent.get("/planning").query({ date: "2026-02-30" });

      expect(res.status).to.equal(400);
      expect(res.body.code).to.equal(ErrorCode.VALIDATION_ERROR);
    });

    it("returns null when the household has no planning covering that date", async () => {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());

      const res = await agent.get("/planning").query({ date: today() });

      expect(res.status).to.equal(200);
      expect(res.body).to.equal(null);
    });

    it("returns the household's planning covering that date, with recipes resolved", async () => {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());
      const houseRes = await agent.post("/house").send({ name: "Chez moi" });
      const houseId: number = houseRes.body.id;

      const recipe = await prisma.recipe.create({
        data: { name: "Ratatouille", authorId: houseRes.body.adminId, portions: 4 },
      });
      const planning = await prisma.planning.create({
        data: {
          houseId,
          startDate: TEST_REFERENCE_DATE.minus({ days: 2 }).toJSDate(),
          finishDate: TEST_REFERENCE_DATE.plus({ days: 2 }).toJSDate(),
        },
      });
      await prisma.planningItem.create({
        data: {
          planningId: planning.id,
          weekDay: "lundi",
          meal: "diner",
          recipeId: recipe.id,
          portions: 4,
          portionsRequested: 3,
        },
      });

      const res = await agent.get("/planning").query({ date: today() });

      expect(res.status).to.equal(200);
      expect(res.body.id).to.equal(planning.id);
      expect(res.body.items).to.have.length(1);
      expect(res.body.items[0]).to.include({
        weekDay: "lundi",
        meal: "diner",
        portions: 4,
        portionsRequested: 3,
        discardedPortions: 0,
      });
      expect(res.body.items[0].sourceItem).to.equal(null);
      expect(res.body.items[0].recipe).to.include({ id: recipe.id, name: "Ratatouille" });
    });

    it("returns null when the household's planning does not cover that date", async () => {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());
      const houseRes = await agent.post("/house").send({ name: "Chez moi" });
      const houseId: number = houseRes.body.id;

      // A planning entirely in the past — shouldn't be picked up for today.
      await prisma.planning.create({
        data: {
          houseId,
          startDate: new Date(Date.UTC(2000, 0, 1)),
          finishDate: new Date(Date.UTC(2000, 0, 7)),
        },
      });

      const res = await agent.get("/planning").query({ date: today() });

      expect(res.status).to.equal(200);
      expect(res.body).to.equal(null);
    });

    it("returns a different week's planning when asked for a date outside the current one", async () => {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());
      const houseRes = await agent.post("/house").send({ name: "Chez moi" });
      const houseId: number = houseRes.body.id;

      const recipe = await prisma.recipe.create({
        data: { name: "Curry de lentilles", authorId: houseRes.body.adminId, portions: 4 },
      });
      const nextWeek = TEST_REFERENCE_DATE.plus({ weeks: 1 });
      const planning = await prisma.planning.create({
        data: {
          houseId,
          startDate: nextWeek.startOf("week").toJSDate(),
          finishDate: nextWeek.endOf("week").startOf("day").toJSDate(),
        },
      });
      await prisma.planningItem.create({
        data: {
          planningId: planning.id,
          weekDay: "mardi",
          meal: "dejeuner",
          recipeId: recipe.id,
          portions: 2,
          portionsRequested: 2,
        },
      });

      const res = await agent.get("/planning").query({ date: isoDate(nextWeek) });

      expect(res.status).to.equal(200);
      expect(res.body.id).to.equal(planning.id);

      const thisWeekRes = await agent.get("/planning").query({ date: today() });
      expect(thisWeekRes.body).to.equal(null);
    });
  });

  describe("POST /planning/items", () => {
    /** Signs up, creates a household, and returns an authenticated agent + a saved recipe with the given yield. */
    async function setup(recipePortions: number) {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());
      const houseRes = await agent.post("/house").send({ name: "Chez moi" });
      const recipe = await prisma.recipe.create({
        data: { name: "Lasagnes", authorId: houseRes.body.adminId, portions: recipePortions },
      });
      return { agent, recipe };
    }

    it("rounds the prepared portions up to a whole batch of the recipe and reports the leftover", async () => {
      const { agent, recipe } = await setup(4);

      const res = await agent.post("/planning/items").send({
        date: today(),
        weekDay: "lundi",
        meal: "diner",
        recipeId: recipe.id,
        portionsRequested: 3,
      });

      expect(res.status).to.equal(201);
      // 3 requested, 4-portion recipe -> one batch of 4 prepared, 1 leftover.
      expect(res.body).to.include({ portions: 4, portionsRequested: 3, discardedPortions: 0 });
      expect(res.body.sourceItem).to.equal(null);

      const stored = await prisma.planningItem.findUnique({ where: { id: res.body.id } });
      expect(stored).to.include({ portions: 4, portionsRequested: 3 });
    });

    it("cooks several batches when more portions are requested than one batch yields", async () => {
      const { agent, recipe } = await setup(4);

      const res = await agent.post("/planning/items").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        recipeId: recipe.id,
        portionsRequested: 10,
      });

      expect(res.status).to.equal(201);
      // 10 requested, 4-portion recipe -> three batches (12) prepared, 2 leftover.
      expect(res.body).to.include({ portions: 12, portionsRequested: 10 });
    });

    it("leaves no leftover when the request lands exactly on a batch boundary", async () => {
      const { agent, recipe } = await setup(4);

      const res = await agent.post("/planning/items").send({
        date: today(),
        weekDay: "mercredi",
        meal: "diner",
        recipeId: recipe.id,
        portionsRequested: 8,
      });

      expect(res.status).to.equal(201);
      expect(res.body).to.include({ portions: 8, portionsRequested: 8 });
    });

    it("rejects a non-positive portionsRequested with 400 VALIDATION_ERROR", async () => {
      const { agent, recipe } = await setup(4);

      const res = await agent.post("/planning/items").send({
        date: today(),
        weekDay: "lundi",
        meal: "diner",
        recipeId: recipe.id,
        portionsRequested: 0,
      });

      expect(res.status).to.equal(400);
      expect(res.body.code).to.equal(ErrorCode.VALIDATION_ERROR);
    });
  });

  describe("leftovers — POST /planning/items/leftover and PATCH .../discard-leftover", () => {
    /**
     * Signs up + creates a household, saves a 4-portion recipe, and plans
     * it once with `requested` portions — so the resulting item has a
     * leftover pool of `ceil(requested/4)*4 - requested`. Returns the agent,
     * the recipe, and that source item.
     */
    async function setupWithSource(requested: number) {
      const agent = request.agent(app);
      await agent.post("/auth/signup").send(buildSignupPayload());
      const houseRes = await agent.post("/house").send({ name: "Chez moi" });
      const recipe = await prisma.recipe.create({
        data: { name: "Lasagnes", authorId: houseRes.body.adminId, portions: 4 },
      });
      const addRes = await agent.post("/planning/items").send({
        date: today(),
        weekDay: "lundi",
        meal: "diner",
        recipeId: recipe.id,
        portionsRequested: requested,
      });
      return { agent, recipe, source: addRes.body };
    }

    it("serves part of a source item's leftover pool as a new leftovers item on another slot", async () => {
      // 10 requested on a 4-portion recipe -> 12 prepared, pool of 2.
      const { agent, recipe, source } = await setupWithSource(10);
      expect(source.portions).to.equal(12);

      const res = await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        sourceItemId: source.id,
        portions: 2,
      });

      expect(res.status).to.equal(201);
      expect(res.body).to.include({
        weekDay: "mardi",
        meal: "dejeuner",
        portions: 2,
        portionsRequested: 2,
        discardedPortions: 0,
      });
      expect(res.body.sourceItem).to.deep.equal({ id: source.id });
      // The recipe is copied from the source, not sent by the client.
      expect(res.body.recipe.id).to.equal(recipe.id);
    });

    it("rejects assigning more portions than the source pool still has, with 409 LEFTOVER_QUANTITY_EXCEEDED", async () => {
      const { agent, source } = await setupWithSource(10); // pool of 2

      // Take 2 of the 2 available...
      await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        sourceItemId: source.id,
        portions: 2,
      });
      // ...then ask for 1 more — nothing left.
      const res = await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mercredi",
        meal: "diner",
        sourceItemId: source.id,
        portions: 1,
      });

      expect(res.status).to.equal(409);
      expect(res.body.code).to.equal(ErrorCode.LEFTOVER_QUANTITY_EXCEEDED);
    });

    it("404s when the source item belongs to another household", async () => {
      const { source } = await setupWithSource(10);

      const stranger = request.agent(app);
      await stranger.post("/auth/signup").send(buildSignupPayload());
      await stranger.post("/house").send({ name: "Ailleurs" });

      const res = await stranger.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        sourceItemId: source.id,
        portions: 1,
      });

      expect(res.status).to.equal(404);
      expect(res.body.code).to.equal(ErrorCode.PLANNING_ITEM_NOT_FOUND);
    });

    it("404s when the source item is itself a leftovers item (no leftovers-on-leftovers)", async () => {
      const { agent, source } = await setupWithSource(10);
      const leftover = await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        sourceItemId: source.id,
        portions: 1,
      });

      const res = await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mercredi",
        meal: "diner",
        sourceItemId: leftover.body.id,
        portions: 1,
      });

      expect(res.status).to.equal(404);
      expect(res.body.code).to.equal(ErrorCode.PLANNING_ITEM_NOT_FOUND);
    });

    it("deleting the source item cascades to every leftovers item served from it", async () => {
      const { agent, source } = await setupWithSource(10);
      const leftover = await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        sourceItemId: source.id,
        portions: 2,
      });

      await agent.delete(`/planning/items/${source.id}`).expect(204);

      const stillThere = await prisma.planningItem.findUnique({ where: { id: leftover.body.id } });
      expect(stillThere).to.equal(null);
    });

    it("discards the whole remaining pool, and is idempotent", async () => {
      const { agent, source } = await setupWithSource(10); // pool of 2

      const first = await agent.patch(`/planning/items/${source.id}/discard-leftover`);
      expect(first.status).to.equal(200);
      expect(first.body.discardedPortions).to.equal(2);

      // Nothing left — a second call changes nothing.
      const second = await agent.patch(`/planning/items/${source.id}/discard-leftover`);
      expect(second.status).to.equal(200);
      expect(second.body.discardedPortions).to.equal(2);

      // And the pool is now empty for an assignment too.
      const assign = await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        sourceItemId: source.id,
        portions: 1,
      });
      expect(assign.status).to.equal(409);
    });

    it("only discards what's still available after some was already served", async () => {
      const { agent, source } = await setupWithSource(10); // pool of 2
      await agent.post("/planning/items/leftover").send({
        date: today(),
        weekDay: "mardi",
        meal: "dejeuner",
        sourceItemId: source.id,
        portions: 1,
      });

      const res = await agent.patch(`/planning/items/${source.id}/discard-leftover`);
      expect(res.status).to.equal(200);
      // 1 of the 2 was served; only the other 1 gets discarded.
      expect(res.body.discardedPortions).to.equal(1);
    });

    it("404s discarding an unknown planning item", async () => {
      const { agent } = await setupWithSource(4);
      const res = await agent.patch("/planning/items/999999/discard-leftover");
      expect(res.status).to.equal(404);
      expect(res.body.code).to.equal(ErrorCode.PLANNING_ITEM_NOT_FOUND);
    });
  });
});