import { describe, it, expect } from "vitest";
import {
  fyStartYear,
  fyLabel,
  fyMonthIndex,
  weekOfMonth,
  buildAccountIndex,
  costCentreRows,
  costCentreWeekly,
  accountNodeSpend,
  accountNodeWeekly,
  accountLevelRows,
  topAccountsForCostCentre,
  costCentresForAccount,
  childBreakdown,
  applyScope,
  parseScope,
  parseGranularity,
  resolveFy,
  resolveMonth,
  parseSel,
  toggleSel,
  allocatePoSpend,
  type ReportDataset,
  type AccountNode,
} from "@/lib/reports";

const ACCOUNTS: AccountNode[] = [
  { id: "H", code: "5000", name: "Operating", parentId: null, tier: "Heading" },
  { id: "S", code: "5100", name: "Vessel Running", parentId: "H", tier: "Sub-heading" },
  { id: "L1", code: "5110", name: "Fuel", parentId: "S", tier: "Leaf" },
  { id: "L2", code: "5120", name: "Spares", parentId: "S", tier: "Leaf" },
];

// fys ascending: [2024, 2025]. PO p1 is multi-account (rows on L1 + L2).
const DS: ReportDataset = {
  vessels: [
    { id: "v1", code: "V1", name: "MV One" },
    { id: "v2", code: "V2", name: "MV Two" },
  ],
  accounts: ACCOUNTS,
  fys: [2024, 2025],
  rows: [
    { poId: "p1", vesselId: "v1", accountId: "L1", amount: 100, fy: 2025, month: 0, week: 0 },
    { poId: "p2", vesselId: "v1", accountId: "L1", amount: 50, fy: 2025, month: 1, week: 1 },
    { poId: "p1", vesselId: "v1", accountId: "L2", amount: 30, fy: 2025, month: 0, week: 0 },
    { poId: "p3", vesselId: "v2", accountId: "L1", amount: 200, fy: 2024, month: 5, week: 0 },
    { poId: "p4", vesselId: "v2", accountId: "L2", amount: 70, fy: 2025, month: 11, week: 2 },
  ],
};

describe("financial-year helpers", () => {
  it("maps Apr–Mar to the Indian FY start year", () => {
    expect(fyStartYear(new Date(2025, 3, 1))).toBe(2025); // Apr
    expect(fyStartYear(new Date(2025, 0, 15))).toBe(2024); // Jan → prior FY
    expect(fyStartYear(new Date(2025, 2, 31))).toBe(2024); // Mar → prior FY
  });
  it("labels and indexes months within the FY", () => {
    expect(fyLabel(2025)).toBe("FY 2025–26");
    expect(fyMonthIndex(new Date(2025, 3, 1))).toBe(0); // Apr
    expect(fyMonthIndex(new Date(2026, 2, 1))).toBe(11); // Mar
  });
});

describe("costCentreRows", () => {
  it("totals the selected FY by vessel with a 12-month series and PO count", () => {
    const rows = costCentreRows(DS, 2025);
    const v1 = rows.find((r) => r.id === "v1")!;
    expect(v1.total).toBe(180);
    expect(v1.months[0]).toBe(130); // 100 + 30
    expect(v1.months[1]).toBe(50);
    expect(v1.poCount).toBe(2); // distinct POs (p1 is multi-account, + p2) — not row count
    expect(v1.fyTotals).toEqual([0, 180]); // [2024, 2025]

    const v2 = rows.find((r) => r.id === "v2")!;
    expect(v2.total).toBe(70);
    expect(v2.fyTotals).toEqual([200, 70]);
  });
});

describe("accounting-code rollup", () => {
  const idx = buildAccountIndex(ACCOUNTS);
  it("rolls leaf spend up to the heading", () => {
    expect(accountNodeSpend(DS, idx, "H", 2025).total).toBe(250); // 100+50+30+70
    expect(accountNodeSpend(DS, idx, "L1", 2025).total).toBe(150);
  });
  it("lists the children to compare at a drill level", () => {
    const top = accountLevelRows(DS, idx, null, 2025); // headings
    expect(top.map((r) => r.node.id)).toEqual(["H"]);
    const subs = accountLevelRows(DS, idx, "H", 2025);
    expect(subs.map((r) => r.node.id)).toEqual(["S"]);
  });
  it("leaf detection and leaf set", () => {
    expect(idx.isLeaf("L1")).toBe(true);
    expect(idx.isLeaf("H")).toBe(false);
    expect([...idx.leavesUnder("H")].sort()).toEqual(["L1", "L2"]);
  });
});

describe("breakdowns", () => {
  const idx = buildAccountIndex(ACCOUNTS);
  it("top accounting codes for a cost centre (by tier)", () => {
    const bd = topAccountsForCostCentre(DS, idx, "v1", 2025, "Leaf");
    expect(bd.map((b) => [b.id, b.value])).toEqual([
      ["L1", 150],
      ["L2", 30],
    ]);
  });
  it("cost centres for an account node", () => {
    const bd = costCentresForAccount(DS, idx, "H", 2025);
    expect(bd.map((b) => [b.id, b.value])).toEqual([
      ["v1", 180],
      ["v2", 70],
    ]);
  });
  it("child breakdown of a non-leaf node", () => {
    const bd = childBreakdown(DS, idx, "H", 2025);
    expect(bd).toEqual([{ id: "S", label: "5100 · Vessel Running", value: 250 }]);
  });
});

describe("line-item account allocation (#3)", () => {
  const po = { id: "po9", vesselId: "v1", accountId: "L1", amount: 100, fy: 2025, month: 0, week: 0 };
  it("splits a PO proportionally across its line-item accounts, summing back to the PO total", () => {
    const out = allocatePoSpend(po, [
      { accountId: "L1", amount: 30 },
      { accountId: "L2", amount: 90 },
    ]);
    const byAcc = Object.fromEntries(out.map((r) => [r.accountId, r.amount]));
    expect(byAcc["L1"]).toBeCloseTo(25); // 100 * 30/120
    expect(byAcc["L2"]).toBeCloseTo(75); // 100 * 90/120
    expect(out.reduce((s, r) => s + r.amount, 0)).toBeCloseTo(100);
    expect(out.every((r) => r.poId === "po9" && r.vesselId === "v1")).toBe(true);
  });
  it("falls a line with no account back to the PO-level account", () => {
    const out = allocatePoSpend(po, [{ accountId: null, amount: 10 }, { accountId: "L2", amount: 10 }]);
    expect(Object.fromEntries(out.map((r) => [r.accountId, r.amount]))).toEqual({ L1: 50, L2: 50 });
  });
  it("puts the whole amount on the PO account when there are no line items", () => {
    expect(allocatePoSpend(po, [])).toEqual([{ poId: "po9", vesselId: "v1", accountId: "L1", amount: 100, fy: 2025, month: 0, week: 0 }]);
  });
});

describe("weekly buckets (#1)", () => {
  const idx = buildAccountIndex(ACCOUNTS);
  it("computes week-of-month from the day", () => {
    expect(weekOfMonth(new Date(2025, 3, 1))).toBe(0);
    expect(weekOfMonth(new Date(2025, 3, 8))).toBe(1);
    expect(weekOfMonth(new Date(2025, 3, 29))).toBe(4);
  });
  it("buckets a month's spend into weeks for a cost centre and an account node", () => {
    expect(costCentreWeekly(DS, "v1", 2025, 0)).toEqual([130, 0, 0, 0, 0]); // both month-0 rows in W1
    expect(accountNodeWeekly(DS, idx, "H", 2025, 0)).toEqual([130, 0, 0, 0, 0]);
  });
});

describe("custom selection (#2)", () => {
  it("parses and de-dupes ?sel=", () => {
    expect(parseSel("a,b,a, ,c")).toEqual(["a", "b", "c"]);
    expect(parseSel(undefined)).toEqual([]);
  });
  it("toggles ids in and out", () => {
    expect(toggleSel(["a", "b"], "a")).toEqual(["b"]);
    expect(toggleSel(["a"], "b")).toEqual(["a", "b"]);
  });
});

describe("scope + param parsing", () => {
  it("applies Top/Bottom-N to a descending list", () => {
    const sorted = [5, 4, 3, 2, 1];
    expect(applyScope(sorted, "top5")).toEqual([5, 4, 3, 2, 1]);
    expect(applyScope([9, 8, 7, 6, 5, 4, 3, 2, 1, 0, -1], "top10")).toHaveLength(10);
    expect(applyScope(sorted, "bottom5")).toEqual([1, 2, 3, 4, 5]);
    expect(applyScope(sorted, "all")).toEqual(sorted);
  });
  it("parses scope + resolves FY with sensible defaults", () => {
    expect(parseScope("top10")).toBe("top10");
    expect(parseScope("garbage")).toBe("top5");
    expect(resolveFy(DS, "2024")).toBe(2024);
    expect(resolveFy(DS, undefined)).toBe(2025); // latest
    expect(resolveFy(DS, "1999")).toBe(2025); // out of range → latest
  });
  it("parses granularity (incl. weekly) and resolves the weekly month", () => {
    expect(parseGranularity("weekly")).toBe("weekly");
    expect(parseGranularity("yearly")).toBe("yearly");
    expect(parseGranularity(undefined)).toBe("monthly");
    expect(resolveMonth(DS, 2025, undefined)).toBe(11); // latest month with spend in FY2025
    expect(resolveMonth(DS, 2025, "3")).toBe(3);
    expect(resolveMonth(DS, 2025, "99")).toBe(11); // out of range → latest
  });
});