import { describe, it, expect } from "vitest";
import {
  fyStartYear,
  fyLabel,
  fyMonthIndex,
  buildAccountIndex,
  costCentreRows,
  accountNodeSpend,
  accountLevelRows,
  topAccountsForCostCentre,
  costCentresForAccount,
  childBreakdown,
  applyScope,
  parseScope,
  resolveFy,
  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]
const DS: ReportDataset = {
  vessels: [
    { id: "v1", code: "V1", name: "MV One" },
    { id: "v2", code: "V2", name: "MV Two" },
  ],
  accounts: ACCOUNTS,
  fys: [2024, 2025],
  rows: [
    { vesselId: "v1", accountId: "L1", amount: 100, fy: 2025, month: 0 },
    { vesselId: "v1", accountId: "L1", amount: 50, fy: 2025, month: 1 },
    { vesselId: "v1", accountId: "L2", amount: 30, fy: 2025, month: 0 },
    { vesselId: "v2", accountId: "L1", amount: 200, fy: 2024, month: 5 },
    { vesselId: "v2", accountId: "L2", amount: 70, fy: 2025, month: 11 },
  ],
};

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(3);
    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("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
  });
});