import { describe, it, expect } from "vitest";
import {
  tokenize,
  jaccard,
  priceScore,
  scoreCandidate,
  scoreOrderVsQuote,
  RULE_POINTS,
  MATCH_CONFIDENCE_THRESHOLD,
  pairQuoteLines,
  LINE_PAIR_CONFIDENT,
  LINE_PAIR_POSSIBLE,
  quoteWindowForOrder,
  quoteToOrderAgeDays,
  FUZZY_WINDOW_DAYS,
  FUZZY_WINDOW_WIDEN_DAYS,
} from "@/lib/server/order-quote-match";

/**
 * Unit tests for the pure scoring helpers inside the order ↔ quote
 * matcher. PB-dependent helpers (findExactMatch, findFuzzyMatches) are
 * exercised via the live-PB smoke test — here we just lock the math.
 *
 * The helpers live in src/lib/server/order-quote-match.ts so they're
 * testable without touching PocketBase. pb-helpers re-exports them
 * for the matcher API to use.
 */

describe("matcher scoring math", () => {
  // ─── Tokenizer ──────────────────────────────────────────────────
  it("tokenize drops short / stopword tokens", () => {
    const tokens = tokenize("M20 x 40 SET CW NUTS for testing");
    // "x" dropped (1 char), "for" dropped (stopword), "cw" dropped (2 char)
    expect(tokens.has("m20")).toBe(true);
    expect(tokens.has("set")).toBe(true);
    expect(tokens.has("nuts")).toBe(true);
    expect(tokens.has("testing")).toBe(true);
    expect(tokens.has("x")).toBe(false);
    expect(tokens.has("for")).toBe(false);
  });

  it("tokenize is case-insensitive and punctuation-tolerant", () => {
    const a = tokenize("Cable Gland M20");
    const b = tokenize("cable-gland/m20!");
    expect(a).toEqual(b);
  });

  // ─── Jaccard ────────────────────────────────────────────────────
  it("jaccard returns 1.0 for identical sets, 0.0 for disjoint", () => {
    const a = new Set(["m20", "nuts", "bolt"]);
    expect(jaccard(a, a)).toBe(1);
    expect(jaccard(a, new Set(["unrelated"]))).toBe(0);
  });

  it("jaccard returns the right overlap ratio", () => {
    // |a ∩ b| = 1 ("m20"), |a ∪ b| = 5 (m20, nuts, bolt, washer, spring)
    // → 1/5 = 0.2
    const a = new Set(["m20", "nuts", "bolt"]);
    const b = new Set(["m20", "washer", "spring"]);
    expect(jaccard(a, b)).toBeCloseTo(1 / 5, 5);
  });

  it("jaccard returns 0 for two empty sets (no signal, not 1)", () => {
    expect(jaccard(new Set(), new Set())).toBe(0);
  });

  // ─── Price score ───────────────────────────────────────────────
  it("priceScore is 1.0 when sums are equal or within 5%", () => {
    expect(priceScore(100, 100)).toBe(1);
    expect(priceScore(100, 104)).toBe(1); // 4% diff
  });

  it("priceScore is 0.0 when sums differ by 50%+", () => {
    expect(priceScore(100, 50)).toBe(0);
    expect(priceScore(100, 200)).toBe(0);
  });

  it("priceScore falls off linearly between 5% and 50%", () => {
    // At 27.5% diff (midpoint) the score should be ~0.5.
    // Linear: 1 - (0.275 - 0.05) / 0.45 = 1 - 0.5 = 0.5
    expect(priceScore(100, 72.5)).toBeCloseTo(0.5, 1);
  });

  it("priceScore returns 0 when one side is 0 (no signal)", () => {
    expect(priceScore(0, 100)).toBe(0);
    expect(priceScore(100, 0)).toBe(0);
  });

  // ─── Composite score ──────────────────────────────────────────
  it("scoreCandidate prefers descriptions over price-only match", () => {
    const orderItems = [
      { description: "M20 x 40 nuts", selling_price: 100, quantity: 1 },
    ];
    // Perfect desc match, perfect price → score ~1
    const perfect = scoreCandidate(orderItems, [
      { description: "M20 x 40 nuts", selling_price: 100, quantity: 1 },
    ]);
    // Good price but totally different description → score low
    const priceOnly = scoreCandidate(orderItems, [
      { description: "completely different thing", selling_price: 100, quantity: 1 },
    ]);
    expect(perfect).toBeGreaterThan(priceOnly);
  });

  it("scoreCandidate returns 0 for empty order items", () => {
    expect(scoreCandidate([], [{ description: "anything", selling_price: 100, quantity: 1 }])).toBe(0);
  });

  // ─── Threshold sanity ─────────────────────────────────────────
  // The rule-based scorer exposes its breakdown to the UI, so an
  // operator can audit each signal even on a low-confidence match —
  // that auditability means a more lenient threshold (0.4) is honest
  // here than it was on the old description+price composite. Pin
  // the value so any further change forces a conscious edit and a
  // look at the operator experience.
  it("confidence threshold is permissive but not zero (0.4) — breakdown-backed", () => {
    expect(MATCH_CONFIDENCE_THRESHOLD).toBe(0.4);
  });
});

/* ============================================================================
 * scoreOrderVsQuote — rule-based scoring tests
 *
 * Each test exercises one branch of the rule budget so a future refactor
 * can't silently drop a signal. Tests use full point values (RULE_POINTS)
 * to keep expectations in lock-step with the implementation.
 * ========================================================================== */

describe("scoreOrderVsQuote — header signals", () => {
  it("awards full company points when relations match exactly", () => {
    const r = scoreOrderVsQuote(
      {
        companyId: "co-1",
        customerId: null,
        items: [{ description: "M20 nuts", selling_price: 5, quantity: 10 }],
      },
      {
        company: "co-1",
        customer: null,
        items: [{ description: "M20 nuts", selling_price: 5, quantity: 10 }],
      }
    );
    expect(r.company).toBe(RULE_POINTS.company);
  });

  it("does not award customer points when order has no customer", () => {
    const r = scoreOrderVsQuote(
      {
        companyId: "co-1",
        customerId: null,
        items: [{ description: "thing", selling_price: 5, quantity: 1 }],
      },
      {
        company: "co-1",
        customer: null,
        items: [{ description: "thing", selling_price: 5, quantity: 1 }],
      }
    );
    expect(r.customer).toBeNull();
  });

  it("awards 0 customer when order has a customer but quote doesn't", () => {
    const r = scoreOrderVsQuote(
      {
        companyId: "co-1",
        customerId: "cu-9",
        items: [{ description: "x", selling_price: 5, quantity: 1 }],
      },
      {
        company: "co-1",
        customer: null,
        items: [{ description: "x", selling_price: 5, quantity: 1 }],
      }
    );
    expect(r.customer).toBe(0);
  });

  it("awards full customer points when both sides match", () => {
    const r = scoreOrderVsQuote(
      {
        companyId: "co-1",
        customerId: "cu-9",
        items: [{ description: "thing", selling_price: 5, quantity: 1 }],
      },
      {
        company: "co-1",
        customer: "cu-9",
        items: [{ description: "thing", selling_price: 5, quantity: 1 }],
      }
    );
    expect(r.customer).toBe(RULE_POINTS.customer);
  });
});

describe("scoreOrderVsQuote — per-line signals", () => {
  it("awards +2 description when per-line Jaccard >= 0.5", () => {
    const r = scoreOrderVsQuote(
      {
        items: [
          { description: "M20 x 40 SET nuts washers bolts", selling_price: 10, quantity: 5 },
        ],
      },
      {
        items: [
          // identical tokens
          { description: "M20 x 40 SET nuts washers bolts", selling_price: 10, quantity: 5 },
        ],
      }
    );
    expect(r.description).toBe(RULE_POINTS.descriptionFull);
    expect(r.lines[0].descMatched).toBe(true);
  });

  it("awards partial description (1pt) for moderate overlap (0.3..0.5)", () => {
    // Need tokens that overlap strongly enough to clear the 0.3 floor
    // but stay below 0.5 to exercise the partial-credits branch.
    // order tokens {m20, nuts, abc} (3) vs quote tokens {m20, nuts, xyz, qqq}
    // → |∩|=2 (m20, nuts), |∪|=5 → 2/5 = 0.4 → partial credit (+1).
    const r = scoreOrderVsQuote(
      {
        items: [
          { description: "M20 nuts abc", selling_price: 10, quantity: 1 },
        ],
      },
      {
        items: [
          { description: "M20 nuts xyz qqq", selling_price: 10, quantity: 1 },
        ],
      }
    );
    expect(r.description).toBe(RULE_POINTS.descriptionPartial);
    expect(r.lines[0].descMatched).toBe(true);
  });

  it("awards -1 quantity when order line and matched quote line disagree on qty", () => {
    const r = scoreOrderVsQuote(
      {
        items: [{ description: "M20 nuts washers", selling_price: 10, quantity: 5 }],
      },
      {
        items: [{ description: "M20 nuts washers", selling_price: 10, quantity: 10 }],
      }
    );
    // Same description (full +2), same price (+2), qty mismatched (-1)
    expect(r.description).toBe(RULE_POINTS.descriptionFull);
    expect(r.price).toBe(RULE_POINTS.price);
    expect(r.quantity).toBe(RULE_POINTS.quantityMismatch);
    expect(r.lines[0].qtyMatched).toBe(false);
  });

  it("awards 0 price when prices differ by more than 5%", () => {
    const r = scoreOrderVsQuote(
      {
        items: [
          { description: "M20 nuts washers", selling_price: 10, quantity: 5 },
        ],
      },
      {
        items: [
          { description: "M20 nuts washers", selling_price: 50, quantity: 5 },
        ],
      }
    );
    expect(r.price).toBe(0);
    expect(r.lines[0].priceMatched).toBe(false);
  });
});

describe("scoreOrderVsQuote — item-count penalty", () => {
  it("deducts -2 when item count differs by 50% or more", () => {
    const r = scoreOrderVsQuote(
      {
        items: [
          { description: "alpha", selling_price: 1, quantity: 1 },
          { description: "beta", selling_price: 1, quantity: 1 },
        ],
      },
      {
        items: [
          { description: "alpha", selling_price: 1, quantity: 1 },
          { description: "beta", selling_price: 1, quantity: 1 },
          // 4 lines (delta=2, max=4, diffRatio=0.5 → penalty)
          { description: "gamma", selling_price: 1, quantity: 1 },
          { description: "delta", selling_price: 1, quantity: 1 },
        ],
      }
    );
    expect(r.itemCountDelta).toBe(RULE_POINTS.itemCountPenalty50);
    expect(r.orderItemCount).toBe(2);
    expect(r.quoteItemCount).toBe(4);
  });

  it("deducts -1 when item count differs by 25-50%", () => {
    // 3 vs 5 (delta=2, max=5, ratio=0.4) → penalty -1
    const r = scoreOrderVsQuote(
      {
        items: [
          { description: "alpha", selling_price: 1, quantity: 1 },
          { description: "beta", selling_price: 1, quantity: 1 },
          { description: "gamma", selling_price: 1, quantity: 1 },
        ],
      },
      {
        items: [
          { description: "alpha", selling_price: 1, quantity: 1 },
          { description: "beta", selling_price: 1, quantity: 1 },
          { description: "gamma", selling_price: 1, quantity: 1 },
          { description: "delta", selling_price: 1, quantity: 1 },
          { description: "epsilon", selling_price: 1, quantity: 1 },
        ],
      }
    );
    expect(r.itemCountDelta).toBe(RULE_POINTS.itemCountPenalty25);
  });

  it("does not penalize identical item counts", () => {
    const r = scoreOrderVsQuote(
      {
        items: [
          { description: "alpha", selling_price: 1, quantity: 1 },
          { description: "beta", selling_price: 1, quantity: 1 },
          { description: "gamma", selling_price: 1, quantity: 1 },
        ],
      },
      {
        items: [
          { description: "alpha", selling_price: 1, quantity: 1 },
          { description: "beta", selling_price: 1, quantity: 1 },
          { description: "gamma", selling_price: 1, quantity: 1 },
        ],
      }
    );
    expect(r.itemCountDelta).toBe(0);
  });
});

describe("scoreOrderVsQuote — normalization & thresholding", () => {
  it("normalizes to 0..1 with bounded ceilings across order sizes", () => {
    // A 1-line order that perfectly matches its 1-line quote should
    // land near 1.0 the same way a 5-line order that perfectly matches
    // its 5-line quote does — per-line signals dominate raw points
    // and observedMax scales with line count.
    const oneLine = scoreOrderVsQuote(
      {
        companyId: "co-1",
        customerId: "cu-9",
        items: [{ description: "M20 nuts", selling_price: 10, quantity: 5 }],
      },
      {
        company: "co-1",
        customer: "cu-9",
        items: [{ description: "M20 nuts", selling_price: 10, quantity: 5 }],
      }
    );
    expect(oneLine.confidence).toBeGreaterThan(0.9);
    expect(oneLine.confidence).toBeLessThanOrEqual(1);
  });

  it("clamps confidence at 1.0 even when raw points exceed observedMax", () => {
    // Construct a case where header signals exist but only 1 line matches:
    // company+customer contribute 5, but only 1 line pair → 5 + 5 raw
    // vs observedMax 5 + 5 = 10 → 1.0. The clamp guarantees the bound.
    const r = scoreOrderVsQuote(
      {
        companyId: "co-1",
        customerId: "cu-9",
        items: [
          { description: "M20 nuts", selling_price: 10, quantity: 5 },
          { description: "excess line one", selling_price: 1, quantity: 1 },
          { description: "excess line two", selling_price: 1, quantity: 1 },
        ],
      },
      {
        company: "co-1",
        customer: "cu-9",
        items: [{ description: "M20 nuts", selling_price: 10, quantity: 5 }],
      }
    );
    expect(r.confidence).toBeLessThanOrEqual(1);
    expect(r.confidence).toBeGreaterThan(0);
  });

  it("returns 0 confidence when both sides have no items", () => {
    const r = scoreOrderVsQuote(
      { items: [] },
      { items: [{ description: "anything", selling_price: 1, quantity: 1 }] }
    );
    expect(r.confidence).toBe(0);
  });

  it("floors confidence at 0 (raw points can be negative)", () => {
    // Force negative: company null, customer 0, paired line mismatched qty,
    // itemCount penalty 50. Should clamp at 0 not go negative.
    const r = scoreOrderVsQuote(
      {
        // No companyId, no customerId → header signals are absent.
        items: [{ description: "completely different SKU", selling_price: 10, quantity: 5 }],
      },
      {
        company: "co-1", // mismatched → null
        customer: "cu-9", // order has no customer → null
        items: [
          { description: "another thing entirely", selling_price: 50, quantity: 50 },
        ],
      }
    );
    expect(r.confidence).toBe(0);
  });

  it("surfaces a breakdown with per-line points the UI can render", () => {
    const r = scoreOrderVsQuote(
      {
        companyId: "co-1",
        customerId: "cu-9",
        items: [
          { description: "M20 nuts washers", selling_price: 10, quantity: 5 },
        ],
      },
      {
        company: "co-1",
        customer: "cu-9",
        items: [
          { description: "M20 nuts washers", selling_price: 10, quantity: 5 },
        ],
      }
    );
    expect(r.lines).toHaveLength(1);
    expect(r.lines[0].descMatched).toBe(true);
    expect(r.lines[0].priceMatched).toBe(true);
    expect(r.lines[0].qtyMatched).toBe(true);
    expect(r.lines[0].points).toBeGreaterThan(0);
  });
});

describe("scoreOrderVsQuote — needs a paired line", () => {
  // A quote that shares nothing with the order is not a candidate,
  // however well the header matches. Same company (+3) plus same
  // customer (+2) used to score 0.5 with zero paired lines, which is
  // how one quote ended up suggested to 16 different orders.
  it("scores 0 when company and customer match but no line pairs (270555-MOB vs Q002997)", () => {
    const r = scoreOrderVsQuote(
      { companyId: "co", customerId: "cu", items: [{ description: 'Funnel 150mm PVC round 2 piece Flexible ("6") Round', selling_price: 16.64, quantity: 1 }] },
      { company: "co", customer: "cu", items: [{ description: "22mm endurance +", selling_price: 1655.76, quantity: 1 }] },
    );
    expect(r.company).toBe(RULE_POINTS.company);
    expect(r.customer).toBe(RULE_POINTS.customer);
    expect(r.confidence).toBe(0);
  });
  it("scores 0 against a quote with no lines", () => {
    const r = scoreOrderVsQuote(
      { companyId: "co", customerId: "cu", items: [{ description: "M16 bolt", selling_price: 3, quantity: 10 }] },
      { company: "co", customer: "cu", items: [] },
    );
    expect(r.confidence).toBe(0);
  });
  it("still scores above threshold when one line pairs", () => {
    const r = scoreOrderVsQuote(
      { companyId: "co", customerId: "cu", items: [{ description: "Flat washer M16 zinc", selling_price: 1, quantity: 100 }] },
      { company: "co", customer: "cu", items: [{ description: "Flat washer M16 zinc plated", selling_price: 1, quantity: 100 }] },
    );
    expect(r.confidence).toBeGreaterThanOrEqual(MATCH_CONFIDENCE_THRESHOLD);
  });
});

describe("pairQuoteLines", () => {
  it("tiers a near-identical line as confident", () => {
    const pairs = pairQuoteLines(
      [{ description: "M20 HEX BOLT GR8.8 ZINC" }],
      [{ description: "Hex Bolt M20 Gr8.8 Zinc" }],
    );
    expect(pairs).toHaveLength(1);
    expect(pairs[0].orderLineIdx).toBe(0);
    expect(pairs[0].quoteLineIdx).toBe(0);
    expect(pairs[0].tier).toBe("confident");
  });

  it("tiers a partial-overlap line as possible", () => {
    const pairs = pairQuoteLines(
      [{ description: "cable gland brass M20" }],
      [{ description: "cable gland stainless M25" }],
    );
    expect(pairs).toHaveLength(1);
    expect(pairs[0].tier).toBe("possible");
    expect(pairs[0].jaccard).toBeGreaterThanOrEqual(LINE_PAIR_POSSIBLE);
    expect(pairs[0].jaccard).toBeLessThan(LINE_PAIR_CONFIDENT);
  });

  it("tiers an exact 0.5 boundary as confident (inclusive)", () => {
    // order tokens {cable, gland, brass} (3), quote tokens {cable,
    // gland, brass, steel, nickel, plated} (6) → |∩|=3, |∪|=6 → 3/6 = 0.5
    const pairs = pairQuoteLines(
      [{ description: "cable gland brass" }],
      [{ description: "cable gland brass steel nickel plated" }],
    );
    expect(pairs).toHaveLength(1);
    expect(pairs[0].jaccard).toBe(LINE_PAIR_CONFIDENT);
    expect(pairs[0].tier).toBe("confident");
  });

  it("returns no pair when descriptions do not overlap", () => {
    const pairs = pairQuoteLines(
      [{ description: "galvanised threaded rod 3 metre" }],
      [{ description: "silicone sealant clear cartridge" }],
    );
    expect(pairs).toEqual([]);
  });

  it("never pairs one quote line to two order lines", () => {
    const pairs = pairQuoteLines(
      [
        { description: "hex bolt m20 gr8.8 zinc" },
        { description: "hex bolt m20 gr8.8 zinc" },
      ],
      [{ description: "hex bolt m20 gr8.8 zinc" }],
    );
    expect(pairs).toHaveLength(1);
    const quoteIdxs = pairs.map((p) => p.quoteLineIdx);
    expect(new Set(quoteIdxs).size).toBe(quoteIdxs.length);
  });
});

describe("quoteWindowForOrder", () => {
  const ORDER_DATE = "2026-08-29T10:00:00.000Z";

  it("looks back the requested number of days from the ORDER date, not from now", () => {
    const w = quoteWindowForOrder(ORDER_DATE, 90);
    expect(w.from).toBe("2026-05-31T10:00:00.000Z");
  });

  it("extends forward by the grace period so a quote raised just after the PO still matches", () => {
    const w = quoteWindowForOrder(ORDER_DATE, 90);
    expect(w.to).toBe("2026-09-05T10:00:00.000Z");
  });

  it("widens correctly for the fallback pass", () => {
    const w = quoteWindowForOrder(ORDER_DATE, FUZZY_WINDOW_WIDEN_DAYS);
    expect(new Date(w.from).getTime()).toBeLessThan(
      new Date(quoteWindowForOrder(ORDER_DATE, FUZZY_WINDOW_DAYS).from).getTime(),
    );
  });

  it("throws on an unparseable order date rather than silently matching everything", () => {
    expect(() => quoteWindowForOrder("not-a-date", 90)).toThrow(/unparseable/i);
  });

  it("accepts PocketBase's space-separated datetime form identically to the ISO T form", () => {
    const iso = quoteWindowForOrder(ORDER_DATE, 90);
    const pbForm = quoteWindowForOrder("2026-08-29 10:00:00.000Z", 90);
    expect(pbForm).toEqual(iso);
  });
});

describe("quoteToOrderAgeDays", () => {
  it("returns a positive day count when the quote precedes the order (normal case)", () => {
    // Quote created 2026-06-01, order created 2026-08-29 → quote first,
    // order 89 days later.
    const days = quoteToOrderAgeDays(
      "2026-06-01T10:00:00.000Z",
      "2026-08-29T10:00:00.000Z",
    );
    expect(days).toBe(89);
  });

  it("returns a negative day count when the quote is created after the order (inverted case)", () => {
    // Quote created 5 days after the order.
    const days = quoteToOrderAgeDays(
      "2026-08-29T10:00:00.000Z",
      "2026-08-24T10:00:00.000Z",
    );
    expect(days).toBe(-5);
  });

  it("returns 0 (not NaN) when either input is unparseable", () => {
    expect(quoteToOrderAgeDays("not-a-date", "2026-08-29T10:00:00.000Z")).toBe(0);
    expect(quoteToOrderAgeDays("2026-08-29T10:00:00.000Z", "not-a-date")).toBe(0);
    expect(Number.isNaN(quoteToOrderAgeDays("garbage", "also-garbage"))).toBe(false);
  });

  it("returns a clean 0, not -0, when the quote lands exactly half a day after the order", () => {
    // Quote created 12h after the order → (order - quote) = -0.5 days.
    // Math.round(-0.5) is -0 in JS; the function must normalize that.
    const days = quoteToOrderAgeDays(
      "2026-08-29T22:00:00.000Z",
      "2026-08-29T10:00:00.000Z",
    );
    expect(days).toBe(0);
    expect(Object.is(days, -0)).toBe(false);
    expect(Object.is(days, 0)).toBe(true);
  });

  it("accepts PocketBase's space-separated datetime form identically to the ISO T form", () => {
    const iso = quoteToOrderAgeDays(
      "2026-06-01T10:00:00.000Z",
      "2026-08-29T10:00:00.000Z",
    );
    const pbForm = quoteToOrderAgeDays(
      "2026-06-01 10:00:00.000Z",
      "2026-08-29 10:00:00.000Z",
    );
    expect(pbForm).toBe(iso);
    expect(pbForm).toBe(89);
  });
});