import { describe, expect, it } from "vitest";
import { fuzzy, pieces, rank } from "../src/lib/fuzzy";

describe("fuzzy", () => {
  it("matches a subsequence, not just a substring", () => {
    expect(fuzzy("wsr", "website redesign")).not.toBeNull();
    expect(fuzzy("zzz", "website redesign")).toBeNull();
  });

  it("is case insensitive and ignores surrounding space in the query", () => {
    expect(fuzzy("  WEB ", "website")).not.toBeNull();
  });

  it("returns every match for an empty query", () => {
    expect(fuzzy("", "anything")).toEqual({ score: 0, ranges: [] });
  });

  it("merges adjacent letters into one range", () => {
    expect(fuzzy("web", "website")?.ranges).toEqual([[0, 3]]);
  });

  it("keeps separate runs apart", () => {
    expect(fuzzy("wr", "website redesign")?.ranges).toEqual([
      [0, 1],
      [8, 9],
    ]);
  });

  it("scores a word start above a letter buried mid-word", () => {
    const start = fuzzy("r", "website redesign")?.score ?? 0;
    const buried = fuzzy("b", "website redesign")?.score ?? 0;
    expect(start).toBeGreaterThan(buried);
  });
});

describe("rank", () => {
  const items = ["web", "website redesign", "errands", "someday"];
  const label = (item: string): string => item;

  it("keeps the given order when nothing is typed", () => {
    expect(rank("", items, label).map((hit) => hit.item)).toEqual(items);
  });

  it("puts the shorter exact head first", () => {
    expect(rank("web", items, label)[0].item).toBe("web");
  });

  it("drops what does not match at all", () => {
    expect(rank("qq", items, label)).toEqual([]);
  });

  it("breaks ties by the incoming order", () => {
    expect(rank("e", ["ea", "eb"], label).map((hit) => hit.item)).toEqual([
      "ea",
      "eb",
    ]);
  });
});

describe("pieces", () => {
  it("splits a label into matched and unmatched runs", () => {
    expect(pieces("website", [[0, 3]])).toEqual([
      { text: "web", hit: true },
      { text: "site", hit: false },
    ]);
  });

  it("returns the whole label when nothing matched", () => {
    expect(pieces("website", [])).toEqual([{ text: "website", hit: false }]);
  });

  it("rebuilds the original text exactly", () => {
    const hit = fuzzy("wr", "website redesign");
    const parts = pieces("website redesign", hit?.ranges ?? []);
    expect(parts.map((part) => part.text).join("")).toBe("website redesign");
  });
});