import { describe, expect, test } from "bun:test";
import { filterAdvertisement, filterLsRefs } from "./ref-advertisement";
import { concatBytes, FLUSH_PKT, packetText, parseAllPackets, pktLine } from "./pktline";

const A = "a".repeat(40);
const B = "b".repeat(40);
const C = "c".repeat(40);

function lines(body: Uint8Array): string[] {
  return parseAllPackets(body).map((packet) => (packet.kind === "data" ? (packetText(packet) ?? "") : packet.kind));
}

describe("filterAdvertisement", () => {
  const body = concatBytes([
    pktLine("# service=git-upload-pack\n"),
    FLUSH_PKT,
    pktLine(`${A} HEAD\0multi_ack symref=HEAD:refs/heads/main agent=x\n`),
    pktLine(`${C} refs/gitfor/pull/r/1/base\n`),
    pktLine(`${B} refs/heads/dev\n`),
    pktLine(`${A} refs/heads/main\n`),
    FLUSH_PKT,
  ]);

  test("drops hidden refs and points HEAD at the default branch", () => {
    const out = lines(filterAdvertisement(body, "dev"));
    expect(out.some((line) => line.includes("refs/gitfor/"))).toBe(false);
    expect(out[2]).toBe(`${B} HEAD\0multi_ack agent=x symref=HEAD:refs/heads/dev`);
  });

  test("leaves HEAD alone when the default branch is missing", () => {
    const out = lines(filterAdvertisement(body, "gone"));
    expect(out[2]).toBe(`${A} HEAD\0multi_ack symref=HEAD:refs/heads/main agent=x`);
  });

  test("moves capabilities when the first ref is hidden", () => {
    const hiddenFirst = concatBytes([
      pktLine(`${C} refs/gitfor/x\0caps\n`),
      pktLine(`${B} refs/heads/dev\n`),
      FLUSH_PKT,
    ]);
    expect(lines(filterAdvertisement(hiddenFirst))[0]).toBe(`${B} refs/heads/dev\0caps`);
  });
});

describe("filterLsRefs", () => {
  test("drops hidden refs and rewrites the HEAD symref target", () => {
    const body = concatBytes([
      pktLine(`${A} HEAD symref-target:refs/heads/main\n`),
      pktLine(`${C} refs/gitfor/pull/r/1/base\n`),
      pktLine(`${B} refs/heads/dev\n`),
      pktLine(`${A} refs/heads/main\n`),
      FLUSH_PKT,
    ]);
    const out = lines(filterLsRefs(body, "dev"));
    expect(out).toEqual([
      `${B} HEAD symref-target:refs/heads/dev`,
      `${B} refs/heads/dev`,
      `${A} refs/heads/main`,
      "flush",
    ]);
  });
});