import { describe, expect, test } from "bun:test";
import { formatPatchSeries } from "./patch-format";

const commit = (sha: string, message: string) => ({
  sha,
  message,
  authorName: "Ada Lovelace",
  authorEmail: "ada@example.com",
  authoredAt: Date.UTC(2026, 9, 12, 8, 30, 0),
});

describe("formatPatchSeries", () => {
  test("a single commit is a git format-patch message git am accepts", () => {
    const text = formatPatchSeries([
      { commit: commit("a".repeat(40), "Fix parser\n\nHandles empty input.\n"), patch: "diff --git a/x b/x\n" },
    ]);
    expect(text).toBe(
      [
        `From ${"a".repeat(40)} Mon Sep 17 00:00:00 2001`,
        "From: Ada Lovelace <ada@example.com>",
        "Date: Mon, 12 Oct 2026 08:30:00 +0000",
        "Subject: [PATCH] Fix parser",
        "",
        "Handles empty input.",
        "---",
        "diff --git a/x b/x",
        "-- ",
        "gitfor",
        "",
      ].join("\n"),
    );
  });

  test("series are numbered and subjects without bodies go straight to the diff", () => {
    const text = formatPatchSeries([
      { commit: commit("a".repeat(40), "One"), patch: "diff one" },
      { commit: commit("b".repeat(40), "Two"), patch: "diff two\n" },
    ]);
    expect(text).toContain("Subject: [PATCH 1/2] One\n\n---\ndiff one\n");
    expect(text).toContain("Subject: [PATCH 2/2] Two\n\n---\ndiff two\n");
  });
});