import assert from "node:assert/strict";
import { execFileSync } from "node:child_process";
import { existsSync } from "node:fs";
import { mkdir, mkdtemp, realpath, readFile, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import test from "node:test";

import { createGit, GitError } from "../src/git.ts";

const git = createGit();

const GIT_ENV = {
	...process.env,
	GIT_AUTHOR_NAME: "pi-worktree-test",
	GIT_AUTHOR_EMAIL: "test@example.com",
	GIT_COMMITTER_NAME: "pi-worktree-test",
	GIT_COMMITTER_EMAIL: "test@example.com",
};

function raw(args: string[], cwd: string): string {
	return execFileSync("git", args, { cwd, env: GIT_ENV, encoding: "utf8" });
}

/** Creates <tmp>/repo as a git repo; sibling dirs under <tmp> host worktrees. */
async function makeRepo(): Promise<{ parent: string; repo: string }> {
	const parent = await mkdtemp(join(tmpdir(), "pi-worktree-git-"));
	const repo = join(parent, "repo");
	await mkdir(repo);
	raw(["init", "-b", "main"], repo);
	raw(["config", "user.name", "pi-worktree-test"], repo);
	raw(["config", "user.email", "test@example.com"], repo);
	await writeFile(join(repo, "file.txt"), "base\n", "utf8");
	raw(["add", "-A"], repo);
	raw(["commit", "-m", "init"], repo);
	return { parent, repo };
}

async function commitFile(dir: string, name: string, content: string, message: string): Promise<void> {
	await writeFile(join(dir, name), content, "utf8");
	raw(["add", "-A"], dir);
	raw(["commit", "-m", message], dir);
}

async function worktreeOf(parent: string, repo: string, name: string): Promise<string> {
	const path = join(parent, name);
	await git.addWorktree(repo, path, `wt/${name}`, "HEAD");
	return path;
}

test("addWorktree creates the directory and branch", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-a");
	assert.ok(existsSync(wt));
	assert.equal(await git.getCurrentBranch(wt), "wt/feat-a");
	assert.ok(await git.branchExists(repo, "wt/feat-a"));
});

test("ff-only merge brings source HEAD to the worktree HEAD", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-b");
	await commitFile(wt, "new.txt", "work\n", "wt commit");

	const rebaseResult = await git.rebase(wt, "main");
	assert.deepEqual(rebaseResult, { ok: true, conflict: false });
	assert.equal(await git.aheadCount(wt, "main", "wt/feat-b"), 1);

	await git.mergeFfOnly(repo, "wt/feat-b");
	assert.equal(await git.getHeadSha(repo), await git.getHeadSha(wt));
});

test("rebase conflict stays in progress, lists unmerged files, and aborts cleanly", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-c");
	await commitFile(wt, "file.txt", "worktree version\n", "wt edit");
	await commitFile(repo, "file.txt", "source version\n", "source edit");

	const before = await git.getHeadSha(wt);
	const result = await git.rebase(wt, "main");
	assert.deepEqual(result, { ok: false, conflict: true });
	assert.equal(await git.rebaseInProgress(wt), true);
	assert.deepEqual(await git.unmergedFiles(wt), ["file.txt"]);

	await git.rebaseAbort(wt);
	assert.equal(await git.rebaseInProgress(wt), false);
	assert.equal(await git.getHeadSha(wt), before);
	assert.ok(!(await git.isDirty(wt)));
});

test("rebaseContinue finishes once conflicts are resolved and added", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-c2");
	await commitFile(wt, "file.txt", "worktree version\n", "wt edit");
	await commitFile(repo, "file.txt", "source version\n", "source edit");

	const result = await git.rebase(wt, "main");
	assert.deepEqual(result, { ok: false, conflict: true });
	assert.equal(await git.rebaseInProgress(wt), true);

	await writeFile(join(wt, "file.txt"), "resolved\n", "utf8");
	raw(["add", "file.txt"], wt);
	const continued = await git.rebaseContinue(wt);
	assert.deepEqual(continued, { ok: true, conflict: false });
	assert.equal(await git.rebaseInProgress(wt), false);
	assert.equal(await git.isAncestor(repo, "main", "wt/feat-c2"), true);
});

test("mergeSquash produces exactly one new commit on the source", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-d");
	await commitFile(wt, "a.txt", "1\n", "c1");
	await commitFile(wt, "b.txt", "2\n", "c2");

	const before = await git.getHeadSha(repo);
	await git.rebase(wt, "main");
	await git.mergeSquash(repo, "wt/feat-d", "squashed");
	const after = await git.getHeadSha(repo);
	assert.notEqual(before, after);
	assert.equal(raw(["rev-list", "--count", `${before}..${after}`], repo).trim(), "1");
	assert.equal(await readFile(join(repo, "a.txt"), "utf8"), "1\n");
});

test("stashPush reports whether anything was stashed and stashPop restores it", async () => {
	const { repo } = await makeRepo();
	assert.equal(await git.stashPush(repo, "nothing"), false);
	await writeFile(join(repo, "dirty.txt"), "dirty\n", "utf8");
	assert.equal(await git.stashPush(repo, "pi-worktree test"), true);
	assert.equal(existsSync(join(repo, "dirty.txt")), false);
	await git.stashPop(repo);
	assert.equal(await readFile(join(repo, "dirty.txt"), "utf8"), "dirty\n");
});

test("rebase onto a nonexistent ref throws the original rebase error", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-e");
	await assert.rejects(
		() => git.rebase(wt, "no-such-ref"),
		(error: unknown) => {
			assert.ok(error instanceof GitError, `expected GitError, got ${String(error)}`);
			assert.equal(error.args[0], "rebase");
			assert.ok(!error.message.includes("--abort"), error.message);
			return true;
		},
	);
	assert.equal(await git.rebaseInProgress(wt), false);
});

test("removeWorktree with force deletes the directory while the branch stays", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-f");
	await writeFile(join(wt, "junk.bin"), "x", "utf8");
	await git.removeWorktree(repo, wt, true);
	assert.equal(existsSync(wt), false);
	assert.ok(await git.branchExists(repo, "wt/feat-f"));
});

test("listWorktrees parses main, linked, and detached entries", async () => {
	const { parent, repo } = await makeRepo();
	const wt = await worktreeOf(parent, repo, "feat-g");
	const detachedPath = join(parent, "detached-wt");
	raw(["worktree", "add", "--detach", detachedPath, "HEAD"], repo);

	const entries = await git.listWorktrees(repo);
	assert.equal(entries.length, 3);
	const byPath = new Map(
		await Promise.all(
			entries.map(async (e) => [(await realpath(e.path).catch(() => e.path)), e] as const),
		),
	);
	const main = entries[0];
	assert.equal(main?.branch, "main");
	assert.equal(byPath.get(await realpath(wt))?.branch, "wt/feat-g");
	assert.equal(byPath.get(await realpath(detachedPath))?.detached, true);
	assert.equal(await git.getMainWorktreePath(repo), main?.path);
});