import { execFile } from "node:child_process";
import { promisify } from "node:util";

const execFileAsync = promisify(execFile);
const GIT_COMMAND_TIMEOUT_MS = 2_000;

export type GitStatusSummary = {
	branch?: string;
	dirty: boolean;
	ahead: number;
	behind: number;
	conflicted: number;
	untracked: number;
	stashed: boolean;
	modified: number;
	staged: number;
	renamed: number;
	deleted: number;
	typechanged: number;
};

export function emptyGitStatus(): GitStatusSummary {
	return {
		branch: undefined,
		dirty: false,
		ahead: 0,
		behind: 0,
		conflicted: 0,
		untracked: 0,
		stashed: false,
		modified: 0,
		staged: 0,
		renamed: 0,
		deleted: 0,
		typechanged: 0,
	};
}

export function parseGitStatusPorcelain(stdoutText: string, hasStash: boolean): GitStatusSummary {
	const status = emptyGitStatus();
	status.stashed = hasStash;

	for (const line of stdoutText.split(/\r?\n/)) {
		if (!line) continue;
		if (line.startsWith("# branch.head ")) {
			const branch = line.slice("# branch.head ".length).trim();
			status.branch = branch && branch !== "(detached)" ? branch : undefined;
			continue;
		}
		if (line.startsWith("# branch.ab ")) {
			const match = line.match(/\+(\d+)\s+-(\d+)/);
			if (match) {
				status.ahead = Number(match[1] ?? 0);
				status.behind = Number(match[2] ?? 0);
			}
			continue;
		}
		if (line.startsWith("#")) continue;

		status.dirty = true;

		if (line.startsWith("? ")) {
			status.untracked += 1;
			continue;
		}
		if (line.startsWith("u ")) {
			status.conflicted += 1;
			continue;
		}
		if (!(line.startsWith("1 ") || line.startsWith("2 "))) continue;

		const xy = line.split(" ")[1] ?? "..";
		const x = xy[0] ?? ".";
		const y = xy[1] ?? ".";

		if (x === "R") status.renamed += 1;
		else if (x === "D") status.deleted += 1;
		else if (x === "T") status.typechanged += 1;
		else if (x !== "." && x !== " ") status.staged += 1;

		if (y === "M") status.modified += 1;
		else if (y === "D") status.deleted += 1;
		else if (y === "T") status.typechanged += 1;
	}

	return status;
}

export async function readGitStatus(cwd: string): Promise<GitStatusSummary> {
	try {
		const [{ stdout: statusStdout }, stashResult] = await Promise.all([
			execFileAsync("git", ["status", "--porcelain=2", "--branch"], {
				cwd,
				timeout: GIT_COMMAND_TIMEOUT_MS,
			}),
			execFileAsync("git", ["rev-parse", "--verify", "--quiet", "refs/stash"], {
				cwd,
				timeout: GIT_COMMAND_TIMEOUT_MS,
			}).catch(() => ({ stdout: "" })),
		]);
		const stdoutText = typeof statusStdout === "string" ? statusStdout : String(statusStdout);
		const stashStdout =
			typeof stashResult.stdout === "string" ? stashResult.stdout : String(stashResult.stdout);
		return parseGitStatusPorcelain(stdoutText, stashStdout.trim().length > 0);
	} catch {
		return emptyGitStatus();
	}
}