revdiff.ts

import { spawn, spawnSync } from "node:child_process";
import fs from "node:fs";
import os from "node:os";
import path from "node:path";
import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";

type RevdiffResult = { status: "complete"; content: string } | { status: "failed"; exitCode: number | null };

function splitArgs(input: string): string[] {
	const args: string[] = [];
	const re = /"([^"]*)"|'([^']*)'|(\S+)/g;
	let match: RegExpExecArray | null;
	while ((match = re.exec(input)) !== null) {
		args.push(match[1] ?? match[2] ?? match[3]);
	}
	return args;
}

function defaultArgs(cwd: string): string[] {
	const status = spawnSync("git", ["status", "--porcelain"], { cwd, encoding: "utf-8" });
	if (status.status === 0 && status.stdout.trim() === "") {
		return ["HEAD~1", "HEAD"];
	}
	return ["HEAD", "--untracked"];
}

async function runRevdiff(args: string[], cwd: string): Promise<RevdiffResult> {
	const directory = fs.mkdtempSync(path.join(os.tmpdir(), "pi-revdiff-"));
	const outputPath = path.join(directory, "annotations.md");
	try {
		const exitCode = await new Promise<number | null>((resolve) => {
			const child = spawn("revdiff", [...args, "-o", outputPath], {
				cwd,
				stdio: "inherit",
				env: process.env,
			});
			child.on("error", () => resolve(null));
			child.on("close", (code) => resolve(code));
		});

		if (exitCode !== 0 && exitCode !== 10) {
			return { status: "failed", exitCode };
		}

		if (!fs.existsSync(outputPath)) {
			return { status: "complete", content: "" };
		}
		return { status: "complete", content: fs.readFileSync(outputPath, "utf-8").replace(/\n$/, "") };
	} finally {
		try {
			fs.rmSync(directory, { recursive: true, force: true });
		} catch {}
	}
}

export default function (pi: ExtensionAPI) {
	pi.registerCommand("revdiff", {
		description: "Review changes in revdiff; annotations go into the prompt",
		handler: async (args, ctx) => {
			if (ctx.mode !== "tui") {
				ctx.ui.notify("revdiff requires interactive mode", "error");
				return;
			}

			const result = await ctx.ui.custom<RevdiffResult>((tui, _theme, _kb, done) => {
				tui.stop();
				process.stdout.write("\x1b[2J\x1b[H");
				const revdiffArgs = args.trim() ? splitArgs(args) : defaultArgs(ctx.cwd);
				void runRevdiff(revdiffArgs, ctx.cwd).then(
					(res) => {
						tui.start();
						tui.requestRender(true);
						done(res);
					},
					() => {
						tui.start();
						tui.requestRender(true);
						done({ status: "failed", exitCode: null });
					},
				);
				return { render: () => [], invalidate: () => {} };
			});

			if (result.status === "failed") {
				ctx.ui.notify(
					result.exitCode === null
						? "Failed to launch revdiff (is it installed?)"
						: `revdiff exited with status ${result.exitCode}`,
					"error",
				);
				return;
			}

			if (!result.content.trim()) {
				ctx.ui.notify("revdiff produced no annotations", "info");
				return;
			}

			const existing = ctx.ui.getEditorText();
			ctx.ui.setEditorText(existing.trim() ? `${existing.replace(/\n$/, "")}\n\n${result.content}` : result.content);
			ctx.ui.notify("Loaded revdiff annotations into the editor", "info");
		},
	});
}