import { promises as fs } from "node:fs";
import * as os from "node:os";
import * as path from "node:path";
import type { ScopedInstruction } from "./instructions.ts";
import type { PullRequestSnapshot } from "./types.ts";

export interface SnapshotFiles {
	directory: string;
	manifestPath: string;
	dispose(): Promise<void>;
}

export async function writeSnapshot(
	snapshot: PullRequestSnapshot,
	instructions: ScopedInstruction[],
): Promise<SnapshotFiles> {
	const directory = await fs.mkdtemp(path.join(os.tmpdir(), "pi-code-review-"));
	await fs.chmod(directory, 0o700);
	const metadataPath = path.join(directory, "pull-request.json");
	const diffPath = path.join(directory, "changes.diff");
	const instructionsPath = path.join(directory, "instructions.json");
	const manifestPath = path.join(directory, "manifest.json");
	const writePrivate = async (filePath: string, content: string) => {
		await fs.writeFile(filePath, content, { encoding: "utf8", mode: 0o600 });
	};
	await writePrivate(
		metadataPath,
		JSON.stringify({ ...snapshot, diff: undefined }, null, 2),
	);
	await writePrivate(diffPath, snapshot.diff);
	await writePrivate(instructionsPath, JSON.stringify(instructions, null, 2));
	await writePrivate(
		manifestPath,
		JSON.stringify(
			{
				metadata: metadataPath,
				diff: diffPath,
				instructions: instructionsPath,
				changedFiles: snapshot.files.map((file) => file.path),
			},
			null,
			2,
		),
	);
	let disposed = false;
	return {
		directory,
		manifestPath,
		async dispose() {
			if (disposed) return;
			disposed = true;
			await fs.rm(directory, { recursive: true, force: true });
		},
	};
}