/**
 * Local review has no forge to post comments to, so drafted comments are
 * written to a markdown file instead — easy to paste into a PR/MR description,
 * a commit message, or hand to whoever opens the actual pull request.
 */
import { mkdir, writeFile } from "node:fs/promises";
import { join } from "node:path";
import type { DraftComment } from "./state.ts";

function sanitize(name: string): string {
	return name.replace(/[^a-zA-Z0-9._-]+/g, "-").replace(/^-+|-+$/g, "") || "review";
}

export async function writeNotesFile(repoRoot: string, branch: string, drafts: DraftComment[]): Promise<string> {
	const dir = join(repoRoot, ".pi-diff");
	await mkdir(dir, { recursive: true });
	const path = join(dir, `${sanitize(branch)}.md`);

	const byPath = new Map<string, DraftComment[]>();
	for (const draft of drafts) {
		const list = byPath.get(draft.path) ?? [];
		list.push(draft);
		byPath.set(draft.path, list);
	}

	const lines: string[] = [`# Diff notes — ${branch}`, "", `_${drafts.length} comment${drafts.length === 1 ? "" : "s"}, generated by pi-diff_`, ""];
	for (const [path, items] of byPath) {
		lines.push(`## ${path}`, "");
		for (const item of items.sort((a, b) => a.line - b.line)) {
			lines.push(`- **line ${item.line}:** ${item.body}`);
		}
		lines.push("");
	}

	await writeFile(path, lines.join("\n"), "utf8");
	return path;
}