import { beforeAll, describe, expect, test } from "bun:test";
import { writeFile } from "node:fs/promises";
import { join } from "node:path";
import { openBucket } from "../src/bucket/reader.ts";
import { checkFormat, listRepos, readHead, readObject, readSave } from "../src/bucket/repo.ts";
import { type Fixture, makeKohBucket } from "./fixture.ts";

let fx: Fixture;
beforeAll(async () => {
	fx = await makeKohBucket();
});

const bucket = () => openBucket({ kind: "folder", path: fx.bucketDir });

describe("reading a koh3-produced folder remote", () => {
	test("lists the repo", async () => {
		expect(await listRepos(bucket())).toEqual([fx.repo]);
	});

	test("reads format, head, the save record and one verified object end to end", async () => {
		const b = bucket();
		await checkFormat(b, fx.repo);
		const head = await readHead(b, fx.repo);
		expect(head).toBe(fx.saveIds[0] as string);

		const save = await readSave(b, fx.repo, head as string);
		expect(save.message).toBe("say hello");
		expect(save.is_checkpoint).toBe(false);
		const checkpoint = await readSave(b, fx.repo, save.parent);
		expect(checkpoint.is_checkpoint).toBe(true);
		const first = await readSave(b, fx.repo, checkpoint.parent);
		expect([first.agent, first.session]).toEqual(["test-agent", "fixture"]);

		const main = save.files.find((file) => file.path === "src/main.ts");
		const bytes = await readObject(b, fx.repo, main?.hash as string);
		expect(new TextDecoder().decode(bytes)).toBe("// Entry point.\nconsole.log('hello');\n");
	});

	test("a missing key reads as null and a listing is prefix-scoped", async () => {
		const b = bucket();
		expect(await b.get(`${fx.repo}/nothing-here`)).toBeNull();
		const saves = await b.list(`${fx.repo}/saves/`);
		expect(saves.sort()).toEqual(fx.saveIds.map((id) => `${fx.repo}/saves/${id}`).sort());
	});
});

test("the S3 reader pages through listings and reads a missing key as null", async () => {
	const pageSize = 2;
	const server = Bun.serve({
		port: 0,
		async fetch(req) {
			const url = new URL(req.url);
			const folder = bucket();
			if (url.searchParams.get("list-type") === "2") {
				const all = await folder.list(url.searchParams.get("prefix") ?? "");
				const start = Number(url.searchParams.get("continuation-token") ?? 0);
				const page = all.slice(start, start + pageSize);
				const more = start + pageSize < all.length;
				const contents = page.map((key) => `<Contents><Key>${key}</Key></Contents>`).join("");
				const next = more
					? `<NextContinuationToken>${start + pageSize}</NextContinuationToken>`
					: "";
				return new Response(
					`<ListBucketResult><IsTruncated>${more}</IsTruncated>${contents}${next}</ListBucketResult>`,
				);
			}
			const bytes = await folder.get(url.pathname.replace("/kohbucket/", ""));
			if (bytes) return new Response(bytes);
			return new Response("<Error><Code>NoSuchKey</Code></Error>", { status: 404 });
		},
	});
	try {
		const s3 = openBucket({
			kind: "s3",
			endpoint: `http://localhost:${server.port}`,
			name: "kohbucket",
			region: "fr-par",
			accessKeyId: "read",
			secretAccessKey: "only",
		});
		expect(await s3.list(`${fx.repo}/`)).toEqual(await bucket().list(`${fx.repo}/`));
		expect(await readHead(s3, fx.repo)).toBe(fx.saveIds[0] as string);
		expect(await s3.get(`${fx.repo}/format`)).toBeNull();
	} finally {
		server.stop();
	}
});

describe("the format rule", () => {
	test("accepts koh-remote 1 and refuses anything else", async () => {
		const { bucketDir, repo } = await makeKohBucket("formatted");
		const b = openBucket({ kind: "folder", path: bucketDir });
		await writeFile(join(bucketDir, repo, "format"), "koh-remote 1");
		await checkFormat(b, repo);
		await writeFile(join(bucketDir, repo, "format"), "koh-remote 2");
		await expect(checkFormat(b, repo)).rejects.toThrow('remote format "koh-remote 2"');
	});
});

describe("object verification", () => {
	test("refuses an object whose content does not match its key", async () => {
		const b = bucket();
		const save = await readSave(b, fx.repo, fx.saveIds[0] as string);
		const [one, two] = save.files;
		const swapped = {
			...b,
			get: (key: string) => b.get(key.replace(one?.hash ?? "", two?.hash ?? "")),
		};
		await expect(readObject(swapped, fx.repo, one?.hash as string)).rejects.toThrow(
			"does not match its hash",
		);
	});
});

describe("untrusted input", () => {
	// Starts from a genuine koh3 record and corrupts one field, as a tampered bucket would.
	async function readTampered(change: (record: Record<string, unknown>) => void) {
		const id = fx.saveIds[0] as string;
		const real = await bucket().get(`${fx.repo}/saves/${id}`);
		const record = JSON.parse(new TextDecoder().decode(real as Uint8Array));
		change(record);
		const bytes = new TextEncoder().encode(JSON.stringify(record));
		return readSave({ get: async () => bytes, list: async () => [] }, fx.repo, id);
	}
	const withPath = (path: string) => (record: Record<string, unknown>) => {
		(record.files as { path: string }[])[0] = { ...(record.files as { path: string }[])[0], path };
	};

	test("the genuine record is accepted", async () => {
		expect((await readTampered(() => {})).message).toBe("say hello");
	});

	test.each([
		"",
		"/etc/passwd",
		"../escape",
		"src/../../escape",
		"./src/main.ts",
		"src//main.ts",
		"src/",
		"src\\main.ts",
		"src/ma\0in.ts",
		"src/ma\nin.ts",
	])("refuses the file path %p", async (path) => {
		await expect(readTampered(withPath(path))).rejects.toThrow("Koh 3 schema");
	});

	test("refuses duplicate paths in one record", async () => {
		const dupe = (record: Record<string, unknown>) => {
			const files = record.files as { path: string }[];
			files[1] = { ...files[1], path: (files[0] as { path: string }).path } as { path: string };
		};
		await expect(readTampered(dupe)).rejects.toThrow("Koh 3 schema");
	});

	test.each([
		["parent", "not-an-id"],
		["restores", "ABCDEF123456"],
		["replayed_from", "../../../x"],
		["created_at", -1],
		["created_at", 1.5],
		["size_bytes", -10],
		["size_bytes", "12"],
	])("refuses %s = %p", async (field, value) => {
		await expect(readTampered((record) => (record[field] = value))).rejects.toThrow("Koh 3 schema");
	});

	test("refuses bad repo names and save IDs before building a key", async () => {
		const b = bucket();
		for (const repo of ["..", "a/b", "", "../demo"]) {
			await expect(checkFormat(b, repo)).rejects.toThrow("not a repo name");
			await expect(readHead(b, repo)).rejects.toThrow("not a repo name");
			await expect(readSave(b, repo, fx.saveIds[0] as string)).rejects.toThrow("not a repo name");
			await expect(readObject(b, repo, "0".repeat(64))).rejects.toThrow("not a repo name");
		}
		for (const id of ["../head", "abc", "ABCDEF123456", `${fx.saveIds[0]}0`]) {
			await expect(readSave(b, fx.repo, id)).rejects.toThrow("not a save ID");
		}
	});
});