import { execFile } from "node:child_process";
import { mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import path from "node:path";
import { promisify } from "node:util";
import { Client } from "pg";
import { afterAll, describe, expect, it } from "vitest";
import { databaseTlsConnectionOptions } from "../src/database/transport.js";

const run = promisify(execFile);

/**
 * Real TLS proof for the production transport policy, exercised through the pinned `pg` client
 * against a disposable, TLS-enabled PostgreSQL container.
 *
 * Every certificate, key, and CA used here is generated at test runtime into an isolated temporary
 * directory and deleted in `afterAll` — no private-key material is committed to this repository.
 * The container, its name, and its published loopback port are likewise disposable and removed in
 * `afterAll` even when an assertion fails.
 */
const containerName = `ekklesia-database-tls-${process.pid}`;
let certificateDirectory: string | undefined;
let containerStarted = false;
let boundPort: number | undefined;

class TlsHarnessError extends Error {
  constructor(message: string) {
    super(message);
    this.name = "TlsHarnessError";
    this.stack = `${this.name}: ${this.message}`;
  }
}

async function openssl(args: readonly string[], cwd: string): Promise<void> {
  try {
    await run("openssl", [...args], { cwd });
  } catch {
    // Never surface openssl's own stderr: it can echo paths from the harness environment.
    throw new TlsHarnessError("The disposable TLS material could not be generated.");
  }
}

/** Generates a private CA, a server certificate signed by it whose only SAN is `DNS:localhost`,
 * and an unrelated second CA. The deliberately narrow SAN is what makes the hostname-mismatch
 * assertion below meaningful: reaching the very same server through `127.0.0.1` must fail. */
async function generateCertificates(directory: string): Promise<void> {
  await openssl(
    [
      "req",
      "-new",
      "-x509",
      "-days",
      "1",
      "-nodes",
      "-out",
      "ca.crt",
      "-keyout",
      "ca.key",
      "-subj",
      "/CN=Ekklesia Disposable Test CA",
    ],
    directory,
  );
  await openssl(
    [
      "req",
      "-new",
      "-nodes",
      "-out",
      "server.csr",
      "-keyout",
      "server.key",
      "-subj",
      "/CN=localhost",
    ],
    directory,
  );
  await writeFile(path.join(directory, "san.cnf"), "subjectAltName=DNS:localhost\n");
  await openssl(
    [
      "x509",
      "-req",
      "-in",
      "server.csr",
      "-CA",
      "ca.crt",
      "-CAkey",
      "ca.key",
      "-CAcreateserial",
      "-out",
      "server.crt",
      "-days",
      "1",
      "-extfile",
      "san.cnf",
    ],
    directory,
  );
  await openssl(
    [
      "req",
      "-new",
      "-x509",
      "-days",
      "1",
      "-nodes",
      "-out",
      "other-ca.crt",
      "-keyout",
      "other-ca.key",
      "-subj",
      "/CN=Unrelated Test CA",
    ],
    directory,
  );
}

async function docker(args: readonly string[]): Promise<string> {
  const { stdout } = await run("docker", [...args]);
  return stdout.trim();
}

async function startTlsPostgres(directory: string): Promise<number> {
  // The certificate/key are copied *inside* the container and re-owned before PostgreSQL starts:
  // PostgreSQL refuses a key file that is not owned by the database user or root, and a bind-
  // mounted host file keeps the host's ownership.
  await docker([
    "run",
    "-d",
    "--name",
    containerName,
    "-e",
    "POSTGRES_DB=ekklesia_tls",
    "-e",
    "POSTGRES_USER=ekklesia_tls",
    "-e",
    "POSTGRES_PASSWORD=ekklesia_tls",
    "-v",
    `${directory}:/certs-src:ro`,
    "-p",
    "127.0.0.1:0:5432",
    "--entrypoint",
    "/bin/sh",
    "postgres:18.4-alpine3.24",
    "-c",
    "mkdir -p /tls && cp /certs-src/server.crt /certs-src/server.key /tls/ && " +
      "chown postgres:postgres /tls/server.* && chmod 600 /tls/server.key && " +
      "exec docker-entrypoint.sh postgres -c ssl=on -c ssl_cert_file=/tls/server.crt " +
      "-c ssl_key_file=/tls/server.key",
  ]);
  containerStarted = true;

  const published = await docker(["port", containerName, "5432"]);
  const match = /^127\.0\.0\.1:(\d+)$/u.exec(published.split("\n")[0]?.trim() ?? "");
  if (!match) {
    throw new TlsHarnessError(
      "The disposable TLS PostgreSQL port is not bound safely to loopback.",
    );
  }
  return Number(match[1]);
}

/** Bounded readiness polling — never an arbitrary sleep. Resolves once the server accepts a TLS
 * connection, or fails after the deadline. */
async function waitForTlsReadiness(port: number, ca: string): Promise<void> {
  const deadline = Date.now() + 60_000;
  let lastError: unknown;
  while (Date.now() < deadline) {
    const client = new Client({
      connectionTimeoutMillis: 3_000,
      database: "ekklesia_tls",
      host: "localhost",
      password: "ekklesia_tls",
      port,
      ssl: { ca, rejectUnauthorized: true },
      user: "ekklesia_tls",
    });
    try {
      await client.connect();
      await client.end();
      return;
    } catch (error) {
      lastError = error;
      try {
        await client.end();
      } catch {
        // The failed client is already unusable; nothing to clean up beyond this.
      }
      await new Promise((resolve) => setTimeout(resolve, 250));
    }
  }
  throw new TlsHarnessError(
    `The disposable TLS PostgreSQL did not become ready: ${String(lastError)}`,
  );
}

async function connectWith(
  host: string,
  port: number,
  ssl: ReturnType<typeof databaseTlsConnectionOptions>,
): Promise<{ encrypted: boolean }> {
  const client = new Client({
    connectionTimeoutMillis: 5_000,
    database: "ekklesia_tls",
    host,
    password: "ekklesia_tls",
    port,
    ...(ssl === false ? {} : { ssl }),
    user: "ekklesia_tls",
  });
  try {
    await client.connect();
    const result = await client.query<{ encrypted: boolean }>(
      "SELECT ssl AS encrypted FROM pg_stat_ssl WHERE pid = pg_backend_pid()",
    );
    return { encrypted: result.rows[0]?.encrypted === true };
  } finally {
    try {
      await client.end();
    } catch {
      // Closing an already-failed client is not itself a test failure.
    }
  }
}

afterAll(async () => {
  if (containerStarted) {
    await docker(["rm", "-f", containerName]).catch(() => undefined);
  }
  if (certificateDirectory) {
    // Removes the generated CA, server certificate, and every private key.
    await rm(certificateDirectory, { force: true, recursive: true }).catch(() => undefined);
  }
});

describe.sequential("production PostgreSQL TLS policy against a real TLS endpoint", () => {
  it("starts a disposable TLS-enabled PostgreSQL with runtime-generated certificates", async () => {
    certificateDirectory = await mkdtemp(path.join(tmpdir(), "ekklesia-tls-"));
    await generateCertificates(certificateDirectory);
    boundPort = await startTlsPostgres(certificateDirectory);
    const ca = await readFile(path.join(certificateDirectory, "ca.crt"), "utf8");
    await waitForTlsReadiness(boundPort, ca);
    expect(boundPort).toBeGreaterThan(0);
  });

  it("connects successfully, and encrypted, when the certificate is trusted and its identity matches the host", async () => {
    const ca = await readFile(path.join(certificateDirectory as string, "ca.crt"), "utf8");
    const ssl = databaseTlsConnectionOptions(
      `postgresql://ekklesia_tls@localhost:${boundPort}/ekklesia_tls`,
      { certificateAuthority: ca, mode: "verify-full" },
    );

    const { encrypted } = await connectWith("localhost", boundPort as number, ssl);
    expect(encrypted).toBe(true);
  });

  it("refuses a certificate that does not chain to the configured CA", async () => {
    const otherCa = await readFile(
      path.join(certificateDirectory as string, "other-ca.crt"),
      "utf8",
    );
    const ssl = databaseTlsConnectionOptions(
      `postgresql://ekklesia_tls@localhost:${boundPort}/ekklesia_tls`,
      { certificateAuthority: otherCa, mode: "verify-full" },
    );

    await expect(connectWith("localhost", boundPort as number, ssl)).rejects.toMatchObject({
      code: "UNABLE_TO_VERIFY_LEAF_SIGNATURE",
    });
  });

  it("refuses a trusted certificate whose identity does not match the host being connected to", async () => {
    // The server certificate's only SAN is `DNS:localhost`, so reaching the identical server via
    // its IP address is a genuine hostname mismatch. This is the case the pinned driver does *not*
    // catch on its own: `pg` sets `servername` only for non-IP hosts, and Node performs no identity
    // check when it is unset, so `rejectUnauthorized: true` alone would accept this connection.
    const ca = await readFile(path.join(certificateDirectory as string, "ca.crt"), "utf8");
    const ssl = databaseTlsConnectionOptions(
      `postgresql://ekklesia_tls@127.0.0.1:${boundPort}/ekklesia_tls`,
      { certificateAuthority: ca, mode: "verify-full" },
    );

    await expect(connectWith("127.0.0.1", boundPort as number, ssl)).rejects.toMatchObject({
      code: "ERR_TLS_CERT_ALTNAME_INVALID",
    });
  });

  it("proves the gap the policy closes: chain-only verification would accept that same mismatch", async () => {
    const ca = await readFile(path.join(certificateDirectory as string, "ca.crt"), "utf8");
    // Exactly what `ssl: { ca, rejectUnauthorized: true }` alone does — no pinned
    // `checkServerIdentity`. It connects, which is why the policy supplies one.
    const { encrypted } = await connectWith("127.0.0.1", boundPort as number, {
      ca,
      rejectUnauthorized: true,
    });
    expect(encrypted).toBe(true);
  });

  it("cannot satisfy verify-full against a plaintext-only PostgreSQL endpoint", async () => {
    // The disposable plaintext PostgreSQL the rest of the integration suite uses.
    const plaintextUrl = process.env.EKKLESIA_MIGRATION_TEST_DATABASE_URL;
    if (typeof plaintextUrl !== "string" || plaintextUrl.trim() === "") {
      throw new TlsHarnessError("The plaintext integration database is not configured.");
    }
    const parsed = new URL(plaintextUrl);
    const ca = await readFile(path.join(certificateDirectory as string, "ca.crt"), "utf8");
    const ssl = databaseTlsConnectionOptions(plaintextUrl, {
      certificateAuthority: ca,
      mode: "verify-full",
    });

    const client = new Client({
      connectionTimeoutMillis: 5_000,
      database: parsed.pathname.slice(1),
      host: parsed.hostname,
      password: decodeURIComponent(parsed.password),
      port: Number(parsed.port),
      ...(ssl === false ? {} : { ssl }),
      user: decodeURIComponent(parsed.username),
    });
    try {
      await expect(client.connect()).rejects.toBeTruthy();
    } finally {
      try {
        await client.end();
      } catch {
        // Already unusable.
      }
    }
  });
});