import { readFile } from "node:fs/promises";
import path from "node:path";
import { pathToFileURL } from "node:url";
import {
  type ModulePackagePlatform,
  ModulePackageVerificationError,
  verifyModulePackage,
} from "../modules/index.js";

/**
 * `verify-module-package` — verifies an Ekklesia Module Package v1 archive against this platform
 * (ADR 0049), and never installs it.
 *
 *   node core/dist/cli/verify-module-package.js <archive>
 *     [--sha256 <hex> | --sha256-file <file>]   the archive's expected SHA-256
 *     [--extract-to <new directory>]            write the verified module directory there
 *
 * Run from the platform's root (`/opt/ekklesia` in the image), like every operator command: the
 * platform's own versions are read from there. `--extract-to` writes only after every check passed,
 * into a directory that must not exist yet; it is the staging step of an installation, not the
 * installation itself.
 */

class VerifyArgumentsError extends Error {}

const USAGE =
  "Usage: verify-module-package <archive> [--sha256 <hex> | --sha256-file <file>] [--extract-to <new directory>]";

export interface VerifyModulePackageArguments {
  readonly archivePath: string;
  readonly expectedSha256?: string;
  readonly sha256File?: string;
  readonly extractTo?: string;
}

function normalizedDigest(value: string): string {
  const digest = value.trim().toLowerCase();
  if (!/^[0-9a-f]{64}$/u.test(digest)) {
    throw new VerifyArgumentsError("The SHA-256 must be 64 hexadecimal characters.");
  }
  return digest;
}

export function parseVerifyModulePackageArguments(
  argv: readonly string[],
): VerifyModulePackageArguments {
  const positional: string[] = [];
  const options = new Map<string, string>();
  for (let index = 0; index < argv.length; index += 1) {
    const argument = argv[index] ?? "";
    if (argument.startsWith("--")) {
      if (!["--sha256", "--sha256-file", "--extract-to"].includes(argument)) {
        throw new VerifyArgumentsError(USAGE);
      }
      const value = argv[index + 1];
      if (value === undefined || value.startsWith("--") || options.has(argument)) {
        throw new VerifyArgumentsError(USAGE);
      }
      options.set(argument, value);
      index += 1;
    } else {
      positional.push(argument);
    }
  }
  const archivePath = positional[0];
  if (positional.length !== 1 || archivePath === undefined || archivePath === "") {
    throw new VerifyArgumentsError(USAGE);
  }
  if (options.has("--sha256") && options.has("--sha256-file")) {
    throw new VerifyArgumentsError(USAGE);
  }
  const sha256 = options.get("--sha256");
  const sha256File = options.get("--sha256-file");
  const extractTo = options.get("--extract-to");
  return {
    archivePath,
    ...(sha256 === undefined ? {} : { expectedSha256: normalizedDigest(sha256) }),
    ...(sha256File === undefined ? {} : { sha256File }),
    ...(extractTo === undefined ? {} : { extractTo }),
  };
}

/** The `sha256sum` format: one line, the digest, whitespace, and a file name that is never trusted. */
export function parseSha256File(contents: string): string {
  const lines = contents.split("\n").filter((line) => line.trim() !== "");
  const match = lines.length === 1 ? /^([0-9a-fA-F]{64})\s+\*?\S/u.exec(lines[0] ?? "") : null;
  if (!match?.[1]) {
    throw new VerifyArgumentsError("The SHA-256 file must hold one sha256sum line.");
  }
  return match[1].toLowerCase();
}

async function readJson(file: string): Promise<Record<string, unknown>> {
  return JSON.parse(await readFile(file, "utf8")) as Record<string, unknown>;
}

function requiredString(value: unknown): string {
  if (typeof value !== "string" || value === "") {
    throw new VerifyArgumentsError("The platform's own package metadata could not be read.");
  }
  return value;
}

/** What this platform is, read from where it is installed. The transitional database runtime is
 * the Drizzle version Core itself depends on (ADR 0049). */
export async function readModulePackagePlatform(
  repositoryRoot: string,
): Promise<ModulePackagePlatform> {
  const [root, sdk, core] = await Promise.all([
    readJson(path.join(repositoryRoot, "package.json")),
    readJson(path.join(repositoryRoot, "packages", "module-sdk", "package.json")),
    readJson(path.join(repositoryRoot, "core", "package.json")),
  ]);
  const dependencies = core.dependencies as Record<string, unknown> | undefined;
  return {
    databaseRuntime: { "drizzle-orm": requiredString(dependencies?.["drizzle-orm"]) },
    moduleSdkVersion: requiredString(sdk.version),
    platformVersion: requiredString(root.version),
  };
}

async function main(): Promise<void> {
  const parsed = parseVerifyModulePackageArguments(process.argv.slice(2));
  let expectedSha256 = parsed.expectedSha256;
  if (parsed.sha256File !== undefined) {
    let contents: string;
    try {
      contents = await readFile(parsed.sha256File, "utf8");
    } catch {
      throw new VerifyArgumentsError("The SHA-256 file could not be read.");
    }
    expectedSha256 = parseSha256File(contents);
  }
  const platform = await readModulePackagePlatform(process.cwd()).catch(() => {
    throw new VerifyArgumentsError("The platform's own package metadata could not be read.");
  });
  const result = await verifyModulePackage({
    archivePath: parsed.archivePath,
    platform,
    ...(expectedSha256 === undefined ? {} : { expectedSha256 }),
    ...(parsed.extractTo === undefined ? {} : { extractTo: parsed.extractTo }),
  });
  console.log(
    `Module package verified: ${result.moduleId}@${result.version} (target ${result.target}), ${result.fileCount} files, sha256 ${result.archiveSha256}.`,
  );
  if (expectedSha256 === undefined) {
    console.log("The archive's SHA-256 was not checked: no expected digest was given.");
  }
  if (parsed.extractTo !== undefined) {
    console.log("The verified module directory was extracted. Nothing was installed.");
  }
}

function isDirectExecution(): boolean {
  const entrypoint = process.argv[1];
  return (
    entrypoint !== undefined && import.meta.url === pathToFileURL(path.resolve(entrypoint)).href
  );
}

if (isDirectExecution()) {
  main().catch((error: unknown) => {
    if (error instanceof ModulePackageVerificationError) {
      console.error(`[${error.code}] ${error.message}`);
      if (error.issueCodes.length > 0) {
        console.error(`Module validation issues: ${error.issueCodes.join(", ")}`);
      }
    } else if (error instanceof VerifyArgumentsError) {
      console.error(error.message);
    } else {
      console.error("Module package verification failed unexpectedly.");
    }
    process.exitCode = 1;
  });
}