import { readFile } from "node:fs/promises";
import path from "node:path";
import type { HostEnvironment } from "../host/index.js";
import { discoverAllMigrations } from "../migrations/index.js";
import type { ModuleMigrationAggregate } from "../modules/index.js";
import { resolveCommandModulesDirectory } from "./modules-directory-environment.js";

interface PackageVersion {
  readonly version?: unknown;
}

async function readPackageVersion(packagePath: string): Promise<string> {
  const packageData = JSON.parse(await readFile(packagePath, "utf8")) as PackageVersion;
  if (typeof packageData.version !== "string") {
    throw new TypeError("A required workspace package does not declare a version.");
  }
  return packageData.version;
}

/**
 * Core's migrations come from the platform (`<repositoryRoot>/core/drizzle`); installed modules'
 * come from the configured modules directory, wherever it is (ADR 0048). Neither is ever derived
 * from the other.
 */
export async function discoverRepositoryMigrations(
  repositoryRoot = process.cwd(),
  environment: HostEnvironment = process.env,
): Promise<ModuleMigrationAggregate> {
  const modulesDirectory = resolveCommandModulesDirectory(environment, repositoryRoot);
  const [platformVersion, moduleSdkVersion] = await Promise.all([
    readPackageVersion(path.join(repositoryRoot, "package.json")),
    readPackageVersion(path.join(repositoryRoot, "packages/module-sdk/package.json")),
  ]);

  return discoverAllMigrations({
    coreMigrationsDirectory: path.join(repositoryRoot, "core", "drizzle"),
    moduleDiscovery: {
      moduleSdkVersion,
      ...modulesDirectory,
      platformVersion,
    },
  });
}