import path from "node:path";
import { pathToFileURL } from "node:url";
import {
  createAuthorizationEvaluator,
  createAuthorizationStore,
} from "@ekklesia/core/authorization";
import { createIdentityRuntime, type IdentityRateLimitOverride } from "@ekklesia/core/identity";
import { serve, type ServerType } from "@hono/node-server";
import type { Hono } from "hono";
import { createApiApp } from "./app.js";
import { type ApiRuntimeConfig, createApiRuntimeConfig } from "./config.js";
import { type ApiDatabaseHandle, createApiDatabase } from "./database.js";

const connectionTimeoutMs = 10_000;
const operationTimeoutMs = 10_000;

export interface RunningApi {
  readonly app: Hono;
  readonly server: ServerType;
  shutdown(): Promise<void>;
}

export interface StartApiOptions {
  /** Test-only escape hatch: never set by the executable entry point. See
   * `IdentityRateLimitOverride` for why production must leave this unset. */
  readonly rateLimitOverride?: IdentityRateLimitOverride;
}

async function safeCloseDatabase(handle: ApiDatabaseHandle): Promise<void> {
  try {
    await handle.close();
  } catch {
    // Cleanup failures are swallowed here deliberately: they must never mask a startup failure
    // that is already propagating, and there is no raw driver detail safe to surface.
  }
}

function bindServer(app: Hono, host: string, port: number): Promise<ServerType> {
  return new Promise((resolve, reject) => {
    let settled = false;
    const server = serve({ fetch: app.fetch, hostname: host, port }, () => {
      if (!settled) {
        settled = true;
        resolve(server);
      }
    });
    server.once("error", () => {
      if (!settled) {
        settled = true;
        reject(new Error("The API server failed to start listening."));
      }
    });
  });
}

/**
 * Explicit runtime composition: constructs the one shared PostgreSQL pool (identity and
 * authorization each get a typed Drizzle view over it — see `./database.js`), the Core identity
 * runtime, the Core authorization store and evaluator, and the Hono application, then starts the
 * Node HTTP server. Returns a handle with an idempotent `shutdown()` so both the executable entry
 * point and tests can stop the server and close the shared pool deterministically. Never applies
 * migrations or generates schema — the database must already be migrated through
 * `pnpm migrations:apply`.
 */
export async function startApi(
  config: ApiRuntimeConfig,
  options: StartApiOptions = {},
): Promise<RunningApi> {
  const databaseHandle = createApiDatabase(config.databaseUrl, {
    connectionTimeoutMs,
    operationTimeoutMs,
  });

  let runtime: ReturnType<typeof createIdentityRuntime>;
  let authorizationStore: ReturnType<typeof createAuthorizationStore>;
  try {
    runtime = createIdentityRuntime({
      config: config.identity,
      db: databaseHandle.identity,
      ...(options.rateLimitOverride ? { rateLimitOverride: options.rateLimitOverride } : {}),
    });
    authorizationStore = createAuthorizationStore(databaseHandle.authorization);
  } catch (error) {
    await safeCloseDatabase(databaseHandle);
    throw error;
  }

  const evaluator = createAuthorizationEvaluator({
    grants: authorizationStore,
    platformOwners: authorizationStore,
  });

  const app = createApiApp({
    authorization: { evaluator, store: authorizationStore },
    runtime,
    trustedOrigins: config.identity.trustedOrigins,
  });

  let server: ServerType;
  try {
    server = await bindServer(app, config.host, config.port);
  } catch (error) {
    await safeCloseDatabase(databaseHandle);
    throw error;
  }

  // Memoizes one shared promise rather than a boolean flag: a boolean only prevents a *second*
  // cleanup from starting, but a caller that arrives while the first cleanup is still in flight
  // would previously get an already-resolved `undefined` immediately, before the listener had
  // actually drained or the pool had actually closed. Storing the promise itself means every
  // caller — concurrent or sequential — awaits the exact same drain-then-close operation and
  // observes it complete (or fail) exactly once.
  let shutdownPromise: Promise<void> | undefined;
  const shutdown = (): Promise<void> => {
    if (!shutdownPromise) {
      shutdownPromise = (async () => {
        await new Promise<void>((resolve) => {
          server.close(() => resolve());
        });
        await safeCloseDatabase(databaseHandle);
      })();
    }
    return shutdownPromise;
  };

  return Object.freeze({ app, server, shutdown });
}

/**
 * Wires `SIGINT`/`SIGTERM` to `running.shutdown()` and only then exits — extracted from `main()`
 * so it can be exercised directly in tests with a fake `running`/`exit`, without sending a real
 * process signal or invoking the real `process.exit` (which would terminate the test runner
 * itself). Production composition (`main()`, below) calls this with real `process.exit`.
 */
export function installShutdownSignalHandlers(
  running: Pick<RunningApi, "shutdown">,
  exit: (code: number) => void = (code) => process.exit(code),
): void {
  let signalReceived = false;
  const handleSignal = (): void => {
    if (signalReceived) {
      return;
    }
    signalReceived = true;
    running
      .shutdown()
      .then(() => exit(0))
      .catch(() => exit(1));
  };
  process.on("SIGINT", handleSignal);
  process.on("SIGTERM", handleSignal);
}

function readConfigFromEnvironment(): {
  readonly input: Parameters<typeof createApiRuntimeConfig>[0];
  readonly environment: "development" | "production";
} {
  const trustedOriginsValue = process.env.EKKLESIA_IDENTITY_TRUSTED_ORIGINS;
  const trustedOrigins = trustedOriginsValue
    ?.split(",")
    .map((origin) => origin.trim())
    .filter((origin) => origin.length > 0);

  return {
    environment: process.env.NODE_ENV === "development" ? "development" : "production",
    input: {
      databaseUrl: process.env.DATABASE_URL,
      host: process.env.EKKLESIA_API_HOST,
      identity: {
        baseUrl: process.env.EKKLESIA_IDENTITY_BASE_URL,
        secret: process.env.EKKLESIA_IDENTITY_SECRET,
        trustedOrigins,
      },
      port: process.env.EKKLESIA_API_PORT,
    },
  };
}

export async function main(): Promise<void> {
  const { environment, input } = readConfigFromEnvironment();
  const config = createApiRuntimeConfig(input, { environment });
  const running = await startApi(config);

  const address = running.server.address();
  const boundPort = address && typeof address === "object" ? address.port : config.port;
  console.log(`Ekklesia API listening on ${config.host}:${boundPort}`);

  installShutdownSignalHandlers(running);
}

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

if (isDirectExecution()) {
  main().catch(() => {
    console.error("Ekklesia API failed to start.");
    process.exitCode = 1;
  });
}