import * as Data from "effect/Data";
import * as Effect from "effect/Effect";
import * as ChildProcess from "effect/unstable/process/ChildProcess";
import * as ChildProcessSpawner from "effect/unstable/process/ChildProcessSpawner";
import { fileURLToPath } from "node:url";

export class RunnerError extends Data.TaggedError<"RunnerError">("RunnerError")<{
  readonly message: string;
  readonly cause?: unknown;
}> {}

/**
 * The JSON configuration passed to `runner.mjs` (as `process.argv[2]`).
 * Mirrors the shape the runner script parses.
 */
export interface RunnerConfig {
  /** The Next.js app root (the directory containing `open-next.config.ts`). */
  readonly appDir: string;
  /** Path of the OpenNext config, relative to `appDir`. @default "open-next.config.ts" */
  readonly configPath?: string | undefined;
  /** `compatibility_date` of the in-memory wrangler-config stand-in. */
  readonly compatibilityDate: string;
  /** Skip the internal `next build` (reuse an existing `.next`). @default false */
  readonly skipNextBuild?: boolean | undefined;
  /** Minify the OpenNext bundling steps. @default false */
  readonly minify?: boolean | undefined;
  /** Enable OpenNext debug logging. @default false */
  readonly debug?: boolean | undefined;
  /**
   * The command the pipeline runs to build the Next.js app. Defaults (in the
   * runner) to `npx next build` — NOT the app's `build` script, which by
   * fixture convention is `e2e build` and would recurse into this runner.
   */
  readonly buildCommand?: string | undefined;
}

/** Absolute path of the runner script (`runner.mjs` sibling of this module). */
export const runnerPath = (): string => fileURLToPath(new URL("./runner.mjs", import.meta.url));

/**
 * Run the programmatic `@opennextjs/cloudflare` build pipeline in a
 * disposable `node` child process (`runner.mjs`). The pipeline mutates
 * cwd-coupled module state, spawns `next build`, and can `process.exit(1)`,
 * so it must never run inside the calling process.
 *
 * Output is inherited so `next build` progress streams through.
 */
export const runOpenNextBuild = (
  config: RunnerConfig,
): Effect.Effect<void, RunnerError, ChildProcessSpawner.ChildProcessSpawner> =>
  Effect.gen(function* () {
    const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
    const command = ChildProcess.make("node", [runnerPath(), JSON.stringify(config)], {
      cwd: config.appDir,
      stdin: "ignore",
      stdout: "inherit",
      stderr: "inherit",
    });
    const exitCode = yield* spawner.exitCode(command).pipe(
      Effect.mapError(
        (cause) =>
          new RunnerError({
            message: "Failed to spawn the OpenNext build runner (is `node` on PATH?)",
            cause,
          }),
      ),
    );
    if (exitCode !== 0) {
      return yield* new RunnerError({
        message: `The OpenNext build pipeline exited with code ${exitCode}`,
      });
    }
  });