/**
 * RuntimeManager.ts — Orchestrates all code execution runtimes
 *
 * Routing strategy:
 *   python/py  → Pyodide Worker via WorkerManager (browser, offline)
 *   js/ts      → jsRunner Worker via WorkerPool (browser sandbox)
 *   others     → Judge0 CE (free public instance, no key)
 *
 * Falls back to Judge0 if workers fail.
 *
 * S137 — pyPool rimpiazzato con workerManager.ensureSpawned("py")
 *   così RuntimeDiagnosticsPanel legge lo stato reale via getStatus("py").
 *
 * S246-Fix: WorkerPool NON usa più URL stringa runtime.
 *   Vite richiede che new URL("...", import.meta.url) sia STATICO —
 *   il path deve essere un literal string nel sorgente, non una variabile.
 *   URL runtime → Vite non bundla il worker → 404 in produzione → HTML
 *   → TypeError: 'text/html' is not a valid JavaScript MIME type.
 *
 *   Fix: WorkerPool crea il Worker con URL statico direttamente in ensureWorker().
 *
 * P6-1: JsWorkerPool rimpiazzato con workerManager.ensureSpawned("js").
 *   Su iOS, WorkerManager termina il Worker opposto prima di spawnare (js↔py swap)
 *   → max 2 Worker (1 streamWorker + 1 code runner) → no crash iOS.
 */

import { executionQueue } from "./ExecutionQueue";
import { workerManager }  from "./WorkerManager";
import { ff }             from "@/lib/featureFlags";
import { makeTimedSignal } from "@/lib/agentLoop/networkConstants"; // Loop-16: iOS-safe

export type RuntimeTarget = "browser-js" | "browser-py" | "judge0";

export interface RunOptions {
  language: string;
  code:     string;
  stdin?:   string;
  packages?: string[];
  timeout?:  number;
}

export interface RunResult {
  stdout:   string;
  stderr:   string;
  exitCode: number;
  time:     number;
  runtime:  RuntimeTarget;
}

type WorkerMsg =
  | { type: "stdout";  id: string; text: string }
  | { type: "stderr";  id: string; text: string }
  | { type: "done";    id: string; exitCode: number; time: number }
  | { type: "error";   id: string; message: string }
  | { type: "loading"; progress: number }
  | { type: "ready" };

const JUDGE0_CE = "https://ce.judge0.com";

const JUDGE0_LANG_IDS: Record<string, number> = {
  python: 71, py: 71,
  javascript: 63, js: 63,
  typescript: 74, ts: 74,
  go: 60,
  rust: 73,
  java: 62,
  cpp: 54, "c++": 54,
  c: 50,
  bash: 46, sh: 46,
  ruby: 72,
  php: 68,
  kotlin: 78,
  swift: 83,
  r: 80,
};

function routeRuntime(lang: string): RuntimeTarget {
  const l = lang.toLowerCase();
  if (l === "python" || l === "py") return "browser-py";
  if (l === "javascript" || l === "js") return "browser-js";
  return "judge0";
}

// ─── JS worker helper via WorkerManager (P6-1) ───────────────────────────────
// JsWorkerPool rimossa: JS ora usa workerManager.ensureSpawned("js") come Python.
// Su iOS, WorkerManager.spawn() termina automaticamente il Worker opposto prima
// di spawnare → garantisce max 2 Worker totali (1 stream + 1 code runner).
// L'URL jsRunner.worker.ts rimane statico nel _defaultFactory di WorkerManager.ts.
async function runInJsWorker(id: string, msgPayload: object, timeout: number): Promise<RunResult> {
  const workerLike = workerManager.ensureSpawned("js");
  const worker     = workerLike as unknown as Worker;

  let stdout   = "";
  let stderr   = "";
  let exitCode = 0;
  let time     = 0;

  return new Promise<RunResult>((resolve, reject) => {
    const timer = setTimeout(() => {
      worker.removeEventListener("message", handler);
      reject(new Error(`jsRunner timeout dopo ${timeout}ms`));
    }, timeout + 5_000);

    function handler(e: MessageEvent<WorkerMsg>): void {
      const data = e.data;
      if (!("id" in data) || data.id !== id) return;
      if (data.type === "stdout") stdout += data.text;
      if (data.type === "stderr") stderr += data.text;
      if (data.type === "done")  { exitCode = data.exitCode; time = data.time; }
      if (data.type === "done" || data.type === "error") {
        clearTimeout(timer);
        worker.removeEventListener("message", handler);
        if (data.type === "error") reject(new Error(data.message));
        else resolve({ stdout, stderr, exitCode, time, runtime: "browser-js" });
      }
    }

    worker.addEventListener("message", handler);
    worker.postMessage(msgPayload);
  });
}

// ─── Py worker helper via WorkerManager ──────────────────────────────────────
async function runInPyWorker(id: string, msgPayload: object, timeout: number): Promise<RunResult> {
  const workerLike = workerManager.ensureSpawned("py");
  const worker     = workerLike as unknown as Worker;

  let stdout   = "";
  let stderr   = "";
  let exitCode = 0;
  let time     = 0;

  return new Promise<RunResult>((resolve, reject) => {
    const timer = setTimeout(() => {
      worker.removeEventListener("message", handler);
      reject(new Error(`Pyodide timeout dopo ${timeout}ms`));
    }, timeout + 5_000);

    function handler(e: MessageEvent<WorkerMsg>): void {
      const data = e.data;
      if (!("id" in data) || data.id !== id) return;
      if (data.type === "stdout") stdout += data.text;
      if (data.type === "stderr") stderr += data.text;
      if (data.type === "done")  { exitCode = data.exitCode; time = data.time; }
      if (data.type === "done" || data.type === "error") {
        clearTimeout(timer);
        worker.removeEventListener("message", handler);
        if (data.type === "error") reject(new Error(data.message));
        else resolve({ stdout, stderr, exitCode, time, runtime: "browser-py" });
      }
    }

    worker.addEventListener("message", handler);
    worker.postMessage(msgPayload);
  });
}

async function runJudge0(code: string, lang: string, stdin = "", timeout = 30_000): Promise<RunResult> {
  const langId = JUDGE0_LANG_IDS[lang.toLowerCase()];
  if (!langId) throw new Error(`Linguaggio non supportato da Judge0: ${lang}`);

  const start = Date.now();

  const submitRes = await fetch(`${JUDGE0_CE}/submissions?base64_encoded=true&wait=true`, {
    method: "POST",
    headers: { "Content-Type": "application/json" },
    signal: makeTimedSignal(timeout),
    body: JSON.stringify({
      source_code: btoa(unescape(encodeURIComponent(code))),
      language_id: langId,
      stdin: btoa(unescape(encodeURIComponent(stdin))),
      base64_encoded: true,
    }),
  });

  if (!submitRes.ok) {
    throw new Error(`Judge0 HTTP ${submitRes.status}`);
  }

  const result = await submitRes.json() as {
    stdout?:          string;
    stderr?:          string;
    compile_output?:  string;
    status?:         { description?: string };
    time?:            string;
    memory?:          number;
    exit_code?:       number;
  };

  const decode = (s?: string): string => {
    if (!s) return "";
    try { return decodeURIComponent(escape(atob(s))); } catch { return s; }
  };

  const stderr = [decode(result.stderr), decode(result.compile_output)].filter(Boolean).join("\n");

  return {
    stdout:   decode(result.stdout),
    stderr,
    exitCode: result.exit_code ?? 0,
    time:     Date.now() - start,
    runtime:  "judge0",
  };
}

export class RuntimeManager {
  private static idCounter = 0;
  private static nextId() { return `run-${Date.now()}-${++RuntimeManager.idCounter}`; }

  async execute(opts: RunOptions): Promise<RunResult> {
    const id      = RuntimeManager.nextId();
    const lang    = opts.language.toLowerCase();
    const target  = routeRuntime(lang);
    const timeout = opts.timeout ?? 30_000;

    return executionQueue.enqueue<RunResult>(id, async () => {
      if (target === "browser-js") {
        try {
          const result = await runInJsWorker(id, {
            type: "run", id,
            code: opts.code,
            timeout,
          }, timeout);
          result.runtime = "browser-js";
          return result;
        } catch {
          return runJudge0(opts.code, lang, opts.stdin, timeout);
        }
      }

      if (target === "browser-py") {
        if (ff("PYODIDE_WORKER")) {
          try {
            const result = await runInPyWorker(id, {
              type:     "run",
              id,
              code:     opts.code,
              packages: opts.packages ?? [],
              timeout,
            }, timeout);
            return result;
          } catch {
            // Worker crash → Judge0 fallback silenzioso
          }
        }
        return runJudge0(opts.code, "python", opts.stdin, timeout);
      }

      return runJudge0(opts.code, lang, opts.stdin, timeout);
    }, { timeout: timeout + 10_000 });
  }

  cancel(id: string) {
    // P6-1: JS usa workerManager (rimossa JsWorkerPool)
    const jsStatus = workerManager.getStatus("js");
    if (jsStatus.spawned) {
      try {
        const wjs = workerManager.ensureSpawned("js") as unknown as Worker;
        wjs.postMessage({ type: "cancel", id });
      } catch { /* ignora */ }
    }
    const pyStatus = workerManager.getStatus("py");
    if (pyStatus.spawned) {
      try {
        const w = workerManager.ensureSpawned("py") as unknown as Worker;
        w.postMessage({ type: "cancel", id });
      } catch { /* ignora */ }
    }
    executionQueue.cancel(id);
  }
}

export const runtimeManager = new RuntimeManager();