import { Worker } from "node:worker_threads";

const KEY_PATTERN = /^[A-Za-z0-9][A-Za-z0-9._-]{0,127}$/;

const WORKER_SOURCE = String.raw`
const { parentPort } = require("node:worker_threads");
const vm = require("node:vm");
const { inspect } = require("node:util");

let nextCallId = 0;
const pending = new Map();
const runKeyPattern = /^[A-Za-z0-9][A-Za-z0-9._-]{0,127}$/;

function stableRunJson(value) {
  if (Array.isArray(value)) return "[" + value.map(stableRunJson).join(",") + "]";
  if (value && typeof value === "object") return "{" + Object.keys(value).sort().map((key) => JSON.stringify(key) + ":" + stableRunJson(value[key])).join(",") + "}";
  return JSON.stringify(value) ?? "undefined";
}

function hostCall(method, args) {
  return new Promise((resolve, reject) => {
    const callId = ++nextCallId;
    pending.set(callId, { resolve, reject });
    parentPort.postMessage({ type: "call", callId, method, args });
  });
}

function formatRef(result) {
  if (!result || typeof result !== "object") throw new Error("runs.ref(result) requires a run result object.");
  const parts = ["run " + (result.key || "unknown")];
  if (result.runId) parts.push("id=" + String(result.runId).slice(0, 8));
  return "[" + parts.join("; ") + "]";
}

const runFingerprints = new Map();

function validateRunCall(key, params, label, fingerprints) {
  if (typeof key !== "string" || !runKeyPattern.test(key)) throw new Error(label + " has an invalid key.");
  if (!params || typeof params !== "object" || Array.isArray(params)) throw new Error(label + " requires a params object.");
  if (Object.prototype.hasOwnProperty.call(params, "action") || Object.prototype.hasOwnProperty.call(params, "workflowScript") || Object.prototype.hasOwnProperty.call(params, "tasks") || Object.prototype.hasOwnProperty.call(params, "chain") || Object.prototype.hasOwnProperty.call(params, "concurrency") || Object.prototype.hasOwnProperty.call(params, "chainDir")) {
    const hint = label === "runs.run" ? "; use runs.all(...) and JavaScript control flow for orchestration." : ".";
    throw new Error(label + " accepts one child via { agent, task } and execution controls only" + hint);
  }
  if (params.worktree !== undefined && typeof params.worktree !== "boolean") throw new Error(label + " worktree must be true or false.");
  assertJsonValue(params, label + " params");
  const fingerprint = stableRunJson(params);
  const existing = fingerprints.get(key);
  if (existing !== undefined && existing !== fingerprint) throw new Error("Duplicate workflow key '" + key + "' used with incompatible launch params.");
  fingerprints.set(key, fingerprint);
}

const runs = Object.freeze({
  run(key, params) {
    validateRunCall(key, params, "runs.run", runFingerprints);
    return hostCall("run", { key, params });
  },
  all(items) {
    if (!Array.isArray(items)) throw new Error("runs.all(items) requires an array.");
    const fingerprints = new Map(runFingerprints);
    const calls = [];
    for (let index = 0; index < items.length; index++) {
      if (!Object.prototype.hasOwnProperty.call(items, index)) throw new Error("runs.all items must not contain sparse entries.");
      const item = items[index];
      if (!item || typeof item !== "object" || Array.isArray(item)) throw new Error("runs.all item " + index + " must be an object.");
      const { key, ...params } = item;
      validateRunCall(key, params, "runs.all item " + index, fingerprints);
      calls.push({ key, params });
    }
    for (const { key, params } of calls) runFingerprints.set(key, stableRunJson(params));
    return Promise.all(calls.map(({ key, params }) => hostCall("run", { key, params, collectFailure: true })));
  },
  status(keyOrRunId) { return hostCall("status", { keyOrRunId }); },
  ref: formatRef,
  refs(results) {
    if (!Array.isArray(results)) throw new Error("runs.refs(results) requires an array.");
    return results.map(formatRef).join("\n");
  },
});

let contextObjectPrototype;

const capturedConsole = Object.freeze(Object.fromEntries(
  ["log", "info", "warn", "error"].map((level) => [level, (...args) => {
    parentPort.postMessage({ type: "console", level, text: args.map((value) => typeof value === "string" ? value : inspect(value, { depth: 4, breakLength: 120 })).join(" ") });
  }]),
));

function assertJsonValue(value, path = "emit", seen = new Set()) {
  if (value === null || typeof value === "string" || typeof value === "boolean") return;
  if (typeof value === "number") {
    if (!Number.isFinite(value)) throw new Error(path + " must contain only finite JSON numbers.");
    return;
  }
  if (typeof value !== "object") throw new Error(path + " must be a JSON value; received " + typeof value + ".");
  if (seen.has(value)) throw new Error(path + " must not contain cycles.");
  seen.add(value);
  if (Array.isArray(value)) {
    for (let index = 0; index < value.length; index++) {
      if (!Object.prototype.hasOwnProperty.call(value, index)) throw new Error(path + " must not contain sparse array entries.");
      assertJsonValue(value[index], path + "[" + index + "]", seen);
    }
  } else {
    const prototype = Object.getPrototypeOf(value);
    if (prototype !== null && prototype !== Object.prototype && prototype !== contextObjectPrototype) throw new Error(path + " must contain only plain JSON objects.");
    if (Object.getOwnPropertySymbols(value).length > 0) throw new Error(path + " must not contain symbol keys.");
    for (const [key, entry] of Object.entries(value)) assertJsonValue(entry, path + "." + key, seen);
  }
  seen.delete(value);
}

parentPort.on("message", async (message) => {
  if (message.type === "response") {
    const entry = pending.get(message.callId);
    if (!entry) return;
    pending.delete(message.callId);
    if (message.ok) entry.resolve(message.value);
    else entry.reject(new Error(message.error));
    return;
  }
  if (message.type !== "start") return;
  try {
    const sandbox = { runs, emit(value) { assertJsonValue(value); parentPort.postMessage({ type: "emit", value }); }, console: capturedConsole };
    const context = vm.createContext(sandbox, { codeGeneration: { strings: false, wasm: false } });
    contextObjectPrototype = vm.runInContext("Object.prototype", context);
    const compiled = new vm.Script("(async () => {\n" + message.script + "\n})()", { filename: "workflow-script.js" });
    const value = await compiled.runInContext(context);
    const persistedValue = value === undefined ? null : value;
    assertJsonValue(persistedValue, "return");
    parentPort.postMessage({ type: "complete", value: persistedValue });
  } catch (error) {
    parentPort.postMessage({ type: "error", error: error && error.stack ? error.stack : String(error) });
  }
});
`;

export interface WorkflowScriptChildResult {
	key: string;
	ok: boolean;
	runId?: string;
	output: string;
	error?: string;
	structuredOutput?: unknown;
	artifactPaths: string[];
	results?: unknown[];
}

export interface WorkflowScriptTraceEntry {
	operation: "run" | "status";
	key: string;
	state: "started" | "completed" | "failed" | "reused";
	runId?: string;
	durationMs?: number;
	phase?: string;
	label?: string;
	error?: string;
}

export interface WorkflowScriptResult {
	value: unknown;
	emits: unknown[];
	console: Array<{ level: "log" | "info" | "warn" | "error"; text: string }>;
	trace: WorkflowScriptTraceEntry[];
	children: WorkflowScriptChildResult[];
}

export class WorkflowScriptError extends Error {
	readonly partial: Omit<WorkflowScriptResult, "value">;

	constructor(message: string, partial: Omit<WorkflowScriptResult, "value">) {
		super(message);
		this.name = "WorkflowScriptError";
		this.partial = partial;
	}
}

export interface RunWorkflowScriptOptions {
	script: string;
	timeoutMs: number;
	signal?: AbortSignal;
	launch: (key: string, params: Record<string, unknown>, signal: AbortSignal) => Promise<WorkflowScriptChildResult>;
	status: (keyOrRunId: string, signal: AbortSignal) => Promise<WorkflowScriptChildResult>;
	onTrace?: (trace: WorkflowScriptTraceEntry[]) => void;
	onEmit?: (emits: unknown[]) => void;
}

function isRecord(value: unknown): value is Record<string, unknown> {
	return !!value && typeof value === "object" && !Array.isArray(value);
}

function isPlainJsonObject(value: unknown): value is Record<string, unknown> {
	if (!isRecord(value)) return false;
	const prototype = Object.getPrototypeOf(value);
	return prototype === null || prototype === Object.prototype;
}

function omitUndefinedWorkflowValues(value: unknown, seen = new Set<object>()): unknown {
	if (value === null || typeof value !== "object") return value;
	if (seen.has(value)) return value;
	seen.add(value);
	const normalized = Array.isArray(value)
		? value.map((entry) => entry === undefined ? null : omitUndefinedWorkflowValues(entry, seen))
		: isPlainJsonObject(value)
			? Object.fromEntries(Object.entries(value).flatMap(([key, entry]) => entry === undefined ? [] : [[key, omitUndefinedWorkflowValues(entry, seen)]]))
			: value;
	seen.delete(value);
	return normalized;
}

export function assertWorkflowJsonValue(value: unknown, path = "value", seen = new Set<object>()): void {
	if (value === null || typeof value === "string" || typeof value === "boolean") return;
	if (typeof value === "number") {
		if (!Number.isFinite(value)) throw new Error(`${path} must contain only finite JSON numbers.`);
		return;
	}
	if (typeof value !== "object") throw new Error(`${path} must be a JSON value; received ${typeof value}.`);
	if (seen.has(value)) throw new Error(`${path} must not contain cycles.`);
	seen.add(value);
	if (Array.isArray(value)) {
		for (let index = 0; index < value.length; index++) {
			if (!Object.hasOwn(value, index)) throw new Error(`${path} must not contain sparse array entries.`);
			assertWorkflowJsonValue(value[index], `${path}[${index}]`, seen);
		}
	} else {
		const prototype = Object.getPrototypeOf(value);
		if (prototype !== null && prototype !== Object.prototype) throw new Error(`${path} must contain only plain JSON objects.`);
		if (Object.getOwnPropertySymbols(value).length > 0) throw new Error(`${path} must not contain symbol keys.`);
		for (const [key, entry] of Object.entries(value)) assertWorkflowJsonValue(entry, `${path}.${key}`, seen);
	}
	seen.delete(value);
}

export function formatWorkflowJsonPreview(value: unknown, maxLength: number): string | undefined {
	try {
		assertWorkflowJsonValue(value);
		const serialized = JSON.stringify(value);
		return typeof serialized === "string" ? serialized.slice(0, maxLength) : undefined;
	} catch {
		return undefined;
	}
}

function stableJson(value: unknown): string {
	if (Array.isArray(value)) return `[${value.map(stableJson).join(",")}]`;
	if (isRecord(value)) return `{${Object.keys(value).sort().map((key) => `${JSON.stringify(key)}:${stableJson(value[key])}`).join(",")}}`;
	return JSON.stringify(value) ?? "undefined";
}

function validateKey(value: unknown): string {
	if (typeof value !== "string" || !KEY_PATTERN.test(value)) {
		throw new Error("runs.run key must be 1-128 characters using letters, numbers, '.', '_' or '-', and start with a letter or number.");
	}
	return value;
}

function workflowStringMetadata(params: Record<string, unknown>): Pick<WorkflowScriptTraceEntry, "phase" | "label"> {
	return {
		...(typeof params.phase === "string" && params.phase.trim() ? { phase: params.phase.trim() } : {}),
		...(typeof params.label === "string" && params.label.trim() ? { label: params.label.trim() } : {}),
	};
}

export async function runWorkflowScript(options: RunWorkflowScriptOptions): Promise<WorkflowScriptResult> {
	if (!options.script.trim()) throw new Error("workflowScript must not be empty.");
	if (!Number.isInteger(options.timeoutMs) || options.timeoutMs < 1) throw new Error("workflow script timeout must be a positive integer.");

	const worker = new Worker(WORKER_SOURCE, { eval: true });
	const emits: unknown[] = [];
	const consoleEntries: WorkflowScriptResult["console"] = [];
	const trace: WorkflowScriptTraceEntry[] = [];
	const children = new Map<string, WorkflowScriptChildResult>();
	const childOrder: string[] = [];
	const launches = new Map<string, { fingerprint: string; promise: Promise<WorkflowScriptChildResult> }>();
	const childController = new AbortController();
	let settled = false;

	const partial = (): Omit<WorkflowScriptResult, "value"> => ({ emits, console: consoleEntries, trace, children: childOrder.flatMap((key) => {
		const child = children.get(key);
		return child ? [child] : [];
	}) });
	const traceChanged = () => options.onTrace?.([...trace]);

	return await new Promise<WorkflowScriptResult>((resolve, reject) => {
		const finish = (outcome: { value: unknown } | { error: Error }) => {
			if (settled) return;
			settled = true;
			clearTimeout(timer);
			options.signal?.removeEventListener("abort", onAbort);
			void worker.terminate();
			childController.abort("error" in outcome ? outcome.error : new Error("Workflow script completed; unawaited child launches are aborted."));
			if ("error" in outcome) reject(new WorkflowScriptError(outcome.error.message, partial()));
			else resolve({ value: outcome.value, ...partial() });
		};
		const onAbort = () => finish({ error: new Error("Workflow script aborted.") });
		const timer = setTimeout(() => finish({ error: new Error(`Workflow script timed out after ${options.timeoutMs}ms.`) }), options.timeoutMs);
		options.signal?.addEventListener("abort", onAbort, { once: true });
		if (options.signal?.aborted) return onAbort();

		worker.on("error", (error) => finish({ error: new Error(`Workflow worker failed: ${error instanceof Error ? error.message : String(error)}`) }));
		worker.on("exit", (code) => {
			if (!settled && code !== 0) finish({ error: new Error(`Workflow worker exited with code ${code}.`) });
		});
		worker.on("message", (message: Record<string, unknown>) => {
			if (message.type === "emit") {
				try {
					assertWorkflowJsonValue(message.value, "emit");
				} catch (error) {
					finish({ error: new Error(`Workflow emit could not be persisted: ${error instanceof Error ? error.message : String(error)}`) });
					return;
				}
				emits.push(message.value);
				try {
					options.onEmit?.([...emits]);
				} catch (error) {
					emits.pop();
					finish({ error: new Error(`Workflow emit could not be persisted: ${error instanceof Error ? error.message : String(error)}`) });
				}
				return;
			}
			if (message.type === "console") {
				const level = message.level;
				if ((level === "log" || level === "info" || level === "warn" || level === "error") && typeof message.text === "string") consoleEntries.push({ level, text: message.text });
				return;
			}
			if (message.type === "complete") {
				try {
					assertWorkflowJsonValue(message.value, "return");
				} catch (error) {
					return finish({ error: new Error(`Workflow return could not be persisted: ${error instanceof Error ? error.message : String(error)}`) });
				}
				return finish({ value: message.value });
			}
			if (message.type === "error") return finish({ error: new Error(typeof message.error === "string" ? message.error : "Workflow script failed.") });
			if (message.type !== "call" || typeof message.callId !== "number" || typeof message.method !== "string" || !isRecord(message.args)) return;

			const respond = (promise: Promise<WorkflowScriptChildResult>) => {
				void promise.then(
					(value) => worker.postMessage({ type: "response", callId: message.callId, ok: true, value: omitUndefinedWorkflowValues(value) }),
					(error: unknown) => worker.postMessage({ type: "response", callId: message.callId, ok: false, error: error instanceof Error ? error.message : String(error) }),
				);
			};

			if (message.method === "status") {
				const keyOrRunId = message.args.keyOrRunId;
				if (typeof keyOrRunId !== "string" || !keyOrRunId.trim()) return respond(Promise.reject(new Error("runs.status(keyOrRunId) requires a non-empty string.")));
				const known = children.get(keyOrRunId);
				const target = known?.runId ?? keyOrRunId;
				trace.push({ operation: "status", key: keyOrRunId, state: "started", ...(known?.runId ? { runId: known.runId } : {}) });
				traceChanged();
				respond(options.status(target, childController.signal).then((result) => {
					trace.push({ operation: "status", key: keyOrRunId, state: result.ok ? "completed" : "failed", ...(result.runId ? { runId: result.runId } : {}), ...(!result.ok ? { error: result.output } : {}) });
					traceChanged();
					if (!result.ok) throw new Error(`Status '${keyOrRunId}' failed: ${result.output}`);
					return result;
				}));
				return;
			}
			if (message.method !== "run") return respond(Promise.reject(new Error(`Unknown runs API method '${message.method}'.`)));

			let key: string;
			try {
				key = validateKey(message.args.key);
			} catch (error) {
				return respond(Promise.reject(error));
			}
			const params = message.args.params;
			if (!isRecord(params)) return respond(Promise.reject(new Error(`runs.run('${key}', params) requires a params object.`)));
			if (params.action !== undefined) return respond(Promise.reject(new Error(`runs.run('${key}') accepts execution params only; management action is not allowed.`)));
			if (params.workflowScript !== undefined) return respond(Promise.reject(new Error(`runs.run('${key}') cannot start a nested workflow script.`)));
			if (params.tasks !== undefined || params.chain !== undefined || params.concurrency !== undefined || params.chainDir !== undefined) {
				return respond(Promise.reject(new Error(`runs.run('${key}') accepts one child via { agent, task }; use runs.all(...) and JavaScript control flow for orchestration.`)));
			}
			if (params.worktree !== undefined && typeof params.worktree !== "boolean") {
				return respond(Promise.reject(new Error(`runs.run('${key}') worktree must be true or false.`)));
			}
			const collectFailure = message.args.collectFailure === true;
			const deliver = (promise: Promise<WorkflowScriptChildResult>) => collectFailure
				? promise
				: promise.then((result) => {
					if (!result.ok) throw new Error(`Run '${key}' failed: ${result.error ?? result.output}`);
					return result;
				});
			const fingerprint = stableJson(params);
			const existing = launches.get(key);
			if (existing) {
				if (existing.fingerprint !== fingerprint) return respond(Promise.reject(new Error(`Duplicate workflow key '${key}' used with incompatible launch params.`)));
				trace.push({ operation: "run", key, state: "reused", ...workflowStringMetadata(params) });
				traceChanged();
				return respond(deliver(existing.promise));
			}

			const startedAt = Date.now();
			childOrder.push(key);
			trace.push({ operation: "run", key, state: "started", ...workflowStringMetadata(params) });
			traceChanged();
			const promise = Promise.resolve().then(() => options.launch(key, { ...params, async: params.async ?? false }, childController.signal)).then((result) => {
				const normalized = !result.ok && !result.error ? { ...result, error: result.output } : result;
				children.set(key, normalized);
				trace.push({ operation: "run", key, state: normalized.ok ? "completed" : "failed", durationMs: Date.now() - startedAt, ...workflowStringMetadata(params), ...(normalized.runId ? { runId: normalized.runId } : {}), ...(!normalized.ok ? { error: normalized.error ?? normalized.output } : {}) });
				traceChanged();
				return normalized;
			}, (error: unknown) => {
				const text = error instanceof Error ? error.message : String(error);
				const failure: WorkflowScriptChildResult = { key, ok: false, output: text, error: text, artifactPaths: [] };
				children.set(key, failure);
				trace.push({ operation: "run", key, state: "failed", durationMs: Date.now() - startedAt, ...workflowStringMetadata(params), error: text });
				traceChanged();
				return failure;
			});
			launches.set(key, { fingerprint, promise });
			respond(deliver(promise));
		});

		worker.postMessage({ type: "start", script: options.script });
	});
}