import { getPuppeteerDir, isCompiledBinary, logger, Snowflake } from "@oh-my-pi/pi-utils";
import type { Page, Target } from "puppeteer-core";
import { callSessionTool } from "../../eval/js/tool-bridge";
import type { ToolSession } from "../../sdk";
import { expandPath } from "../path-utils";
import { ToolAbortError, ToolError } from "../tool-errors";
import { pickElectronTarget } from "./attach";
import { type BrowserHandle, type BrowserKindTag, holdBrowser, releaseBrowser } from "./registry";
import type {
	ReadyInfo,
	RunErrorPayload,
	RunResultOk,
	SessionSnapshot,
	Transferable,
	Transport,
	WorkerInbound,
	WorkerInitPayload,
	WorkerOutbound,
} from "./tab-protocol";

// Worker entry. The literal string in `new Worker("./packages/coding-agent/src/tools/browser/tab-worker-entry.ts", …)`
// below is what Bun's `--compile` static analyzer needs to bundle the worker
// (registered as an additional entrypoint in `scripts/build-binary.ts`); in
// dev we resolve the same source via `import.meta.url`. Replaces the older
// `with { type: "file" }` pattern, which only copied the entry as a raw
// asset and could not resolve the worker's relative imports inside a
// compiled binary (issue #1011 was a false-positive fix — the regression
// test only checked emission, not actual worker startup).

interface WorkerHandle {
	send(msg: WorkerInbound, transferList?: Transferable[]): void;
	onMessage(handler: (msg: WorkerOutbound) => void): () => void;
	onError(handler: (error: Error) => void): () => void;
	terminate(): Promise<void>;
	readonly mode: "worker" | "inline";
}

export type DialogPolicy = "accept" | "dismiss";

export interface PendingRun {
	resolve(result: RunResultOk): void;
	reject(error: unknown): void;
	session: ToolSession;
	signal?: AbortSignal;
	toolCalls: Map<string, AbortController>;
}

export interface TabSession {
	name: string;
	browser: BrowserHandle;
	targetId: string;
	worker: WorkerHandle;
	state: "alive" | "dead";
	info: ReadyInfo;
	pending: Map<string, PendingRun>;
	dialogPolicy?: DialogPolicy;
	kindTag: BrowserKindTag;
}

export interface AcquireTabOptions {
	url?: string;
	waitUntil?: "load" | "domcontentloaded" | "networkidle0" | "networkidle2";
	viewport?: { width: number; height: number; deviceScaleFactor?: number };
	target?: string;
	signal?: AbortSignal;
	timeoutMs: number;
	dialogs?: DialogPolicy;
}

export interface AcquireTabResult {
	tab: TabSession;
	created: boolean;
}

export interface RunInTabOptions {
	code: string;
	timeoutMs: number;
	signal?: AbortSignal;
	session: ToolSession;
}

export interface ReleaseTabOptions {
	kill?: boolean;
}

const tabs = new Map<string, TabSession>();
const GRACE_MS = 750;

export function getTab(name: string): TabSession | undefined {
	return tabs.get(name);
}

export async function acquireTab(
	name: string,
	browser: BrowserHandle,
	opts: AcquireTabOptions,
): Promise<AcquireTabResult> {
	const existing = tabs.get(name);
	if (existing) {
		if (existing.browser === browser && existing.state === "alive") {
			if (opts.dialogs !== undefined && opts.dialogs !== existing.dialogPolicy) {
				await releaseTab(name, { kill: false });
			} else {
				if (opts.url) {
					await runInTabWithSnapshot(
						name,
						{
							code: `await tab.goto(${JSON.stringify(opts.url)}, { waitUntil: ${JSON.stringify(opts.waitUntil ?? "networkidle2")} });`,
							timeoutMs: opts.timeoutMs,
							signal: opts.signal,
						},
						{ cwd: process.cwd() },
					);
				}
				return { tab: tabs.get(name)!, created: false };
			}
		} else {
			await releaseTab(name, { kill: false });
		}
	}

	const initPayload = await buildInitPayload(browser, opts);
	let worker = await spawnTabWorker();
	let info: ReadyInfo;
	try {
		info = await initializeTabWorker(worker, initPayload, opts.timeoutMs + GRACE_MS);
	} catch (error) {
		// `BuildMessage`-class failures arrive asynchronously via the worker's `error` event,
		// after `spawnTabWorker`'s synchronous try/catch has already returned. Fall back to
		// the inline worker here so module-resolution failures don't poison every tab open.
		await worker.terminate().catch(() => undefined);
		if (worker.mode === "inline") {
			if (browser.refCount === 0) await releaseBrowser(browser, { kill: false });
			throw error;
		}
		logger.warn("Tab worker init failed; retrying with inline tab worker (no sync-loop guard)", {
			error: error instanceof Error ? error.message : String(error),
		});
		worker = await spawnInlineWorker();
		try {
			info = await initializeTabWorker(worker, initPayload, opts.timeoutMs + GRACE_MS);
		} catch (inlineError) {
			await worker.terminate().catch(() => undefined);
			if (browser.refCount === 0) await releaseBrowser(browser, { kill: false });
			const finalError = new ToolError(
				`Failed to start browser tab worker (inline fallback also failed): ${inlineError instanceof Error ? inlineError.message : String(inlineError)}`,
			);
			(finalError as { cause?: unknown }).cause = error;
			throw finalError;
		}
	}

	holdBrowser(browser);
	const tab: TabSession = {
		name,
		browser,
		targetId: info.targetId,
		worker,
		state: "alive",
		info,
		pending: new Map(),
		dialogPolicy: opts.dialogs,
		kindTag: browser.kind.kind,
	};
	worker.onMessage(msg => handleTabMessage(tab, msg));
	tabs.set(name, tab);
	return { tab, created: true };
}

export async function runInTab(name: string, opts: RunInTabOptions): Promise<RunResultOk> {
	return await runInTabWithSnapshot(
		name,
		{ code: opts.code, timeoutMs: opts.timeoutMs, signal: opts.signal, session: opts.session },
		{ cwd: opts.session.cwd, browserScreenshotDir: expandBrowserScreenshotDir(opts.session) },
	);
}

async function runInTabWithSnapshot(
	name: string,
	opts: { code: string; timeoutMs: number; signal?: AbortSignal; session?: ToolSession },
	snapshot: SessionSnapshot,
): Promise<RunResultOk> {
	const tab = tabs.get(name);
	if (!tab || tab.state === "dead") throw new ToolError(`Tab ${JSON.stringify(name)} is not alive. Reopen it.`);
	if (tab.pending.size > 0) throw new ToolError(`Tab ${JSON.stringify(name)} is busy`);
	const id = Snowflake.next();
	const { promise, resolve, reject } = Promise.withResolvers<RunResultOk>();
	const pending: PendingRun = {
		resolve,
		reject,
		session: opts.session ?? ({} as ToolSession),
		signal: opts.signal,
		toolCalls: new Map(),
	};
	tab.pending.set(id, pending);
	const abort = (): void => {
		tab.worker.send({ type: "abort", id });
		for (const ctrl of pending.toolCalls.values()) ctrl.abort(opts.signal?.reason);
	};
	if (opts.signal?.aborted) abort();
	else opts.signal?.addEventListener("abort", abort, { once: true });
	try {
		tab.worker.send({ type: "run", id, name, code: opts.code, timeoutMs: opts.timeoutMs, session: snapshot });
		return await raceWithTimeout(
			promise,
			opts.timeoutMs + GRACE_MS,
			"Browser code execution hung past grace; tab killed",
			async reason => await forceKillTab(name, reason),
		);
	} finally {
		opts.signal?.removeEventListener("abort", abort);
		tab.pending.delete(id);
	}
}

export async function releaseTab(name: string, opts: ReleaseTabOptions = {}): Promise<boolean> {
	const tab = tabs.get(name);
	if (!tab) {
		logger.debug("releaseTab: unknown tab", { name });
		return false;
	}
	const wasAlive = tab.state === "alive";
	tab.state = "dead";
	const closeError = new ToolError(`Tab ${JSON.stringify(name)} was closed`);
	for (const [id, pending] of tab.pending) {
		try {
			tab.worker.send({ type: "abort", id });
		} catch {}
		pending.reject(closeError);
	}
	tab.pending.clear();
	let forced = false;
	if (wasAlive) {
		try {
			tab.worker.send({ type: "close" });
			await waitForClosed(tab);
		} catch {
			forced = true;
		}
	}
	await tab.worker.terminate().catch(() => undefined);
	if (forced && tab.kindTag === "headless") await closeOrphanTarget(tab);
	await releaseBrowser(tab.browser, { kill: opts.kill ?? false });
	tabs.delete(name);
	return true;
}

export async function releaseAllTabs(opts: ReleaseTabOptions = {}): Promise<number> {
	const names = [...tabs.keys()];
	let count = 0;
	for (const name of names) {
		if (await releaseTab(name, opts)) count++;
	}
	return count;
}

export async function dropHeadlessTabs(): Promise<void> {
	const names = [...tabs.values()].filter(tab => tab.kindTag === "headless").map(tab => tab.name);
	for (const name of names) await releaseTab(name);
}

async function buildInitPayload(browser: BrowserHandle, opts: AcquireTabOptions): Promise<WorkerInitPayload> {
	const safeDir = getPuppeteerDir();
	const browserWSEndpoint = browser.browser.wsEndpoint();
	if (!browserWSEndpoint) throw new ToolError("Browser websocket endpoint is unavailable");
	if (browser.kind.kind === "headless") {
		return {
			mode: "headless",
			browserWSEndpoint,
			safeDir,
			viewport: opts.viewport,
			dialogs: opts.dialogs,
			url: opts.url,
			waitUntil: opts.waitUntil,
			timeoutMs: opts.timeoutMs,
		};
	}
	const page = await pickElectronTarget(browser.browser, opts.target);
	const targetId = await targetIdForPage(page);
	return {
		mode: "attach",
		browserWSEndpoint,
		safeDir,
		targetId,
		dialogs: opts.dialogs,
	};
}

function handleTabMessage(tab: TabSession, msg: WorkerOutbound): void {
	if (msg.type === "result") {
		const pending = tab.pending.get(msg.id);
		if (!pending) return;
		tab.pending.delete(msg.id);
		if (msg.ok) {
			pending.resolve(msg.payload);
			return;
		}
		pending.reject(errorFromPayload(msg.error));
		return;
	}
	if (msg.type === "ready") {
		tab.info = msg.info;
		return;
	}
	if (msg.type === "tool-call") {
		void dispatchToolCall(tab, msg);
		return;
	}
	if (msg.type === "log") logWorkerMessage(msg);
}

async function dispatchToolCall(tab: TabSession, msg: Extract<WorkerOutbound, { type: "tool-call" }>): Promise<void> {
	const pending = tab.pending.get(msg.runId);
	if (!pending?.session.cwd) {
		safeSend(tab, {
			type: "tool-reply",
			id: msg.id,
			reply: {
				ok: false,
				error: { name: "ToolError", message: "No active run for tool call", isToolError: true, isAbort: false },
			},
		});
		return;
	}
	const ctrl = new AbortController();
	pending.toolCalls.set(msg.id, ctrl);
	const onParentAbort = (): void => ctrl.abort(pending.signal?.reason);
	if (pending.signal?.aborted) onParentAbort();
	else pending.signal?.addEventListener("abort", onParentAbort, { once: true });
	try {
		const value = await callSessionTool(msg.name, msg.args, {
			session: pending.session,
			signal: ctrl.signal,
			emitStatus: () => {
				// Status events from tool calls aren't piped back to user code yet; the worker
				// already pushes its own helper status via the display channel.
			},
		});
		safeSend(tab, { type: "tool-reply", id: msg.id, reply: { ok: true, value } });
	} catch (error) {
		safeSend(tab, { type: "tool-reply", id: msg.id, reply: { ok: false, error: toErrorPayload(error) } });
	} finally {
		pending.toolCalls.delete(msg.id);
		pending.signal?.removeEventListener("abort", onParentAbort);
	}
}

function safeSend(tab: TabSession, msg: WorkerInbound): void {
	if (tab.state !== "alive") return;
	try {
		tab.worker.send(msg);
	} catch (err) {
		logger.debug("tab worker send failed", { error: err instanceof Error ? err.message : String(err) });
	}
}

function toErrorPayload(error: unknown): RunErrorPayload {
	if (error instanceof Error) {
		return {
			name: error.name,
			message: error.message,
			stack: error.stack,
			isAbort: error.name === "AbortError" || error.name === "ToolAbortError",
			isToolError: error instanceof ToolError || error.name === "ToolError",
		};
	}
	return { name: "Error", message: String(error), isAbort: false, isToolError: false };
}

async function forceKillTab(name: string, reason: string): Promise<void> {
	const tab = tabs.get(name);
	if (!tab) return;
	tab.state = "dead";
	const error = new ToolError(reason);
	for (const pending of tab.pending.values()) pending.reject(error);
	tab.pending.clear();
	await tab.worker.terminate().catch(() => undefined);
	if (tab.kindTag === "headless") await closeOrphanTarget(tab);
	await releaseBrowser(tab.browser, { kill: false });
	tabs.delete(name);
}

async function closeOrphanTarget(tab: TabSession): Promise<void> {
	for (const target of tab.browser.browser.targets()) {
		if ((await targetIdForTarget(target).catch(() => "")) !== tab.targetId) continue;
		const page = await target.page().catch(() => null);
		await page?.close().catch(() => undefined);
		return;
	}
}

async function waitForClosed(tab: TabSession): Promise<void> {
	const { promise, resolve } = Promise.withResolvers<void>();
	const unsubscribe = tab.worker.onMessage(msg => {
		if (msg.type === "closed") resolve();
	});
	try {
		await raceWithTimeout(promise, GRACE_MS, "Timed out closing browser tab worker");
	} finally {
		unsubscribe();
	}
}

function expandBrowserScreenshotDir(session: ToolSession): string | undefined {
	const value = session.settings.get("browser.screenshotDir") as string | undefined;
	return value ? expandPath(value) : undefined;
}

async function targetIdForPage(page: Page): Promise<string> {
	return await targetIdForTarget(page.target());
}

async function targetIdForTarget(target: Target): Promise<string> {
	const raw = target as unknown as { _targetId?: unknown };
	if (typeof raw._targetId === "string") return raw._targetId;
	const session = await target.createCDPSession();
	try {
		const info = (await session.send("Target.getTargetInfo")) as { targetInfo?: { targetId?: string } };
		if (info.targetInfo?.targetId) return info.targetInfo.targetId;
		throw new ToolError("Target id unavailable from CDP target info");
	} finally {
		await session.detach().catch(() => undefined);
	}
}

function errorFromPayload(payload: RunErrorPayload): Error {
	const error = payload.isAbort
		? new ToolAbortError()
		: payload.isToolError
			? new ToolError(payload.message)
			: new Error(payload.message);
	error.name = payload.name;
	if (payload.stack) error.stack = payload.stack;
	return error;
}

function logWorkerMessage(msg: Extract<WorkerOutbound, { type: "log" }>): void {
	if (msg.level === "debug") logger.debug(msg.msg, msg.meta);
	else if (msg.level === "warn") logger.warn(msg.msg, msg.meta);
	else logger.error(msg.msg, msg.meta);
}

async function raceWithTimeout<T>(
	promise: Promise<T>,
	timeoutMs: number,
	reason: string,
	onTimeout?: (reason: string) => Promise<void>,
): Promise<T> {
	const timeoutSignal = AbortSignal.timeout(timeoutMs);
	const { promise: timeoutPromise, reject } = Promise.withResolvers<never>();
	const onAbort = (): void => reject(new ToolError(reason));
	timeoutSignal.addEventListener("abort", onAbort, { once: true });
	try {
		return await Promise.race([promise, timeoutPromise]);
	} catch (error) {
		if (error instanceof ToolError && error.message === reason) await onTimeout?.(reason);
		throw error;
	} finally {
		timeoutSignal.removeEventListener("abort", onAbort);
	}
}

async function spawnTabWorker(): Promise<WorkerHandle> {
	try {
		const worker = isCompiledBinary()
			? new Worker("./packages/coding-agent/src/tools/browser/tab-worker-entry.ts", { type: "module" })
			: new Worker(new URL("./tab-worker-entry.ts", import.meta.url).href, { type: "module" });
		return wrapBunWorker(worker);
	} catch (err) {
		logger.warn("Bun Worker spawn failed; using inline tab worker (no sync-loop guard)", {
			error: err instanceof Error ? err.message : String(err),
		});
		return spawnInlineWorker();
	}
}

function wrapBunWorker(worker: Worker): WorkerHandle {
	return {
		mode: "worker",
		send(msg, transferList) {
			worker.postMessage(msg, { transfer: transferList ?? [] });
		},
		onMessage(handler) {
			const wrap = (event: MessageEvent): void => handler(event.data as WorkerOutbound);
			worker.addEventListener("message", wrap);
			return () => worker.removeEventListener("message", wrap);
		},
		onError(handler) {
			const onError = (event: ErrorEvent): void => handler(errorFromWorkerEvent(event));
			const onMessageError = (event: MessageEvent): void =>
				handler(new ToolError(`Tab worker message error: ${String(event.data)}`));
			worker.addEventListener("error", onError);
			worker.addEventListener("messageerror", onMessageError);
			return () => {
				worker.removeEventListener("error", onError);
				worker.removeEventListener("messageerror", onMessageError);
			};
		},
		async terminate() {
			worker.terminate();
		},
	};
}

/**
 * Inline fallback for environments where Bun cannot compile or spawn the worker
 * entry. This preserves normal browser behavior but cannot interrupt synchronous
 * infinite loops because user code runs on the main thread.
 */
async function spawnInlineWorker(): Promise<WorkerHandle> {
	const hostListeners = new Set<(message: WorkerOutbound) => void>();
	const workerListeners = new Set<(message: WorkerInbound) => void>();
	const workerTransport: Transport = {
		send: msg =>
			queueMicrotask(() => {
				for (const listener of hostListeners) listener(msg as WorkerOutbound);
			}),
		onMessage: handler => {
			const typed = handler as (message: WorkerInbound) => void;
			workerListeners.add(typed);
			return () => workerListeners.delete(typed);
		},
		close: () => {},
	};
	const { WorkerCore } = await import("./tab-worker");
	new WorkerCore(workerTransport);
	return {
		mode: "inline",
		send: msg =>
			queueMicrotask(() => {
				for (const listener of workerListeners) listener(msg);
			}),
		onMessage: handler => {
			hostListeners.add(handler);
			return () => hostListeners.delete(handler);
		},
		onError: () => () => {},
		async terminate() {},
	};
}

async function initializeTabWorker(
	worker: WorkerHandle,
	payload: WorkerInitPayload,
	timeoutMs: number,
): Promise<ReadyInfo> {
	const { promise, resolve, reject } = Promise.withResolvers<ReadyInfo>();
	const unlisten = worker.onMessage(msg => {
		if (msg.type === "ready") resolve(msg.info);
		else if (msg.type === "init-failed") reject(errorFromPayload(msg.error));
		else if (msg.type === "log") logWorkerMessage(msg);
	});
	const unlistenError = worker.onError(error => {
		reject(new ToolError(`Tab worker failed during startup: ${error.message}`));
	});
	try {
		worker.send({ type: "init", payload });
		return await raceWithTimeout(promise, timeoutMs, "Timed out initializing browser tab worker");
	} finally {
		unlisten();
		unlistenError();
	}
}

export function initializeTabWorkerForTest(
	worker: WorkerHandle,
	payload: WorkerInitPayload,
	timeoutMs: number,
): Promise<ReadyInfo> {
	return initializeTabWorker(worker, payload, timeoutMs);
}

function errorFromWorkerEvent(event: ErrorEvent): Error {
	if (event.error instanceof Error) return event.error;
	if (event.message) return new Error(event.message);
	return new Error("Unknown tab worker error");
}