// NEVER convert to top-level import - breaks browser/Vite builds (web-ui)
let _os: typeof import("node:os") | null = null;
if (typeof process !== "undefined" && (process.versions?.node || process.versions?.bun)) {
	import("node:os").then((m) => {
		_os = m;
	});
}

import type { Tool as OpenAITool, ResponseInput, ResponseStreamEvent } from "openai/resources/responses/responses.js";
import { getEnvApiKey } from "../env-api-keys.js";
import { supportsXhigh } from "../models.js";
import type {
	Api,
	AssistantMessage,
	Context,
	Model,
	SimpleStreamOptions,
	StreamFunction,
	StreamOptions,
} from "../types.js";
import { AssistantMessageEventStream } from "../utils/event-stream.js";
import { convertResponsesMessages, convertResponsesTools, processResponsesStream } from "./openai-responses-shared.js";
import { buildBaseOptions, clampReasoning } from "./simple-options.js";

// ============================================================================
// Configuration
// ============================================================================

const CODEX_URL = "https://chatgpt.com/backend-api/codex/responses";
const JWT_CLAIM_PATH = "https://api.openai.com/auth" as const;
const MAX_RETRIES = 3;
const BASE_DELAY_MS = 1000;
const CODEX_TOOL_CALL_PROVIDERS = new Set(["openai", "openai-codex", "opencode"]);

const CODEX_RESPONSE_STATUSES = new Set<CodexResponseStatus>([
	"completed",
	"incomplete",
	"failed",
	"cancelled",
	"queued",
	"in_progress",
]);

// ============================================================================
// Types
// ============================================================================

export interface OpenAICodexResponsesOptions extends StreamOptions {
	reasoningEffort?: "none" | "minimal" | "low" | "medium" | "high" | "xhigh";
	reasoningSummary?: "auto" | "concise" | "detailed" | "off" | "on" | null;
	textVerbosity?: "low" | "medium" | "high";
}

type CodexResponseStatus = "completed" | "incomplete" | "failed" | "cancelled" | "queued" | "in_progress";

interface RequestBody {
	model: string;
	store?: boolean;
	stream?: boolean;
	instructions?: string;
	input?: ResponseInput;
	tools?: OpenAITool[];
	tool_choice?: "auto";
	parallel_tool_calls?: boolean;
	temperature?: number;
	reasoning?: { effort?: string; summary?: string };
	text?: { verbosity?: string };
	include?: string[];
	prompt_cache_key?: string;
	[key: string]: unknown;
}

// ============================================================================
// Retry Helpers
// ============================================================================

function isRetryableError(status: number, errorText: string): boolean {
	if (status === 429 || status === 500 || status === 502 || status === 503 || status === 504) {
		return true;
	}
	return /rate.?limit|overloaded|service.?unavailable|upstream.?connect|connection.?refused/i.test(errorText);
}

function sleep(ms: number, signal?: AbortSignal): Promise<void> {
	return new Promise((resolve, reject) => {
		if (signal?.aborted) {
			reject(new Error("Request was aborted"));
			return;
		}
		const timeout = setTimeout(resolve, ms);
		signal?.addEventListener("abort", () => {
			clearTimeout(timeout);
			reject(new Error("Request was aborted"));
		});
	});
}

// ============================================================================
// Main Stream Function
// ============================================================================

export const streamOpenAICodexResponses: StreamFunction<"openai-codex-responses", OpenAICodexResponsesOptions> = (
	model: Model<"openai-codex-responses">,
	context: Context,
	options?: OpenAICodexResponsesOptions,
): AssistantMessageEventStream => {
	const stream = new AssistantMessageEventStream();

	(async () => {
		const output: AssistantMessage = {
			role: "assistant",
			content: [],
			api: "openai-codex-responses" as Api,
			provider: model.provider,
			model: model.id,
			usage: {
				input: 0,
				output: 0,
				cacheRead: 0,
				cacheWrite: 0,
				totalTokens: 0,
				cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
			},
			stopReason: "stop",
			timestamp: Date.now(),
		};

		try {
			const apiKey = options?.apiKey || getEnvApiKey(model.provider) || "";
			if (!apiKey) {
				throw new Error(`No API key for provider: ${model.provider}`);
			}

			const accountId = extractAccountId(apiKey);
			const body = buildRequestBody(model, context, options);
			options?.onPayload?.(body);
			const headers = buildHeaders(model.headers, options?.headers, accountId, apiKey, options?.sessionId);
			const bodyJson = JSON.stringify(body);

			// Fetch with retry logic for rate limits and transient errors
			let response: Response | undefined;
			let lastError: Error | undefined;

			for (let attempt = 0; attempt <= MAX_RETRIES; attempt++) {
				if (options?.signal?.aborted) {
					throw new Error("Request was aborted");
				}

				try {
					response = await fetch(CODEX_URL, {
						method: "POST",
						headers,
						body: bodyJson,
						signal: options?.signal,
					});

					if (response.ok) {
						break;
					}

					const errorText = await response.text();
					if (attempt < MAX_RETRIES && isRetryableError(response.status, errorText)) {
						const delayMs = BASE_DELAY_MS * 2 ** attempt;
						await sleep(delayMs, options?.signal);
						continue;
					}

					// Parse error for friendly message on final attempt or non-retryable error
					const fakeResponse = new Response(errorText, {
						status: response.status,
						statusText: response.statusText,
					});
					const info = await parseErrorResponse(fakeResponse);
					throw new Error(info.friendlyMessage || info.message);
				} catch (error) {
					if (error instanceof Error) {
						if (error.name === "AbortError" || error.message === "Request was aborted") {
							throw new Error("Request was aborted");
						}
					}
					lastError = error instanceof Error ? error : new Error(String(error));
					// Network errors are retryable
					if (attempt < MAX_RETRIES && !lastError.message.includes("usage limit")) {
						const delayMs = BASE_DELAY_MS * 2 ** attempt;
						await sleep(delayMs, options?.signal);
						continue;
					}
					throw lastError;
				}
			}

			if (!response?.ok) {
				throw lastError ?? new Error("Failed after retries");
			}

			if (!response.body) {
				throw new Error("No response body");
			}

			stream.push({ type: "start", partial: output });
			await processStream(response, output, stream, model);

			if (options?.signal?.aborted) {
				throw new Error("Request was aborted");
			}

			stream.push({ type: "done", reason: output.stopReason as "stop" | "length" | "toolUse", message: output });
			stream.end();
		} catch (error) {
			output.stopReason = options?.signal?.aborted ? "aborted" : "error";
			output.errorMessage = error instanceof Error ? error.message : String(error);
			stream.push({ type: "error", reason: output.stopReason, error: output });
			stream.end();
		}
	})();

	return stream;
};

export const streamSimpleOpenAICodexResponses: StreamFunction<"openai-codex-responses", SimpleStreamOptions> = (
	model: Model<"openai-codex-responses">,
	context: Context,
	options?: SimpleStreamOptions,
): AssistantMessageEventStream => {
	const apiKey = options?.apiKey || getEnvApiKey(model.provider);
	if (!apiKey) {
		throw new Error(`No API key for provider: ${model.provider}`);
	}

	const base = buildBaseOptions(model, options, apiKey);
	const reasoningEffort = supportsXhigh(model) ? options?.reasoning : clampReasoning(options?.reasoning);

	return streamOpenAICodexResponses(model, context, {
		...base,
		reasoningEffort,
	} satisfies OpenAICodexResponsesOptions);
};

// ============================================================================
// Request Building
// ============================================================================

function buildRequestBody(
	model: Model<"openai-codex-responses">,
	context: Context,
	options?: OpenAICodexResponsesOptions,
): RequestBody {
	const messages = convertResponsesMessages(model, context, CODEX_TOOL_CALL_PROVIDERS, {
		includeSystemPrompt: false,
	});

	const body: RequestBody = {
		model: model.id,
		store: false,
		stream: true,
		instructions: context.systemPrompt,
		input: messages,
		text: { verbosity: options?.textVerbosity || "medium" },
		include: ["reasoning.encrypted_content"],
		prompt_cache_key: options?.sessionId,
		tool_choice: "auto",
		parallel_tool_calls: true,
	};

	if (options?.temperature !== undefined) {
		body.temperature = options.temperature;
	}

	if (context.tools) {
		body.tools = convertResponsesTools(context.tools, { strict: null });
	}

	if (options?.reasoningEffort !== undefined) {
		body.reasoning = {
			effort: clampReasoningEffort(model.id, options.reasoningEffort),
			summary: options.reasoningSummary ?? "auto",
		};
	}

	return body;
}

function clampReasoningEffort(modelId: string, effort: string): string {
	const id = modelId.includes("/") ? modelId.split("/").pop()! : modelId;
	if (id.startsWith("gpt-5.2") && effort === "minimal") return "low";
	if (id === "gpt-5.1" && effort === "xhigh") return "high";
	if (id === "gpt-5.1-codex-mini") return effort === "high" || effort === "xhigh" ? "high" : "medium";
	return effort;
}

// ============================================================================
// Response Processing
// ============================================================================

async function processStream(
	response: Response,
	output: AssistantMessage,
	stream: AssistantMessageEventStream,
	model: Model<"openai-codex-responses">,
): Promise<void> {
	await processResponsesStream(mapCodexEvents(parseSSE(response)), output, stream, model);
}

async function* mapCodexEvents(events: AsyncIterable<Record<string, unknown>>): AsyncGenerator<ResponseStreamEvent> {
	for await (const event of events) {
		const type = typeof event.type === "string" ? event.type : undefined;
		if (!type) continue;

		if (type === "error") {
			const code = (event as { code?: string }).code || "";
			const message = (event as { message?: string }).message || "";
			throw new Error(`Codex error: ${message || code || JSON.stringify(event)}`);
		}

		if (type === "response.failed") {
			const msg = (event as { response?: { error?: { message?: string } } }).response?.error?.message;
			throw new Error(msg || "Codex response failed");
		}

		if (type === "response.done" || type === "response.completed") {
			const response = (event as { response?: { status?: unknown } }).response;
			const normalizedResponse = response
				? { ...response, status: normalizeCodexStatus(response.status) }
				: response;
			yield { ...event, type: "response.completed", response: normalizedResponse } as ResponseStreamEvent;
			continue;
		}

		yield event as unknown as ResponseStreamEvent;
	}
}

function normalizeCodexStatus(status: unknown): CodexResponseStatus | undefined {
	if (typeof status !== "string") return undefined;
	return CODEX_RESPONSE_STATUSES.has(status as CodexResponseStatus) ? (status as CodexResponseStatus) : undefined;
}

// ============================================================================
// SSE Parsing
// ============================================================================

async function* parseSSE(response: Response): AsyncGenerator<Record<string, unknown>> {
	if (!response.body) return;

	const reader = response.body.getReader();
	const decoder = new TextDecoder();
	let buffer = "";

	while (true) {
		const { done, value } = await reader.read();
		if (done) break;
		buffer += decoder.decode(value, { stream: true });

		let idx = buffer.indexOf("\n\n");
		while (idx !== -1) {
			const chunk = buffer.slice(0, idx);
			buffer = buffer.slice(idx + 2);

			const dataLines = chunk
				.split("\n")
				.filter((l) => l.startsWith("data:"))
				.map((l) => l.slice(5).trim());
			if (dataLines.length > 0) {
				const data = dataLines.join("\n").trim();
				if (data && data !== "[DONE]") {
					try {
						yield JSON.parse(data);
					} catch {}
				}
			}
			idx = buffer.indexOf("\n\n");
		}
	}
}

// ============================================================================
// Error Handling
// ============================================================================

async function parseErrorResponse(response: Response): Promise<{ message: string; friendlyMessage?: string }> {
	const raw = await response.text();
	let message = raw || response.statusText || "Request failed";
	let friendlyMessage: string | undefined;

	try {
		const parsed = JSON.parse(raw) as {
			error?: { code?: string; type?: string; message?: string; plan_type?: string; resets_at?: number };
		};
		const err = parsed?.error;
		if (err) {
			const code = err.code || err.type || "";
			if (/usage_limit_reached|usage_not_included|rate_limit_exceeded/i.test(code) || response.status === 429) {
				const plan = err.plan_type ? ` (${err.plan_type.toLowerCase()} plan)` : "";
				const mins = err.resets_at
					? Math.max(0, Math.round((err.resets_at * 1000 - Date.now()) / 60000))
					: undefined;
				const when = mins !== undefined ? ` Try again in ~${mins} min.` : "";
				friendlyMessage = `You have hit your ChatGPT usage limit${plan}.${when}`.trim();
			}
			message = err.message || friendlyMessage || message;
		}
	} catch {}

	return { message, friendlyMessage };
}

// ============================================================================
// Auth & Headers
// ============================================================================

function extractAccountId(token: string): string {
	try {
		const parts = token.split(".");
		if (parts.length !== 3) throw new Error("Invalid token");
		const payload = JSON.parse(atob(parts[1]));
		const accountId = payload?.[JWT_CLAIM_PATH]?.chatgpt_account_id;
		if (!accountId) throw new Error("No account ID in token");
		return accountId;
	} catch {
		throw new Error("Failed to extract accountId from token");
	}
}

function buildHeaders(
	initHeaders: Record<string, string> | undefined,
	additionalHeaders: Record<string, string> | undefined,
	accountId: string,
	token: string,
	sessionId?: string,
): Headers {
	const headers = new Headers(initHeaders);
	headers.set("Authorization", `Bearer ${token}`);
	headers.set("chatgpt-account-id", accountId);
	headers.set("OpenAI-Beta", "responses=experimental");
	headers.set("originator", "pi");
	const userAgent = _os ? `pi (${_os.platform()} ${_os.release()}; ${_os.arch()})` : "pi (browser)";
	headers.set("User-Agent", userAgent);
	headers.set("accept", "text/event-stream");
	headers.set("content-type", "application/json");
	for (const [key, value] of Object.entries(additionalHeaders || {})) {
		headers.set(key, value);
	}

	if (sessionId) {
		headers.set("session_id", sessionId);
	}

	return headers;
}