"use client";

import {
	createContext,
	type ReactNode,
	useCallback,
	useContext,
	useEffect,
	useRef,
	useState,
} from "react";
import type { ChatBoxConfig, ChatContextValue, Message } from "./lib/types";

const ChatContext = createContext<ChatContextValue | null>(null);

export function useChatContext() {
	const context = useContext(ChatContext);
	if (!context) {
		throw new Error("useChatContext must be used within ChatProvider");
	}
	return context;
}

function generateSessionId(): string {
	return `session_${Date.now()}_${Math.random().toString(36).slice(2, 9)}`;
}

function generateId(): string {
	return `msg_${Date.now()}_${Math.random().toString(36).slice(2, 9)}`;
}

interface ChatProviderProps {
	children: ReactNode;
	config?: ChatBoxConfig;
}

export function ChatProvider({ children, config = {} }: ChatProviderProps) {
	const {
		apiEndpoint = "https://apis.do/chat",
		enableEmailCapture = true,
		emailPromptDelay = 1,
		persistSession = true,
	} = config;

	const [messages, setMessages] = useState<Message[]>([]);
	const [isTyping, setIsTyping] = useState(false);
	const [showEmailCapture, setShowEmailCapture] = useState(false);
	const [email, setEmail] = useState<string | null>(null);
	const [sessionId] = useState(() => generateSessionId());
	const [hasShownEmailCapture, setHasShownEmailCapture] = useState(false);
	const [isOpen, setIsOpen] = useState(config.showOnMount ?? false);
	const [assistantResponseCount, setAssistantResponseCount] = useState(0);
	const [unreadCount, setUnreadCount] = useState(0);
	const lastUserMessageRef = useRef<string | null>(null);

	// Load persisted state
	useEffect(() => {
		if (!persistSession) return;

		const saved = localStorage.getItem(`chatbox-${sessionId}`);
		if (saved) {
			try {
				const { messages: savedMessages, email: savedEmail } =
					JSON.parse(saved);
				setMessages(
					savedMessages.map((m: Message) => ({
						...m,
						timestamp: new Date(m.timestamp),
					})),
				);
				setEmail(savedEmail);
			} catch {
				// Ignore parse errors
			}
		}
	}, [sessionId, persistSession]);

	// Persist state
	useEffect(() => {
		if (!persistSession) return;

		if (messages.length > 0 || email) {
			localStorage.setItem(
				`chatbox-${sessionId}`,
				JSON.stringify({
					messages,
					email,
				}),
			);
		}
	}, [messages, email, sessionId, persistSession]);

	// Reset unread count when chat is opened
	useEffect(() => {
		if (isOpen) {
			setUnreadCount(0);
		}
	}, [isOpen]);

	const sendMessage = useCallback(
		async (content: string) => {
			lastUserMessageRef.current = content;

			const userMessage: Message = {
				id: generateId(),
				role: "user",
				content,
				timestamp: new Date(),
			};

			setMessages((prev) => [...prev, userMessage]);
			setIsTyping(true);

			try {
				const response = await fetch(apiEndpoint, {
					method: "POST",
					headers: { "Content-Type": "application/json" },
					body: JSON.stringify({
						sessionId,
						message: content,
						email,
					}),
				});

				const data = await response.json();

				const assistantMessage: Message = {
					id: generateId(),
					role: "assistant",
					content: data.response,
					timestamp: new Date(),
				};

				setMessages((prev) => [...prev, assistantMessage]);

				// Increment unread if chat is closed
				if (!isOpen) {
					setUnreadCount((prev) => prev + 1);
				}

				const newCount = assistantResponseCount + 1;
				setAssistantResponseCount(newCount);

				// Show email capture after configured number of AI responses
				if (
					enableEmailCapture &&
					!hasShownEmailCapture &&
					!email &&
					newCount >= emailPromptDelay
				) {
					setShowEmailCapture(true);
					setHasShownEmailCapture(true);
				}
			} catch {
				const errorMessage: Message = {
					id: generateId(),
					role: "assistant",
					content: "Sorry, I'm having trouble connecting. Please try again.",
					timestamp: new Date(),
					isError: true,
				};
				setMessages((prev) => [...prev, errorMessage]);
			} finally {
				setIsTyping(false);
			}
		},
		[
			apiEndpoint,
			sessionId,
			email,
			hasShownEmailCapture,
			enableEmailCapture,
			emailPromptDelay,
			assistantResponseCount,
			isOpen,
		],
	);

	const retryLastMessage = useCallback(async () => {
		if (!lastUserMessageRef.current) return;

		// Remove the last error message
		setMessages((prev) => {
			const lastMessage = prev[prev.length - 1];
			if (lastMessage?.isError) {
				return prev.slice(0, -1);
			}
			return prev;
		});

		// Also remove the last user message since sendMessage will add it again
		setMessages((prev) => {
			const lastMessage = prev[prev.length - 1];
			if (lastMessage?.role === "user") {
				return prev.slice(0, -1);
			}
			return prev;
		});

		// Retry sending
		await sendMessage(lastUserMessageRef.current);
	}, [sendMessage]);

	const captureEmail = useCallback(
		async (newEmail: string) => {
			await fetch(`${apiEndpoint}/email`, {
				method: "POST",
				headers: { "Content-Type": "application/json" },
				body: JSON.stringify({ sessionId, email: newEmail }),
			});
			setEmail(newEmail);
			setShowEmailCapture(false);
		},
		[apiEndpoint, sessionId],
	);

	const dismissEmailCapture = useCallback(() => {
		setShowEmailCapture(false);
	}, []);

	const markAsRead = useCallback(() => {
		setUnreadCount(0);
	}, []);

	return (
		<ChatContext.Provider
			value={{
				messages,
				isTyping,
				showEmailCapture,
				email,
				sessionId,
				isOpen,
				unreadCount,
				config,
				sendMessage,
				retryLastMessage,
				captureEmail,
				dismissEmailCapture,
				setIsOpen,
				markAsRead,
			}}
		>
			{children}
		</ChatContext.Provider>
	);
}