import { useEffect, useMemo, useRef, useState } from "react";
import { AnimatePresence, motion } from "framer-motion";
import { ArrowUpRight } from "lucide-react";
import MessageBubble from "./MessageBubble";
import ChatButton from "./ChatButton";
import {
  matchAnswer,
  outOfScopeAnswer,
  suggestedQuestions,
} from "./qaMap";

type Message = {
  id: string;
  role: "user" | "bot";
  text: string;
};

const welcomeMessage: Message = {
  id: "welcome",
  role: "bot",
  text: "Hi 👋 I’m QuantFortune Assistant. How can I help you today?",
};

export default function ChatWidget() {
  const [open, setOpen] = useState(false);
  const [input, setInput] = useState("");
  const [messages, setMessages] = useState<Message[]>([welcomeMessage]);
  const [typing, setTyping] = useState(false);
  const [showSuggestions, setShowSuggestions] = useState(true);
  const endRef = useRef<HTMLDivElement | null>(null);
  const debounceRef = useRef<number | null>(null);
  const suggestTimerRef = useRef<number | null>(null);

  useEffect(() => {
    endRef.current?.scrollIntoView({ behavior: "smooth" });
  }, [messages, typing, open]);

  const handleSend = (question: string) => {
    const trimmed = question.trim();
    if (!trimmed) return;
    const matched = matchAnswer(trimmed);
    if (!matched) {
      return;
    }
    if (debounceRef.current) {
      window.clearTimeout(debounceRef.current);
    }
    if (suggestTimerRef.current) {
      window.clearTimeout(suggestTimerRef.current);
    }
    debounceRef.current = window.setTimeout(() => {
      const userMessage: Message = {
        id: `u_${Date.now()}`,
        role: "user",
        text: trimmed,
      };
      setMessages((prev) => [...prev, userMessage]);
      setInput("");
      const answer = matched ?? outOfScopeAnswer;
      const delay = 500 + Math.floor(Math.random() * 300);
      setTyping(true);
      setShowSuggestions(false);
      window.setTimeout(() => {
        setTyping(false);
        const botMessage: Message = {
          id: `b_${Date.now()}`,
          role: "bot",
          text: answer,
        };
        setMessages((prev) => [...prev, botMessage]);
        suggestTimerRef.current = window.setTimeout(() => {
          if (!input.trim()) {
            setShowSuggestions(true);
          }
        }, 1400);
      }, delay);
    }, 250);
  };

  const chips = useMemo(() => suggestedQuestions.slice(0, 10), []);
  const inputAnswer = matchAnswer(input);
  const showHint = input.trim().length > 0 && !inputAnswer;

  return (
    <>
      <ChatButton open={open} onToggle={() => setOpen((prev) => !prev)} />
      <AnimatePresence>
        {open && (
          <motion.div
            initial={{ opacity: 0, y: 20, scale: 0.98 }}
            animate={{ opacity: 1, y: 0, scale: 1 }}
            exit={{ opacity: 0, y: 20, scale: 0.98 }}
            transition={{ duration: 0.25, ease: "easeOut" }}
            className="fixed bottom-20 left-3 right-3 z-[60] h-[min(68vh,32rem)] sm:bottom-6 sm:left-auto sm:right-4 sm:top-20 sm:h-auto sm:w-[372px] sm:max-w-[calc(100vw-2rem)]"
          >
            <div className="flex h-full flex-col overflow-hidden rounded-3xl border border-white/10 bg-slate-900/70 shadow-2xl backdrop-blur-xl">
              <div className="flex items-center justify-between border-b border-white/10 px-5 py-4">
                <div>
                  <h3 className="text-base font-semibold text-slate-100">
                    QuantFortune Assistant
                  </h3>
                  <p className="text-xs text-slate-400">
                    Instant answers • Always on
                  </p>
                </div>
                <button
                  onClick={() => setOpen(false)}
                  className="text-slate-400 hover:text-slate-200"
                  aria-label="Close"
                >
                  ✕
                </button>
              </div>

              <div className="flex-1 space-y-5 overflow-y-auto px-5 py-6">
                {messages.map((msg) => (
                  <MessageBubble key={msg.id} role={msg.role} text={msg.text} />
                ))}
                {typing && (
                  <motion.div
                    initial={{ opacity: 0 }}
                    animate={{ opacity: 1 }}
                    className="flex items-center gap-2 text-xs text-slate-400"
                  >
                    <span className="h-2 w-2 animate-pulse rounded-full bg-slate-400" />
                    <span className="h-2 w-2 animate-pulse rounded-full bg-slate-400 [animation-delay:160ms]" />
                    <span className="h-2 w-2 animate-pulse rounded-full bg-slate-400 [animation-delay:320ms]" />
                    <span>Typing...</span>
                  </motion.div>
                )}
                <div ref={endRef} />
              </div>

              <div className="border-t border-white/10 px-4 pb-4">
                {showSuggestions && (
                  <div className="max-h-56 space-y-2 overflow-y-auto pt-3 pr-1">
                    {chips.map((chip) => (
                      <motion.button
                        key={chip}
                        whileHover={{ y: -2 }}
                        whileTap={{ scale: 0.98 }}
                        onClick={() => handleSend(chip)}
                        className="flex w-full items-center justify-between rounded-xl border border-white/10 bg-white/5 px-3 py-2 text-left text-xs text-slate-200 transition hover:border-sky-400/40 hover:bg-sky-500/10"
                      >
                        <span className="flex items-center gap-2">
                          <span className="text-sky-300">➜</span>
                          {chip}
                        </span>
                        <span className="text-slate-500">↗</span>
                      </motion.button>
                    ))}
                  </div>
                )}
                <div className="mt-3">
                  <div className="relative">
                    <input
                      value={input}
                      onChange={(e) => setInput(e.target.value)}
                      onKeyDown={(e) => {
                        if (e.key === "Enter") {
                          e.preventDefault();
                          handleSend(input);
                        }
                      }}
                      placeholder="Ask about QuantFortune, SIPs, or broker connection…"
                      className="w-full rounded-full border border-white/10 bg-white/5 px-4 py-2 pr-10 text-sm text-slate-100 placeholder:text-slate-500 focus:border-sky-400/50 focus:outline-none"
                    />
                    <button
                      onClick={() => handleSend(input)}
                      className="absolute right-2 top-1/2 -translate-y-1/2 rounded-full bg-sky-500 p-2 text-white hover:bg-sky-400"
                      aria-label="Send"
                      disabled={!inputAnswer}
                    >
                      <ArrowUpRight className="h-4 w-4" />
                    </button>
                  </div>
                  {showHint && (
                    <p className="mt-2 text-xs text-slate-500">
                      Try a suggested question for instant answers.
                    </p>
                  )}
                </div>
              </div>
            </div>
          </motion.div>
        )}
      </AnimatePresence>
    </>
  );
}