import { AnimatePresence, motion } from "framer-motion";
import { History, Mic, Send, Sparkles, Trash2, X } from "lucide-react";
import { useCallback, useEffect, useRef, useState } from "react";
import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

export interface ChatMessage {
  id: string;
  role: "user" | "assistant";
  content: string;
  ts: number;
}

export interface ChatSession {
  id: string;
  title: string;
  messages: ChatMessage[];
  createdAt: number;
  updatedAt: number;
}

const STORAGE_KEY = "qhub_chat_sessions";
const ACTIVE_KEY = "qhub_active_session";
const WELCOME_MSG: ChatMessage = {
  id: "w",
  role: "assistant",
  content: "Welcome to QHub. The sky listens.",
  ts: Date.now(),
};

function loadSessions(): ChatSession[] {
  try {
    const raw = localStorage.getItem(STORAGE_KEY);
    return raw ? (JSON.parse(raw) as ChatSession[]) : [];
  } catch {
    return [];
  }
}

function saveSessions(sessions: ChatSession[]) {
  try {
    localStorage.setItem(STORAGE_KEY, JSON.stringify(sessions));
  } catch { /* quota guard */ }
}

function newSession(): ChatSession {
  return {
    id: crypto.randomUUID(),
    title: `Chat ${new Date().toLocaleString("fa-IR", { month: "short", day: "numeric", hour: "2-digit", minute: "2-digit" })}`,
    messages: [{ ...WELCOME_MSG, id: crypto.randomUUID(), ts: Date.now() }],
    createdAt: Date.now(),
    updatedAt: Date.now(),
  };
}

interface ChatPanelProps {
  onSpeakingChange?: (speaking: boolean) => void;
}

export function ChatPanel({ onSpeakingChange }: ChatPanelProps) {
  const [expanded, setExpanded] = useState(false);
  const [historyOpen, setHistoryOpen] = useState(false);
  const [sessions, setSessions] = useState<ChatSession[]>(() => {
    const saved = loadSessions();
    if (saved.length > 0) return saved;
    const first = newSession();
    saveSessions([first]);
    return [first];
  });
  const [activeId, setActiveId] = useState<string>(() => {
    const saved = localStorage.getItem(ACTIVE_KEY);
    const all = loadSessions();
    if (saved && all.find(s => s.id === saved)) return saved;
    return all[0]?.id ?? newSession().id;
  });

  const activeSession = sessions.find(s => s.id === activeId) ?? sessions[0];
  const messages = activeSession?.messages ?? [WELCOME_MSG];

  const [draft, setDraft] = useState("");
  const [thinking, setThinking] = useState(false);
  const [listening, setListening] = useState(false);
  const scrollRef = useRef<HTMLDivElement>(null);

  // Persist whenever sessions change
  useEffect(() => {
    saveSessions(sessions);
  }, [sessions]);

  useEffect(() => {
    localStorage.setItem(ACTIVE_KEY, activeId);
  }, [activeId]);

  useEffect(() => {
    scrollRef.current?.scrollTo({ top: 1e9, behavior: "smooth" });
  }, [messages, expanded]);

  const updateActiveMessages = useCallback((updater: (prev: ChatMessage[]) => ChatMessage[]) => {
    setSessions(prev =>
      prev.map(s =>
        s.id === activeId
          ? { ...s, messages: updater(s.messages), updatedAt: Date.now() }
          : s
      )
    );
  }, [activeId]);

  const send = useCallback(() => {
    const text = draft.trim();
    if (!text) return;
    const userMsg: ChatMessage = { id: crypto.randomUUID(), role: "user", content: text, ts: Date.now() };
    updateActiveMessages(m => [...m, userMsg]);
    // Auto-title from first user message
    setSessions(prev =>
      prev.map(s => {
        if (s.id !== activeId) return s;
        const isDefault = s.title.startsWith("Chat ");
        return isDefault && s.messages.filter(x => x.role === "user").length === 0
          ? { ...s, title: text.slice(0, 40) + (text.length > 40 ? "…" : "") }
          : s;
      })
    );
    setDraft("");
    setThinking(true);
    onSpeakingChange?.(true);
    setTimeout(() => {
      const reply: ChatMessage = {
        id: crypto.randomUUID(),
        role: "assistant",
        content: synthesize(text),
        ts: Date.now(),
      };
      updateActiveMessages(m => [...m, reply]);
      setThinking(false);
      onSpeakingChange?.(false);
    }, 900 + Math.random() * 800);
  }, [draft, onSpeakingChange, updateActiveMessages, activeId]);

  const startNewSession = useCallback(() => {
    const s = newSession();
    setSessions(prev => [s, ...prev]);
    setActiveId(s.id);
    setHistoryOpen(false);
    setExpanded(true);
  }, []);

  const switchSession = useCallback((id: string) => {
    setActiveId(id);
    setHistoryOpen(false);
    setExpanded(true);
  }, []);

  const deleteSession = useCallback((id: string) => {
    setSessions(prev => {
      const next = prev.filter(s => s.id !== id);
      if (next.length === 0) {
        const fresh = newSession();
        saveSessions([fresh]);
        setActiveId(fresh.id);
        return [fresh];
      }
      if (id === activeId) setActiveId(next[0].id);
      return next;
    });
  }, [activeId]);

  return (
    <motion.div
      layout
      className={cn("fixed z-30 bottom-4 left-1/2 -translate-x-1/2 w-[min(640px,92vw)]")}
      transition={{ type: "spring", stiffness: 180, damping: 24 }}
    >
      {/* ── History side-panel ── */}
      <AnimatePresence>
        {historyOpen && (
          <motion.div
            key="history"
            initial={{ opacity: 0, x: -20 }}
            animate={{ opacity: 1, x: 0 }}
            exit={{ opacity: 0, x: -20 }}
            transition={{ duration: 0.3, ease: [0.22, 1, 0.36, 1] }}
            className="absolute bottom-full mb-2 left-0 w-64 glass-strong rounded-2xl overflow-hidden shadow-2xl"
          >
            <div className="flex items-center justify-between px-4 py-2.5 border-b border-white/5">
              <span className="text-xs font-semibold text-foreground/80">تاریخچه مکالمات</span>
              <div className="flex items-center gap-1">
                <button
                  onClick={startNewSession}
                  className="text-[10px] px-2 py-0.5 rounded-full bg-primary/20 text-primary hover:bg-primary/30 transition-colors"
                  title="مکالمه جدید"
                >
                  + جدید
                </button>
                <button onClick={() => setHistoryOpen(false)} className="text-muted-foreground hover:text-foreground transition-colors ml-1">
                  <X className="w-3.5 h-3.5" />
                </button>
              </div>
            </div>
            <div className="max-h-64 overflow-y-auto py-1">
              {sessions.length === 0 && (
                <p className="text-xs text-muted-foreground text-center py-4">هیچ مکالمه‌ای ذخیره نشده</p>
              )}
              {sessions.map(s => (
                <div
                  key={s.id}
                  className={cn(
                    "group flex items-center gap-2 px-4 py-2 cursor-pointer transition-colors hover:bg-primary/5",
                    s.id === activeId && "bg-primary/10"
                  )}
                  onClick={() => switchSession(s.id)}
                >
                  <div className="flex-1 min-w-0">
                    <div className="text-xs font-medium truncate text-foreground/90">{s.title}</div>
                    <div className="text-[10px] text-muted-foreground mt-0.5">
                      {s.messages.length} پیام · {new Date(s.updatedAt).toLocaleDateString("fa-IR")}
                    </div>
                  </div>
                  <button
                    onClick={e => { e.stopPropagation(); deleteSession(s.id); }}
                    className="opacity-0 group-hover:opacity-100 text-muted-foreground hover:text-destructive transition-all"
                    title="حذف مکالمه"
                  >
                    <Trash2 className="w-3 h-3" />
                  </button>
                </div>
              ))}
            </div>
          </motion.div>
        )}
      </AnimatePresence>

      {/* ── Messages panel ── */}
      <AnimatePresence initial={false}>
        {expanded && (
          <motion.div
            key="messages"
            initial={{ opacity: 0, y: 16, height: 0 }}
            animate={{ opacity: 1, y: 0, height: "auto" }}
            exit={{ opacity: 0, y: 16, height: 0 }}
            transition={{ duration: 0.35, ease: [0.22, 1, 0.36, 1] }}
            className="glass-strong rounded-3xl mb-2 overflow-hidden"
          >
            <div className="flex items-center justify-between px-4 py-2 border-b border-white/5">
              <div className="flex items-center gap-2 text-xs text-muted-foreground min-w-0">
                <span className="w-1.5 h-1.5 rounded-full bg-primary animate-pulse shrink-0" />
                <span className="truncate max-w-[160px]" title={activeSession?.title}>
                  {activeSession?.title ?? "Live channel"}
                </span>
              </div>
              <div className="flex items-center gap-1.5">
                <button
                  onClick={() => updateActiveMessages(() => [{ ...WELCOME_MSG, id: crypto.randomUUID(), ts: Date.now() }])}
                  className="text-muted-foreground hover:text-destructive transition-colors"
                  title="پاک کردن مکالمه"
                >
                  <Trash2 className="w-3.5 h-3.5" />
                </button>
                <button onClick={() => setExpanded(false)} className="text-muted-foreground hover:text-foreground transition-colors">
                  <X className="w-4 h-4" />
                </button>
              </div>
            </div>
            <div ref={scrollRef} className="max-h-72 overflow-y-auto px-4 py-3 space-y-3">
              {messages.map(m => (
                <motion.div
                  key={m.id}
                  initial={{ opacity: 0, y: 8 }}
                  animate={{ opacity: 1, y: 0 }}
                  className={cn("flex", m.role === "user" ? "justify-end" : "justify-start")}
                >
                  <div
                    className={cn(
                      "max-w-[80%] rounded-2xl px-3.5 py-2 text-sm leading-relaxed",
                      m.role === "user"
                        ? "bg-primary/15 text-foreground border border-primary/30"
                        : "glass text-foreground/90"
                    )}
                  >
                    {m.content}
                  </div>
                </motion.div>
              ))}
              {thinking && (
                <div className="flex items-center gap-1.5 text-xs text-muted-foreground pl-1">
                  <Sparkles className="w-3 h-3 animate-pulse" />
                  thinking
                  <span className="flex gap-0.5">
                    {[0, 1, 2].map(i => (
                      <span key={i} className="w-1 h-1 rounded-full bg-primary/70 animate-pulse" style={{ animationDelay: `${i * 0.15}s` }} />
                    ))}
                  </span>
                </div>
              )}
            </div>
          </motion.div>
        )}
      </AnimatePresence>

      {/* ── Input bar ── */}
      <div className="glass-strong rounded-full pl-2 pr-1.5 py-1.5 flex items-center gap-2">
        {/* History button */}
        <button
          onClick={() => setHistoryOpen(h => !h)}
          className={cn("rounded-full h-8 w-8 grid place-items-center transition-colors",
            historyOpen ? "bg-primary/20 text-primary" : "text-muted-foreground hover:text-primary")}
          aria-label="تاریخچه مکالمات"
          title="تاریخچه مکالمات"
        >
          <History className="w-4 h-4" />
        </button>
        {/* Toggle messages */}
        <button
          onClick={() => setExpanded(e => !e)}
          className="text-muted-foreground hover:text-primary transition-colors"
          aria-label="Toggle messages"
        >
          <Sparkles className="w-4 h-4" />
        </button>
        <input
          value={draft}
          onChange={e => setDraft(e.target.value)}
          onFocus={() => setExpanded(true)}
          onKeyDown={e => { if (e.key === "Enter") { e.preventDefault(); send(); } }}
          placeholder="Speak to the sky…"
          className="flex-1 bg-transparent outline-none text-sm placeholder:text-muted-foreground/60 py-1.5"
        />
        <Button
          variant="ghost"
          size="icon"
          onClick={() => setListening(l => !l)}
          className={cn("rounded-full h-8 w-8", listening && "bg-primary/20 text-primary")}
          title={listening ? "توقف ضبط صدا" : "شروع ضبط صدا"}
        >
          <Mic className="w-4 h-4" />
        </Button>
        <Button
          onClick={send}
          size="icon"
          className="rounded-full h-8 w-8 bg-gradient-to-br from-primary to-accent disabled:opacity-40"
          disabled={!draft.trim() || thinking}
          title="ارسال پیام"
        >
          <Send className="w-3.5 h-3.5" />
        </Button>
      </div>

      {listening && <Waveform />}
    </motion.div>
  );
}

function Waveform() {
  return (
    <div className="absolute -top-8 left-1/2 -translate-x-1/2 flex items-end gap-0.5 h-6">
      {Array.from({ length: 24 }).map((_, i) => (
        <motion.span
          key={i}
          className="w-1 rounded-full bg-gradient-to-t from-primary to-accent"
          animate={{ height: [4, 6 + Math.random() * 18, 4] }}
          transition={{ duration: 0.6 + Math.random() * 0.6, repeat: Infinity, delay: i * 0.04, ease: "easeInOut" }}
        />
      ))}
    </div>
  );
}

function synthesize(input: string) {
  const seeds = [
    "Acknowledged. Routing intent through the cognitive mesh.",
    "Signal received. Constellations realigned to your query.",
    "Processed. The orbital memory has been updated.",
    "Done. A satellite carries your request beyond the haze.",
  ];
  return `${seeds[Math.floor(Math.random() * seeds.length)]} ${input.length > 60 ? "" : "Anything else?"}`;
}