"use client";

import { useState, useRef, useEffect } from "react";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Sheet, SheetContent, SheetHeader, SheetTitle } from "@/components/ui/sheet";
import { MessageCircle, Send, Bot, User } from "lucide-react";
import ReactMarkdown from "react-markdown";
import { cn } from "@/lib/utils";

type Message = {
  role: "user" | "assistant";
  content: string;
};

type Props = {
  recipeId: string;
  recipeTitle: string;
};

export function RecipeChatPanel({ recipeId, recipeTitle }: Props) {
  const [open, setOpen] = useState(false);
  const [messages, setMessages] = useState<Message[]>([]);
  const [input, setInput] = useState("");
  const [loading, setLoading] = useState(false);
  const bottomRef = useRef<HTMLDivElement>(null);

  useEffect(() => {
    if (open && bottomRef.current) {
      bottomRef.current.scrollIntoView({ behavior: "smooth" });
    }
  }, [messages, open]);

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    const question = input.trim();
    if (!question || loading) return;

    setInput("");
    setMessages((prev) => [...prev, { role: "user", content: question }]);
    setLoading(true);

    try {
      const res = await fetch("/api/v1/ai/recipe-chat", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ recipeId, question }),
      });
      const data = await res.json() as { answer?: string; error?: string };
      setMessages((prev) => [
        ...prev,
        { role: "assistant", content: data.answer ?? "Sorry, I couldn't answer that." },
      ]);
    } catch {
      setMessages((prev) => [
        ...prev,
        { role: "assistant", content: "Something went wrong. Please try again." },
      ]);
    } finally {
      setLoading(false);
    }
  };

  const suggestions = [
    "Can I substitute any ingredients?",
    "How do I know when it's done?",
    "Can I make this ahead of time?",
    "What can I serve with this?",
  ];

  return (
    <>
      <Button
        variant="default"
        size="icon"
        className="fixed bottom-6 right-6 h-12 w-12 rounded-full shadow-lg z-40"
        onClick={() => setOpen(true)}
        aria-label="Ask AI about this recipe"
      >
        <MessageCircle className="h-5 w-5" />
      </Button>

      <Sheet open={open} onOpenChange={setOpen}>
        <SheetContent side="right" className="w-full sm:w-[420px] flex flex-col p-0">
          <SheetHeader className="px-4 py-3 pr-10 border-b shrink-0">
            <SheetTitle className="text-base flex items-center gap-2">
              <Bot className="h-4 w-4 text-primary" />
              Ask about this recipe
            </SheetTitle>
            <p className="text-xs text-muted-foreground text-left">{recipeTitle}</p>
          </SheetHeader>

          <div className="flex-1 overflow-y-auto px-4 py-4 space-y-4 min-h-0">
            {messages.length === 0 && (
              <div className="space-y-3">
                <p className="text-sm text-muted-foreground text-center py-4">
                  Ask anything about this recipe — ingredients, techniques, substitutions, timing…
                </p>
                <div className="space-y-2">
                  {suggestions.map((s) => (
                    <button
                      key={s}
                      onClick={() => setInput(s)}
                      className="w-full text-left text-sm px-3 py-2 rounded-lg border bg-muted/50 hover:bg-muted transition-colors"
                    >
                      {s}
                    </button>
                  ))}
                </div>
              </div>
            )}

            {messages.map((msg, i) => (
              <div
                key={i}
                className={cn(
                  "flex gap-2 items-start",
                  msg.role === "user" && "flex-row-reverse"
                )}
              >
                <div className={cn(
                  "h-7 w-7 shrink-0 rounded-full flex items-center justify-center",
                  msg.role === "user"
                    ? "bg-primary text-primary-foreground"
                    : "bg-muted text-muted-foreground"
                )}>
                  {msg.role === "user" ? <User className="h-3.5 w-3.5" /> : <Bot className="h-3.5 w-3.5" />}
                </div>
                <div className={cn(
                  "rounded-xl px-3 py-2 text-sm max-w-[80%] leading-relaxed",
                  msg.role === "user"
                    ? "bg-primary text-primary-foreground whitespace-pre-wrap"
                    : "bg-muted space-y-2 [&_ul]:list-disc [&_ol]:list-decimal [&_ul]:pl-4 [&_ol]:pl-4 [&_strong]:font-semibold [&_li]:my-0.5"
                )}>
                  {msg.role === "assistant" ? (
                    <ReactMarkdown>{msg.content}</ReactMarkdown>
                  ) : (
                    msg.content
                  )}
                </div>
              </div>
            ))}

            {loading && (
              <div className="flex gap-2 items-start">
                <div className="h-7 w-7 shrink-0 rounded-full flex items-center justify-center bg-muted text-muted-foreground">
                  <Bot className="h-3.5 w-3.5" />
                </div>
                <div className="rounded-xl px-3 py-2 bg-muted">
                  <span className="flex gap-1">
                    <span className="w-1.5 h-1.5 rounded-full bg-muted-foreground animate-bounce [animation-delay:0ms]" />
                    <span className="w-1.5 h-1.5 rounded-full bg-muted-foreground animate-bounce [animation-delay:150ms]" />
                    <span className="w-1.5 h-1.5 rounded-full bg-muted-foreground animate-bounce [animation-delay:300ms]" />
                  </span>
                </div>
              </div>
            )}

            <div ref={bottomRef} />
          </div>

          <form onSubmit={handleSubmit} className="px-4 py-3 border-t shrink-0 flex gap-2">
            <Input
              value={input}
              onChange={(e) => setInput(e.target.value)}
              placeholder="Ask a question…"
              disabled={loading}
              className="flex-1"
              autoComplete="off"
            />
            <Button type="submit" size="icon" disabled={loading || !input.trim()}>
              <Send className="h-4 w-4" />
            </Button>
          </form>
        </SheetContent>
      </Sheet>
    </>
  );
}