"use client";

import { useState, useRef, useEffect } from "react";
import { useParams } from "next/navigation";
import { Loader2, Send, Sparkles, Bot, User } from "lucide-react";

import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";

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

export default function AIPage() {
  const params = useParams();
  const workspaceSlug = params.workspaceSlug as string;

  const [messages, setMessages] = useState<Message[]>([]);
  const [input, setInput] = useState("");
  const [isLoading, setIsLoading] = useState(false);
  const scrollRef = useRef<HTMLDivElement>(null);
  const inputRef = useRef<HTMLTextAreaElement>(null);

  // Auto-scroll on new messages
  useEffect(() => {
    if (scrollRef.current) {
      scrollRef.current.scrollTop = scrollRef.current.scrollHeight;
    }
  }, [messages]);

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

    const userMsg: Message = { id: crypto.randomUUID(), role: "user", content: trimmed };
    setMessages((prev) => [...prev, userMsg]);
    setInput("");
    setIsLoading(true);

    // Placeholder AI response
    setTimeout(() => {
      const assistantMsg: Message = {
        id: crypto.randomUUID(),
        role: "assistant",
        content:
          "I'm your AI assistant. Full AI integration is coming soon! I'll be able to help you create tasks, documents, and manage your workspace.",
      };
      setMessages((prev) => [...prev, assistantMsg]);
      setIsLoading(false);
    }, 1000);
  };

  return (
    <div className="flex h-full min-h-0 flex-col">
      {/* Header */}
      <div className="flex shrink-0 items-center gap-3 border-b px-6 py-4">
        <div className="flex h-9 w-9 items-center justify-center rounded-lg bg-primary/10">
          <Sparkles className="size-5 text-primary" />
        </div>
        <div>
          <h1 className="text-lg font-semibold">AI Assistant</h1>
          <p className="text-xs text-muted-foreground">Ask me anything about your workspace</p>
        </div>
      </div>

      {/* Messages */}
      <div ref={scrollRef} className="min-h-0 flex-1 overflow-y-auto">
        {messages.length === 0 ? (
          <div className="flex h-full min-h-[12rem] flex-col items-center justify-center gap-4 text-muted-foreground">
            <div className="flex h-16 w-16 items-center justify-center rounded-2xl bg-primary/10">
              <Bot className="size-8 text-primary" />
            </div>
            <div className="text-center">
              <p className="text-base font-medium">How can I help you today?</p>
              <p className="mt-1 text-sm">
                Ask me to create tasks, summarize documents, or manage your workspace.
              </p>
            </div>
            <div className="mt-2 flex flex-wrap justify-center gap-2">
              {["Create a new project", "Summarize my tasks", "Help me plan a sprint"].map(
                (suggestion) => (
                  <button
                    key={suggestion}
                    type="button"
                    onClick={() => setInput(suggestion)}
                    className="rounded-full border px-3 py-1.5 text-xs transition-colors hover:bg-muted"
                  >
                    {suggestion}
                  </button>
                ),
              )}
            </div>
          </div>
        ) : (
          <div className="mx-auto max-w-3xl space-y-4 px-4 py-6">
            {messages.map((msg) => (
              <div
                key={msg.id}
                className={cn("flex gap-3", msg.role === "user" && "flex-row-reverse")}
              >
                <div
                  className={cn(
                    "flex h-8 w-8 shrink-0 items-center justify-center rounded-full",
                    msg.role === "user" ? "bg-primary text-primary-foreground" : "bg-muted",
                  )}
                >
                  {msg.role === "user" ? <User className="size-4" /> : <Bot className="size-4" />}
                </div>
                <div
                  className={cn(
                    "max-w-[80%] rounded-xl px-4 py-2.5 text-sm",
                    msg.role === "user"
                      ? "bg-primary text-primary-foreground"
                      : "bg-muted",
                  )}
                >
                  {msg.content}
                </div>
              </div>
            ))}
            {isLoading && (
              <div className="flex gap-3">
                <div className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-muted">
                  <Bot className="size-4" />
                </div>
                <div className="rounded-xl bg-muted px-4 py-2.5">
                  <Loader2 className="size-4 animate-spin" />
                </div>
              </div>
            )}
          </div>
        )}
      </div>

      {/* Input */}
      <div className="shrink-0 border-t bg-background p-4">
        <form onSubmit={handleSubmit} className="mx-auto flex max-w-3xl gap-2">
          <textarea
            ref={inputRef}
            value={input}
            onChange={(e) => setInput(e.target.value)}
            onKeyDown={(e) => {
              if (e.key === "Enter" && !e.shiftKey) {
                e.preventDefault();
                void handleSubmit(e);
              }
            }}
            placeholder="Ask anything..."
            className="flex-1 resize-none rounded-lg border bg-background px-4 py-2.5 text-sm focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring"
            rows={1}
          />
          <Button type="submit" size="icon" disabled={!input.trim() || isLoading}>
            <Send className="size-4" />
          </Button>
        </form>
      </div>
    </div>
  );
}
