"use client";

import { useEffect, useState } from "react";
import { Send, Sparkles } from "lucide-react";

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

const SUGGESTIONS = [
  "Why is the LLM stage tiered B instead of A?",
  "Walk me through the End-of-Speech Pop risk on Avatar.",
  "What would it take to fix the Failure 3 cascade?",
];

export default function ExpertChat({
  selectedNodeId,
  seedQuestion,
  onSeedConsumed,
}: {
  selectedNodeId: string | null;
  seedQuestion?: string | null;
  onSeedConsumed?: () => void;
}) {
  const [messages, setMessages] = useState<ChatMessage[]>([]);
  const [input, setInput] = useState("");
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  async function send(text?: string) {
    const content = (text ?? input).trim();
    if (!content || loading) return;

    const next = [...messages, { role: "user" as const, content }];
    setMessages(next);
    setInput("");
    setLoading(true);
    setError(null);

    try {
      const res = await fetch("/api/expert", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ messages: next, selectedNodeId }),
      });
      const data = await res.json();
      if (!res.ok) throw new Error(data.error || "Request failed");
      setMessages([...next, { role: "assistant", content: data.text }]);
    } catch (err) {
      setError(err instanceof Error ? err.message : "Something went wrong.");
    } finally {
      setLoading(false);
    }
  }

  useEffect(() => {
    if (!seedQuestion) return;
    send(seedQuestion);
    onSeedConsumed?.();
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [seedQuestion]);

  return (
    <div className="flex flex-col h-full">
      <div className="flex-1 overflow-y-auto p-4 flex flex-col gap-3">
        {messages.length === 0 && (
          <div className="flex flex-col gap-2">
            <div className="flex items-center gap-2 text-sm text-[var(--muted)]">
              <Sparkles size={14} className="text-[var(--accent-teal)]" />
              Samantha audits this pipeline against 5 failure modes: Uncanny Valley,
              End-of-Speech Pop, Cascaded Latency, VRAM Death, and the VASA-1 Problem.
            </div>
            <div className="flex flex-col gap-1.5 mt-2">
              {SUGGESTIONS.map((s) => (
                <button
                  key={s}
                  onClick={() => send(s)}
                  className="text-left text-xs text-[var(--muted)] border border-[var(--panel-border)] rounded-lg px-2.5 py-2 hover:text-white hover:border-white/20 transition"
                >
                  {s}
                </button>
              ))}
            </div>
          </div>
        )}

        {messages.map((m, i) => (
          <div
            key={i}
            className={`text-sm rounded-lg px-3 py-2 max-w-[92%] whitespace-pre-wrap ${
              m.role === "user"
                ? "self-end bg-[var(--accent-blue)]/20 border border-[var(--accent-blue)]/30"
                : "self-start glass-panel"
            }`}
          >
            {m.content}
          </div>
        ))}

        {loading && (
          <div className="self-start text-xs text-[var(--muted)] px-3">Thinking…</div>
        )}
        {error && (
          <div className="self-start text-xs text-red-300/90 px-3">{error}</div>
        )}
      </div>

      <div className="p-3 border-t border-[var(--panel-border)]">
        <div className="glass-pill rounded-xl px-3 py-2 flex items-center gap-2">
          <input
            value={input}
            onChange={(e) => setInput(e.target.value)}
            onKeyDown={(e) => e.key === "Enter" && send()}
            placeholder="Ask Samantha…"
            className="flex-1 bg-transparent outline-none text-sm placeholder:text-[var(--muted)]"
          />
          <button
            onClick={() => send()}
            disabled={loading}
            className="accent-send size-7 rounded-full flex items-center justify-center text-white disabled:opacity-50"
            aria-label="Send"
          >
            <Send size={13} />
          </button>
        </div>
      </div>
    </div>
  );
}