"use client";
import { useState, useRef, useEffect } from "react";
import { chatWithCopilot } from "../../lib/api";

const CHAT_ENDPOINT =
  process.env.NEXT_PUBLIC_CHAT_API_URL || "https://fc39539f7cb9.ngrok-free.app";

export function ChatbotPanel() {
  const [messages, setMessages] = useState<
    {
      role: "user" | "assistant";
      content: string;
      pending?: boolean;
      error?: boolean;
    }[]
  >([
    {
      role: "assistant",
      content:
        "Hi! I'm GDPR bot. Ask me about compliance, GDPR articles, or dataset risks.",
    },
  ]);
  const [input, setInput] = useState("");
  const [isLoading, setIsLoading] = useState(false);
  const [delayedError, setDelayedError] = useState<string | null>(null);
  const scrollRef = useRef<HTMLDivElement | null>(null);

  useEffect(() => {
    if (scrollRef.current) {
      scrollRef.current.scrollTop = scrollRef.current.scrollHeight;
    }
  }, [messages]);

  async function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    const prompt = input.trim();
    if (!prompt || isLoading) return;
    setInput("");
    setDelayedError(null);
    setMessages((prev) => [
      ...prev,
      { role: "user", content: prompt },
      { role: "assistant", content: "Thinking…", pending: true },
    ]);
    setIsLoading(true);

    // Delay window for showing errors (avoid instant flashing if slow model)
    const errorDisplayDelayMs = 4_000;
    let canShowError = false;
    const delayTimer = setTimeout(() => {
      canShowError = true;
      if (delayedError) showErrorBubble(delayedError);
    }, errorDisplayDelayMs);

    function showErrorBubble(msg: string) {
      setMessages((prev) =>
        prev.map((m) =>
          m.pending ? { ...m, content: msg, pending: false, error: true } : m,
        ),
      );
    }

    try {
      let responseText: string | null = null;
      // Primary attempt via shared client
      try {
        responseText = await chatWithCopilot(prompt);
      } catch (primaryErr: any) {
        // Fallback: replicate working curl (query param, empty body)
        try {
          const res = await fetch(
            `${CHAT_ENDPOINT}/chat?prompt=${encodeURIComponent(prompt)}`,
            {
              method: "POST",
              headers: { accept: "application/json" },
              body: "",
            },
          );
          if (res.ok) {
            const j = await res.json();
            responseText = j.response || JSON.stringify(j);
          } else {
            throw primaryErr;
          }
        } catch {
          throw primaryErr;
        }
      }
      clearTimeout(delayTimer);
      setMessages((prev) =>
        prev.map((m) =>
          m.pending
            ? {
                ...m,
                content: responseText || "No response text",
                pending: false,
              }
            : m,
        ),
      );
    } catch (err: any) {
      clearTimeout(delayTimer);
      const errMsg = err?.message || "Unexpected error";
      if (canShowError) {
        showErrorBubble(errMsg);
      } else {
        setDelayedError(errMsg);
      }
    } finally {
      setIsLoading(false);
    }
  }

  return (
    <div className="flex flex-col h-full border-l border-slate-200 bg-white/80 overflow-hidden">
      <div className="h-14 flex items-center px-4 border-b border-slate-200">
        <h2 className="font-semibold text-sm text-brand-700">GDPR Bot</h2>
      </div>
      <div ref={scrollRef} className="flex-1 overflow-y-auto p-4 space-y-3">
        {messages.map((m, i) => (
          <div
            key={i}
            className={
              "rounded-md px-3 py-2 text-sm max-w-[80%] whitespace-pre-wrap " +
              (m.role === "assistant"
                ? m.error
                  ? "bg-red-50 text-red-700 border border-red-200"
                  : m.pending
                    ? "bg-brand-600/10 text-brand-700 animate-pulse"
                    : "bg-brand-600/10 text-brand-800"
                : "bg-brand-600 text-white ml-auto")
            }
          >
            {m.content}
          </div>
        ))}
      </div>
      <div className="p-3 border-t border-slate-200">
        <form className="flex gap-2" onSubmit={handleSubmit}>
          <input
            value={input}
            onChange={(e) => setInput(e.target.value)}
            placeholder="Ask about GDPR, compliance, privacy risks..."
            className="flex-1 rounded-md border border-slate-300 bg-white px-3 py-2 text-sm focus:outline-none focus:ring-2 focus:ring-brand-400 disabled:opacity-60"
            disabled={isLoading}
          />
          <button
            type="submit"
            disabled={!input.trim() || isLoading}
            className="rounded-md bg-brand-600 text-white px-4 py-2 text-sm font-medium disabled:opacity-50"
          >
            {isLoading ? "Sending…" : "Send"}
          </button>
        </form>
        <p className="mt-2 text-[11px] text-slate-500">
          Responses may take up to 1–2 minutes while the local model generates
          output.
        </p>
      </div>
    </div>
  );
}
