import { useState, useCallback } from "react";
import { RotateCcw, AlertTriangle } from "lucide-react";
import { useLLM } from "../hooks/useLLM";
import { ImageUpload } from "./ImageUpload";
import { ExampleGallery } from "./ExampleGallery";
import { DetectionOverlay } from "./DetectionOverlay";
import { ResultPanel } from "./ResultPanel";
import { urlToDataUrl } from "../utils/image-utils";
import { DEFAULT_DETECTION_PROMPT } from "../utils/coco-examples";

export function DetectionApp() {
  const { detect, isGenerating, tps, dtype, result, stop } = useLLM();
  const [currentImage, setCurrentImage] = useState<string | null>(null);
  const [prompt, setPrompt] = useState(DEFAULT_DETECTION_PROMPT);
  const [loading, setLoading] = useState(false);

  const handleImageSelect = useCallback(
    (dataUrl: string) => {
      if (!dataUrl) {
        setCurrentImage(null);
        return;
      }
      setCurrentImage(dataUrl);
      detect(dataUrl, prompt);
    },
    [detect, prompt],
  );

  const handleExampleSelect = useCallback(
    async (url: string, examplePrompt: string) => {
      setLoading(true);
      try {
        const dataUrl = await urlToDataUrl(url);
        setCurrentImage(dataUrl);
        setPrompt(examplePrompt);
        detect(dataUrl, examplePrompt);
      } catch (err) {
        console.error("[Gemma4] Failed to load example:", err);
        alert(`Failed to load example image (likely CORS):\n${err instanceof Error ? err.message : String(err)}`);
      }
      setLoading(false);
    },
    [detect],
  );

  const handleRetry = useCallback(() => {
    if (currentImage) {
      detect(currentImage, prompt);
    }
  }, [currentImage, prompt, detect]);

  return (
    <div className="flex flex-col h-full bg-[#0a0a0a] text-white animate-fade-in">
      {/* Header */}
      <header className="flex items-center justify-between px-4 py-3 sm:px-6 border-b border-white/10">
        <span className="text-sm font-medium tracking-tight">Gemma 4</span>

        <div className="flex items-center gap-2">
          {isGenerating && (
            <button
              onClick={stop}
              className="px-3 py-1.5 text-xs font-medium rounded-lg bg-red-500/10 text-red-400 hover:bg-red-500/20 transition-colors cursor-pointer"
            >
              Stop
            </button>
          )}
          {currentImage && !isGenerating && (
            <button
              onClick={handleRetry}
              className="p-1.5 rounded-lg hover:bg-white/5 transition-colors text-white/60 hover:text-white cursor-pointer"
              title="Retry detection"
            >
              <RotateCcw className="h-4 w-4" />
            </button>
          )}
        </div>
      </header>

      {/* Main content */}
      <div className="flex-1 overflow-y-auto p-4 sm:p-6">
        <div className="max-w-4xl mx-auto space-y-6">
          {/* q4 slow-path warning */}
          {dtype === "q4" && (
            <div className="flex items-start gap-3 rounded-xl border border-amber-500/40 bg-amber-500/10 p-3 text-sm text-amber-200">
              <AlertTriangle className="h-5 w-5 shrink-0 mt-0.5 text-amber-400" />
              <div>
                <p className="font-medium">Running on q4 (slow path) — inference may fail with OOM on 8GB GPUs.</p>
                <p className="mt-1 text-amber-200/70 text-xs leading-relaxed">
                  For faster, stabler inference, enable{" "}
                  <code className="font-mono bg-amber-500/20 px-1 rounded">chrome://flags/#enable-unsafe-webgpu</code> and{" "}
                  <code className="font-mono bg-amber-500/20 px-1 rounded">chrome://flags/#enable-vulkan</code>, then fully restart Chrome.
                </p>
              </div>
            </div>
          )}

          {/* Prompt input */}
          <div>
            <label className="block text-sm font-medium text-white/60 mb-2">
              Prompt
            </label>
            <textarea
              value={prompt}
              onChange={(e) => setPrompt(e.target.value)}
              rows={2}
              disabled={isGenerating}
              className="w-full rounded-xl border border-white/10 bg-white/5 px-4 py-3 text-sm text-white placeholder-white/30 focus:border-[#1a73e8] focus:outline-none focus:ring-1 focus:ring-[#1a73e8] resize-none disabled:opacity-50"
              placeholder="Enter your prompt..."
            />
          </div>

          {/* Image area */}
          {currentImage ? (
            <div className="space-y-4">
              {result && result.detections.length > 0 ? (
                <DetectionOverlay
                  imageUrl={currentImage}
                  detections={result.detections}
                />
              ) : (
                <img
                  src={currentImage}
                  alt="Uploaded"
                  className="w-full max-h-[500px] object-contain rounded-xl border border-white/10"
                />
              )}

              <ResultPanel
                result={result}
                isGenerating={isGenerating}
                tps={tps}
              />

              {!isGenerating && (
                <button
                  onClick={() => setCurrentImage(null)}
                  className="w-full py-3 rounded-xl border border-white/10 text-sm font-medium text-white/60 hover:text-white hover:border-white/30 transition-colors cursor-pointer"
                >
                  Try another image
                </button>
              )}
            </div>
          ) : (
            <div className="space-y-6">
              <ImageUpload
                onImageSelect={handleImageSelect}
                currentImage={null}
                disabled={isGenerating || loading}
              />
              <ExampleGallery
                onSelect={handleExampleSelect}
                disabled={isGenerating || loading}
              />
            </div>
          )}
        </div>
      </div>
    </div>
  );
}