'use client';

import { useState, useEffect, useRef, useCallback, DragEvent, ChangeEvent } from 'react';
import { useApiKey } from '@/components/shared/ApiKeyWidget/apikey-context';
import { Section } from '@/components/shared/Section';
import { CodeExamplesWidget } from '@/components/demo/CodeExamplesWidget';
import { SelectedFileCodePreview } from '@/components/demo/SelectedFileCodePreview';
import { ImageMetadataBar } from '@/components/shared/ImageMetadataBar';
import { ImageCard } from '@/components/shared/ImageCard';
import { calculateAspectRatio } from '@/utils/imageUtils';

const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:3000';
const UPLOAD_HISTORY_KEY = 'banatie_upload_history';

const ALLOWED_FILE_TYPES = ['image/png', 'image/jpeg', 'image/jpg', 'image/webp'];
const MAX_FILE_SIZE = 5 * 1024 * 1024; // 5MB

interface UploadResponse {
  success: boolean;
  message: string;
  data?: {
    filename: string;
    originalName: string;
    path: string;
    url: string;
    size: number;
    contentType: string;
    uploadedAt: string;
  };
  error?: string;
}

interface UploadHistoryItem {
  id: string;
  timestamp: Date;
  filename: string;
  originalName: string;
  url: string;
  size: number;
  contentType: string;
  durationMs: number;
  width?: number;
  height?: number;
  aspectRatio?: string;
  downloadMs?: number;
}

export default function DemoUploadPage() {
  // API Key from context
  const { apiKey, apiKeyValidated, focus } = useApiKey();

  // Upload State
  const [selectedFile, setSelectedFile] = useState<File | null>(null);
  const [previewUrl, setPreviewUrl] = useState<string | null>(null);
  const [uploading, setUploading] = useState(false);
  const [uploadError, setUploadError] = useState('');
  const [validationError, setValidationError] = useState('');
  const [dragActive, setDragActive] = useState(false);
  const [imageDimensions, setImageDimensions] = useState<{
    width: number;
    height: number;
    aspectRatio: string;
  } | null>(null);

  // History State
  const [uploadHistory, setUploadHistory] = useState<UploadHistoryItem[]>([]);

  // Copy Feedback State
  const [codeCopied, setCodeCopied] = useState(false);

  // Refs
  const fileInputRef = useRef<HTMLInputElement>(null);

  // Load upload history from sessionStorage
  useEffect(() => {
    const storedHistory = sessionStorage.getItem(UPLOAD_HISTORY_KEY);
    if (storedHistory) {
      try {
        const parsed = JSON.parse(storedHistory);
        setUploadHistory(
          parsed.map((item: UploadHistoryItem) => ({
            ...item,
            timestamp: new Date(item.timestamp),
          })),
        );
      } catch (error) {
        console.error('Failed to parse upload history:', error);
      }
    }
  }, []);

  // Save upload history to sessionStorage
  useEffect(() => {
    if (uploadHistory.length > 0) {
      sessionStorage.setItem(UPLOAD_HISTORY_KEY, JSON.stringify(uploadHistory));
    }
  }, [uploadHistory]);

  const validateFile = (file: File): string | null => {
    if (!ALLOWED_FILE_TYPES.includes(file.type)) {
      return `Invalid file type. Allowed: PNG, JPEG, JPG, WebP`;
    }

    if (file.size > MAX_FILE_SIZE) {
      return `File too large. Maximum size: ${MAX_FILE_SIZE / (1024 * 1024)}MB`;
    }

    return null;
  };

  const handleFileSelect = (file: File) => {
    setValidationError('');
    setUploadError('');

    const error = validateFile(file);
    if (error) {
      setValidationError(error);
      setSelectedFile(null);
      setPreviewUrl(null);
      setImageDimensions(null);
      return;
    }

    setSelectedFile(file);

    const reader = new FileReader();
    reader.onloadend = () => {
      const dataUrl = reader.result as string;
      setPreviewUrl(dataUrl);

      // Extract image dimensions
      const img = new Image();
      img.onload = () => {
        const aspectRatio = calculateAspectRatio(img.width, img.height);
        setImageDimensions({
          width: img.width,
          height: img.height,
          aspectRatio,
        });
      };
      img.src = dataUrl;
    };
    reader.readAsDataURL(file);
  };

  const handleFileInputChange = (e: ChangeEvent<HTMLInputElement>) => {
    const file = e.target.files?.[0];
    if (file) {
      handleFileSelect(file);
    }
  };

  const handleDragEnter = (e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
    setDragActive(true);
  };

  const handleDragLeave = (e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
    setDragActive(false);
  };

  const handleDragOver = (e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
  };

  const handleDrop = (e: DragEvent<HTMLDivElement>) => {
    e.preventDefault();
    e.stopPropagation();
    setDragActive(false);

    const file = e.dataTransfer.files?.[0];
    if (file) {
      handleFileSelect(file);
    }
  };

  const handleUpload = async () => {
    if (!selectedFile) return;

    setUploading(true);
    setUploadError('');
    const startTime = Date.now();

    try {
      const formData = new FormData();
      formData.append('file', selectedFile);

      const response = await fetch(`${API_BASE_URL}/api/upload`, {
        method: 'POST',
        headers: {
          'X-API-Key': apiKey,
        },
        body: formData,
      });

      const result: UploadResponse = await response.json();

      if (result.success && result.data) {
        const endTime = Date.now();
        const durationMs = endTime - startTime;

        const historyItem: UploadHistoryItem = {
          id: Date.now().toString(),
          timestamp: new Date(),
          filename: result.data.filename,
          originalName: result.data.originalName,
          url: result.data.url,
          size: result.data.size,
          contentType: result.data.contentType,
          durationMs,
          width: imageDimensions?.width,
          height: imageDimensions?.height,
          aspectRatio: imageDimensions?.aspectRatio,
        };

        setUploadHistory((prev) => [historyItem, ...prev]);

        setSelectedFile(null);
        setPreviewUrl(null);
        setImageDimensions(null);
        if (fileInputRef.current) {
          fileInputRef.current.value = '';
        }
      } else {
        setUploadError(result.error || 'Upload failed');
      }
    } catch (error) {
      setUploadError(error instanceof Error ? error.message : 'Failed to upload file');
    } finally {
      setUploading(false);
    }
  };

  const handleDownloadMeasured = useCallback((itemId: string, downloadMs: number) => {
    setUploadHistory((prev) =>
      prev.map((item) => {
        // Only update if this item doesn't have downloadMs yet (prevent re-measuring)
        if (item.id === itemId && item.downloadMs === undefined) {
          return { ...item, downloadMs };
        }
        return item;
      })
    );
  }, []);

  const generateUploadCodeExamples = (item: UploadHistoryItem, key: string, baseUrl: string) => {
    const fileName = item.originalName;

    return {
      curl: `# Navigate to your images folder
cd /your/images/folder

# Upload the file
curl -X POST "${baseUrl}/api/upload" \\
  -H "X-API-Key: ${key}" \\
  -F "file=@${fileName}"`,
      fetch: `// Set your images folder path
const imagePath = '/your/images/folder';
const fileName = '${fileName}';

// For Node.js with fs module:
const fs = require('fs');
const FormData = require('form-data');
const formData = new FormData();
formData.append('file', fs.createReadStream(\`\${imagePath}/\${fileName}\`));

fetch('${baseUrl}/api/upload', {
  method: 'POST',
  headers: {
    'X-API-Key': '${key}'
  },
  body: formData
})
  .then(response => response.json())
  .then(data => console.log(data))
  .catch(error => console.error('Error:', error));`,
      rest: `# From your images folder: /your/images/folder

POST ${baseUrl}/api/upload
Headers:
  X-API-Key: ${key}
  Content-Type: multipart/form-data

Body (form-data):
  file: @${fileName}`,
    };
  };

  const handleCopyCode = (code: string) => {
    navigator.clipboard.writeText(code);
    setCodeCopied(true);
    setTimeout(() => setCodeCopied(false), 2000);
  };

  return (
    <Section className="py-12 md:py-16 min-h-screen">
      <header className="mb-8 md:mb-12">
        <h1 className="text-3xl md:text-4xl lg:text-5xl font-bold text-white mb-3">
          File Upload Workbench
        </h1>
        <p className="text-gray-400 text-base md:text-lg">
          Developer tool for testing file upload API
        </p>
      </header>

      {/* API Key Required Notice - Only show when not validated */}
      {!apiKeyValidated && (
        <div className="mb-6 p-5 bg-amber-900/10 border border-amber-700/50 rounded-2xl">
          <div className="flex items-center justify-between flex-wrap gap-4">
            <div>
              <h3 className="text-lg font-semibold text-white mb-1">API Key Required</h3>
              <p className="text-sm text-gray-400">Enter your API key to use this workbench</p>
            </div>
            <button
              onClick={focus}
              className="px-5 py-2.5 bg-amber-600 hover:bg-amber-700 text-white font-medium rounded-lg transition-colors"
            >
              Enter API Key
            </button>
          </div>
        </div>
      )}

      <section
        className="mb-8 p-6 bg-slate-900/80 backdrop-blur-sm border border-slate-700 rounded-2xl"
        aria-label="File Upload"
      >
        <h2 className="text-lg font-semibold text-white mb-4">Upload File</h2>

        <div
          className={`relative border-2 border-dashed rounded-xl p-8 transition-all ${
            dragActive
              ? 'border-amber-500 bg-amber-500/10'
              : 'border-slate-700 hover:border-slate-600'
          } ${!apiKeyValidated || uploading ? 'opacity-50 cursor-not-allowed' : 'cursor-pointer'}`}
          onDragEnter={handleDragEnter}
          onDragLeave={handleDragLeave}
          onDragOver={handleDragOver}
          onDrop={handleDrop}
          onClick={() => {
            if (apiKeyValidated && !uploading) {
              fileInputRef.current?.click();
            }
          }}
        >
          <input
            ref={fileInputRef}
            type="file"
            accept="image/png,image/jpeg,image/jpg,image/webp"
            onChange={handleFileInputChange}
            disabled={!apiKeyValidated || uploading}
            className="hidden"
            aria-label="File input"
          />

          {!selectedFile ? (
            <div className="text-center">
              <svg
                className="w-12 h-12 mx-auto mb-4 text-gray-400"
                fill="none"
                viewBox="0 0 24 24"
                stroke="currentColor"
              >
                <path
                  strokeLinecap="round"
                  strokeLinejoin="round"
                  strokeWidth={2}
                  d="M7 16a4 4 0 01-.88-7.903A5 5 0 1115.9 6L16 6a5 5 0 011 9.9M15 13l-3-3m0 0l-3 3m3-3v12"
                />
              </svg>
              <p className="text-gray-300 mb-2">
                Drag and drop your image here, or click to browse
              </p>
              <p className="text-sm text-gray-500">PNG, JPEG, JPG, WebP up to 5MB</p>
            </div>
          ) : (
            <div className="flex flex-col items-center gap-4">
              {previewUrl && (
                <img
                  src={previewUrl}
                  alt="Preview"
                  className="max-h-64 max-w-full object-contain rounded-lg border border-slate-700"
                />
              )}
              <div className="text-center">
                <p className="text-white font-medium mb-2">{selectedFile.name}</p>
                {imageDimensions && (
                  <ImageMetadataBar
                    width={imageDimensions.width}
                    height={imageDimensions.height}
                    fileSize={selectedFile.size}
                    fileType={selectedFile.type}
                    showVisualIndicator={true}
                  />
                )}
              </div>
              <button
                onClick={(e) => {
                  e.stopPropagation();
                  setSelectedFile(null);
                  setPreviewUrl(null);
                  setImageDimensions(null);
                  if (fileInputRef.current) {
                    fileInputRef.current.value = '';
                  }
                }}
                className="text-sm text-red-400 hover:text-red-300 transition-colors"
              >
                Remove
              </button>
            </div>
          )}
        </div>

        {validationError && (
          <p className="mt-3 text-sm text-red-400" role="alert">
            {validationError}
          </p>
        )}

        {selectedFile && apiKeyValidated && !validationError && (
          <div className="mt-6">
            <SelectedFileCodePreview
              file={selectedFile}
              apiKey={apiKey}
              apiBaseUrl={API_BASE_URL}
              onCopy={handleCopyCode}
            />
          </div>
        )}

        <div className="flex items-center justify-between gap-4 flex-wrap pt-4 mt-4 border-t border-slate-700/50">
          <div className="text-sm text-gray-500">
            {uploading ? 'Uploading...' : selectedFile ? 'Ready to upload' : 'No file selected'}
          </div>
          <button
            onClick={handleUpload}
            disabled={!apiKeyValidated || uploading || !selectedFile}
            className="px-6 py-2.5 rounded-lg bg-gradient-to-r from-amber-600 to-orange-600 text-white font-semibold hover:from-amber-500 hover:to-orange-500 transition-all disabled:opacity-50 disabled:cursor-not-allowed shadow-lg shadow-amber-900/30 focus:ring-2 focus:ring-amber-500"
          >
            {uploading ? 'Uploading...' : 'Upload File'}
          </button>
        </div>

        {uploadError && (
          <p className="mt-3 text-sm text-red-400" role="alert">
            {uploadError}
          </p>
        )}
      </section>

      {uploadHistory.length > 0 && (
        <section className="space-y-6" aria-label="Upload History">
          <h2 className="text-xl md:text-2xl font-bold text-white">Upload History</h2>

          <div className="space-y-6">
            {uploadHistory.map((item) => (
              <div key={item.id} className="grid grid-cols-1 lg:grid-cols-3 gap-4">
                {/* Column 1: Image Card */}
                <div className="lg:col-span-1">
                  <ImageCard
                    imageUrl={item.url}
                    filename={item.originalName}
                    width={item.width}
                    height={item.height}
                    fileSize={item.size}
                    fileType={item.contentType}
                    timestamp={item.timestamp}
                    measureDownloadTime={true}
                    onDownloadMeasured={(downloadMs) => handleDownloadMeasured(item.id, downloadMs)}
                  />
                </div>

                {/* Columns 2-3: API Code Examples Widget */}
                <div className="lg:col-span-2">
                  <CodeExamplesWidget
                    codeExamples={generateUploadCodeExamples(item, apiKey, API_BASE_URL)}
                    onCopy={handleCopyCode}
                  />
                </div>
              </div>
            ))}
          </div>
        </section>
      )}
    </Section>
  );
}