import { useEffect, useState, useCallback } from 'react';
import { api, type ClientDocument } from '@/lib/api';
import { FileText, Upload, Trash2, Download, File, FileImage, FileSpreadsheet, Filter } from 'lucide-react';
import { formatDate } from '@/lib/utils';

const CATEGORIES = [
  { value: '', label: 'All' },
  { value: 'contract', label: 'Contract' },
  { value: 'agreement', label: 'Agreement' },
  { value: 'id', label: 'ID Copy' },
  { value: 'statement', label: 'Statement' },
  { value: 'correspondence', label: 'Correspondence' },
  { value: 'other', label: 'Other' },
];

const categoryColors: Record<string, string> = {
  contract: 'bg-blue-100 text-blue-700 dark:bg-blue-900/30 dark:text-blue-300',
  agreement: 'bg-purple-100 text-purple-700 dark:bg-purple-900/30 dark:text-purple-300',
  id: 'bg-amber-100 text-amber-700 dark:bg-amber-900/30 dark:text-amber-300',
  statement: 'bg-green-100 text-green-700 dark:bg-green-900/30 dark:text-green-300',
  correspondence: 'bg-pink-100 text-pink-700 dark:bg-pink-900/30 dark:text-pink-300',
  other: 'bg-slate-100 text-slate-700 dark:bg-slate-700 dark:text-slate-300',
};

function fileIcon(mimeType: string) {
  if (mimeType.startsWith('image/')) return <FileImage className="w-5 h-5 text-pink-500" />;
  if (mimeType.includes('spreadsheet') || mimeType.includes('csv') || mimeType.includes('excel'))
    return <FileSpreadsheet className="w-5 h-5 text-green-500" />;
  if (mimeType.includes('pdf')) return <FileText className="w-5 h-5 text-red-500" />;
  return <File className="w-5 h-5 text-slate-400" />;
}

function formatSize(bytes: number): string {
  if (bytes < 1024) return `${bytes} B`;
  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`;
}

export default function ClientDocuments({ clientId }: { clientId: string }) {
  const [documents, setDocuments] = useState<ClientDocument[]>([]);
  const [loading, setLoading] = useState(true);
  const [uploading, setUploading] = useState(false);
  const [category, setCategory] = useState('');
  const [dragOver, setDragOver] = useState(false);
  const [uploadCategory, setUploadCategory] = useState('other');

  const fetchDocs = useCallback(async () => {
    try {
      const docs = await api.getClientDocuments(clientId, category || undefined);
      setDocuments(docs);
    } catch { /* silently handled */ }
    setLoading(false);
  }, [clientId, category]);

  // eslint-disable-next-line react-hooks/set-state-in-effect
  useEffect(() => { fetchDocs(); }, [fetchDocs]);

  const handleUpload = async (files: FileList | File[]) => {
    setUploading(true);
    try {
      for (const file of Array.from(files)) {
        await api.uploadDocument(clientId, file, { category: uploadCategory });
      }
      await fetchDocs();
    } catch (e: unknown) {
      alert(e instanceof Error ? e.message : 'Upload failed');
    }
    setUploading(false);
  };

  const handleDrop = (e: React.DragEvent) => {
    e.preventDefault();
    setDragOver(false);
    if (e.dataTransfer.files.length) handleUpload(e.dataTransfer.files);
  };

  const handleDelete = async (docId: string) => {
    if (!confirm('Delete this document?')) return;
    try {
      await api.deleteDocument(docId);
      setDocuments(prev => prev.filter(d => d.id !== docId));
    } catch { /* silently handled */ }
  };

  const handleDownload = (docId: string, name: string) => {
    const token = localStorage.getItem('network-auth-token');
    const url = api.getDocumentDownloadUrl(docId);
    // Use fetch with auth header then download
    fetch(url, {
      headers: token ? { Authorization: `Bearer ${token}` } : {},
      credentials: 'include',
    })
      .then(r => r.blob())
      .then(blob => {
        const a = document.createElement('a');
        a.href = URL.createObjectURL(blob);
        a.download = name;
        a.click();
        URL.revokeObjectURL(a.href);
      });
  };

  return (
    <div className="space-y-4">
      {/* Upload Area */}
      <div
        onDrop={handleDrop}
        onDragOver={e => { e.preventDefault(); setDragOver(true); }}
        onDragLeave={() => setDragOver(false)}
        className={`border-2 border-dashed rounded-xl p-8 text-center transition-colors ${
          dragOver
            ? 'border-blue-400 bg-blue-50 dark:bg-blue-900/20'
            : 'border-slate-300 dark:border-slate-600 hover:border-blue-300 dark:hover:border-blue-500'
        }`}
      >
        <Upload className="w-8 h-8 mx-auto text-slate-400 mb-2" />
        <p className="text-sm text-slate-600 dark:text-slate-300 mb-2">
          {uploading ? 'Uploading...' : 'Drag & drop files here, or click to browse'}
        </p>
        <div className="flex items-center justify-center gap-3">
          <select
            value={uploadCategory}
            onChange={e => setUploadCategory(e.target.value)}
            className="text-xs px-2 py-1 border border-slate-300 dark:border-slate-600 rounded bg-white dark:bg-slate-800 text-slate-700 dark:text-slate-300"
          >
            {CATEGORIES.filter(c => c.value).map(c => (
              <option key={c.value} value={c.value}>{c.label}</option>
            ))}
          </select>
          <label className="cursor-pointer px-4 py-2 bg-blue-600 text-white text-sm rounded-lg hover:bg-blue-700 transition-colors">
            Browse Files
            <input
              type="file"
              multiple
              className="hidden"
              onChange={e => e.target.files && handleUpload(e.target.files)}
              disabled={uploading}
            />
          </label>
        </div>
      </div>

      {/* Category Filter */}
      <div className="flex items-center gap-2">
        <Filter className="w-4 h-4 text-slate-400" />
        <div className="flex gap-1.5 flex-wrap">
          {CATEGORIES.map(c => (
            <button
              key={c.value}
              onClick={() => setCategory(c.value)}
              className={`px-2.5 py-1 rounded-full text-xs font-medium transition-colors ${
                category === c.value
                  ? 'bg-blue-600 text-white'
                  : 'bg-slate-100 dark:bg-slate-700 text-slate-600 dark:text-slate-300 hover:bg-slate-200 dark:hover:bg-slate-600'
              }`}
            >
              {c.label}
            </button>
          ))}
        </div>
      </div>

      {/* Document List */}
      <div className="bg-white dark:bg-slate-800 border border-slate-200 dark:border-slate-700 rounded-xl divide-y divide-slate-100 dark:divide-slate-700">
        {loading ? (
          <p className="px-5 py-8 text-center text-sm text-slate-400">Loading...</p>
        ) : documents.length === 0 ? (
          <p className="px-5 py-8 text-center text-sm text-slate-400">No documents uploaded yet</p>
        ) : (
          documents.map(doc => (
            <div key={doc.id} className="flex items-center gap-3 px-5 py-3">
              {fileIcon(doc.mimeType)}
              <div className="flex-1 min-w-0">
                <p className="text-sm font-medium text-slate-900 dark:text-slate-100 truncate">{doc.name}</p>
                <div className="flex items-center gap-2 mt-0.5">
                  <span className={`px-1.5 py-0.5 rounded text-xs font-medium ${categoryColors[doc.category] || categoryColors.other}`}>
                    {doc.category}
                  </span>
                  <span className="text-xs text-slate-400">{formatSize(doc.size)}</span>
                  <span className="text-xs text-slate-400">{formatDate(doc.createdAt)}</span>
                </div>
                {doc.notes && <p className="text-xs text-slate-500 dark:text-slate-400 mt-0.5 truncate">{doc.notes}</p>}
              </div>
              <button
                onClick={() => handleDownload(doc.id, doc.name)}
                className="p-2 rounded-lg text-slate-400 hover:bg-slate-100 dark:hover:bg-slate-700 hover:text-blue-600 transition-colors"
                title="Download"
              >
                <Download className="w-4 h-4" />
              </button>
              <button
                onClick={() => handleDelete(doc.id)}
                className="p-2 rounded-lg text-slate-400 hover:bg-red-50 dark:hover:bg-red-900/20 hover:text-red-600 transition-colors"
                title="Delete"
              >
                <Trash2 className="w-4 h-4" />
              </button>
            </div>
          ))
        )}
      </div>
    </div>
  );
}