frontend/src/components/DocumentsPanel.jsx

import React, { useState } from 'react';
import { Plus, FileText, CheckCircle, Loader2, Search, Globe, BookOpen, Download } from 'lucide-react';
import { ingestPDF, searchPapers, importPaper } from '../api';

const DocumentsPanel = ({ documents, setDocuments, notebookId }) => {
    const [activeTab, setActiveTab] = useState('sources'); // sources, search
    const [isUploading, setIsUploading] = useState(false);

    // Search State
    const [searchQuery, setSearchQuery] = useState('');
    const [searchMode, setSearchMode] = useState('academic'); // academic, web
    const [searchResults, setSearchResults] = useState([]);
    const [isSearching, setIsSearching] = useState(false);
    const [importingIds, setImportingIds] = useState({});

    // Hidden file input handler
    const handleFileUpload = async (e) => {
        const file = e.target.files[0];
        if (!file) return;

        setIsUploading(true);
        try {
            const result = await ingestPDF(file, notebookId);
            setDocuments(prev => [{
                id: result.paper_id,
                title: file.name,
                date: new Date().toLocaleDateString(),
                active: true,
                filename: file.name
            }, ...prev]);
        } catch (error) {
            console.error("Upload failed", error);
            alert("Failed to upload paper");
        } finally {
            setIsUploading(false);
        }
    };

    const handleSearch = async (e) => {
        e.preventDefault();
        if (!searchQuery.trim()) return;

        setIsSearching(true);
        try {
            const results = await searchPapers(searchQuery, searchMode);
            setSearchResults(results);
        } catch (error) {
            console.error("Search failed", error);
        } finally {
            setIsSearching(false);
        }
    };

    const handleImport = async (paper) => {
        setImportingIds(prev => ({ ...prev, [paper.id]: true }));
        try {
            const result = await importPaper(notebookId, paper);
            setDocuments(prev => [{
                id: result.doc_id,
                title: paper.title,
                date: new Date().toLocaleDateString(),
                active: true,
                filename: paper.title + ".txt"
            }, ...prev]);
            // Switch back to sources list to see the new file
            setActiveTab('sources');
        } catch (error) {
            console.error("Import failed", error);
            alert("Failed to import paper");
        } finally {
            setImportingIds(prev => ({ ...prev, [paper.id]: false }));
        }
    };

    return (
        <div className="h-full flex flex-col border-r border-slate-200 bg-[#f8f9fa]">
            {/* Tabs */}
            <div className="flex border-b border-slate-200 bg-white">
                <button
                    onClick={() => setActiveTab('sources')}
                    className={`flex-1 py-3 text-sm font-medium ${activeTab === 'sources' ? 'text-blue-600 border-b-2 border-blue-600' : 'text-slate-500 hover:text-slate-700'}`}
                >
                    Sources
                </button>
                <button
                    onClick={() => setActiveTab('search')}
                    className={`flex-1 py-3 text-sm font-medium ${activeTab === 'search' ? 'text-blue-600 border-b-2 border-blue-600' : 'text-slate-500 hover:text-slate-700'}`}
                >
                    Add Source
                </button>
            </div>

            {/* TAB: SOURCES */}
            {activeTab === 'sources' && (
                <div className="flex-1 flex flex-col p-4 overflow-hidden">
                    <div className="mb-6">
                        <label className="flex items-center gap-2 w-full p-3 rounded-full border border-slate-300 hover:bg-white hover:shadow-sm cursor-pointer transition-all group bg-white">
                            <div className="bg-slate-100 p-1 rounded-full group-hover:bg-slate-200">
                                {isUploading ? <Loader2 size={16} className="animate-spin text-slate-600" /> : <Plus size={16} className="text-slate-600" />}
                            </div>
                            <span className="text-sm font-medium text-slate-700">Upload PDF</span>
                            <input type="file" accept=".pdf" className="hidden" onChange={handleFileUpload} disabled={isUploading} />
                        </label>
                    </div>

                    <div className="flex-1 overflow-y-auto space-y-2">
                        {documents.map((doc) => (
                            <div key={doc.id} className="group flex items-start gap-3 p-3 rounded-xl hover:bg-white hover:shadow-sm transition-all cursor-pointer border border-transparent hover:border-slate-200">
                                <div className="mt-1">
                                    <div className="w-8 h-8 rounded-lg bg-orange-50 flex items-center justify-center border border-orange-100 text-orange-600">
                                        <FileText size={16} />
                                    </div>
                                </div>
                                <div className="flex-1 min-w-0">
                                    <h3 className="text-sm font-medium text-slate-800 truncate leading-snug">
                                        {doc.title || doc.filename}
                                    </h3>
                                    <p className="text-xs text-slate-400 mt-1">
                                        {doc.date || (doc.uploaded_at ? new Date(doc.uploaded_at * 1000).toLocaleDateString() : 'Just now')}
                                    </p>
                                </div>
                                {doc.active && <CheckCircle size={14} className="text-blue-500 mt-1" />}
                            </div>
                        ))}
                        {documents.length === 0 && (
                            <div className="text-center mt-10 p-4">
                                <p className="text-sm text-slate-400">No sources added.</p>
                            </div>
                        )}
                    </div>
                </div>
            )}

            {/* TAB: SEARCH */}
            {activeTab === 'search' && (
                <div className="flex-1 flex flex-col p-4 overflow-hidden">
                    <form onSubmit={handleSearch} className="mb-4 space-y-3">
                        <div className="flex bg-slate-200 p-1 rounded-lg">
                            <button type="button" onClick={() => setSearchMode('academic')} className={`flex-1 text-xs font-medium py-1.5 rounded-md transition-all ${searchMode === 'academic' ? 'bg-white shadow-sm text-slate-900' : 'text-slate-500'}`}>Academic</button>
                            <button type="button" onClick={() => setSearchMode('web')} className={`flex-1 text-xs font-medium py-1.5 rounded-md transition-all ${searchMode === 'web' ? 'bg-white shadow-sm text-slate-900' : 'text-slate-500'}`}>Web</button>
                        </div>
                        <div className="relative">
                            <Search className="absolute left-3 top-2.5 text-slate-400" size={16} />
                            <input
                                type="text"
                                placeholder={searchMode === 'academic' ? "Search papers..." : "Search web..."}
                                className="w-full pl-9 pr-4 py-2 bg-white border border-slate-200 rounded-lg text-sm focus:outline-none focus:ring-2 focus:ring-blue-500"
                                value={searchQuery}
                                onChange={(e) => setSearchQuery(e.target.value)}
                            />
                        </div>
                        <button type="submit" disabled={isSearching} className="w-full py-2 bg-blue-600 text-white rounded-lg text-sm font-medium hover:bg-blue-700 disabled:opacity-50">
                            {isSearching ? 'Searching...' : 'Find Sources'}
                        </button>
                    </form>

                    <div className="flex-1 overflow-y-auto space-y-4 pr-1">
                        {searchResults.map((result) => (
                            <div key={result.id} className="bg-white p-3 rounded-xl border border-slate-200 shadow-sm">
                                <h3 className="text-sm font-bold text-slate-900 leading-tight mb-1 line-clamp-2">
                                    <a href={result.url} target="_blank" rel="noopener noreferrer" className="hover:underline">{result.title}</a>
                                </h3>
                                <p className="text-xs text-slate-500 mb-2">{result.venue} • {result.year}</p>
                                <p className="text-xs text-slate-600 mb-3 line-clamp-3">{result.abstract}</p>
                                <div className="flex items-center justify-between">
                                    <span className="text-[10px] bg-slate-100 px-2 py-1 rounded text-slate-500 font-medium border border-slate-200">
                                        Cited by {(result.citations || 0).toLocaleString()}
                                    </span>
                                    <button
                                        onClick={() => handleImport(result)}
                                        disabled={importingIds[result.id]}
                                        className="flex items-center gap-1.5 px-3 py-1.5 bg-slate-900 text-white text-xs font-medium rounded-lg hover:bg-slate-800 disabled:opacity-50"
                                    >
                                        {importingIds[result.id] ? <Loader2 size={12} className="animate-spin" /> : <Download size={12} />}
                                        Import
                                    </button>
                                </div>
                            </div>
                        ))}
                    </div>
                </div>
            )}
        </div>
    );
};

export default DocumentsPanel;