import React, { useState, useRef, useEffect } from 'react';
import {
    Search, Bot, Loader2, FileText, ExternalLink,
    Sparkles, RefreshCw, BookOpen, ChevronRight,
    ArrowRight, Globe, Database, Brain, CheckCircle,
    AlertCircle
} from 'lucide-react';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { ScrollArea } from '@/components/ui/scroll-area';
import { Badge } from '@/components/ui/badge';
import { cn } from '@/lib/utils';
import { API_URL } from '@/config/api';
import ReactMarkdown from 'react-markdown';

interface ResearchStep {
    id: string;
    description: string;
    status: 'pending' | 'active' | 'completed' | 'failed';
    timestamp: Date;
    details?: string;
}

export default function ResearchAgentWidget() {
    const [query, setQuery] = useState('');
    const [isResearching, setIsResearching] = useState(false);
    const [steps, setSteps] = useState<ResearchStep[]>([]);
    const [streamedContent, setStreamedContent] = useState('');
    const scrollRef = useRef<HTMLDivElement>(null);

    // Auto-scroll output
    useEffect(() => {
        if (scrollRef.current) {
            // scrollRef.current.scrollTop = scrollRef.current.scrollHeight;
        }
    }, [streamedContent]);

    const addStep = (desc: string, status: ResearchStep['status'] = 'active', details?: string) => {
        setSteps(prev => {
            // Mark previous active step as completed if exists
            const newSteps = prev.map(s => 
                s.status === 'active' ? { ...s, status: 'completed' } : s
            );
            return [...newSteps, {
                id: Date.now().toString() + Math.random(),
                description: desc,
                status,
                timestamp: new Date(),
                details
            } as ResearchStep];
        });
    };

    const completeLastStep = () => {
        setSteps(prev => prev.map(s => 
            s.status === 'active' ? { ...s, status: 'completed' } : s
        ));
    };

    const failLastStep = () => {
        setSteps(prev => prev.map(s => 
            s.status === 'active' ? { ...s, status: 'failed' } : s
        ));
    };

    const startResearch = async () => {
        if (!query.trim()) return;

        setIsResearching(true);
        setSteps([]);
        setStreamedContent('');

        try {
            addStep('Initializing research agent...', 'completed');
            addStep(`Analyzing topic: "${query}"`);

            // Use the autonomous hybrid search endpoint
            // We frame it as a 'research' request which the backend should handle intelligently
            // or we use the generic query endpoint and let the agent decide
            const response = await fetch(`${API_URL}/api/mcp/autonomous/query`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({
                    type: 'research', // Hint to the router
                    params: {
                        query: query, // Common param
                        topic: query, // Specific param
                        depth: 'deep',
                        includeSources: true
                    }
                })
            });

            if (!response.ok) throw new Error(`API Error: ${response.status}`);

            // Simulate progression if not streaming (since our current API is request/response)
            // In a real websocket setup, these would be events
            setTimeout(() => {
                if (isResearching) addStep('Querying internal knowledge base...', 'active', 'Vector Search + Graph Traversal');
            }, 1000);
            
            setTimeout(() => {
                if (isResearching) addStep('Synthesizing intelligence...', 'active', 'GPU-accelerated context fusion');
            }, 2500);

            const data = await response.json();

            if (data.success && data.data) {
                completeLastStep();
                addStep('Research completed', 'completed');
                
                // Format output
                let content = '';
                if (typeof data.data === 'string') {
                    content = data.data;
                } else {
                    // Try to format object nicely
                    if (data.data.answer) content += `### Answer\n${data.data.answer}\n\n`;
                    if (data.data.summary) content += `### Summary\n${data.data.summary}\n\n`;
                    if (data.data.results && Array.isArray(data.data.results)) {
                        content += `### Key Findings\n`;
                        data.data.results.forEach((r: any) => {
                            content += `- **${r.score?.toFixed(2) || '?'}**: ${r.content?.substring(0, 150)}...\n`;
                        });
                    }
                    if (!content) content = JSON.stringify(data.data, null, 2);
                }
                
                setStreamedContent(content);
            } else {
                throw new Error(data.error || 'No data returned');
            }

        } catch (error: any) {
            console.error('Research failed:', error);
            failLastStep();
            addStep('Error: ' + error.message, 'failed');
            setStreamedContent(`### Research Failed\n\n${error.message}\n\nPlease ensure the backend is running and the GPU bridge is active.`);
        } finally {
            setIsResearching(false);
        }
    };

    return (
        <div className="h-full flex flex-col bg-card/80 backdrop-blur-sm border border-border/50 rounded-lg overflow-hidden shadow-lg">
            {/* Header */}
            <div className="p-4 border-b border-border/50 bg-gradient-to-r from-purple-500/10 to-blue-500/5 flex items-center justify-between">
                <div className="flex items-center gap-3">
                    <div className="p-2 bg-gradient-to-br from-purple-500 to-blue-600 rounded-lg shadow-md">
                        <Bot className="w-5 h-5 text-white" />
                    </div>
                    <div>
                        <h2 className="font-bold text-foreground tracking-tight">Deep Research Agent</h2>
                        <div className="flex items-center gap-2 text-[10px] font-mono text-muted-foreground">
                            <span className={cn("w-1.5 h-1.5 rounded-full", isResearching ? "bg-green-400 animate-pulse" : "bg-purple-400")} />
                            {isResearching ? "PROCESSING" : "IDLE"} • GPU ENABLED
                        </div>
                    </div>
                </div>
            </div>

            {/* Main Content */}
            <div className="flex-1 flex overflow-hidden">
                {/* Left Panel: Input & Process */}
                <div className="w-[350px] border-r border-border/50 flex flex-col bg-secondary/10">
                    <div className="p-4 border-b border-border/30">
                        <label className="text-xs font-semibold text-muted-foreground uppercase tracking-wider mb-2 block">
                            Research Topic
                        </label>
                        <div className="flex gap-2">
                            <Input
                                value={query}
                                onChange={e => setQuery(e.target.value)}
                                onKeyDown={e => e.key === 'Enter' && startResearch()}
                                placeholder="E.g. Advanced Persistent Threats in 2025..."
                                disabled={isResearching}
                                className="bg-background/50 border-border/50 focus:ring-purple-500/50"
                            />
                            <Button
                                size="icon"
                                onClick={startResearch}
                                disabled={isResearching || !query.trim()}
                                className="bg-purple-600 hover:bg-purple-700 shadow-sm shrink-0"
                            >
                                {isResearching ? <Loader2 className="w-4 h-4 animate-spin" /> : <Sparkles className="w-4 h-4" />}
                            </Button>
                        </div>
                    </div>

                    {/* Agent Thought Process */}
                    <div className="flex-1 overflow-hidden flex flex-col">
                        <div className="p-2 px-4 bg-secondary/20 text-[10px] font-mono text-muted-foreground border-b border-border/30">
                            AGENT PROCESS
                        </div>
                        <ScrollArea className="flex-1 p-4">
                            <div className="space-y-4">
                                {steps.map((step, i) => (
                                    <div key={step.id} className="flex gap-3 animate-in fade-in slide-in-from-left-2 duration-300">
                                        <div className="flex flex-col items-center pt-1">
                                            <div className={cn(
                                                "w-5 h-5 rounded-full flex items-center justify-center text-[10px] border shadow-sm transition-colors duration-500",
                                                step.status === 'completed' ? "bg-green-500/20 border-green-500/50 text-green-500" :
                                                step.status === 'active' ? "bg-purple-500/20 border-purple-500/50 text-purple-500 animate-pulse" :
                                                step.status === 'failed' ? "bg-red-500/20 border-red-500/50 text-red-500" :
                                                "bg-secondary border-muted text-muted-foreground"
                                            )}>
                                                {step.status === 'completed' ? <CheckCircle className="w-3 h-3" /> : 
                                                 step.status === 'failed' ? <AlertCircle className="w-3 h-3" /> :
                                                 i + 1}
                                            </div>
                                            {i < steps.length - 1 && <div className="w-px h-full bg-border/50 my-1" />}
                                        </div>
                                        <div className="pb-2">
                                            <p className={cn(
                                                "text-xs font-medium transition-colors",
                                                step.status === 'active' ? "text-purple-400" : "text-foreground"
                                            )}>{step.description}</p>
                                            {step.details && (
                                                <p className="text-[10px] text-muted-foreground mt-0.5">{step.details}</p>
                                            )}
                                            <span className="text-[9px] text-muted-foreground/50 font-mono mt-1 block">
                                                {step.timestamp.toLocaleTimeString()}
                                            </span>
                                        </div>
                                    </div>
                                ))}
                                {steps.length === 0 && (
                                    <div className="text-center py-8 text-muted-foreground/40 text-xs italic">
                                        Waiting for mission...
                                    </div>
                                )}
                            </div>
                        </ScrollArea>
                    </div>
                </div>

                {/* Right Panel: Results */}
                <div className="flex-1 flex flex-col bg-background/30">
                    <div className="p-2 px-4 bg-secondary/20 text-[10px] font-mono text-muted-foreground border-b border-border/30 flex justify-between items-center">
                        <span>INTELLIGENCE REPORT</span>
                        {streamedContent && (
                            <Badge variant="outline" className="text-[9px] h-4 border-green-500/30 text-green-500 bg-green-500/5">
                                GENERATED
                            </Badge>
                        )}
                    </div>
                    <ScrollArea className="flex-1 p-8">
                        {streamedContent ? (
                            <div className="prose prose-sm dark:prose-invert max-w-none prose-headings:text-purple-400 prose-a:text-blue-400">
                                <ReactMarkdown>{streamedContent}</ReactMarkdown>
                            </div>
                        ) : (
                            <div className="h-full flex flex-col items-center justify-center text-muted-foreground/30">
                                <div className="w-20 h-20 bg-secondary/30 rounded-full flex items-center justify-center mb-4">
                                    <Brain className="w-10 h-10" />
                                </div>
                                <p className="text-sm font-medium">No intelligence generated yet</p>
                                <p className="text-xs mt-1">Enter a topic to begin deep research</p>
                            </div>
                        )}
                    </ScrollArea>
                </div>
            </div>
        </div>
    );
}