/**
 * ApprovalQueueWidget - Human-in-the-Loop Approval Interface
 * 
 * Displays pending requests requiring human approval.
 * Allows users to approve/reject operations in real-time.
 */

import React, { useState, useEffect } from 'react';
import {
    Shield, Check, X, Clock, AlertTriangle, RefreshCw,
    ChevronDown, ChevronUp, Info
} from 'lucide-react';
import { cn } from '@/lib/utils';

interface ApprovalRequest {
    id: string;
    operation: string;
    description: string;
    riskLevel: 'low' | 'medium' | 'high' | 'critical';
    requestedBy: string;
    requestedAt: number;
    expiresAt: number;
    status: 'pending' | 'approved' | 'rejected' | 'expired';
    metadata: Record<string, any>;
}

const API_BASE = 'http://localhost:3001/api';

export default function ApprovalQueueWidget() {
    const [requests, setRequests] = useState<ApprovalRequest[]>([]);
    const [loading, setLoading] = useState(true);
    const [expandedId, setExpandedId] = useState<string | null>(null);
    const [processing, setProcessing] = useState<string | null>(null);

    const fetchPending = async () => {
        try {
            const res = await fetch(`${API_BASE}/approvals/pending`);
            const data = await res.json();
            if (data.success) {
                setRequests(data.requests);
            }
        } catch (error) {
            console.error('Failed to fetch approvals:', error);
        } finally {
            setLoading(false);
        }
    };

    useEffect(() => {
        fetchPending();
        const interval = setInterval(fetchPending, 5000); // Poll every 5s
        return () => clearInterval(interval);
    }, []);

    const handleApprove = async (requestId: string) => {
        setProcessing(requestId);
        try {
            const res = await fetch(`${API_BASE}/approvals/${requestId}/approve`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({ approvedBy: 'Dashboard User' }),
            });

            const data = await res.json();
            if (data.success) {
                await fetchPending(); // Refresh list
            } else {
                alert(`Approval failed: ${data.error}`);
            }
        } catch (error: any) {
            alert(`Error: ${error.message}`);
        } finally {
            setProcessing(null);
        }
    };

    const handleReject = async (requestId: string) => {
        const reason = prompt('Enter rejection reason:');
        if (!reason) return;

        setProcessing(requestId);
        try {
            const res = await fetch(`${API_BASE}/approvals/${requestId}/reject`, {
                method: 'POST',
                headers: { 'Content-Type': 'application/json' },
                body: JSON.stringify({
                    rejectedBy: 'Dashboard User',
                    reason,
                }),
            });

            const data = await res.json();
            if (data.success) {
                await fetchPending();
            } else {
                alert(`Rejection failed: ${data.error}`);
            }
        } catch (error: any) {
            alert(`Error: ${error.message}`);
        } finally {
            setProcessing(null);
        }
    };

    const getRiskColor = (level: string) => {
        switch (level) {
            case 'critical': return 'text-red-400 bg-red-400/10 border-red-400/30';
            case 'high': return 'text-orange-400 bg-orange-400/10 border-orange-400/30';
            case 'medium': return 'text-yellow-400 bg-yellow-400/10 border-yellow-400/30';
            case 'low': return 'text-green-400 bg-green-400/10 border-green-400/30';
            default: return 'text-gray-400 bg-gray-400/10 border-gray-400/30';
        }
    };

    const getRiskIcon = (level: string) => {
        switch (level) {
            case 'critical': return <AlertTriangle className="w-4 h-4 text-red-400" />;
            case 'high': return <AlertTriangle className="w-4 h-4 text-orange-400" />;
            default: return <Shield className="w-4 h-4" />;
        }
    };

    const formatTimeRemaining = (expiresAt: number) => {
        const remaining = expiresAt - Date.now();
        if (remaining < 0) return 'Expired';
        const minutes = Math.floor(remaining / 60000);
        const seconds = Math.floor((remaining % 60000) / 1000);
        return `${minutes}m ${seconds}s`;
    };

    return (
        <div className="h-full flex flex-col bg-card/50 backdrop-blur-sm border border-border/50 rounded-lg overflow-hidden">
            {/* Header */}
            <div className="flex items-center justify-between p-4 border-b border-border/30 bg-gradient-to-r from-orange-500/10 to-transparent">
                <div className="flex items-center gap-2">
                    <Shield className="w-5 h-5 text-orange-400" />
                    <span className="font-display text-sm uppercase tracking-wider text-orange-400">
                        Approval Queue
                    </span>
                </div>
                <div className="flex items-center gap-2">
                    {requests.length > 0 && (
                        <span className="px-2 py-1 bg-orange-400/20 text-orange-400 rounded text-xs font-medium">
                            {requests.length} pending
                        </span>
                    )}
                    <button
                        onClick={fetchPending}
                        className="p-1.5 hover:bg-secondary/50 rounded transition-colors"
                        disabled={loading}
                    >
                        <RefreshCw className={cn("w-4 h-4 text-orange-400", loading && "animate-spin")} />
                    </button>
                </div>
            </div>

            {/* Content */}
            <div className="flex-1 overflow-y-auto p-4 space-y-3">
                {loading ? (
                    <div className="flex items-center justify-center h-32">
                        <RefreshCw className="w-6 h-6 text-orange-400 animate-spin" />
                    </div>
                ) : requests.length === 0 ? (
                    <div className="text-center py-8">
                        <Check className="w-8 h-8 text-green-400 mx-auto mb-2" />
                        <p className="text-sm text-muted-foreground">No pending approvals</p>
                    </div>
                ) : (
                    requests.map(request => {
                        const isExpanded = expandedId === request.id;
                        const timeRemaining = formatTimeRemaining(request.expiresAt);
                        const isExpiringSoon = request.expiresAt - Date.now() < 60000; // < 1 min

                        return (
                            <div
                                key={request.id}
                                className={cn(
                                    "border rounded-lg overflow-hidden transition-all",
                                    getRiskColor(request.riskLevel)
                                )}
                            >
                                {/* Header */}
                                <div className="p-3">
                                    <div className="flex items-start justify-between gap-3">
                                        <div className="flex-1">
                                            <div className="flex items-center gap-2 mb-1">
                                                {getRiskIcon(request.riskLevel)}
                                                <span className="text-xs font-medium uppercase tracking-wide opacity-70">
                                                    {request.riskLevel} risk
                                                </span>
                                                <span className="text-xs opacity-50">•</span>
                                                <span className="text-xs font-mono opacity-70">{request.operation}</span>
                                            </div>
                                            <p className="text-sm mb-2">{request.description}</p>
                                            <div className="flex items-center gap-3 text-xs opacity-60">
                                                <div className="flex items-center gap-1">
                                                    <Clock className="w-3 h-3" />
                                                    <span className={cn(isExpiringSoon && "text-red-400 font-medium")}>
                                                        {timeRemaining}
                                                    </span>
                                                </div>
                                                <span>•</span>
                                                <span>{request.requestedBy}</span>
                                            </div>
                                        </div>
                                        <button
                                            onClick={() => setExpandedId(isExpanded ? null : request.id)}
                                            className="p-1 hover:bg-black/20 rounded transition-colors"
                                        >
                                            {isExpanded ? (
                                                <ChevronUp className="w-4 h-4" />
                                            ) : (
                                                <ChevronDown className="w-4 h-4" />
                                            )}
                                        </button>
                                    </div>

                                    {/* Expanded details */}
                                    {isExpanded && (
                                        <div className="mt-3 pt-3 border-t border-current/20">
                                            <div className="space-y-2 text-xs">
                                                {Object.entries(request.metadata).map(([key, value]) => (
                                                    <div key={key} className="flex items-start gap-2">
                                                        <Info className="w-3 h-3 mt-0.5 opacity-50" />
                                                        <span className="font-medium opacity-70">{key}:</span>
                                                        <span className="opacity-90">{String(value)}</span>
                                                    </div>
                                                ))}
                                            </div>
                                        </div>
                                    )}

                                    {/* Action buttons */}
                                    <div className="flex gap-2 mt-3">
                                        <button
                                            onClick={() => handleApprove(request.id)}
                                            disabled={processing === request.id}
                                            className={cn(
                                                "flex-1 flex items-center justify-center gap-2 px-3 py-2 rounded text-xs font-medium transition-all",
                                                "bg-green-500/20 text-green-400 hover:bg-green-500/30",
                                                processing === request.id && "opacity-50 cursor-not-allowed"
                                            )}
                                        >
                                            <Check className="w-3 h-3" />
                                            Approve
                                        </button>
                                        <button
                                            onClick={() => handleReject(request.id)}
                                            disabled={processing === request.id}
                                            className={cn(
                                                "flex-1 flex items-center justify-center gap-2 px-3 py-2 rounded text-xs font-medium transition-all",
                                                "bg-red-500/20 text-red-400 hover:bg-red-500/30",
                                                processing === request.id && "opacity-50 cursor-not-allowed"
                                            )}
                                        >
                                            <X className="w-3 h-3" />
                                            Reject
                                        </button>
                                    </div>
                                </div>
                            </div>
                        );
                    })
                )}
            </div>

            {/* Footer */}
            <div className="p-3 border-t border-border/30 bg-secondary/20">
                <p className="text-xs text-muted-foreground text-center">
                    🔐 Human-in-the-Loop: Ingen handlinger udført uden din godkendelse
                </p>
            </div>
        </div>
    );
}