"use client";

import { useState, useEffect } from "react";
import { Download, Loader2, Music, Disc, X, Trash2 } from "lucide-react";
import { api } from "@/lib/api";
import { cn } from "@/utils/cn";
import { GradientSpinner } from "../ui/GradientSpinner";

interface ActiveDownload {
    id: string;
    subject: string;
    type: string;
    status: string;
    createdAt: string;
}

export function ActiveDownloadsTab() {
    const [downloads, setDownloads] = useState<ActiveDownload[]>([]);
    const [loading, setLoading] = useState(true);
    const [cancelling, setCancelling] = useState<Set<string>>(new Set());

    const fetchDownloads = async () => {
        try {
            const data = await api.getActiveDownloads();
            setDownloads(data);
        } catch (error) {
            console.error("Failed to fetch active downloads:", error);
        } finally {
            setLoading(false);
        }
    };

    const handleCancel = async (id: string) => {
        setCancelling(prev => new Set(prev).add(id));
        try {
            await api.deleteDownload(id);
            // Optimistically remove from list
            setDownloads(prev => prev.filter(d => d.id !== id));
        } catch (error) {
            console.error("Failed to cancel download:", error);
        } finally {
            setCancelling(prev => {
                const next = new Set(prev);
                next.delete(id);
                return next;
            });
        }
    };

    const handleCancelAll = async () => {
        const ids = downloads.map(d => d.id);
        setCancelling(new Set(ids));
        try {
            // Cancel all downloads in parallel
            await Promise.all(ids.map(id => api.deleteDownload(id)));
            setDownloads([]);
        } catch (error) {
            console.error("Failed to cancel all downloads:", error);
            // Refresh to get actual state
            fetchDownloads();
        } finally {
            setCancelling(new Set());
        }
    };

    useEffect(() => {
        fetchDownloads();

        // Poll for updates every 5 seconds
        const interval = setInterval(fetchDownloads, 5000);
        return () => clearInterval(interval);
    }, []);

    const formatTime = (dateStr: string) => {
        const date = new Date(dateStr);
        const now = new Date();
        const diff = now.getTime() - date.getTime();
        
        if (diff < 60000) return "Just started";
        if (diff < 3600000) return `${Math.floor(diff / 60000)}m`;
        if (diff < 86400000) return `${Math.floor(diff / 3600000)}h`;
        return date.toLocaleDateString();
    };

    if (loading) {
        return (
            <div className="flex items-center justify-center py-8">
                <div className="w-5 h-5 border-2 border-white/20 border-t-white/60 rounded-full animate-spin" />
            </div>
        );
    }

    if (downloads.length === 0) {
        return (
            <div className="flex flex-col items-center justify-center py-12 text-center">
                <Download className="w-8 h-8 text-white/20 mb-3" />
                <p className="text-sm text-white/40">No active downloads</p>
                <p className="text-xs text-white/30 mt-1">Downloads will appear here</p>
            </div>
        );
    }

    return (
        <div className="flex flex-col h-full">
            {/* Header */}
            <div className="flex items-center justify-between px-3 py-2 border-b border-white/5">
                <span className="text-xs text-white/40">
                    {downloads.length} downloading
                </span>
                <div className="flex items-center gap-3">
                    <button
                        onClick={handleCancelAll}
                        className="text-xs text-white/40 hover:text-red-400 transition-colors"
                        title="Cancel all downloads"
                    >
                        Cancel all
                    </button>
                    <span className="flex items-center gap-1.5 text-xs text-green-400">
                        <span className="w-1.5 h-1.5 rounded-full bg-green-400 animate-pulse" />
                        Active
                    </span>
                </div>
            </div>

            {/* Download list */}
            <div className="flex-1 overflow-y-auto">
                {downloads.map((download) => (
                    <div
                        key={download.id}
                        className="px-3 py-3 border-b border-white/5 hover:bg-white/5 transition-colors group"
                    >
                        <div className="flex items-start gap-3">
                            <div className="mt-0.5 shrink-0">
                                {cancelling.has(download.id) ? (
                                    <Loader2 className="w-4 h-4 text-white/40 animate-spin" />
                                ) : (
                                    <GradientSpinner size="sm" />
                                )}
                            </div>
                            <div className="flex-1 min-w-0">
                                <p className="text-sm font-medium text-white truncate">
                                    {download.subject}
                                </p>
                                <div className="flex items-center gap-2 mt-1">
                                    <span className={cn(
                                        "text-xs font-medium capitalize",
                                        download.status === "processing" ? "text-blue-400" : "text-yellow-400"
                                    )}>
                                        {download.status}
                                    </span>
                                    <span className="text-xs text-white/30">•</span>
                                    <span className="text-xs text-white/30 capitalize flex items-center gap-1">
                                        {download.type === "album" ? (
                                            <Disc className="w-3 h-3" />
                                        ) : (
                                            <Music className="w-3 h-3" />
                                        )}
                                        {download.type}
                                    </span>
                                    <span className="text-xs text-white/30">•</span>
                                    <span className="text-xs text-white/30">
                                        {formatTime(download.createdAt)}
                                    </span>
                                </div>
                            </div>
                            <button
                                onClick={() => handleCancel(download.id)}
                                disabled={cancelling.has(download.id)}
                                className="p-1 opacity-0 group-hover:opacity-100 hover:bg-white/10 rounded transition-all shrink-0"
                                title="Cancel download"
                            >
                                <X className="w-4 h-4 text-white/40 hover:text-red-400" />
                            </button>
                        </div>
                    </div>
                ))}
            </div>
        </div>
    );
}
