"use client";

import { useState, useEffect } from "react";
import Link from "next/link";
import { Card, CardHeader, CardContent } from "./Card";
import Badge from "./Badge";
import Button from "./Button";
import { formatDate } from "@/lib/utils";
import {
	format,
	startOfMonth,
	endOfMonth,
	startOfWeek,
	endOfWeek,
	addDays,
	isSameMonth,
	isSameDay,
	addMonths,
	subMonths,
	parseISO,
	isAfter,
	isBefore,
	startOfDay,
	addWeeks
} from "date-fns";
import { pl } from "date-fns/locale";

const statusColors = {
	registered: "bg-blue-100 text-blue-800",
	approved: "bg-green-100 text-green-800", 
	pending: "bg-yellow-100 text-yellow-800",
	in_progress: "bg-orange-100 text-orange-800",
	fulfilled: "bg-gray-100 text-gray-800",
	cancelled: "bg-red-100 text-red-800",
};

const statusTranslations = {
	registered: "Zarejestrowany",
	approved: "Zatwierdzony",
	pending: "Oczekujący",
	in_progress: "W trakcie",
	fulfilled: "Zakończony",
	cancelled: "Wycofany",
};

export default function ProjectCalendarWidget({ 
	projects = [], 
	compact = false, 
	showUpcoming = true,
	maxUpcoming = 5 
}) {
	const [currentDate, setCurrentDate] = useState(new Date());
	const [viewMode, setViewMode] = useState(compact ? 'upcoming' : 'mini-calendar');

	// Filter projects that have finish dates and are not fulfilled
	const activeProjects = projects.filter(p => 
		p.finish_date && p.project_status !== 'fulfilled'
	);

	const getProjectsForDate = (date) => {
		return activeProjects.filter(project => {
			if (!project.finish_date) return false;
			try {
				const projectDate = parseISO(project.finish_date);
				return isSameDay(projectDate, date);
			} catch (error) {
				return false;
			}
		});
	};

	const getUpcomingProjects = () => {
		const today = startOfDay(new Date());
		const nextMonth = addWeeks(today, 4);
		
		return activeProjects
			.filter(project => {
				if (!project.finish_date) return false;
				try {
					const projectDate = parseISO(project.finish_date);
					return isAfter(projectDate, today) && isBefore(projectDate, nextMonth);
				} catch (error) {
					return false;
				}
			})
			.sort((a, b) => {
				const dateA = parseISO(a.finish_date);
				const dateB = parseISO(b.finish_date);
				return dateA - dateB;
			})
			.slice(0, maxUpcoming);
	};

	const getOverdueProjects = () => {
		const today = startOfDay(new Date());
		
		return activeProjects
			.filter(project => {
				if (!project.finish_date) return false;
				try {
					const projectDate = parseISO(project.finish_date);
					return isBefore(projectDate, today);
				} catch (error) {
					return false;
				}
			})
			.sort((a, b) => {
				const dateA = parseISO(a.finish_date);
				const dateB = parseISO(b.finish_date);
				return dateB - dateA; // Most recently overdue first
			})
			.slice(0, maxUpcoming);
	};

	const renderMiniCalendar = () => {
		const monthStart = startOfMonth(currentDate);
		const monthEnd = endOfMonth(currentDate);
		const calendarStart = startOfWeek(monthStart, { weekStartsOn: 1 });
		const calendarEnd = endOfWeek(monthEnd, { weekStartsOn: 1 });

		const days = [];
		let day = calendarStart;

		while (day <= calendarEnd) {
			days.push(day);
			day = addDays(day, 1);
		}

		const weekdays = ['P', 'W', 'Ś', 'C', 'P', 'S', 'N'];

		return (
			<div className="space-y-3">
				{/* Calendar Header */}
				<div className="flex items-center justify-between">
					<h3 className="text-sm font-medium text-gray-900">
						{format(currentDate, 'LLLL yyyy', { locale: pl })}
					</h3>
					<div className="flex space-x-1">
						<button
							onClick={() => setCurrentDate(subMonths(currentDate, 1))}
							className="p-1 hover:bg-gray-100 rounded"
						>
							<svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
								<path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M15 19l-7-7 7-7" />
							</svg>
						</button>
						<button
							onClick={() => setCurrentDate(addMonths(currentDate, 1))}
							className="p-1 hover:bg-gray-100 rounded"
						>
							<svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
								<path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 5l7 7-7 7" />
							</svg>
						</button>
					</div>
				</div>

				{/* Weekday Headers */}
				<div className="grid grid-cols-7 gap-1">
					{weekdays.map(weekday => (
						<div key={weekday} className="text-xs font-medium text-gray-500 text-center p-1">
							{weekday}
						</div>
					))}
				</div>

				{/* Calendar Grid */}
				<div className="grid grid-cols-7 gap-1">
					{days.map((day, index) => {
						const dayProjects = getProjectsForDate(day);
						const isCurrentMonth = isSameMonth(day, currentDate);
						const isToday = isSameDay(day, new Date());
						const hasProjects = dayProjects.length > 0;
						
						return (
							<div
								key={index}
								className={`text-xs p-1 text-center relative ${
									!isCurrentMonth ? 'text-gray-300' : 
									isToday ? 'bg-blue-100 text-blue-700 font-semibold rounded' : 
									'text-gray-700'
								} ${hasProjects && isCurrentMonth ? 'font-semibold' : ''}`}
								title={hasProjects ? `${dayProjects.length} projekt(ów): ${dayProjects.map(p => p.project_name).join(', ')}` : ''}
							>
								{format(day, 'd')}
								{hasProjects && isCurrentMonth && (
									<div className="absolute bottom-0 left-1/2 transform -translate-x-1/2 w-1 h-1 bg-red-500 rounded-full"></div>
								)}
							</div>
						);
					})}
				</div>
			</div>
		);
	};

	const renderUpcomingList = () => {
		const upcomingProjects = getUpcomingProjects();
		const overdueProjects = getOverdueProjects();

		return (
			<div className="space-y-4">
				{/* Overdue Projects */}
				{overdueProjects.length > 0 && (
					<div>
						<h4 className="text-sm font-medium text-red-600 mb-2">
							Przeterminowane ({overdueProjects.length})
						</h4>
						<div className="space-y-2">
							{overdueProjects.map(project => (
								<Link
									key={project.project_id}
									href={`/projects/${project.project_id}`}
									className="block p-2 bg-red-50 rounded border border-red-200 hover:bg-red-100 transition-colors"
								>
									<div className="text-sm font-medium text-gray-900 truncate">
										{project.project_name}
									</div>
									<div className="text-xs text-red-600">
										{formatDate(project.finish_date)}
									</div>
								</Link>
							))}
						</div>
					</div>
				)}

				{/* Upcoming Projects */}
				{upcomingProjects.length > 0 && (
					<div>
						<h4 className="text-sm font-medium text-gray-900 mb-2">
							Nadchodzące ({upcomingProjects.length})
						</h4>
						<div className="space-y-2">
							{upcomingProjects.map(project => {
								const daysUntilDeadline = Math.ceil((parseISO(project.finish_date) - new Date()) / (1000 * 60 * 60 * 24));
								
								return (
									<Link
										key={project.project_id}
										href={`/projects/${project.project_id}`}
										className="block p-2 bg-gray-50 rounded hover:bg-gray-100 transition-colors"
									>
										<div className="text-sm font-medium text-gray-900 truncate">
											{project.project_name}
										</div>
										<div className="text-xs text-gray-600">
											{formatDate(project.finish_date)} • za {daysUntilDeadline} dni
										</div>
									</Link>
								);
							})}
						</div>
					</div>
				)}

				{upcomingProjects.length === 0 && overdueProjects.length === 0 && (
					<div className="text-sm text-gray-500 text-center py-4">
						Brak nadchodzących terminów
					</div>
				)}
			</div>
		);
	};

	if (activeProjects.length === 0) {
		return (
			<Card>
				<CardHeader>
					<div className="flex items-center justify-between">
						<h3 className="text-lg font-semibold">Kalendarz projektów</h3>
						<Link href="/calendar">
							<Button variant="outline" size="sm">
								Zobacz pełny kalendarz
							</Button>
						</Link>
					</div>
				</CardHeader>
				<CardContent>
					<div className="text-center py-8 text-gray-500 dark:text-gray-400">
						Brak aktywnych projektów z terminami
					</div>
				</CardContent>
			</Card>
		);
	}

	return (
		<Card>
			<CardHeader>
				<div className="flex items-center justify-between">
					<h3 className="text-lg font-semibold">Kalendarz projektów</h3>
					<div className="flex items-center space-x-2">
						{!compact && (
							<div className="flex rounded-md bg-gray-100 p-1">
								<button
									onClick={() => setViewMode('mini-calendar')}
									className={`px-2 py-1 text-xs rounded ${
										viewMode === 'mini-calendar' 
											? 'bg-white text-gray-900 shadow-sm' 
											: 'text-gray-600 hover:text-gray-900'
									}`}
								>
									Kalendarz
								</button>
								<button
									onClick={() => setViewMode('upcoming')}
									className={`px-2 py-1 text-xs rounded ${
										viewMode === 'upcoming' 
											? 'bg-white text-gray-900 shadow-sm' 
											: 'text-gray-600 hover:text-gray-900'
									}`}
								>
									Lista
								</button>
							</div>
						)}
						<Link href="/calendar">
							<Button variant="outline" size="sm">
								Pełny kalendarz
							</Button>
						</Link>
					</div>
				</div>
			</CardHeader>
			<CardContent>
				{viewMode === 'mini-calendar' ? renderMiniCalendar() : renderUpcomingList()}
			</CardContent>
		</Card>
	);
}