import Foundation

class SolsticeData {
    static let shared = SolsticeData()

    private let events: [SolsticeEvent]

    private init() {
        var allEvents: [SolsticeEvent] = []

        // 2025
        allEvents.append(SolsticeEvent(name: "Vårjevndøgn 2025", date: SolsticeData.dateFromUTC(year: 2025, month: 3, day: 20, hour: 9, minute: 1), season: .spring))
        allEvents.append(SolsticeEvent(name: "Sommersolverv 2025", date: SolsticeData.dateFromUTC(year: 2025, month: 6, day: 20, hour: 14, minute: 42), season: .summer))
        allEvents.append(SolsticeEvent(name: "Høstjevndøgn 2025", date: SolsticeData.dateFromUTC(year: 2025, month: 9, day: 22, hour: 18, minute: 20), season: .autumn))
        allEvents.append(SolsticeEvent(name: "Vintersolverv 2025", date: SolsticeData.dateFromUTC(year: 2025, month: 12, day: 21, hour: 15, minute: 3), season: .winter))

        // 2026
        allEvents.append(SolsticeEvent(name: "Vårjevndøgn 2026", date: SolsticeData.dateFromUTC(year: 2026, month: 3, day: 20, hour: 14, minute: 46), season: .spring))
        allEvents.append(SolsticeEvent(name: "Sommersolverv 2026", date: SolsticeData.dateFromUTC(year: 2026, month: 6, day: 21, hour: 8, minute: 25), season: .summer))
        allEvents.append(SolsticeEvent(name: "Høstjevndøgn 2026", date: SolsticeData.dateFromUTC(year: 2026, month: 9, day: 23, hour: 0, minute: 6), season: .autumn))
        allEvents.append(SolsticeEvent(name: "Vintersolverv 2026", date: SolsticeData.dateFromUTC(year: 2026, month: 12, day: 21, hour: 20, minute: 50), season: .winter))

        // 2027
        allEvents.append(SolsticeEvent(name: "Vårjevndøgn 2027", date: SolsticeData.dateFromUTC(year: 2027, month: 3, day: 20, hour: 20, minute: 25), season: .spring))
        allEvents.append(SolsticeEvent(name: "Sommersolverv 2027", date: SolsticeData.dateFromUTC(year: 2027, month: 6, day: 21, hour: 14, minute: 11), season: .summer))
        allEvents.append(SolsticeEvent(name: "Høstjevndøgn 2027", date: SolsticeData.dateFromUTC(year: 2027, month: 9, day: 23, hour: 6, minute: 2), season: .autumn))
        allEvents.append(SolsticeEvent(name: "Vintersolverv 2027", date: SolsticeData.dateFromUTC(year: 2027, month: 12, day: 22, hour: 2, minute: 43), season: .winter))

        // 2028
        allEvents.append(SolsticeEvent(name: "Vårjevndøgn 2028", date: SolsticeData.dateFromUTC(year: 2028, month: 3, day: 20, hour: 2, minute: 17), season: .spring))
        allEvents.append(SolsticeEvent(name: "Sommersolverv 2028", date: SolsticeData.dateFromUTC(year: 2028, month: 6, day: 20, hour: 20, minute: 2), season: .summer))
        allEvents.append(SolsticeEvent(name: "Høstjevndøgn 2028", date: SolsticeData.dateFromUTC(year: 2028, month: 9, day: 22, hour: 11, minute: 45), season: .autumn))
        allEvents.append(SolsticeEvent(name: "Vintersolverv 2028", date: SolsticeData.dateFromUTC(year: 2028, month: 12, day: 21, hour: 8, minute: 20), season: .winter))

        // 2029
        allEvents.append(SolsticeEvent(name: "Vårjevndøgn 2029", date: SolsticeData.dateFromUTC(year: 2029, month: 3, day: 20, hour: 8, minute: 1), season: .spring))
        allEvents.append(SolsticeEvent(name: "Sommersolverv 2029", date: SolsticeData.dateFromUTC(year: 2029, month: 6, day: 21, hour: 1, minute: 48), season: .summer))
        allEvents.append(SolsticeEvent(name: "Høstjevndøgn 2029", date: SolsticeData.dateFromUTC(year: 2029, month: 9, day: 22, hour: 17, minute: 37), season: .autumn))
        allEvents.append(SolsticeEvent(name: "Vintersolverv 2029", date: SolsticeData.dateFromUTC(year: 2029, month: 12, day: 21, hour: 14, minute: 14), season: .winter))

        // 2030
        allEvents.append(SolsticeEvent(name: "Vårjevndøgn 2030", date: SolsticeData.dateFromUTC(year: 2030, month: 3, day: 20, hour: 13, minute: 51), season: .spring))
        allEvents.append(SolsticeEvent(name: "Sommersolverv 2030", date: SolsticeData.dateFromUTC(year: 2030, month: 6, day: 21, hour: 7, minute: 31), season: .summer))
        allEvents.append(SolsticeEvent(name: "Høstjevndøgn 2030", date: SolsticeData.dateFromUTC(year: 2030, month: 9, day: 22, hour: 23, minute: 27), season: .autumn))
        allEvents.append(SolsticeEvent(name: "Vintersolverv 2030", date: SolsticeData.dateFromUTC(year: 2030, month: 12, day: 21, hour: 20, minute: 9), season: .winter))

        self.events = allEvents.sorted { $0.date < $1.date }
    }

    private static func dateFromUTC(year: Int, month: Int, day: Int, hour: Int, minute: Int) -> Date {
        var components = DateComponents()
        components.year = year
        components.month = month
        components.day = day
        components.hour = hour
        components.minute = minute
        components.second = 0
        components.timeZone = TimeZone(abbreviation: "UTC")
        return Calendar(identifier: .gregorian).date(from: components) ?? Date()
    }

    func nextEvent(from now: Date = Date()) -> SolsticeEvent? {
        return events.first { $0.date > now }
    }

    func upcomingEvents(count: Int, from now: Date = Date()) -> [SolsticeEvent] {
        let futureEvents = events.filter { $0.date > now }
        return Array(futureEvents.prefix(count))
    }

    func progressToNextEvent(from now: Date = Date()) -> (elapsed: Int, total: Int)? {
        guard let _ = nextEvent(from: now) else { return nil }

        let today = Calendar.current.startOfDay(for: now)

        guard let previousEventIndex = events.firstIndex(where: { $0.date > now }) else {
            return nil
        }

        guard previousEventIndex > 0 else { return nil }

        let nextEvent = events[previousEventIndex]
        let previousEvent = events[previousEventIndex - 1]

        let previousEventDay = Calendar.current.startOfDay(for: previousEvent.date)
        let eventDay = Calendar.current.startOfDay(for: nextEvent.date)

        let elapsedComponents = Calendar.current.dateComponents([.day], from: previousEventDay, to: today)
        let totalComponents = Calendar.current.dateComponents([.day], from: previousEventDay, to: eventDay)

        let elapsed = max(0, elapsedComponents.day ?? 0)
        let total = max(1, totalComponents.day ?? 1)

        return (elapsed: elapsed, total: total)
    }
}