import SwiftUI
import UIKit

/// The session's events: exams, credits, consultations and coursework defences. They wear an
/// amber of their own — red would read as an error — and each kind its own symbol, so they
/// stand out from ordinary lessons in the schedule, the calendar and the plans.
enum SessionKind {
    case exam, credit, defence, consultation

    init?(_ type: String) {
        switch type {
        case "Экзамен": self = .exam
        case "Зачёт": self = .credit
        case "Защита курсовой работы": self = .defence
        case "Консультация": self = .consultation
        default: return nil
        }
    }

    var label: String {
        switch self {
        case .exam: "Экзамен"
        case .credit: "Зачёт"
        case .defence: "Защита курсовой"
        case .consultation: "Консультация"
        }
    }

    var symbol: String {
        switch self {
        case .exam: "pencil.and.list.clipboard"
        case .credit: "checkmark.seal.fill"
        case .defence: "graduationcap.fill"
        case .consultation: "bubble.left.and.bubble.right.fill"
        }
    }

    /// Exams, credits and defences are filled; consultations are tonal.
    var strong: Bool { self != .consultation }

    var fill: Color { strong ? .sessionStrong : .sessionSoft }
    var content: Color { strong ? .onSessionStrong : .onSessionSoft }
}

extension Lesson {
    var session: SessionKind? { SessionKind(type) }
}

private func dynamic(_ light: UInt32, _ dark: UInt32) -> Color {
    func ui(_ hex: UInt32) -> UIColor {
        UIColor(red: CGFloat((hex >> 16) & 0xFF) / 255, green: CGFloat((hex >> 8) & 0xFF) / 255, blue: CGFloat(hex & 0xFF) / 255, alpha: 1)
    }
    return Color(UIColor { $0.userInterfaceStyle == .dark ? ui(dark) : ui(light) })
}

extension Color {
    /// The session amber (an M3 tonal palette from #8A5100): text, marks and outlines.
    static let sessionAccent = dynamic(0x8A5100, 0xFFB95C)
    static let sessionStrong = dynamic(0x8A5100, 0xFFB95C)
    static let onSessionStrong = dynamic(0xFFFFFF, 0x482900)
    static let sessionSoft = dynamic(0xFFDDB8, 0x693C00)
    static let onSessionSoft = dynamic(0x2C1600, 0xFFDDB8)
}

/// "Зачёт" with its symbol, as a capsule above the subject.
struct SessionBadge: View {
    var kind: SessionKind
    var body: some View {
        Label(kind.label, systemImage: kind.symbol)
            .font(.footnote.weight(.semibold))
            .padding(.horizontal, 10)
            .padding(.vertical, 4)
            .foregroundStyle(kind.content)
            .background(kind.fill, in: .capsule)
    }
}

/// A round marker with the kind's symbol, in place of a subject's dot.
struct SessionDot: View {
    var kind: SessionKind
    var size: CGFloat = 20
    var body: some View {
        Image(systemName: kind.symbol)
            .font(.system(size: size * 0.5, weight: .bold))
            .foregroundStyle(kind.content)
            .frame(width: size, height: size)
            .background(kind.fill, in: .circle)
            .accessibilityHidden(true)
    }
}