import SwiftUI

/// A physical key. `latched` keeps it looking pressed (REC while recording).
public struct KeyButtonStyle: ButtonStyle {
    public enum Kind { case standard, record }

    private let kind: Kind
    private let latched: Bool

    public init(kind: Kind = .standard, latched: Bool = false) {
        self.kind = kind
        self.latched = latched
    }

    public func makeBody(configuration: Configuration) -> some View {
        KeyBody(configuration: configuration, kind: kind, latched: latched)
    }

    private struct KeyBody: View {
        let configuration: Configuration
        let kind: Kind
        let latched: Bool
        @Environment(\.isEnabled) private var isEnabled
        @Environment(\.accessibilityReduceMotion) private var reduceMotion

        private var pressed: Bool { configuration.isPressed || latched }

        private var face: AnyShapeStyle {
            switch (kind, pressed) {
            case (.standard, false):
                AnyShapeStyle(LinearGradient(colors: [Palette.surfaceKeyHigh, Palette.surfaceKeyLow], startPoint: .top, endPoint: .bottom))
            case (.standard, true):
                AnyShapeStyle(Palette.surfaceKeyPressed)
            case (.record, false):
                AnyShapeStyle(Palette.accentRecord)
            case (.record, true):
                AnyShapeStyle(Palette.accentRecord.opacity(Opacity.pressedRecord))
            }
        }

        var body: some View {
            configuration.label
                .textStyle(Typography.control)
                .foregroundStyle(kind == .record ? Palette.inkInverse : Palette.inkPrimary)
                .padding(.horizontal, Space.s4)
                .frame(
                    minWidth: kind == .record ? Size.keyRecWidth : Size.keyMinWidth,
                    minHeight: kind == .record ? Size.keyRecHeight : Size.controlHeight)
                .background(PhysicalSurface(
                    fill: face, cornerRadius: Radius.sm,
                    shadows: pressed ? Shadows.keyPressed : Shadows.keyRaised))
                .offset(y: pressed ? Shadows.keyPressedOffset : 0)
                .opacity(isEnabled ? 1 : Opacity.disabled)
                .animation(
                    reduceMotion ? nil : .timingCurve(
                        Motion.easingMechanical.0, Motion.easingMechanical.1, Motion.easingMechanical.2, Motion.easingMechanical.3,
                        duration: pressed ? Motion.keyPress : Motion.keyRelease),
                    value: pressed)
        }
    }
}

/// A round indicator lamp. The record lamp has a small glow; text never does.
public struct LampView: View {
    public enum Tint { case record, amber }

    private let isOn: Bool
    private let tint: Tint
    private let large: Bool
    @Environment(\.colorScheme) private var scheme
    @Environment(\.accessibilityReduceMotion) private var reduceMotion

    public init(isOn: Bool, tint: Tint = .record, large: Bool = false) {
        self.isOn = isOn
        self.tint = tint
        self.large = large
    }

    private var color: Color {
        switch (tint, isOn) {
        case (.record, true): Palette.accentRecord
        case (.record, false): Palette.accentRecordUnlit
        case (.amber, true): Palette.levelAmber
        case (.amber, false): Palette.levelAmberUnlit
        }
    }

    public var body: some View {
        let diameter = large ? Size.lampLarge : Size.lampDiameter
        let glow = Shadows.lampOn[0]
        Circle()
            .fill(color)
            .overlay(
                Circle().fill(RadialGradient(
                    colors: [Color.white.opacity(isOn ? Opacity.specularOn : Opacity.specularOff), .clear],
                    center: UnitPoint(x: 0.35, y: 0.3), startRadius: 0, endRadius: diameter * 0.45)))
            .overlay(Circle().strokeBorder(Palette.lineSeamDark, lineWidth: Border.hairline))
            .frame(width: diameter, height: diameter)
            .shadow(
                color: isOn && tint == .record ? glow.color(scheme) : .clear,
                radius: glow.blur / 2)
            .animation(
                reduceMotion ? nil : .easeOut(duration: isOn ? Motion.lampOn : Motion.lampOff),
                value: isOn)
            .accessibilityHidden(true)
    }
}