import SwiftUI

/// Seven-segment counter on dark glass. Digits, ":" and "." are drawn; unlit segments stay faintly visible.
public struct SegmentCounterView: View {
    private let text: String

    public init(_ text: String) {
        self.text = text
    }

    private var contentWidth: CGFloat {
        text.reduce(0) { total, character in
            total + (character.isNumber ? Segment.advance : Segment.colonWidth)
        }
    }

    public var body: some View {
        Canvas { context, _ in
            var x: CGFloat = 0
            for character in text {
                if character.isNumber {
                    var origin = context
                    origin.translateBy(x: x, y: 0)
                    let lit = SegmentGlyph.lit(for: character)
                    for id in SegmentID.allCases {
                        let polygon = SegmentGlyph.polygon(id)
                        var path = Path()
                        path.addLines(polygon)
                        path.closeSubpath()
                        origin.fill(path, with: .color(lit.contains(id) ? Palette.levelAmber : Palette.displaySegmentUnlit))
                    }
                    x += Segment.advance
                } else {
                    let dot = Segment.thickness
                    let inset = (Segment.colonWidth - dot) / 2
                    let ys: [CGFloat] = character == ":"
                        ? [Segment.digitHeight * 0.28, Segment.digitHeight * 0.64]
                        : [Segment.digitHeight - dot]
                    for y in ys {
                        context.fill(Path(CGRect(x: x + inset, y: y, width: dot, height: dot)), with: .color(Palette.levelAmber))
                    }
                    x += Segment.colonWidth
                }
            }
        }
        .frame(width: contentWidth, height: Segment.digitHeight)
        .padding(.horizontal, Space.s4)
        .padding(.vertical, Space.s3)
        .background(DisplayBackground())
        .accessibilityElement()
        .accessibilityLabel("Tijd")
        .accessibilityValue(text)
    }
}

/// Twelve-segment level bar: green, amber, then one red segment.
public struct LEDBarView: View {
    private let fraction: Double

    public init(fraction: Double) {
        self.fraction = fraction
    }

    public var body: some View {
        let lit = LEDBar.litCount(forFraction: fraction)
        HStack(spacing: MeterTokens.ledGap) {
            ForEach(0..<MeterTokens.ledSegments, id: \.self) { index in
                RoundedRectangle(cornerRadius: Radius.sharp, style: .circular)
                    .fill(color(for: index, lit: index < lit))
                    .frame(width: MeterTokens.ledSegmentWidth, height: MeterTokens.ledSegmentHeight)
            }
        }
        .accessibilityHidden(true)
    }

    private func color(for index: Int, lit: Bool) -> Color {
        switch LEDBar.tone(forSegment: index) {
        case .green: lit ? Palette.levelGreen : Palette.levelGreenUnlit
        case .amber: lit ? Palette.levelAmber : Palette.levelAmberUnlit
        case .red: lit ? Palette.accentRecord : Palette.accentRecordUnlit
        }
    }
}