import SwiftUI
import Charts

struct ActivityGraphView: View {
    let samples: [IntensitySample]
    let metric: IntensityMetric
    let lowerBound: Double
    let upperBound: Double

    var body: some View {
        Chart {
            ForEach(samples) { sample in
                AreaMark(
                    x: .value("Time", sample.date),
                    y: .value(metric.label, sample.value)
                )
                .foregroundStyle(
                    .linearGradient(
                        colors: [.blue.opacity(0.3), .blue.opacity(0.05)],
                        startPoint: .top,
                        endPoint: .bottom
                    )
                )

                LineMark(
                    x: .value("Time", sample.date),
                    y: .value(metric.label, sample.value)
                )
                .foregroundStyle(.blue)
                .lineStyle(StrokeStyle(lineWidth: 1.5))
            }

            // Dimming overlay for trimmed start region
            if lowerBound > 0, let startDate = samples.first?.date, let endDate = samples.last?.date {
                let trimStart = startDate.addingTimeInterval(
                    lowerBound * endDate.timeIntervalSince(startDate)
                )
                RectangleMark(
                    xStart: .value("", startDate),
                    xEnd: .value("", trimStart)
                )
                .foregroundStyle(Color(.systemBackground).opacity(0.7))
            }

            // Dimming overlay for trimmed end region
            if upperBound < 1, let startDate = samples.first?.date, let endDate = samples.last?.date {
                let trimEnd = startDate.addingTimeInterval(
                    upperBound * endDate.timeIntervalSince(startDate)
                )
                RectangleMark(
                    xStart: .value("", trimEnd),
                    xEnd: .value("", endDate)
                )
                .foregroundStyle(Color(.systemBackground).opacity(0.7))
            }
        }
        .chartXAxis(.hidden)
        .chartYAxis {
            AxisMarks(position: .leading, values: .automatic(desiredCount: 3)) { value in
                AxisGridLine()
                AxisValueLabel {
                    if let v = value.as(Double.self) {
                        Text("\(Int(v))")
                            .font(.caption2)
                    }
                }
            }
        }
        .chartYAxisLabel(metric.label, position: .leading)
    }
}