import SwiftUI

struct ActiveWorkoutView: View {
    @ObservedObject var workoutManager: WorkoutManager

    var body: some View {
        TabView {
            if workoutManager.isResting {
                RestPage(workoutManager: workoutManager)
            } else {
                ActivePage(workoutManager: workoutManager)
            }
            WorkoutOverviewPage(workoutManager: workoutManager)
            ControlsPage(workoutManager: workoutManager)
        }
        .tabViewStyle(.verticalPage)
    }
}

// MARK: - Page 1: Active / Rest

struct ActivePage: View {
    @ObservedObject var workoutManager: WorkoutManager

    var body: some View {
        VStack(spacing: 6) {
            if let workout = workoutManager.selectedWorkout,
               workoutManager.currentSetIndex < workout.sets.count {
                let currentSet = workout.sets[workoutManager.currentSetIndex]

                HStack {
                    Text("Set \(workoutManager.currentSetIndex + 1)/\(workout.sets.count)")
                        .font(.caption2)
                        .foregroundColor(.secondary)
                    Text("·")
                        .foregroundColor(.secondary)
                    Text("Rep \(workoutManager.currentRep + 1)/\(currentSet.repCount)")
                        .font(.caption2)
                        .foregroundColor(.secondary)
                }

                Text(currentSet.stroke)
                    .font(.headline)
                    .foregroundColor(.cyan)

                Text("\(Int(workoutManager.currentSetDistanceSwum))/\(Int(workoutManager.currentSetTotalDistance))m")
                    .font(.system(size: 36, weight: .bold, design: .rounded))
                    .foregroundColor(.cyan)
            }

            HStack(spacing: 4) {
                Image(systemName: "figure.pool.swim")
                    .font(.caption)
                    .foregroundColor(.cyan)
                Text("\(Int(workoutManager.totalDistanceSwum))m total")
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            Text(formatTime(workoutManager.elapsedSeconds))
                .font(.system(.title3, design: .monospaced))

            HStack(spacing: 12) {
                HStack(spacing: 4) {
                    Image(systemName: "flame.fill")
                        .foregroundColor(.orange)
                        .font(.caption)
                    Text("\(Int(workoutManager.activeCalories))")
                        .font(.caption)
                }

                if workoutManager.heartRate > 0 {
                    HStack(spacing: 4) {
                        Image(systemName: "heart.fill")
                            .foregroundColor(.red)
                            .font(.caption)
                        Text("\(Int(workoutManager.heartRate))")
                            .font(.caption)
                    }
                }
            }

            if workoutManager.lapDetected {
                Text("Lap detected!")
                    .font(.caption)
                    .foregroundColor(.green)
                    .transition(.opacity)
            }
        }
    }

    private func formatTime(_ seconds: TimeInterval) -> String {
        let mins = Int(seconds) / 60
        let secs = Int(seconds) % 60
        return String(format: "%d:%02d", mins, secs)
    }
}

struct RestPage: View {
    @ObservedObject var workoutManager: WorkoutManager

    var body: some View {
        VStack(spacing: 12) {
            Text("Rest")
                .font(.headline)
                .foregroundColor(.secondary)

            Text(formatTime(workoutManager.restTimeRemaining))
                .font(.system(size: 44, weight: .bold, design: .monospaced))
                .foregroundColor(.cyan)

            if let workout = workoutManager.selectedWorkout,
               workoutManager.currentSetIndex + 1 < workout.sets.count {
                let nextSet = workout.sets[workoutManager.currentSetIndex + 1]
                Text("Next: \(nextSet.stroke) \(nextSet.distancePerRep)m")
                    .font(.caption)
                    .foregroundColor(.secondary)
            }

            HStack(spacing: 12) {
                HStack(spacing: 4) {
                    Image(systemName: "figure.pool.swim")
                        .font(.caption)
                        .foregroundColor(.cyan)
                    Text("\(Int(workoutManager.totalDistanceSwum))m")
                        .font(.caption)
                }
                HStack(spacing: 4) {
                    Image(systemName: "flame.fill")
                        .foregroundColor(.orange)
                        .font(.caption)
                    Text("\(Int(workoutManager.activeCalories))kcal")
                        .font(.caption)
                }
            }
            .foregroundColor(.secondary)
        }
    }

    private func formatTime(_ seconds: TimeInterval) -> String {
        let mins = Int(seconds) / 60
        let secs = Int(seconds) % 60
        return String(format: "%d:%02d", mins, secs)
    }
}

// MARK: - Page 2: Workout Overview

struct WorkoutOverviewPage: View {
    @ObservedObject var workoutManager: WorkoutManager

    var body: some View {
        ScrollView {
            VStack(alignment: .leading, spacing: 6) {
                if workoutManager.isResting {
                    HStack {
                        Image(systemName: "pause.circle.fill")
                            .foregroundColor(.orange)
                            .font(.caption)
                        Text("Rest \(formatTime(workoutManager.restTimeRemaining))")
                            .font(.caption)
                            .foregroundColor(.orange)
                    }
                }

                if let workout = workoutManager.selectedWorkout {
                    ForEach(Array(workout.sets.enumerated()), id: \.offset) { i, set in
                        HStack {
                            Circle()
                                .fill(i < workoutManager.currentSetIndex ? .green :
                                        i == workoutManager.currentSetIndex ? .cyan : .gray.opacity(0.4))
                                .frame(width: 8, height: 8)
                            Text("\(i + 1). \(set.stroke)")
                                .font(.caption)
                                .foregroundColor(i <= workoutManager.currentSetIndex ? .primary : .secondary)
                            Spacer()
                            Text("\(set.repCount)x\(set.distancePerRep)m")
                                .font(.caption2)
                                .foregroundColor(.secondary)
                        }
                    }
                }
            }
            .padding(.top, 4)
        }
    }

    private func formatTime(_ seconds: TimeInterval) -> String {
        let mins = Int(seconds) / 60
        let secs = Int(seconds) % 60
        return String(format: "%d:%02d", mins, secs)
    }
}

// MARK: - Page 3: Controls

struct ControlsPage: View {
    @ObservedObject var workoutManager: WorkoutManager

    var body: some View {
        VStack(spacing: 16) {
            if workoutManager.isWaterLockEnabled {
                HStack(spacing: 4) {
                    Image(systemName: "drop.fill")
                        .foregroundColor(.cyan)
                        .font(.caption)
                    Text("Water Lock")
                        .font(.caption)
                        .foregroundColor(.cyan)
                }
            }

            Spacer()

            Button {
                if workoutManager.isPaused {
                    workoutManager.resumeWorkout()
                } else {
                    workoutManager.pauseWorkout()
                }
            } label: {
                VStack(spacing: 4) {
                    Image(systemName: workoutManager.isPaused ? "play.fill" : "pause.fill")
                        .font(.title2)
                    Text(workoutManager.isPaused ? "Resume" : "Pause")
                        .font(.caption)
                }
                .frame(maxWidth: .infinity)
            }
            .buttonStyle(.borderedProminent)
            .tint(.orange)

            Button {
                workoutManager.endWorkout()
            } label: {
                VStack(spacing: 4) {
                    Image(systemName: "stop.fill")
                        .font(.title2)
                    Text("End Workout")
                        .font(.caption)
                }
                .frame(maxWidth: .infinity)
            }
            .buttonStyle(.borderedProminent)
            .tint(.red)

            Spacer()
        }
    }
}