//
// WorkoutLiveActivity.swift
// Workouts Widget
//
// Copyright 2025 Rouslan Zenetl. All Rights Reserved.
//

import ActivityKit
import SwiftUI
import WidgetKit

/// The active-workout Live Activity: a lock-screen / banner presentation plus the Dynamic
/// Island (compact, minimal, expanded). Every timer renders straight off the content state's
/// wall-clock anchors via `Text(timerInterval:)` / `ProgressView(timerInterval:)`, so the
/// countdowns stay live while the phone is locked with **no push updates**.
///
/// Backgrounds are left to the system (lock-screen material / Dynamic Island black), so light
/// and dark both look right without hardcoding a fill. Phase tints echo the in-app run flow —
/// brand purple for work, teal for rest.
struct WorkoutLiveActivity: Widget {
    var body: some WidgetConfiguration {
        ActivityConfiguration(for: WorkoutActivityAttributes.self) { context in
            LockScreenView(state: context.state)
                .activitySystemActionForegroundColor(.primary)
        } dynamicIsland: { context in
            let state = context.state
            return DynamicIsland {
                DynamicIslandExpandedRegion(.leading) {
                    Label(state.phaseTitle, systemImage: Glyph.exercise)
                        .font(.caption.weight(.semibold))
                        .foregroundStyle(state.phase.tint)
                        .padding(.leading, 4)
                }
                DynamicIslandExpandedRegion(.trailing) {
                    TimerLabel(state: state)
                        .font(.system(.title3, design: .rounded, weight: .semibold))
                        .foregroundStyle(state.phase.tint)
                        .frame(maxWidth: 96, alignment: .trailing)
                        .padding(.trailing, 4)
                }
                DynamicIslandExpandedRegion(.bottom) {
                    VStack(alignment: .leading, spacing: 4) {
                        Text(state.exerciseName)
                            .font(.headline)
                            .lineLimit(1)
                        Text(state.statusLine)
                            .font(.subheadline)
                            .foregroundStyle(.secondary)
                            .lineLimit(1)
                        if let end = state.phaseEnd {
                            ProgressView(timerInterval: state.phaseStart...end, countsDown: true) {
                                EmptyView()
                            } currentValueLabel: {
                                EmptyView()
                            }
                            .tint(state.phase.tint)
                        }
                    }
                    .padding(.top, 2)
                }
            } compactLeading: {
                Image(systemName: Glyph.exercise)
                    .foregroundStyle(state.phase.tint)
            } compactTrailing: {
                if let end = state.phaseEnd {
                    CountdownText(start: state.phaseStart, end: end)
                        .foregroundStyle(state.phase.tint)
                        .frame(maxWidth: 52)
                } else {
                    Text("\(state.setNumber)/\(state.setCount)")
                        .monospacedDigit()
                }
            } minimal: {
                if let end = state.phaseEnd {
                    CountdownText(start: state.phaseStart, end: end)
                        .foregroundStyle(state.phase.tint)
                        .frame(maxWidth: 52)
                } else {
                    Image(systemName: Glyph.exercise)
                        .foregroundStyle(state.phase.tint)
                }
            }
            .keylineTint(state.phase.tint)
        }
    }
}

// MARK: - Lock screen / banner

private struct LockScreenView: View {
    let state: WorkoutActivityAttributes.ContentState

    var body: some View {
        HStack(alignment: .center, spacing: 14) {
            Image(systemName: Glyph.exercise)
                .font(.title2)
                .foregroundStyle(state.phase.tint)
                .frame(width: 30)

            VStack(alignment: .leading, spacing: 4) {
                Text(state.exerciseName)
                    .font(.headline)
                    .lineLimit(1)
                Text(state.statusLine)
                    .font(.subheadline)
                    .foregroundStyle(.secondary)
                    .lineLimit(1)
                if let end = state.phaseEnd {
                    ProgressView(timerInterval: state.phaseStart...end, countsDown: true) {
                        EmptyView()
                    } currentValueLabel: {
                        EmptyView()
                    }
                    .tint(state.phase.tint)
                    .padding(.top, 1)
                }
            }

            Spacer(minLength: 8)

            TimerLabel(state: state)
                .font(.system(.title, design: .rounded, weight: .semibold))
                .foregroundStyle(state.phase.tint)
        }
        .padding()
    }
}

// MARK: - Timer helpers

/// Picks the right live timer for the phase: a count-down for rest / timed work / auto-Done, a
/// stopwatch count-up for a rep-based work set, a checkmark for the terminal Done state, and
/// nothing for the Ready lead-in.
private struct TimerLabel: View {
    let state: WorkoutActivityAttributes.ContentState

    var body: some View {
        if let end = state.phaseEnd {
            CountdownText(start: state.phaseStart, end: end)
        } else if state.phase == .work {
            Text(state.phaseStart, style: .timer)
                .monospacedDigit()
        } else if state.phase == .done {
            Image(systemName: "checkmark.circle.fill")
                .foregroundStyle(.green)
        }
    }
}

/// A self-updating count-down rendered off wall-clock anchors — no push needed.
private struct CountdownText: View {
    let start: Date
    let end: Date

    var body: some View {
        Text(timerInterval: start...end, countsDown: true)
            .monospacedDigit()
            .multilineTextAlignment(.trailing)
    }
}

// MARK: - Styling

private enum Glyph {
    static let exercise = "figure.strengthtraining.traditional"
}

private extension WorkoutActivityAttributes.ContentState.Phase {
    /// Phase tint echoing the in-app run flow (brand purple for work, teal for rest). Kept
    /// local to the widget so the extension stays self-contained; values mirror
    /// `Color.workTint` / `Color.restTint` in `Shared/Utils/Color+Extensions.swift`.
    var tint: Color {
        switch self {
        case .ready: return Color(red: 0.51, green: 0.22, blue: 0.84)
        case .work:  return Color(red: 0.51, green: 0.22, blue: 0.84)
        case .rest:  return Color(red: 0.44, green: 0.85, blue: 0.84)
        case .done:  return .green
        }
    }
}