//
//  WorkoutView.swift
//  Keging
//
//  운동 진행 화면 — 국면 원이 수축 때 줄고 이완 때 커진다. 중단 시 이 세트는 기록 없음.
//

import SwiftUI

struct WorkoutView: View {
    @EnvironmentObject private var engine: KegelEngine
    @State private var confirmStop = false

    var body: some View {
        ZStack {
            AppTheme.background.ignoresSafeArea()
            switch engine.state {
            case let .running(phase, rep, phaseStart, phaseEnd):
                runningView(phase: phase, rep: rep, phaseStart: phaseStart, phaseEnd: phaseEnd)
            case let .finished(reps):
                finishedView(reps: reps)
            case .idle:
                Color.clear
            }
        }
    }

    private func runningView(phase: KegelPhase, rep: Int, phaseStart: Date, phaseEnd: Date) -> some View {
        VStack(spacing: 0) {
            Text("\(rep) / \(engine.config.reps)")
                .font(.title2.weight(.semibold))
                .monospacedDigit()
                .foregroundStyle(.secondary)
                .padding(.top, 24)
                .accessibilityLabel(Text("현재 \(rep)번째, 전체 \(engine.config.reps)회"))

            Spacer()

            ZStack {
                PhaseCircle(phase: phase, phaseStart: phaseStart, phaseEnd: phaseEnd)
                VStack(spacing: 6) {
                    Text(phase.label)
                        .font(.system(size: 44, weight: .bold))
                    Text(timerInterval: phaseStart...phaseEnd, countsDown: true)
                        .font(.title2.weight(.medium))
                        .monospacedDigit()
                        .opacity(0.85)
                }
                .foregroundStyle(Color(light: .white, dark: Color(hex: "#0F2018")))
            }

            Spacer()

            Button {
                confirmStop = true
            } label: {
                Text("중단")
                    .font(.headline)
                    .frame(maxWidth: 160)
            }
            .buttonStyle(.bordered)
            .tint(.red)
            .padding(.bottom, 30)
        }
        .confirmationDialog("운동을 중단할까요?", isPresented: $confirmStop, titleVisibility: .visible) {
            Button("중단하기", role: .destructive) { engine.stop() }
            Button("계속하기", role: .cancel) {}
        } message: {
            Text("중단하면 이 세트는 기록되지 않아요.")
        }
    }

    private func finishedView(reps: Int) -> some View {
        VStack(spacing: 18) {
            Image(systemName: "checkmark.circle.fill")
                .font(.system(size: 84))
                .foregroundStyle(AppTheme.green)
            Text("완료!")
                .font(.largeTitle.bold())
            Text("\(reps)회를 모두 마쳤어요.")
                .font(.body)
                .foregroundStyle(.secondary)
            Button {
                engine.acknowledgeFinish()
            } label: {
                Text("확인")
                    .font(.headline)
                    .frame(maxWidth: 160)
            }
            .buttonStyle(.borderedProminent)
            .padding(.top, 12)
        }
    }
}

/// 수축이면 오므라들고 이완이면 부풀어 오르는 국면 원
private struct PhaseCircle: View {
    let phase: KegelPhase
    let phaseStart: Date
    let phaseEnd: Date

    @State private var scale: CGFloat = 1

    var body: some View {
        Circle()
            .fill(
                LinearGradient(
                    colors: [AppTheme.green, AppTheme.green.opacity(0.8)],
                    startPoint: .top, endPoint: .bottom
                )
            )
            .frame(width: 300, height: 300)
            .scaleEffect(scale)
            .shadow(color: AppTheme.green.opacity(0.3), radius: 26, x: 0, y: 10)
            .onAppear { animate() }
            .onChange(of: phase) { animate() }
    }

    private func animate() {
        let duration = max(0.3, phaseEnd.timeIntervalSince(phaseStart))
        var transaction = Transaction()
        transaction.disablesAnimations = true
        withTransaction(transaction) {
            scale = phase == .contract ? 1.0 : 0.62
        }
        withAnimation(.easeInOut(duration: duration)) {
            scale = phase == .contract ? 0.62 : 1.0
        }
    }
}