// ── Routine Editor View ───────────────────────────────────────
// Create or edit a routine with steps, durations, and transitions

import SwiftUI

struct RoutineEditorView: View {
    let routine: CMRoutine?
    let onSave: (CMRoutine) -> Void
    let onCancel: () -> Void

    @State private var name: String = ""
    @State private var description: String = ""
    @State private var steps: [CMRoutineStep] = []

    var body: some View {
        NavigationStack {
            ScrollView {
                VStack(spacing: 20) {
                    // Name & description
                    VStack(alignment: .leading, spacing: 8) {
                        Text("Name")
                            .font(.subheadline.bold())
                            .foregroundColor(CMColors.textSecondary)
                        TextField("Morning Routine", text: $name)
                            .textFieldStyle(.plain)
                            .padding(10)
                            .background(CMColors.surfaceHover)
                            .cornerRadius(8)
                            .foregroundColor(CMColors.text)

                        Text("Description")
                            .font(.subheadline.bold())
                            .foregroundColor(CMColors.textSecondary)
                        TextField("Start your day with intention", text: $description)
                            .textFieldStyle(.plain)
                            .padding(10)
                            .background(CMColors.surfaceHover)
                            .cornerRadius(8)
                            .foregroundColor(CMColors.text)
                    }

                    // Steps
                    VStack(alignment: .leading, spacing: 8) {
                        HStack {
                            Text("Steps")
                                .font(.subheadline.bold())
                                .foregroundColor(CMColors.textSecondary)
                            Spacer()
                            Text("\(totalDuration) min total")
                                .font(.caption)
                                .foregroundColor(CMColors.accent)
                        }

                        ForEach(Array(steps.enumerated()), id: \.element.id) { idx, step in
                            stepRow(step, index: idx)
                        }

                        Button {
                            steps.append(CMRoutineStep(
                                label: "",
                                durationMinutes: 10
                            ))
                        } label: {
                            Label("Add Step", systemImage: "plus.circle.fill")
                                .font(.subheadline)
                                .foregroundColor(CMColors.accent)
                        }
                        .padding(.top, 4)
                    }
                }
                .padding()
            }
            .background(CMColors.bg.ignoresSafeArea())
            .navigationTitle(routine == nil ? "New Routine" : "Edit Routine")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("Cancel") { onCancel() }
                        .foregroundColor(CMColors.textSecondary)
                }
                ToolbarItem(placement: .confirmationAction) {
                    Button("Save") { save() }
                        .foregroundColor(CMColors.accent)
                        .disabled(name.trimmingCharacters(in: .whitespaces).isEmpty || steps.isEmpty)
                }
            }
            .onAppear {
                if let r = routine {
                    name = r.name
                    description = r.routineDescription ?? ""
                    steps = r.steps
                }
            }
        }
    }

    // MARK: - Step Row

    @ViewBuilder
    private func stepRow(_ step: CMRoutineStep, index: Int) -> some View {
        VStack(spacing: 8) {
            HStack(spacing: 8) {
                // Drag handle / index
                Text("\(index + 1)")
                    .font(.caption.bold())
                    .foregroundColor(CMColors.textMuted)
                    .frame(width: 20)

                // Label
                TextField("Step name", text: Binding(
                    get: { steps[safe: index]?.label ?? "" },
                    set: { if steps.indices.contains(index) { steps[index].label = $0 } }
                ))
                .textFieldStyle(.plain)
                .padding(8)
                .background(CMColors.surfaceHover)
                .cornerRadius(6)
                .foregroundColor(CMColors.text)
                .font(.subheadline)

                // Duration stepper
                HStack(spacing: 4) {
                    Button {
                        if steps.indices.contains(index) && steps[index].durationMinutes > 1 {
                            steps[index].durationMinutes -= 1
                        }
                    } label: {
                        Image(systemName: "minus")
                            .font(.caption2)
                            .foregroundColor(CMColors.textSecondary)
                    }

                    Text("\(steps[safe: index]?.durationMinutes ?? 0)m")
                        .font(.caption.monospacedDigit())
                        .foregroundColor(CMColors.accent)
                        .frame(width: 30)

                    Button {
                        if steps.indices.contains(index) {
                            steps[index].durationMinutes += 1
                        }
                    } label: {
                        Image(systemName: "plus")
                            .font(.caption2)
                            .foregroundColor(CMColors.textSecondary)
                    }
                }
                .padding(.horizontal, 8)
                .padding(.vertical, 4)
                .background(CMColors.surface)
                .cornerRadius(6)

                // Delete
                Button {
                    steps.remove(at: index)
                } label: {
                    Image(systemName: "trash")
                        .font(.caption)
                        .foregroundColor(CMColors.critical.opacity(0.7))
                }
            }

            // Transition picker (not on last step)
            if index < steps.count - 1 {
                HStack(spacing: 8) {
                    Spacer().frame(width: 20)
                    Image(systemName: "arrow.down")
                        .font(.caption2)
                        .foregroundColor(CMColors.textMuted)

                    Picker("Transition", selection: Binding(
                        get: { steps[safe: index]?.transition ?? .immediate },
                        set: { if steps.indices.contains(index) { steps[index].transition = $0 } }
                    )) {
                        ForEach(TransitionType.allCases) { t in
                            Text(t.label).tag(t)
                        }
                    }
                    .pickerStyle(.menu)
                    .tint(CMColors.textSecondary)
                    .font(.caption)

                    Spacer()
                }
            }

            // Notes
            TextField("Notes (optional)", text: Binding(
                get: { steps[safe: index]?.notes ?? "" },
                set: { if steps.indices.contains(index) { steps[index].notes = $0.isEmpty ? nil : $0 } }
            ))
            .textFieldStyle(.plain)
            .padding(6)
            .background(CMColors.surfaceHover.opacity(0.5))
            .cornerRadius(4)
            .foregroundColor(CMColors.textMuted)
            .font(.caption)
            .padding(.leading, 28)
        }
        .padding(10)
        .background(CMColors.surface)
        .cornerRadius(8)
    }

    // MARK: - Computed

    private var totalDuration: Int {
        CMRoutine.calculateTotalDuration(steps: steps)
    }

    // MARK: - Actions

    private func save() {
        let trimmedName = name.trimmingCharacters(in: .whitespaces)
        guard !trimmedName.isEmpty, !steps.isEmpty else { return }

        let validSteps = steps.filter { !$0.label.trimmingCharacters(in: .whitespaces).isEmpty }
        guard !validSteps.isEmpty else { return }

        if var existing = routine {
            existing.name = trimmedName
            existing.routineDescription = description.isEmpty ? nil : description
            existing.steps = validSteps
            existing.totalDurationMinutes = CMRoutine.calculateTotalDuration(steps: validSteps)
            onSave(existing)
        } else {
            let newRoutine = CMRoutine(
                name: trimmedName,
                routineDescription: description.isEmpty ? nil : description,
                steps: validSteps
            )
            onSave(newRoutine)
        }
    }
}

// MARK: - Safe Array Subscript

private extension Array {
    subscript(safe index: Int) -> Element? {
        indices.contains(index) ? self[index] : nil
    }
}