//
// RoutineAddEditView.swift
// Workouts
//
// Created by rzen on 7/18/25 at 9:42 AM.
//
// Copyright 2025 Rouslan Zenetl. All Rights Reserved.
//

import IndieSync
import SwiftUI
import SwiftData

struct RoutineAddEditView: View {
    @Environment(SyncEngine.self) private var sync
    @Environment(\.modelContext) private var modelContext
    @Environment(\.dismiss) private var dismiss

    // Resolve the routine by id, not a captured entity: a clone-on-edit swaps a seed's
    // identity mid-screen (the seed entity is deleted and a clone inserted), which
    // would dangle a stored `Routine`. `currentRoutineID` follows that swap. `routineID` is
    // nil in create mode.
    @State private var routineID: String?
    @Query private var routines: [Routine]

    var onDelete: (() -> Void)?

    @State private var name: String = ""
    @State private var color: String = "indigo"
    @State private var systemImage: String = "dumbbell.fill"
    @State private var activityType: WorkoutActivityType = .traditionalStrength
    @State private var autoAdvance: Bool = false
    @State private var restOverrideEnabled: Bool = false
    @State private var restSecondsValue: Int = 45
    @State private var targetHREnabled: Bool = false
    @State private var targetHRValue: Int = 135
    @State private var showingIconPicker: Bool = false
    @State private var showingDeleteConfirmation: Bool = false

    var isEditing: Bool { routineID != nil }

    init(routine: Routine?, onDelete: (() -> Void)? = nil) {
        _routineID = State(initialValue: routine?.id)
        self.onDelete = onDelete
        if let routine = routine {
            _name = State(initialValue: routine.name)
            _color = State(initialValue: routine.color)
            _systemImage = State(initialValue: routine.systemImage)
            _activityType = State(initialValue: routine.activityTypeEnum)
            _autoAdvance = State(initialValue: routine.autoAdvance ?? false)
            _restOverrideEnabled = State(initialValue: routine.restSeconds != nil)
            _restSecondsValue = State(initialValue: routine.restSeconds ?? 45)
            _targetHREnabled = State(initialValue: routine.targetHeartRate != nil)
            _targetHRValue = State(initialValue: routine.targetHeartRate ?? 135)
        }
    }

    private var routine: Routine? {
        guard let routineID else { return nil }
        let id = sync.currentRoutineID(for: routineID)
        return routines.first { $0.id == id }
    }

    var body: some View {
        NavigationStack {
            if isEditing && routine == nil {
                // The id we held no longer maps to a live routine (deleted on another
                // device, or a transient mid-clone frame). Show nothing and leave.
                ContentUnavailableView("Routine Unavailable", systemImage: "dumbbell")
                    .task { dismiss() }
            } else {
                form(for: routine)
            }
        }
    }

    @ViewBuilder
    private func form(for routine: Routine?) -> some View {
        Form {
            Section {
                TextField("Name", text: $name)
                    .bold()
            } header: {
                Text("Name")
            } footer: {
                if let routineID, SeedLibrary.isSeed(id: routineID) {
                    Text("Saving changes to a starter routine creates your own copy; the starter stays available in the gallery.")
                }
            }

            Section(header: Text("Appearance")) {
                Picker("Color", selection: $color) {
                    ForEach(availableColors, id: \.self) { colorName in
                        HStack {
                            Circle()
                                .fill(Color.color(from: colorName))
                                .frame(width: 20, height: 20)
                            Text(colorName.capitalized)
                        }
                        .tag(colorName)
                    }
                }

                Button {
                    showingIconPicker = true
                } label: {
                    HStack {
                        Text("Icon")
                            .foregroundColor(.primary)
                        Spacer()
                        Image(systemName: systemImage)
                            .font(.title2)
                            .foregroundColor(.accentColor)
                    }
                }
            }

            Section {
                Picker("Activity Type", selection: $activityType) {
                    ForEach(WorkoutActivityType.allCases, id: \.self) { type in
                        Label(type.displayName, systemImage: type.systemImage).tag(type)
                    }
                }
            } header: {
                Text("Activity Type")
            } footer: {
                Text("Determines how this workout is categorized in Apple Health and how it credits your Activity rings.")
            }

            Section {
                Toggle("Auto-Advance Exercises", isOn: $autoAdvance)

                Toggle("Custom Rest Time", isOn: $restOverrideEnabled)
                if restOverrideEnabled {
                    SecondsStepperRow(title: "Rest Time", range: 10...180, seconds: $restSecondsValue)
                }
            } header: {
                Text("Rest & Pacing")
            } footer: {
                Text("Auto-Advance flows from one exercise to the next with a rest between, so you can run the whole routine hands-free. Custom Rest Time sets this routine's rest — used between sets, and between exercises when auto-advancing; otherwise the Settings default applies.")
            }

            // Only endurance types get a target — a strength set's HR swings by design.
            if activityType.supportsHeartRateTarget {
                Section {
                    Toggle("Target Heart Rate", isOn: $targetHREnabled)
                    if targetHREnabled {
                        Stepper(value: $targetHRValue, in: 80...200, step: 5) {
                            HStack {
                                Text("Target")
                                Spacer()
                                Text("\(targetHRValue) bpm").foregroundColor(.secondary)
                            }
                        }
                    }
                } header: {
                    Text("Heart Rate")
                } footer: {
                    Text("During a run, the exercise screen shows your live heart rate from the watch with a cue to ease off or push harder — useful for holding a steady effort, like dialing in a treadmill incline.")
                }
            }

            if routine != nil {
                Section {
                    Button("Delete Routine", role: .destructive) {
                        showingDeleteConfirmation = true
                    }
                }
            }
        }
        .navigationTitle(isEditing ? "Edit Routine" : "New Routine")
        .toolbar {
            ToolbarItem(placement: .navigationBarLeading) {
                Button("Cancel") {
                    dismiss()
                }
            }

            ToolbarItem(placement: .navigationBarTrailing) {
                Button("Save") {
                    save()
                    dismiss()
                }
                .disabled(name.isEmpty)
            }
        }
        .sheet(isPresented: $showingIconPicker) {
            SFSymbolPicker(selection: $systemImage)
        }
        .confirmationDialog(
            "Delete This Routine?",
            isPresented: $showingDeleteConfirmation,
            titleVisibility: .visible
        ) {
            Button("Delete", role: .destructive) {
                if let routine = routine {
                    Task {
                        await sync.delete(routine: routine)
                    }
                    dismiss()
                    onDelete?()
                }
            }
        } message: {
            Text("This will permanently delete the routine and all its exercises.")
        }
    }

    private func save() {
        if isEditing {
            // Update existing routine. If the id no longer resolves (deleted remotely
            // mid-edit), there's nothing to save.
            guard let routine = routine else { return }
            var doc = RoutineDocument(from: routine)
            doc.name = name
            doc.color = color
            doc.systemImage = systemImage
            doc.activityType = activityType.rawValue
            doc.restSeconds = restOverrideEnabled ? restSecondsValue : nil
            doc.autoAdvance = autoAdvance ? true : nil
            // Cleared when the type no longer supports a target (the section hides).
            doc.targetHeartRate = activityType.supportsHeartRateTarget && targetHREnabled
                ? targetHRValue : nil
            doc.updatedAt = Date()
            Task { await sync.save(routine: doc) }
        } else {
            // Create new routine
            let existing = (try? modelContext.fetch(FetchDescriptor<Routine>())) ?? []
            let doc = RoutineDocument(
                schemaVersion: RoutineDocument.currentSchemaVersion,
                id: ULID.make(),
                name: name,
                color: color,
                systemImage: systemImage,
                order: existing.count,
                createdAt: Date(),
                updatedAt: Date(),
                exercises: [],
                activityType: activityType.rawValue,
                restSeconds: restOverrideEnabled ? restSecondsValue : nil,
                autoAdvance: autoAdvance ? true : nil,
                targetHeartRate: activityType.supportsHeartRateTarget && targetHREnabled
                    ? targetHRValue : nil
            )
            Task { await sync.save(routine: doc) }
        }
    }
}