//
// ExerciseView.swift
// Workouts
//
// Created by rzen on 7/18/25 at 5:44 PM.
//
// Copyright 2025 Rouslan Zenetl. All Rights Reserved.
//

import SwiftUI
import CoreData
import Charts

struct ExerciseView: View {
    @Environment(\.managedObjectContext) private var viewContext
    @Environment(\.dismiss) private var dismiss

    @ObservedObject var workoutLog: WorkoutLog

    var allLogs: [WorkoutLog]
    var currentIndex: Int = 0

    @State private var progress: Int = 0
    @State private var navigateTo: WorkoutLog? = nil

    let notStartedColor = Color.white
    let completedColor = Color.green

    var body: some View {
        Form {
            Section(header: Text("Navigation")) {
                HStack {
                    Button(action: navigateToPrevious) {
                        HStack {
                            Image(systemName: "chevron.left")
                            Text("Previous")
                        }
                    }
                    .disabled(currentIndex <= 0)

                    Spacer()
                    Text("\(currentIndex + 1) of \(allLogs.count)")
                        .foregroundColor(.secondary)
                    Spacer()

                    Button(action: navigateToNext) {
                        HStack {
                            Text("Next")
                            Image(systemName: "chevron.right")
                        }
                    }
                    .disabled(currentIndex >= allLogs.count - 1)
                }
                .padding(.vertical, 8)
            }

            Section(header: Text("Progress")) {
                LazyVGrid(columns: Array(repeating: GridItem(.flexible()), count: Int(workoutLog.sets)), spacing: 2) {
                    ForEach(1...Int(workoutLog.sets), id: \.self) { index in
                        ZStack {
                            let completed = index <= progress
                            let color = completed ? completedColor : notStartedColor
                            RoundedRectangle(cornerRadius: 8)
                                .fill(
                                    LinearGradient(
                                        gradient: Gradient(colors: [color, color.darker(by: 0.2)]),
                                        startPoint: .topLeading,
                                        endPoint: .bottomTrailing
                                    )
                                )
                                .aspectRatio(0.618, contentMode: .fit)
                                .shadow(radius: 2)
                            Text("\(index)")
                                .foregroundColor(.primary)
                                .colorInvert()
                        }
                        .onTapGesture {
                            if progress == index {
                                progress = 0
                            } else {
                                progress = index
                            }
                            updateLogStatus()
                        }
                    }
                }
            }

            Section(header: Text("Plan")) {
                Stepper("\(workoutLog.sets) sets", value: Binding(
                    get: { Int(workoutLog.sets) },
                    set: { workoutLog.sets = Int32($0) }
                ), in: 1...10)
                    .font(.title)

                Stepper("\(workoutLog.reps) reps", value: Binding(
                    get: { Int(workoutLog.reps) },
                    set: { workoutLog.reps = Int32($0) }
                ), in: 1...25)
                    .font(.title)

                HStack {
                    Text("\(workoutLog.weight) lbs")
                    VStack(alignment: .trailing) {
                        Stepper("", value: Binding(
                            get: { Int(workoutLog.weight) },
                            set: { workoutLog.weight = Int32($0) }
                        ), in: 1...500)
                        Stepper("", value: Binding(
                            get: { Int(workoutLog.weight) },
                            set: { workoutLog.weight = Int32($0) }
                        ), in: 1...500, step: 5)
                    }
                }
                .font(.title)
            }

            Section(header: Text("Progress Tracking")) {
                WeightProgressionChartView(exerciseName: workoutLog.exerciseName)
            }
        }
        .navigationTitle(workoutLog.exerciseName)
        .navigationDestination(item: $navigateTo) { nextLog in
            ExerciseView(
                workoutLog: nextLog,
                allLogs: allLogs,
                currentIndex: allLogs.firstIndex(where: { $0.objectID == nextLog.objectID }) ?? 0
            )
        }
        .onAppear {
            progress = Int(workoutLog.currentStateIndex)
        }
        .onDisappear {
            saveChanges()
        }
    }

    private func updateLogStatus() {
        workoutLog.currentStateIndex = Int32(progress)
        if progress >= Int(workoutLog.sets) {
            workoutLog.status = .completed
        } else if progress > 0 {
            workoutLog.status = .inProgress
        } else {
            workoutLog.status = .notStarted
        }
        saveChanges()
    }

    private func saveChanges() {
        try? viewContext.save()
    }

    private func navigateToPrevious() {
        guard currentIndex > 0 else { return }
        let previousIndex = currentIndex - 1
        navigateTo = allLogs[previousIndex]
    }

    private func navigateToNext() {
        guard currentIndex < allLogs.count - 1 else { return }
        let nextIndex = currentIndex + 1
        navigateTo = allLogs[nextIndex]
    }
}