//
//  CreateViewModels.swift
//  Werkout_ios
//
//  Created by Trey Tartt on 6/18/23.
//

import Combine
import Foundation
import SharedCore

class CreateWorkoutExercise: ObservableObject, Identifiable {
    let id = UUID()
    var exercise: Exercise
    @Published var reps: Int = 0
    @Published var duration: Int = 0
    @Published var weight: Int = 0
    
    init(exercise: Exercise, reps: Int = 0, duration: Int = 0, weight: Int = 0) {
        self.exercise = exercise
        self.reps = reps
        self.duration = duration
        self.weight = weight
    }
    
    func increaseReps() {
        self.reps += 1
    }
    
    func decreaseReps() {
        self.reps -= 1
        if self.reps < 0 {
            self.reps = 0
        }
    }
    
    func increaseDuration() {
        self.duration += 15
        self.reps = 0
    }
    
    func decreaseDuration() {
        self.duration -= 15
        if self.duration < 0 {
            self.duration = 0
        }
    }
    
    func increaseWeight() {
        self.weight += 5
    }
    
    func decreaseWeight() {
        self.weight -= 5
        if self.weight < 0 {
            self.weight = 0
        }
    }
}

class CreateWorkoutSuperSet: ObservableObject, Identifiable, Equatable {
    static func == (lhs: CreateWorkoutSuperSet, rhs: CreateWorkoutSuperSet) -> Bool {
        lhs.id == rhs.id
    }
    
    let id = UUID()
    @Published var title: String = ""
    @Published var exercises = [CreateWorkoutExercise]()
    @Published var numberOfRounds = 0
    
    func increaseNumberOfRounds() {
        self.numberOfRounds += 1
    }
    
    func decreaseNumberOfRounds() {
        self.numberOfRounds -= 1
        if self.numberOfRounds < 0 {
            self.numberOfRounds = 0
        }
    }
    
    func deleteExerciseForChosenSuperset(exercise: CreateWorkoutExercise) {
        if let idx = exercises.firstIndex(where: {
            $0.id == exercise.id
        }) {
            exercises.remove(at: idx)
        }
    }
}

class WorkoutViewModel: ObservableObject {
    @Published var superSets = [CreateWorkoutSuperSet]()
    @Published var title = String()
    @Published var description = String()
    @Published var validationError: String?
    @Published var isUploading = false
    // MARK: - Manual Invalidation
    // Workaround: nested ObservableObject changes don't propagate to parent.
    // Remove when migrating to @Observable (iOS 17+).
    @Published var randomValueForUpdatingValue = 0
    
    func increaseRandomNumberForUpdating() {
        randomValueForUpdatingValue += 1
    }
    
    func addNewSuperset() {
        increaseRandomNumberForUpdating()
        superSets.append(CreateWorkoutSuperSet())
    }
    
    func delete(superset: CreateWorkoutSuperSet) {
        if let idx = superSets.firstIndex(where: {
            $0.id == superset.id
        }) {
            superSets.remove(at: idx)
            increaseRandomNumberForUpdating()
        }
    }

    func addExercise(_ exercise: Exercise, to superset: CreateWorkoutSuperSet) {
        let workoutExercise = CreateWorkoutExercise(exercise: exercise)
        superset.exercises.append(workoutExercise)

        if exercise.side?.isEmpty == false {
            autoAddSiblingExercises(for: exercise, to: superset)
        }
        increaseRandomNumberForUpdating()
    }

    private func autoAddSiblingExercises(for exercise: Exercise, to superset: CreateWorkoutSuperSet) {
        guard let allExercises = DataStore.shared.allExercise else { return }
        let siblings = allExercises.filter { $0.name == exercise.name }
        guard siblings.count == 2,
              let recover = allExercises.first(where: { $0.name.lowercased() == "recover" }) else { return }

        let recoverExercise = CreateWorkoutExercise(exercise: recover)
        superset.exercises.append(recoverExercise)

        for sibling in siblings where sibling.id != exercise.id {
            let otherSideExercise = CreateWorkoutExercise(exercise: sibling)
            superset.exercises.append(otherSideExercise)
        }
    }

    func showRoundsError() {
        validationError = "Each superset must have at least one round."
    }
    
    func showNoDurationOrReps() {
        validationError = "Each exercise must have reps or duration."
    }
    
    func uploadWorkout() {
        guard isUploading == false else {
            return
        }

        validationError = nil
        let normalizedTitle = title.trimmingCharacters(in: .whitespacesAndNewlines)
        guard normalizedTitle.isEmpty == false else {
            validationError = "Workout title is required."
            return
        }
        
        var supersets = [[String: Any]]()
        for (supersetOffset, superset) in superSets.enumerated() {
            var supersetInfo = [String: Any]()
            supersetInfo["name"] = ""
            supersetInfo["rounds"] = superset.numberOfRounds
            supersetInfo["order"] = supersetOffset + 1
            
            var exercises = [[String: Any]]()
            for (exerciseOffset, exercise) in superset.exercises.enumerated() {
                let item = ["id": exercise.exercise.id,
                            "reps": exercise.reps,
                            "weight": exercise.weight,
                            "duration": exercise.duration,
                            "order": exerciseOffset + 1] as [String : Any]
                exercises.append(item)
            }
            supersetInfo["exercises"] = exercises
            
            supersets.append(supersetInfo)
        }
        
        if supersets.isEmpty {
            validationError = "Add at least one superset before uploading."
            return
        }

        let issues = WorkoutValidation.validateSupersets(supersets)
        if let issue = issues.first {
            switch issue.code {
            case "invalid_rounds":
                showRoundsError()
            case "invalid_exercise_payload":
                showNoDurationOrReps()
            default:
                validationError = issue.message
            }
            return
        }
        
        let uploadBody = ["name": normalizedTitle,
                          "description": description,
                          "supersets": supersets] as [String : Any]
        isUploading = true
        CreateWorkoutFetchable(postData: uploadBody).fetch(completion: { result in
            self.isUploading = false
            switch result {
            case .success(_):
                self.superSets.removeAll()
                self.title = ""
                self.description = ""
                NotificationCenter.default.post(
                    name: AppNotifications.createdNewWorkout,
                    object: nil,
                    userInfo: nil
                )
            case .failure(let failure):
                self.validationError = "Failed to upload workout: \(failure.localizedDescription)"
            }
        })
    }
}