//
//  GuidedReflectionView.swift
//  Reflect
//
//  Card-step guided reflection sheet — one question at a time.
//

import SwiftUI

struct GuidedReflectionView: View {

    @Environment(\.dismiss) private var dismiss
    @AppStorage(UserDefaultsStore.Keys.theme.rawValue, store: GroupUserDefaults.groupDefaults) private var theme: Theme = .system
    @AppStorage(UserDefaultsStore.Keys.moodImages.rawValue, store: GroupUserDefaults.groupDefaults) private var imagePack: MoodImages = .FontAwesome
    @AppStorage(UserDefaultsStore.Keys.moodTint.rawValue, store: GroupUserDefaults.groupDefaults) private var moodTint: MoodTints = .Default

    let entry: MoodEntryModel

    @State private var reflection: GuidedReflection
    @State private var currentStep: Int = 0
    @State private var isSaving = false
    @State private var showDiscardAlert = false
    @FocusState private var isTextFieldFocused: Bool

    /// Snapshot of the initial state to detect unsaved changes
    private let initialReflection: GuidedReflection

    private let maxCharacters = 500

    private var textColor: Color { theme.currentTheme.labelColor }

    private var totalSteps: Int { reflection.totalQuestions }

    private var hasUnsavedChanges: Bool {
        reflection != initialReflection
    }

    init(entry: MoodEntryModel) {
        self.entry = entry
        let existing = entry.reflectionJSON.flatMap { GuidedReflection.decode(from: $0) }
            ?? GuidedReflection.createNew(for: entry.mood)
        self._reflection = State(initialValue: existing)
        self.initialReflection = existing
    }

    var body: some View {
        NavigationStack {
            VStack(spacing: 0) {
                // Entry header
                entryHeader
                    .padding()
                    .background(Color(.systemGray6))

                Divider()

                // Progress dots
                progressDots
                    .padding(.top, 20)
                    .padding(.bottom, 8)

                // Question + answer area
                questionContent
                    .padding(.horizontal)

                Spacer()

                // Navigation buttons
                navigationButtons
                    .padding()
            }
            .navigationTitle(String(localized: "guided_reflection_title"))
            .navigationBarTitleDisplayMode(.inline)
            .accessibilityIdentifier(AccessibilityID.GuidedReflection.sheet)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button(String(localized: "Cancel")) {
                        if hasUnsavedChanges {
                            showDiscardAlert = true
                        } else {
                            dismiss()
                        }
                    }
                    .accessibilityIdentifier(AccessibilityID.GuidedReflection.cancelButton)
                }

                ToolbarItemGroup(placement: .keyboard) {
                    Spacer()
                    Button("Done") {
                        isTextFieldFocused = false
                    }
                }
            }
            .alert(
                String(localized: "guided_reflection_unsaved_title"),
                isPresented: $showDiscardAlert
            ) {
                Button(String(localized: "guided_reflection_discard"), role: .destructive) {
                    dismiss()
                }
                Button(String(localized: "Cancel"), role: .cancel) { }
            } message: {
                Text(String(localized: "guided_reflection_unsaved_message"))
            }
            .trackScreen(.guidedReflection)
        }
    }

    // MARK: - Entry Header

    private var entryHeader: some View {
        HStack(spacing: 12) {
            Circle()
                .fill(moodTint.color(forMood: entry.mood).opacity(0.2))
                .frame(width: 50, height: 50)
                .overlay(
                    imagePack.icon(forMood: entry.mood)
                        .resizable()
                        .aspectRatio(contentMode: .fit)
                        .frame(width: 28, height: 28)
                        .foregroundColor(moodTint.color(forMood: entry.mood))
                )

            VStack(alignment: .leading, spacing: 4) {
                Text(entry.forDate, format: .dateTime.weekday(.wide).month().day().year())
                    .font(.headline)
                    .foregroundColor(textColor)

                Text(entry.moodString)
                    .font(.subheadline)
                    .foregroundColor(moodTint.color(forMood: entry.mood))
            }

            Spacer()
        }
    }

    // MARK: - Progress Dots

    private var progressDots: some View {
        HStack(spacing: 8) {
            ForEach(0..<totalSteps, id: \.self) { index in
                Circle()
                    .fill(index == currentStep ? moodTint.color(forMood: entry.mood) : Color(.systemGray4))
                    .frame(width: 10, height: 10)
            }
        }
        .accessibilityIdentifier(AccessibilityID.GuidedReflection.progressDots)
    }

    // MARK: - Question Content

    private var questionContent: some View {
        VStack(alignment: .leading, spacing: 16) {
            if currentStep < reflection.responses.count {
                let response = reflection.responses[currentStep]

                Text(response.question)
                    .font(.title3)
                    .fontWeight(.medium)
                    .foregroundColor(textColor)
                    .fixedSize(horizontal: false, vertical: true)
                    .accessibilityIdentifier(AccessibilityID.GuidedReflection.questionLabel(step: currentStep))
                    .id("question_\(currentStep)")

                TextEditor(text: $reflection.responses[currentStep].answer)
                    .focused($isTextFieldFocused)
                    .frame(minHeight: 120, maxHeight: 200)
                    .scrollContentBackground(.hidden)
                    .padding(12)
                    .background(
                        RoundedRectangle(cornerRadius: 12)
                            .fill(Color(.systemBackground))
                    )
                    .overlay(
                        RoundedRectangle(cornerRadius: 12)
                            .stroke(Color(.systemGray4), lineWidth: 1)
                    )
                    .onChange(of: reflection.responses[currentStep].answer) { _, newValue in
                        if newValue.count > maxCharacters {
                            reflection.responses[currentStep].answer = String(newValue.prefix(maxCharacters))
                        }
                    }
                    .accessibilityIdentifier(AccessibilityID.GuidedReflection.textEditor)

                HStack {
                    Spacer()
                    Text("\(reflection.responses[currentStep].answer.count)/\(maxCharacters)")
                        .font(.caption)
                        .foregroundStyle(
                            reflection.responses[currentStep].answer.count >= maxCharacters ? .red : .secondary
                        )
                }
            }
        }
    }

    // MARK: - Navigation Buttons

    private var navigationButtons: some View {
        HStack {
            // Back button
            if currentStep > 0 {
                Button {
                    navigateBack()
                } label: {
                    HStack(spacing: 4) {
                        Image(systemName: "chevron.left")
                        Text(String(localized: "guided_reflection_back"))
                    }
                    .font(.body)
                    .fontWeight(.medium)
                }
                .accessibilityIdentifier(AccessibilityID.GuidedReflection.backButton)
            }

            Spacer()

            // Next / Save button
            if currentStep < totalSteps - 1 {
                Button {
                    navigateForward()
                } label: {
                    HStack(spacing: 4) {
                        Text(String(localized: "guided_reflection_next"))
                        Image(systemName: "chevron.right")
                    }
                    .font(.body)
                    .fontWeight(.semibold)
                }
                .accessibilityIdentifier(AccessibilityID.GuidedReflection.nextButton)
            } else {
                Button {
                    saveReflection()
                } label: {
                    Text(String(localized: "guided_reflection_save"))
                        .font(.body)
                        .fontWeight(.semibold)
                }
                .disabled(isSaving)
                .accessibilityIdentifier(AccessibilityID.GuidedReflection.saveButton)
            }
        }
    }

    // MARK: - Navigation

    private func navigateForward() {
        isTextFieldFocused = false
        let animate = !UIAccessibility.isReduceMotionEnabled
        if animate {
            withAnimation(.easeInOut(duration: 0.3)) {
                currentStep += 1
            }
        } else {
            currentStep += 1
        }
        focusTextFieldDelayed()
    }

    private func navigateBack() {
        isTextFieldFocused = false
        let animate = !UIAccessibility.isReduceMotionEnabled
        if animate {
            withAnimation(.easeInOut(duration: 0.3)) {
                currentStep -= 1
            }
        } else {
            currentStep -= 1
        }
        focusTextFieldDelayed()
    }

    private func focusTextFieldDelayed() {
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
            isTextFieldFocused = true
        }
    }

    // MARK: - Save

    private func saveReflection() {
        isSaving = true

        if reflection.isComplete {
            reflection.completedAt = Date()
        }

        let json = reflection.encode()
        let success = DataController.shared.updateReflection(forDate: entry.forDate, reflectionJSON: json)

        if success {
            dismiss()
        } else {
            isSaving = false
        }
    }
}