Spanish/Conjuga/Conjuga/Views/Practice/Vocab/VocabMultipleChoicePracticeView.swift

import SwiftUI
import SharedModels
import SwiftData

/// English-first verb multiple choice. Pool = verbs whose `level` is enabled
/// in Settings (UserProgress.selectedVerbLevels). 4 options shown, 1 correct
/// + 3 random distractors from the same pool. After answer: reveal correct/
/// incorrect, the verb infinitive, an AI illustration, an example sentence,
/// and SRS rating buttons.
struct VocabMultipleChoicePracticeView: View {
    @Environment(\.modelContext) private var localContext
    @Environment(\.cloudModelContextProvider) private var cloudModelContextProvider
    @Environment(VerbExampleCache.self) private var exampleCache
    @Environment(\.dismiss) private var dismiss

    @State private var verbs: [Verb] = []
    @State private var index: Int = 0
    @State private var options: [Verb] = []
    @State private var selectedOption: Verb? = nil
    @State private var exampleByVerbId: [Int: VerbExample] = [:]
    @State private var generatingExampleForVerbId: Int? = nil

    private var cloudContext: ModelContext { cloudModelContextProvider() }

    private var currentVerb: Verb? {
        guard index < verbs.count else { return nil }
        return verbs[index]
    }

    var body: some View {
        ScrollView {
            VStack(spacing: 22) {
                progressBar
                if let verb = currentVerb {
                    questionBody(verb)
                } else {
                    completionView
                }
            }
            .padding()
            .adaptiveContainer(maxWidth: 720)
        }
        .navigationTitle("Vocab Multiple Choice")
        .navigationBarTitleDisplayMode(.inline)
        .onAppear(perform: loadIfNeeded)
        .animation(.smooth, value: selectedOption?.id)
        .animation(.smooth, value: index)
    }

    // MARK: - Progress

    private var progressBar: some View {
        VStack(spacing: 6) {
            ProgressView(value: verbs.isEmpty ? 0 : Double(index) / Double(verbs.count))
                .tint(.purple)
            Text(verbs.isEmpty ? "No verbs match the levels enabled in Settings" : "\(min(index + 1, verbs.count)) of \(verbs.count)")
                .font(.caption)
                .foregroundStyle(.secondary)
        }
    }

    // MARK: - Question

    @ViewBuilder
    private func questionBody(_ verb: Verb) -> some View {
        Text("to \(verb.english)")
            .font(.largeTitle.weight(.bold))
            .multilineTextAlignment(.center)
            .padding(.top, 12)

        if selectedOption == nil {
            optionGrid
        } else {
            revealedContent(verb)
        }
    }

    private var optionGrid: some View {
        VStack(spacing: 10) {
            ForEach(options, id: \.id) { option in
                Button {
                    selectedOption = option
                } label: {
                    Text(option.infinitive)
                        .font(.headline)
                        .frame(maxWidth: .infinity)
                        .padding(.vertical, 16)
                }
                .glassEffect(in: RoundedRectangle(cornerRadius: 14))
                .tint(.primary)
            }
        }
    }

    private func revealedContent(_ verb: Verb) -> some View {
        VStack(spacing: 16) {
            answerFeedback(verb)
            VerbIllustration(verb: verb)
            exampleBlock(for: verb)
            ratingButtons
        }
    }

    private func answerFeedback(_ verb: Verb) -> some View {
        let correct = (selectedOption?.id == verb.id)
        return VStack(spacing: 6) {
            Image(systemName: correct ? "checkmark.circle.fill" : "xmark.circle.fill")
                .font(.system(size: 36))
                .foregroundStyle(correct ? .green : .red)
            Text(correct ? "Correct!" : "Not quite")
                .font(.headline)
                .foregroundStyle(correct ? .green : .red)
            Text(verb.infinitive)
                .font(.title2.weight(.semibold))
                .padding(.top, 4)
        }
    }

    @ViewBuilder
    private func exampleBlock(for verb: Verb) -> some View {
        if let example = exampleByVerbId[verb.id] {
            VStack(alignment: .leading, spacing: 4) {
                Text(example.spanish).font(.subheadline).italic()
                Text(example.english).font(.caption).foregroundStyle(.secondary)
            }
            .frame(maxWidth: .infinity, alignment: .leading)
            .padding()
            .background(.fill.quinary, in: RoundedRectangle(cornerRadius: 12))
        } else if generatingExampleForVerbId == verb.id {
            HStack(spacing: 8) {
                ProgressView()
                Text("Generating example…")
                    .font(.caption)
                    .foregroundStyle(.secondary)
            }
            .frame(maxWidth: .infinity)
            .padding()
            .background(.fill.quinary, in: RoundedRectangle(cornerRadius: 12))
        }
    }

    private var ratingButtons: some View {
        VStack(spacing: 10) {
            Text("How well did you know it?")
                .font(.subheadline)
                .foregroundStyle(.secondary)
            HStack(spacing: 10) {
                ratingButton("Again", color: .red, quality: .again)
                ratingButton("Hard", color: .orange, quality: .hard)
                ratingButton("Good", color: .green, quality: .good)
                ratingButton("Easy", color: .blue, quality: .easy)
            }
        }
    }

    private func ratingButton(_ label: String, color: Color, quality: ReviewQuality) -> some View {
        Button {
            rateAndAdvance(quality)
        } label: {
            Text(label)
                .font(.subheadline.weight(.semibold))
                .frame(maxWidth: .infinity)
                .padding(.vertical, 12)
        }
        .tint(color)
        .glassEffect(in: RoundedRectangle(cornerRadius: 12))
    }

    // MARK: - Completion

    private var completionView: some View {
        VStack(spacing: 16) {
            Image(systemName: "checkmark.circle.fill")
                .font(.system(size: 56))
                .foregroundStyle(.green)
            Text("Session Complete")
                .font(.title2.bold())
            Text("\(verbs.count) verbs reviewed")
                .font(.subheadline)
                .foregroundStyle(.secondary)
            Button("Done") { dismiss() }
                .buttonStyle(.borderedProminent)
                .tint(.purple)
                .padding(.top, 12)
        }
        .padding(.top, 60)
    }

    // MARK: - Logic

    private func loadIfNeeded() {
        guard verbs.isEmpty else { return }
        verbs = VocabVerbPool.fetch(localContext: localContext, cloudContext: cloudContext)
        prepareOptions()
        primeExampleForCurrent()
    }

    private func prepareOptions() {
        guard let verb = currentVerb else { options = []; return }
        let candidates = verbs.filter { $0.id != verb.id }
        let distractors = Array(candidates.shuffled().prefix(3))
        options = ([verb] + distractors).shuffled()
    }

    private func primeExampleForCurrent() {
        guard let verb = currentVerb else { return }
        if exampleByVerbId[verb.id] != nil { return }
        if let cached = exampleCache.examples(for: verb.id)?.first {
            exampleByVerbId[verb.id] = cached
            return
        }
        guard VerbExampleGenerator.isAvailable else { return }
        generatingExampleForVerbId = verb.id
        let verbId = verb.id
        let infinitive = verb.infinitive
        let english = verb.english
        Task {
            do {
                let examples = try await VerbExampleGenerator.generate(
                    verbInfinitive: infinitive,
                    verbEnglish: english,
                    tenseIds: ["ind_presente"]
                )
                if let first = examples.first {
                    exampleCache.setExamples(examples, for: verbId)
                    if currentVerb?.id == verbId {
                        exampleByVerbId[verbId] = first
                    }
                }
            } catch {}
            if generatingExampleForVerbId == verbId {
                generatingExampleForVerbId = nil
            }
        }
    }

    private func rateAndAdvance(_ quality: ReviewQuality) {
        guard let verb = currentVerb else { return }
        VerbReviewStore(context: cloudContext).rate(verbId: verb.id, quality: quality)
        index += 1
        selectedOption = nil
        prepareOptions()
        primeExampleForCurrent()
    }
}