import SwiftUI

struct TitleOptimizerView: View {
    @Environment(\.requirePremiumAccess) private var requirePremiumAccess
    @Bindable var viewModel: TitleOptimizerViewModel

    var body: some View {
        VStack(spacing: 0) {
            header
            tabBar

            ScrollView {
                PostPageBoundary {
                    switch viewModel.selectedTab {
                    case .optimize:
                        optimizeContent
                    case .compare:
                        compareContent
                    case .preview:
                        previewContent
                    }
                }
                .padding(.horizontal, 24)
                .padding(.top, 8)
                .padding(.bottom, 24)
            }
        }
        .background(AppTheme.background)
    }

    // MARK: - Header

    private var header: some View {
        HStack(spacing: 14) {
            ModernSidebarIconView(kind: .titleOptimizer, size: 40)

            VStack(alignment: .leading, spacing: 2) {
                Text("Title Optimizer")
                    .font(.system(size: 18, weight: .semibold))
                    .foregroundStyle(AppTheme.textPrimary)
                Text("Craft viral Reddit titles with AI")
                    .font(.system(size: 11))
                    .foregroundStyle(AppTheme.textSecondary)
            }

            Spacer()

            headerActions
        }
        .padding(.horizontal, 24)
        .padding(.vertical, 16)
        .overlay(alignment: .bottom) {
            Rectangle()
                .fill(AppTheme.border)
                .frame(height: 1)
        }
    }

    private var headerActions: some View {
        HStack(spacing: 8) {
            Button {
                viewModel.resetDraft()
            } label: {
                Label("Reset", systemImage: "arrow.counterclockwise")
                    .font(.system(size: 11, weight: .medium))
            }
            .buttonStyle(TitleSecondaryButtonStyle())

            Button {
                viewModel.copyToClipboard()
            } label: {
                Label("Copy", systemImage: "doc.on.doc")
                    .font(.system(size: 11, weight: .medium))
            }
            .buttonStyle(TitleSecondaryButtonStyle())
            .disabled(viewModel.activeTitle.trimmingCharacters(in: .whitespaces).isEmpty)

            Button {
                guard requirePremiumAccess() else { return }
                Task { await viewModel.optimizeTitles() }
            } label: {
                HStack(spacing: 6) {
                    if viewModel.isOptimizing {
                        ProgressView()
                            .controlSize(.small)
                            .tint(.white)
                    } else {
                        Image(systemName: "sparkles")
                            .font(.system(size: 11, weight: .semibold))
                    }
                    Text(viewModel.isOptimizing ? "Optimizing…" : "Optimize")
                        .font(.system(size: 11, weight: .semibold))
                }
                .foregroundStyle(.white)
                .padding(.horizontal, 14)
                .padding(.vertical, 8)
                .background(viewModel.canOptimize ? AppTheme.accentBlue : AppTheme.accentBlue.opacity(0.4))
                .clipShape(RoundedRectangle(cornerRadius: 8))
            }
            .buttonStyle(.plain)
            .disabled(!viewModel.canOptimize)
        }
    }

    // MARK: - Tab Bar

    private var tabBar: some View {
        HStack(spacing: 4) {
            ForEach(TitleOptimizerTab.allCases) { tab in
                Button {
                    viewModel.selectedTab = tab
                } label: {
                    Text(tab.title)
                        .font(.system(size: 11, weight: .semibold))
                        .foregroundStyle(viewModel.selectedTab == tab ? AppTheme.textPrimary : AppTheme.textSecondary)
                        .padding(.horizontal, 14)
                        .padding(.vertical, 8)
                        .background(
                            viewModel.selectedTab == tab
                                ? AppTheme.cardBackground
                                : Color.clear
                        )
                        .clipShape(RoundedRectangle(cornerRadius: 8))
                }
                .buttonStyle(.plain)
            }

            Spacer()
        }
        .padding(.horizontal, 24)
        .padding(.top, 12)
        .padding(.bottom, 4)
    }

    // MARK: - Optimize

    private var optimizeContent: some View {
        HStack(alignment: .top, spacing: 16) {
            configurationPanel
            editorPanel
        }
    }

    private var configurationPanel: some View {
        VStack(spacing: 12) {
            PostFormCard(title: "Target Subreddit", subtitle: "Tailor titles for the community") {
                PostFormField(
                    label: "Subreddit",
                    placeholder: "technology",
                    text: $viewModel.draft.subreddit,
                    prefix: "r/"
                )
            }

            PostFormCard(title: "AI Settings", subtitle: "Guide topic, tone, and style") {
                VStack(alignment: .leading, spacing: 12) {
                    PostFormField(
                        label: "Topic / Keywords",
                        placeholder: "e.g. macOS productivity tips",
                        text: $viewModel.draft.topic
                    )

                    VStack(alignment: .leading, spacing: 6) {
                        Text("Tone")
                            .font(.system(size: 10, weight: .medium))
                            .foregroundStyle(AppTheme.textTertiary)
                        TonePicker(selectedTone: $viewModel.draft.tone)
                    }
                }
            }

            PostFormCard(title: "Title Goal", subtitle: "What kind of hook do you want?") {
                TitleGoalPicker(selectedGoal: $viewModel.draft.titleGoal)
            }

            PostFormCard(title: "Post Context", subtitle: "Optional — affects preview style") {
                VStack(alignment: .leading, spacing: 12) {
                    PostTypePicker(selectedType: Binding(
                        get: { viewModel.draft.postType },
                        set: { viewModel.selectPostType($0) }
                    ))

                    PostFormField(
                        label: "Flair",
                        placeholder: "Discussion, Question, Meme…",
                        text: $viewModel.draft.flair
                    )
                }
            }

            PostFormCard(title: "Post Tags", subtitle: "Reddit content labels") {
                HStack(spacing: 6) {
                    PostTagToggle(
                        title: "NSFW",
                        systemImage: "exclamationmark.triangle.fill",
                        activeColor: Color(hex: 0xEF4444),
                        isOn: $viewModel.draft.isNSFW
                    )
                    PostTagToggle(
                        title: "Spoiler",
                        systemImage: "eye.slash.fill",
                        activeColor: AppTheme.textSecondary,
                        isOn: $viewModel.draft.isSpoiler
                    )
                    PostTagToggle(
                        title: "OC",
                        systemImage: "star.fill",
                        activeColor: AppTheme.accentGreen,
                        isOn: $viewModel.draft.isOC
                    )
                }
            }

            PostFormCard(title: "Suggestions", subtitle: "How many variants to generate") {
                TitleVariantCountPicker(selectedCount: $viewModel.draft.variantCount)
            }

            if let error = viewModel.errorMessage {
                PostGeneratorMessageBanner(message: error, isError: true)
            } else if let success = viewModel.successMessage {
                PostGeneratorMessageBanner(message: success, isError: false)
            }
        }
        .frame(width: 300)
    }

    private var editorPanel: some View {
        VStack(spacing: 12) {
            PostFormCard(title: "Original Title", subtitle: "The title you want to improve") {
                PostFormField(
                    label: "Post Title",
                    placeholder: "Enter your draft title here",
                    text: $viewModel.draft.originalTitle
                )
            }

            characterCountFooter

            if let analysis = viewModel.analysis {
                TitleAnalysisCard(analysis: analysis)
            }

            suggestionsSection
        }
        .frame(maxWidth: .infinity)
    }

    @ViewBuilder
    private var suggestionsSection: some View {
        PostFormCard(
            title: "AI Suggestions",
            subtitle: viewModel.variants.isEmpty
                ? "Hit Optimize to generate title variants"
                : "\(viewModel.variants.count) optimized titles ranked by score"
        ) {
            if viewModel.variants.isEmpty {
                TitleOptimizerEmptyState(
                    icon: "textformat.size",
                    title: "No suggestions yet",
                    subtitle: "Fill in your subreddit, topic, and title,\nthen tap Optimize to get AI-powered variants."
                )
            } else {
                VStack(spacing: 8) {
                    ForEach(viewModel.variants) { variant in
                        TitleVariantRow(
                            variant: variant,
                            isSelected: viewModel.selectedVariantID == variant.id,
                            onSelect: { viewModel.selectVariant(variant) },
                            onApply: { viewModel.applyVariant(variant) }
                        )
                    }
                }
            }
        }
    }

    private var characterCountFooter: some View {
        HStack {
            Text("\(viewModel.draft.originalTitle.count) / 300")
                .font(.system(size: 10))
                .foregroundStyle(
                    viewModel.draft.originalTitle.count > 300 ? Color(hex: 0xF87171) : AppTheme.textTertiary
                )

            Spacer()

            Text("Reddit limit: 300 characters for title")
                .font(.system(size: 10))
                .foregroundStyle(AppTheme.textTertiary)
        }
    }

    // MARK: - Compare

    private var compareContent: some View {
        VStack(spacing: 16) {
            if viewModel.variants.isEmpty {
                TitleOptimizerEmptyState(
                    icon: "arrow.left.arrow.right",
                    title: "Nothing to compare yet",
                    subtitle: "Generate title suggestions on the Optimize tab first."
                )
            } else {
                compareHeader

                TitleCompareCard(
                    title: viewModel.draft.originalTitle,
                    score: viewModel.analysis?.overallScore,
                    label: "Original",
                    isOriginal: true,
                    isSelected: viewModel.selectedVariantID == nil
                )

                HStack {
                    Rectangle()
                        .fill(AppTheme.border)
                        .frame(height: 1)
                    Text("vs")
                        .font(.system(size: 10, weight: .semibold))
                        .foregroundStyle(AppTheme.textTertiary)
                        .padding(.horizontal, 8)
                    Rectangle()
                        .fill(AppTheme.border)
                        .frame(height: 1)
                }

                VStack(spacing: 8) {
                    ForEach(viewModel.variants) { variant in
                        TitleCompareCard(
                            title: variant.title,
                            score: variant.score,
                            label: "Variant #\(variantRank(variant))",
                            isOriginal: false,
                            isSelected: viewModel.selectedVariantID == variant.id
                        )
                        .onTapGesture {
                            viewModel.selectVariant(variant)
                        }
                    }
                }

                compareMetadata
            }
        }
        .frame(maxWidth: 640)
        .frame(maxWidth: .infinity)
    }

    private var compareHeader: some View {
        HStack {
            VStack(alignment: .leading, spacing: 2) {
                Text("Side-by-Side Comparison")
                    .font(.system(size: 12, weight: .semibold))
                    .foregroundStyle(AppTheme.textPrimary)
                Text("Tap a variant to select it as active")
                    .font(.system(size: 10))
                    .foregroundStyle(AppTheme.textSecondary)
            }

            Spacer()

            if let best = viewModel.bestVariant {
                HStack(spacing: 6) {
                    Image(systemName: "trophy.fill")
                        .font(.system(size: 10))
                        .foregroundStyle(AppTheme.accentYellow)
                    Text("Best: \(best.score)/100")
                        .font(.system(size: 10, weight: .semibold))
                        .foregroundStyle(AppTheme.textSecondary)
                }
            }
        }
    }

    private var compareMetadata: some View {
        VStack(alignment: .leading, spacing: 8) {
            metadataRow(label: "Subreddit", value: viewModel.formattedSubreddit)
            metadataRow(label: "Goal", value: viewModel.draft.titleGoal.title)
            metadataRow(label: "Tone", value: viewModel.draft.tone.title)
            metadataRow(label: "Active", value: viewModel.activeTitle)
        }
        .padding(14)
        .frame(maxWidth: .infinity, alignment: .leading)
        .background(
            RoundedRectangle(cornerRadius: AppTheme.cornerRadiusSmall)
                .fill(AppTheme.cardBackground)
                .overlay(
                    RoundedRectangle(cornerRadius: AppTheme.cornerRadiusSmall)
                        .stroke(AppTheme.cardBorder, lineWidth: 1)
                )
        )
    }

    private func variantRank(_ variant: TitleVariant) -> Int {
        (viewModel.variants.firstIndex(where: { $0.id == variant.id }) ?? 0) + 1
    }

    // MARK: - Preview

    private var previewContent: some View {
        VStack(spacing: 16) {
            Text("Live Preview")
                .font(.system(size: 12, weight: .semibold))
                .foregroundStyle(AppTheme.textSecondary)
                .frame(maxWidth: .infinity, alignment: .leading)

            RedditPostPreviewCard(
                draft: viewModel.previewDraft,
                formattedSubreddit: viewModel.formattedSubreddit
            )

            PostFormCard(title: "Feed Preview", subtitle: "How your title looks in a crowded feed") {
                VStack(spacing: 6) {
                    TitleFeedPreviewRow(
                        title: "Other trending post in this subreddit right now",
                        subreddit: viewModel.formattedSubreddit
                    )
                    TitleFeedPreviewRow(
                        title: viewModel.activeTitle,
                        subreddit: viewModel.formattedSubreddit,
                        isHighlighted: true
                    )
                    TitleFeedPreviewRow(
                        title: "Another popular discussion happening nearby",
                        subreddit: viewModel.formattedSubreddit
                    )
                }
            }

            previewMetadata
        }
        .frame(maxWidth: 560)
        .frame(maxWidth: .infinity)
    }

    private var previewMetadata: some View {
        VStack(alignment: .leading, spacing: 8) {
            metadataRow(label: "Active Title", value: viewModel.activeTitle)
            metadataRow(label: "Subreddit", value: viewModel.formattedSubreddit)
            metadataRow(label: "Goal", value: viewModel.draft.titleGoal.title)
            metadataRow(label: "Tone", value: viewModel.draft.tone.title)
            metadataRow(label: "Type", value: viewModel.draft.postType.title)

            if let score = viewModel.analysis?.overallScore {
                metadataRow(label: "Score", value: "\(score)/100")
            }

            if viewModel.draft.isNSFW || viewModel.draft.isSpoiler || viewModel.draft.isOC {
                metadataRow(
                    label: "Tags",
                    value: [
                        viewModel.draft.isNSFW ? "NSFW" : nil,
                        viewModel.draft.isSpoiler ? "Spoiler" : nil,
                        viewModel.draft.isOC ? "OC" : nil,
                    ]
                    .compactMap { $0 }
                    .joined(separator: ", ")
                )
            }
        }
        .padding(14)
        .frame(maxWidth: .infinity, alignment: .leading)
        .background(
            RoundedRectangle(cornerRadius: AppTheme.cornerRadiusSmall)
                .fill(AppTheme.cardBackground)
                .overlay(
                    RoundedRectangle(cornerRadius: AppTheme.cornerRadiusSmall)
                        .stroke(AppTheme.cardBorder, lineWidth: 1)
                )
        )
    }

    private func metadataRow(label: String, value: String) -> some View {
        HStack(alignment: .top) {
            Text(label)
                .font(.system(size: 10, weight: .medium))
                .foregroundStyle(AppTheme.textTertiary)
                .frame(width: 80, alignment: .leading)
            Text(value)
                .font(.system(size: 10))
                .foregroundStyle(AppTheme.textSecondary)
                .fixedSize(horizontal: false, vertical: true)
        }
    }
}

private struct TitleSecondaryButtonStyle: ButtonStyle {
    func makeBody(configuration: Configuration) -> some View {
        configuration.label
            .foregroundStyle(AppTheme.textSecondary)
            .padding(.horizontal, 12)
            .padding(.vertical, 8)
            .background(AppTheme.cardBackground.opacity(configuration.isPressed ? 0.6 : 1))
            .clipShape(RoundedRectangle(cornerRadius: 8))
            .overlay(
                RoundedRectangle(cornerRadius: 8)
                    .stroke(AppTheme.cardBorder, lineWidth: 1)
            )
    }
}

#Preview {
    TitleOptimizerView(viewModel: TitleOptimizerViewModel())
        .frame(width: 880, height: 720)
}