import SwiftUI

struct SidebarView: View {
    @Environment(\.requirePremiumAccess) private var requirePremiumAccess
    @EnvironmentObject private var subscriptions: SubscriptionManager
    @ObservedObject private var paywallConfigService = PaywallConfigService.shared
    @Bindable var viewModel: FrontPageViewModel
    var isPremium: Bool

    private var sidebarConfig: PaywallConfig.Sidebar {
        paywallConfigService.config.sidebar
    }

    var body: some View {
        VStack(spacing: 0) {
            header
            navigationSections
            Spacer(minLength: 0)
            upgradeCard
        }
        .frame(width: AppTheme.sidebarWidth)
        .frame(maxHeight: .infinity, alignment: .top)
        .background(AppTheme.sidebarBackground)
    }

    private var header: some View {
        HStack(spacing: AppTheme.sidebarRowSpacing) {
            Image("AppLogo")
                .resizable()
                .interpolation(.high)
                .scaledToFit()
                .frame(width: AppTheme.iconContainerSize, height: AppTheme.iconContainerSize)

            VStack(alignment: .leading, spacing: 2) {
                Text("Reddora AI")
                    .font(.system(size: 15, weight: .bold))
                    .foregroundStyle(AppTheme.textPrimary)
                Text("AI Assistant for Reddit")
                    .font(.system(size: 10))
                    .foregroundStyle(AppTheme.textSecondary)
            }

            Spacer(minLength: 0)
        }
        .padding(.horizontal, AppTheme.sidebarContentInset + AppTheme.sidebarRowPaddingH)
        .padding(.top, 20)
        .padding(.bottom, 16)
    }

    private var navigationSections: some View {
        ScrollView {
            VStack(alignment: .leading, spacing: AppTheme.sidebarSectionSpacing) {
                sidebarSection(title: SidebarSection.quickAccess.rawValue) {
                    SidebarQuickAccessItemView(isSelected: viewModel.isRedditActive) {
                        guard requirePremiumAccess() else { return }
                        viewModel.openReddit()
                    }
                }

                sidebarSection(title: SidebarSection.create.rawValue) {
                    ForEach(viewModel.createItems) { item in
                        SidebarNavItemView(
                            item: item,
                            isSelected: !viewModel.isSettingsActive && !viewModel.isHistoryActive && !viewModel.isRedditActive && viewModel.selectedNavItem == item
                        ) {
                            viewModel.selectNavItem(item)
                        }
                    }
                }

                sidebarSection(title: SidebarSection.history.rawValue) {
                    SidebarNavItemView(
                        item: FrontPageViewModel.historyItem,
                        isSelected: viewModel.isHistoryActive
                    ) {
                        viewModel.openHistory()
                    }
                }

                sidebarSection(title: SidebarSection.settings.rawValue) {
                    SidebarNavItemView(
                        item: FrontPageViewModel.settingsItem,
                        isSelected: viewModel.isSettingsActive
                    ) {
                        viewModel.openSettings()
                    }
                }
            }
            .padding(.horizontal, AppTheme.sidebarContentInset)
            .padding(.top, 4)
        }
    }

    private func sidebarSection<Content: View>(
        title: String,
        @ViewBuilder content: () -> Content
    ) -> some View {
        VStack(alignment: .leading, spacing: AppTheme.sidebarItemSpacing) {
            SidebarSectionHeader(title: title)
            content()
        }
    }

    private var upgradeCard: some View {
        VStack(spacing: 0) {
            Rectangle()
                .fill(AppTheme.border)
                .frame(height: 1)

            VStack(alignment: .center, spacing: 8) {
                VStack(spacing: 4) {
                    Image(systemName: "crown.fill")
                        .font(.system(size: 14))
                        .foregroundStyle(AppTheme.accentYellow)
                    Text(isPremium ? sidebarConfig.proTitle : sidebarConfig.unlockTitle)
                        .font(.system(size: 12, weight: .semibold))
                        .foregroundStyle(AppTheme.textPrimary)
                }
                .frame(maxWidth: .infinity, alignment: .center)

                Text(isPremium ? sidebarConfig.proDescription : sidebarConfig.unlockDescription)
                    .font(.system(size: 10))
                    .foregroundStyle(AppTheme.textSecondary)
                    .multilineTextAlignment(.center)
                    .frame(maxWidth: .infinity, alignment: .center)
                    .fixedSize(horizontal: false, vertical: true)
                    .lineSpacing(2)

                Button(premiumActionTitle) {
                    if isPremium {
                        if subscriptions.hasActiveSubscription {
                            subscriptions.openSubscriptionManagement()
                        } else {
                            viewModel.showPaywall()
                        }
                    } else {
                        viewModel.showPaywall()
                    }
                }
                    .font(.system(size: 11, weight: .semibold))
                    .foregroundStyle(.white)
                    .frame(maxWidth: .infinity)
                    .padding(.vertical, 7.5)
                    .background(AppTheme.accentPurple)
                    .clipShape(RoundedRectangle(cornerRadius: 8))
                    .buttonStyle(AppPrimaryButtonStyle())
            }
            .frame(maxWidth: .infinity, minHeight: 105)
            .padding(.horizontal, 12)
            .padding(.vertical, 12)
            .background(
                RoundedRectangle(cornerRadius: AppTheme.cornerRadiusSmall)
                    .fill(AppTheme.cardBackground)
                    .overlay(
                        RoundedRectangle(cornerRadius: AppTheme.cornerRadiusSmall)
                            .stroke(AppTheme.accentPurple.opacity(0.25), lineWidth: 1)
                    )
            )
            .padding(.horizontal, AppTheme.sidebarContentInset + 8)
            .padding(.top, 12)
            .padding(.bottom, 20)
        }
    }

    private var premiumActionTitle: String {
        if isPremium {
            return subscriptions.hasLifetimeAccess
                ? sidebarConfig.lifetimeAction
                : sidebarConfig.manageSubscriptionAction
        }
        return sidebarConfig.upgradeAction
    }
}