import SwiftUI

struct SettingsView: View {
    @Environment(AppState.self) private var appState
    @AppStorage(AppStorageKeys.appTheme, store: .standard) private var appTheme: AppTheme = .system
    @AppStorage(AppStorageKeys.displayDensity, store: .standard) private var displayDensity: DisplayDensity = .standard
    @AppStorage(AppStorageKeys.swipeActionsEnabled, store: .standard) private var swipeActionsEnabled = true
    @AppStorage(AppStorageKeys.contributionGraphsEnabled, store: .standard) private var contributionGraphsEnabled = true
    @State private var pendingDestructiveAction: SettingsDestructiveAction?
    @State private var showAccountSwitcher = false

    var body: some View {
        Form {
            appearanceSection()
            behaviorSection()
            authenticationSection()
        }
        .themedList()
        .navigationTitle("Settings")
        .sheet(isPresented: $showAccountSwitcher) {
            AccountSwitcherView()
        }
        .alert(
            pendingDestructiveAction?.title ?? "",
            isPresented: Binding(
                get: { pendingDestructiveAction != nil },
                set: { isPresented in
                    if !isPresented {
                        pendingDestructiveAction = nil
                    }
                }
            )
        ) {
            Button("Cancel", role: .cancel) {
                /* Dismiss only; destructive action is separate. */
            }
            Button(pendingDestructiveAction?.confirmationLabel ?? "Confirm", role: .destructive) {
                guard let action = pendingDestructiveAction else { return }
                pendingDestructiveAction = nil
                Task {
                    switch action {
                    case .resetAppData:
                        await appState.resetAppData()
                    case .signOut:
                        await appState.signOut()
                    }
                }
            }
        } message: {
            if let pendingDestructiveAction {
                Text(pendingDestructiveAction.message)
            }
        }
    }

    @ViewBuilder
    private func appearanceSection() -> some View {
        Section {
            Picker("Theme", selection: $appTheme) {
                ForEach(AppTheme.allCases) { theme in
                    Text(theme.label).tag(theme)
                }
            }
            .themedRow()
            Picker("Density", selection: $displayDensity) {
                ForEach(DisplayDensity.allCases) { density in
                    Text(density.label).tag(density)
                }
            }
            .themedRow()
        } header: {
            Text("Appearance")
        } footer: {
            Text("Compact density reduces spacing throughout the app.")
        }
    }

    @ViewBuilder
    private func behaviorSection() -> some View {
        Section {
            Toggle("Swipe actions", isOn: $swipeActionsEnabled)
                .themedRow()
            Toggle("Contribution graphs", isOn: $contributionGraphsEnabled)
                .onChange(of: contributionGraphsEnabled) { _, newValue in
                    ContributionWidgetContextStore.setEnabled(newValue)
                }
                .themedRow()
        } header: {
            Text("Behavior")
        } footer: {
            Text("When enabled, swipe list rows to quickly take actions like resolving tickets, cancelling builds, and deleting pastes. Contribution graphs controls whether SourceHut activity heatmaps appear in lookup profiles.")
        }
    }

    @ViewBuilder
    private func authenticationSection() -> some View {
        Section {
            HStack {
                Image(systemName: "key.fill")
                    .foregroundStyle(.secondary)
                VStack(alignment: .leading, spacing: 2) {
                    Text(appState.currentUser?.canonicalName ?? "No active account")
                    Text("\(appState.accounts.count) saved account\(appState.accounts.count == 1 ? "" : "s")")
                        .font(.caption)
                        .foregroundStyle(.secondary)
                }
            }
            .alignmentGuide(.listRowSeparatorLeading) { _ in 0 }
            .themedRow()

            Button {
                showAccountSwitcher = true
            } label: {
                Label("Manage Accounts", systemImage: "person.2")
            }
            .themedRow()

            HStack {
                Image(systemName: "lock.shield")
                    .foregroundStyle(.secondary)
                Text("Tokens are stored separately per account in the iOS keychain")
                    .font(.subheadline)
                    .foregroundStyle(.secondary)
            }
            .alignmentGuide(.listRowSeparatorLeading) { _ in 0 }
            .themedRow()

            Button("Reset App Data", role: .destructive) {
                pendingDestructiveAction = .resetAppData
            }
            .themedRow()

            Button("Sign Out", role: .destructive) {
                pendingDestructiveAction = .signOut
            }
            .themedRow()
        } header: {
            Text("Authentication")
        } footer: {
            Text("Account switching keeps local caches and saved state isolated per account. Sign Out removes all saved accounts from this device. Reset App Data also clears local settings, cached responses, cookies, and embedded web data.")
        }
    }

}

func settingsBioAttributedString(_ markdown: String) -> AttributedString {
    profileBioAttributedString(markdown)
}

private enum SettingsDestructiveAction {
    case resetAppData
    case signOut

    var title: String {
        switch self {
        case .resetAppData:
            "Reset App Data?"
        case .signOut:
            "Sign Out?"
        }
    }

    var confirmationLabel: String {
        switch self {
        case .resetAppData:
            "Reset App Data"
        case .signOut:
            "Sign Out"
        }
    }

    var message: String {
        switch self {
        case .resetAppData:
            "This signs you out and removes saved token data, local settings, cached responses, cookies, and embedded web content on this device."
        case .signOut:
            "This signs you out of Hutch and clears saved authentication state on this device."
        }
    }
}