import SwiftUI

private let loginAccent = AppTheme.accent

struct LoginRootView: View {
    @ObservedObject var model: AppViewModel
    @Environment(\.horizontalSizeClass) private var horizontalSizeClass

    var body: some View {
        AppScrollScreen(compactLayout: compactLayout) {
            LoginHeroPanel(model: model, compactLayout: compactLayout)
            PairingConsoleCard(model: model, compactLayout: compactLayout)
        }
        .sheet(isPresented: $model.isScannerPresented) {
            QRScannerSheet(
                seededPayload: model.suggestedPairingPayload,
                title: "Scan linking QR",
                description: "Use the camera to scan the QR code from the web flow that activates this device as your passport.",
                navigationTitle: "Scan Linking QR",
                onCodeScanned: { payload in
                    model.manualPairingPayload = payload
                    Task {
                        await model.signIn(with: payload, transport: .qr)
                    }
                }
            )
        }
    }

    private var compactLayout: Bool {
        #if os(iOS)
        horizontalSizeClass == .compact
        #else
        false
        #endif
    }
}

private struct LoginHeroPanel: View {
    @ObservedObject var model: AppViewModel
    let compactLayout: Bool

    var body: some View {
        AppPanel(compactLayout: compactLayout, radius: AppLayout.largeCardRadius) {
            AppBadge(title: "Secure passport setup", tone: loginAccent)

            Text("Turn this device into a passport for your idp.global identity")
                .font(.system(size: compactLayout ? 28 : 36, weight: .bold, design: .rounded))
                .lineLimit(3)

            Text("Scan a linking QR code or paste a payload to activate this device as your passport for identity proofs and security alerts.")
                .font(.subheadline)
                .foregroundStyle(.secondary)

            Divider()

            VStack(alignment: .leading, spacing: 14) {
                LoginFeatureRow(icon: "qrcode.viewfinder", title: "Scan a QR code from the web flow")
                LoginFeatureRow(icon: "doc.text.viewfinder", title: "Paste a payload when you already have one")
                LoginFeatureRow(icon: "iphone.gen3", title: "Handle identity checks and alerts here")
            }

            if model.isBootstrapping {
                ProgressView("Preparing preview passport...")
                    .tint(loginAccent)
            }
        }
    }
}

private struct LoginFeatureRow: View {
    let icon: String
    let title: String

    var body: some View {
        HStack(alignment: .center, spacing: 12) {
            Image(systemName: icon)
                .font(.subheadline.weight(.semibold))
                .foregroundStyle(loginAccent)
                .frame(width: 28, height: 28)

            Text(title)
                .font(.headline)

            Spacer(minLength: 0)
        }
    }
}

private struct PairingConsoleCard: View {
    @ObservedObject var model: AppViewModel
    let compactLayout: Bool

    var body: some View {
        AppSectionCard(title: "Set up passport", compactLayout: compactLayout) {
            VStack(alignment: .leading, spacing: 8) {
                Text("Link payload")
                    .font(.subheadline.weight(.semibold))

                AppTextEditorField(
                    text: $model.manualPairingPayload,
                    minHeight: compactLayout ? 132 : 150
                )
            }

            if model.isAuthenticating {
                HStack(spacing: 10) {
                    ProgressView()
                    Text("Activating this passport...")
                        .foregroundStyle(.secondary)
                }
            }

            Text("NFC, QR, and OTP proof methods become available after this passport is active.")
                .font(.footnote)
                .foregroundStyle(.secondary)

            if compactLayout {
                VStack(spacing: 12) {
                    primaryButtons
                    secondaryButtons
                }
            } else {
                VStack(spacing: 12) {
                    HStack(spacing: 12) {
                        primaryButtons
                    }

                    secondaryButtons
                }
            }
        }
    }

    @ViewBuilder
    private var primaryButtons: some View {
        Button {
            model.isScannerPresented = true
        } label: {
            Label("Scan QR", systemImage: "qrcode.viewfinder")
                .frame(maxWidth: .infinity)
        }
        .buttonStyle(.borderedProminent)
        .controlSize(.large)
    }

    @ViewBuilder
    private var secondaryButtons: some View {
        if compactLayout {
            VStack(spacing: 12) {
                usePayloadButton
                previewPayloadButton
            }
        } else {
            HStack(spacing: 12) {
                usePayloadButton
                previewPayloadButton
            }
        }
    }

    private var usePayloadButton: some View {
        Button {
            Task {
                await model.signInWithManualPayload()
            }
        } label: {
            if model.isAuthenticating {
                ProgressView()
                    .frame(maxWidth: .infinity)
            } else {
                Label("Link with payload", systemImage: "arrow.right.circle")
                    .frame(maxWidth: .infinity)
            }
        }
        .buttonStyle(.bordered)
        .controlSize(.large)
        .disabled(model.isAuthenticating)
    }

    private var previewPayloadButton: some View {
        Button {
            Task {
                await model.signInWithSuggestedPayload()
            }
        } label: {
            Label("Use preview passport", systemImage: "wand.and.stars")
                .frame(maxWidth: .infinity)
        }
        .buttonStyle(.bordered)
        .controlSize(.large)
    }
}