import SwiftUI

/// Modal sheet for scanning nearby BLE audio recording devices and binding them to the logged-in user.
struct DeviceScanView: View {
    @Environment(\.dismiss) private var dismiss
    @ObservedObject var bleManager: BLEManager = .shared
    @ObservedObject var authManager: AuthManager = .shared
    
    @State private var boundSuccessMessage: String?
    @State private var bindingDeviceID: String?
    @State private var bindingErrorMessage: String?
    
    var body: some View {
        ZStack {
            Color.spaceBlack.ignoresSafeArea()
            
            VStack(spacing: 20) {
                // Top Header
                HStack {
                    VStack(alignment: .leading, spacing: 4) {
                        Text("搜索与绑定录音设备")
                            .font(.system(size: 18, weight: .bold))
                            .foregroundStyle(Color.primary)
                        
                        Text("请确保设备已开启蓝牙广播模式并靠拢 iPhone")
                            .font(.system(size: 12))
                            .foregroundStyle(Color.secondary)
                    }
                    
                    Spacer()
                    
                    Button {
                        bleManager.stopScanning()
                        dismiss()
                    } label: {
                        Image(systemName: "xmark.circle.fill")
                            .font(.system(size: 22))
                            .foregroundStyle(Color.secondary.opacity(0.6))
                    }
                }
                .padding(.horizontal, 20)
                .padding(.top, 20)
                
                // Scanning Status Indicator
                HStack(spacing: 12) {
                    if bleManager.isScanning {
                        ProgressView()
                            .tint(Color.primary)
                    } else {
                        Image(systemName: "radiowaves.left.and.right")
                            .font(.system(size: 16))
                            .foregroundStyle(Color.primary)
                    }
                    
                    Text(bleManager.isScanning ? "正在扫描附近的蓝牙录音设备..." : "扫描已停止")
                        .font(.system(size: 13, weight: .medium))
                        .foregroundStyle(Color.primary)
                    
                    Spacer()
                    
                    Button {
                        if bleManager.isScanning {
                            bleManager.stopScanning()
                        } else {
                            bleManager.startScanning()
                        }
                    } label: {
                        Text(bleManager.isScanning ? "停止扫描" : "重新扫描")
                            .font(.system(size: 12, weight: .regular))
                            .foregroundStyle(Color.primary)
                            .padding(.horizontal, 10)
                            .padding(.vertical, 6)
                            .overlay(
                                RoundedRectangle(cornerRadius: 6)
                                    .stroke(Color.primary.opacity(0.3), lineWidth: 1)
                            )
                    }
                }
                .padding(14)
                .background(Color.cardBackground.opacity(0.4))
                .businessBorder(cornerRadius: 10)
                .padding(.horizontal, 20)
                
                // Success Toast Banner
                if let successMsg = boundSuccessMessage {
                    HStack(spacing: 8) {
                        Image(systemName: "checkmark.circle.fill")
                            .foregroundStyle(Color.primary)
                        Text(successMsg)
                            .font(.system(size: 13, weight: .medium))
                            .foregroundStyle(Color.primary)
                    }
                    .padding(.vertical, 10)
                    .padding(.horizontal, 16)
                    .background(Color.primary.opacity(0.1))
                    .cornerRadius(8)
                    .transition(.move(edge: .top).combined(with: .opacity))
                }
                
                // Discovered Devices List
                if bleManager.discoveredDevices.isEmpty {
                    VStack(spacing: 12) {
                        Spacer()
                        Image(systemName: "antenna.radiowaves.left.and.right")
                            .font(.system(size: 36, weight: .ultraLight))
                            .foregroundStyle(Color.secondary.opacity(0.4))
                        
                        Text("未搜索到可用的蓝牙录音设备")
                            .font(.system(size: 13))
                            .foregroundStyle(Color.secondary)
                        Spacer()
                    }
                } else {
                    ScrollView {
                        VStack(spacing: 12) {
                            ForEach(bleManager.discoveredDevices) { device in
                                discoveredDeviceRow(device)
                            }
                        }
                        .padding(.horizontal, 20)
                        .padding(.bottom, 20)
                    }
                }
            }
        }
        .onAppear {
            bleManager.startScanning()
        }
        .onDisappear {
            bleManager.stopScanning()
        }
        .alert("无法绑定微光", isPresented: Binding(
            get: { bindingErrorMessage != nil },
            set: { if !$0 { bindingErrorMessage = nil } }
        )) {
            Button("知道了", role: .cancel) { bindingErrorMessage = nil }
        } message: {
            Text(bindingErrorMessage ?? "请稍后重试。")
        }
    }
    
    private func discoveredDeviceRow(_ device: DiscoveredBLEDevice) -> some View {
        let isAlreadyBound = bleManager.boundDevices.contains(where: { $0.id == device.id })
        
        return HStack(spacing: 14) {
            ZStack {
                Circle()
                    .fill(Color.primary.opacity(0.06))
                    .frame(width: 42, height: 42)
                
                Image(systemName: "mic.fill")
                    .font(.system(size: 16))
                    .foregroundStyle(Color.primary)
            }
            
            VStack(alignment: .leading, spacing: 4) {
                Text("微光(Spark)")
                    .font(.system(size: 14, weight: .medium))
                    .foregroundStyle(Color.primary)
                
                HStack(spacing: 8) {
                    Text("信号强度: \(device.rssi) dBm")
                        .font(.system(size: 11, design: .monospaced))
                        .foregroundStyle(Color.secondary)
                    
                    Text("•")
                        .font(.system(size: 10))
                        .foregroundStyle(Color.secondary)
                    
                    Text("设备标识: " + String(device.peripheralUUID.prefix(8)))
                        .font(.system(size: 11, design: .monospaced))
                        .foregroundStyle(Color.secondary)
                }

                Text("广播名称: \(device.name)")
                    .font(.system(size: 10))
                    .foregroundStyle(Color.secondary.opacity(0.8))
            }
            
            Spacer()
            
            if isAlreadyBound {
                Text("已绑定")
                    .font(.system(size: 12, weight: .regular))
                    .foregroundStyle(Color.secondary)
                    .padding(.horizontal, 12)
                    .padding(.vertical, 6)
            } else {
                Button {
                    guard let userId = authManager.currentUser?.id else { return }
                    bindingDeviceID = device.id
                    bleManager.connectAndBind(device, userId: userId) { result in
                        bindingDeviceID = nil
                        switch result {
                        case .success(let bound):
                            withAnimation {
                                boundSuccessMessage = "已成功绑定设备「\(bound.name)」"
                            }
                            DispatchQueue.main.asyncAfter(deadline: .now() + 1.2) {
                                dismiss()
                            }
                        case .failure(let error):
                            bindingErrorMessage = error.localizedDescription
                        }
                    }
                } label: {
                    Group {
                        if bindingDeviceID == device.id {
                            ProgressView()
                                .tint(Color.spaceBlack)
                        } else {
                            Text("绑定设备")
                                .font(.system(size: 13, weight: .semibold))
                        }
                    }
                    .foregroundStyle(Color.spaceBlack)
                    .frame(minWidth: 72)
                    .padding(.horizontal, 14)
                    .padding(.vertical, 7)
                    .background(Color.primary)
                    .cornerRadius(6)
                }
                .disabled(bindingDeviceID != nil)
            }
        }
        .padding(14)
        .background(Color.cardBackground.opacity(0.3))
        .businessBorder(cornerRadius: 10)
    }
}

#Preview {
    DeviceScanView()
}