import SwiftUI

// MARK: - SettingsView

/// A compact settings hub. Detailed controls live behind a single function list.
struct SettingsView: View {
    @ObservedObject private var authManager: AuthManager = .shared
    @State private var usedStorageBytes: Int64 = 0
    @State private var availableStorageBytes: Int64 = 0
    @AppStorage(DeveloperLogStore.enabledKey) private var isDeveloperModeEnabled = false

    var body: some View {
        NavigationStack {
            List {
                NavigationLink {
                    ProfileView()
                } label: {
                    settingsRow(
                        icon: "person.crop.circle",
                        title: "账号",
                        detail: accountSummary
                    )
                }

                NavigationLink {
                    RecordingDevicesSettingsView()
                } label: {
                    settingsRow(
                        icon: "mic",
                        title: "我的录音设备"
                    )
                }

                NavigationLink {
                    StorageSettingsView(
                        usedStorageBytes: $usedStorageBytes,
                        availableStorageBytes: $availableStorageBytes,
                        reloadStorageMetrics: reloadStorageMetrics
                    )
                } label: {
                    settingsRow(
                        icon: "internaldrive",
                        title: "存储空间",
                        detail: formattedBytes(usedStorageBytes)
                    )
                }

                NavigationLink {
                    AboutSettingsView()
                } label: {
                    settingsRow(
                        icon: "info.circle",
                        title: "关于",
                        detail: appVersion
                    )
                }

                Section {
                    Toggle(isOn: $isDeveloperModeEnabled) {
                        settingsRow(
                            icon: "hammer",
                            title: "开发者模式"
                        )
                    }
                    .tint(.celestiaCyan)
                }
            }
            .scrollContentBackground(.hidden)
            .background(Color.spaceBlack)
            .listStyle(.insetGrouped)
            .navigationTitle("设置")
            .navigationBarTitleDisplayMode(.inline)
            .task {
                reloadStorageMetrics()
            }
        }
    }

    private var accountSummary: String {
        authManager.currentUser?.username ?? "未登录"
    }

    private var appVersion: String {
        Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as? String ?? "1.0.0"
    }

    private func settingsRow(icon: String, title: String, detail: String? = nil) -> some View {
        HStack(spacing: 14) {
            Image(systemName: icon)
                .font(.system(size: 17, weight: .regular))
                .foregroundStyle(Color.celestiaCyan)
                .frame(width: 24)

            Text(title)
                .foregroundStyle(Color.primary)

            Spacer()

            if let detail {
                Text(detail)
                    .font(.system(size: 13))
                    .foregroundStyle(Color.secondary)
                    .lineLimit(1)
            }
        }
        .padding(.vertical, 5)
    }

    private func formattedBytes(_ bytes: Int64) -> String {
        ByteCountFormatter.string(fromByteCount: bytes, countStyle: .file)
    }

    private func reloadStorageMetrics() {
        let fileManager = FileManager.default
        let roots = [
            fileManager.urls(for: .documentDirectory, in: .userDomainMask).first,
            fileManager.urls(for: .applicationSupportDirectory, in: .userDomainMask).first
        ].compactMap { $0 }

        usedStorageBytes = roots.reduce(0) { total, root in
            let keys: Set<URLResourceKey> = [.isRegularFileKey, .fileSizeKey]
            guard let enumerator = fileManager.enumerator(
                at: root,
                includingPropertiesForKeys: Array(keys)
            ) else {
                return total
            }

            var subtotal: Int64 = 0
            for case let url as URL in enumerator {
                guard let values = try? url.resourceValues(forKeys: keys),
                      values.isRegularFile == true else {
                    continue
                }
                subtotal += Int64(values.fileSize ?? 0)
            }
            return total + subtotal
        }

        let documents = fileManager.urls(for: .documentDirectory, in: .userDomainMask).first
        availableStorageBytes = Int64(
            (try? documents?.resourceValues(
                forKeys: [.volumeAvailableCapacityForImportantUsageKey]
            ).volumeAvailableCapacityForImportantUsage) ?? 0
        )
    }
}

// MARK: - Storage

private struct StorageSettingsView: View {
    @Binding var usedStorageBytes: Int64
    @Binding var availableStorageBytes: Int64
    let reloadStorageMetrics: () -> Void

    @State private var showClearCacheAlert = false

    var body: some View {
        List {
            Section {
                metricRow(label: "App 数据", value: formattedBytes(usedStorageBytes))
                metricRow(label: "设备可用", value: formattedBytes(availableStorageBytes))
            }

            Section {
                Button("清理缓存", role: .destructive) {
                    showClearCacheAlert = true
                }
            } footer: {
                Text("只清除系统缓存目录，不会删除录音、照片或会话记录。")
            }
        }
        .scrollContentBackground(.hidden)
        .background(Color.spaceBlack)
        .navigationTitle("存储空间")
        .navigationBarTitleDisplayMode(.inline)
        .alert("清理缓存", isPresented: $showClearCacheAlert) {
            Button("取消", role: .cancel) {}
            Button("清理", role: .destructive) {
                clearTemporaryCache()
                HapticManager.trigger(.tapFeedback)
            }
        } message: {
            Text("只清除系统缓存目录，不会删除录音、照片或会话记录。")
        }
    }

    private func metricRow(label: String, value: String) -> some View {
        HStack {
            Text(label)
            Spacer()
            Text(value)
                .foregroundStyle(Color.secondary)
        }
    }

    private func formattedBytes(_ bytes: Int64) -> String {
        ByteCountFormatter.string(fromByteCount: bytes, countStyle: .file)
    }

    private func clearTemporaryCache() {
        let fileManager = FileManager.default
        guard let cacheURL = fileManager.urls(for: .cachesDirectory, in: .userDomainMask).first,
              let children = try? fileManager.contentsOfDirectory(
                at: cacheURL,
                includingPropertiesForKeys: nil
              ) else {
            return
        }

        for child in children {
            try? fileManager.removeItem(at: child)
        }
        reloadStorageMetrics()
    }
}

// MARK: - Recording Devices

private struct RecordingDevicesSettingsView: View {
    @ObservedObject private var authManager: AuthManager = .shared
    @ObservedObject private var bleManager: BLEManager = .shared
    @State private var showAuthModal = false
    @State private var showScanDeviceModal = false

    var body: some View {
        ScrollView {
            DeviceListView(
                bleManager: bleManager,
                authManager: authManager,
                onAddDeviceClicked: handleAddDevice
            )
            .padding(16)
        }
        .background(Color.spaceBlack)
        .navigationTitle("我的录音设备")
        .navigationBarTitleDisplayMode(.inline)
        .sheet(isPresented: $showAuthModal) {
            AuthModalView(authManager: authManager)
        }
        .sheet(isPresented: $showScanDeviceModal) {
            DeviceScanView(bleManager: bleManager, authManager: authManager)
        }
    }

    private func handleAddDevice() {
        if authManager.isLoggedIn {
            showScanDeviceModal = true
        } else {
            showAuthModal = true
        }
    }
}

// MARK: - About

private struct AboutSettingsView: View {
    var body: some View {
        List {
            Section {
                infoRow(label: "应用名称", value: "星痕 CelestiaTrace")
                infoRow(label: "版本信息", value: appVersion)
                infoRow(label: "系统支持", value: "iOS 17.0+")
            }

            Section {
                guidanceRow(
                    title: "自动锁定",
                    detail: "系统设置 → 显示与亮度 → 自动锁定"
                )
                guidanceRow(
                    title: "定位权限",
                    detail: "系统设置 → 隐私与安全性 → 定位服务"
                )
            } header: {
                Text("后台运行保障")
            } footer: {
                Text("长时间现场记录前，请确认系统权限与电量充足。")
            }
        }
        .scrollContentBackground(.hidden)
        .background(Color.spaceBlack)
        .navigationTitle("关于")
        .navigationBarTitleDisplayMode(.inline)
    }

    private var appVersion: String {
        Bundle.main.object(forInfoDictionaryKey: "CFBundleShortVersionString") as? String ?? "1.0.0"
    }

    private func infoRow(label: String, value: String) -> some View {
        HStack {
            Text(label)
            Spacer()
            Text(value)
                .foregroundStyle(Color.secondary)
        }
    }

    private func guidanceRow(title: String, detail: String) -> some View {
        VStack(alignment: .leading, spacing: 5) {
            Text(title)
            Text(detail)
                .font(.system(size: 12))
                .foregroundStyle(Color.secondary)
        }
        .padding(.vertical, 3)
    }
}

// MARK: - Preview

#Preview {
    SettingsView()
}