import SwiftUI

/// 推理引擎设置:本项目已切 Gemma-3n(端侧 4bit),主模型只走 MLX/GPU。
/// MNN/SME2 路径已停用(Gemma-3n 无 MNN 转换模型),引擎行保留但 MNN 置灰。
/// 切换只改持久化选择;下一次 AI 调用(prepare/generate)按新引擎加载。
struct InferenceSettingsView: View {
    @AppStorage("kk.inferenceEngine") private var engineRaw = EnginePreference.auto.rawValue
    // 云端 AI(Gemini)开关与 key —— 键名与 CloudAI 对齐,@AppStorage 写入即被后端读到。
    @AppStorage("cloud_ai_gemini_enabled") private var cloudEnabled = false
    @AppStorage("cloud_ai_gemini_key") private var cloudKey = ""
    @State private var modelService = ModelDownloadService.shared
    /// 性能自检改为当前页就地展开,不再 push 新页面。
    @State private var showSelfTest = false

    private var selected: EnginePreference {
        EnginePreference(rawValue: engineRaw) ?? .auto
    }

    /// 性能自检需要主模型(Gemma-3n,MLX)就绪。
    private var modelReady: Bool {
        modelService.states[.llm]?.phase == .ready
    }

    var body: some View {
        ScrollView {
            VStack(spacing: 12) {
                HStack {
                    Text("推理引擎")
                        .font(.tjTitle())
                        .foregroundStyle(Tj.Palette.text)
                    Spacer()
                }
                .padding(.top, 4)
                .padding(.bottom, 6)

                ForEach(EnginePreference.allCases, id: \.self) { engine in
                    engineRow(engine)
                }

                selfTestSection
                cloudSection
                noteCard
            }
            .padding(.horizontal, 16)
            .padding(.vertical, 20)
        }
        .background(Tj.Palette.sand.ignoresSafeArea())
        .onAppear { modelService.refreshStates() }
    }

    /// 性能自检入口:它是「动作/工具」而非引擎选择,所以做成描边动作按钮(TjGhostButton),
    /// 从视觉类别上和上方引擎/状态卡区分开。模型未就绪时禁用并给出下载提示而非死链。
    @ViewBuilder
    private var selfTestSection: some View {
        if modelReady {
            VStack(spacing: 12) {
                Button {
                    withAnimation(.easeInOut(duration: 0.22)) { showSelfTest.toggle() }
                } label: {
                    HStack(spacing: 8) {
                        Image(systemName: "gauge.with.needle")
                            .font(.tjScaled(15, weight: .semibold))
                        Text("性能自检")
                        Image(systemName: "chevron.down")
                            .font(.tjScaled(13, weight: .semibold))
                            .rotationEffect(.degrees(showSelfTest ? 180 : 0))
                    }
                    .frame(maxWidth: .infinity)
                }
                .buttonStyle(TjGhostButton())

                if showSelfTest {
                    ModelSelfTestView(embedded: true)
                        .transition(.opacity.combined(with: .move(edge: .top)))
                }
            }
            .padding(.top, 4)
        } else {
            VStack(spacing: 8) {
                HStack(spacing: 8) {
                    Image(systemName: "gauge.with.needle")
                        .font(.tjScaled(15, weight: .semibold))
                    Text("性能自检")
                }
                .font(.tjScaled(15, weight: .semibold))
                .foregroundStyle(Tj.Palette.text3)
                .frame(maxWidth: .infinity)
                .frame(height: 48)
                .background(Capsule().strokeBorder(Tj.Palette.line, lineWidth: 1))
                .opacity(0.6)

                Text("模型未就绪,前往「模型管理」下载后可用")
                    .font(.tjScaled(12))
                    .foregroundStyle(Tj.Palette.text3)
            }
            .padding(.top, 4)
        }
    }

    private func engineRow(_ engine: EnginePreference) -> some View {
        let available = isAvailable(engine)
        let isOn = (selected == engine)
        return Button {
            guard available else { return }
            engineRaw = engine.rawValue
        } label: {
            HStack(spacing: 12) {
                ZStack {
                    Circle().fill(isOn ? Tj.Palette.amber.opacity(0.25) : Tj.Palette.sand2)
                    Image(systemName: iconName(engine))
                        .font(.tjScaled(18))
                        .foregroundStyle(isOn ? Tj.Palette.ink : Tj.Palette.text2)
                }
                .frame(width: 44, height: 44)

                VStack(alignment: .leading, spacing: 2) {
                    Text(engine.displayName)
                        .font(.tjScaled(15, weight: .semibold))
                        .foregroundStyle(Tj.Palette.text)
                    Text(subtitle(engine, available: available))
                        .font(.tjScaled(12))
                        .foregroundStyle(Tj.Palette.text3)
                        .lineLimit(2)
                }
                Spacer()
                if isOn {
                    Image(systemName: "checkmark.circle.fill")
                        .font(.tjScaled(18))
                        .foregroundStyle(Tj.Palette.leaf)
                }
            }
            .padding(14)
            .tjCard()
            .opacity(available ? 1 : 0.45)
        }
        .buttonStyle(.plain)
        .disabled(!available)
    }

    /// .auto 永远可用;MLX 看自身可用性。MNN 已停用(Gemma-3n 无 MNN 模型),恒置灰。
    private func isAvailable(_ engine: EnginePreference) -> Bool {
        switch engine {
        case .auto: return true
        case .mnn:  return false
        case .mlx:  return InferenceEngine.mlx.isAvailable
        }
    }

    private func iconName(_ engine: EnginePreference) -> String {
        switch engine {
        case .auto: return "wand.and.stars"
        case .mnn:  return "cpu.fill"
        case .mlx:  return "bolt.fill"
        }
    }

    private func subtitle(_ engine: EnginePreference, available: Bool) -> String {
        switch engine {
        case .auto:
            // 已切 Gemma-3n,auto 恒解析为 MLX。
            return String(appLoc: "按本机配置选择 · 当前 MLX · GPU")
        case .mnn:
            return String(appLoc: "已停用:Gemma-3n 无 MNN 转换模型,统一走 MLX")
        case .mlx:
            return String(appLoc: "Metal GPU · 端侧推理 Gemma-3n E2B")
        }
    }

    private var cloudConfigured: Bool {
        cloudEnabled && !cloudKey.trimmingCharacters(in: .whitespaces).isEmpty
    }

    /// 云端 AI(Gemini)开关区。hybrid 的「云端」一侧:默认关(隐私优先),
    /// 开启并填入 AI Studio 的 key 后,「读报告原图 / 深度解读 / 多语言」走 Google Gemini。
    private var cloudSection: some View {
        VStack(alignment: .leading, spacing: 12) {
            HStack {
                Text("云端 AI · Gemini")
                    .font(.tjTitle())
                    .foregroundStyle(Tj.Palette.text)
                Spacer()
            }
            .padding(.top, 10)

            VStack(alignment: .leading, spacing: 12) {
                Toggle(isOn: $cloudEnabled) {
                    VStack(alignment: .leading, spacing: 2) {
                        Text("启用云端增强")
                            .font(.tjScaled(15, weight: .semibold))
                            .foregroundStyle(Tj.Palette.text)
                        Text("默认端侧 Gemma-3n;开启后「读报告原图 / 深度解读 / 多语言」走 Google Gemini。")
                            .font(.tjScaled(12))
                            .foregroundStyle(Tj.Palette.text3)
                    }
                }
                .tint(Tj.Palette.leaf)

                if cloudEnabled {
                    SecureField(String(appLoc: "粘贴 Google AI Studio 的 API Key"), text: $cloudKey)
                        .font(.tjScaled(14))
                        .textInputAutocapitalization(.never)
                        .autocorrectionDisabled()
                        .padding(12)
                        .background(RoundedRectangle(cornerRadius: Tj.Radius.md).fill(Tj.Palette.sand2))

                    HStack(spacing: 6) {
                        Image(systemName: cloudConfigured ? "checkmark.seal.fill" : "exclamationmark.circle")
                            .font(.tjScaled(13))
                            .foregroundStyle(cloudConfigured ? Tj.Palette.leaf : Tj.Palette.text3)
                        Text(cloudConfigured
                             ? String(appLoc: "已就绪 · \(AIRuntime.cloudLabel)")
                             : String(appLoc: "请填入 API Key(aistudio.google.com 免费获取)"))
                            .font(.tjScaled(12))
                            .foregroundStyle(Tj.Palette.text3)
                    }
                    Text("Key 仅存本机;断网或额度用尽时自动回退端侧 Gemma-3n,功能不中断。")
                        .font(.tjScaled(11))
                        .foregroundStyle(Tj.Palette.text3)
                }
            }
            .padding(14)
            .tjCard()
        }
    }

    private var noteCard: some View {
        Text("隐私优先:默认端侧 Gemma-3n(MLX · Metal GPU)推理,数据不出设备;仅在你开启「云端 AI」后,深度任务才走 Google Gemini。切换后下一次 AI 调用生效。")
            .font(.tjScaled(12))
            .foregroundStyle(Tj.Palette.text3)
            .frame(maxWidth: .infinity, alignment: .leading)
            .padding(14)
            .tjCard()
    }
}

#Preview {
    InferenceSettingsView()
}