import Foundation

/// 已保存的主机（连接目标）。认证经 `AuthRef` 引用凭据或内联密码；出口经可选 `tailscaleID`。
struct SavedHost: Identifiable, Codable, Equatable {
    var id: UUID = UUID()
    var name: String
    var host: String
    var port: Int = 22
    /// 登录后引导 mosh 承载会话。
    var useMosh: Bool = false
    /// 登录后自动进入 tmux control mode（`tmux -CC new -A`）。默认开——tmux 是本项目四大核心之一，
    /// 会话复用/断线原样接回都靠它。服务器没装 tmux 时会自动降级为原生窗口并给安装引导。
    var useTmux: Bool = true
    /// tmux 会话名（`-s`）。nil = 用默认 `main`。
    var tmuxSession: String?
    /// 认证方式：内联用户名密码（快捷/旧数据归宿）或引用 Keychain 凭据。
    var auth: AuthRef
    /// 出口：nil = Direct 直连；否则经该 Tailscale 连接（egress profile，架构决策 §2.6）。
    var tailscaleID: UUID?
    /// 分组（首页「全部主机」的筛选 chips：生产 / 家里 / 云…）。nil = 未分组。
    var group: String?
    /// 系统描述（主机卡副行，如「macOS · M4 Max」）。纯展示，不参与连接。
    var os: String?

    /// 认证引用。
    enum AuthRef: Codable, Equatable {
        case inlinePassword(username: String, password: String)
        case credential(id: UUID)
    }

    init(id: UUID = UUID(), name: String, host: String, port: Int = 22,
         useMosh: Bool = false, useTmux: Bool = true, tmuxSession: String? = nil,
         auth: AuthRef, tailscaleID: UUID? = nil,
         group: String? = nil, os: String? = nil) {
        self.id = id
        self.name = name
        self.host = host
        self.port = port
        self.useMosh = useMosh
        self.useTmux = useTmux
        self.tmuxSession = tmuxSession
        self.auth = auth
        self.tailscaleID = tailscaleID
        self.group = group
        self.os = os
    }

    /// 展示地址行；内联凭据带用户名，引用凭据时用户名在凭据里，故只显示 host:port。
    var addressLine: String {
        if case .inlinePassword(let user, _) = auth, !user.isEmpty {
            return "\(user)@\(host):\(port)"
        }
        return "\(host):\(port)"
    }

    // MARK: - Codable（含旧 schema 迁移）

    enum CodingKeys: String, CodingKey {
        case id, name, host, port, useMosh, useTmux, tmuxSession, auth, tailscaleID, group, os
        // 旧字段
        case username, password
    }

    init(from decoder: Decoder) throws {
        let c = try decoder.container(keyedBy: CodingKeys.self)
        id = try c.decodeIfPresent(UUID.self, forKey: .id) ?? UUID()
        name = try c.decode(String.self, forKey: .name)
        host = try c.decode(String.self, forKey: .host)
        port = try c.decodeIfPresent(Int.self, forKey: .port) ?? 22
        useMosh = try c.decodeIfPresent(Bool.self, forKey: .useMosh) ?? false
        // 旧数据没有这两个键：tmux 默认开（此前是"从不自动进 tmux"，升级后按设计默认启用）。
        useTmux = try c.decodeIfPresent(Bool.self, forKey: .useTmux) ?? true
        tmuxSession = try c.decodeIfPresent(String.self, forKey: .tmuxSession)
        tailscaleID = try c.decodeIfPresent(UUID.self, forKey: .tailscaleID)
        group = try c.decodeIfPresent(String.self, forKey: .group)
        os = try c.decodeIfPresent(String.self, forKey: .os)
        if let auth = try c.decodeIfPresent(AuthRef.self, forKey: .auth) {
            self.auth = auth
        } else {
            // 旧 schema：inline username/password → inlinePassword（不自动造幽灵凭据）。
            let user = try c.decodeIfPresent(String.self, forKey: .username) ?? ""
            let pw = try c.decodeIfPresent(String.self, forKey: .password) ?? ""
            self.auth = .inlinePassword(username: user, password: pw)
        }
    }

    func encode(to encoder: Encoder) throws {
        var c = encoder.container(keyedBy: CodingKeys.self)
        try c.encode(id, forKey: .id)
        try c.encode(name, forKey: .name)
        try c.encode(host, forKey: .host)
        try c.encode(port, forKey: .port)
        try c.encode(useMosh, forKey: .useMosh)
        try c.encode(useTmux, forKey: .useTmux)
        try c.encodeIfPresent(tmuxSession, forKey: .tmuxSession)
        try c.encode(auth, forKey: .auth)
        try c.encodeIfPresent(tailscaleID, forKey: .tailscaleID)
        try c.encodeIfPresent(group, forKey: .group)
        try c.encodeIfPresent(os, forKey: .os)
    }
}

/// 主机列表持久化（Application Support 下 JSON）。凭据不入仓库；此文件只在设备本地。
@MainActor
final class HostStore: ObservableObject {
    @Published private(set) var hosts: [SavedHost] = []

    private let url: URL

    init() {
        let base = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask)[0]
        try? FileManager.default.createDirectory(at: base, withIntermediateDirectories: true)
        url = base.appendingPathComponent("hosts.json")
        load()
    }

    func add(_ host: SavedHost) {
        hosts.append(host)
        save()
    }

    func update(_ host: SavedHost) {
        guard let i = hosts.firstIndex(where: { $0.id == host.id }) else { return }
        hosts[i] = host
        save()
    }

    func remove(_ host: SavedHost) {
        hosts.removeAll { $0.id == host.id }
        save()
    }

    #if DEBUG
    /// 无头 UI 验证：把示意主机塞进内存（**不写盘**，不污染真实 hosts.json）。
    func injectFixtureHosts(_ hosts: [SavedHost]) {
        self.hosts = hosts
    }
    #endif

    private func load() {
        guard let data = try? Data(contentsOf: url),
              let decoded = try? JSONDecoder().decode([SavedHost].self, from: data) else { return }
        hosts = decoded
    }

    private func save() {
        guard let data = try? JSONEncoder().encode(hosts) else { return }
        try? data.write(to: url, options: .atomic)
    }
}