//
//  HomeViewModel.swift
//  suixinkan
//
//  Created by Codex on 2026/6/22.
//

import Foundation

@MainActor
/// 首页 ViewModel，根据当前角色权限构建首页菜单列表。
final class HomeViewModel {
    var onChange: (() -> Void)?
    private(set) var menuItems: [HomeMenuItem] = [] { didSet { onChange?() } }

    /// 菜单排序权重，与旧工程和 Android 端保持一致。
    private let preferredOrder: [String] = [
        "space_settings",
        "album_list",
        "album_trailer",
        "wallet",
        "cloud_management",
        "cloud_storage_transit",
        "asset_management",
        "material_upload",
        "task_management",
        "schedule_management",
        "system_settings",
        "message_center",
        "checkin_points",
        "sample_management",
        "sample_upload",
        "live_stream_management",
        "scenicselection",
        "scenicapplication",
        "permission_apply",
        "permission_apply_status",
        "scenic_settlement",
        "scenic_settlement_review",
        "verification_order",
        "live_album",
        "pm",
        "location_report",
        "registration_invitation",
        "store",
        "fly",
        "pilot_cert",
        "task_management_editor",
        "deposit_order_detail",
        "deposit_order",
        "pm_manager",
        "pilot_controller",
        "/scenic-queue",
        "queue_management",
        "operating-area",
        "/scenic-order-manage",
        "photographer_orders"
    ]

    /// 从角色权限树扁平化出菜单项，按固定顺序排序并按 URI 别名去重。
    func buildMenus(from permissions: [RolePermissionResponse], currentRoleId: Int?) {
        let source: RolePermissionResponse?
        if let currentRoleId {
            source = permissions.first { $0.role.id == currentRoleId }
        } else {
            source = permissions.first
        }

        guard let source else {
            menuItems = []
            return
        }

        let permissionItems = flatten(source.role.permission)
        var seen = Set<String>()
        var deduplicated: [PermissionItem] = []
        for item in permissionItems where !item.uri.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty {
            if seen.insert(HomeMenuRouter.menuAliasKey(for: item.uri)).inserted {
                deduplicated.append(item)
            }
        }

        let preferredIndexMap = Dictionary(uniqueKeysWithValues: preferredOrder.enumerated().map { ($1, $0) })
        let sortedItems = deduplicated.sorted { lhs, rhs in
            let lhsRank = preferredIndexMap[lhs.uri] ?? Int.max
            let rhsRank = preferredIndexMap[rhs.uri] ?? Int.max
            if lhsRank != rhsRank {
                return lhsRank < rhsRank
            }
            let lhsIndex = deduplicated.firstIndex(where: { $0.id == lhs.id }) ?? Int.max
            let rhsIndex = deduplicated.firstIndex(where: { $0.id == rhs.id }) ?? Int.max
            return lhsIndex < rhsIndex
        }

        menuItems = sortedItems.map { item in
            HomeMenuItem(
                title: item.name.isEmpty ? HomeMenuRouter.title(for: item.uri) : item.name,
                uri: item.uri,
                iconSrc: item.iconSrc
            )
        }
    }

    /// 返回指定 URI 的展示标题。
    func title(for uri: String) -> String {
        HomeMenuRouter.title(for: uri)
    }

    /// 递归展开权限树。
    private func flatten(_ items: [PermissionItem]) -> [PermissionItem] {
        items.flatMap { item in
            [item] + flatten(item.children)
        }
    }
}