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

import Foundation

@MainActor
/// 权限上下文状态中心，保存角色权限、当前角色和扁平化权限 URI。
final class PermissionContext {

    var onChange: (() -> Void)?
    private(set) var rolePermissions: [RolePermissionResponse] = [] { didSet { onChange?() } }
    private(set) var permissionURIs: Set<String> = [] { didSet { onChange?() } }
    var currentRole: RoleInfo? { didSet { onChange?() } }

    /// 替换角色权限列表，并尽量按缓存角色 ID 保持当前角色。
    func replaceRolePermissions(_ rolePermissions: [RolePermissionResponse], currentRoleId: Int? = nil) {
        self.rolePermissions = rolePermissions
        currentRole = currentRoleId.flatMap { id in
            rolePermissions.first { $0.role.id == id }?.role
        } ?? currentRole.flatMap { role in
            rolePermissions.first { $0.role.id == role.id }?.role
        } ?? rolePermissions.first?.role
        permissionURIs = Set(Self.flattenPermissions(currentRole?.permission ?? []))
    }

    /// 切换当前角色，并同步账号上下文中的景区和门店选择。
    func selectRole(id roleId: Int, accountContext: AccountContext) {
        guard let rolePermission = rolePermissions.first(where: { $0.role.id == roleId }) else { return }
        currentRole = rolePermission.role
        permissionURIs = Set(Self.flattenPermissions(rolePermission.role.permission))

        let scenicScopes = Self.uniqueScenicScopes(from: rolePermission.scenic)
        accountContext.replaceScopes(
            scenic: scenicScopes,
            stores: accountContext.storeScopes,
            currentScenicId: accountContext.currentScenic?.id,
            currentStoreId: accountContext.currentStore?.id
        )
    }

    /// 判断当前角色是否拥有指定 URI 权限。
    func canAccess(_ uri: String) -> Bool {
        permissionURIs.contains(uri.trimmingCharacters(in: .whitespacesAndNewlines))
    }

    /// 返回当前角色关联的景区作用域。
    func currentRoleScenicScopes() -> [BusinessScope] {
        guard let currentRole else { return [] }
        guard let rolePermission = rolePermissions.first(where: { $0.role.id == currentRole.id }) else {
            return []
        }
        return Self.uniqueScenicScopes(from: rolePermission.scenic)
    }

    /// 清空权限上下文，通常在退出登录时调用。
    func reset() {
        rolePermissions = []
        permissionURIs = []
        currentRole = nil
    }

    /// 递归提取权限树里的非空 URI。
    private static func flattenPermissions(_ permissions: [PermissionItem]) -> [String] {
        permissions.flatMap { item -> [String] in
            let current = item.uri.trimmingCharacters(in: .whitespacesAndNewlines)
            let children = flattenPermissions(item.children)
            return current.isEmpty ? children : [current] + children
        }
    }

    /// 将角色关联景区去重并转换为业务作用域。
    private static func uniqueScenicScopes(from scenics: [ScenicInfo]) -> [BusinessScope] {
        var seen = Set<Int>()
        return scenics.compactMap { scenic in
            guard seen.insert(scenic.id).inserted else { return nil }
            return BusinessScope(
                id: scenic.id,
                name: scenic.name,
                kind: .scenic,
                status: scenic.status,
                address: scenic.location?.address,
                latitude: scenic.location?.lat,
                longitude: scenic.location?.lng,
                coverURLString: scenic.coverImg
            )
        }
    }
}