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

import Foundation

/// 首页常用应用存储服务，负责按当前角色权限过滤和持久化常用 URI。
struct HomeCommonMenuStore {
    static let storageKeyPrefix = "home.common.menu.uris.role."

    private let defaults: UserDefaults

    /// 初始化常用应用存储服务，并允许测试注入独立 UserDefaults。
    init(defaults: UserDefaults = .standard) {
        self.defaults = defaults
    }

    /// 按 Android 规则生成默认常用 URI：顶层权限顺序、可用权限过滤、别名去重，超过 4 个取前 4 个。
    static func defaultCommonURIs(
        orderedTopLevelURIs: [String],
        availableURIs: Set<String>
    ) -> [String] {
        let resolved = orderedTopLevelURIs.compactMap { uri -> String? in
            let trimmed = uri.trimmingCharacters(in: .whitespacesAndNewlines)
            guard !trimmed.isEmpty else { return nil }
            let canonical = HomeMenuRouter.canonicalURI(for: trimmed, availableURIs: availableURIs)
            return availableURIs.contains(canonical) ? canonical : nil
        }
        let deduplicated = unique(resolved)
        if deduplicated.count > 4 {
            return Array(deduplicated.prefix(4))
        }
        return deduplicated
    }

    /// 读取常用 URI；无角色时返回空，无保存或过滤后为空时写入 Android 对齐默认值。
    func load(
        menuItems: [HomeMenuItem],
        roleCode: String?,
        legacyRoleId: Int? = nil,
        topLevelPermissionURIs: [String]
    ) -> [String] {
        guard let roleCode, !roleCode.isEmpty else { return [] }
        migrateLegacyStorageIfNeeded(roleCode: roleCode, legacyRoleId: legacyRoleId)

        let availableURIs = Set(menuItems.map(\.uri))
        let key = storageKey(for: roleCode)
        let saved = defaults.stringArray(forKey: key)

        if let saved, !saved.isEmpty {
            let filtered = Self.unique(saved.compactMap { uri -> String? in
                let resolved = HomeMenuRouter.canonicalURI(for: uri, availableURIs: availableURIs)
                return availableURIs.contains(resolved) ? resolved : nil
            })
            if !filtered.isEmpty {
                save(filtered, roleCode: roleCode)
                return filtered
            }
        }

        let defaultURIs = Self.defaultCommonURIs(
            orderedTopLevelURIs: topLevelPermissionURIs,
            availableURIs: availableURIs
        )
        save(defaultURIs, roleCode: roleCode)
        return defaultURIs
    }

    /// 将指定 URI 加入常用应用，按别名避免重复添加。
    func add(_ uri: String, current: [String], menuItems: [HomeMenuItem], roleCode: String?) -> [String] {
        guard let roleCode, !roleCode.isEmpty else { return current }
        let availableURIs = Set(menuItems.map(\.uri))
        let resolved = HomeMenuRouter.canonicalURI(for: uri, availableURIs: availableURIs)
        guard availableURIs.contains(resolved) else { return current }
        guard !current.contains(where: { HomeMenuRouter.menuAliasKey(for: $0) == HomeMenuRouter.menuAliasKey(for: resolved) }) else {
            return current
        }
        let next = current + [resolved]
        save(next, roleCode: roleCode)
        return next
    }

    /// 从常用应用中移除指定 URI，同义 URI 会一起移除。
    func remove(_ uri: String, current: [String], roleCode: String?) -> [String] {
        guard let roleCode, !roleCode.isEmpty else { return current }
        let aliasKey = HomeMenuRouter.menuAliasKey(for: uri)
        let next = current.filter { HomeMenuRouter.menuAliasKey(for: $0) != aliasKey }
        save(next, roleCode: roleCode)
        return next
    }

    /// 保存指定角色的常用 URI。
    func save(_ uris: [String], roleCode: String) {
        defaults.set(Self.unique(uris), forKey: storageKey(for: roleCode))
    }

    /// 若新 key 无数据，则从 legacy role id key 一次性迁移常用菜单。
    func migrateLegacyStorageIfNeeded(roleCode: String, legacyRoleId: Int?) {
        let newKey = storageKey(for: roleCode)
        guard defaults.stringArray(forKey: newKey) == nil,
              let legacyRoleId,
              let legacyData = defaults.stringArray(forKey: legacyStorageKey(for: legacyRoleId)),
              !legacyData.isEmpty else {
            return
        }
        defaults.set(legacyData, forKey: newKey)
        defaults.removeObject(forKey: legacyStorageKey(for: legacyRoleId))
    }

    /// 生成按 role_code 隔离的 UserDefaults key。
    private func storageKey(for roleCode: String) -> String {
        Self.storageKeyPrefix + roleCode
    }

    /// 旧版按 numeric role id 存储的 key。
    private func legacyStorageKey(for roleId: Int) -> String {
        Self.storageKeyPrefix + String(roleId)
    }

    /// 按 URI 别名去重，保留首次出现的 URI。
    private static func unique(_ uris: [String]) -> [String] {
        var seen = Set<String>()
        return uris.filter { uri in
            seen.insert(HomeMenuRouter.menuAliasKey(for: uri)).inserted
        }
    }
}