//
//  GroupViewModel.swift
//  QuickLocation
//

import Foundation
import RxSwift
import RxCocoa
import RxDataSources
import OpenIMSDK

typealias HotGroupListSectionModel = SectionModel<String, GroupInfoModel>
typealias CircleListSectionModel = SectionModel<String, GroupCellData>

/// 群聊 cell 数据（融合群信息 + 会话信息）
struct GroupCellData {
    let groupInfo: OIMGroupInfo
    let unreadCount: Int
    let lastMsgTime: Int // ms timestamp
    let localIcon: UIImage
}

final class GroupViewModel {

    struct Output {
        let hotGroups: Observable<[HotGroupListSectionModel]>
        let createdSections: Observable<[CircleListSectionModel]>
        let joinedSections: Observable<[CircleListSectionModel]>
        let segmentTitles: Driver<[String]>
    }

    let output: Output

    private let hotGroupSectionedItems = PublishSubject<[HotGroupListSectionModel]>()
    private let createdSectionsSubject = PublishSubject<[CircleListSectionModel]>()
    private let joinedSectionsSubject = PublishSubject<[CircleListSectionModel]>()

    let segmentTitles = BehaviorRelay<[String]>(value: ["我创建的圈子", "我加入的圈子"])

    var groupList: [GroupInfoModel] = []
    
    private var cachedGroups: [OIMGroupInfo] = []
    private var cachedConversations: [OIMConversationInfo] = []

    /// 当前群的本地图标
    func getLocalIcon(groupId: String) -> UIImage {
        groupList.first { groupId == $0.group_key }?.groupIcon ?? UIImage(named: "GroupIcon/1")!
    }
    
    /// 热门酷圈
    func loadHotGroupData(_ list: [GroupInfoModel]) {
        hotGroupSectionedItems.onNext(list.mapSection())
    }

    /// 加载群列表（全量刷新）
    func loadIMGroups(_ groups: [OIMGroupInfo], conversations: [OIMConversationInfo] = []) {
        if !groups.isEmpty { cachedGroups = groups }
        if !conversations.isEmpty { cachedConversations = conversations }
        reloadData()
    }

    /// 仅更新会话元数据（未读、时间）- 消息监听回调（只返回变更的会话，需合并）
    func updateConversations(_ conversations: [OIMConversationInfo]) {
        var merged: [String: OIMConversationInfo] = [:]
        for c in cachedConversations { if let gid = c.groupID { merged[gid] = c } }
        for c in conversations { if let gid = c.groupID { merged[gid] = c } }
        cachedConversations = Array(merged.values)
        reloadData()
    }

    private func reloadData() {
        let currentUserId = AppContextManager.shared.userId
        let convMap: [String: OIMConversationInfo] = {
            var m: [String: OIMConversationInfo] = [:]
            for c in cachedConversations where c.groupID != nil && !(c.groupID?.isEmpty ?? true) {
                m[c.groupID!] = c
            }
            return m
        }()

        var created: [GroupCellData] = []
        var joined: [GroupCellData] = []

        for g in cachedGroups {
            let conv = convMap[g.groupID ?? ""]
            let data = GroupCellData(
                groupInfo: g,
                unreadCount: Int(conv?.unreadCount ?? 0),
                lastMsgTime: Int(conv?.latestMsgSendTime ?? 0),
                localIcon: getLocalIcon(groupId: g.groupID ?? "")
            )
            if g.ownerUserID == currentUserId || g.creatorUserID == currentUserId {
                created.append(data)
            } else {
                joined.append(data)
            }
        }

        createdSectionsSubject.onNext(created.mapSection())
        joinedSectionsSubject.onNext(joined.mapSection())
    }

    // MARK: - Init
    init() {
        output = Output(
            hotGroups: hotGroupSectionedItems.asObservable(),
            createdSections: createdSectionsSubject.asObservable(),
            joinedSections: joinedSectionsSubject.asObservable(),
            segmentTitles: segmentTitles.asDriver()
        )
    }
}