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

import Foundation
import RxSwift
import RxCocoa
import RxDataSources
import OpenIMSDK
import ObjectMapper

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

/// 群聊 cell 数据：圈子集合以业务 `groups` 为准，IM 会话只补未读/预览/时间
struct GroupCellData {
    let group: GroupInfoModel
    let unreadCount: Int
    let lastMsgTime: Int // ms timestamp
    let lastMsgPreview: String

    var tags: [String] { Array(group.labels.prefix(2)) }
    var iconURL: String { group.groupIconURL }
    var localIcon: UIImage { group.groupIcon }
}

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"])

    private(set) var groupList: [GroupInfoModel] = []
    private var cachedConversations: [OIMConversationInfo] = []
    
    /// 热门酷圈
    func loadHotGroupData(_ list: [GroupInfoModel]) {
        hotGroupSectionedItems.onNext(list.mapSection())
    }
    
    lazy var hotGroupCellAction: Action<GroupInfoModel, Void> = { this in
        return Action { model in
            AppRouter.push(Route.groupInfo, userInfo: ["groupInfo": model.toJSON()])
            return .empty()
        }
    }(self)

    /// 业务圈子列表（与首页切圈弹层同一份 `groups`）
    func applyBusinessGroups(_ list: [GroupInfoModel]) {
        groupList = list
        reloadData()
    }

    /// 全量刷新 IM 会话（未读、最后一条、时间）
    func loadConversations(_ conversations: [OIMConversationInfo]) {
        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 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
        }()

        func cellData(for group: GroupInfoModel) -> GroupCellData {
            let conv = convMap[group.group_key]
            return GroupCellData(
                group: group,
                unreadCount: Int(conv?.unreadCount ?? 0),
                lastMsgTime: Int(conv?.latestMsgSendTime ?? 0),
                lastMsgPreview: Self.previewText(from: conv?.latestMsg)
            )
        }

        func sortedByLastMsg(_ items: [GroupCellData]) -> [GroupCellData] {
            items.sorted { lhs, rhs in
                if lhs.lastMsgTime != rhs.lastMsgTime {
                    return lhs.lastMsgTime > rhs.lastMsgTime
                }
                return lhs.group.group_key < rhs.group.group_key
            }
        }

        let all = sortedByLastMsg(groupList.map(cellData(for:)))
        let created = sortedByLastMsg(groupList.filter(\.is_owner).map(cellData(for:)))

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

    private static func previewText(from msg: OIMMessageInfo?) -> String {
        guard let msg else { return "" }
        let body: String
        switch msg.contentType {
        case .image: body = "[图片]"
        case .audio: body = "[语音]"
        case .video: body = "[视频]"
        case .file: body = "[文件]"
        case .location: body = "[位置]"
        case .at: body = Self.displayBody(msg.atTextElem?.text ?? "[消息]")
        case .quote: body = Self.displayBody(msg.quoteElem?.text ?? "[消息]")
        case .face: body = "[表情]"
        default:
            body = Self.displayBody(msg.textElem?.content ?? msg.content ?? "")
        }
        let name = msg.senderNickname ?? ""
        if name.isEmpty { return body }
        if body.isEmpty { return name }
        return "\(name): \(body)"
    }

    private static func displayBody(_ text: String) -> String {
        if text.hasPrefix("js_emoji:") { return "[表情]" }
        return text
    }

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