//
//  GroupMemberListVM.swift
//  QuickLocation
//
//  Created by 八条 on 2026/6/29.
//

import RxSwift
import RxRelay
import RxDataSources

// Used by the itinerary detail page in this module.
struct DrivingEventItem: IdentifiableType, Equatable {
    typealias Identity = String

    let identity: String
    let title: String
    let iconName: String
    let count: Int

    init(title: String, iconName: String, count: Int = 0) {
        self.identity = title
        self.title = title
        self.iconName = iconName
        self.count = count
    }
}

struct GroupMemberDirectorySection {
    let title: String
    let members: [GroupMemberModel]
}

extension GroupMemberDirectorySection: SectionModelType {
    typealias Item = GroupMemberModel

    init(original: GroupMemberDirectorySection, items: [GroupMemberModel]) {
        self.init(title: original.title, members: items)
    }

    var items: [GroupMemberModel] { members }
}

final class GroupMemberListVM {

    struct Output {
        let directoryItems: Observable<[GroupMemberDirectorySection]>
    }

    let groupKey: String
    let output: Output

    private let directoryItemsRelay = BehaviorRelay<[GroupMemberDirectorySection]>(value: [])
    private var owner: GroupMemberModel?
    private var members: [GroupMemberModel] = []
    private var searchKeyword = ""

    init(groupKey: String) {
        self.groupKey = groupKey
        output = Output(directoryItems: directoryItemsRelay.asObservable())
    }

    func loadData(group: GroupInfoModel, members: [GroupMemberModel]) {
        let sortedMembers = GroupMemberSorter.sorted(
            members,
            groupKey: group.group_key,
            currentUserId: AppContextManager.shared.userId
        )
        let owner = resolvedOwner(group: group, members: sortedMembers)
        self.owner = owner
        self.members = sortedMembers.filter { $0.user_id != owner?.user_id }
        publishDirectory()
    }

    func updateSearchKeyword(_ keyword: String) {
        searchKeyword = keyword.trimmingCharacters(in: .whitespacesAndNewlines)
        publishDirectory()
    }

    private func resolvedOwner(group: GroupInfoModel, members: [GroupMemberModel]) -> GroupMemberModel? {
        members.first {
            GroupOwnerMatcher.matches(userId: $0.user_id, groupKey: group.group_key)
        }
    }

    private func publishDirectory() {
        let matches: (GroupMemberModel) -> Bool = { [searchKeyword] member in
            searchKeyword.isEmpty || member.nick_name.localizedCaseInsensitiveContains(searchKeyword)
        }

        var sections: [GroupMemberDirectorySection] = []
        if let owner, matches(owner) {
            sections.append(GroupMemberDirectorySection(title: "圈主（1人）", members: [owner]))
        }

        let visibleMembers = members.filter(matches)
        if !visibleMembers.isEmpty {
            sections.append(GroupMemberDirectorySection(title: "圈成员（\(visibleMembers.count)人）", members: visibleMembers))
        }

        directoryItemsRelay.accept(sections)
    }
}