dimensionhub/dimensionhub/Views/Index/IndexMainView.swift

//
//  IndexMainView.swift
//  dimensionhub
//
//  Created by 安礼成 on 2025/4/8.
//
import SwiftUI
import Combine

// 首页的主要窗口
struct IndexMainView: View {
    @Environment(\.modelContext) private var modelContext
    @EnvironmentObject var appNavigation: AppNavigation
    @AppStorage("userId") private var userId: String = Utils.defaultUserId()
    
    @State var indexModel = IndexModel()
    
    // 提示信息
    @State var showPrompt: Bool = false
    @State var promptMessage: String = ""

    // 是否显示日期弹出层
    @State private var selectGroupId: String = ""
    @State private var showDateNavPopover: Bool = false
    
    // 刷新逻辑
    @State private var headerRefreshing: Bool = false
    @State private var footerRefreshing: Bool = false
    @State private var noMore: Bool = false
    
    var body: some View {
        VStack(alignment: .center) {
            
            HStack(alignment: .center) {
                Text("亚次元")
                    .font(.system(size: 18, weight: .bold))
                    .padding([.top, .bottom], 5)
                Spacer()
                
                HStack {
                    Text("♡ \(indexModel.follow_num)")
                        .font(.system(size: 17))
                        .foregroundColor(.black)
                        .padding([.top, .bottom], 5)
                        .padding(.leading, 10)
                }
                .contentShape(Rectangle())
                .highPriorityGesture(
                    TapGesture().onEnded {
                        appNavigation.append(dest: .followList)
                    }
                )
                .zIndex(1)
            }
            .padding([.leading, .trailing], 15)
            .frame(height: 50)
            .background(Color(hex: "#F2F2F2"), ignoresSafeAreaEdges: .top)
            
            ScrollView(.vertical, showsIndicators: false) {
                Rectangle()
                    .frame(width: 0, height: 10)
                
                // 基于日期的更新列表
                LazyVStack(alignment: .center, spacing: 10) {
                    ForEach(indexModel.updateDramaGroups, id: \.group_id) { group in
                        DramaGroupView(group: group, model: indexModel) {
                            selectGroupId = group.group_id
                            indexModel.selectedDate = group.group_id
                            showDateNavPopover = true
                        }
                        .contentShape(Rectangle())
                    }
                }

                ProgressView()
                    .id(UUID())
                    .background(GeometryReader { geometry in
                        let minY = geometry.frame(in: .global).minY
                        Color.clear.preference(key: FooterOffsetPreferenceKey.self, value: Int(minY))
                    })
            }
            .frame(width: 370)
            .coordinateSpace(name: "indexScrollView")
            
            .onPreferenceChange(FooterOffsetPreferenceKey.self) { offset in
                // 延迟到当前帧结束更新state的值，避免导致循环更新的警告
                DispatchQueue.main.async {
                    indexModel.loadMorePublisher.send((userId, offset))
                }
            }
            .refreshable {
                guard !self.showDateNavPopover && !self.headerRefreshing else {
                    return
                }
                
                // 上拉刷新功能
                self.headerRefreshing = true
                Task {
                    await self.indexModel.loadMoreUpdateDramasTask(userId: self.userId, mode: .prev)
                    DispatchQueue.main.async {
                        self.headerRefreshing = false
                    }
                }
            }
            .overlay(alignment: .topTrailing) {
                HStack(alignment: .center) {
                    Button(action: {
                        appNavigation.append(dest: .search)
                    }) {
                        Image(systemName: "magnifyingglass")
                            .font(.system(size: 20))
                    }
                    
                    Spacer()
                    if let fixedDramaGroup = indexModel.fixedDramaGroup {
                        Text(fixedDramaGroup.group_name)
                            .font(.system(size: 18))
                            .fontWeight(.regular)
                            .onTapGesture {
                                selectGroupId = fixedDramaGroup.group_id
                                indexModel.selectedDate = fixedDramaGroup.group_id
                                showDateNavPopover = true
                            }
                    }
                }
                .padding([.top, .bottom], 8)
                .background(.white)
            }
        }
        .ignoresSafeArea(edges: .bottom)
        .popover(isPresented: $showDateNavPopover) {
            DateNavView(selectGroupId: self.$selectGroupId, showDateNavPopover: $showDateNavPopover) { selectedDate in
                Task {
                    await indexModel.loadDateUpdateDramas(userId: self.userId, date: selectedDate)
                }
            }
        }
        .alert(isPresented: $showPrompt) {
            Alert(title: Text("提示"), message: Text(self.promptMessage), dismissButton: .default(Text("OK")))
        }
        .task {
            await self.indexModel.loadData(userId: self.userId)
        }
        .onPreferenceChange(DramaGroupElementPreferenceKey.self) { frames in
            let visibleFrames = frames.filter { $0.value >= 0}
            if let minFrame = visibleFrames.min(by: { $0.value <= $1.value}) {
                DispatchQueue.main.async {
                    indexModel.setFixedDrameGroup(groupId: minFrame.key)
                }
            }
        }
        
    }
    
}

extension IndexMainView {
    
    // 显示分组信息
    struct DramaGroupView: View {
        @EnvironmentObject var appNav: AppNavigation

        let group: IndexModel.UpdateDramaGroup
        let model: IndexModel
        
        var onTap: () -> Void
        
        var body: some View {
            VStack(alignment: .center, spacing: 10) {
                HStack {
                    Spacer()
                    Text(group.group_name)
                        .font(.system(size: 18))
                        .fontWeight(.regular)
                        .onTapGesture {
                            onTap()
                        }
                }
                
                ForEach(group.items, id: \.id) { item in
                    Button(action: {
                        appNav.append(dest: .detail(id: item.id))
                    }) {
                        AsyncImage(url: URL(string: item.thumb)) { phase in
                            switch phase {
                            case .empty:
                                ProgressView()
                            case .success(let image):
                                image
                                    .resizable()
                                    .aspectRatio(contentMode: .fill)
                                    .frame(width: 370, height: 180)
                                    .clipped()
                            default:
                                Image("ph_img_big")
                                    .resizable()
                                    .aspectRatio(contentMode: .fill)
                                    .clipped()
                            }
                            
                        }
                        .frame(width: 370, height: 180)
                        .overlay(alignment: .topLeading) {
                            VStack(alignment: .leading, spacing: 8) {
                                Text(item.name)
                                    .font(.system(size: 16))
                                    .foregroundColor(.white)
                                    .lineLimit(1)
                                
                                Text(item.status)
                                    .font(.system(size: 12))
                                    .foregroundColor(.white)
                                    .lineLimit(1)
                            }
                            .padding(5)
                            .background(
                                Color.black.opacity(0.6)
                            )
                            .cornerRadius(5)
                            .padding(8)
                        }
                        .background(GeometryReader { geometry in
                            let height = geometry.size.height
                            let minY = geometry.frame(in: .named("indexScrollView")).minY
                            let y = minY >= 0 ? minY : minY + height
                            
                            Color.clear
                                .preference(key: DramaGroupElementPreferenceKey.self, value: [ group.group_id : y])
                        })
                    }
                }
            }
        }
    }
    
    
}

// MARK: PreferenceKey
extension IndexMainView {
    
    // 元素的坐标的距离变化, [groupId : minY]
    struct DramaGroupElementPreferenceKey: PreferenceKey {
        static var defaultValue: [String: CGFloat] = [:]
        
        static func reduce(value: inout [String: CGFloat], nextValue: () -> [String: CGFloat]) {
            value.merge(nextValue()) { $1 }
        }
    }
    
    // 底部的元素的坐标信息变化
    struct FooterOffsetPreferenceKey: PreferenceKey {
        static var defaultValue: Int = 0
        
        static func reduce(value: inout Int, nextValue: () -> Int) {
            value += nextValue()
        }
    }
    
}


#Preview {
    IndexMainView()
}