//
//  LNIMOfficialMessageViewController.swift
//  Lanu
//
//  Created by OneeChan on 2025/12/10.
//

import Foundation
import UIKit
import SnapKit


extension UIView {
    func pushToOfficialMessage(uid: String) {
        let vc = LNIMOfficialMessageViewController(uid: uid)
        navigationController?.pushViewController(vc, animated: true)
    }
}


class LNIMOfficialMessageViewController: LNViewController {
    private let viewModel: LNIMChatViewModel
    
    private let tableView = UITableView()
    
    init(uid: String) {
        viewModel = LNIMChatViewModel(userId: LNIMOfficialIds.officialMessage.rawValue)
        super.init(nibName: nil, bundle: nil)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        setupViews()
        LNEventDeliver.addObserver(self)
        
        loadData()
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        
        viewModel.cleanUnread()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

extension LNIMOfficialMessageViewController {
    private func loadData() {
        viewModel.loadNextPage { [weak self] success, isFirst in
            guard let self else { return }
            guard success else { return }
            
            let oldHeight = tableView.contentSize.height
            tableView.reloadData()
            if isFirst {
                tableView.scrollToBottom(animated: false)
            } else {
                tableView.layoutIfNeeded()
                
                let newOffset = tableView.contentSize.height - oldHeight
                
                tableView.scrollRectToVisible(
                    .init(x: 0, y: newOffset,
                          width: tableView.bounds.width,
                          height: tableView.bounds.height),
                    animated: false)
            }
        }
    }
}

extension LNIMOfficialMessageViewController: LNIMChatViewModelNotify {
    func onIMMessageDataChanged(viewModel: LNIMChatViewModel, index: Int, type: LNIMChatDataSourceChangeType, toBottom: Bool) {
        guard viewModel.userId == self.viewModel.userId else { return }
        
        switch type {
        case .insert: tableView.reloadData()
        case .delete: tableView.reloadData()
        case .reload: tableView.reloadRows(at: [.init(row: index, section: 0)], with: .fade)
        }
        
        if toBottom {
            tableView.scrollToBottom()
        }
    }
    
    func onIMMessageDatasChanged(viewModel: LNIMChatViewModel, indexs: [IndexPath], type: LNIMChatDataSourceChangeType, toBottom: Bool) {
        guard viewModel.userId == self.viewModel.userId else { return }
        
        switch type {
        case .insert: tableView.reloadData()
        case .delete: tableView.reloadData()
        case .reload: tableView.reloadRows(at: indexs, with: .fade)
        }
        
        if toBottom {
            tableView.scrollToBottom()
        }
    }
}

extension LNIMOfficialMessageViewController: UITableViewDataSource, UITableViewDelegate {
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        viewModel.allMessage.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let data = viewModel.allMessage[indexPath.row]
        
        switch data.type {
        case .system:
            let cell = tableView.dequeueReusableCell(withIdentifier: LNIMChatSystemMessageCell.className, for: indexPath) as! LNIMChatSystemMessageCell
            cell.update(data)
            return cell
        case .official:
            if let message: LNIMOfficialMessage = data.decodeCustomMessage() {
                let cell = tableView.dequeueReusableCell(withIdentifier: LNIMOfficialMessageCell.className, for: indexPath) as! LNIMOfficialMessageCell
                cell.update(message)
                return cell
            }
        default :
            break
        }
        return tableView.dequeueReusableCell(withIdentifier: LNIMChatUnknownMessageCell.className, for: indexPath)
    }
    
    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        guard scrollView == tableView else { return }
        if tableView.contentOffset.y <= 0 {
            loadData()
        }
    }
    
    func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) {
        guard scrollView == tableView else { return }
        if tableView.contentOffset.y <= 0 {
            loadData()
        }
    }
}

extension LNIMOfficialMessageViewController {
    private func setupViews() {
        view.backgroundColor = .primary_1
        
        title = viewModel.userId == LNIMOfficialIds.officialMessage.rawValue ? .init(key: "A00091") : .init(key: "A00099")
        
        tableView.backgroundColor = .clear
        tableView.separatorStyle = .none
        tableView.allowsSelection = false
        tableView.register(LNIMOfficialMessageCell.self, forCellReuseIdentifier: LNIMOfficialMessageCell.className)
        tableView.register(LNIMChatSystemMessageCell.self, forCellReuseIdentifier: LNIMChatSystemMessageCell.className)
        tableView.register(LNIMChatUnknownMessageCell.self, forCellReuseIdentifier: LNIMChatUnknownMessageCell.className)
        tableView.dataSource = self
        tableView.delegate = self
        view.addSubview(tableView)
        tableView.snp.makeConstraints { make in
            make.horizontalEdges.equalToSuperview()
            make.top.equalToSuperview()
            make.bottom.equalTo(view.safeAreaLayoutGuide.snp.bottom)
        }
    }
}