//
//  AvatarIconListView.swift
//  QuickLocation
//
//  Created by 八条 on 2026/6/11.
//

import UIKit

class AvatarIconListView: UIView {

    var selectedIndex: Int = 1 {
        didSet {
            updatePreview()
            iconCollectionView.reloadData()
        }
    }

    private var currentHeadPic: String = ""

    var selectedHeadPic: String {
        if selectedIndex > 0 {
            return "\(selectedIndex)"
        }
        return currentHeadPic
    }

    let saveBtn = UIButton(type: .custom)
    var onBadgeTap: (() -> Void)?
    var onIconSelected: (() -> Void)?

    private var iconImgList: [UIImage] = []
    private let collectionLayout = CollectionHFlowLayout()
    private var lastLayoutWidth: CGFloat = 0
    private var collectionHeightConstraint: NSLayoutConstraint?
    private var didScrollToInitialPage = false

    private let columns = 4
    private let rows = 2
    private let hSpacing: CGFloat = 12
    private let vSpacing: CGFloat = 12
    private let cardSideInset: CGFloat = 18

    override init(frame: CGRect) {
        super.init(frame: .zero)
        backgroundColor = .white
        for i in 1...16 {
            if let img = UIImage(named: "UserIcon/\(i)") {
                iconImgList.append(img)
            }
        }
        setupUI()
        updatePreview()
        updatePageControl()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        updateGridLayout(for: bounds.width)
        scrollToSelectedPageIfNeeded()
    }

    private func setupUI() {
        addSubview(navView)
        navView.layoutChain.edges(excludingEdge: .bottom).height(kNaviHeight)

        addSubview(previewWrap)
        previewWrap.addSubview(selectedIconView)
        addSubview(badgeView)
        previewWrap.isUserInteractionEnabled = false
        addSubview(gridCard)
        gridCard.addSubview(titleLab)
        gridCard.addSubview(iconCollectionView)
        gridCard.addSubview(pageControl)
        addSubview(saveBtn)

        previewWrap.layoutChain
            .topToBottomOfView(navView, offset: 36)
            .centerX()
            .width(120)
            .height(120)

        selectedIconView.layoutChain.edges(all: 6)

        badgeView.layoutChain
            .rightToView(previewWrap, offset: 4)
            .bottomToView(previewWrap, offset: 4)
            .width(40)
            .height(40)

        saveBtn.setTitle("保存", for: .normal)
        saveBtn.setTitleColor(.white, for: .normal)
        saveBtn.titleLabel?.font = FontManager.boboBold(18)
        saveBtn.setBackgroundImage(UIImage(named: "Common/button_bg_2"), for: .normal)
        saveBtn.layer.cornerRadius = 28
        saveBtn.clipsToBounds = true
        saveBtn.isHidden = true
        saveBtn.layoutChain
            .edgesHorzontal(30)
            .bottom(kSafeBottomMargin + 13)
            .height(56)

        gridCard.layoutChain
            .topToBottomOfView(previewWrap, offset: 48)
            .edgesHorzontal(15)

        titleLab.layoutChain
            .top(20)
            .centerX()

        iconCollectionView.layoutChain
            .topToBottomOfView(titleLab, offset: 16)
            .edgesHorzontal()
        collectionHeightConstraint = iconCollectionView.heightAnchor.constraint(equalToConstant: 148)
        collectionHeightConstraint?.isActive = true

        pageControl.layoutChain
            .topToBottomOfView(iconCollectionView, offset: 8)
            .centerX()
            .bottom(10)
            .height(16)

        collectionLayout.rows = rows
        collectionLayout.colums = columns
        collectionLayout.hSpacing = hSpacing
        collectionLayout.vSpacing = vSpacing
        bringSubviewToFront(badgeView)
    }

    func configure(headPic: String) {
        currentHeadPic = headPic
        if HeadPic.isRemote(headPic) {
            selectedIndex = 0
            selectedIconView.setHeadPic(headPic)
        } else {
            selectedIndex = max(headPic.integer, 1)
        }
    }

    func setPreviewImage(_ image: UIImage) {
        selectedIndex = 0
        selectedIconView.image = image
    }

    @objc private func handleBadgeTap() {
        onBadgeTap?()
    }

    private func updatePreview() {
        guard selectedIndex > 0 else { return }
        selectedIconView.image = UIImage(named: "UserIcon/\(selectedIndex)")
    }

    private func updatePageControl() {
        let pageSize = columns * rows
        let pageCount = max(Int(ceil(Double(iconImgList.count) / Double(pageSize))), 1)
        pageControl.numberOfPages = pageCount
        pageControl.isHidden = pageCount <= 1
    }

    private func updateGridLayout(for width: CGFloat) {
        let cardWidth = gridCard.bounds.width > 1
            ? gridCard.bounds.width
            : max(width - 30, 0)
        guard cardWidth > 0, abs(cardWidth - lastLayoutWidth) > 0.5 else { return }
        lastLayoutWidth = cardWidth

        let available = cardWidth - cardSideInset * 2
        let itemW = floor((available - hSpacing * CGFloat(columns - 1)) / CGFloat(columns))
        collectionLayout.itemSize = CGSize(width: itemW, height: itemW)
        collectionLayout.sectionInset = UIEdgeInsets(top: 0, left: cardSideInset, bottom: 0, right: cardSideInset)
        collectionLayout.invalidateLayout()

        let collectionHeight = itemW * CGFloat(rows) + vSpacing * CGFloat(rows - 1)
        collectionHeightConstraint?.constant = collectionHeight
    }

    private func scrollToSelectedPageIfNeeded() {
        guard !didScrollToInitialPage,
              iconCollectionView.bounds.width > 1,
              collectionLayout.itemSize.width > 0 else { return }
        didScrollToInitialPage = true
        let pageSize = columns * rows
        let page = max((selectedIndex - 1) / pageSize, 0)
        pageControl.currentPage = page
        iconCollectionView.setContentOffset(
            CGPoint(x: CGFloat(page) * iconCollectionView.bounds.width, y: 0),
            animated: false
        )
    }

    private func updateCurrentPage() {
        let width = iconCollectionView.bounds.width
        guard width > 0 else { return }
        pageControl.currentPage = Int(round(iconCollectionView.contentOffset.x / width))
    }

    lazy var navView: BaseNavigationView = {
        BaseNavigationView(title: "")
    }()

    private lazy var previewWrap: UIView = {
        let view = UIView()
        view.backgroundColor = .white
        view.layer.cornerRadius = 32
        view.layer.shadowColor = UIColor.black.cgColor
        view.layer.shadowOpacity = 0.08
        view.layer.shadowOffset = CGSize(width: 0, height: 6)
        view.layer.shadowRadius = 14
        return view
    }()

    lazy var selectedIconView: UIImageView = {
        let view = UIImageView()
        view.contentMode = .scaleAspectFill
        view.clipsToBounds = true
        view.layer.cornerRadius = 26
        return view
    }()

    private lazy var badgeView: UIButton = {
        let btn = UIButton(type: .custom)
        btn.setImage(UIImage(named: "Mine/avatar_album_badge"), for: .normal)
        btn.imageView?.contentMode = .scaleAspectFit
        btn.extendEdgeInsets = UIEdgeInsets(top: 12, left: 12, bottom: 12, right: 12)
        btn.addTarget(self, action: #selector(handleBadgeTap), for: .touchUpInside)
        return btn
    }()

    private lazy var gridCard: UIView = {
        let view = UIView()
        view.backgroundColor = UIColor(hexStr: "#F5F6F8")
        view.layer.cornerRadius = 40
        return view
    }()

    private lazy var titleLab: UILabel = {
        let label = UILabel()
        label.text = "选择头像"
        label.font = .systemFont(ofSize: 16, weight: .bold)
        label.textColor = ThemeManager.shared.color.titleAuxColor
        return label
    }()

    private lazy var iconCollectionView: UICollectionView = {
        let cv = UICollectionView(frame: .zero, collectionViewLayout: collectionLayout)
        cv.backgroundColor = .clear
        cv.isPagingEnabled = true
        cv.bounces = false
        cv.showsHorizontalScrollIndicator = false
        cv.contentInsetAdjustmentBehavior = .never
        cv.register(AvatarIconCell.self)
        cv.delegate = self
        cv.dataSource = self
        return cv
    }()

    private lazy var pageControl: UIPageControl = {
        let control = UIPageControl()
        control.currentPage = 0
        control.isUserInteractionEnabled = false
        control.currentPageIndicatorTintColor = UIColor(hexStr: "#16B3FF")
        control.pageIndicatorTintColor = UIColor(hexStr: "#7AD6FF", alpha: 0.4)
        return control
    }()
}

extension AvatarIconListView: UICollectionViewDelegate, UICollectionViewDataSource {

    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        iconImgList.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(for: indexPath) as AvatarIconCell
        cell.configure(img: iconImgList[indexPath.item], isSelected: selectedIndex == indexPath.item + 1)
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        selectedIndex = indexPath.item + 1
        onIconSelected?()
    }

    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        updateCurrentPage()
    }

    func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
        if !decelerate {
            updateCurrentPage()
        }
    }
}

final class AvatarIconCell: UICollectionViewCell {

    func configure(img: UIImage, isSelected: Bool) {
        iconImgView.image = img
        contentView.layer.borderColor = isSelected
            ? UIColor(hexStr: "#16B3FF").cgColor
            : UIColor.clear.cgColor
    }

    private func setupUI() {
        contentView.backgroundColor = .clear
        contentView.layer.cornerRadius = 18
        contentView.layer.borderWidth = 2
        contentView.clipsToBounds = true

        contentView.addSubview(iconImgView)
        iconImgView.layoutChain.edges(all: 2)
    }

    private lazy var iconImgView: UIImageView = {
        let view = UIImageView()
        view.backgroundColor = .clear
        view.contentMode = .scaleAspectFill
        view.clipsToBounds = true
        view.layer.cornerRadius = 16
        return view
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
        setupUI()
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}