//
//  PhotoPickerView.swift
//  QuickLocation
//

import UIKit
import Photos

final class PhotoPickerView: UIView {

    var onClose: (() -> Void)?
    var onToggleAlbum: (() -> Void)?
    var onPreview: (() -> Void)?
    var onConfirm: (() -> Void)?
    var onSelectAsset: ((Int) -> Void)?
    var onPickAlbum: ((Int) -> Void)?

    var isAlbumOpen = false {
        didSet { applyAlbumOpen() }
    }

    private let store: PhotoPickerStore
    private let maxCount: Int
    private var selectedIds: [String] = []
    private var currentAlbumIndex = 0
    private var lastGridWidth: CGFloat = 0

    init(store: PhotoPickerStore, maxCount: Int) {
        self.store = store
        self.maxCount = maxCount
        super.init(frame: .zero)
        backgroundColor = UIColor(hexStr: "#2C2C2E")
        setupUI()
        applyAlbumOpen()
        updateBottomBar(selectedCount: 0)
    }

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

    override func layoutSubviews() {
        super.layoutSubviews()
        let width = collectionView.bounds.width
        if width > 1, abs(width - lastGridWidth) > 0.5 {
            lastGridWidth = width
            collectionView.collectionViewLayout.invalidateLayout()
        }
    }

    func reloadGrid() {
        collectionView.reloadData()
    }

    func bindAlbumStore(_ store: PhotoPickerStore) {
        albumListView.bindStore(store)
    }

    func reloadAlbums(currentIndex: Int) {
        currentAlbumIndex = currentIndex
        albumListView.reload(albums: store.albums, selectedIndex: currentIndex)
        let title = store.albums[safe: currentIndex]?.title ?? "最近项目"
        albumTitleLab.text = title
    }

    func applySelection(_ ids: [String]) {
        selectedIds = ids
        updateBottomBar(selectedCount: ids.count)
        collectionView.reloadData()
    }

    func showLimitToast() {
        limitBanner.isHidden = false
        NSObject.cancelPreviousPerformRequests(withTarget: self, selector: #selector(hideLimitToast), object: nil)
        perform(#selector(hideLimitToast), with: nil, afterDelay: 1.8)
    }

    func thumbnailSize() -> CGSize {
        let side = collectionView.bounds.width > 0
            ? (collectionView.bounds.width - 3) / 4
            : (UIScreen.main.bounds.width - 3) / 4
        return CGSize(width: side, height: side)
    }

    // MARK: - UI

    private lazy var closeBtn: UIButton = {
        let btn = UIButton(type: .custom)
        btn.setImage(UIImage(named: "PhotoPicker/btn_close"), for: .normal)
        btn.extendEdgeInsets = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)
        btn.addTarget(self, action: #selector(tapClose), for: .touchUpInside)
        return btn
    }()

    private lazy var albumTitleBtn: UIControl = {
        let control = UIControl()
        control.backgroundColor = UIColor.white.withAlphaComponent(0.12)
        control.cornerRadius = 16
        control.addTarget(self, action: #selector(tapAlbum), for: .touchUpInside)
        return control
    }()

    private lazy var albumTitleLab: UILabel = {
        let label = UILabel()
        label.font = .systemFont(ofSize: 15, weight: .medium)
        label.textColor = .white
        label.text = "最近项目"
        return label
    }()

    private lazy var albumArrowView: UIImageView = {
        let iv = UIImageView(image: UIImage(named: "PhotoPicker/btn_album_arrow"))
        iv.contentMode = .scaleAspectFit
        return iv
    }()

    lazy var collectionView: UICollectionView = {
        let layout = UICollectionViewFlowLayout()
        layout.minimumInteritemSpacing = 1
        layout.minimumLineSpacing = 1
        layout.sectionInset = .zero
        let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
        cv.backgroundColor = UIColor(hexStr: "#2C2C2E")
        cv.register(PhotoPickerCell.self, forCellWithReuseIdentifier: "cell")
        cv.dataSource = self
        cv.delegate = self
        cv.alwaysBounceVertical = true
        return cv
    }()

    private lazy var dimView: UIControl = {
        let view = UIControl()
        view.backgroundColor = UIColor.black.withAlphaComponent(0.45)
        view.addTarget(self, action: #selector(tapAlbum), for: .touchUpInside)
        return view
    }()

    private lazy var albumListView: PhotoPickerAlbumView = {
        let view = PhotoPickerAlbumView()
        view.onSelect = { [weak self] index in
            self?.onPickAlbum?(index)
        }
        return view
    }()

    private lazy var bottomBar: UIView = {
        let view = UIView()
        view.backgroundColor = UIColor(hexStr: "#1C1C1E")
        return view
    }()

    private lazy var previewBtn: UIButton = {
        let btn = UIButton(type: .custom)
        btn.setTitle("预览", for: .normal)
        btn.setTitleColor(UIColor.white.withAlphaComponent(0.35), for: .disabled)
        btn.setTitleColor(.white, for: .normal)
        btn.titleLabel?.font = .systemFont(ofSize: 16)
        btn.contentHorizontalAlignment = .left
        btn.addTarget(self, action: #selector(tapPreview), for: .touchUpInside)
        return btn
    }()

    private lazy var confirmBtn: UIButton = {
        let btn = UIButton(type: .custom)
        btn.setTitle("确认", for: .normal)
        btn.setTitleColor(.white, for: .normal)
        btn.titleLabel?.font = .systemFont(ofSize: 16, weight: .medium)
        btn.backgroundColor = UIColor(hexStr: "#007AFF")
        btn.cornerRadius = 8
        btn.addTarget(self, action: #selector(tapConfirm), for: .touchUpInside)
        return btn
    }()

    private lazy var limitBanner: UIView = {
        let view = UIView()
        view.backgroundColor = UIColor(hexStr: "#3A3A3C")
        view.isHidden = true
        let icon = UILabel()
        icon.text = "!"
        icon.textColor = .white
        icon.font = .systemFont(ofSize: 12, weight: .bold)
        icon.textAlignment = .center
        icon.backgroundColor = .clear
        icon.layer.borderColor = UIColor.white.cgColor
        icon.layer.borderWidth = 1.2
        icon.layer.cornerRadius = 8
        icon.clipsToBounds = true
        let label = UILabel()
        label.text = "最多选取\(maxCount)张图片哦~"
        label.textColor = .white
        label.font = .systemFont(ofSize: 14)
        view.addSubview(icon)
        view.addSubview(label)
        icon.layoutChain.left(24).centerY().width(16).height(16)
        label.layoutChain.leftToRightOfView(icon, offset: 8).centerY()
        return view
    }()

    private var albumListHeight: NSLayoutConstraint?

    private func setupUI() {
        addSubview(closeBtn)
        addSubview(albumTitleBtn)
        albumTitleBtn.addSubview(albumTitleLab)
        albumTitleBtn.addSubview(albumArrowView)
        addSubview(collectionView)
        addSubview(dimView)
        addSubview(albumListView)
        addSubview(limitBanner)
        addSubview(bottomBar)
        bottomBar.addSubview(previewBtn)
        bottomBar.addSubview(confirmBtn)

        closeBtn.layoutChain
            .left(16)
            .width(32)
            .height(32)
        closeBtn.topAnchor.constraint(equalTo: safeAreaLayoutGuide.topAnchor, constant: 6).isActive = true

        albumTitleBtn.layoutChain
            .centerX()
            .centerY(closeBtn)
            .height(32)

        albumTitleLab.layoutChain
            .left(12)
            .centerY()
        albumArrowView.layoutChain
            .leftToRightOfView(albumTitleLab, offset: 6)
            .right(8)
            .centerY()
            .width(20)
            .height(20)

        collectionView.layoutChain
            .topToBottomOfView(closeBtn, offset: 10)
            .left()
            .right()

        bottomBar.layoutChain
            .left()
            .right()
            .bottom()
            .topToBottomOfView(collectionView)

        let bottomH = 56 + kSafeBottomMargin
        bottomBar.layoutChain.height(bottomH)

        previewBtn.layoutChain
            .left(20)
            .top(16)
            .height(24)
        confirmBtn.layoutChain
            .right(16)
            .top(10)
            .width(88)
            .height(36)

        limitBanner.layoutChain
            .left()
            .right()
            .bottomToTopOfView(bottomBar)
            .height(44)

        dimView.layoutChain
            .topToBottomOfView(closeBtn, offset: 10)
            .left()
            .right()
            .bottomToTopOfView(bottomBar)

        albumListView.layoutChain
            .topToView(dimView)
            .left()
            .right()
        albumListHeight = albumListView.heightAnchor.constraint(equalToConstant: 0)
        albumListHeight?.isActive = true
    }

    private func applyAlbumOpen() {
        dimView.isHidden = !isAlbumOpen
        albumListView.isHidden = !isAlbumOpen
        let count = store.albums.count
        let rowH: CGFloat = 64
        let maxH = min(CGFloat(count) * rowH, UIScreen.main.bounds.height * 0.42)
        albumListHeight?.constant = isAlbumOpen ? maxH : 0
        UIView.animate(withDuration: 0.22) {
            self.albumArrowView.transform = self.isAlbumOpen
                ? CGAffineTransform(rotationAngle: .pi)
                : .identity
            self.layoutIfNeeded()
        }
    }

    private func updateBottomBar(selectedCount: Int) {
        previewBtn.isEnabled = selectedCount > 0
        if selectedCount > 0 {
            previewBtn.setTitle("预览 (\(selectedCount))", for: .normal)
        } else {
            previewBtn.setTitle("预览", for: .normal)
        }
        confirmBtn.alpha = selectedCount > 0 ? 1 : 0.55
    }

    @objc private func tapClose() { onClose?() }
    @objc private func tapAlbum() { onToggleAlbum?() }
    @objc private func tapPreview() { onPreview?() }
    @objc private func tapConfirm() { onConfirm?() }
    @objc private func hideLimitToast() { limitBanner.isHidden = true }
}

extension PhotoPickerView: UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        store.assets.count
    }

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! PhotoPickerCell
        let asset = store.assets[indexPath.item]
        let index = selectedIds.firstIndex(of: asset.localIdentifier)
        cell.configure(asset: asset, selectedIndex: index, store: store, size: thumbnailSize())
        return cell
    }

    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        onSelectAsset?(indexPath.item)
    }

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        thumbnailSize()
    }
}

private final class PhotoPickerCell: UICollectionViewCell {
    private let imageView = UIImageView()
    private let dimView = UIView()
    private let badge = UILabel()
    private var requestId: PHImageRequestID = PHInvalidImageRequestID
    private var assetId: String = ""

    override init(frame: CGRect) {
        super.init(frame: frame)
        imageView.contentMode = .scaleAspectFill
        imageView.clipsToBounds = true
        dimView.backgroundColor = UIColor.black.withAlphaComponent(0.28)
        dimView.isHidden = true
        badge.textAlignment = .center
        badge.font = .systemFont(ofSize: 13, weight: .semibold)
        badge.layer.cornerRadius = 11
        badge.clipsToBounds = true
        contentView.addSubview(imageView)
        contentView.addSubview(dimView)
        contentView.addSubview(badge)
        imageView.layoutChain.edges()
        dimView.layoutChain.edges()
        badge.layoutChain.top(5).right(5).width(22).height(22)
    }

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

    func configure(asset: PHAsset, selectedIndex: Int?, store: PhotoPickerStore, size: CGSize) {
        if requestId != PHInvalidImageRequestID {
            store.cancelRequest(requestId)
        }
        assetId = asset.localIdentifier
        imageView.image = nil
        let selected = selectedIndex != nil
        dimView.isHidden = !selected
        if let selectedIndex {
            badge.text = "\(selectedIndex + 1)"
            badge.textColor = .white
            badge.backgroundColor = UIColor(hexStr: "#007AFF")
            badge.layer.borderWidth = 0
        } else {
            badge.text = ""
            badge.backgroundColor = UIColor.black.withAlphaComponent(0.18)
            badge.layer.borderWidth = 1.5
            badge.layer.borderColor = UIColor.white.cgColor
        }
        requestId = store.requestThumbnail(for: asset, size: size) { [weak self] image in
            guard let self, self.assetId == asset.localIdentifier else { return }
            self.imageView.image = image
        }
    }

    override func prepareForReuse() {
        super.prepareForReuse()
        imageView.image = nil
        assetId = ""
    }
}