//
//  SettingsHeaderView.swift
//  MullvadVPN
//
//  Created by Jon Petersson on 2023-04-06.
//  Copyright © 2025 Mullvad VPN AB. All rights reserved.
//

import UIKit

class SettingsHeaderView: UITableViewHeaderFooterView {
    typealias InfoButtonHandler = () -> Void
    typealias CollapseHandler = (SettingsHeaderView) -> Void

    let titleLabel: UILabel = {
        let titleLabel = UILabel()
        titleLabel.translatesAutoresizingMaskIntoConstraints = false
        titleLabel.font = .mullvadSmallSemiBold
        titleLabel.adjustsFontForContentSizeCategory = true
        titleLabel.textColor = UIColor.Cell.titleTextColor
        titleLabel.numberOfLines = 0
        return titleLabel
    }()

    let infoButton: UIButton = {
        let button = UIButton(type: .custom)
        button.setAccessibilityIdentifier(.infoButton)
        button.adjustsImageSizeForAccessibilityContentSizeCategory = true
        button.tintColor = .white
        button.setImage(UIImage.Buttons.info, for: .normal)
        return button
    }()

    let collapseButton: UIButton = {
        let button = UIButton(type: .custom)
        button.adjustsImageSizeForAccessibilityContentSizeCategory = true
        button.setAccessibilityIdentifier(.expandButton)
        button.tintColor = .white
        return button
    }()

    var isExpanded = false {
        didSet {
            updateCollapseImage()
            updateAccessibilityCustomActions()
        }
    }

    var accessibilityCustomActionName = "" {
        didSet {
            updateAccessibilityCustomActions()
        }
    }

    var didCollapseHandler: CollapseHandler? {
        didSet {
            collapseButton.isHidden = didCollapseHandler == nil
        }
    }

    var infoButtonHandler: InfoButtonHandler? {
        didSet {
            infoButton.isHidden = infoButtonHandler == nil
        }
    }

    private let chevronDown = UIImage(named: "IconChevronDown")
    private let chevronUp = UIImage(named: "IconChevronUp")
    private let buttonWidth: CGFloat = 24

    override init(reuseIdentifier: String?) {
        super.init(reuseIdentifier: reuseIdentifier)

        infoButton.isHidden = true
        infoButton.addTarget(
            self,
            action: #selector(handleInfoButton(_:)),
            for: .touchUpInside
        )

        collapseButton.isHidden = true
        collapseButton.addTarget(
            self,
            action: #selector(handleCollapseButton(_:)),
            for: .touchUpInside
        )

        contentView.directionalLayoutMargins = UIMetrics.SettingsCell.defaultLayoutMargins
        contentView.backgroundColor = UIColor.Cell.Background.normal

        let buttonAreaWidth =
            UIMetrics.contentLayoutMargins.leading
            + UIMetrics
            .contentLayoutMargins.trailing + buttonWidth

        contentView.addConstrainedSubviews([titleLabel, infoButton, collapseButton]) {
            titleLabel.pinEdgesToSuperview(.init([.top(contentView.layoutMargins.top), .leading(16)]))
            titleLabel.bottomAnchor.constraint(
                equalTo: contentView.bottomAnchor,
                constant: -contentView.layoutMargins.bottom
            ).withPriority(.defaultHigh)

            infoButton.pinEdgesToSuperview(.init([.top(0), .bottom(0)]))
            titleLabel.trailingAnchor.constraint(
                equalTo: infoButton.leadingAnchor,
                constant: UIMetrics.TableView.infoButtonSpacing
            )
            infoButton.widthAnchor.constraint(equalToConstant: buttonAreaWidth)

            collapseButton.pinEdgesToSuperview(.all().excluding(.leading))
            collapseButton.leadingAnchor.constraint(greaterThanOrEqualTo: infoButton.trailingAnchor)
            collapseButton.widthAnchor.constraint(equalToConstant: buttonAreaWidth)
        }

        updateCollapseImage()
    }

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

    @objc private func handleInfoButton(_ sender: UIControl) {
        infoButtonHandler?()
    }

    @objc private func handleCollapseButton(_ sender: UIControl) {
        didCollapseHandler?(self)
    }

    @objc private func toggleCollapseAccessibilityAction() -> Bool {
        didCollapseHandler?(self)
        return true
    }

    private func updateCollapseImage() {
        let image = isExpanded ? chevronUp : chevronDown

        collapseButton.setImage(image, for: .normal)
        collapseButton.setAccessibilityIdentifier(isExpanded ? .collapseButton : .expandButton)
    }

    private func updateAccessibilityCustomActions() {
        let actionName =
            isExpanded
            ? String(format: NSLocalizedString("Collapse %@", comment: ""), accessibilityCustomActionName)
            : String(format: NSLocalizedString("Expand %@", comment: ""), accessibilityCustomActionName)

        accessibilityCustomActions = [
            UIAccessibilityCustomAction(
                name: actionName,
                target: self,
                selector: #selector(toggleCollapseAccessibilityAction)
            )
        ]
    }
}