//  A simple segmented control with underline indicator for four tabs
import UIKit
import SnapKit

final class EPMessageSegmentView: UIView {
    enum Segment: Int, CaseIterable { case message=0, friend, following, fans }

    var titles: [String] = [
        YMLocalizedString("XPSessionMainViewController0"),
        YMLocalizedString("XPSessionMainViewController1"),
        YMLocalizedString("XPSessionMainViewController2"),
        YMLocalizedString("XPSessionMainViewController3")
    ]

    var didSelect: ((Int)->Void)?

    private var buttons: [UIButton] = []
    private let indicator = UIView()

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

    required init?(coder: NSCoder) { super.init(coder: coder); setup() }

    private func setup() {
        backgroundColor = .clear

        let stack = UIStackView()
        stack.axis = .horizontal
        stack.alignment = .fill
        stack.distribution = .fillEqually
        stack.spacing = 0
        addSubview(stack)
        stack.snp.makeConstraints { $0.edges.equalToSuperview() }

        for (idx, title) in titles.enumerated() {
            let b = UIButton(type: .custom)
            b.tag = idx
            b.setTitle(title, for: .normal)
            b.setTitleColor(UIColor.white.withAlphaComponent(0.6), for: .normal)
            b.setTitleColor(.white, for: .selected)
            b.titleLabel?.font = .systemFont(ofSize: 24, weight: idx == 0 ? .heavy : .regular)
            b.addTarget(self, action: #selector(onTap(_:)), for: .touchUpInside)
            buttons.append(b)
            stack.addArrangedSubview(b)
        }

        indicator.backgroundColor = UIColor.systemPink
        addSubview(indicator)
        layoutIfNeeded()
        select(index: 0, animated: false)
    }

    @objc private func onTap(_ sender: UIButton) {
        select(index: sender.tag, animated: true)
        didSelect?(sender.tag)
    }

    func select(index: Int, animated: Bool) {
        guard index >= 0 && index < buttons.count else { return }
        for (i,b) in buttons.enumerated() {
            b.isSelected = (i == index)
            b.titleLabel?.font = .systemFont(ofSize: 24, weight: b.isSelected ? .heavy : .regular)
        }
        let target = buttons[index]
        let width = target.bounds.width
        let y = bounds.height - 4
        let frame = CGRect(x: CGFloat(index) * width + width*0.15, y: y, width: width*0.7, height: 3)

        if animated {
            UIView.animate(withDuration: 0.2) {
                self.indicator.frame = frame
            }
        } else {
            indicator.frame = frame
        }
    }
}