import SwiftUI
import UIKit
import VorleserKit

struct BookTextView: UIViewRepresentable {
	let attributedText: NSAttributedString
	let highlightRange: Range<Int>?
	let onTapCharacter: (CharacterOffset) -> Void
	var scrollToOffset: CharacterOffset?

	func makeUIView(context: Context) -> UITextView {
		let textView = UITextView()
		textView.isEditable = false
		textView.isSelectable = false
		textView.textContainerInset = UIEdgeInsets(top: 16, left: 16, bottom: 16, right: 16)

		let tap = UITapGestureRecognizer(target: context.coordinator, action: #selector(Coordinator.handleTap(_:)))
		textView.addGestureRecognizer(tap)

		return textView
	}

	func updateUIView(_ textView: UITextView, context: Context) {
		let highlighted = NSMutableAttributedString(attributedString: attributedText)

		if let range = highlightRange,
		   range.lowerBound >= 0,
		   range.upperBound <= attributedText.length {
			let nsRange = NSRange(location: range.lowerBound, length: range.upperBound - range.lowerBound)
			highlighted.addAttribute(.backgroundColor, value: UIColor.systemYellow.withAlphaComponent(0.3), range: nsRange)
		}

		if textView.attributedText != highlighted {
			textView.attributedText = highlighted
		}

		if let range = highlightRange,
		   range.lowerBound >= 0,
		   range.upperBound <= attributedText.length {
			let nsRange = NSRange(location: range.lowerBound, length: range.upperBound - range.lowerBound)
			textView.scrollRangeToVisible(nsRange)
		}

		if let offset = scrollToOffset,
		   offset >= 0,
		   offset < attributedText.length {
			let nsRange = NSRange(location: offset, length: 1)
			textView.scrollRangeToVisible(nsRange)
		}
	}

	func makeCoordinator() -> Coordinator {
		Coordinator(onTapCharacter: onTapCharacter)
	}

	class Coordinator: NSObject {
		let onTapCharacter: (CharacterOffset) -> Void

		init(onTapCharacter: @escaping (CharacterOffset) -> Void) {
			self.onTapCharacter = onTapCharacter
		}

		@objc func handleTap(_ gesture: UITapGestureRecognizer) {
			guard let textView = gesture.view as? UITextView else { return }
			let point = gesture.location(in: textView)
			let characterIndex = textView.offset(
				from: textView.beginningOfDocument,
				to: textView.closestPosition(to: point) ?? textView.beginningOfDocument
			)
			if characterIndex < textView.attributedText.length {
				onTapCharacter(characterIndex)
			}
		}
	}
}