// SPDX-FileCopyrightText: 2025 The Project Pterodactyl Developers
//
// SPDX-License-Identifier: MPL-2.0

import Foundation
import LanguageServerProtocol

private enum ArraySymmetry {
	case identity
	case reverse
}

fileprivate extension Array {
	func apply(symmetry: ArraySymmetry) -> any Collection<Element> {
		switch symmetry {
		case .identity: self
		case .reverse: reversed()
		}
	}
}

extension SyntaxCursor {
	private func firstVisibleNode(under symmetry: ArraySymmetry) -> SyntaxCursor? {
		switch node {
		case .token(let token, _):
			return token.kind.isVisible ? self : nil
		case .tree:
			for child in children.apply(symmetry: symmetry) {
				if let visibleChild = child.firstVisibleNode(under: symmetry) { return visibleChild }
			}

			return nil
		}
	}

	private var visibleUtf16Range: Range<Int>? {
		guard
			let firstNode = firstVisibleNode(under: .identity),
			let lastNode = firstVisibleNode(under: .reverse)
		else { return nil }
		return firstNode.utf16Range.lowerBound..<lastNode.utf16Range.upperBound
	}

	private func collectFoldingRanges(_ sink: inout [FoldingRange]) {
		if let foldingRangeKind = node.tree?.metadata?.delimitedFoldingRangeKind, let visibleUtf16Range {
			let startLocation = lineMap.location(at: visibleUtf16Range.lowerBound)
			let endLocation = lineMap.location(at: visibleUtf16Range.upperBound)
			let foldingRange = FoldingRange(startLine: startLocation.line, endLine: endLocation.line, kind: foldingRangeKind)
			sink.append(foldingRange)
		}

		for child in children {
			child.collectFoldingRanges(&sink)
		}
	}

	public var foldingRanges: [FoldingRange] {
		var sink: [FoldingRange] = []
		collectFoldingRanges(&sink)
		return sink
	}
}