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

import Algorithms
import Foundation

public struct LineMap: Codable, Sendable {
	private let utf16LineOffsets: [Int]

	public init(source: String) {
		var offsets: [Int] = [0]
		for idx in source.indices {
			let c = source[idx]
			if c == "\n" || c == "\r\n" || c == "\r" {
				let next = source.index(after: idx)
				let utf16Offset = next.utf16Offset(in: source)
				offsets.append(utf16Offset)
			}
		}
		self.utf16LineOffsets = offsets
	}

	public func location(at utf16Offset: Int) -> (line: Int, column: Int) {
		let partitioningIndex = utf16LineOffsets.partitioningIndex { $0 > utf16Offset }
		let lineIndex = partitioningIndex == 0 ? 0 : partitioningIndex - 1
		let lineStart = utf16LineOffsets[lineIndex]
		let lineNumber = lineIndex
		let columnNumber = utf16Offset - lineStart
		return (lineNumber, columnNumber)
	}
}