// SPDX-FileCopyrightText: 2025 The Project Pterodactyl Developers
// SPDX-FileCopyrightText: 2026 The Project Pterodactyl Developers
//
// SPDX-License-Identifier: MPL-2.0

import Algorithms
import LanguageServerProtocol

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

	public init(source: String) {
		var offsets: [Int] = [0]
		for idx in source.indices {
			if source[idx].isNewline {
				let next = source.index(after: idx)
				let utf16Offset = next.utf16Offset(in: source)
				offsets.append(utf16Offset)
			}
		}

		self.utf16LineOffsets = offsets
	}

	public func lspPosition(at utf16Offset: Int) -> LanguageServerProtocol.Position {
		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 Position(line: lineNumber, character: columnNumber)
	}

	public func lspRange(of range: Range<Int>) -> LanguageServerProtocol.LSPRange {
		let start = lspPosition(at: range.lowerBound)
		let end = lspPosition(at: range.upperBound)
		return LSPRange(start: start, end: end)
	}

	public func range(from lspRange: LSPRange) -> Range<Int> {
		offset(at: lspRange.start)..<offset(at: lspRange.end)
	}

	public func offset(at position: LanguageServerProtocol.Position) -> Int {
		let lineOffset = utf16LineOffsets[position.line]
		return lineOffset + position.character
	}
}