import SwiftSyntax
import SwiftSyntaxMacros
import SwiftCompilerPlugin

public struct ReadEnv: ExpressionMacro {
    public static func expansion(of node: some FreestandingMacroExpansionSyntax, in context: some MacroExpansionContext) throws -> ExprSyntax {
        guard let argument = node.arguments.first?.expression,
            let segments = argument.as(StringLiteralExprSyntax.self)?.segments,
            segments.count == 1,
            case .stringSegment(let literalSegment)? = segments.first
        else {
            throw CustomError.message("Need a static string")
        }

        let name = literalSegment.content.text
        return """
        ProcessInfo.processInfo.environment["\(raw: name)"]
        """
    }
}

enum CustomError: Error { case message(String) }

@main
struct NahiMacros: CompilerPlugin {
    var providingMacros: [Macro.Type] = [ReadEnv.self]
}