/**
 *  Require
 *  Copyright (c) John Sundell 2017
 *  Licensed under the MIT license. See LICENSE file.
 */

import Foundation

public extension Optional {
    /**
     *  Require this optional to contain a non-nil value
     *
     *  This method will either return the value that this optional contains, or trigger
     *  a `preconditionFailure` with an error message containing debug information.
     *
     *  - parameter hint: Optionally pass a hint that will get included in any error
     *                    message generated in case nil was found.
     *
     *  - return: The value this optional contains.
     */
    func require(hint hintExpression: @autoclosure () -> String? = nil,
                 file: StaticString = #file,
                 line: UInt = #line) -> Wrapped {
        guard let unwrapped = self else {
            var message = "Required value was nil in \(file), at line \(line)"

            if let hint = hintExpression() {
                message.append(". Debugging hint: \(hint)")
            }

            #if !os(Linux)
            let exception = NSException(
                name: .invalidArgumentException,
                reason: message,
                userInfo: nil
            )

            exception.raise()
            #endif

            preconditionFailure(message)
        }

        return unwrapped
    }
}