import Foundation

extension String {

    var nonEmpty: String? {
        self.isEmpty ? nil : self
    }

    var trimmed: String {
        trimmingCharacters(in: .whitespacesAndNewlines)
    }

    func indented(by indentation: String) -> String {
        components(separatedBy: "\n").joined(separator: "\n" + indentation)
    }

    var withoutEmptyLines: String {
        components(separatedBy: "\n")
            .filter { !$0.trimmed.isEmpty }
            .joined(separator: "\n")
    }

    /**
     Remove the part after the last occurence of the separator (including the separator itself).

     The string is left unchanges, if it does not contain the separator.
     */
    func dropAfterLast(_ separator: String) -> String {
        guard contains(separator) else {
            return self
        }
        return components(separatedBy: separator).dropLast().joined(separator: separator)
    }

    func dropBeforeFirst(_ separator: String) -> String {
        guard contains(separator) else {
            return self
        }
        return components(separatedBy: separator).dropFirst().joined(separator: separator)
    }

    func lastComponentAfter(_ separator: String) -> String {
        components(separatedBy: separator).last!
    }

    /**
     Insert the new content before the last occurence of the specified separator.

     If the separator does not appear in the string, then the new content is simply appended.
     */
    func insert(_ content: String, beforeLast separator: String) -> String {
        let parts = components(separatedBy: separator)
        guard parts.count > 1 else {
            return self + content
        }
        return parts.dropLast().joined(separator: separator) + content + separator + parts.last!
    }

    func dropAfterFirst<T>(_ separator: T) -> String where T: StringProtocol {
        components(separatedBy: separator).first!
    }

    func between(_ start: String, and end: String) -> String {
        dropBeforeFirst(start).dropAfterFirst(end)
    }
}

extension Substring {

    func dropBeforeFirst(_ separator: String) -> String {
        guard contains(separator) else {
            return String(self)
        }
        return components(separatedBy: separator).dropFirst().joined(separator: separator)
    }

    func between(_ start: String, and end: String) -> String {
        components(separatedBy: start).last!
            .components(separatedBy: end).first!
    }

    func between(first: String, andLast last: String) -> String {
        dropBeforeFirst(first).dropAfterLast(last)
    }

    func last(after: String) -> String {
        components(separatedBy: after).last!
    }
}

extension String {

    func createFolderAndWrite(to url: URL) throws {
        try data(using: .utf8)!.createFolderAndWrite(to: url)
    }
}

extension String: DefaultValueProvider {

    static var defaultValue: String { "" }
}