//
//  Regex.swift
//  ha1fRegex
//
//  Created by はるふ on 2016/09/30.
//  Copyright © 2016年 はるふ. All rights reserved.
//

import Foundation

struct Regex {

    struct Match {
        var wholeString = ""
        var groups = [String]()

        init(wholeString: String, groups: [String]) {
            self.wholeString = wholeString
            self.groups = groups
        }

        init(text: NSString, result res: NSTextCheckingResult) {
            let components = (0..<res.numberOfRanges).map { text.substring(with: res.rangeAt($0)) }
            self.wholeString = components[0]
            self.groups = components.dropFirst().map { $0 }
        }
    }

    fileprivate let regex: NSRegularExpression

    init(_ pattern: String, options: NSRegularExpression.Options = []) throws {
        do {
            self.regex = try NSRegularExpression(pattern: pattern, options: options)
        }
    }

    func firstMatch(_ string: String, range: NSRange? = nil, options: NSRegularExpression.MatchingOptions = []) -> Match? {
        let targetRange = range ?? string.wholeNSRange()
        let nsstring = string as NSString
        if let res = self.regex.firstMatch(in: string, options: options, range: targetRange) {
            return Regex.Match(text: nsstring, result: res)
        } else {
            return nil
        }
    }

    func matches(_ string: String, range: NSRange? = nil, options: NSRegularExpression.MatchingOptions = []) -> [Match] {
        let targetRange = range ?? string.wholeNSRange()
        let nsstring = string as NSString
        return self.regex.matches(in: string, options: options, range: targetRange).map { res in
            return Regex.Match(text: nsstring, result: res)
        }
    }
}

extension String {
    fileprivate func wholeRange() -> Range<String.Index> {
        return Range(uncheckedBounds: (self.startIndex, self.endIndex))
    }

    fileprivate func wholeNSRange() -> NSRange {
        return NSRange(location: 0, length: self.characters.count)
    }

    func replace(_ regex: Regex, template: String, range: NSRange? = nil, options: NSRegularExpression.MatchingOptions = []) -> String {
        let targetRange = range ?? self.wholeNSRange()
        return regex.regex.stringByReplacingMatches(in: self, options: options, range: targetRange, withTemplate: template)
    }
}