import Foundation
import SourceKittenFramework

private var regexCache = [RegexCacheKey: NSRegularExpression]()
private let regexCacheLock = NSLock()

public struct RegularExpression: Hashable, Comparable, ExpressibleByStringLiteral {
    public let regex: NSRegularExpression

    public init(pattern: String, options: NSRegularExpression.Options? = nil) throws {
        regex = try .cached(pattern: pattern)
    }
    public init(stringLiteral value: String) {
        // swiftlint:disable:next force_try
        try! self.init(pattern: value)
    }

    var pattern: String { regex.pattern }

    var numberOfCaptureGroups: Int { regex.numberOfCaptureGroups }

    public static func < (lhs: Self, rhs: Self) -> Bool {
        lhs.pattern < rhs.pattern
    }
}

private struct RegexCacheKey: Hashable {
    let pattern: String
    let options: NSRegularExpression.Options

    func hash(into hasher: inout Hasher) {
        hasher.combine(pattern)
        hasher.combine(options.rawValue)
    }
}

extension NSRegularExpression: Comparable {
    public static func < (lhs: NSRegularExpression, rhs: NSRegularExpression) -> Bool {
        lhs.pattern < rhs.pattern
    }
}

public extension NSRegularExpression {
    static func cached(pattern: String, options: Options? = nil) throws -> NSRegularExpression {
        let options = options ?? [.anchorsMatchLines, .dotMatchesLineSeparators]
        let key = RegexCacheKey(pattern: pattern, options: options)
        regexCacheLock.lock()
        defer { regexCacheLock.unlock() }
        if let result = regexCache[key] {
            return result
        }

        let result = try NSRegularExpression(pattern: pattern, options: options)
        regexCache[key] = result
        return result
    }

    func matches(in stringView: StringView,
                 options: NSRegularExpression.MatchingOptions = []) -> [NSTextCheckingResult] {
        return matches(in: stringView.string, options: options, range: stringView.range)
    }

    func matches(in stringView: StringView,
                 options: NSRegularExpression.MatchingOptions = [],
                 range: NSRange) -> [NSTextCheckingResult] {
        return matches(in: stringView.string, options: options, range: range)
    }

    func matches(in file: SwiftLintFile,
                 options: NSRegularExpression.MatchingOptions = []) -> [NSTextCheckingResult] {
        return matches(in: file.stringView.string, options: options, range: file.stringView.range)
    }
}