import Foundation

class CacheObject: NSObject, NSCoding {
    var value: Any
    var expireDate: Date

    init(value: Any, expireDate: Date) {
        self.value = value
        self.expireDate = expireDate
    }

    required init?(coder aDecoder: NSCoder) {
        self.value = aDecoder.decodeObject(forKey: "value")!
        self.expireDate = aDecoder.decodeObject(forKey: "expiredDate") as! Date
    }

    func encode(with aCoder: NSCoder) {
        aCoder.encode(value, forKey: "value")
        aCoder.encode(expireDate, forKey: "expiredDate")
    }
}

class ArchiveCache {
    static let shared = ArchiveCache()
    private init() {
        let documentDirURL = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)
        cacheBaseURL = documentDirURL.appendingPathComponent("ArchiveCache")
        try! FileManager.default.createDirectory(at: cacheBaseURL, withIntermediateDirectories: true, attributes: nil)
    }

    private var memoryCache:[String: CacheObject] = [:]
    private var cacheBaseURL: URL

    func save(key: String, value: Any, seconds: Int) {
        let now = Date()
        let expireDate = now.addingTimeInterval(TimeInterval(seconds))

        // save it to memory cache
        let cacheObject = CacheObject(value: value, expireDate: expireDate)
        memoryCache[key] = cacheObject

        // save it to disk
        let cacheURL = cacheBaseURL.appendingPathComponent("\(key).plist")
        NSKeyedArchiver.archiveRootObject(cacheObject, toFile: cacheURL.path)
    }

    func get(key: String) -> Any? {
        let now = Date()

        // get memory cache
        if let memoryObject = memoryCache[key] {
            if now.timeIntervalSince(memoryObject.expireDate) > 0 {
                return nil
            } else {
                return memoryObject.value
            }
        }

        // get disk cache
        let cacheURL = cacheBaseURL.appendingPathComponent("\(key).plist")
        if let diskObject = NSKeyedUnarchiver.unarchiveObject(withFile: cacheURL.path) as? CacheObject {
            if now.timeIntervalSince(diskObject.expireDate) > 0 {
                return nil
            } else {
                return diskObject.value
            }
        }

        // nothing found
        return nil
    }
}