//
//  Copyright (c) 2020 Touch Instinct
//
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//
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//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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//

import Foundation

public protocol CodableKeyValueStorage {
    /// Returns the object with specified type associated with the first occurrence of the specified key.
    /// - Parameters:
    ///   - key: A key in the storage.
    ///   - decoder: CodableKeyValueDecoder to decode stored data.
    /// - Returns: The object with specified type associated with the specified key,
    /// or throw exception if the key was not found.
    /// - Throws: CodableStorageError
    func codableObject<Value: Decodable>(forKey key: StorageKey<Value>,
                                         decoder: CodableKeyValueDecoder) -> Result<Value, StorageError>

    /// Set or remove the value of the specified key in the storage.
    /// - Parameters:
    ///   - object: The object with specified type to store.
    ///   - key: The key with which to associate with the value.
    ///   - encoder: CodableKeyValueEncoder to encode to encode passed object.
    /// - Throws: EncodingError if error is occured during passed object encoding.
    func set<Value: Encodable>(encodableObject: Value,
                               forKey key: StorageKey<Value>,
                               encoder: CodableKeyValueEncoder) -> Result<Void, StorageError>

    /// Removes value for specific key
    /// - Parameter key: The key with which to associate with the value.
    /// - Throws: EncodingError if error is occured during reading/writing.
    func removeCodableValue<Value: Codable>(forKey key: StorageKey<Value>) -> Result<Void, StorageError>

    func hasCodableValue<Value: Decodable>(forKey key: StorageKey<Value>) -> Result<Bool, StorageError>
}

public extension CodableKeyValueStorage {

    /// Returns the object with specified type associated with the first occurrence of the specified key.
    /// - Parameters:
    ///   - key: A key in the storage.
    ///   - defaultValue: A default value that will be used if there is no such value for specified key,
    ///   - decoder: CodableKeyValueDecoder to decode stored data.
    /// or if error occurred during decoding
    /// - Returns: The object with specified type associated with the specified key, or passed default value
    /// if there is no such value for specified key or if error occurred during mapping.
    func codableObject<Value: Decodable>(forKey key: StorageKey<Value>,
                                         defaultValue: Value,
                                         decoder: CodableKeyValueDecoder = JSONKeyValueDecoder()) -> Value {

        (try? codableObject(forKey: key, decoder: decoder).get()) ?? defaultValue
    }

    func setOrRemove<Value: Codable>(codableObject: Value?,
                                     forKey key: StorageKey<Value>,
                                     encoder: CodableKeyValueEncoder = JSONKeyValueEncoder()) -> Result<Void, StorageError> {

        if let codableObject {
            return set(encodableObject: codableObject, forKey: key, encoder: encoder)
        } else {
            return removeCodableValue(forKey: key)
        }
    }

    subscript<Value: Codable>(key: StorageKey<Value>,
                              decoder: CodableKeyValueDecoder = JSONKeyValueDecoder(),
                              encoder: CodableKeyValueEncoder = JSONKeyValueEncoder()) -> Value? {

        get {
            try? codableObject(forKey: key, decoder: decoder).get()
        }
        set {
            try? setOrRemove(codableObject: newValue, forKey: key, encoder: encoder).get()
        }
    }
}