CodableFirebase/CodableFirebase/FirebaseEncoder.swift

//
//  FirebaseEncoder.swift
//  CodableFirebase
//
//  Created by Oleksii on 27/12/2017.
//  Copyright © 2017 ViolentOctopus. All rights reserved.
//

import Foundation

open class FirebaseEncoder {
    /// The strategy to use for encoding `Date` values.
    public enum DateEncodingStrategy {
        /// Defer to `Date` for choosing an encoding. This is the default strategy.
        case deferredToDate
        
        /// Encode the `Date` as a UNIX timestamp (as a JSON number).
        case secondsSince1970
        
        /// Encode the `Date` as UNIX millisecond timestamp (as a JSON number).
        case millisecondsSince1970
        
        /// Encode the `Date` as an ISO-8601-formatted string (in RFC 3339 format).
        @available(OSX 10.12, iOS 10.0, watchOS 3.0, tvOS 10.0, *)
        case iso8601
        
        /// Encode the `Date` as a string formatted by the given formatter.
        case formatted(DateFormatter)
        
        /// Encode the `Date` as a custom value encoded by the given closure.
        ///
        /// If the closure fails to encode a value into the given encoder, the encoder will encode an empty automatic container in its place.
        case custom((Date, Encoder) throws -> Void)
    }
    
    /// The strategy to use for encoding `Data` values.
    public enum DataEncodingStrategy {
        /// Defer to `Data` for choosing an encoding.
        case deferredToData
        
        /// Encoded the `Data` as a Base64-encoded string. This is the default strategy.
        case base64
        
        /// Encode the `Data` as a custom value encoded by the given closure.
        ///
        /// If the closure fails to encode a value into the given encoder, the encoder will encode an empty automatic container in its place.
        case custom((Data, Encoder) throws -> Void)
    }
    
    public init() {}
    
    open var userInfo: [CodingUserInfoKey : Any] = [:]
    open var dateEncodingStrategy: DateEncodingStrategy = .deferredToDate
    open var dataEncodingStrategy: DataEncodingStrategy = .deferredToData
    
    open func encode<Value : Encodable>(_ value: Value) throws -> Any {
        let options = _FirebaseEncoder._Options(
            dateEncodingStrategy: dateEncodingStrategy,
            dataEncodingStrategy: dataEncodingStrategy,
            skipGeoPointAndReference: false,
            userInfo: userInfo
        )
        let encoder = _FirebaseEncoder(options: options)
        guard let topLevel = try encoder.box_(value) else {
            throw EncodingError.invalidValue(value,
                                             EncodingError.Context(codingPath: [],
                                                                   debugDescription: "Top-level \(Value.self) did not encode any values."))
        }
        
        return topLevel
    }
}