JSONAPI/Tests/JSONAPITests/SparseFields/SparseFieldEncoderTests.swift

//
//  SparseFieldEncoderTests.swift
//  
//
//  Created by Mathew Polzin on 8/5/19.
//

import XCTest
@testable import JSONAPI
import Foundation

class SparseFieldEncoderTests: XCTestCase {
    func test_AccurateCodingPath() {
        let encoder = JSONEncoder()
        XCTAssertThrowsError(try encoder.encode(Wrapper()))

        do {
            let _ = try encoder.encode(Wrapper())
        } catch let err as Wrapper.OuterFail.FailError {
            XCTAssertEqual(err.path.first as? Wrapper.OuterFail.CodingKeys, Wrapper.OuterFail.CodingKeys.inner)
        } catch {
            XCTFail("received unexpected error during test")
        }
    }

    func test_SkipsOmittedFields() {
        let encoder = JSONEncoder()

        // does not throw because we omit the field that would have failed
        XCTAssertNoThrow(try encoder.encode(Wrapper(fields: [])))
    }

    func test_EverythingArsenal_allOn() {
        let encoder = JSONEncoder()

        let allThingsOn = try! encoder.encode(EverythingWrapper(fields: EverythingWrapper.EverythingWrapped.CodingKeys.allCases))

        let allThingsOnDeserialized = try! JSONSerialization.jsonObject(with: allThingsOn,
        options: []) as! [String: Any]

        XCTAssertNil(allThingsOnDeserialized["omittable"])
        XCTAssertNotNil(allThingsOnDeserialized["nullable"] as? NSNull)
        XCTAssertEqual(allThingsOnDeserialized["bool"] as? Bool, true)
        XCTAssertEqual(allThingsOnDeserialized["double"] as? Double, 10.5)
        XCTAssertEqual(allThingsOnDeserialized["string"] as? String, "hello")
        XCTAssertEqual(allThingsOnDeserialized["float"] as? Float, 1.2)
        XCTAssertEqual(allThingsOnDeserialized["int"] as? Int, 3)
        XCTAssertEqual(allThingsOnDeserialized["int8"] as? Int8, 4)
        XCTAssertEqual(allThingsOnDeserialized["int16"] as? Int16, 5)
        XCTAssertEqual(allThingsOnDeserialized["int32"] as? Int32, 6)
        XCTAssertEqual(allThingsOnDeserialized["int64"] as? Int64, 7)
        XCTAssertEqual(allThingsOnDeserialized["uint"] as? UInt, 8)
        XCTAssertEqual(allThingsOnDeserialized["uint8"] as? UInt8, 9)
        XCTAssertEqual(allThingsOnDeserialized["uint16"] as? UInt16, 10)
        XCTAssertEqual(allThingsOnDeserialized["uint32"] as? UInt32, 11)
        XCTAssertEqual(allThingsOnDeserialized["uint64"] as? UInt64, 12)
        XCTAssertEqual(allThingsOnDeserialized["nested"] as? String, "world")
    }

    func test_EverythingArsenal_allOff() {
        let encoder = JSONEncoder()

        let allThingsOn = try! encoder.encode(EverythingWrapper(fields: []))

        let allThingsOnDeserialized = try! JSONSerialization.jsonObject(with: allThingsOn,
                                                                        options: []) as! [String: Any]

        XCTAssertNil(allThingsOnDeserialized["omittable"])
        XCTAssertNil(allThingsOnDeserialized["nullable"])
        XCTAssertNil(allThingsOnDeserialized["bool"])
        XCTAssertNil(allThingsOnDeserialized["double"])
        XCTAssertNil(allThingsOnDeserialized["string"])
        XCTAssertNil(allThingsOnDeserialized["float"])
        XCTAssertNil(allThingsOnDeserialized["int"])
        XCTAssertNil(allThingsOnDeserialized["int8"])
        XCTAssertNil(allThingsOnDeserialized["int16"])
        XCTAssertNil(allThingsOnDeserialized["int32"])
        XCTAssertNil(allThingsOnDeserialized["int64"])
        XCTAssertNil(allThingsOnDeserialized["uint"])
        XCTAssertNil(allThingsOnDeserialized["uint8"])
        XCTAssertNil(allThingsOnDeserialized["uint16"])
        XCTAssertNil(allThingsOnDeserialized["uint32"])
        XCTAssertNil(allThingsOnDeserialized["uint64"])
        XCTAssertNil(allThingsOnDeserialized["nested"])
        XCTAssertEqual(allThingsOnDeserialized.count, 0)
    }

    func test_NilEncode() {
        let encoder = JSONEncoder()

        let nilOn = try! encoder.encode(NilWrapper(fields: [.hello]))
        let nilOff = try! encoder.encode(NilWrapper(fields: []))

        let nilOnDeserialized = try! JSONSerialization.jsonObject(with: nilOn,
                                                                  options: []) as! [String: Any]

        let nilOffDeserialized = try! JSONSerialization.jsonObject(with: nilOff,
                                                                   options: []) as! [String: Any]

        XCTAssertEqual(nilOnDeserialized.count, 1)
        XCTAssertNotNil(nilOnDeserialized["hello"] as? NSNull)
        XCTAssertEqual(nilOffDeserialized.count, 0)
    }

    func test_NestedContainers() {
        let encoder = JSONEncoder()

        let nestedOn = try! encoder.encode(NestedWrapper(fields: [.hello, .world]))
        let nestedOff = try! encoder.encode(NestedWrapper(fields: []))

        let nestedOnDeserialized = try! JSONSerialization.jsonObject(with: nestedOn,
                                                                     options: []) as! [String: Any]
        let nestedOffDeserialized = try! JSONSerialization.jsonObject(with: nestedOff,
                                                                      options: []) as! [String: Any]

        XCTAssertEqual(nestedOnDeserialized.count, 2)
        XCTAssertEqual((nestedOnDeserialized["hello"] as? [String: Bool])?["nestedKey"], true)
        XCTAssertEqual((nestedOnDeserialized["world"] as? [Bool])?.first, false)

        // NOTE: When a nested container is explicitly requested,
        //      the best we can do to omit the field is to encode
        //      nothing _within_ the nested container.
        XCTAssertEqual(nestedOffDeserialized.count, 2)
        // TODO: The container currently does not encode empty object
        //      for the keyed nested container but I think it should.
        XCTAssertEqual((nestedOffDeserialized["hello"] as? [String: Bool])?.count, 1)
        // TODO: The container currently does not encode empty array
        //      for the unkeyed nested container but I think it should.
        XCTAssertEqual((nestedOffDeserialized["world"] as? [Bool])?.count, 1)
    }

    func test_SuperEncoderIsStillSparse() {
        let encoder = JSONEncoder()

        let superOn = try! encoder.encode(SuperWrapper(fields: [.hello, .world]))
        let superOff = try! encoder.encode(SuperWrapper(fields: []))

        let superOnDeserialized = try! JSONSerialization.jsonObject(with: superOn,
                                                                     options: []) as! [String: Any]
        let superOffDeserialized = try! JSONSerialization.jsonObject(with: superOff,
                                                                      options: []) as! [String: Any]

        XCTAssertEqual(superOnDeserialized.count, 2)
        XCTAssertEqual((superOnDeserialized["hello"] as? [String: Bool])?["hello"], true)
        XCTAssertEqual((superOnDeserialized["super"] as? [String: Bool])?["world"], false)

        // NOTE: When explicitly requesting a super encoder
        //  the best we can do is tell the super encoder only
        //  to encode the same keys
        XCTAssertEqual(superOffDeserialized.count, 2)
        XCTAssertEqual((superOffDeserialized["hello"] as? [String: Bool])?.count, 0)
        XCTAssertEqual((superOffDeserialized["super"] as? [String: Bool])?.count, 0)
    }
}

extension SparseFieldEncoderTests {
    struct Wrapper: Encodable {

        let fields: [OuterFail.CodingKeys]

        init(fields: [OuterFail.CodingKeys] = OuterFail.CodingKeys.allCases) {
            self.fields = fields
        }

        func encode(to encoder: Encoder) throws {
            let sparseEncoder = SparseFieldEncoder(wrapping: encoder,
                                                   encoding: fields)
            try OuterFail(inner: .init()).encode(to: sparseEncoder)
        }

        struct OuterFail: Encodable {
            let inner: InnerFail

            public enum CodingKeys: String, Equatable, CaseIterable, CodingKey {
                case inner
            }

            struct InnerFail: Encodable {
                func encode(to encoder: Encoder) throws {

                    throw FailError(path: encoder.codingPath)
                }
            }

            struct FailError: Swift.Error {
                let path: [CodingKey]
            }
        }
    }

    struct EverythingWrapper: Encodable {
        let fields: [EverythingWrapped.CodingKeys]

        func encode(to encoder: Encoder) throws {
            let sparseEncoder = SparseFieldEncoder(wrapping: encoder,
                                                   encoding: fields)

            try EverythingWrapped(omittable: nil,
                                  nullable: .init(value: nil),
                                  bool: true,
                                  double: 10.5,
                                  string: "hello",
                                  float: 1.2,
                                  int: 3,
                                  int8: 4,
                                  int16: 5,
                                  int32: 6,
                                  int64: 7,
                                  uint: 8,
                                  uint8: 9,
                                  uint16: 10,
                                  uint32: 11,
                                  uint64: 12,
                                  nested: .init(value: "world"))
                .encode(to: sparseEncoder)
        }

        struct EverythingWrapped: Encodable {
            let omittable: Int?
            let nullable: Attribute<Int?>
            let bool: Bool
            let double: Double
            let string: String
            let float: Float
            let int: Int
            let int8: Int8
            let int16: Int16
            let int32: Int32
            let int64: Int64
            let uint: UInt
            let uint8: UInt8
            let uint16: UInt16
            let uint32: UInt32
            let uint64: UInt64
            let nested: Attribute<String>

            enum CodingKeys: String, Equatable, CaseIterable, CodingKey {
                case omittable
                case nullable
                case bool
                case double
                case string
                case float
                case int
                case int8
                case int16
                case int32
                case int64
                case uint
                case uint8
                case uint16
                case uint32
                case uint64
                case nested
            }
        }
    }

    struct NilWrapper: Encodable {
        let fields: [NilWrapped.CodingKeys]

        func encode(to encoder: Encoder) throws {
            let sparseEncoder = SparseFieldEncoder(wrapping: encoder,
                                                   encoding: fields)

            try NilWrapped()
                .encode(to: sparseEncoder)
        }

        struct NilWrapped: Encodable {
            func encode(to encoder: Encoder) throws {
                var container = encoder.container(keyedBy: CodingKeys.self)

                try container.encodeNil(forKey: .hello)
            }

            enum CodingKeys: String, Equatable, CodingKey {
                case hello
            }
        }
    }

    struct NestedWrapper: Encodable {
        let fields: [NestedWrapped.CodingKeys]

        func encode(to encoder: Encoder) throws {
            let sparseEncoder = SparseFieldEncoder(wrapping: encoder,
                                                   encoding: fields)

            try NestedWrapped()
                .encode(to: sparseEncoder)
        }

        struct NestedWrapped: Encodable {
            func encode(to encoder: Encoder) throws {
                var container = encoder.container(keyedBy: CodingKeys.self)

                var nestedContainer1 = container.nestedContainer(keyedBy: NestedKeys.self, forKey: .hello)

                var nestedContainer2 = container.nestedUnkeyedContainer(forKey: .world)

                try nestedContainer1.encode(true, forKey: .nestedKey)
                try nestedContainer2.encode(false)
            }

            enum CodingKeys: String, Equatable, CodingKey {
                case hello
                case world
            }

            enum NestedKeys: String, CodingKey {
                case nestedKey
            }
        }
    }

    struct SuperWrapper: Encodable {
        let fields: [SuperWrapped.CodingKeys]

        func encode(to encoder: Encoder) throws {
            let sparseEncoder = SparseFieldEncoder(wrapping: encoder,
                                                   encoding: fields)

            try SuperWrapped()
                .encode(to: sparseEncoder)
        }

        struct SuperWrapped: Encodable {
            func encode(to encoder: Encoder) throws {
                var container = encoder.container(keyedBy: CodingKeys.self)

                let superEncoder1 = container.superEncoder(forKey: .hello)

                let superEncoder2 = container.superEncoder()

                var container1 = superEncoder1.container(keyedBy: CodingKeys.self)
                var container2 = superEncoder2.container(keyedBy: CodingKeys.self)

                try container1.encode(true, forKey: .hello)
                try container2.encode(false, forKey: .world)
            }

            enum CodingKeys: String, Equatable, CodingKey {
                case hello
                case world
            }
        }
    }
}