DateEncodingTest.swift

import Foundation

struct Record: Codable {
    let id: String
    let updatedAt: Date
}

// Create a date with fractional seconds
let now = Date()
let record = Record(id: "test-123", updatedAt: now)

print("Original date: \(now)")
print("TimeInterval: \(now.timeIntervalSince1970)")
print()

// === Strategy 1: Standard .iso8601 (NO fractional seconds) ===
print("=== Strategy 1: .iso8601 (default, no fractions) ===")

let encoder1 = JSONEncoder()
encoder1.dateEncodingStrategy = .iso8601
encoder1.outputFormatting = .prettyPrinted

let decoder1 = JSONDecoder()
decoder1.dateDecodingStrategy = .iso8601

let json1 = try! encoder1.encode(record)
print("Encoded JSON:")
print(String(data: json1, encoding: .utf8)!)

let decoded1 = try! decoder1.decode(Record.self, from: json1)
print("\nDecoded date: \(decoded1.updatedAt)")
print("TimeInterval: \(decoded1.updatedAt.timeIntervalSince1970)")
print()

// === Strategy 2: Custom with fractional seconds ===
print("=== Strategy 2: Custom with fractional seconds ===")

let iso8601WithFractionalSeconds: ISO8601DateFormatter = {
    let formatter = ISO8601DateFormatter()
    formatter.formatOptions = [.withInternetDateTime, .withFractionalSeconds]
    return formatter
}()

let encoder2 = JSONEncoder()
encoder2.outputFormatting = .prettyPrinted
encoder2.dateEncodingStrategy = .custom { date, encoder in
    var container = encoder.singleValueContainer()
    let string = iso8601WithFractionalSeconds.string(from: date)
    try container.encode(string)
}

let decoder2 = JSONDecoder()
decoder2.dateDecodingStrategy = .custom { decoder in
    let container = try decoder.singleValueContainer()
    let string = try container.decode(String.self)
    if let date = iso8601WithFractionalSeconds.date(from: string) {
        return date
    }
    throw DecodingError.dataCorruptedError(in: container, debugDescription: "Invalid date: \(string)")
}

let json2 = try! encoder2.encode(record)
print("Encoded JSON:")
print(String(data: json2, encoding: .utf8)!)

let decoded2 = try! decoder2.decode(Record.self, from: json2)
print("\nDecoded date: \(decoded2.updatedAt)")
print("TimeInterval: \(decoded2.updatedAt.timeIntervalSince1970)")