import Foundation

struct User: Codable {
    var username: String
    var email: String
}

struct Comment: Codable {
    var text: String
    var date: Date
    var user: User
}

struct BlogPost: Codable {
    var title: String
    var content: String
    var datePublished: Date
    var comments: [Comment]
    
    enum CodingKeys: String, CodingKey {
        case title
        case content
        case datePublished = "date_published"
        case comments
    }
    
    enum CommentCodingKeys: String, CodingKey {
        case text
        case date
        case user
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        title = try container.decode(String.self, forKey: .title)
        content = try container.decode(String.self, forKey: .content)
        datePublished = try container.decode(Date.self, forKey: .datePublished)
        
        var commentsContainer = try container.nestedUnkeyedContainer(forKey: .comments)
        var commentsArray: [Comment] = []
        while !commentsContainer.isAtEnd {
            let commentContainer = try commentsContainer.nestedContainer(keyedBy: CommentCodingKeys.self)
            let text = try commentContainer.decode(String.self, forKey: .text)
            let date = try commentContainer.decode(Date.self, forKey: .date)
            let user = try commentContainer.decode(User.self, forKey: .user)
            let comment = Comment(text: text, date: date, user: user)
            commentsArray.append(comment)
        }
        comments = commentsArray
    }
    
    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)
        try container.encode(title, forKey: .title)
        try container.encode(content, forKey: .content)
        try container.encode(datePublished, forKey: .datePublished)
        
        var commentsContainer = container.nestedUnkeyedContainer(forKey: .comments)
        for comment in comments {
            var commentContainer = commentsContainer.nestedContainer(keyedBy: CommentCodingKeys.self)
            try commentContainer.encode(comment.text, forKey: .text)
            try commentContainer.encode(comment.date, forKey: .date)
            try commentContainer.encode(comment.user, forKey: .user)
        }
    }
}

let json = """
{
    "title": "Sample Blog Post",
    "content": "This is the content of the blog post.",
    "date_published": "2023-10-06T08:00:00Z",
    "comments": [
        {
            "text": "Great post!",
            "date": "2023-10-06T10:00:00Z",
            "user": {
                "username": "user1",
                "email": "user1@example.com"
            }
        },
        {
            "text": "Thanks for sharing.",
            "date": "2023-10-06T11:00:00Z",
            "user": {
                "username": "user2",
                "email": "user2@example.com"
            }
        }
    ]
}
"""

let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .iso8601
decoder.keyDecodingStrategy = .convertFromSnakeCase

do {
    let blogPost = try decoder.decode(BlogPost.self, from: Data(json.utf8))
    print("Title: \(blogPost.title)")
    print("Content: \(blogPost.content)")
    print("Date Published: \(blogPost.datePublished)")
    print("Comments:")
    for comment in blogPost.comments {
        print("  Text: \(comment.text)")
        print("  Date: \(comment.date)")
        print("  User: \(comment.user.username) (\(comment.user.email))")
        print("-----")
    }
} catch {
    print("Error decoding JSON: \(error)")
}