using System;
using System.Collections.Generic;
using JetBrains.Annotations;
using UIWidgetsSample;
using Unity.UIWidgets.foundation;

namespace ChatComponents
{
    public enum MessageType
    {
        custom,
        file,
        image,
        text,
        unsupported
    }

    /// Extension with one [toShortString] method
    public class MessageTypeToShortString
    {
        /// Converts enum to the string equal to enum's name
        public MessageType messageType;

        private string toShortString()
        {
            return ToString().Split('.').last();
        }
    }

    /// All possible statuses message can have.
    public enum Status
    {
        delivered,
        error,
        seen,
        sending,
        sent
    }

    /// Extension with one [toShortString] method
    public class StatusToShortString
    {
        public Status status;

        /// Converts enum to the string equal to enum's name
        private string toShortString()
        {
            return ToString().Split('.').last();
        }
    }

    /// An abstract class that contains all variables and methods
    /// every message will have.
    public abstract class Message : Equatable
    {
        /// User who sent this message
        public readonly User author;

        /// Created message timestamp, in ms
        public readonly int? createdAt;

        /// Unique ID of the message
        public readonly string id;

        /// Additional custom metadata or attributes related to the message
        public readonly Dictionary<string, object> metadata;

        /// ID of the room where this message is sent
        public readonly string roomId;

        /// Message [Status]
        public readonly Status? status;

        /// [MessageType]
        public readonly MessageType type;

        public Message(
            User author,
            int? createdAt,
            string id,
            Dictionary<string, object> metadata,
            [CanBeNull] string roomId,
            Status? status,
            MessageType type
        )
        {
            this.author = author;
            this.createdAt = createdAt;
            this.id = id;
            this.metadata = metadata;
            this.roomId = roomId;
            this.status = status;
            this.type = type;
        }

        /// Creates a particular message from a map (decoded JSON).
        /// Type is determined by the `type` field.
        public static Message fromJson(Dictionary<string, object> json)
        {
            var type = json["type"] as string;

            switch (type)
            {
                case "custom":
                    return CustomMessage.fromJson(json);
                case "file":
                    return FileMessage.fromJson(json);
                case "image":
                    return ImageMessage.fromJson(json);
                case "text":
                    return TextMessage.fromJson(json);
                default:
                    return UnsupportedMessage.fromJson(json);
            }
        }

        /// Creates a copy of the message with an updated data
        /// [metadata] with null value will nullify existing metadata, otherwise
        /// both metadatas will be merged into one Map, where keys from a passed
        /// metadata will overwite keys from the previous one.
        /// [previewData] will be only set for the text message type.
        /// [status] with null value will be overwritten by the previous status.
        /// [text] will be only set for the text message type. Null value will be
        /// overwritten by the previous text (can't be empty).
        public abstract Message copyWith(
            Dictionary<string, object> metadata = null,
            [CanBeNull] PreviewData previewData = null,
            Status? status = default,
            string text = null
        );

        /// Converts a particular message to the map representation, encodable to JSON.\
        public abstract Dictionary<string, object> toJson();
    }
}