using Salmon.Core;
using System.Diagnostics;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace Salmon.Web;

public class TripletJsonConverter
    : JsonConverter<Triplet>
{
    public override Triplet? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        Debug.Assert(reader.TokenType == JsonTokenType.StartObject);

        Triplet ret = new ();
        while (reader.Read())
        {
            if (reader.TokenType == JsonTokenType.EndObject)
                break;

            Debug.Assert(reader.TokenType == JsonTokenType.PropertyName);
            string jsonkey = reader.GetString();
            Debug.Assert(reader.Read());

            Debug.Assert(reader.TokenType != JsonTokenType.EndObject);
            Debug.Assert(reader.TokenType != JsonTokenType.EndArray);
            Debug.Assert(reader.TokenType != JsonTokenType.PropertyName);

            if(jsonkey.ToLower() == nameof(Triplet.key).ToLower())
            {
                Debug.Assert(reader.TokenType == JsonTokenType.String);
                ret.key = reader.GetString();
            }
            else if (jsonkey.ToLower() == nameof(Triplet.predicate).ToLower())
            {
                Debug.Assert(reader.TokenType == JsonTokenType.String);
                ret.predicate = reader.GetString();
            }
            else if(jsonkey.ToLower() == nameof(Triplet.LastFlush).ToLower())
            {
                Debug.Assert(reader.TokenType == JsonTokenType.String);
                ret.LastFlush = reader.GetDateTime();
            }
            else if (jsonkey.ToLower() == nameof(Triplet.value).ToLower())
            {
                if (reader.TokenType == JsonTokenType.Null)
                    ret.value = null;
                else if (reader.TokenType == JsonTokenType.False)
                    ret.value = false;
                else if (reader.TokenType == JsonTokenType.True)
                    ret.value = true;
                else if (reader.TokenType == JsonTokenType.String)
                    ret.value = reader.GetString();
                else if (reader.TokenType == JsonTokenType.Number)
                    ret.value = reader.GetDouble();
                else
                    throw new NotImplementedException($"Cannot read Triple.value from token type {reader.TokenType} at {reader.TokenStartIndex} for {reader.GetString()}.");
            }
            else
                Console.WriteLine($"Unknown triplet field {jsonkey} with token type {reader.TokenType}.");
        }

        return ret;

    }

    public override void Write(Utf8JsonWriter writer, Triplet value, JsonSerializerOptions options)
    {
        writer.WriteStartObject();
        
        writer.WriteString(nameof(Triplet.key), value.key);
        
        writer.WriteString(nameof(Triplet.predicate), value.predicate);
        
        writer.WritePropertyName(nameof(Triplet.LastFlush));
        writer.WriteStringValue(value.LastFlush);

        writer.WritePropertyName(nameof(Triplet.value));
        object? tval = value.value;
        if (tval is null)
            writer.WriteNullValue();
        else if (tval is bool)
            writer.WriteBooleanValue((bool)tval);
        else if (tval is string)
            writer.WriteStringValue((string)tval);
        else if (tval is int)
            writer.WriteNumberValue((int)tval);        
        else if (tval is long)
            writer.WriteNumberValue((long)tval);
        else if (tval is uint)
            writer.WriteNumberValue((uint)tval);
        else if (tval is ulong)
            writer.WriteNumberValue((ulong)tval);
        else if (tval is float)
            writer.WriteNumberValue((float)tval);
        else if (tval is double)
            writer.WriteNumberValue((double)tval);
        else if (tval is DateTime)
            writer.WriteStringValue((DateTime)tval);
        else
            throw new NotImplementedException($"Cannot serialize type {tval.GetType()}.");

        writer.WriteEndObject();
    }
}