// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.IO;
using System.Text.Json;

namespace Microsoft.AspNetCore.Internal;

internal static class SystemTextJsonExtensions
{
    public static bool CheckRead(this ref Utf8JsonReader reader)
    {
        if (!reader.Read())
        {
            throw new InvalidDataException("Unexpected end when reading JSON.");
        }

        return true;
    }

    public static void EnsureObjectStart(this ref Utf8JsonReader reader)
    {
        if (reader.TokenType != JsonTokenType.StartObject)
        {
            throw new InvalidDataException($"Unexpected JSON Token Type '{reader.GetTokenString()}'. Expected a JSON Object.");
        }
    }

    public static string GetTokenString(this ref Utf8JsonReader reader)
    {
        return GetTokenString(reader.TokenType);
    }

    public static string GetTokenString(JsonTokenType tokenType)
    {
        switch (tokenType)
        {
            case JsonTokenType.None:
                break;
            case JsonTokenType.StartObject:
                return "Object";
            case JsonTokenType.StartArray:
                return "Array";
            case JsonTokenType.PropertyName:
                return "Property";
            default:
                break;
        }
        return tokenType.ToString();
    }

    public static void EnsureArrayStart(this ref Utf8JsonReader reader)
    {
        if (reader.TokenType != JsonTokenType.StartArray)
        {
            throw new InvalidDataException($"Unexpected JSON Token Type '{reader.GetTokenString()}'. Expected a JSON Array.");
        }
    }

    public static bool ReadAsBoolean(this ref Utf8JsonReader reader, string propertyName)
    {
        reader.Read();

        return reader.TokenType switch
        {
            JsonTokenType.False => false,
            JsonTokenType.True => true,
            _ => throw new InvalidDataException($"Expected '{propertyName}' to be true or false."),
        };
    }

    public static string ReadAsString(this ref Utf8JsonReader reader, string propertyName)
    {
        reader.Read();

        if (reader.TokenType != JsonTokenType.String)
        {
            throw new InvalidDataException($"Expected '{propertyName}' to be of type {JsonTokenType.String}.");
        }

        return reader.GetString()!;
    }

    public static int? ReadAsInt32(this ref Utf8JsonReader reader, string propertyName)
    {
        reader.Read();

        if (reader.TokenType == JsonTokenType.Null)
        {
            return null;
        }

        if (reader.TokenType != JsonTokenType.Number)
        {
            throw new InvalidDataException($"Expected '{propertyName}' to be of type {JsonTokenType.Number}.");
        }

        return reader.GetInt32();
    }

    public static long? ReadAsInt64(this ref Utf8JsonReader reader, string propertyName)
    {
        reader.Read();

        if (reader.TokenType == JsonTokenType.Null)
        {
            return null;
        }

        if (reader.TokenType != JsonTokenType.Number)
        {
            throw new InvalidDataException($"Expected '{propertyName}' to be of type {JsonTokenType.Number}.");
        }

        return reader.GetInt64();
    }
}