dotnet/src/webdriver/Response.cs

// <copyright file="Response.cs" company="Selenium Committers">
// Licensed to the Software Freedom Conservancy (SFC) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The SFC licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.
// </copyright>

using OpenQA.Selenium.Internal;
using System;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Text.Json;
using System.Text.Json.Nodes;
using System.Text.Json.Serialization;

namespace OpenQA.Selenium;

/// <summary>
/// Handles responses from the browser
/// </summary>
public class Response
{
    /// <summary>
    /// Initializes a new instance of the <see cref="Response"/> class
    /// </summary>
    /// <param name="sessionId">The Session ID in use, if any.</param>
    /// <param name="value">The JSON payload of the response.</param>
    /// <param name="status">The WebDriver result status of the response.</param>
    public Response(string? sessionId, object? value, WebDriverResult status)
    {
        this.SessionId = sessionId;
        this.Value = value;
        this.Status = status;
    }

    /// <summary>
    /// Returns a new <see cref="Response"/> from a JSON-encoded string.
    /// </summary>
    /// <param name="value">The JSON string to deserialize into a <see cref="Response"/>.</param>
    /// <returns>A <see cref="Response"/> object described by the JSON string.</returns>
    /// <exception cref="ArgumentNullException">If <paramref name="value"/> is <see langword="null"/>.</exception>
    /// <exception cref="JsonException">If <paramref name="value"/> is not a valid JSON object.</exception>
    public static Response FromJson(string value)
    {
        JsonObject rawResponse = JsonNode.Parse(value) as JsonObject
            ?? throw new WebDriverException($"JSON success response did not return a dictionary{Environment.NewLine}{value}");

        JsonNode? contents;
        string? sessionId = null;

        if (rawResponse.TryGetPropertyValue("sessionId", out JsonNode? s) && s is not null)
        {
            sessionId = s.ToString();
        }

        if (rawResponse.TryGetPropertyValue("value", out JsonNode? valueObj))
        {
            contents = valueObj;
        }
        else
        {
            // If the returned object does *not* have a "value" property
            // the response value should be the entirety of the response.
            // TODO: Remove this if statement altogether; there should
            // never be a spec-compliant response that does not contain a
            // value property.

            // Special-case for the new session command, where the "capabilities"
            // property of the response is the actual value we're interested in.
            if (rawResponse.TryGetPropertyValue("capabilities", out JsonNode? capabilities))
            {
                contents = capabilities;
            }
            else
            {
                contents = rawResponse;
            }
        }

        if (contents is JsonObject valueDictionary)
        {
            // Special case code for the new session command. If the response contains
            // sessionId and capabilities properties, fix up the session ID and value members.
            if (valueDictionary.TryGetPropertyValue("sessionId", out JsonNode? session))
            {
                sessionId = session?.ToString();
                if (valueDictionary.TryGetPropertyValue("capabilities", out JsonNode? capabilities))
                {
                    contents = capabilities;
                }
                else
                {
                    contents = valueDictionary["value"];
                }
            }
        }

        var contentsDictionary = JsonSerializer.Deserialize(contents, ResponseJsonSerializerContext.Default.Object);

        return new Response(sessionId, contentsDictionary, WebDriverResult.Success);
    }

    /// <summary>
    /// Gets or sets the value from JSON.
    /// </summary>
    public object? Value { get; }

    /// <summary>
    /// Gets or sets the session ID.
    /// </summary>
    public string? SessionId { get; }

    /// <summary>
    /// Gets or sets the status value of the response.
    /// </summary>
    public WebDriverResult Status { get; }

    /// <summary>
    /// Returns a new <see cref="Response"/> from a JSON-encoded string.
    /// </summary>
    /// <param name="value">The JSON string to deserialize into a <see cref="Response"/>.</param>
    /// <returns>A <see cref="Response"/> object described by the JSON string.</returns>
    /// <exception cref="ArgumentNullException">If <paramref name="value"/> is <see langword="null"/>.</exception>
    /// <exception cref="JsonException">If <paramref name="value"/> is not a valid JSON object.</exception>
    /// <exception cref="WebDriverException">If the JSON dictionary is not in the expected state, per spec.</exception>
    public static Response FromErrorJson(string value)
    {
        JsonObject responseObject = JsonNode.Parse(value) as JsonObject
            ?? throw new WebDriverException($"JSON error response did not return an object{Environment.NewLine}{value}");

        if (!responseObject.TryGetPropertyValue("value", out JsonNode? valueNode))
        {
            throw new WebDriverException($"The 'value' property was not found in the response{Environment.NewLine}{value}");
        }

        if (valueNode is not JsonObject valueObject)
        {
            throw new WebDriverException($"The 'value' property is not a dictionary{Environment.NewLine}{value}");
        }

        if (!valueObject.TryGetPropertyValue("error", out JsonNode? errorObject))
        {
            throw new WebDriverException($"The 'value > error' property was not found in the response{Environment.NewLine}{value}");
        }

        if (errorObject is not JsonValue errorValue || !errorValue.TryGetValue(out string? errorString))
        {
            throw new WebDriverException($"The 'value > error' property is not a string{Environment.NewLine}{value}");
        }

        var valueDictionary = JsonSerializer.Deserialize(valueObject, ResponseJsonSerializerContext.Default.Object);
        WebDriverResult status = WebDriverError.ResultFromError(errorString);

        return new Response(sessionId: null, valueDictionary, status);
    }

    /// <summary>
    /// Returns this object as a JSON-encoded string.
    /// </summary>
    /// <returns>A JSON-encoded string representing this <see cref="Response"/> object.</returns>

    [RequiresUnreferencedCode("Untyped JSON serialization is not trim- or AOT- safe.")]
    [RequiresDynamicCode("Untyped JSON serialization is not trim- or AOT- safe.")]
    public string ToJson()
    {
        return JsonSerializer.Serialize(this);
    }

    /// <summary>
    /// Throws if <see cref="Value"/> is <see langword="null"/>.
    /// </summary>
    /// <exception cref="WebDriverException">If <see cref="Value"/> is <see langword="null"/>.</exception>
    [MemberNotNull(nameof(Value))]
    internal Response EnsureValueIsNotNull()
    {
        if (Value is null)
        {
            throw new WebDriverException("Response from remote end doesn't have $.Value property");
        }

        return this;
    }

    /// <summary>
    /// Returns the object as a string.
    /// </summary>
    /// <returns>A string with the Session ID, status value, and the value from JSON.</returns>
    public override string ToString()
    {
        return string.Format(CultureInfo.InvariantCulture, "({0} {1}: {2})", this.SessionId, this.Status, this.Value);
    }
}

[JsonSerializable(typeof(object))]
[JsonSourceGenerationOptions(Converters = [typeof(ResponseValueJsonConverter)])] // we still need it to make `Object` as `Dictionary`
internal sealed partial class ResponseJsonSerializerContext : JsonSerializerContext;