// <copyright file="OtelServiceNameEnvVarDetector.cs" company="OpenTelemetry Authors">
// Copyright The OpenTelemetry Authors
//
// Licensed 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>

#nullable enable

using System.Collections.Generic;
using Microsoft.Extensions.Configuration;
using OpenTelemetry.Internal;

namespace OpenTelemetry.Resources
{
    internal sealed class OtelServiceNameEnvVarDetector : IResourceDetector
    {
        public const string EnvVarKey = "OTEL_SERVICE_NAME";

        private readonly IConfiguration configuration;

        public OtelServiceNameEnvVarDetector(IConfiguration configuration)
        {
            this.configuration = configuration;
        }

        public Resource Detect()
        {
            var resource = Resource.Empty;

            if (this.configuration.TryGetStringValue(EnvVarKey, out string? envResourceAttributeValue))
            {
                resource = new Resource(new Dictionary<string, object>
                {
                    [ResourceSemanticConventions.AttributeServiceName] = envResourceAttributeValue!,
                });
            }

            return resource;
        }
    }
}
