using System;
using System.Collections.Generic;
using System.Configuration;
using Kreta.Core.MessageBroker.Azure.EventHub.Client.Configuration;

namespace Kreta.MessageBroker.Configuration
{
    /// <summary>
    /// Message client configuration section
    /// </summary>
    public class MessageBrokerConfigurationSection : ConfigurationSection, IMessageBrokerConfiguration, IAzureEventHubClientsConfiguration
    {
        /// <summary>
        /// Name of section
        /// </summary>
        const string SectionName = "MessageBroker";

        /// <summary>
        /// The instance
        /// </summary>
        static Lazy<MessageBrokerConfigurationSection> instance;

        /// <summary>
        /// Gets the instance.
        /// </summary>
        /// <value>
        /// The instance.
        /// </value>
        public static MessageBrokerConfigurationSection Instance
        {
            get
            {
                return instance.Value;
            }
        }

        /// <summary>
        /// Clients
        /// </summary>
        [ConfigurationProperty(nameof(Clients))]
        [ConfigurationCollection(typeof(MessageClientConfigurationElement))]
        public MessageClientConfigurationElementCollection Clients
        {
            get
            {
                return (MessageClientConfigurationElementCollection)base[nameof(Clients)];
            }
        }

        /// <summary>
        /// Clients
        /// </summary>
        [ConfigurationProperty(nameof(EventHubs))]
        [ConfigurationCollection(typeof(EventHubClientConfigurationElement))]
        public EventHubClientConfigurationElementCollection EventHubs
        {
            get
            {
                return (EventHubClientConfigurationElementCollection)base[nameof(EventHubs)];
            }
        }

        IEnumerable<IAzureEventHubClientConfiguration> IAzureEventHubClientsConfiguration.EventHubs => this.EventHubs;

        /// <summary>
        /// Initializes a new instance of the <see cref="MessageBrokerConfigurationSection"/> class.
        /// </summary>
        static MessageBrokerConfigurationSection()
        {
            instance = new Lazy<MessageBrokerConfigurationSection>(() =>
            {
                var section = (MessageBrokerConfigurationSection)ConfigurationManager.GetSection(SectionName);

                if (section == null)
                {
                    throw new ConfigurationErrorsException($"{SectionName} configuration section was not found");
                }

                return section;
            });
        }
    }
}