using System.Reflection;
using Connected.Configuration.Environment;
using Connected.Data.Schema;
using Connected.Entities;
using Connected.ServiceModel;
using Connected.ServiceModel.Transactions;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace Connected.Instance;

internal static class EntitySynchronizer
{
	public static async Task Synchronize(IServiceProvider services, string value)
	{
		var logger = services.GetService<ILogger<ServerStartup>>();

		if (logger is null)
			throw new NullReferenceException(nameof(ILogger<ServerStartup>));

		logger.LogTrace("Starting entities synchronization.");

		if (services.GetService<IContextProvider>() is not IContextProvider provider)
			throw new NullReferenceException(nameof(IContextProvider));

		using var ctx = provider.Create();

		if (ctx.GetService<IEnvironmentService>() is not IEnvironmentService environmentService)
			throw new NullReferenceException(nameof(IEnvironmentService));

		if (ctx.GetService<ISchemaService>() is not ISchemaService schemaService)
		{
			logger.LogWarning("ISchemaService is not registered. Entity synchronization skipped.");
			return;
		}
		/*
		 * entitySynchronization = rebuild
		 */
		if (string.Equals(value, "rebuild", StringComparison.OrdinalIgnoreCase))
		{
			logger.LogTrace("Rebuilding entities.");

			foreach (var assembly in environmentService.MicroServices)
				await Synchronize(schemaService, assembly, logger);
		}
		else
		{
			/*
			 * entitySynchronization = token1, token2,...
			 */
			var tokens = value.Split(',');
			/*
			 * token1: assembly : assemblyName
			 * token2: type : typeName
			 */
			foreach (var token in tokens)
			{
				var subTokens = token.Split(':');

				if (subTokens.Length != 2)
					throw new ArgumentException("Invalid entitySyncronization token '{token}'. Expected assembly:[assembly] or type:[type].", token);

				if (string.Equals(subTokens[0], "assembly", StringComparison.OrdinalIgnoreCase))
				{
					logger.LogTrace("Loading assembly '{assembly}'", subTokens[1]);

					await Synchronize(schemaService, Assembly.Load(AssemblyName.GetAssemblyName(subTokens[1])), logger);
				}
				else if (string.Equals(subTokens[1], "type", StringComparison.OrdinalIgnoreCase))
				{
					logger.LogTrace("Loading type '{type}'", subTokens[1]);

					if (Type.GetType(subTokens[1]) is not Type type)
					{
						logger.LogWarning("Entity type '{type}' could not be loaded. Synchronization on the specified type could not be performed.", subTokens[1]);
						continue;
					}

					await Synchronize(schemaService, new List<Type> { type });
				}
			}
		}

		logger.LogTrace("Commiting snchronization.");

		if (ctx.GetService<ITransactionContext>() is ITransactionContext transaction)
			await transaction.Commit();

		logger.LogTrace("Snchronization completed.");
	}

	private static async Task Synchronize(ISchemaService schemaService, Assembly assembly, ILogger<ServerStartup> logger)
	{
		var entities = new List<Type>();

		foreach (var type in assembly.GetTypes())
		{
			if (type.IsAbstract || !type.IsAssignableTo(typeof(IEntity)))
				continue;

			entities.Add(type);
		}

		if (entities.Any())
			await Synchronize(schemaService, entities);
	}

	private static async Task Synchronize(ISchemaService schemaService, List<Type> entities)
	{
		await schemaService.Synchronize(entities);
	}
}