// Copyright Epic Games, Inc. All Rights Reserved.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

using EpicGames.Core;
using EpicGames.Perforce;
using Microsoft.Extensions.Logging;

using UnrealGameSync;
using UnrealGameSyncCmd.Options;
using UnrealGameSyncCmd.Utils;

using UserErrorException = UnrealGameSyncCmd.Exceptions.UserErrorException;

namespace UnrealGameSyncCmd.Commands
{
	internal class InitCommand : Command
	{
		public override async Task ExecuteAsync(CommandContext context)
		{
			ILogger logger = context.Logger;

			// Get the positional argument indicating the file to look for
			string? initName;
			context.Arguments.TryGetPositionalArgument(out initName);

			// Get the config settings from the command line
			InitCommandOptions options = new InitCommandOptions();
			context.Arguments.ApplyTo(options);
			context.Arguments.CheckAllArgumentsUsed();

			// Get the host name
			using IPerforceConnection perforce = await PerforceConnectionUtils.ConnectAsync(options.ServerAndPort, options.UserName, null, context.LoggerFactory);
			InfoRecord perforceInfo = await perforce.GetInfoAsync(InfoOptions.ShortOutput);
			string hostName = perforceInfo.ClientHost ?? Dns.GetHostName();

			// Create the perforce connection
			if (initName != null)
			{
				await InitNewClientAsync(perforce, initName, hostName, options, context.GlobalSettings, logger);
			}
			else
			{
				await InitExistingClientAsync(perforce, hostName, options, context.GlobalSettings, logger);
			}
		}

		static async Task InitNewClientAsync(IPerforceConnection perforce, string streamName, string hostName, InitCommandOptions options, UserSettings? globalSettings, ILogger logger)
		{
			logger.LogInformation("Checking stream...");

			// Get the given stream
			PerforceResponse<StreamRecord> streamResponse = await perforce.TryGetStreamAsync(streamName, true);
			if (!streamResponse.Succeeded)
			{
				throw new UserErrorException($"Unable to find stream '{streamName}'");
			}
			StreamRecord stream = streamResponse.Data;

			// Get the new directory for the client
			DirectoryReference clientDir = DirectoryReference.FromString(options.ClientRoot) ?? DirectoryReference.Combine(DirectoryReference.GetCurrentDirectory(), stream.Stream.Replace('/', '+'));
			DirectoryReference.CreateDirectory(clientDir);

			// Make up a new client name 
			string clientName = options.ClientName ?? Regex.Replace($"{perforce.Settings.UserName}_{hostName}_{stream.Stream.Trim('/')}", "[^0-9a-zA-Z_.-]", "+");

			if (!options.IgnoreExistingClients)
			{
				// Check there are no existing clients under the current path
				List<ClientsRecord> clients = await FindExistingClients(perforce, hostName, clientDir);
				if (clients.Count > 0)
				{
					if (clients.Count == 1 && clientName.Equals(clients[0].Name, StringComparison.OrdinalIgnoreCase) && clientDir == TryParseRoot(clients[0].Root))
					{
						logger.LogInformation("Reusing existing client for {ClientDir} ({ClientName})", clientDir, options.ClientName);
					}
					else
					{
						throw new UserErrorException("Current directory is already within a Perforce workspace ({ClientName})", clients[0].Name);
					}
				}
			}

			// Create the new client
			ClientRecord client = new ClientRecord(clientName, perforce.Settings.UserName, clientDir.FullName);
			client.Host = hostName;
			client.Stream = stream.Stream;
			client.Options = ClientOptions.Rmdir;
			await perforce.CreateClientAsync(client);

			// Branch root is currently hard-coded at the root
			string branchPath = options.BranchPath ?? String.Empty;
			string projectPath = await ProjectUtils.FindProjectPathAsync(perforce, clientName, branchPath, options.ProjectName);

			// Create the settings object
			UserWorkspaceSettings settings = new UserWorkspaceSettings();
			settings.RootDir = clientDir;
			settings.Init(perforce.Settings.ServerAndPort, perforce.Settings.UserName, clientName, branchPath, projectPath);
			options.ApplyTo(settings);
			settings.Save(logger);

			if (globalSettings != null)
			{
				UserSelectedProjectSettings selectedProjectSettings =
					new UserSelectedProjectSettings(
						null,
						null,
						UserSelectedProjectType.Client,
						$"//{client.Name}{projectPath}",
						$"{client.Root}{projectPath}".Replace("/", @"\", StringComparison.Ordinal));
				globalSettings.OpenProjects.Add(selectedProjectSettings);
				globalSettings.RecentProjects.Add(selectedProjectSettings);
				globalSettings.Save(logger);
			}

			logger.LogInformation("Initialized {ClientName} with root at {RootDir}", clientName, clientDir);
		}

		static DirectoryReference? TryParseRoot(string root)
		{
			try
			{
				return new DirectoryReference(root);
			}
			catch
			{
				return null;
			}
		}

		static async Task InitExistingClientAsync(IPerforceConnection perforce, string hostName, InitCommandOptions options, UserSettings? globalSettings, ILogger logger)
		{
			DirectoryReference currentDir = DirectoryReference.GetCurrentDirectory();

			// Make sure the client name is set
			string? clientName = options.ClientName;
			if (clientName == null)
			{
				List<ClientsRecord> clients = await FindExistingClients(perforce, hostName, currentDir);
				if (clients.Count == 0)
				{
					throw new UserErrorException("Unable to find client for {HostName} under {ClientDir}", hostName, currentDir);
				}
				if (clients.Count > 1)
				{
					throw new UserErrorException("Multiple clients found for {HostName} under {ClientDir}: {ClientList}", hostName, currentDir, String.Join(", ", clients.Select(x => x.Name)));
				}

				clientName = clients[0].Name;
				logger.LogInformation("Found client {ClientName}", clientName);
			}

			// Get the client info
			ClientRecord client = await perforce.GetClientAsync(clientName);
			DirectoryReference clientDir = new DirectoryReference(client.Root);

			// If a project path was specified in local syntax, try to convert it to client-relative syntax
			string? projectName = options.ProjectName;
			if (options.ProjectName != null && options.ProjectName.Contains('.', StringComparison.Ordinal))
			{
				options.ProjectName = FileReference.Combine(currentDir, options.ProjectName).MakeRelativeTo(clientDir).Replace('\\', '/');
			}

			// Branch root is currently hard-coded at the root
			string branchPath = options.BranchPath ?? String.Empty;
			string projectPath = await ProjectUtils.FindProjectPathAsync(perforce, clientName, branchPath, projectName);

			// Create the settings object
			UserWorkspaceSettings settings = new UserWorkspaceSettings();
			settings.RootDir = clientDir;
			settings.Init(perforce.Settings.ServerAndPort, perforce.Settings.UserName, clientName, branchPath, projectPath);
			options.ApplyTo(settings);
			settings.Save(logger);

			if (globalSettings != null)
			{
				UserSelectedProjectSettings selectedProjectSettings =
					new UserSelectedProjectSettings(
						null,
						null,
						UserSelectedProjectType.Client,
						$"//{client.Name}{projectPath}",
						$"{client.Root}{projectPath}".Replace("/", @"\", StringComparison.Ordinal));
				globalSettings.OpenProjects.Add(selectedProjectSettings);
				globalSettings.RecentProjects.Add(selectedProjectSettings);
				globalSettings.Save(logger);
			}

			logger.LogInformation("Initialized workspace at {RootDir} for {ClientProject}", clientDir, settings.ClientProjectPath);
		}

		static async Task<List<ClientsRecord>> FindExistingClients(IPerforceConnection perforce, string hostName, DirectoryReference clientDir)
		{
			List<ClientsRecord> matchingClients = new List<ClientsRecord>();

			List<ClientsRecord> clients = await perforce.GetClientsAsync(ClientsOptions.None, perforce.Settings.UserName);
			foreach (ClientsRecord client in clients)
			{
				if (!String.IsNullOrEmpty(client.Root) && !String.IsNullOrEmpty(client.Host) && String.Equals(hostName, client.Host, StringComparison.OrdinalIgnoreCase))
				{
					DirectoryReference? rootDir;
					try
					{
						rootDir = new DirectoryReference(client.Root);
					}
					catch
					{
						rootDir = null;
					}

					if (rootDir != null && clientDir.IsUnderDirectory(rootDir))
					{
						matchingClients.Add(client);
					}
				}
			}

			return matchingClients;
		}
	}
}