using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Graph;
using Microsoft.Identity.Client;
using Microsoft.Graph.Models;
using Microsoft.Kiota.Abstractions.Authentication;
using System.ComponentModel.Design;
using log4net;
using System.Threading;

namespace Epi2Exchange2
{
    internal class O365Connector
    {
        private static readonly ILog Logger = LogManager.GetLogger(typeof(O365Connector));
        private string clientID;
        private string clientSecret;
        private string tenantID;
        private string BaseUrl;

        public O365Connector(string clientID, string clientSecret, string tenantID, string BaseUrl)
        {
            this.clientID = clientID;
            this.clientSecret = clientSecret;
            this.tenantID = tenantID;
            this.BaseUrl = BaseUrl;
        }

        public async Task SyncContact(Contact contact, string destinationAccountPrimaryAddress)
        {
            try
            {
                var graphClient = await GetGraphClient();
                if (await DoesContactExist(contact, destinationAccountPrimaryAddress, graphClient))
                {
                    Logger.Info("Contact " + contact.DisplayName + " found in O365");
                    string O365ContactID = await GetContactIdByNickName(graphClient, destinationAccountPrimaryAddress, contact.NickName);

                    if (!string.IsNullOrEmpty(O365ContactID))
                    {
                        await graphClient.Users[destinationAccountPrimaryAddress]
                            .Contacts[O365ContactID]
                            .PatchAsync(contact);
                        Logger.Info($"Contact with ID '{O365ContactID}' successfully updated.");
                    }
                    else
                    {
                        Logger.Warn("No valid contact ID found for update.");
                    }
                }
                else
                {
                    Logger.Info("Contact " + contact.DisplayName + " NOT found in O365");
                    Logger.Info("Creating new Contact");
                    await graphClient.Users[destinationAccountPrimaryAddress].Contacts.PostAsync(contact);
                }
            }
            catch (Exception ex)
            {
                Logger.Error("Error while synchronizing contact: " + ex.Message);
            }
        }

        private async Task<string> GetContactIdByNickName(GraphServiceClient graphClient, string userPrimaryMail, string nickName)
        {
            try
            {
                var contacts = await graphClient.Users[userPrimaryMail]
                    .Contacts
                    .GetAsync(requestConfiguration =>
                    {
                        requestConfiguration.QueryParameters.Filter = $"NickName eq '{nickName}'";
                    });

                var contact = contacts?.Value?.FirstOrDefault();
                return contact?.Id;
            }
            catch (Exception ex)
            {
                Logger.Error($"Error retrieving contact with NickName '{nickName}': {ex.Message}");
                return null;
            }
        }

        private async Task<GraphServiceClient> GetGraphClient()
        {
            try
            {
                var clientApp = ConfidentialClientApplicationBuilder.Create(clientID)
                    .WithClientSecret(clientSecret)
                    .WithAuthority(new Uri($"{BaseUrl}/{tenantID}"))
                    .Build();

                var accessTokenProvider = new TokenAcquisitionProvider(clientApp);
                var authProvider = new BaseBearerTokenAuthenticationProvider(accessTokenProvider);

                return new GraphServiceClient(authProvider);
            }
            catch (Exception ex)
            {
                Logger.Error("Error initializing GraphServiceClient: " + ex.Message);
                throw;
            }
        }

        private async Task<bool> DoesContactExist(Contact contact, string userPrimaryMail, GraphServiceClient graphClient)
        {
            string NickName = contact.NickName;
            if (string.IsNullOrWhiteSpace(NickName))
            {
                Logger.Warn("No valid NickName found for the given contact.");
                return false;
            }

            try
            {
                var contacts = await graphClient.Users[userPrimaryMail]
                    .Contacts
                    .GetAsync(requestConfiguration =>
                    {
                        requestConfiguration.QueryParameters.Filter = $"NickName eq '{NickName}'";
                    });

                bool exists = contacts?.Value != null && contacts.Value.Any();
                Logger.Info($"Contact with NickName '{NickName}' exists: {exists}");
                return exists;
            }
            catch (Exception ex)
            {
                Logger.Error($"Error checking contacts: {ex.Message}");
                return false;
            }
        }
    }

    public class TokenAcquisitionProvider : IAccessTokenProvider
    {
        private readonly IConfidentialClientApplication _clientApp;

        public TokenAcquisitionProvider(IConfidentialClientApplication clientApp)
        {
            _clientApp = clientApp;
        }

        public async Task<string> GetAuthorizationTokenAsync(Uri uri, Dictionary<string, object> additionalAuthenticationContext = default, CancellationToken cancellationToken = default)
        {
            try
            {
                var result = await _clientApp.AcquireTokenForClient(new[] { "https://graph.microsoft.com/.default" })
                                             .ExecuteAsync(cancellationToken);
                return result.AccessToken;
            }
            catch (Exception ex)
            {
                Logger.Error("Error acquiring token: " + ex.Message);
                throw;
            }
        }

        public AllowedHostsValidator AllowedHostsValidator { get; } = new AllowedHostsValidator();
    }
}