using DataConnection.REST.Configuration;
using DataConnection.REST.Interfaces;
using DataConnection.REST.Models;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Net.Http.Json;
using System.Text.Json;
using System.Text.Json.Serialization;
using System.Threading;
using System.Threading.Tasks;

namespace DataConnection.REST.Implementations
{
    /// <summary>
    /// Client specific for Salesforce REST API.
    /// Handles OAuth2 authentication and metadata discovery.
    /// </summary>
    public class SalesforceServiceClient : BaseRestServiceClient, IRestMetadataDiscovery
    {
        private string? _accessToken;
        private string? _instanceUrl;
        private DateTime _tokenExpiry;

        public SalesforceServiceClient(HttpClient httpClient, RestServiceOptions options)
            : base(httpClient, options)
        {
        }

        /// <summary>
        /// Authenticates with Salesforce using Username/Password OAuth2 flow.
        /// </summary>
        /// <param name="clientId">Connected App Consumer Key</param>
        /// <param name="clientSecret">Connected App Consumer Secret</param>
        /// <param name="username">Salesforce username</param>
        /// <param name="password">Salesforce password + security token</param>
        /// <param name="cancellationToken">Cancellation token</param>
        /// <returns>True if authentication is successful</returns>
        public async Task<bool> AuthenticateAsync(string clientId, string clientSecret, string username, string password, CancellationToken cancellationToken = default)
        {
            try
            {
                var tokenEndpoint = "/services/oauth2/token";
                
                var tokenRequest = new List<KeyValuePair<string, string>>
                {
                    new("grant_type", "password"),
                    new("client_id", clientId),
                    new("client_secret", clientSecret),
                    new("username", username),
                    new("password", password)
                };

                var formContent = new FormUrlEncodedContent(tokenRequest);
                
                Console.WriteLine($"--- Salesforce Authentication Attempt ---");
                Console.WriteLine($"Target URL: {_httpClient.BaseAddress}{tokenEndpoint}");
                Console.WriteLine($"Username: {username}");
                Console.WriteLine($"--- End Salesforce Authentication Attempt ---");

                var response = await _httpClient.PostAsync(tokenEndpoint, formContent, cancellationToken);
                
                if (!response.IsSuccessStatusCode)
                {
                    var errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
                    Console.WriteLine($"Salesforce Authentication failed: {response.StatusCode}");
                    Console.WriteLine($"Error details: {errorContent}");
                    return false;
                }

                var tokenResponse = await response.Content.ReadFromJsonAsync<SalesforceTokenResponse>(cancellationToken: cancellationToken);
                  if (tokenResponse != null && !string.IsNullOrEmpty(tokenResponse.AccessToken))
                {
                    _accessToken = tokenResponse.AccessToken;
                    _instanceUrl = tokenResponse.InstanceUrl;
                    _tokenExpiry = DateTime.UtcNow.AddSeconds(3600); // Default 1 hour, Salesforce doesn't always return expires_in
                    
                    // Don't change BaseAddress - we'll use absolute URLs for API calls
                    // Store the instance URL for building complete URLs later
                    
                    // Add Authorization header for future requests
                    _httpClient.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", _accessToken);
                    
                    Console.WriteLine($"Salesforce Authentication successful. Token expires around: {_tokenExpiry.ToLocalTime()}");
                    Console.WriteLine($"Instance URL: {_instanceUrl}");
                    return true;
                }

                Console.WriteLine("Salesforce Authentication response could not be parsed.");
                return false;
            }
            catch (HttpRequestException ex)
            {
                Console.WriteLine($"HTTP Request Error during Salesforce Authentication: {ex.Message}");
                if (ex.InnerException != null)
                {
                    Console.WriteLine($"Inner Exception: {ex.InnerException.Message}");
                }
                return false;
            }
            catch (JsonException ex)
            {
                Console.WriteLine($"JSON Parsing Error during Salesforce Authentication: {ex.Message}");
                return false;
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error during Salesforce Authentication: {ex.Message}");
                return false;
            }
        }

        /// <summary>
        /// Checks if the current access token is active.
        /// </summary>
        public bool IsAuthenticated()
        {
            return !string.IsNullOrEmpty(_accessToken) && DateTime.UtcNow < _tokenExpiry;
        }

        /// <summary>
        /// Discovers SObjects (entities) and their fields from Salesforce.
        /// </summary>
        /// <param name="cancellationToken">Cancellation token</param>
        /// <returns>A list of discovered entity information</returns>
        public async Task<List<RestEntityInfo>> DiscoverEntitiesAsync(CancellationToken cancellationToken = default)
        {
            if (!IsAuthenticated())
            {
                Console.WriteLine("Error: Not authenticated to Salesforce. Cannot discover metadata.");
                return new List<RestEntityInfo>();
            }

            var entities = new List<RestEntityInfo>();
            try
            {
                // First, get list of all SObjects
                var sobjectsEndpoint = $"{_instanceUrl}/services/data/v60.0/sobjects/";
                var response = await _httpClient.GetAsync(sobjectsEndpoint, cancellationToken);
                response.EnsureSuccessStatusCode();

                var sobjectsResponse = await response.Content.ReadFromJsonAsync<SalesforceSObjectsResponse>(cancellationToken: cancellationToken);                if (sobjectsResponse?.SObjects != null)
                {
                    // For demo purposes, limit to first 20 objects to avoid too many API calls
                    var limitedSObjects = sobjectsResponse.SObjects.ToList();

                    // Process SObjects in parallel for better performance
                    var semaphore = new SemaphoreSlim(20, 20); // Limit concurrent requests to 5
                    var tasks = limitedSObjects.Where(sobject => !string.IsNullOrEmpty(sobject.Name))
                        .Select(async sobject =>
                        {
                            await semaphore.WaitAsync(cancellationToken);
                            try
                            {
                                // Get detailed field information for each SObject
                                var describeEndpoint = $"{_instanceUrl}/services/data/v60.0/sobjects/{sobject.Name}/describe/";
                                var describeResponse = await _httpClient.GetAsync(describeEndpoint, cancellationToken);

                                if (describeResponse.IsSuccessStatusCode)
                                {
                                    var describeResult = await describeResponse.Content.ReadFromJsonAsync<SalesforceDescribeResponse>(cancellationToken: cancellationToken);

                                    if (describeResult?.Fields != null)
                                    {
                                        var entityInfo = new RestEntityInfo
                                        {
                                            Name = sobject.Name
                                        };

                                        foreach (var field in describeResult.Fields)
                                        {
                                            if (string.IsNullOrEmpty(field.Name)) continue;

                                            var propInfo = new RestPropertyInfo
                                            {
                                                Name = field.Name,
                                                Type = field.Type ?? "string",
                                                IsKey = field.Name.Equals("Id", StringComparison.OrdinalIgnoreCase)
                                            };
                                            entityInfo.Properties.Add(propInfo);
                                        }

                                        return entityInfo;
                                    }
                                }
                                return null;
                            }
                            catch (Exception ex)
                            {
                                Console.WriteLine($"Error describing SObject {sobject.Name}: {ex.Message}");
                                return null;
                            }
                            finally
                            {
                                semaphore.Release();
                            }
                        });

                    var results = await Task.WhenAll(tasks);
                    entities.AddRange(results.Where(result => result != null)!);
                }
            }
            catch (HttpRequestException ex)
            {
                Console.WriteLine($"HTTP Request Error during Salesforce metadata discovery: {ex.Message}");
            }
            catch (JsonException ex)
            {
                Console.WriteLine($"JSON Parsing Error during Salesforce metadata discovery: {ex.Message}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error during Salesforce metadata discovery: {ex.Message}");
            }

            return entities;
        }

        /// <summary>
        /// Discovers a list of available SObjects from Salesforce without detailed field information.
        /// </summary>
        /// <param name="cancellationToken">Cancellation token</param>
        /// <returns>A list of discovered SObject summaries</returns>
        public async Task<List<RestEntitySummary>> DiscoverEntitySummariesAsync(CancellationToken cancellationToken = default)
        {
            if (!IsAuthenticated())
            {
                Console.WriteLine("Error: Not authenticated to Salesforce. Cannot discover metadata.");
                return new List<RestEntitySummary>();
            }

            var entities = new List<RestEntitySummary>();
            try
            {
                // Get list of all SObjects
                var sobjectsEndpoint = $"{_instanceUrl}/services/data/v60.0/sobjects/";
                var response = await _httpClient.GetAsync(sobjectsEndpoint, cancellationToken);
                response.EnsureSuccessStatusCode();

                var sobjectsResponse = await response.Content.ReadFromJsonAsync<SalesforceSObjectsResponse>(cancellationToken: cancellationToken);
                
                if (sobjectsResponse?.SObjects != null)
                {
                    foreach (var sobject in sobjectsResponse.SObjects)
                    {
                        if (string.IsNullOrEmpty(sobject.Name)) continue;

                        var entitySummary = new RestEntitySummary
                        {
                            Name = sobject.Name,
                            Label = sobject.Label ?? sobject.Name,
                            IsCustom = sobject.Custom,
                            EntityType = "SObject"
                        };
                        entities.Add(entitySummary);
                    }
                }
            }
            catch (HttpRequestException ex)
            {
                Console.WriteLine($"HTTP Request Error during Salesforce metadata discovery: {ex.Message}");
            }
            catch (JsonException ex)
            {
                Console.WriteLine($"JSON Parsing Error during Salesforce metadata discovery: {ex.Message}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error during Salesforce metadata discovery: {ex.Message}");
            }

            return entities.OrderBy(e => e.Name).ToList();
        }

        /// <summary>
        /// Discovers detailed information for a specific SObject including all its fields.
        /// </summary>
        /// <param name="entityName">The name of the SObject to get details for</param>
        /// <param name="cancellationToken">Cancellation token</param>
        /// <returns>Detailed SObject information or null if not found</returns>
        public async Task<RestEntityInfo?> DiscoverEntityDetailsAsync(string entityName, CancellationToken cancellationToken = default)
        {
            if (!IsAuthenticated())
            {
                Console.WriteLine("Error: Not authenticated to Salesforce. Cannot discover entity details.");
                return null;
            }

            try
            {
                // Get detailed field information for the specific SObject
                var describeEndpoint = $"{_instanceUrl}/services/data/v60.0/sobjects/{entityName}/describe/";
                var describeResponse = await _httpClient.GetAsync(describeEndpoint, cancellationToken);

                if (!describeResponse.IsSuccessStatusCode)
                {
                    Console.WriteLine($"Failed to get details for SObject {entityName}: {describeResponse.StatusCode}");
                    return null;
                }

                var describeResult = await describeResponse.Content.ReadFromJsonAsync<SalesforceDescribeResponse>(cancellationToken: cancellationToken);

                if (describeResult?.Fields != null)
                {
                    var entityInfo = new RestEntityInfo
                    {
                        Name = entityName
                    };

                    foreach (var field in describeResult.Fields)
                    {
                        if (string.IsNullOrEmpty(field.Name)) continue;

                        var propInfo = new RestPropertyInfo
                        {
                            Name = field.Name,
                            Type = field.Type ?? "string",
                            IsKey = field.Name.Equals("Id", StringComparison.OrdinalIgnoreCase),
                            IsRequired = !field.Nillable,
                            MaxLength = field.Length > 0 ? field.Length : null
                        };
                        entityInfo.Properties.Add(propInfo);
                    }

                    return entityInfo;
                }
            }
            catch (HttpRequestException ex)
            {
                Console.WriteLine($"HTTP Request Error during Salesforce entity details discovery: {ex.Message}");
            }
            catch (JsonException ex)
            {
                Console.WriteLine($"JSON Parsing Error during Salesforce entity details discovery: {ex.Message}");
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error during Salesforce entity details discovery: {ex.Message}");
            }

            return null;
        }

        /// <summary>
        /// Creates a new SObject in Salesforce.
        /// </summary>
        /// <param name="entityName">The name of the SObject to create (e.g., "Account", "Contact").</param>
        /// <param name="entityData">The data for the new SObject as key-value pairs.</param>
        /// <param name="cancellationToken">Cancellation token.</param>
        /// <returns>The created entity data or null if creation failed.</returns>
        public override async Task<Dictionary<string, object>?> CreateEntityAsync(string entityName, Dictionary<string, object> entityData, CancellationToken cancellationToken = default)
        {
            if (!IsAuthenticated())
            {
                Console.WriteLine("Error: Not authenticated to Salesforce. Cannot create entity.");
                return null;
            }            // Salesforce REST API endpoint for creating SObjects
            var createUri = $"{_instanceUrl}/services/data/v60.0/sobjects/{entityName}/";

            try
            {
                Console.WriteLine($"--- Salesforce Entity Creation Attempt ---");
                Console.WriteLine($"SObject: {entityName}");
                Console.WriteLine($"Target URL: {createUri}");
                Console.WriteLine($"Data: {System.Text.Json.JsonSerializer.Serialize(entityData)}");

                var response = await _httpClient.PostAsJsonAsync(createUri, entityData, cancellationToken);

                if (!response.IsSuccessStatusCode)
                {
                    var errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
                    Console.WriteLine($"Salesforce Entity Creation failed: {response.StatusCode}");
                    Console.WriteLine($"Error details: {errorContent}");
                    Console.WriteLine($"--- End Salesforce Entity Creation Attempt (Failed) ---");
                    return null;
                }

                var responseContent = await response.Content.ReadAsStringAsync(cancellationToken);
                Console.WriteLine($"Salesforce Entity Creation successful");
                Console.WriteLine($"Response: {responseContent}");
                Console.WriteLine($"--- End Salesforce Entity Creation Attempt (Success) ---");

                if (string.IsNullOrEmpty(responseContent))
                    return entityData; // Return original data if no response content

                // Salesforce returns creation result with Id and success status
                var creationResult = System.Text.Json.JsonSerializer.Deserialize<Dictionary<string, object>>(responseContent);
                
                // Merge the original data with the creation result (which includes the new Id)
                if (creationResult != null)
                {
                    var result = new Dictionary<string, object>(entityData);
                    foreach (var kvp in creationResult)
                    {
                        result[kvp.Key] = kvp.Value;
                    }
                    return result;
                }

                return creationResult;
            }
            catch (HttpRequestException ex)
            {
                Console.WriteLine($"HTTP Request Error during Salesforce entity creation: {ex.Message}");
                if (ex.InnerException != null)
                {
                    Console.WriteLine($"Inner Exception: {ex.InnerException.Message}");
                }
                Console.WriteLine($"--- End Salesforce Entity Creation Attempt (Exception) ---");
                return null;
            }
            catch (JsonException ex)
            {
                Console.WriteLine($"JSON Parsing Error during Salesforce entity creation: {ex.Message}");
                Console.WriteLine($"--- End Salesforce Entity Creation Attempt (JsonException) ---");
                return null;
            }
            catch (Exception ex)
            {
                Console.WriteLine($"Error during Salesforce entity creation: {ex.Message}");
                Console.WriteLine($"--- End Salesforce Entity Creation Attempt (Exception) ---");
                return null;
            }
        }

        // --- Nested classes for deserializing Salesforce responses ---
        private class SalesforceTokenResponse
        {
            [JsonPropertyName("access_token")]
            public string AccessToken { get; set; } = string.Empty;

            [JsonPropertyName("instance_url")]
            public string InstanceUrl { get; set; } = string.Empty;

            [JsonPropertyName("id")]
            public string Id { get; set; } = string.Empty;

            [JsonPropertyName("token_type")]
            public string TokenType { get; set; } = string.Empty;

            [JsonPropertyName("issued_at")]
            public string IssuedAt { get; set; } = string.Empty;

            [JsonPropertyName("signature")]
            public string Signature { get; set; } = string.Empty;
        }

        private class SalesforceSObjectsResponse
        {
            [JsonPropertyName("encoding")]
            public string Encoding { get; set; } = string.Empty;

            [JsonPropertyName("maxBatchSize")]
            public int MaxBatchSize { get; set; }

            [JsonPropertyName("sobjects")]
            public List<SalesforceSObject> SObjects { get; set; } = new List<SalesforceSObject>();
        }

        private class SalesforceSObject
        {
            [JsonPropertyName("name")]
            public string Name { get; set; } = string.Empty;

            [JsonPropertyName("label")]
            public string Label { get; set; } = string.Empty;

            [JsonPropertyName("custom")]
            public bool Custom { get; set; }

            [JsonPropertyName("keyPrefix")]
            public string KeyPrefix { get; set; } = string.Empty;
        }

        private class SalesforceDescribeResponse
        {
            [JsonPropertyName("name")]
            public string Name { get; set; } = string.Empty;

            [JsonPropertyName("label")]
            public string Label { get; set; } = string.Empty;

            [JsonPropertyName("fields")]
            public List<SalesforceField> Fields { get; set; } = new List<SalesforceField>();
        }

        private class SalesforceField
        {
            [JsonPropertyName("name")]
            public string Name { get; set; } = string.Empty;

            [JsonPropertyName("type")]
            public string Type { get; set; } = string.Empty;

            [JsonPropertyName("label")]
            public string Label { get; set; } = string.Empty;

            [JsonPropertyName("length")]
            public int Length { get; set; }

            [JsonPropertyName("nillable")]
            public bool Nillable { get; set; }

            [JsonPropertyName("unique")]
            public bool Unique { get; set; }
        }
    }
}