using System.Text;
using System.Text.Json;

using AIStudio.Settings;
using AIStudio.Tools.ERIClient.DataModel;

namespace AIStudio.Tools.ERIClient;

public class ERIClientV1(string baseAddress) : ERIClientBase(baseAddress), IERIClient
{
    #region Implementation of IERIClient

    public async Task<APIResponse<List<AuthScheme>>> GetAuthMethodsAsync(CancellationToken cancellationToken = default)
    {
        using var response = await this.httpClient.GetAsync("/auth/methods", cancellationToken);
        if(!response.IsSuccessStatusCode)
        {
            return new()
            {
                Successful = false,
                Message = $"Failed to retrieve the authentication methods: there was an issue communicating with the ERI server. Code: {response.StatusCode}, Reason: {response.ReasonPhrase}"
            };
        }

        var authMethods = await response.Content.ReadFromJsonAsync<List<AuthScheme>>(JSON_OPTIONS, cancellationToken);
        if(authMethods is null)
        {
            return new()
            {
                Successful = false,
                Message = "Failed to retrieve the authentication methods: the ERI server did not return a valid response."
            };
        }

        return new()
        {
            Successful = true,
            Data = authMethods
        };
    }

    public async Task<APIResponse<AuthResponse>> AuthenticateAsync(IERIDataSource dataSource, RustService rustService, CancellationToken cancellationToken = default)
    {
        var authMethod = dataSource.AuthMethod;
        var username = dataSource.Username;
        switch (dataSource.AuthMethod)
        {
            case AuthMethod.NONE:
                using (var request = new HttpRequestMessage(HttpMethod.Post, $"auth?authMethod={authMethod}"))
                {
                    using var noneAuthResponse = await this.httpClient.SendAsync(request, cancellationToken);
                    if(!noneAuthResponse.IsSuccessStatusCode)
                    {
                        return new()
                        {
                            Successful = false,
                            Message = $"Failed to authenticate with the ERI server. Code: {noneAuthResponse.StatusCode}, Reason: {noneAuthResponse.ReasonPhrase}"
                        };
                    }
                    
                    var noneAuthResult = await noneAuthResponse.Content.ReadFromJsonAsync<AuthResponse>(JSON_OPTIONS, cancellationToken);
                    if(noneAuthResult == default)
                    {
                        return new()
                        {
                            Successful = false,
                            Message = "Failed to authenticate with the ERI server: the response was invalid."
                        };
                    }
                    
                    this.securityToken = noneAuthResult.Token ?? string.Empty;
                    return new()
                    {
                        Successful = true,
                        Data = noneAuthResult
                    };
                }
            
            case AuthMethod.USERNAME_PASSWORD:
                var passwordResponse = await rustService.GetSecret(dataSource);
                if (!passwordResponse.Success)
                {
                    return new()
                    {
                        Successful = false,
                        Message = "Failed to retrieve the password."
                    };
                }

                var password = await passwordResponse.Secret.Decrypt(Program.ENCRYPTION);
                using (var request = new HttpRequestMessage(HttpMethod.Post, $"auth?authMethod={authMethod}"))
                {
                    // We must send both values inside the header. The username field is named 'user'.
                    // The password field is named 'password'.
                    request.Headers.Add("user", username);
                    request.Headers.Add("password", password);

                    using var usernamePasswordAuthResponse = await this.httpClient.SendAsync(request, cancellationToken);
                    if(!usernamePasswordAuthResponse.IsSuccessStatusCode)
                    {
                        return new()
                        {
                            Successful = false,
                            Message = $"Failed to authenticate with the ERI server. Code: {usernamePasswordAuthResponse.StatusCode}, Reason: {usernamePasswordAuthResponse.ReasonPhrase}"
                        };
                    }
                    
                    var usernamePasswordAuthResult = await usernamePasswordAuthResponse.Content.ReadFromJsonAsync<AuthResponse>(JSON_OPTIONS, cancellationToken);
                    if(usernamePasswordAuthResult == default)
                    {
                        return new()
                        {
                            Successful = false,
                            Message = "Failed to authenticate with the server: the response was invalid."
                        };
                    }
                    
                    this.securityToken = usernamePasswordAuthResult.Token ?? string.Empty;
                    return new()
                    {
                        Successful = true,
                        Data = usernamePasswordAuthResult
                    };
                }

            case AuthMethod.TOKEN:
                var tokenResponse = await rustService.GetSecret(dataSource);
                if (!tokenResponse.Success)
                {
                    return new()
                    {
                        Successful = false,
                        Message = "Failed to retrieve the access token."
                    };
                }

                var token = await tokenResponse.Secret.Decrypt(Program.ENCRYPTION);
                using (var request = new HttpRequestMessage(HttpMethod.Post, $"auth?authMethod={authMethod}"))
                {
                    request.Headers.Add("Authorization", $"Bearer {token}");
                    
                    using var tokenAuthResponse = await this.httpClient.SendAsync(request, cancellationToken);
                    if(!tokenAuthResponse.IsSuccessStatusCode)
                    {
                        return new()
                        {
                            Successful = false,
                            Message = $"Failed to authenticate with the ERI server. Code: {tokenAuthResponse.StatusCode}, Reason: {tokenAuthResponse.ReasonPhrase}"
                        };
                    }
                    
                    var tokenAuthResult = await tokenAuthResponse.Content.ReadFromJsonAsync<AuthResponse>(JSON_OPTIONS, cancellationToken);
                    if(tokenAuthResult == default)
                    {
                        return new()
                        {
                            Successful = false,
                            Message = "Failed to authenticate with the ERI server: the response was invalid."
                        };
                    }
                    
                    this.securityToken = tokenAuthResult.Token ?? string.Empty;
                    return new()
                    {
                        Successful = true,
                        Data = tokenAuthResult
                    };
                }
                
            default:
                this.securityToken = string.Empty;
                return new()
                {
                    Successful = false,
                    Message = "The authentication method is not supported yet."
                };
        }
    }

    public async Task<APIResponse<DataSourceInfo>> GetDataSourceInfoAsync(CancellationToken cancellationToken = default)
    {
        using var request = new HttpRequestMessage(HttpMethod.Get, "/dataSource");
        request.Headers.Add("token", this.securityToken);
        
        using var response = await this.httpClient.SendAsync(request, cancellationToken);
        if(!response.IsSuccessStatusCode)
        {
            return new()
            {
                Successful = false,
                Message = $"Failed to retrieve the data source information: there was an issue communicating with the ERI server. Code: {response.StatusCode}, Reason: {response.ReasonPhrase}"
            };
        }
        
        var dataSourceInfo = await response.Content.ReadFromJsonAsync<DataSourceInfo>(JSON_OPTIONS, cancellationToken);
        if(dataSourceInfo == default)
        {
            return new()
            {
                Successful = false,
                Message = "Failed to retrieve the data source information: the ERI server did not return a valid response."
            };
        }
        
        return new()
        {
            Successful = true,
            Data = dataSourceInfo
        };
    }

    public async Task<APIResponse<List<EmbeddingInfo>>> GetEmbeddingInfoAsync(CancellationToken cancellationToken = default)
    {
        using var request = new HttpRequestMessage(HttpMethod.Get, "/embedding/info");
        request.Headers.Add("token", this.securityToken);
        
        using var response = await this.httpClient.SendAsync(request, cancellationToken);
        if(!response.IsSuccessStatusCode)
        {
            return new()
            {
                Successful = false,
                Message = $"Failed to retrieve the embedding information: there was an issue communicating with the ERI server. Code: {response.StatusCode}, Reason: {response.ReasonPhrase}"
            };
        }
        
        var embeddingInfo = await response.Content.ReadFromJsonAsync<List<EmbeddingInfo>>(JSON_OPTIONS, cancellationToken);
        if(embeddingInfo is null)
        {
            return new()
            {
                Successful = false,
                Message = "Failed to retrieve the embedding information: the ERI server did not return a valid response."
            };
        }
        
        return new()
        {
            Successful = true,
            Data = embeddingInfo
        };
    }

    public async Task<APIResponse<List<RetrievalInfo>>> GetRetrievalInfoAsync(CancellationToken cancellationToken = default)
    {
        using var request = new HttpRequestMessage(HttpMethod.Get, "/retrieval/info");
        request.Headers.Add("token", this.securityToken);
        
        using var response = await this.httpClient.SendAsync(request, cancellationToken);
        if(!response.IsSuccessStatusCode)
        {
            return new()
            {
                Successful = false,
                Message = $"Failed to retrieve the retrieval information: there was an issue communicating with the ERI server. Code: {response.StatusCode}, Reason: {response.ReasonPhrase}"
            };
        }
        
        var retrievalInfo = await response.Content.ReadFromJsonAsync<List<RetrievalInfo>>(JSON_OPTIONS, cancellationToken);
        if(retrievalInfo is null)
        {
            return new()
            {
                Successful = false,
                Message = "Failed to retrieve the retrieval information: the ERI server did not return a valid response."
            };
        }
        
        return new()
        {
            Successful = true,
            Data = retrievalInfo
        };
    }

    public async Task<APIResponse<List<Context>>> ExecuteRetrievalAsync(RetrievalRequest request, CancellationToken cancellationToken = default)
    {
        using var requestMessage = new HttpRequestMessage(HttpMethod.Post, "/retrieval");
        requestMessage.Headers.Add("token", this.securityToken);

        using var content = new StringContent(JsonSerializer.Serialize(request, JSON_OPTIONS), Encoding.UTF8, "application/json");
        requestMessage.Content = content;
        
        using var response = await this.httpClient.SendAsync(requestMessage, cancellationToken);
        if(!response.IsSuccessStatusCode)
        {
            return new()
            {
                Successful = false,
                Message = $"Failed to execute the retrieval request: there was an issue communicating with the ERI server. Code: {response.StatusCode}, Reason: {response.ReasonPhrase}"
            };
        }
        
        var contexts = await response.Content.ReadFromJsonAsync<List<Context>>(JSON_OPTIONS, cancellationToken);
        if(contexts is null)
        {
            return new()
            {
                Successful = false,
                Message = "Failed to execute the retrieval request: the ERI server did not return a valid response."
            };
        }
        
        return new()
        {
            Successful = true,
            Data = contexts
        };
    }

    public async Task<APIResponse<SecurityRequirements>> GetSecurityRequirementsAsync(CancellationToken cancellationToken = default)
    {
        using var request = new HttpRequestMessage(HttpMethod.Get, "/security/requirements");
        request.Headers.Add("token", this.securityToken);
        
        using var response = await this.httpClient.SendAsync(request, cancellationToken);
        if(!response.IsSuccessStatusCode)
        {
            return new()
            {
                Successful = false,
                Message = $"Failed to retrieve the security requirements: there was an issue communicating with the ERI server. Code: {response.StatusCode}, Reason: {response.ReasonPhrase}"
            };
        }
        
        var securityRequirements = await response.Content.ReadFromJsonAsync<SecurityRequirements>(JSON_OPTIONS, cancellationToken);
        if(securityRequirements == default)
        {
            return new()
            {
                Successful = false,
                Message = "Failed to retrieve the security requirements: the ERI server did not return a valid response."
            };
        }
        
        return new()
        {
            Successful = true,
            Data = securityRequirements
        };
    }

    #endregion
}