namespace Armada.Core.Database.SqlServer.Implementations
{
    using System;
    using System.Collections.Generic;
    using System.Threading;
    using System.Threading.Tasks;
    using Microsoft.Data.SqlClient;
    using SyslogLogging;
    using Armada.Core.Database.Interfaces;
    using Armada.Core.Enums;
    using Armada.Core.Models;
    using Armada.Core.Settings;

    /// <summary>
    /// SQL Server implementation of tenant database operations.
    /// </summary>
    public class TenantMethods : ITenantMethods
    {
        #region Private-Members

#pragma warning disable CS0414
        private readonly string _Header = "[TenantMethods] ";
#pragma warning restore CS0414
        private readonly SqlServerDatabaseDriver _Driver;
        private readonly DatabaseSettings _Settings;
        private readonly LoggingModule _Logging;

        #endregion

        #region Constructors-and-Factories

        /// <summary>
        /// Instantiate.
        /// </summary>
        /// <param name="driver">SQL Server database driver.</param>
        /// <param name="settings">Database settings.</param>
        /// <param name="logging">Logging module.</param>
        public TenantMethods(SqlServerDatabaseDriver driver, DatabaseSettings settings, LoggingModule logging)
        {
            _Driver = driver ?? throw new ArgumentNullException(nameof(driver));
            _Settings = settings ?? throw new ArgumentNullException(nameof(settings));
            _Logging = logging ?? throw new ArgumentNullException(nameof(logging));
        }

        #endregion

        #region Public-Methods

        /// <inheritdoc />
        public async Task<TenantMetadata> CreateAsync(TenantMetadata tenant, CancellationToken token = default)
        {
            if (tenant == null) throw new ArgumentNullException(nameof(tenant));
            tenant.LastUpdateUtc = DateTime.UtcNow;

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = @"INSERT INTO tenants (id, name, active, is_protected, created_utc, last_update_utc)
                            VALUES (@id, @name, @active, @is_protected, @created_utc, @last_update_utc);";
                    cmd.Parameters.AddWithValue("@id", tenant.Id);
                    cmd.Parameters.AddWithValue("@name", tenant.Name);
                    cmd.Parameters.AddWithValue("@active", tenant.Active);
                    cmd.Parameters.AddWithValue("@is_protected", tenant.IsProtected);
                    cmd.Parameters.AddWithValue("@created_utc", SqlServerDatabaseDriver.ToIso8601(tenant.CreatedUtc));
                    cmd.Parameters.AddWithValue("@last_update_utc", SqlServerDatabaseDriver.ToIso8601(tenant.LastUpdateUtc));
                    await cmd.ExecuteNonQueryAsync(token).ConfigureAwait(false);
                }
            }

            return tenant;
        }

        /// <inheritdoc />
        public async Task<TenantMetadata?> ReadAsync(string id, CancellationToken token = default)
        {
            if (string.IsNullOrEmpty(id)) throw new ArgumentNullException(nameof(id));

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "SELECT * FROM tenants WHERE id = @id;";
                    cmd.Parameters.AddWithValue("@id", id);
                    using (SqlDataReader reader = await cmd.ExecuteReaderAsync(token).ConfigureAwait(false))
                    {
                        if (await reader.ReadAsync(token).ConfigureAwait(false))
                            return SqlServerDatabaseDriver.TenantFromReader(reader);
                    }
                }
            }

            return null;
        }

        /// <inheritdoc />
        public async Task<TenantMetadata?> ReadByNameAsync(string name, CancellationToken token = default)
        {
            if (string.IsNullOrEmpty(name)) throw new ArgumentNullException(nameof(name));

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "SELECT * FROM tenants WHERE name = @name;";
                    cmd.Parameters.AddWithValue("@name", name);
                    using (SqlDataReader reader = await cmd.ExecuteReaderAsync(token).ConfigureAwait(false))
                    {
                        if (await reader.ReadAsync(token).ConfigureAwait(false))
                            return SqlServerDatabaseDriver.TenantFromReader(reader);
                    }
                }
            }

            return null;
        }

        /// <inheritdoc />
        public async Task<TenantMetadata> UpdateAsync(TenantMetadata tenant, CancellationToken token = default)
        {
            if (tenant == null) throw new ArgumentNullException(nameof(tenant));
            tenant.LastUpdateUtc = DateTime.UtcNow;

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = @"UPDATE tenants SET
                            name = @name,
                            active = @active,
                            is_protected = @is_protected,
                            last_update_utc = @last_update_utc
                            WHERE id = @id;";
                    cmd.Parameters.AddWithValue("@id", tenant.Id);
                    cmd.Parameters.AddWithValue("@name", tenant.Name);
                    cmd.Parameters.AddWithValue("@active", tenant.Active);
                    cmd.Parameters.AddWithValue("@is_protected", tenant.IsProtected);
                    cmd.Parameters.AddWithValue("@last_update_utc", SqlServerDatabaseDriver.ToIso8601(tenant.LastUpdateUtc));
                    await cmd.ExecuteNonQueryAsync(token).ConfigureAwait(false);
                }
            }

            return tenant;
        }

        /// <inheritdoc />
        public async Task DeleteAsync(string id, CancellationToken token = default)
        {
            if (string.IsNullOrEmpty(id)) throw new ArgumentNullException(nameof(id));

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "DELETE FROM tenants WHERE id = @id;";
                    cmd.Parameters.AddWithValue("@id", id);
                    await cmd.ExecuteNonQueryAsync(token).ConfigureAwait(false);
                }
            }
        }

        /// <inheritdoc />
        public async Task<List<TenantMetadata>> EnumerateAsync(CancellationToken token = default)
        {
            List<TenantMetadata> results = new List<TenantMetadata>();

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "SELECT * FROM tenants WHERE id != @system_id ORDER BY name;";
                    cmd.Parameters.AddWithValue("@system_id", "ten_system");
                    using (SqlDataReader reader = await cmd.ExecuteReaderAsync(token).ConfigureAwait(false))
                    {
                        while (await reader.ReadAsync(token).ConfigureAwait(false))
                            results.Add(SqlServerDatabaseDriver.TenantFromReader(reader));
                    }
                }
            }

            return results;
        }

        /// <inheritdoc />
        public async Task<EnumerationResult<TenantMetadata>> EnumerateAsync(EnumerationQuery query, CancellationToken token = default)
        {
            if (query == null) query = new EnumerationQuery();

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);

                List<string> conditions = new List<string>();
                List<SqlParameter> parameters = new List<SqlParameter>();

                conditions.Add("id != @system_id");
                parameters.Add(new SqlParameter("@system_id", "ten_system"));

                if (query.CreatedAfter.HasValue)
                {
                    conditions.Add("created_utc > @created_after");
                    parameters.Add(new SqlParameter("@created_after", SqlServerDatabaseDriver.ToIso8601(query.CreatedAfter.Value)));
                }
                if (query.CreatedBefore.HasValue)
                {
                    conditions.Add("created_utc < @created_before");
                    parameters.Add(new SqlParameter("@created_before", SqlServerDatabaseDriver.ToIso8601(query.CreatedBefore.Value)));
                }

                string whereClause = " WHERE " + string.Join(" AND ", conditions);
                string orderDirection = query.Order == EnumerationOrderEnum.CreatedAscending ? "ASC" : "DESC";

                // Count
                long totalCount = 0;
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "SELECT COUNT(*) FROM tenants" + whereClause + ";";
                    foreach (SqlParameter p in parameters) cmd.Parameters.Add(new SqlParameter(p.ParameterName, p.Value));
                    totalCount = Convert.ToInt64(await cmd.ExecuteScalarAsync(token).ConfigureAwait(false));
                }

                // Query
                List<TenantMetadata> results = new List<TenantMetadata>();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "SELECT * FROM tenants" + whereClause +
                        " ORDER BY created_utc " + orderDirection +
                        " OFFSET " + query.Offset + " ROWS FETCH NEXT " + query.PageSize + " ROWS ONLY;";
                    foreach (SqlParameter p in parameters) cmd.Parameters.Add(new SqlParameter(p.ParameterName, p.Value));
                    using (SqlDataReader reader = await cmd.ExecuteReaderAsync(token).ConfigureAwait(false))
                    {
                        while (await reader.ReadAsync(token).ConfigureAwait(false))
                            results.Add(SqlServerDatabaseDriver.TenantFromReader(reader));
                    }
                }

                return EnumerationResult<TenantMetadata>.Create(query, results, totalCount);
            }
        }

        /// <inheritdoc />
        public async Task<bool> ExistsAsync(string id, CancellationToken token = default)
        {
            if (string.IsNullOrEmpty(id)) throw new ArgumentNullException(nameof(id));

            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "SELECT COUNT(*) FROM tenants WHERE id = @id;";
                    cmd.Parameters.AddWithValue("@id", id);
                    int count = Convert.ToInt32(await cmd.ExecuteScalarAsync(token).ConfigureAwait(false));
                    return count > 0;
                }
            }
        }

        /// <inheritdoc />
        public async Task<bool> ExistsAnyAsync(CancellationToken token = default)
        {
            using (SqlConnection conn = new SqlConnection(_Driver.ConnectionString))
            {
                await conn.OpenAsync(token).ConfigureAwait(false);
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    cmd.CommandText = "SELECT COUNT(*) FROM tenants;";
                    int count = Convert.ToInt32(await cmd.ExecuteScalarAsync(token).ConfigureAwait(false));
                    return count > 0;
                }
            }
        }

        #endregion
    }
}

