using MySql.Data.MySqlClient;
using System;
using System.Collections.Generic;
using System.Linq;

namespace HanvonF710XAttendanceService
{
    internal sealed class AttendanceMachineFaceTemplateDAO
    {
        public bool ExistsBySerialNo(MySqlConnection connection, string serialNo)
        {
            const string checkQuery = "SELECT COUNT(*) FROM attendance_machine_face_templates WHERE serial_no = @SerialNumber";
            using (var cmd = new MySqlCommand(checkQuery, connection))
            {
                cmd.Parameters.AddWithValue("@SerialNumber", serialNo);
                object result = cmd.ExecuteScalar();
                if (result == null || result == DBNull.Value)
                {
                    return false;
                }

                if (int.TryParse(result.ToString(), out int count))
                {
                    return count > 0;
                }

                return false;
            }
        }

        public int InsertTemplate(MySqlConnection connection, string serialNo, byte[] templateBytes, DateTime createdDate)
        {
            const string insertQuery =
                "INSERT INTO attendance_machine_face_templates (serial_no, template, created_date) " +
                "VALUES (@SerialNumber, @FaceTemplate, @created_date)";

            using (var cmd = new MySqlCommand(insertQuery, connection))
            {
                cmd.Parameters.AddWithValue("@SerialNumber", serialNo);
                cmd.Parameters.Add("@FaceTemplate", MySqlDbType.Blob).Value = templateBytes ?? Array.Empty<byte>();
                cmd.Parameters.AddWithValue("@created_date", createdDate);
                return cmd.ExecuteNonQuery();
            }
        }

        public Dictionary<string, byte[]> GetActiveTemplatesBySerialNos(MySqlConnection connection, IReadOnlyList<string> serialNos)
        {
            var result = new Dictionary<string, byte[]>(StringComparer.OrdinalIgnoreCase);
            if (serialNos == null || serialNos.Count == 0)
            {
                return result;
            }

            // Chunk to keep query size reasonable.
            const int chunkSize = 200;
            for (int offset = 0; offset < serialNos.Count; offset += chunkSize)
            {
                var chunk = serialNos.Skip(offset).Take(chunkSize).ToArray();
                var parameterNames = new List<string>(chunk.Length);
                for (int i = 0; i < chunk.Length; i++)
                {
                    parameterNames.Add("@SerialNumber" + i);
                }

                string inClause = string.Join(",", parameterNames);
                string query =
                    $"SELECT serial_no, template FROM attendance_machine_face_templates " +
                    $"WHERE serial_no IN ({inClause}) AND is_active = 1";

                using (var cmd = new MySqlCommand(query, connection))
                {
                    cmd.CommandTimeout = 300;
                    for (int i = 0; i < chunk.Length; i++)
                    {
                        cmd.Parameters.AddWithValue(parameterNames[i], chunk[i]);
                    }

                    using (var reader = cmd.ExecuteReader())
                    {
                        while (reader.Read())
                        {
                            var serial = reader.IsDBNull(0) ? null : reader.GetString(0);
                            if (string.IsNullOrWhiteSpace(serial))
                            {
                                continue;
                            }

                            byte[] blob = null;
                            if (!reader.IsDBNull(1))
                            {
                                blob = (byte[])reader["template"];
                            }

                            result[serial] = blob ?? Array.Empty<byte>();
                        }
                    }
                }
            }

            return result;
        }

        /// <summary>All active template serial numbers (CENTRAL hub scope).</summary>
        public List<string> GetActiveSerialNumbersAll(MySqlConnection connection)
        {
            var list = new List<string>();
            const string query = "SELECT serial_no FROM hrms.attendance_machine_face_templates WHERE is_active = 1";
            using (var cmd = new MySqlCommand(query, connection))
            {
                cmd.CommandTimeout = 120;
                using (var reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        if (reader.IsDBNull(0)) continue;
                        var s = reader.GetString(0);
                        if (!string.IsNullOrWhiteSpace(s))
                        {
                            list.Add(s.Trim());
                        }
                    }
                }
            }

            return list;
        }

        /// <summary>
        /// Serial numbers that have an active template and appear on scoped machines (SITE deployment).
        /// </summary>
        public List<string> GetActiveSerialNumbersForScopedMachines(MySqlConnection connection, IReadOnlyList<string> machineIds)
        {
            var result = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            if (machineIds == null || machineIds.Count == 0)
            {
                return new List<string>();
            }

            const int chunkSize = 80;
            for (int offset = 0; offset < machineIds.Count; offset += chunkSize)
            {
                var chunk = machineIds.Skip(offset).Take(chunkSize).ToArray();
                var parameterNames = new List<string>(chunk.Length);
                for (int i = 0; i < chunk.Length; i++)
                {
                    parameterNames.Add("@Mid" + i);
                }

                string inClause = string.Join(",", parameterNames);
                string query =
                    "SELECT DISTINCT t.serial_no " +
                    "FROM hrms.attendance_machine_face_templates t " +
                    "INNER JOIN hrms.attendance_machine_user u ON u.serial_number = t.serial_no AND u.is_deleted = 0 " +
                    "WHERE t.is_active = 1 AND u.machine_id IN (" + inClause + ")";

                using (var cmd = new MySqlCommand(query, connection))
                {
                    cmd.CommandTimeout = 120;
                    for (int i = 0; i < chunk.Length; i++)
                    {
                        cmd.Parameters.AddWithValue(parameterNames[i], chunk[i]);
                    }

                    using (var reader = cmd.ExecuteReader())
                    {
                        while (reader.Read())
                        {
                            if (reader.IsDBNull(0)) continue;
                            var s = reader.GetString(0);
                            if (!string.IsNullOrWhiteSpace(s))
                            {
                                result.Add(s.Trim());
                            }
                        }
                    }
                }
            }

            return result.ToList();
        }

        /// <summary>
        /// Active template serial numbers for employees in the given departments (HRMS employees table).
        /// When department lookup is unavailable, returns an empty list and the caller should fall back.
        /// </summary>
        public List<string> GetActiveSerialNumbersByDepartmentIds(
            MySqlConnection connection,
            IReadOnlyList<string> departmentIds,
            IReadOnlyList<string> allowedMachineIds)
        {
            var result = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            if (departmentIds == null || departmentIds.Count == 0)
            {
                return new List<string>();
            }

            var machineIds = (allowedMachineIds ?? Array.Empty<string>())
                .Where(id => !string.IsNullOrWhiteSpace(id))
                .Select(id => id.Trim())
                .Distinct(StringComparer.OrdinalIgnoreCase)
                .ToList();

            const int chunkSize = 80;
            for (int offset = 0; offset < departmentIds.Count; offset += chunkSize)
            {
                var deptChunk = departmentIds.Skip(offset).Take(chunkSize).ToArray();
                var deptParamNames = new List<string>(deptChunk.Length);
                for (int i = 0; i < deptChunk.Length; i++)
                {
                    deptParamNames.Add("@Dept" + i);
                }

                string deptInClause = string.Join(",", deptParamNames);
                string machineJoin = "";
                string machineFilter = "";
                if (machineIds.Count > 0)
                {
                    var machineParamNames = new List<string>(machineIds.Count);
                    for (int i = 0; i < machineIds.Count; i++)
                    {
                        machineParamNames.Add("@Mid" + i);
                    }
                    machineJoin = " INNER JOIN hrms.attendance_machine_user u ON u.serial_number = t.serial_no AND u.is_deleted = 0 ";
                    machineFilter = " AND u.machine_id IN (" + string.Join(",", machineParamNames) + ") ";
                }

                string query =
                    "SELECT DISTINCT t.serial_no " +
                    "FROM hrms.attendance_machine_face_templates t " +
                    "INNER JOIN hrms.employee e ON CAST(e.emp_id AS CHAR) = t.serial_no " +
                    machineJoin +
                    "WHERE t.is_active = 1 AND e.department_id IN (" + deptInClause + ")" +
                    machineFilter;

                using (var cmd = new MySqlCommand(query, connection))
                {
                    cmd.CommandTimeout = 120;
                    for (int i = 0; i < deptChunk.Length; i++)
                    {
                        cmd.Parameters.AddWithValue(deptParamNames[i], deptChunk[i]);
                    }
                    for (int i = 0; i < machineIds.Count; i++)
                    {
                        cmd.Parameters.AddWithValue("@Mid" + i, machineIds[i]);
                    }

                    using (var reader = cmd.ExecuteReader())
                    {
                        while (reader.Read())
                        {
                            if (reader.IsDBNull(0)) continue;
                            var s = reader.GetString(0);
                            if (!string.IsNullOrWhiteSpace(s))
                            {
                                result.Add(s.Trim());
                            }
                        }
                    }
                }
            }

            return result.ToList();
        }

        /// <summary>
        /// Active templates for employees registered on a specific Nedo machine.
        /// Registration-based target selection: attendance_machine_user (is_deleted=0) drives which employees are allowed.
        /// </summary>
        public Dictionary<string, byte[]> GetActiveTemplatesForRegisteredMachine(MySqlConnection connection, string machineId)
        {
            var result = new Dictionary<string, byte[]>(StringComparer.OrdinalIgnoreCase);
            if (string.IsNullOrWhiteSpace(machineId))
            {
                return result;
            }

            const string query =
                "SELECT t.serial_no, t.template " +
                "FROM hrms.attendance_machine_face_templates t " +
                "INNER JOIN hrms.attendance_machine_user u ON u.serial_number = t.serial_no " +
                "WHERE t.is_active = 1 AND u.is_deleted = 0 AND u.machine_id = @MachineId";

            using (var cmd = new MySqlCommand(query, connection))
            {
                cmd.CommandTimeout = 120;
                cmd.Parameters.AddWithValue("@MachineId", machineId);

                using (var reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        if (reader.IsDBNull(0)) continue;
                        var serial = reader.GetString(0);
                        if (string.IsNullOrWhiteSpace(serial)) continue;

                        byte[] blob = Array.Empty<byte>();
                        if (!reader.IsDBNull(1))
                        {
                            blob = (byte[])reader["template"];
                        }

                        result[serial.Trim()] = blob;
                    }
                }
            }

            return result;
        }

        /// <summary>
        /// For each serial_no, return machine_ids where the employee is registered (attendance_machine_user),
        /// restricted to the allowedMachineIds list (scope) and to Nedo machines (exclude ZKTECO by machine_type).
        /// </summary>
        public Dictionary<string, List<string>> GetRegisteredTargetMachineIdsForSerialNos(
            MySqlConnection connection,
            IReadOnlyList<string> serialNos,
            IReadOnlyList<string> allowedMachineIds)
        {
            var result = new Dictionary<string, List<string>>(StringComparer.OrdinalIgnoreCase);
            if (serialNos == null || serialNos.Count == 0)
            {
                return result;
            }

            var allowedSet = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            if (allowedMachineIds != null)
            {
                foreach (var id in allowedMachineIds)
                {
                    if (!string.IsNullOrWhiteSpace(id))
                    {
                        allowedSet.Add(id.Trim());
                    }
                }
            }

            if (allowedSet.Count == 0)
            {
                return result;
            }

            const int serialChunkSize = 200;
            var allowedList = allowedSet.ToList();

            // Keep allowed-machine IN clause reasonably small.
            const int allowedChunkSize = 100;
            for (int offset = 0; offset < serialNos.Count; offset += serialChunkSize)
            {
                var serialChunk = serialNos.Skip(offset).Take(serialChunkSize).ToArray();
                var serialParamNames = new List<string>(serialChunk.Length);
                for (int i = 0; i < serialChunk.Length; i++)
                {
                    serialParamNames.Add("@S" + i);
                }

                string serialInClause = string.Join(",", serialParamNames);

                for (int ao = 0; ao < allowedList.Count; ao += allowedChunkSize)
                {
                    var allowedChunk = allowedList.Skip(ao).Take(allowedChunkSize).ToArray();
                    var allowedParamNames = new List<string>(allowedChunk.Length);
                    for (int i = 0; i < allowedChunk.Length; i++)
                    {
                        allowedParamNames.Add("@A" + i);
                    }
                    string allowedInClause = string.Join(",", allowedParamNames);

                    const string query =
                        "SELECT u.serial_number, u.machine_id " +
                        "FROM hrms.attendance_machine_user u " +
                        "INNER JOIN hrms.attendance_machine m ON m.machine_id = u.machine_id " +
                        "WHERE u.is_deleted = 0 " +
                        "AND (m.machine_type IS NULL OR m.machine_type <> 'ZKTECO') " +
                        "AND u.serial_number IN ({SERIAL_IN}) " +
                        "AND u.machine_id IN ({ALLOWED_IN})";

                    string q = query
                        .Replace("{SERIAL_IN}", serialInClause)
                        .Replace("{ALLOWED_IN}", allowedInClause);

                    using (var cmd = new MySqlCommand())
                    {
                        cmd.Connection = connection;
                        cmd.CommandTimeout = 120;
                        string typeClause = MachineScope.BuildMachineTypeWhereClause(cmd, "m.machine_type", "mtreg" + offset + ao);
                        cmd.CommandText = q.Replace("AND (m.machine_type IS NULL OR m.machine_type <> 'ZKTECO')", "AND " + typeClause);
                        for (int i = 0; i < serialChunk.Length; i++)
                        {
                            cmd.Parameters.AddWithValue(serialParamNames[i], serialChunk[i]);
                        }
                        for (int i = 0; i < allowedChunk.Length; i++)
                        {
                            cmd.Parameters.AddWithValue(allowedParamNames[i], allowedChunk[i]);
                        }

                        using (var reader = cmd.ExecuteReader())
                        {
                            // temp set per serial to avoid duplicates from allowed-chunk partitioning
                            var serialToSet = new Dictionary<string, HashSet<string>>(StringComparer.OrdinalIgnoreCase);

                            while (reader.Read())
                            {
                                if (reader.IsDBNull(0) || reader.IsDBNull(1)) continue;
                                var serial = reader.GetString(0);
                                var mid = reader.GetString(1);
                                if (string.IsNullOrWhiteSpace(serial) || string.IsNullOrWhiteSpace(mid)) continue;

                                if (!serialToSet.TryGetValue(serial, out var set))
                                {
                                    set = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
                                    serialToSet[serial] = set;
                                }
                                set.Add(mid.Trim());
                            }

                            foreach (var kvp in serialToSet)
                            {
                                if (!result.TryGetValue(kvp.Key, out var list))
                                {
                                    list = new List<string>();
                                    result[kvp.Key] = list;
                                }

                                foreach (var mid in kvp.Value)
                                {
                                    if (!list.Contains(mid))
                                    {
                                        list.Add(mid);
                                    }
                                }
                            }
                        }
                    }
                }
            }

            return result;
        }
    }
}