using System;
using System.Collections.Generic;

namespace HanvonF710XAttendanceService
{
    internal delegate bool MachineUserDeleteBatchDelegate(IReadOnlyList<string> deviceEnrollIds, out string error);

    internal delegate void MachineUserDeletedDelegate(string serialNumber);

    internal sealed class MachineUserDeleteSyncResult
    {
        public int TotalPending { get; set; }
        public int SuccessCount { get; set; }
        public int FailedCount { get; set; }
    }

    internal static class MachineUserDeleteSync
    {
        public static MachineUserDeleteSyncResult Execute(
            string machineId,
            string targetIp,
            IReadOnlyList<MachineUserDeleteItem> pendingItems,
            int batchSize,
            MachineUserDeleteBatchDelegate deleteBatch,
            MachineUserDeletedDelegate markDeleted,
            Action<string> log)
        {
            var result = new MachineUserDeleteSyncResult();
            if (pendingItems == null || pendingItems.Count == 0)
            {
                return result;
            }

            result.TotalPending = pendingItems.Count;
            var batches = MachineUserDeleteBatcher.SplitIntoBatches(pendingItems, batchSize);
            int totalBatches = batches.Count;

            log?.Invoke($"[USER_DELETE] machine={machineId} target={targetIp} pending={result.TotalPending} batchSize={batchSize} batches={totalBatches}");

            for (int batchIndex = 0; batchIndex < batches.Count; batchIndex++)
            {
                var batch = batches[batchIndex];
                int batchNumber = batchIndex + 1;
                var deviceIds = new List<string>(batch.Count);
                foreach (var item in batch)
                {
                    if (!string.IsNullOrWhiteSpace(item.DeviceEnrollId))
                    {
                        deviceIds.Add(item.DeviceEnrollId);
                    }
                }

                log?.Invoke($"[USER_DELETE] batch={batchNumber}/{totalBatches} count={batch.Count}");

                if (deviceIds.Count == 0)
                {
                    log?.Invoke($"[USER_DELETE] batch={batchNumber}/{totalBatches} result=FAILED err=no_device_ids");
                    result.FailedCount += batch.Count;
                    continue;
                }

                string error = null;
                if (deleteBatch == null || !deleteBatch(deviceIds, out error))
                {
                    log?.Invoke($"[USER_DELETE] batch={batchNumber}/{totalBatches} result=FAILED err={error ?? "deleteusers failed"}");
                    result.FailedCount += batch.Count;
                    continue;
                }

                foreach (var item in batch)
                {
                    markDeleted?.Invoke(item.SerialNumber);
                }

                result.SuccessCount += batch.Count;
                log?.Invoke($"[USER_DELETE] batch={batchNumber}/{totalBatches} result=SUCCESS");
            }

            log?.Invoke($"[USER_DELETE] machine={machineId} total={result.TotalPending} success={result.SuccessCount} failed={result.FailedCount}");
            return result;
        }
    }
}