using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using System.Globalization;
using System.IO;
using CsvHelper;
using CsvHelper.Configuration;
using FATrace.WPLApp.ModelDto;
using Prism.Mvvm;

namespace FATrace.WPLApp.Services
{
    /// <summary>
    /// CSV服务
    ///导出CSV文件
    /// </summary>
    public class CsvServices:BindableBase
    {
        public ILogService LogService { get; }
        public IFreeSql FreeSql { get; }

        public CsvServices(ILogService logService, IFreeSql freeSql)
        {
            LogService = logService;
            FreeSql = freeSql;
        }

        /// <summary>
        /// 导出单条记录为 CSV 文件，文件名即记录的 InBagCode（自动追加 .csv 扩展名）。
        /// </summary>
        /// <param name="item">要导出的数据项，类型为 RawProUserCsvDto</param>
        /// <param name="outputDirectory">导出目录，不存在将自动创建</param>
        /// <param name="overwrite">若目标文件已存在，是否允许覆盖</param>
        /// <returns>导出后的完整文件路径</returns>
        /// <exception cref="ArgumentNullException">item 或 outputDirectory 为 null</exception>
        /// <exception cref="ArgumentException">InBagCode 为空或仅空白</exception>
        /// <exception cref="IOException">文件已存在且不允许覆盖</exception>
        public string ExportSingle(RawProUserCsvDto item, string outputDirectory, bool overwrite = false)
        {
            if (item is null) throw new ArgumentNullException(nameof(item));
            if (outputDirectory is null) throw new ArgumentNullException(nameof(outputDirectory));

            var inBagCode = (item.InBagCode ?? string.Empty).Trim();
            if (string.IsNullOrWhiteSpace(inBagCode))
                throw new ArgumentException("InBagCode 不能为空", nameof(item.InBagCode));

            // 目录确保存在
            Directory.CreateDirectory(outputDirectory);

            var safeName = SanitizeFileName(inBagCode);
            var filePath = Path.Combine(outputDirectory, safeName + ".csv");

            if (File.Exists(filePath) && !overwrite)
            {
                throw new IOException($"文件已存在且不允许覆盖: {filePath}");
            }

            // 使用 UTF8 BOM，便于 Excel 正确识别中文
            using var writer = new StreamWriter(filePath, false, new UTF8Encoding(encoderShouldEmitUTF8Identifier: true));
            using var csv = new CsvWriter(writer, CultureInfo.InvariantCulture);

            // 固定列顺序映射，并设置日期格式
            csv.Context.RegisterClassMap<RawProUserCsvDtoMap>();

            csv.WriteHeader<RawProUserCsvDto>();
            csv.NextRecord();
            csv.WriteRecord(item);
            csv.NextRecord();

            return filePath;
        }

        /// <summary>
        /// 批量导出：把每一条记录分别导出为以各自 InBagCode 命名的 CSV 文件。
        /// </summary>
        /// <param name="items">数据集合</param>
        /// <param name="outputDirectory">导出目录，不存在将自动创建</param>
        /// <param name="overwrite">若目标文件已存在，是否允许覆盖</param>
        /// <returns>成功导出的文件完整路径集合</returns>
        public IEnumerable<string> ExportMany(IEnumerable<RawProUserCsvDto> items, string outputDirectory, bool overwrite = false)
        {
            if (items is null) throw new ArgumentNullException(nameof(items));

            var results = new List<string>();
            foreach (var item in items)
            {
                // 逐条导出，沿用相同规则
                var path = ExportSingle(item, outputDirectory, overwrite);
                results.Add(path);
            }
            return results;
        }

        /// <summary>
        /// 清理文件名中的非法字符。
        /// </summary>
        private static string SanitizeFileName(string name)
        {
            var invalid = Path.GetInvalidFileNameChars();
            var sb = new StringBuilder(name.Length);
            foreach (var ch in name)
            {
                sb.Append(invalid.Contains(ch) ? '_' : ch);
            }
            return sb.ToString();
        }

        /// <summary>
        /// RawProUserCsvDto 的 CSV 列映射，固定输出顺序并设置日期格式。
        /// </summary>
        private sealed class RawProUserCsvDtoMap : ClassMap<RawProUserCsvDto>
        {
            public RawProUserCsvDtoMap()
            {
                Map(x => x.RawCode).Index(0).Name(nameof(RawProUserCsvDto.RawCode));
                Map(x => x.RawName).Index(1).Name(nameof(RawProUserCsvDto.RawName));
                Map(x => x.InBagCode).Index(2).Name(nameof(RawProUserCsvDto.InBagCode));
                Map(x => x.BoxCode).Index(3).Name(nameof(RawProUserCsvDto.BoxCode));
                Map(x => x.Batch).Index(4).Name(nameof(RawProUserCsvDto.Batch));
                Map(x => x.ShelfLife).Index(5).Name(nameof(RawProUserCsvDto.ShelfLife));
                Map(x => x.Weight).Index(6).Name(nameof(RawProUserCsvDto.Weight));
                Map(x => x.DeliveryDate).Index(7).Name(nameof(RawProUserCsvDto.DeliveryDate));
                Map(x => x.RemainWeight).Index(8).Name(nameof(RawProUserCsvDto.RemainWeight));
                Map(x => x.StockWeight).Index(9).Name(nameof(RawProUserCsvDto.StockWeight));
                Map(x => x.WeightTime).Index(10).Name(nameof(RawProUserCsvDto.WeightTime)).TypeConverterOption.Format("yyyy-MM-dd HH:mm:ss");
                Map(x => x.OpUser).Index(11).Name(nameof(RawProUserCsvDto.OpUser));
                Map(x => x.CheckUser).Index(12).Name(nameof(RawProUserCsvDto.CheckUser));
                Map(x => x.OutTime).Index(13).Name(nameof(RawProUserCsvDto.OutTime)).TypeConverterOption.Format("yyyy-MM-dd HH:mm:ss");
            }
        }
    }
}