using System.Text.RegularExpressions;
using MiniExcelLibs;

namespace Oms.Application.Shared;

/// <summary>
/// 国家/地区 Excel 模板与导入解析。
/// </summary>
public static class CountryImportHelper
{
    public const string TemplateSheetName = "导入模板";
    public const string TemplateFileName = "国家地区导入模板.xlsx";

    private static readonly Regex CountryCodePattern = new("^[A-Za-z]{2}$", RegexOptions.Compiled);

    private static readonly Dictionary<string, string> HeaderAliases = new(StringComparer.OrdinalIgnoreCase)
    {
        ["国家二字码"] = nameof(CountryImportRow.CountryCode),
        ["二字码"] = nameof(CountryImportRow.CountryCode),
        ["国家代码"] = nameof(CountryImportRow.CountryCode),
        ["CountryCode"] = nameof(CountryImportRow.CountryCode),
        ["countryCode"] = nameof(CountryImportRow.CountryCode),
        ["中文名"] = nameof(CountryImportRow.ChineseName),
        ["国家中文名"] = nameof(CountryImportRow.ChineseName),
        ["ChineseName"] = nameof(CountryImportRow.ChineseName),
        ["chineseName"] = nameof(CountryImportRow.ChineseName),
        ["英文名"] = nameof(CountryImportRow.EnglishName),
        ["国家英文名"] = nameof(CountryImportRow.EnglishName),
        ["EnglishName"] = nameof(CountryImportRow.EnglishName),
        ["englishName"] = nameof(CountryImportRow.EnglishName),
    };

    public static async Task<byte[]> BuildTemplateBytesAsync()
    {
        var templateRows = new List<Dictionary<string, object?>>
        {
            new()
            {
                ["国家二字码"] = "CN",
                ["中文名"] = "中国",
                ["英文名"] = "China"
            },
            new()
            {
                ["国家二字码"] = "US",
                ["中文名"] = "美国",
                ["英文名"] = "United States"
            }
        };

        var sheets = new Dictionary<string, object>
        {
            [TemplateSheetName] = templateRows
        };

        await using var stream = new MemoryStream();
        await MiniExcel.SaveAsAsync(stream, sheets);
        return stream.ToArray();
    }

    public static async Task<List<(int RowNumber, CountryImportRow Row)>> ParseImportRowsAsync(Stream fileStream)
    {
        if (fileStream.CanSeek)
        {
            fileStream.Position = 0;
        }

        var sheetNames = MiniExcel.GetSheetNames(fileStream);
        var sheetName = sheetNames.FirstOrDefault(x =>
                           string.Equals(x, TemplateSheetName, StringComparison.OrdinalIgnoreCase))
                       ?? sheetNames.FirstOrDefault();

        if (fileStream.CanSeek)
        {
            fileStream.Position = 0;
        }

        var rows = await MiniExcel.QueryAsync(fileStream, useHeaderRow: true, sheetName: sheetName);
        var result = new List<(int RowNumber, CountryImportRow Row)>();
        var rowNumber = 1;

        foreach (var row in rows)
        {
            rowNumber++;
            if (row is not IDictionary<string, object> rowDict || IsEmptyRow(rowDict))
            {
                continue;
            }

            result.Add((rowNumber, ParseRow(rowDict)));
        }

        return result;
    }

    public static void Normalize(CountryImportRow row)
    {
        row.CountryCode = row.CountryCode?.Trim().ToUpperInvariant() ?? string.Empty;
        row.ChineseName = row.ChineseName?.Trim() ?? string.Empty;
        row.EnglishName = row.EnglishName?.Trim() ?? string.Empty;

        if (string.IsNullOrWhiteSpace(row.CountryCode))
        {
            throw new InvalidOperationException("国家二字码不能为空");
        }

        if (!CountryCodePattern.IsMatch(row.CountryCode))
        {
            throw new InvalidOperationException("国家二字码须为 2 位字母，如 CN、US");
        }

        if (string.IsNullOrWhiteSpace(row.ChineseName))
        {
            throw new InvalidOperationException("中文名不能为空");
        }

        if (row.ChineseName.Length > 128)
        {
            throw new InvalidOperationException("中文名不可超过 128 个字符");
        }

        if (string.IsNullOrWhiteSpace(row.EnglishName))
        {
            throw new InvalidOperationException("英文名不能为空");
        }

        if (row.EnglishName.Length > 128)
        {
            throw new InvalidOperationException("英文名不可超过 128 个字符");
        }
    }

    private static CountryImportRow ParseRow(IDictionary<string, object> rowDict)
    {
        var mapped = new Dictionary<string, string?>(StringComparer.OrdinalIgnoreCase);
        foreach (var (header, value) in rowDict)
        {
            if (string.IsNullOrWhiteSpace(header) || !HeaderAliases.TryGetValue(header.Trim(), out var field))
            {
                continue;
            }

            mapped[field] = NormalizeCell(value);
        }

        return new CountryImportRow
        {
            CountryCode = mapped.GetValueOrDefault(nameof(CountryImportRow.CountryCode)) ?? string.Empty,
            ChineseName = mapped.GetValueOrDefault(nameof(CountryImportRow.ChineseName)) ?? string.Empty,
            EnglishName = mapped.GetValueOrDefault(nameof(CountryImportRow.EnglishName)) ?? string.Empty
        };
    }

    private static string? NormalizeCell(object? value)
    {
        if (value is null)
        {
            return null;
        }

        var text = Convert.ToString(value, System.Globalization.CultureInfo.InvariantCulture)?.Trim();
        return string.IsNullOrWhiteSpace(text) ? null : text;
    }

    private static bool IsEmptyRow(IDictionary<string, object> rowDict) =>
        rowDict.Values.All(value => string.IsNullOrWhiteSpace(NormalizeCell(value)));
}

/// <summary>
/// 国家导入行。
/// </summary>
public class CountryImportRow
{
    public string CountryCode { get; set; } = string.Empty;

    public string ChineseName { get; set; } = string.Empty;

    public string EnglishName { get; set; } = string.Empty;
}