using System.Globalization;



namespace FoodLabeling.Application.Helpers;



/// <summary>

/// Reports Print Log 日期时间展示：统一为 <c>MM/dd/yy HH:mm</c>（精确到分钟）。

/// </summary>

public static class ReportsDateTimeDisplayHelper

{

    public const string DisplayFormat = "MM/dd/yy HH:mm";



    private static readonly string[] ExpiryParseFormats =

    {

        DisplayFormat,

        "MM/dd/yy",

        "MM/dd",

        "yyyy-MM-dd H:mm",

        "yyyy-MM-dd",

        "yyyy/MM/dd HH:mm",

        "yyyy/MM/dd",

        "MM/dd/yyyy hh:mm tt",

        "MM/dd/yyyy h:mm tt",

        "MM/dd/yyyy HH:mm",

        "MM/dd/yyyy",

        "M/d/yyyy hh:mm tt",

        "M/d/yyyy h:mm tt",

        "M/d/yyyy",

        "dd/MM/yyyy HH:mm",

        "dd/MM/yyyy",

        "d/M/yyyy HH:mm",

        "d/M/yyyy",

    };



    /// <summary>打印时间展示（Printed at 列）</summary>

    public static string FormatPrintedAt(DateTime printedAt)

    {

        if (printedAt == DateTime.MinValue)

        {

            return "无";

        }



        return printedAt.ToString(DisplayFormat, CultureInfo.InvariantCulture);

    }



    /// <summary>保质期展示（Expiration 列）：解析后统一为 <see cref="DisplayFormat"/>。</summary>

    public static string FormatExpiryDisplay(string? raw, DateTime? anchor = null)

    {

        if (string.IsNullOrWhiteSpace(raw) || string.Equals(raw.Trim(), "无", StringComparison.Ordinal))

        {

            return "无";

        }



        var s = raw.Trim();

        if (TryParseToDateTime(s, out var dt))

        {

            return dt.ToString(DisplayFormat, CultureInfo.InvariantCulture);

        }



        if (anchor.HasValue && TryParsePartialDateTime(s, anchor.Value, out dt))

        {

            return dt.ToString(DisplayFormat, CultureInfo.InvariantCulture);

        }



        return s;

    }



    /// <summary>合并日期片段（如 07/09）与时间片段（如 11:56），缺少年份时用 anchor 补全。</summary>

    public static string MergeDateAndTimeParts(string datePart, string timePart, DateTime anchor)

    {

        var date = datePart.Trim();

        var time = timePart.Trim();

        if (string.IsNullOrWhiteSpace(date))

        {

            return string.IsNullOrWhiteSpace(time) ? "无" : time;

        }



        if (!TryParsePartialDateTime(date, anchor, out var dt) && !TryParseToDateTime(date, out dt))

        {

            return string.IsNullOrWhiteSpace(time) ? date : $"{date} {time}";

        }



        if (!string.IsNullOrWhiteSpace(time))

        {

            var timeMatch = System.Text.RegularExpressions.Regex.Match(

                time,

                @"^(?<h>\d{1,2}):(?<m>\d{2})",

                System.Text.RegularExpressions.RegexOptions.CultureInvariant);

            if (timeMatch.Success &&

                int.TryParse(timeMatch.Groups["h"].Value, out var h) &&

                int.TryParse(timeMatch.Groups["m"].Value, out var m))

            {

                dt = new DateTime(dt.Year, dt.Month, dt.Day, h, m, 0, dt.Kind);

            }

        }



        return dt.ToString(DisplayFormat, CultureInfo.InvariantCulture);

    }



    private static bool TryParsePartialDateTime(string s, DateTime anchor, out DateTime dt)

    {

        dt = default;

        var text = s.Trim();

        var timeMatch = System.Text.RegularExpressions.Regex.Match(

            text,

            @"^(?<date>\d{1,2}/\d{1,2}(?:/\d{2,4})?)\s+(?<time>\d{1,2}:\d{2})$",

            System.Text.RegularExpressions.RegexOptions.CultureInvariant);

        if (timeMatch.Success)

        {

            text = timeMatch.Groups["date"].Value;

            if (TryParsePartialDateOnly(text, anchor, out dt))

            {

                var timePart = timeMatch.Groups["time"].Value;

                var parts = timePart.Split(':');

                if (parts.Length == 2 &&

                    int.TryParse(parts[0], out var h) &&

                    int.TryParse(parts[1], out var m))

                {

                    dt = new DateTime(dt.Year, dt.Month, dt.Day, h, m, 0, dt.Kind);

                    return true;

                }

            }

        }



        return TryParsePartialDateOnly(text, anchor, out dt);

    }



    private static bool TryParsePartialDateOnly(string s, DateTime anchor, out DateTime dt)

    {

        dt = default;

        var parts = s.Split('/');

        if (parts.Length is < 2 or > 3)

        {

            return false;

        }



        if (!int.TryParse(parts[0], out var month) || !int.TryParse(parts[1], out var day))

        {

            return false;

        }



        var year = anchor.Year;

        if (parts.Length == 3)

        {

            if (!int.TryParse(parts[2], out var y))

            {

                return false;

            }



            year = parts[2].Length == 2 ? 2000 + y : y;

        }



        try

        {

            dt = new DateTime(year, month, day, 0, 0, 0, anchor.Kind);

            return true;

        }

        catch

        {

            return false;

        }

    }



    private static bool TryParseToDateTime(string s, out DateTime dt)

    {

        if (DateTime.TryParse(

                s,

                CultureInfo.InvariantCulture,

                DateTimeStyles.AllowWhiteSpaces | DateTimeStyles.AssumeLocal,

                out dt))

        {

            return true;

        }



        if (DateTime.TryParse(

                s,

                CultureInfo.GetCultureInfo("en-US"),

                DateTimeStyles.AllowWhiteSpaces | DateTimeStyles.AssumeLocal,

                out dt))

        {

            return true;

        }



        foreach (var fmt in ExpiryParseFormats)

        {

            if (DateTime.TryParseExact(

                    s,

                    fmt,

                    CultureInfo.InvariantCulture,

                    DateTimeStyles.AllowWhiteSpaces | DateTimeStyles.AssumeLocal,

                    out dt))

            {

                return true;

            }



            if (DateTime.TryParseExact(

                    s,

                    fmt,

                    CultureInfo.GetCultureInfo("en-US"),

                    DateTimeStyles.AllowWhiteSpaces | DateTimeStyles.AssumeLocal,

                    out dt))

            {

                return true;

            }

        }



        return false;
    }

    /// <summary>将已解析的到期时刻格式化为 Print Log 展示文案。</summary>
    public static string FormatExpiryDateTime(DateTime dt)
    {
        if (dt == DateTime.MinValue)
        {
            return "无";
        }

        return dt.ToString(DisplayFormat, CultureInfo.InvariantCulture);
    }

    /// <summary>解析到期字面量（含 anchor 补全年份/时间）。</summary>
    public static bool TryParseExpiryDateTime(string s, DateTime anchor, out DateTime dt)
    {
        if (TryParseToDateTime(s, out dt))
        {
            return true;
        }

        return TryParsePartialDateTime(s, anchor, out dt);
    }
}