using System;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace PayRollDAL.DTO.GateEntry
{
    /// <summary>
    /// Accepts both a JSON number and a JSON string so that:
    ///   • single-item QR  → "batchQty": 14158.6          (number)
    ///   • multi-item  QR  → "batchQty": "14158.6,14155"  (string)
    /// Both deserialise to a string that the DAL splits and parses.
    /// </summary>
    internal sealed class FlexibleDecimalStringConverter : JsonConverter<string>
    {
        public override string Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
            => reader.TokenType == JsonTokenType.Number
                ? reader.GetDecimal().ToString(System.Globalization.CultureInfo.InvariantCulture)
                : reader.GetString();

        public override void Write(Utf8JsonWriter writer, string value, JsonSerializerOptions options)
            => writer.WriteStringValue(value);
    }

    /// <summary>
    /// Parses InvoiceDate from multiple formats the QR scanner may emit:
    ///   "01.05.2026"  (DD.MM.YYYY — printed on the label)
    ///   "2026-03-31"  (ISO 8601 — standard API format)
    ///   "01/05/2026"  (DD/MM/YYYY)
    /// Returns null when the string is absent or unparseable.
    /// </summary>
    internal sealed class FlexibleDateOnlyConverter : JsonConverter<DateOnly?>
    {
        private static readonly string[] _Formats =
        {
            "dd.MM.yyyy",    // 01.05.2026
            "yyyy-MM-dd",    // 2026-03-31
            "dd/MM/yyyy",    // 01/05/2026
            "MM/dd/yyyy",    // 05/01/2026
            "d.M.yyyy",      // 1.5.2026
        };

        public override DateOnly? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
        {
            var s = reader.GetString();
            if (string.IsNullOrWhiteSpace(s)) return null;

            if (DateOnly.TryParseExact(s, _Formats,
                    System.Globalization.CultureInfo.InvariantCulture,
                    System.Globalization.DateTimeStyles.None, out var d))
                return d;

            return DateOnly.TryParse(s,
                    System.Globalization.CultureInfo.InvariantCulture,
                    System.Globalization.DateTimeStyles.None, out var d2)
                ? d2 : (DateOnly?)null;
        }

        public override void Write(Utf8JsonWriter writer, DateOnly? value, JsonSerializerOptions options)
        {
            if (value.HasValue) writer.WriteStringValue(value.Value.ToString("yyyy-MM-dd"));
            else                writer.WriteNullValue();
        }
    }

    /// <summary>
    /// Raw text values from a QR scanner / event sheet.
    ///
    /// SINGLE-ITEM (normal):
    ///   One object → one resolved detail row.
    ///   All fields are plain scalar values.
    ///
    /// MULTI-ITEM (comma-encoded):
    ///   One object → N resolved detail rows.
    ///   Per-item fields (MaterialCode, BatchNo, BatchQty, InvoiceQty,
    ///   AllocationName, UOMName, Remarks) carry N comma-separated values.
    ///   Header fields (SupplierName, PONumber, InvoiceNumber, InvoiceDate)
    ///   are shared across all expanded rows.
    ///
    ///   Example — 2 items in one object:
    ///     "materialCode": "SB/1622/C000/NA000/1270,SB/1622/C000/NA000/1271"
    ///     "batchNo":      "15G2600104,15G2600105"
    ///     "batchQty":     "14158.6,14155"
    ///     "invoiceQty":   "14158.6,141544.6"
    ///
    ///   Rules:
    ///     • Count = max number of comma-separated tokens across all per-item fields.
    ///     • Fields with fewer tokens than Count reuse their last value for the
    ///       remaining rows (safe broadcast).
    ///     • Fields with exactly 1 token are broadcast to all rows unchanged.
    /// </summary>
    public class GateEntryDetailRawInputDTO
    {
        // ── Header fields (shared across all expanded rows) ──────────────

        /// <summary>Supplier party name — resolves to PartyId/PartyCode on the gate entry header.</summary>
        public string SupplierName { get; set; }

        /// <summary>PO document number (e.g. "VFG/PO-III/4076/2025-26") — resolves to DocumentId, DocumentNumber.</summary>
        public string PONumber { get; set; }

        /// <summary>Invoice number (e.g. "S5D25260924") — stored as ReferenceNumber on the gate entry header.</summary>
        public string InvoiceNumber { get; set; }

        /// <summary>
        /// Invoice date — stored as ReferenceDate on the gate entry header.
        /// Accepts "01.05.2026" (DD.MM.YYYY), "2026-03-31" (ISO), or "01/05/2026".
        /// </summary>
        [JsonConverter(typeof(FlexibleDateOnlyConverter))]
        public DateOnly? InvoiceDate { get; set; }

        // ── Per-item fields (comma-separated for multi-item QR) ──────────

        /// <summary>
        /// Material code or name. Comma-separated for multi-item QR.
        /// Resolved first by ITEMCODE, then by ITEMNAME.
        /// </summary>
        public string MaterialCode { get; set; }

        /// <summary>Batch / lot number. Comma-separated for multi-item QR.</summary>
        public string BatchNo { get; set; }

        /// <summary>
        /// Batch quantity → LotQuantity. Comma-separated for multi-item QR.
        /// Accepts both JSON number (14158.6) and JSON string ("14158.6,14155").
        /// </summary>
        [JsonConverter(typeof(FlexibleDecimalStringConverter))]
        public string BatchQty { get; set; }

        /// <summary>
        /// Invoice quantity → DocumentValue. Comma-separated for multi-item QR.
        /// Accepts both JSON number and JSON string.
        /// </summary>
        [JsonConverter(typeof(FlexibleDecimalStringConverter))]
        public string InvoiceQty { get; set; }

        /// <summary>Allocation name. Comma-separated for multi-item QR.</summary>
        public string AllocationName { get; set; }

        /// <summary>Unit of measure name. Comma-separated for multi-item QR.</summary>
        public string UOMName { get; set; }

        /// <summary>Free-text remarks. Comma-separated for multi-item QR.</summary>
        public string Remarks { get; set; }
    }
}