using System.Globalization;
using System.Text.Json;

namespace Infrastructure.StockData;

/// <summary>
/// KRX OpenAPI(data-dbg.krx.co.kr) 사회책임투자채권 정보(esg/sri_bond_info) 응답 파서 — 순수 C# (System.Text.Json).
/// 응답 골격: { "OutBlock_1": [ { BAS_DD, ISUR_NM, ISU_CD, SRI_BND_TP_NM, ISU_NM, LIST_DD, ISU_DD, REDMPT_DD, ISU_RT, ISU_AMT, LIST_AMT, BND_TP_NM }, ... ] }.
/// 가격/거래량이 아니라 발행 정보 스냅샷이다. 날짜(LIST_DD/ISU_DD/REDMPT_DD)는 yyyyMMdd, 미제공/오류 시 null. 금액은 원 단위 long, 표면이자율(ISU_RT)은 decimal %.
/// 채권 일별매매(bon)와 shape 이 완전히 달라 별도 파서. 표준코드(ISU_CD)는 12자리 ISIN 원문 유지.
/// </summary>
public static class KrxSriBondParser
{
    /// <summary>사회책임투자채권 정보 1행 (날짜/표면이자율은 결측 시 null)</summary>
    public sealed record SriBondRow(
        string Code,
        DateOnly TradeDate,
        string IssuerName,
        string SriBondType,
        string Name,
        DateOnly? ListDate,
        DateOnly? IssueDate,
        DateOnly? RedemptionDate,
        decimal? CouponRate,
        long IssueAmount,
        long ListAmount,
        string? BondType
    );

    public static IReadOnlyList<SriBondRow> ParseDaily(string json)
    {
        using var doc = JsonDocument.Parse(json);
        var rows = new List<SriBondRow>();

        if (!doc.RootElement.TryGetProperty("OutBlock_1", out var block) || block.ValueKind != JsonValueKind.Array)
        {
            return rows;
        }

        foreach (var item in block.EnumerateArray())
        {
            var code = ToNull(GetString(item, "ISU_CD"));
            var issuerName = GetString(item, "ISUR_NM");
            var name = GetString(item, "ISU_NM");
            var tradeDate = ParseDate(GetString(item, "BAS_DD"));

            if (code is null || issuerName.Length == 0 || name.Length == 0 || tradeDate is null)
            {
                continue;
            }

            rows.Add(new SriBondRow(
                code,
                tradeDate.Value,
                issuerName,
                GetString(item, "SRI_BND_TP_NM"),
                name,
                ParseNullableDate(GetString(item, "LIST_DD")),
                ParseNullableDate(GetString(item, "ISU_DD")),
                ParseNullableDate(GetString(item, "REDMPT_DD")),
                ParseNullableDecimal(GetString(item, "ISU_RT")),
                ParseLong(GetString(item, "ISU_AMT")),
                ParseLong(GetString(item, "LIST_AMT")),
                ToNull(GetString(item, "BND_TP_NM"))
            ));
        }

        return rows;
    }

    private static string GetString(JsonElement element, string name)
    {
        if (!element.TryGetProperty(name, out var value))
        {
            return string.Empty;
        }

        return value.ValueKind switch
        {
            JsonValueKind.String => value.GetString()?.Trim() ?? string.Empty,
            JsonValueKind.Number => value.GetRawText(),
            _ => string.Empty
        };
    }

    /// <summary>빈 문자열/"-" 은 null, 나머지는 trim 값</summary>
    private static string? ToNull(string raw)
    {
        return raw.Length == 0 || raw == "-" ? null : raw;
    }

    /// <summary>기준일자(BAS_DD) — 필수. 파싱 실패는 null(행 제외).</summary>
    private static DateOnly? ParseDate(string raw)
    {
        return DateOnly.TryParseExact(raw, "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var date) ? date : null;
    }

    /// <summary>상장일/발행일/상환일 — yyyyMMdd. 빈값/오류는 null.</summary>
    private static DateOnly? ParseNullableDate(string raw)
    {
        return DateOnly.TryParseExact(raw, "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var date) ? date : null;
    }

    private static long ParseLong(string raw)
    {
        return long.TryParse(raw, NumberStyles.Integer | NumberStyles.AllowThousands, CultureInfo.InvariantCulture, out var value) ? value : 0L;
    }

    /// <summary>표면이자율(%) — "" 나 "-" 등 파싱 실패는 null (0% 과 구분)</summary>
    private static decimal? ParseNullableDecimal(string raw)
    {
        return decimal.TryParse(raw, NumberStyles.Float | NumberStyles.AllowThousands, CultureInfo.InvariantCulture, out var value) ? value : null;
    }
}