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

namespace Jugenddienst_Stunden.Models;

internal sealed class JsonFlexibleInt32Converter : JsonConverter<int> {
    public override int Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) {
        switch (reader.TokenType) {
            case JsonTokenType.Number:
                if (reader.TryGetInt32(out var n)) return n;
                // Fallback via double to cover edge cases
                var d = reader.GetDouble();
                return (int)d;
            case JsonTokenType.String:
                var s = reader.GetString();
                if (string.IsNullOrWhiteSpace(s)) return 0;
                s = s.Trim();
                // Some APIs embed id like "141|..." -> take leading numeric part
                int i = 0;
                int sign = 1;
                int idx = 0;
                if (s.StartsWith("-")) { sign = -1; idx = 1; }
                for (; idx < s.Length; idx++) {
                    char c = s[idx];
                    if (c < '0' || c > '9') break;
                    i = i * 10 + (c - '0');
                }
                if (idx > 0 && (idx > 1 || sign == 1)) return i * sign;
                if (int.TryParse(s, out var parsed)) return parsed;
                if (long.TryParse(s, out var l)) return (int)l;
                throw new JsonException($"Cannot convert string '{s}' to Int32.");
            case JsonTokenType.Null:
                return 0;
            default:
                throw new JsonException($"Token {reader.TokenType} is not valid for Int32.");
        }
    }

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

internal sealed class JsonFlexibleNullableInt32Converter : JsonConverter<int?> {
    public override int? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) {
        if (reader.TokenType == JsonTokenType.Null) return null;
        // Reuse non-nullable converter
        var conv = new JsonFlexibleInt32Converter();
        return conv.Read(ref reader, typeof(int), options);
    }

    public override void Write(Utf8JsonWriter writer, int? value, JsonSerializerOptions options) {
        if (value.HasValue) writer.WriteNumberValue(value.Value);
        else writer.WriteNullValue();
    }
}