using System.Text.Json;
using System.Text.RegularExpressions;
using IceImportDAL.DTO.EntityPersistenceAdapter;

namespace IceImportBLL.IceImportHttpResponseParser;

// Best-effort parsing of a target entity's ResponseStandardDTO<object> JSON response, since the
// generic Menu/WebService dispatch can't know the target's exact response DTO shape at compile
// time. Save/Update responses follow CLAUDE.md's convention of a message string ending in
// "... with id = {id}" (SuccessResponse.SaveSuccessMessage/UpdateSuccessMessage); Get/GetSelectList
// responses are matched structurally by property-name convention ("...Id", "...Code", "...Name").
internal static class IceImportHttpResponseParser
{
    private static readonly Regex TrailingId = new(@"(\d+)\s*$", RegexOptions.Compiled);

    public static int? TryExtractSavedId(string? responseJson)
    {
        if (string.IsNullOrWhiteSpace(responseJson)) return null;

        try
        {
            using var doc = JsonDocument.Parse(responseJson);
            if (!doc.RootElement.TryGetProperty("Body", out var body)) return null;

            if (body.ValueKind == JsonValueKind.String)
            {
                var match = TrailingId.Match(body.GetString() ?? string.Empty);
                return match.Success && int.TryParse(match.Groups[1].Value, out var id) ? id : null;
            }

            if (body.ValueKind == JsonValueKind.Object)
                return TryExtractIdProperty(body);

            return null;
        }
        catch (JsonException)
        {
            return null;
        }
    }

    public static ExistingKeyDTO? TryExtractExistingKey(string? responseJson)
    {
        if (string.IsNullOrWhiteSpace(responseJson)) return null;

        try
        {
            using var doc = JsonDocument.Parse(responseJson);
            if (!doc.RootElement.TryGetProperty("Body", out var body)) return null;

            var target = body;
            if (body.ValueKind == JsonValueKind.Array)
            {
                using var enumerator = body.EnumerateArray().GetEnumerator();
                if (!enumerator.MoveNext()) return null;
                target = enumerator.Current;
            }

            if (target.ValueKind != JsonValueKind.Object) return null;

            var id = TryExtractIdProperty(target);
            if (id is null) return null;

            int? version = null;
            foreach (var prop in target.EnumerateObject())
            {
                if (string.Equals(prop.Name, "Version", StringComparison.OrdinalIgnoreCase) &&
                    prop.Value.ValueKind == JsonValueKind.Number && prop.Value.TryGetInt32(out var v))
                {
                    version = v;
                    break;
                }
            }

            return new ExistingKeyDTO { Id = id.Value, Version = version };
        }
        catch (JsonException)
        {
            return null;
        }
    }

    // Used by EntityLookupService's Menu/WebService GetSelectList fallback — extracts
    // (code, name, id) from every object in the Body array, using property-name conventions.
    public static IEnumerable<(string Code, string Name, int Id)> ExtractCodeNameIdRows(string? responseJson)
    {
        if (string.IsNullOrWhiteSpace(responseJson)) yield break;

        JsonDocument doc;
        try
        {
            doc = JsonDocument.Parse(responseJson);
        }
        catch (JsonException)
        {
            yield break;
        }

        using (doc)
        {
            if (!doc.RootElement.TryGetProperty("Body", out var body) || body.ValueKind != JsonValueKind.Array)
                yield break;

            foreach (var item in body.EnumerateArray())
            {
                if (item.ValueKind != JsonValueKind.Object) continue;

                string? code = null, name = null;
                int? id = null;

                foreach (var prop in item.EnumerateObject())
                {
                    if (id is null && prop.Name.EndsWith("Id", StringComparison.OrdinalIgnoreCase) &&
                        prop.Value.ValueKind == JsonValueKind.Number && prop.Value.TryGetInt32(out var idVal))
                        id = idVal;
                    else if (code is null && prop.Name.EndsWith("Code", StringComparison.OrdinalIgnoreCase) &&
                             prop.Value.ValueKind == JsonValueKind.String)
                        code = prop.Value.GetString();
                    else if (name is null && prop.Name.EndsWith("Name", StringComparison.OrdinalIgnoreCase) &&
                             prop.Value.ValueKind == JsonValueKind.String)
                        name = prop.Value.GetString();
                }

                if (id is not null)
                    yield return (code ?? string.Empty, name ?? string.Empty, id.Value);
            }
        }
    }

    private static int? TryExtractIdProperty(JsonElement obj)
    {
        foreach (var prop in obj.EnumerateObject())
        {
            if (prop.Name.EndsWith("Id", StringComparison.OrdinalIgnoreCase) &&
                prop.Value.ValueKind == JsonValueKind.Number && prop.Value.TryGetInt32(out var id))
                return id;
        }
        return null;
    }
}