using Microsoft.Data.SqlClient;

namespace MxNativeClient;

public sealed record GalaxyUserProfile(
    int UserProfileId,
    string UserProfileName,
    Guid UserGuid,
    string DefaultSecurityGroup,
    int? InTouchAccessLevel,
    IReadOnlyList<string> Roles);

public sealed class GalaxyRepositoryUserResolver
{
    private const string DefaultConnectionString =
        "Server=localhost;Database=ZB;Integrated Security=True;Encrypt=False;TrustServerCertificate=True";

    private readonly string _connectionString;

    public GalaxyRepositoryUserResolver(string connectionString = DefaultConnectionString)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(connectionString);
        _connectionString = connectionString;
    }

    public async Task<int> ResolveUserProfileIdByGuidAsync(
        Guid userGuid,
        CancellationToken cancellationToken = default)
    {
        GalaxyUserProfile profile = await ResolveByGuidAsync(userGuid, cancellationToken).ConfigureAwait(false);
        return profile.UserProfileId;
    }

    public async Task<GalaxyUserProfile> ResolveByGuidAsync(
        Guid userGuid,
        CancellationToken cancellationToken = default)
    {
        await using var connection = new SqlConnection(_connectionString);
        await connection.OpenAsync(cancellationToken).ConfigureAwait(false);

        await using var command = connection.CreateCommand();
        command.CommandText = UserByGuidSql;
        command.Parameters.AddWithValue("@userGuid", userGuid);

        await using SqlDataReader reader = await command.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false);
        if (!await reader.ReadAsync(cancellationToken).ConfigureAwait(false))
        {
            throw new KeyNotFoundException($"Galaxy user GUID {userGuid} was not found in dbo.user_profile.");
        }

        return ReadProfile(reader);
    }

    public async Task<GalaxyUserProfile> ResolveByNameAsync(
        string userName,
        CancellationToken cancellationToken = default)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(userName);

        await using var connection = new SqlConnection(_connectionString);
        await connection.OpenAsync(cancellationToken).ConfigureAwait(false);

        await using var command = connection.CreateCommand();
        command.CommandText = UserByNameSql;
        command.Parameters.AddWithValue("@userName", userName);

        await using SqlDataReader reader = await command.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false);
        if (!await reader.ReadAsync(cancellationToken).ConfigureAwait(false))
        {
            throw new KeyNotFoundException($"Galaxy user {userName} was not found in dbo.user_profile.");
        }

        return ReadProfile(reader);
    }

    private static GalaxyUserProfile ReadProfile(SqlDataReader reader)
    {
        return new GalaxyUserProfile(
            reader.GetInt32(0),
            reader.GetString(1),
            reader.GetGuid(2),
            reader.GetString(3),
            reader.IsDBNull(4) ? null : reader.GetInt32(4),
            reader.IsDBNull(5) ? [] : ParseRoleBlob(reader.GetString(5)));
    }

    private static IReadOnlyList<string> ParseRoleBlob(string rolesText)
    {
        if (!rolesText.StartsWith("0x", StringComparison.OrdinalIgnoreCase) || rolesText.Length <= 2)
        {
            return [];
        }

        byte[] bytes = Convert.FromHexString(rolesText[2..]);
        List<string> roles = [];
        for (int offset = 0; offset + 3 < bytes.Length; offset++)
        {
            List<char> chars = [];
            int cursor = offset;
            while (cursor + 1 < bytes.Length)
            {
                char c = (char)(bytes[cursor] | (bytes[cursor + 1] << 8));
                if (c == '\0')
                {
                    break;
                }

                if (c < 0x20 || c > 0x7e)
                {
                    chars.Clear();
                    break;
                }

                chars.Add(c);
                cursor += 2;
            }

            if (chars.Count < 2 || cursor + 1 >= bytes.Length || bytes[cursor] != 0 || bytes[cursor + 1] != 0)
            {
                continue;
            }

            string role = new(chars.ToArray());
            if (!roles.Contains(role, StringComparer.OrdinalIgnoreCase))
            {
                roles.Add(role);
            }

            offset = cursor;
        }

        return roles;
    }

    private const string UserSelectSql = """
SELECT TOP (1)
    user_profile_id,
    user_profile_name,
    user_guid,
    default_security_group,
    intouch_access_level,
    CONVERT(nvarchar(max), roles) AS roles_text
FROM dbo.user_profile
""";

    private const string UserByGuidSql = UserSelectSql + "\nWHERE user_guid = @userGuid\nORDER BY user_profile_id";

    private const string UserByNameSql = UserSelectSql + "\nWHERE user_profile_name = @userName\nORDER BY user_profile_id";
}