using System.Data;
using System.Diagnostics;
using Microsoft.Data.SqlClient;

namespace Gateway.Data;

public class SqlService
{
    private readonly IConfiguration _config;
    private readonly ILogger<SqlService> _logger;

    public SqlService(IConfiguration config, ILogger<SqlService> logger)
    {
        _config = config;
        _logger = logger;
    }

    private string GetConnectionString()
    {
        // expects env var: ConnectionStrings__Sql
        var cs = _config.GetConnectionString("Sql");
        if (string.IsNullOrWhiteSpace(cs))
            throw new InvalidOperationException("Missing connection string: ConnectionStrings:Sql (env var ConnectionStrings__Sql).");
        return cs;
    }

    /// <summary>
    /// Executes a stored procedure using the standard signature:
    ///   @action varchar(..),
    ///   @rqst nvarchar(max),
    ///   @resp nvarchar(max) OUTPUT
    /// Returns the output JSON string (resp).
    /// </summary>
    public async Task<string> ExecProcAsync(
        string procName,
        string action,
        string rqstJson,
        int commandTimeoutSeconds = 60,
        CancellationToken ct = default)
    {
        if (string.IsNullOrWhiteSpace(procName))
            throw new ArgumentException("procName is required.", nameof(procName));
        if (string.IsNullOrWhiteSpace(action))
            throw new ArgumentException("action is required.", nameof(action));
        if (string.IsNullOrWhiteSpace(rqstJson))
            rqstJson = "{}";

        var sw = Stopwatch.StartNew();

        try
        {
            await using var conn = new SqlConnection(GetConnectionString());
            await conn.OpenAsync(ct);

            await using var cmd = new SqlCommand(procName, conn)
            {
                CommandType = CommandType.StoredProcedure,
                CommandTimeout = commandTimeoutSeconds
            };

            cmd.Parameters.Add(new SqlParameter("@action", SqlDbType.VarChar, 50) { Value = action });
            cmd.Parameters.Add(new SqlParameter("@rqst", SqlDbType.NVarChar, -1) { Value = rqstJson });

            var pResp = new SqlParameter("@resp", SqlDbType.NVarChar, -1)
            {
                Direction = ParameterDirection.Output
            };
            cmd.Parameters.Add(pResp);

            await cmd.ExecuteNonQueryAsync(ct);

            var resp = pResp.Value as string ?? "";

            sw.Stop();
            _logger.LogInformation("SQL ok: {Proc} action={Action} ms={Ms}", procName, action, sw.ElapsedMilliseconds);

            return resp;
        }
        catch (SqlException ex)
        {
            sw.Stop();
            _logger.LogError(ex, "SQL error: {Proc} action={Action} ms={Ms}", procName, action, sw.ElapsedMilliseconds);
            throw;
        }
        catch (Exception ex)
        {
            sw.Stop();
            _logger.LogError(ex, "App error calling SQL: {Proc} action={Action} ms={Ms}", procName, action, sw.ElapsedMilliseconds);
            throw;
        }
    }
}