using Microsoft.Extensions.Diagnostics.HealthChecks;
using ZB.MOM.WW.ScadaBridge.ConfigurationDatabase;

namespace ZB.MOM.WW.ScadaBridge.Host.Health;

/// <summary>
/// Health check that verifies database connectivity for Central nodes.
/// </summary>
public class DatabaseHealthCheck : IHealthCheck
{
    private readonly ScadaBridgeDbContext _dbContext;

    /// <summary>
    /// Initializes a new <see cref="DatabaseHealthCheck"/>.
    /// </summary>
    /// <param name="dbContext">The EF Core database context used to test connectivity.</param>
    public DatabaseHealthCheck(ScadaBridgeDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    /// <summary>
    /// Checks database connectivity by attempting to open a connection.
    /// </summary>
    /// <param name="context">Health check context providing failure status information.</param>
    /// <param name="cancellationToken">Cancellation token for the check.</param>
    public async Task<HealthCheckResult> CheckHealthAsync(
        HealthCheckContext context,
        CancellationToken cancellationToken = default)
    {
        try
        {
            var canConnect = await _dbContext.Database.CanConnectAsync(cancellationToken);
            return canConnect
                ? HealthCheckResult.Healthy("Database connection is available.")
                : HealthCheckResult.Unhealthy("Database connection failed.");
        }
        catch (Exception ex)
        {
            return HealthCheckResult.Unhealthy("Database connection failed.", ex);
        }
    }
}