namespace ScadaLink.Host;

/// <summary>
/// Validates required configuration before Akka.NET actor system creation.
/// Runs early in startup to fail fast with clear error messages.
/// </summary>
public static class StartupValidator
{
    public static void Validate(IConfiguration configuration)
    {
        var errors = new List<string>();

        var nodeSection = configuration.GetSection("ScadaLink:Node");
        var role = nodeSection["Role"];
        if (string.IsNullOrEmpty(role) || (role != "Central" && role != "Site"))
            errors.Add("ScadaLink:Node:Role must be 'Central' or 'Site'");

        if (string.IsNullOrEmpty(nodeSection["NodeHostname"]))
            errors.Add("ScadaLink:Node:NodeHostname is required");

        var portStr = nodeSection["RemotingPort"];
        if (!int.TryParse(portStr, out var port) || port < 1 || port > 65535)
            errors.Add("ScadaLink:Node:RemotingPort must be 1-65535");

        if (role == "Site" && string.IsNullOrEmpty(nodeSection["SiteId"]))
            errors.Add("ScadaLink:Node:SiteId is required for Site nodes");

        if (role == "Central")
        {
            var dbSection = configuration.GetSection("ScadaLink:Database");
            if (string.IsNullOrEmpty(dbSection["ConfigurationDb"]))
                errors.Add("ScadaLink:Database:ConfigurationDb connection string required for Central");
            if (string.IsNullOrEmpty(dbSection["MachineDataDb"]))
                errors.Add("ScadaLink:Database:MachineDataDb connection string required for Central");

            var secSection = configuration.GetSection("ScadaLink:Security");
            if (string.IsNullOrEmpty(secSection["LdapServer"]))
                errors.Add("ScadaLink:Security:LdapServer required for Central");
            if (string.IsNullOrEmpty(secSection["JwtSigningKey"]))
                errors.Add("ScadaLink:Security:JwtSigningKey required for Central");
        }

        if (role == "Site")
        {
            var grpcPortStr = nodeSection["GrpcPort"];
            if (grpcPortStr != null && (!int.TryParse(grpcPortStr, out var gp) || gp < 1 || gp > 65535))
                errors.Add("ScadaLink:Node:GrpcPort must be 1-65535");

            var dbSection = configuration.GetSection("ScadaLink:Database");
            if (string.IsNullOrEmpty(dbSection["SiteDbPath"]))
                errors.Add("ScadaLink:Database:SiteDbPath required for Site nodes");
        }

        var seedNodes = configuration.GetSection("ScadaLink:Cluster:SeedNodes").Get<List<string>>();
        if (seedNodes == null || seedNodes.Count < 2)
            errors.Add("ScadaLink:Cluster:SeedNodes must have at least 2 entries");

        if (errors.Count > 0)
            throw new InvalidOperationException(
                $"Configuration validation failed:\n{string.Join("\n", errors.Select(e => $"  - {e}"))}");
    }
}