using Core;
using KubernetesWorkflow;
using System.Text;

namespace MetricsPlugin
{
    public class PrometheusStarter
    {
        private readonly IPluginTools tools;

        public PrometheusStarter(IPluginTools tools)
        {
            this.tools = tools;
        }

        public RunningContainers CollectMetricsFor(IMetricsScrapeTarget[] targets)
        {
            Log($"Starting metrics server for {targets.Length} targets...");
            var startupConfig = new StartupConfig();
            startupConfig.Add(new PrometheusStartupConfig(GeneratePrometheusConfig(targets)));

            var workflow = tools.CreateWorkflow();
            var runningContainers = workflow.Start(1, Location.Unspecified, new PrometheusContainerRecipe(), startupConfig);
            if (runningContainers.Containers.Length != 1) throw new InvalidOperationException("Expected only 1 Prometheus container to be created.");

            Log("Metrics server started.");
            return runningContainers;
        }

        public MetricsAccess CreateAccessForTarget(RunningContainers metricsContainer, IMetricsScrapeTarget target)
        {
            var metricsQuery = new MetricsQuery(tools, metricsContainer);
            return new MetricsAccess(metricsQuery, target);
        }

        private void Log(string msg)
        {
            tools.GetLog().Log(msg);
        }

        private static string GeneratePrometheusConfig(IMetricsScrapeTarget[] targets)
        {
            var config = "";
            config += "global:\n";
            config += "  scrape_interval: 10s\n";
            config += "  scrape_timeout: 10s\n";
            config += "\n";
            config += "scrape_configs:\n";
            config += "  - job_name: services\n";
            config += "    metrics_path: /metrics\n";
            config += "    static_configs:\n";
            config += "      - targets:\n";

            foreach (var target in targets)
            {
                config += $"          - '{target.Ip}:{target.Port}'\n";
            }

            var bytes = Encoding.ASCII.GetBytes(config);
            return Convert.ToBase64String(bytes);
        }
    }
}