package prebuilds

import (
	"context"
	"time"

	"cdr.dev/slog"

	"github.com/prometheus/client_golang/prometheus"

	"github.com/coder/coder/v2/coderd/database"
	"github.com/coder/coder/v2/coderd/database/dbauthz"
)

var (
	CreatedPrebuildsDesc   = prometheus.NewDesc("coderd_prebuilds_created", "The number of prebuilds created.", []string{"template_name", "preset_name"}, nil)
	FailedPrebuildsDesc    = prometheus.NewDesc("coderd_prebuilds_failed", "The number of prebuilds that failed.", []string{"template_name", "preset_name"}, nil)
	AssignedPrebuildsDesc  = prometheus.NewDesc("coderd_prebuilds_assigned", "The number of prebuilds that were assigned to a runner.", []string{"template_name", "preset_name"}, nil)
	UsedPresetsDesc        = prometheus.NewDesc("coderd_presets_used", "The number of times a preset was used.", []string{"template_name", "preset_name"}, nil)
	ExhaustedPrebuildsDesc = prometheus.NewDesc("coderd_prebuilds_exhausted", "The number of prebuilds that were exhausted.", []string{"template_name", "preset_name"}, nil)
	DesiredPrebuildsDesc   = prometheus.NewDesc("coderd_prebuilds_desired", "The number of desired prebuilds.", []string{"template_name", "preset_name"}, nil)
	ActualPrebuildsDesc    = prometheus.NewDesc("coderd_prebuilds_actual", "The number of actual prebuilds.", []string{"template_name", "preset_name"}, nil)
	EligiblePrebuildsDesc  = prometheus.NewDesc("coderd_prebuilds_eligible", "The number of eligible prebuilds.", []string{"template_name", "preset_name"}, nil)
)

type MetricsCollector struct {
	database database.Store
	logger   slog.Logger
}

var _ prometheus.Collector = new(MetricsCollector)

func NewMetricsCollector(db database.Store, logger slog.Logger) *MetricsCollector {
	return &MetricsCollector{
		database: db,
		logger:   logger.Named("prebuilds_metrics_collector"),
	}
}

func (*MetricsCollector) Describe(descCh chan<- *prometheus.Desc) {
	descCh <- CreatedPrebuildsDesc
	descCh <- FailedPrebuildsDesc
	descCh <- AssignedPrebuildsDesc
	descCh <- UsedPresetsDesc
	descCh <- ExhaustedPrebuildsDesc
	descCh <- DesiredPrebuildsDesc
	descCh <- ActualPrebuildsDesc
	descCh <- EligiblePrebuildsDesc
}

func (mc *MetricsCollector) Collect(metricsCh chan<- prometheus.Metric) {
	// TODO (sasswart): get a proper actor in here, to deescalate from system
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	// nolint:gocritic // just until we get back to this
	metrics, err := mc.database.GetPrebuildMetrics(dbauthz.AsSystemRestricted(ctx))
	if err != nil {
		mc.logger.Error(ctx, "failed to get prebuild metrics", slog.Error(err))
		return
	}

	for _, metric := range metrics {
		metricsCh <- prometheus.MustNewConstMetric(CreatedPrebuildsDesc, prometheus.CounterValue, float64(metric.Created), metric.TemplateName.String, metric.PresetName.String)
		metricsCh <- prometheus.MustNewConstMetric(FailedPrebuildsDesc, prometheus.CounterValue, float64(metric.Failed), metric.TemplateName.String, metric.PresetName.String)
		metricsCh <- prometheus.MustNewConstMetric(AssignedPrebuildsDesc, prometheus.CounterValue, float64(metric.Assigned), metric.TemplateName.String, metric.PresetName.String)
		metricsCh <- prometheus.MustNewConstMetric(ExhaustedPrebuildsDesc, prometheus.CounterValue, float64(metric.Exhausted), metric.TemplateName.String, metric.PresetName.String)
		metricsCh <- prometheus.MustNewConstMetric(UsedPresetsDesc, prometheus.CounterValue, float64(metric.UsedPreset), metric.TemplateName.String, metric.PresetName.String)
	}

	// TODO (sasswart): read gauges from controller
}