package zabbixagent

import (
	"context"
	"golang.zabbix.com/sdk/errs"
	"golang.zabbix.com/sdk/metric"
	"golang.zabbix.com/sdk/plugin"
	"golang.zabbix.com/sdk/plugin/container"
	"golang.zabbix.com/sdk/zbxerr"
	"time"
)

type metricKey string

type metricBinding struct {
	metric  *metric.Metric
	handler HandlerFunc
}

type zabbixAgentPlugin struct {
	plugin.Base
	metrics map[metricKey]*metricBinding
}

// Launch launches the plugin. Blocks until plugin execution has finished.
func Launch() error {
	p := &zabbixAgentPlugin{}

	err := p.registerMetrics()
	if err != nil {
		return err
	}

	h, err := container.NewHandler(PluginName)
	if err != nil {
		return errs.Wrap(err, "failed to create new handler")
	}

	p.Logger = &h

	err = h.Execute()
	if err != nil {
		return errs.Wrap(err, "failed to execute plugin handler")
	}

	return nil
}

// Export collects all the metrics.
func (p *zabbixAgentPlugin) Export(key string, rawParams []string, _ plugin.ContextProvider) (any, error) {
	b, ok := p.metrics[metricKey(key)]
	if !ok {
		return nil, errs.Wrapf(zbxerr.ErrorUnsupportedMetric, "unknown metric %q", key)
	}

	metricParams, extraParams, _, err := b.metric.EvalParams(rawParams, nil)
	if err != nil {
		return nil, errs.Wrap(err, "failed to evaluate metric parameters")
	}

	ctx, cancel := context.WithTimeout(
		context.Background(),
		30*time.Second, // TODO: make configurable
	)
	defer cancel()

	res, err := b.handler(ctx, metricParams, extraParams...)
	if err != nil {
		return nil, errs.Wrap(err, "failed to execute handler")
	}

	return res, nil
}

func (p *zabbixAgentPlugin) registerMetrics() error {
	h := NewHandler()

	p.metrics = map[metricKey]*metricBinding{
		"onvif.app.version": {
			metric: metric.New(
				"App version",
				nil,
				false,
			),
			handler: h.GetAppVersion,
		},
		"onvif.httpclient": {
			metric: metric.New(
				"ONVIF HTTP client",
				[]*metric.Param{
					metric.NewParam("method", "HTTP request method."),
					metric.NewParam("url", "HTTP request URL."),
					metric.NewParam("body", "HTTP request body."),
				},
				false,
			),
			handler: h.HTTPClient,
		},
	}

	metricSet := metric.MetricSet{}

	for k, m := range p.metrics {
		metricSet[string(k)] = m.metric
	}

	err := plugin.RegisterMetrics(p, PluginName, metricSet.List()...)
	if err != nil {
		return errs.Wrap(err, "failed to register metrics")
	}

	return nil
}