package metrics

import (
	"encoding/json"
	"net/http"
	"os"
	"regexp"
	"strings"

	log "github.com/sirupsen/logrus"
)

type MetricConfig struct {
	Url           string
	BotUserAgents *[]regexp.Regexp
	Enabled       bool
}

// Checks if we should send a metric ping to page-metrics based on the served path.
func (c *MetricConfig) ShouldSendMetrics(path, userAgent, dnt, gpc string) bool {
	if !strings.HasSuffix(path, ".html") || !c.Enabled {
		return false
	}

	// Ignore requests where the user have set "Do-Not-Track" or "Do-Not-Sell-My-Data", even though
	// there is no user data and we're not selling it.
	if dnt == "1" || gpc == "1" {
		return false
	}

	// Filter out bots
	for _, pattern := range *c.BotUserAgents {
		if pattern.MatchString(userAgent) {
			return false
		}
	}

	return true
}

func (c *MetricConfig) SendMetricPing(domain, path, referrer string) {
	data := map[string]string{
		"domain":  domain,
		"path":    path,
		"referer": referrer,
	}
	jsonData, err := json.Marshal(data)
	if err != nil {
		log.Errorf("Failed to send metric ping: %v", err)
		return
	}

	log.Debugf("Sending payload %s", string(jsonData))

	// Send the ping to the server
	go func() {
		res, err := http.Post(
			c.Url,
			"application/json",
			strings.NewReader(string(jsonData)),
		)
		if err != nil {
			log.Errorf("Failed to send payload to: %v", err)
			return
		}

		defer res.Body.Close()
		if res.StatusCode != 200 {
			log.Errorf("Server returned non-200 status code %d", res.StatusCode)
		}
	}()
}

// Reads a JSON array of bot user agents from disk and parses them
// into regular expressions.
func ReadBotPatterns(file string) ([]regexp.Regexp, error) {
	content, err := os.ReadFile(file)
	if err != nil {
		log.Warnf("Failed to read bot metrics file: %v", err)
		return []regexp.Regexp{}, err
	}

	var payload []string
	err = json.Unmarshal(content, &payload)
	if err != nil {
		log.Warnf("Failed to unmarshal file: %v", err)
		return []regexp.Regexp{}, err
	}

	patterns := make([]regexp.Regexp, 0)
	for _, v := range payload {
		patterns = append(
			patterns,
			*regexp.MustCompile(v),
		)
	}

	return patterns, nil
}