// Package checker periodically HTTP-checks services and updates status.json.
package checker

import (
	"log"
	"net/http"
	"path/filepath"
	"time"

	"ridgwaysystems.org/website/internal/status"
)

// Start launches the background checker. It checks services every interval
// and updates status.json in dataDir. Services without a CheckURL are skipped.
func Start(dataDir string, interval time.Duration) {
	go run(dataDir, interval)
}

func run(dataDir string, interval time.Duration) {
	client := &http.Client{
		Timeout: 10 * time.Second,
		CheckRedirect: func(req *http.Request, via []*http.Request) error {
			if len(via) >= 3 {
				return http.ErrUseLastResponse
			}
			return nil
		},
	}
	path := filepath.Join(dataDir, "status.json")

	for {
		check(client, path)
		time.Sleep(interval)
	}
}

func check(client *http.Client, path string) {
	page, err := status.Load(path)
	if err != nil {
		log.Printf("checker: load %s: %v", path, err)
		return
	}

	changed := false
	for i, svc := range page.Services {
		if svc.CheckURL == "" {
			continue
		}

		prev := svc.Status
		newStatus := probe(client, svc.CheckURL)
		if newStatus != prev {
			log.Printf("checker: %s %s → %s", svc.Name, prev, newStatus)
			page.Services[i].Status = newStatus
			changed = true
		}
	}

	if changed {
		if err := status.Save(path, page); err != nil {
			log.Printf("checker: save %s: %v", path, err)
		}
	} else {
		// Still update last_checked timestamp so the status page shows freshness
		page.LastChecked = time.Now().UTC()
		if err := status.Save(path, page); err != nil {
			log.Printf("checker: save %s: %v", path, err)
		}
	}
}

func probe(client *http.Client, url string) string {
	resp, err := client.Get(url)
	if err != nil {
		return "down"
	}
	defer resp.Body.Close()

	switch {
	case resp.StatusCode < 400:
		return "up"
	case resp.StatusCode >= 500:
		return "down"
	default:
		// 4xx could mean the service is up but the URL is wrong; treat as degraded
		return "degraded"
	}
}