package config

import (
	"os"
	"time"
)

type Config struct {
	Addr         string
	DBPath       string
	ArchiveAfter time.Duration

	// StaleAfter is how long a firing alert may go without a refreshing webhook
	// before the sweeper treats it as resolved. It must exceed Alertmanager's
	// repeat_interval (default 4h), which is what refreshes the alert.
	StaleAfter time.Duration

	// DeadmanMatchers selects the alerts that are heartbeats rather than
	// problems: receiving one opens no incident, and the absence of one does.
	//
	// ";" separates matchers, "," the label conditions within one, "=" is exact
	// equality — `alertname=Watchdog,cluster=prod; alertname=Heartbeat`. Every
	// matcher must name an alertname. See api.ParseDeadmanConfig.
	DeadmanMatchers string

	// DeadmanTimeout is how long a heartbeat may go unheard before its switch is
	// declared dead. It must be *shorter* than the Alertmanager repeat_interval
	// of the route carrying the heartbeat — the opposite of StaleAfter, and the
	// reason a dead man's switch usually wants a route of its own. Zero disables
	// dead man's switch handling entirely.
	DeadmanTimeout time.Duration

	// DeadmanSeverity is the severity a dead man's switch incident opens at.
	// These incidents have no member alerts to derive one from.
	DeadmanSeverity string

	// NtfyURL is the ntfy server push notifications are published to. Empty
	// disables notifications entirely.
	NtfyURL string

	// NtfyToken is an optional bearer token for an access-controlled ntfy.
	NtfyToken string

	// NtfyFallbackTopic receives incidents that open with nobody on call.
	NtfyFallbackTopic string

	// PublicURL is the base URL a phone uses to reach this server, used for the
	// link and the Acknowledge button inside a notification. Without it
	// notifications carry neither.
	PublicURL string

	// NotifyRepeat is how long an incident may sit unacknowledged before it is
	// notified again. Zero disables reminders.
	NotifyRepeat time.Duration
}

func Load() Config {
	addr := os.Getenv("TERDUT_ADDR")
	if addr == "" {
		addr = ":8080"
	}
	dbPath := os.Getenv("TERDUT_DB_PATH")
	if dbPath == "" {
		dbPath = "terdut.db"
	}
	deadmanMatchers := os.Getenv("TERDUT_DEADMAN_MATCHERS")
	if deadmanMatchers == "" {
		deadmanMatchers = "alertname=Watchdog"
	}
	deadmanSeverity := os.Getenv("TERDUT_DEADMAN_SEVERITY")
	if deadmanSeverity == "" {
		deadmanSeverity = "critical"
	}
	return Config{
		Addr:         addr,
		DBPath:       dbPath,
		ArchiveAfter: duration("TERDUT_ARCHIVE_AFTER", 7*24*time.Hour),
		StaleAfter:   duration("TERDUT_STALE_AFTER", 6*time.Hour),

		DeadmanMatchers: deadmanMatchers,
		DeadmanTimeout:  duration("TERDUT_DEADMAN_TIMEOUT", 15*time.Minute),
		DeadmanSeverity: deadmanSeverity,

		NtfyURL:           os.Getenv("TERDUT_NTFY_URL"),
		NtfyToken:         os.Getenv("TERDUT_NTFY_TOKEN"),
		NtfyFallbackTopic: os.Getenv("TERDUT_NTFY_FALLBACK_TOPIC"),
		PublicURL:         os.Getenv("TERDUT_PUBLIC_URL"),
		NotifyRepeat:      duration("TERDUT_NOTIFY_REPEAT", 15*time.Minute),
	}
}

// duration reads a time.ParseDuration-formatted env var. An unset or
// unparseable value falls back to def rather than failing startup: a typo in one
// tuning knob should not take the server down.
func duration(env string, def time.Duration) time.Duration {
	if s := os.Getenv(env); s != "" {
		if d, err := time.ParseDuration(s); err == nil {
			return d
		}
	}
	return def
}