// internal/weather/utils.go
package weather

import (
	"os"
	"strconv"
	"strings"
	"time"
)

// GetEnv gets environment variable with default
func GetEnv(key, defaultValue string) string {
	if value := os.Getenv(key); value != "" {
		return value
	}
	return defaultValue
}

// ParseDuration parses duration string
func ParseDuration(s string) time.Duration {
	d, err := time.ParseDuration(s)
	if err != nil {
		return 5 * time.Minute
	}
	return d
}

// ParseInt parses integer string
func ParseInt(s string) int {
	i, err := strconv.Atoi(s)
	if err != nil {
		return 0
	}
	return i
}

// ParseFloat parses float string
func ParseFloat(s string) float64 {
	f, err := strconv.ParseFloat(s, 64)
	if err != nil {
		return 0
	}
	return f
}

// ParseTopics parses comma-separated topics
func ParseTopics(s string) []string {
	if s == "" {
		return []string{
			"weather/obs/fmi/#",
			"weather/forecast/fmi/#",
		}
	}
	return strings.Split(s, ",")
}

// LoadWatermark loads last observation time from file
func LoadWatermark(filename string) time.Time {
	b, err := os.ReadFile(filename)
	if err != nil {
		return time.Now().UTC().Add(-24 * time.Hour)
	}
	sec, err := strconv.ParseInt(strings.TrimSpace(string(b)), 10, 64)
	if err != nil {
		return time.Now().UTC().Add(-24 * time.Hour)
	}
	return time.Unix(sec, 0).UTC()
}

// StoreWatermark stores observation time to file
func StoreWatermark(filename string, t time.Time) error {
	data := []byte(strconv.FormatInt(t.Unix(), 10))
	return os.WriteFile(filename, data, 0644)
}

// InitTopicStats initializes topic statistics
func InitTopicStats() *TopicStats {
	return &TopicStats{
		MessagesReceived: make(map[string]int),
		LastMessageTime:  make(map[string]time.Time),
	}
}