Code refactoring + made anomaly detection system more stable.

cache/statistics.go

@@ -0,0 +1,93 @@
+package cache
+
+import (
+	"fmt"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ceticamarco/zephyr/types"
+)
+
+// statistic cache data type, representing a mapping between a location+date and its daily average temperature
+type StatCache struct {
+	mu sync.RWMutex
+	db map[string]float64
+}
+
+func InitStatCache() *StatCache {
+	return &StatCache{
+		db: make(map[string]float64),
+	}
+}
+
+func (cache *StatCache) AddStatistic(cityName string, statDate string, dailyTemp float64) {
+	cache.mu.Lock()
+	defer cache.mu.Unlock()
+
+	// Format key as '<DATE>@<LOCATION>
+	key := fmt.Sprintf("%s@%s", statDate, cityName)
+
+	// Insert weather statistic into the database if it doesn't already exist
+	if _, exists := cache.db[key]; exists {
+		return
+	}
+
+	cache.db[key] = dailyTemp
+}
+
+func (cache *StatCache) IsKeyInvalid(key string) bool {
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
+
+	// A key is invalid if it has less than 2 entries within the last 2 days
+	threshold := time.Now().AddDate(0, 0, -2)
+
+	var validEntries uint = 0
+	for storedKey := range cache.db {
+		if !strings.HasSuffix(storedKey, key) {
+			continue
+		}
+
+		// Get <DATE> from <DATE>@<LOCATION>
+		keyDate, err := time.Parse("2006-01-02", strings.Split(storedKey, "@")[0])
+		if err != nil {
+			keyDate = time.Now() // Add a fallback date if parsing fails
+		}
+
+		if !keyDate.Before(threshold) {
+			validEntries++
+
+			// Early skip if we already found two valid entries
+			if validEntries >= 2 {
+				return false
+			}
+		}
+	}
+
+	return true
+}
+
+func (cache *StatCache) GetCityStatistics(cityName string) []types.StatElement {
+	cache.mu.RLock()
+	defer cache.mu.RUnlock()
+
+	result := make([]types.StatElement, 0)
+
+	for key, record := range cache.db {
+		if strings.HasSuffix(key, cityName) {
+			// Get <DATE> from <DATE>@<LOCATION>
+			keyDate, err := time.Parse("2006-01-02", strings.Split(key, "@")[0])
+			if err != nil {
+				keyDate = time.Now() // Add a fallback date if parsing fails
+			}
+
+			result = append(result, types.StatElement{
+				Temperature: record,
+				Date:        keyDate,
+			})
+		}
+	}
+
+	return result
+}