Added StatDB data type and IsKeyInvalid, AddStatistics methods

types/statDB.go

@@ -0,0 +1,52 @@
+package types
+
+import (
+	"fmt"
+	"strings"
+	"time"
+)
+
+// StatDB data type, representing a mapping between a location and its weather
+type StatDB struct {
+	db map[string]Weather
+}
+
+func InitDB() *StatDB {
+	return &StatDB{
+		db: make(map[string]Weather),
+	}
+}
+
+func (statDB *StatDB) AddStatistic(cityName string, weather Weather) {
+	key := fmt.Sprintf("%s@%s", weather.Date.Date, cityName)
+
+	// Insert weather statistic into the database only if it isn't present
+	if _, isPresent := statDB.db[key]; isPresent {
+		return
+	}
+
+	statDB.db[key] = weather
+}
+
+func (statDB *StatDB) IsKeyInvalid(key string) bool {
+	// A key is invalid if it has less than 2 entries within the last 2 days
+	threshold := time.Now().AddDate(0, 0, -2)
+
+	var validKeys uint = 0
+	for storedKey, record := range statDB.db {
+		if !strings.HasSuffix(storedKey, key) {
+			continue
+		}
+
+		if !record.Date.Date.Before(threshold) {
+			validKeys++
+
+			// Early skip if we already found two valid keys
+			if validKeys >= 2 {
+				return false
+			}
+		}
+	}
+
+	return true
+}

types/statistics.go

@@ -0,0 +1,21 @@
+package types
+
+// The WeatherAnomaly data type, representing
+// skewed meteorological events
+type WeatherAnomaly struct {
+	Date ZephyrDate `json:"date"`
+	Temp float64    `json:"temperature"`
+}
+
+// The StatResult data type, representing weather statistics
+// of past meteorological events
+type StatResult struct {
+	Min     float64        `json:"min"`
+	Max     float64        `json:"max"`
+	Count   int            `json:"count"`
+	Mean    float64        `json:"mean"`
+	StdDev  float64        `json:"stdDev"`
+	Median  float64        `json:"median"`
+	Mode    float64        `json:"mode"`
+	Anomaly WeatherAnomaly `json:"anomaly"`
+}