feature: implement most AbuseIPDB endpoints

* implement all but report-bulk endpoint
* basic tests done

pkg/abuseipdb/rate/ratelimit.go

@@ -0,0 +1,51 @@
+package rate
+
+import (
+	"net/http"
+	"strconv"
+	"time"
+)
+
+type Category int
+
+const (
+	CheckCategory Category = iota
+	ReportsCategory
+	BlacklistCategory
+	ReportCategory
+	CheckBlockCategory
+	BulkReportCategory
+	ClearAddressCategory
+)
+
+type Limit struct {
+	RetryAfter          time.Time `header:"Retry-After"`
+	XRateLimitLimit     int       `header:"X-RateLimit-Limit"`
+	XRateLimitRemaining int       `header:"X-RateLimit-Remaining"`
+	XRateLimitReset     time.Time `header:"X-RateLimit-Reset"`
+}
+
+type Limits map[Category]*Limit
+
+func (l *Limits) Update(category Category, header http.Header) error {
+	limit := &Limit{}
+	for key, value := range header {
+		iValue, err := strconv.Atoi(value[0])
+		if err != nil {
+			return err
+		}
+		switch key {
+		case "X-RateLimit-Limit":
+			limit.XRateLimitLimit = iValue
+		case "X-RateLimit-Remaining":
+			limit.XRateLimitRemaining = iValue
+		case "X-RateLimit-Reset":
+			limit.XRateLimitReset = time.Unix(int64(iValue), 0)
+		case "Retry-After":
+			limit.RetryAfter = time.Now().Add(time.Duration(iValue) * time.Second)
+		}
+	}
+
+	(*l)[category] = limit
+	return nil
+}