initial commit

lib/cache.go

@@ -0,0 +1,63 @@
+package lib
+
+import (
+	"encoding/csv"
+	"os"
+	"strings"
+)
+
+type Cache struct {
+	filePath string
+	seen     map[string]bool
+}
+
+func NewCache(filePath string) (*Cache, error) {
+	c := &Cache{
+		filePath: filePath,
+		seen:     make(map[string]bool),
+	}
+	if err := c.load(); err != nil {
+		return nil, err
+	}
+	return c, nil
+}
+
+func (c *Cache) load() error {
+	f, err := os.Open(c.filePath)
+	if os.IsNotExist(err) {
+		return nil
+	}
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	records, err := csv.NewReader(f).ReadAll()
+	if err != nil {
+		return err
+	}
+	for _, record := range records {
+		if len(record) > 0 {
+			c.seen[strings.TrimSpace(record[0])] = true
+		}
+	}
+	return nil
+}
+
+func (c *Cache) Has(id string) bool {
+	return c.seen[id]
+}
+
+func (c *Cache) Add(id string) error {
+	c.seen[id] = true
+
+	f, err := os.OpenFile(c.filePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+
+	w := csv.NewWriter(f)
+	defer w.Flush()
+	return w.Write([]string{id})
+}