Add initial login logic

1 files changed, 58 insertions, 0 deletions

diff --git a/conn_pool.go b/conn_pool.go
new file mode 100644
index 0000000..147c022
--- /dev/null
+++ b/conn_pool.go
@@ -0,0 +1,58 @@
+package koushin
+
+import (
+	"crypto/rand"
+	"encoding/base64"
+	"errors"
+
+	imapclient "github.com/emersion/go-imap/client"
+)
+
+func generateToken() (string, error) {
+	b := make([]byte, 32)
+	_, err := rand.Read(b)
+	if err != nil {
+		return "", err
+	}
+	return base64.URLEncoding.EncodeToString(b), nil
+}
+
+var ErrSessionExpired = errors.New("session expired")
+
+// TODO: expiration timer
+type ConnPool struct {
+	// TODO: add synchronization
+	conns map[string]*imapclient.Client
+}
+
+func NewConnPool() *ConnPool {
+	return &ConnPool{
+		conns: make(map[string]*imapclient.Client),
+	}
+}
+
+func (pool *ConnPool) Get(token string) (*imapclient.Client, error) {
+	conn, ok := pool.conns[token]
+	if !ok {
+		return nil, ErrSessionExpired
+	}
+	return conn, nil
+}
+
+func (pool *ConnPool) Put(conn *imapclient.Client) (token string, err error) {
+	for {
+		var err error
+		token, err = generateToken()
+		if err != nil {
+			conn.Logout()
+			return "", err
+		}
+
+		if _, ok := pool.conns[token]; !ok {
+			break
+		}
+	}
+
+	pool.conns[token] = conn
+	return token, nil
+}