feat: prepare for multiple database types (#4068)

BREAKING CHANGE: the database and admin user config has changed.

internal/database/dialect/config.go

@@ -0,0 +1,62 @@
+package dialect
+
+import (
+	"database/sql"
+	"sync"
+)
+
+type Config struct {
+	Dialects map[string]interface{} `mapstructure:",remain"`
+	Dialect  Matcher
+}
+
+type Dialect struct {
+	Matcher   Matcher
+	Config    Connector
+	IsDefault bool
+}
+
+var (
+	dialects       []*Dialect
+	defaultDialect *Dialect
+	dialectsMu     sync.Mutex
+)
+
+type Matcher interface {
+	MatchName(string) bool
+	Decode([]interface{}) (Connector, error)
+}
+
+type Connector interface {
+	Connect(useAdmin bool) (*sql.DB, error)
+	DatabaseName() string
+	Username() string
+	Password() string
+	Type() string
+}
+
+func Register(matcher Matcher, config Connector, isDefault bool) {
+	dialectsMu.Lock()
+	defer dialectsMu.Unlock()
+
+	d := &Dialect{Matcher: matcher, Config: config}
+
+	if isDefault {
+		defaultDialect = d
+		return
+	}
+
+	dialects = append(dialects, d)
+}
+
+func SelectByConfig(config map[string]interface{}) *Dialect {
+	for key := range config {
+		for _, d := range dialects {
+			if d.Matcher.MatchName(key) {
+				return d
+			}
+		}
+	}
+
+	return defaultDialect
+}