Add connection string builder

connection_string.go

@@ -0,0 +1,81 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"os/user"
+	"strings"
+)
+
+func formatConnectionUrl(opts Options) (string, error) {
+	url := opts.Url
+
+	// Make sure to only accept urls in a standard format
+	if !strings.Contains(url, "postgres://") {
+		return "", errors.New("Invalid URL. Valid format: postgres://user:password@host:port/db?sslmode=mode")
+	}
+
+	// Special handling for local connections
+	if strings.Contains(url, "localhost") || strings.Contains(url, "127.0.0.1") {
+		if !strings.Contains(url, "?sslmode") {
+			if opts.Ssl == "" {
+				url += fmt.Sprintf("?sslmode=%s", "disable")
+			} else {
+				url += fmt.Sprintf("?sslmode=%s", opts.Ssl)
+			}
+		}
+	}
+
+	// Append sslmode parameter only if its defined as a flag and not present
+	// in the connection string.
+	if !strings.Contains(url, "?sslmode") && opts.Ssl != "" {
+		url += fmt.Sprintf("?sslmode=%s", opts.Ssl)
+	}
+
+	return url, nil
+}
+
+func buildConnectionString(opts Options) (string, error) {
+	if opts.Url != "" {
+		return formatConnectionUrl(opts)
+	}
+
+	// Try to detect user from current OS user
+	// TODO: remove os/user dependency
+	if opts.User == "" {
+		user, err := user.Current()
+
+		if err == nil {
+			opts.User = user.Username
+		}
+	}
+
+	// Disable ssl for localhost connections, most users have it disabled
+	if opts.Host == "localhost" || opts.Host == "127.0.0.1" {
+		if opts.Ssl == "" {
+			opts.Ssl = "disable"
+		}
+	}
+
+	url := "postgres://"
+
+	if opts.User != "" {
+		url += opts.User
+	}
+
+	if opts.Pass != "" {
+		url += fmt.Sprintf(":%s", opts.Pass)
+	}
+
+	url += fmt.Sprintf("@%s:%d", opts.Host, opts.Port)
+
+	if opts.DbName != "" {
+		url += fmt.Sprintf("/%s", opts.DbName)
+	}
+
+	if opts.Ssl != "" {
+		url += fmt.Sprintf("?sslmode=%s", opts.Ssl)
+	}
+
+	return url, nil
+}