Add initial declpac CLI tool implementation

pkg/validation/validation.go

@@ -0,0 +1,74 @@
+package validation
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"time"
+)
+
+var LockFile = "/var/lib/pacman/db.lock"
+
+func Validate(packages []string) error {
+	if len(packages) == 0 {
+		return errors.New("no packages found")
+	}
+
+	if err := checkDBFreshness(); err != nil {
+		return err
+	}
+
+	if err := validatePackages(packages); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func checkDBFreshness() error {
+	info, err := os.Stat(LockFile)
+	if err != nil {
+		return nil
+	}
+
+	age := time.Since(info.ModTime())
+	if age > 24*time.Hour {
+		cmd := exec.Command("pacman", "-Syy")
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		if err := cmd.Run(); err != nil {
+			return fmt.Errorf("failed to refresh pacman database: %w", err)
+		}
+	}
+
+	return nil
+}
+
+func validatePackages(packages []string) error {
+	for _, pkg := range packages {
+		if err := validatePackage(pkg); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func validatePackage(name string) error {
+	cmd := exec.Command("pacman", "-Qip", name)
+	if err := cmd.Run(); err == nil {
+		return nil
+	}
+
+	cmd = exec.Command("pacman", "-Sip", name)
+	if err := cmd.Run(); err == nil {
+		return nil
+	}
+
+	cmd = exec.Command("aur", "search", name)
+	if out, err := cmd.Output(); err == nil && len(out) > 0 {
+		return nil
+	}
+
+	return fmt.Errorf("package not found: %s", name)
+}