vibe coded the shit out of a db migration system

internal/backup/backup.go

@@ -0,0 +1,133 @@
+package backup
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"sort"
+	"time"
+
+	"git.haelnorr.com/h/oslstats/internal/config"
+	"github.com/pkg/errors"
+)
+
+// CreateBackup creates a compressed PostgreSQL dump before migrations
+// Returns backup filename and error
+// If pg_dump is not available, returns nil error with warning
+func CreateBackup(ctx context.Context, cfg *config.Config, operation string) (string, error) {
+	// Check if pg_dump is available
+	if _, err := exec.LookPath("pg_dump"); err != nil {
+		fmt.Println("[WARN] pg_dump not found - skipping backup")
+		fmt.Println("[WARN] Install PostgreSQL client tools for automatic backups:")
+		fmt.Println("[WARN]   Ubuntu/Debian: sudo apt-get install postgresql-client")
+		fmt.Println("[WARN]   macOS: brew install postgresql")
+		fmt.Println("[WARN]   Arch: sudo pacman -S postgresql-libs")
+		return "", nil // Don't fail, just warn
+	}
+
+	// Ensure backup directory exists
+	if err := os.MkdirAll(cfg.DB.BackupDir, 0755); err != nil {
+		return "", errors.Wrap(err, "failed to create backup directory")
+	}
+
+	// Generate filename: YYYYMMDD_HHmmss_pre_{operation}.sql.gz
+	timestamp := time.Now().Format("20060102_150405")
+	filename := filepath.Join(cfg.DB.BackupDir,
+		fmt.Sprintf("%s_pre_%s.sql.gz", timestamp, operation))
+
+	// Check if gzip is available
+	useGzip := true
+	if _, err := exec.LookPath("gzip"); err != nil {
+		fmt.Println("[WARN] gzip not found - using uncompressed backup")
+		useGzip = false
+		filename = filepath.Join(cfg.DB.BackupDir,
+			fmt.Sprintf("%s_pre_%s.sql", timestamp, operation))
+	}
+
+	// Build pg_dump command
+	var cmd *exec.Cmd
+	if useGzip {
+		// Use shell to pipe pg_dump through gzip
+		pgDumpCmd := fmt.Sprintf(
+			"pg_dump -h %s -p %d -U %s -d %s --no-owner --no-acl --clean --if-exists | gzip > %s",
+			cfg.DB.Host,
+			cfg.DB.Port,
+			cfg.DB.User,
+			cfg.DB.DB,
+			filename,
+		)
+		cmd = exec.CommandContext(ctx, "sh", "-c", pgDumpCmd)
+	} else {
+		cmd = exec.CommandContext(ctx, "pg_dump",
+			"-h", cfg.DB.Host,
+			"-p", fmt.Sprint(cfg.DB.Port),
+			"-U", cfg.DB.User,
+			"-d", cfg.DB.DB,
+			"-f", filename,
+			"--no-owner",
+			"--no-acl",
+			"--clean",
+			"--if-exists",
+		)
+	}
+
+	// Set password via environment variable
+	cmd.Env = append(os.Environ(),
+		fmt.Sprintf("PGPASSWORD=%s", cfg.DB.Password))
+
+	// Run backup
+	if err := cmd.Run(); err != nil {
+		return "", errors.Wrap(err, "pg_dump failed")
+	}
+
+	// Get file size for logging
+	info, err := os.Stat(filename)
+	if err != nil {
+		return filename, errors.Wrap(err, "stat backup file")
+	}
+
+	sizeMB := float64(info.Size()) / 1024 / 1024
+	fmt.Printf("[INFO] Backup created: %s (%.2f MB)\n", filename, sizeMB)
+
+	return filename, nil
+}
+
+// CleanOldBackups keeps only the N most recent backups
+func CleanOldBackups(cfg *config.Config, keepCount int) error {
+	// Get all backup files (both .sql and .sql.gz)
+	sqlFiles, err := filepath.Glob(filepath.Join(cfg.DB.BackupDir, "*.sql"))
+	if err != nil {
+		return errors.Wrap(err, "failed to list .sql backups")
+	}
+
+	gzFiles, err := filepath.Glob(filepath.Join(cfg.DB.BackupDir, "*.sql.gz"))
+	if err != nil {
+		return errors.Wrap(err, "failed to list .sql.gz backups")
+	}
+
+	files := append(sqlFiles, gzFiles...)
+
+	if len(files) <= keepCount {
+		return nil // Nothing to clean
+	}
+
+	// Sort files by modification time (newest first)
+	sort.Slice(files, func(i, j int) bool {
+		iInfo, _ := os.Stat(files[i])
+		jInfo, _ := os.Stat(files[j])
+		return iInfo.ModTime().After(jInfo.ModTime())
+	})
+
+	// Delete old backups
+	for i := keepCount; i < len(files); i++ {
+		if err := os.Remove(files[i]); err != nil {
+			fmt.Printf("[WARN] Failed to remove old backup %s: %v\n", files[i], err)
+		} else {
+			fmt.Printf("[INFO] Removed old backup: %s\n", filepath.Base(files[i]))
+		}
+	}
+
+	return nil
+}