1 files changed, 124 insertions, 0 deletions
diff --git a/file.go b/file.go
new file mode 100644
index 0000000..ecf8932
--- /dev/null
+++ b/file.go
@@ -0,0 +1,124 @@
+package migrate
+
+import (
+	"database/sql"
+	"fmt"
+	"io/ioutil"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"regexp"
+	"strconv"
+)
+
+// Regex matches the following pattern:
+// 123_name.ext
+var validFilename = regexp.MustCompile(`^([0-9]+)_(.*)\.(.*)$`)
+
+// Just the path to the migration file
+type fileMigration string
+
+// NewFileMigrator creates a new set of migrations from a path
+// Each one is run in a transaction.
+func NewFileMigrator(db *sql.DB, path string, opts ...Option) (*Migrator, error) {
+	migrations, err := readFiles(path)
+	if err != nil {
+		return nil, err
+	}
+
+	m := Migrator{db: db, migrations: migrations}
+
+	for _, opt := range opts {
+		if err = opt(&m); err != nil {
+			return nil, err
+		}
+	}
+
+	return &m, nil
+}
+
+// The Version is extracted from the filename
+// It implements the Migration interface
+func (fm fileMigration) Version() int64 {
+	m := validFilename.FindStringSubmatch(path.Base(string(fm)))
+	if len(m) == 4 {
+		if version, err := strconv.ParseInt(m[1], 10, 64); err == nil {
+			return version
+		}
+	}
+	return -1
+}
+
+// Run executes the migration
+// It implements the Migration interface
+func (fm fileMigration) Run(tx *sql.Tx) error {
+	r, err := os.Open(string(fm))
+	if err != nil {
+		return err
+	}
+	defer r.Close()
+
+	buf, err := ioutil.ReadAll(r)
+	if err != nil {
+		return err
+	}
+	_, err = tx.Exec(string(buf[:]))
+	return err
+}
+
+// Read all files in path
+// They will be sorted by the migrator according to Version()
+func readFiles(uri string) (migrations []Migration, err error) {
+	u, err := url.Parse(uri)
+	if err != nil {
+		return nil, err
+	}
+
+	// Host might be `.`
+	p := u.Host + u.Path
+
+	if len(p) == 0 {
+		// Default to current directory
+		wd, err := os.Getwd()
+		if err != nil {
+			return nil, err
+		}
+		p = wd
+	} else if p[0:1] == "." || p[0:1] != "/" {
+		// Ensure path is absolute
+		abs, err := filepath.Abs(p)
+		if err != nil {
+			return nil, err
+		}
+		p = abs
+	}
+
+	// Scan entire directory
+	files, err := ioutil.ReadDir(p)
+	if err != nil {
+		return nil, err
+	}
+
+	seen := make(map[int64]bool)
+
+	for _, fi := range files {
+		if !fi.IsDir() {
+			fm := fileMigration(path.Join(p, fi.Name()))
+
+			// Ignore invalid filenames
+			v := fm.Version()
+			if v == -1 {
+				fmt.Printf("invalid version %d for %s\n", v, fm)
+				continue
+			}
+			if seen[v] {
+				fmt.Printf("duplicate version %d for %s\n", v, fm)
+				continue
+			}
+			migrations = append(migrations, fm)
+			seen[v] = true
+		}
+	}
+	return migrations, nil
+}