feat: establish Orbit models, migrations and development baseline

internal/storage/mysql/sqlsplit.go

@@ -0,0 +1,99 @@
+package mysql
+
+import (
+	"errors"
+	"strings"
+)
+
+// splitSQL supports ordinary migration statements, quoted values and comments.
+// Stored routines and DELIMITER scripts are intentionally unsupported.
+func splitSQL(src string) ([]string, error) {
+	var out []string
+	var b strings.Builder
+	var quote byte
+	lineComment, blockComment := false, false
+	flush := func() error {
+		s := strings.TrimSpace(b.String())
+		b.Reset()
+		if s == "" {
+			return nil
+		}
+		if strings.HasPrefix(strings.ToUpper(s), "DELIMITER") {
+			return errors.New("DELIMITER scripts are unsupported")
+		}
+		out = append(out, s)
+		return nil
+	}
+	for i := 0; i < len(src); i++ {
+		c := src[i]
+		if lineComment {
+			if c == '\n' {
+				lineComment = false
+				b.WriteByte(' ')
+			}
+			continue
+		}
+		if blockComment {
+			if c == '*' && i+1 < len(src) && src[i+1] == '/' {
+				blockComment = false
+				i++
+				b.WriteByte(' ')
+			}
+			continue
+		}
+		if quote != 0 {
+			b.WriteByte(c)
+			if c == '\\' && i+1 < len(src) {
+				i++
+				b.WriteByte(src[i])
+				continue
+			}
+			if c == quote {
+				if i+1 < len(src) && src[i+1] == quote {
+					i++
+					b.WriteByte(src[i])
+				} else {
+					quote = 0
+				}
+			}
+			continue
+		}
+		if c == '#' || c == '-' && i+2 < len(src) && src[i+1] == '-' && src[i+2] <= ' ' {
+			lineComment = true
+			if c == '-' {
+				i++
+			}
+			continue
+		}
+		if c == '/' && i+1 < len(src) && src[i+1] == '*' {
+			if i+2 < len(src) && src[i+2] == '!' {
+				return nil, errors.New("executable SQL comments are unsupported")
+			}
+			blockComment = true
+			i++
+			continue
+		}
+		if c == '\'' || c == '"' || c == '`' {
+			quote = c
+			b.WriteByte(c)
+			continue
+		}
+		if c == ';' {
+			if err := flush(); err != nil {
+				return nil, err
+			}
+			continue
+		}
+		b.WriteByte(c)
+	}
+	if quote != 0 || blockComment {
+		return nil, errors.New("unterminated SQL quote or comment")
+	}
+	if err := flush(); err != nil {
+		return nil, err
+	}
+	if len(out) == 0 {
+		return nil, errors.New("empty migration")
+	}
+	return out, nil
+}