added create index sql parser

tools/dbutils/index.go

@@ -0,0 +1,106 @@
+package dbutils
+
+import (
+	"regexp"
+	"strings"
+
+	"github.com/pocketbase/pocketbase/tools/tokenizer"
+)
+
+var (
+	indexRegex       = regexp.MustCompile(`(?im)create\s+(unique\s+)?\s*index\s*(if\s+not\s+exists\s+)?([\w\"\'\[\]\.]*)\s+on\s+([\w\"\'\[\]\.]*)\s+\(([\s\S]*)\)(?:\s*where\s+([\s\S]*))?`)
+	indexColumnRegex = regexp.MustCompile(`(?im)^([\s\S]+?)(?:\s+collate\s+([\w]+))?(?:\s+(asc|desc))?$`)
+)
+
+// IndexColumn represents a single parsed SQL index column.
+type IndexColumn struct {
+	Name    string `json:"name"` // identifier or expression
+	Collate string `json:"collate"`
+	Sort    string `json:"sort"`
+}
+
+// Index represents a single parsed SQL CREATE INDEX expression.
+type Index struct {
+	Unique     bool          `json:"unique"`
+	Optional   bool          `json:"optional"`
+	SchemaName string        `json:"schemaName"`
+	IndexName  string        `json:"indexName"`
+	TableName  string        `json:"tableName"`
+	Columns    []IndexColumn `json:"columns"`
+	Where      string        `json:"where"`
+}
+
+// IsValid checks if the current Index contains the minimum required fields to be considered valid.
+func (idx Index) IsValid() bool {
+	return idx.IndexName != "" && idx.TableName != "" && len(idx.Columns) > 0
+}
+
+// ParseIndex parses the provided `CREATE INDEX` SQL string into Index struct.
+func ParseIndex(createIndexExpr string) Index {
+	result := Index{}
+
+	matches := indexRegex.FindStringSubmatch(createIndexExpr)
+	if len(matches) != 7 {
+		return result
+	}
+
+	trimChars := "`\"'[]\r\n\t\f\v "
+
+	// Unique
+	// ---
+	result.Unique = strings.TrimSpace(matches[1]) != ""
+
+	// Optional (aka. "IF NOT EXISTS")
+	// ---
+	result.Optional = strings.TrimSpace(matches[2]) != ""
+
+	// SchemaName and IndexName
+	// ---
+	nameTk := tokenizer.NewFromString(matches[3])
+	nameTk.Separators('.')
+
+	nameParts, _ := nameTk.ScanAll()
+	if len(nameParts) == 2 {
+		result.SchemaName = strings.Trim(nameParts[0], trimChars)
+		result.IndexName = strings.Trim(nameParts[1], trimChars)
+	} else {
+		result.IndexName = strings.Trim(nameParts[0], trimChars)
+	}
+
+	// TableName
+	// ---
+	result.TableName = strings.Trim(matches[4], trimChars)
+
+	// Columns
+	// ---
+	columnsTk := tokenizer.NewFromString(matches[5])
+	columnsTk.Separators(',')
+
+	rawColumns, _ := columnsTk.ScanAll()
+
+	result.Columns = make([]IndexColumn, 0, len(rawColumns))
+
+	for _, col := range rawColumns {
+		colMatches := indexColumnRegex.FindStringSubmatch(col)
+		if len(colMatches) != 4 {
+			continue
+		}
+
+		trimmedName := strings.Trim(colMatches[1], trimChars)
+		if trimmedName == "" {
+			continue
+		}
+
+		result.Columns = append(result.Columns, IndexColumn{
+			Name:    trimmedName,
+			Collate: strings.TrimSpace(colMatches[2]),
+			Sort:    strings.ToUpper(colMatches[3]),
+		})
+	}
+
+	// WHERE expression
+	// ---
+	result.Where = strings.TrimSpace(matches[6])
+
+	return result
+}