Refactor parsing & select order by impl (#6)

Reviewed-on: #6

schema/parser.go

@@ -0,0 +1,103 @@
+package schema
+
+import (
+	"reflect"
+	"strings"
+
+	"git.gdulai.com/gdulai/simpleorm/util"
+	log "gitlab.com/gdulai/simpleloglvl"
+)
+
+type Parser struct {
+	typ         reflect.Type
+	columns     []Column
+	constraints []Constraint
+}
+
+func NewParser[T any](obj T) *Parser {
+	objType := reflect.TypeOf(obj)
+	return &Parser{typ: objType}
+}
+
+// Step 1 of the parsing, it creates the table instance and
+func (p *Parser) ParseColumns() {
+	var columns []Column
+	for field := range p.typ.Fields() {
+		field := field
+		col := NewColumn(util.CamelToSnake((field.Name)), field.Name, determineType(field.Type), field.Tag)
+		columns = append(columns, col)
+	}
+	p.columns = columns
+}
+
+// Step 2 of the parsing, it creates the constrains with the table references
+func (p *Parser) ParseConstraints(tableParsers map[string]*Parser) {
+	pkConstraint := Constraint{Name: "pk_" + strings.ToLower(util.CamelToSnake((p.typ.Name()))), Type: "pk"}
+	fkConstraints := make(map[string]Constraint)
+	for _, col := range p.columns {
+		_, ok := col.Modifiers["pk"]
+		if ok {
+			pkConstraint.Columns = append(pkConstraint.Columns, col)
+			continue
+		}
+
+		fkMod, ok := col.Modifiers["fk"]
+		if !ok {
+			continue
+		}
+
+		fkModParts := strings.Split(fkMod, ".")
+		refTypeName := fkModParts[0]
+		refTableName := util.CamelToSnake(refTypeName)
+		parser, ok := tableParsers[refTypeName]
+		if !ok {
+			log.LogError("[ORM] Reference table not found", refTypeName)
+		}
+
+		fkId, ok := col.Modifiers["fk_id"]
+		if fkId == "" {
+			fkId = "fk_" + strings.ToLower(refTableName)
+		}
+
+		fkConstraint, ok := fkConstraints[fkId]
+		if !ok {
+			fkConstraint = Constraint{Name: fkId, Type: "fk", RefTypeName: refTypeName}
+		}
+
+		fkConstraint.Columns = append(fkConstraint.Columns, col)
+
+		refField := fkModParts[1]
+		for _, refC := range parser.columns {
+			if refC.FieldName == refField {
+				fkConstraint.RefColumns = append(fkConstraint.RefColumns, refC)
+			}
+		}
+
+		fkConstraints[fkId] = fkConstraint
+	}
+
+	p.constraints = append(p.constraints, pkConstraint)
+	for _, fkConstraint := range fkConstraints {
+		p.constraints = append(p.constraints, fkConstraint)
+	}
+}
+
+// Step 3 of the paring, create the schema.Table instance
+// Returns the schema.Table pointer
+func (p Parser) ParseTable() *Table {
+	return &Table{name: util.CamelToSnake(p.typ.Name()), typ: p.typ, columns: p.columns, constraints: p.constraints}
+}
+
+func determineType(typ reflect.Type) string {
+	typStr := typ.String()
+	switch typStr {
+	case "string":
+		return "TEXT"
+	case "int", "bool":
+		return "INTEGER"
+	case "time.Time", "int64":
+		return "BIGINT"
+	}
+
+	return "VARCHAR(255)"
+}