diff --git a/.codeclimate.yml b/.codeclimate.yml
deleted file mode 100644
index baf8a21..0000000
--- a/.codeclimate.yml
+++ /dev/null
@@ -1,13 +0,0 @@
-version: "2"
-
-exclude_patterns:
-- "**/autogenerated_*"
-- "**/vendor/"
-
-checks:
-  file-lines:
-    config:
-      threshold: 400
-  method-lines:
-    config:
-      threshold: 100
diff --git a/.gitignore b/.gitignore
index db181c1..9886722 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,3 @@
 /go-queryset
 /vendor
+/internal/parser/test/tmptestdir*/
diff --git a/.golangci.yml b/.golangci.yml
new file mode 100644
index 0000000..1d70599
--- /dev/null
+++ b/.golangci.yml
@@ -0,0 +1,37 @@
+run:
+  skip-dirs:
+    - ^internal/parser/test/tmptestdir.*
+
+linters-settings:
+  govet:
+    check-shadowing: true
+  golint:
+    min-confidence: 0
+  gocyclo:
+    min-complexity: 15
+  goconst:
+    min-len: 2
+    min-occurrences: 2
+  lll:
+    line-length: 140
+
+linters:
+  enable-all: true
+  disable:
+    - scopelint
+    - gochecknoglobals
+    - gosec
+
+issues:
+  exclude-rules:
+    - linters:
+        - unparam
+      text: always receives
+    - linters:
+        - staticcheck
+      text: "SA9003:"
+
+# golangci.com configuration
+# https://github.com/golangci/golangci/wiki/Configuration
+# service:
+#   golangci-lint-version: 1.14.0 # use fixed version to not introduce new linters unexpectedly
diff --git a/.travis.yml b/.travis.yml
index c0119a5..dd3f0f1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,13 +1,10 @@
 language: go
 go:
-  - 1.8.x
-  - 1.9.x
+  - 1.11.x
+  - 1.12.x
 before_install:
   - go get github.com/mattn/goveralls
-  - go get github.com/alecthomas/gometalinter
-  - go get github.com/golang/dep/cmd/dep
-  - dep ensure -v
-  - gometalinter --install --vendored-linters
+  - curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.15.0
 script:
   - make test
-  - $HOME/gopath/bin/goveralls -ignore "queryset/test/autogenerated_models.go,examples/comparison/*/*.go,queryset/test/pkgimport/*.go,queryset/test/pkgimport/*/*/*.go" -v -service=travis-ci
+  - $HOME/gopath/bin/goveralls -ignore "internal/queryset/generator/test/autogenerated_models.go,examples/comparison/*/*.go,internal/queryset/generator/test/pkgimport/*.go,internal/queryset/generator/test/pkgimport/*/*/*.go" -v -service=travis-ci
diff --git a/Makefile b/Makefile
index 1559649..1b701d9 100644
--- a/Makefile
+++ b/Makefile
@@ -1,24 +1,14 @@
 test_static:
-	go install ./...
-	gometalinter --vendor --enable-all --min-confidence=0.3 --line-length=120 \
-		-e "parameter \w+ always receives" \
-		-e "/jinzhu/gorm/" \
-		-e "model is unused" \
-		-e '"expections" is a misspelling of "exceptions"' \
-		-e "autogenerated_" \
-		-e "should have comment" \
-		-e "examples/comparison/" \
-		--deadline=5m \
-		./...
+	golangci-lint run
 
 test_unit: test_gen
 	mkdir -p test
-	go test -v ./parser/ ./queryset/ ./queryset/methods/
+	go test -v ./...
 
 AUTOGEN_FILES = \
-	./queryset/test/autogenerated_models.go \
+	./internal/queryset/generator/test/autogenerated_models.go \
 	./examples/comparison/gorm4/autogenerated_gorm4.go \
-	./queryset/test/pkgimport/autogenerated_models.go
+	./internal/queryset/generator/test/pkgimport/autogenerated_models.go
 
 test_gen: gen
 	@- $(foreach F,$(AUTOGEN_FILES), \
@@ -28,7 +18,7 @@ test_gen: gen
 test: test_unit bench test_static
 
 bench:
-	go test -bench=. -benchtime=1s -v -run=^$$ ./queryset/
+	go test -bench=. -benchtime=1s -v -run=^$$ ./internal/queryset/generator/
 
 gen:
 	@- $(foreach F,$(AUTOGEN_FILES), \
diff --git a/cmd/goqueryset/goqueryset.go b/cmd/goqueryset/goqueryset.go
index 350bf8e..8b5321c 100644
--- a/cmd/goqueryset/goqueryset.go
+++ b/cmd/goqueryset/goqueryset.go
@@ -1,20 +1,36 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"log"
-	"strings"
+	"path/filepath"
+	"time"
 
-	"github.com/jirfag/go-queryset/queryset"
+	"github.com/jirfag/go-queryset/internal/parser"
+	"github.com/jirfag/go-queryset/internal/queryset/generator"
 )
 
 func main() {
+	const defaultOutPath = "autogenerated_{in}"
+
 	inFile := flag.String("in", "models.go", "path to input file")
-	outFile := flag.String("out", "autogenerated_{in}", "path to output file")
+	outFile := flag.String("out", defaultOutPath, "path to output file")
+	timeout := flag.Duration("timeout", time.Minute, "timeout for generation")
 	flag.Parse()
 
-	*outFile = strings.Replace(*outFile, "{in}", *inFile, 1)
-	if err := queryset.GenerateQuerySets(*inFile, *outFile); err != nil {
+	if *outFile == defaultOutPath {
+		*outFile = filepath.Join(filepath.Dir(*inFile), "autogenerated_"+filepath.Base(*inFile))
+	}
+
+	g := generator.Generator{
+		StructsParser: &parser.Structs{},
+	}
+
+	ctx, finish := context.WithTimeout(context.Background(), *timeout)
+	defer finish()
+
+	if err := g.Generate(ctx, *inFile, *outFile); err != nil {
 		log.Fatalf("can't generate query sets: %s", err)
 	}
 }
diff --git a/parser/parser.go b/internal/parser/parser.go
similarity index 57%
rename from parser/parser.go
rename to internal/parser/parser.go
index 8609133..598ca46 100644
--- a/parser/parser.go
+++ b/internal/parser/parser.go
@@ -1,17 +1,19 @@
 package parser
 
 import (
+	"context"
 	"fmt"
 	"go/ast"
 	"go/parser"
 	"go/token"
 	"go/types"
-	"os"
 	"path/filepath"
 	"reflect"
 	"strings"
 
-	"golang.org/x/tools/go/loader"
+	"github.com/pkg/errors"
+
+	"golang.org/x/tools/go/packages"
 )
 
 // StructField represents one field in struct
@@ -33,9 +35,6 @@ func (sf StructField) Tag() reflect.StructTag {
 	return sf.tag
 }
 
-// ParsedStructs is a map from struct type name to list of fields
-type ParsedStructs map[string]ParsedStruct
-
 // ParsedStruct represents struct info
 type ParsedStruct struct {
 	TypeName string
@@ -43,47 +42,79 @@ type ParsedStruct struct {
 	Doc      *ast.CommentGroup // line comments; or nil
 }
 
-func fileNameToPkgName(filePath, absFilePath string) string {
-	dir := filepath.Dir(absFilePath)
-	gopathEnv := os.Getenv("GOPATH")
-	gopaths := strings.Split(gopathEnv, string(os.PathListSeparator))
-	var inGoPath string
-	for _, gopath := range gopaths {
-		if strings.HasPrefix(dir, gopath) {
-			inGoPath = gopath
-			break
-		}
-	}
-	if inGoPath == "" {
-		// not in GOPATH
-		return "./" + filepath.Dir(filePath)
-	}
-	r := strings.TrimPrefix(dir, inGoPath)
-	r = strings.TrimPrefix(r, "/")  // may be and may not be
-	r = strings.TrimPrefix(r, "\\") // may be and may not be
-	r = strings.TrimPrefix(r, "src/")
-	r = strings.TrimPrefix(r, "src\\")
-	return r
+type Result struct {
+	Structs     map[string]ParsedStruct
+	PackageName string
+	Types       *types.Package
 }
 
-func typeCheckFuncBodies(path string) bool {
-	return false // don't type-check func bodies to speedup parsing
-}
+type Structs struct{}
 
-func loadProgramFromPackage(pkgFullName string) (*loader.Program, error) {
-	// The loader loads a complete Go program from source code.
-	conf := loader.Config{
-		ParserMode:          parser.ParseComments,
-		TypeCheckFuncBodies: typeCheckFuncBodies,
+func (p Structs) ParseFile(ctx context.Context, filePath string) (*Result, error) {
+	absFilePath, err := filepath.Abs(filePath)
+	if err != nil {
+		return nil, errors.Wrapf(err, "can't get abs path for %s", filePath)
 	}
-	conf.Import(pkgFullName)
-	lprog, err := conf.Load()
+
+	neededStructs, err := p.getStructNamesInFile(absFilePath)
 	if err != nil {
-		return nil, fmt.Errorf("can't load program from package %q: %s",
-			pkgFullName, err)
+		return nil, errors.Wrap(err, "can't get struct names")
+	}
+
+	// need load the full package type info because
+	// some deps can be in other files
+	inPkgName := filepath.Dir(filePath)
+	if !filepath.IsAbs(inPkgName) && !strings.HasPrefix(inPkgName, ".") {
+		// to make this dir name a local package name
+		// can't use filepath.Join because it calls Clean and removes "."+sep
+		inPkgName = fmt.Sprintf(".%c%s", filepath.Separator, inPkgName)
+	}
+
+	pkgs, err := packages.Load(&packages.Config{
+		Mode:    packages.LoadAllSyntax,
+		Context: ctx,
+		Tests:   false,
+	}, inPkgName)
+	if err != nil {
+		return nil, errors.Wrapf(err, "failed to load package for file %s", filePath)
+	}
+
+	if len(pkgs) != 1 {
+		return nil, fmt.Errorf("got too many (%d) packages: %#v", len(pkgs), pkgs)
+	}
+
+	structs := p.buildParsedStructs(pkgs[0], neededStructs)
+	return &Result{
+		Structs:     structs,
+		PackageName: pkgs[0].Name,
+		Types:       pkgs[0].Types,
+	}, nil
+}
+
+func (p Structs) buildParsedStructs(pkg *packages.Package, neededStructs structNamesInfo) map[string]ParsedStruct {
+	ret := map[string]ParsedStruct{}
+
+	scope := pkg.Types.Scope()
+	for _, name := range scope.Names() {
+		obj := scope.Lookup(name)
+
+		if neededStructs[name] == nil {
+			continue
+		}
+
+		t := obj.Type().(*types.Named)
+		s := t.Underlying().(*types.Struct)
+
+		parsedStruct := parseStruct(s, neededStructs[name])
+		if parsedStruct != nil {
+			parsedStruct.TypeName = name
+			ret[name] = *parsedStruct
+		} else {
+			// TODO
+		}
 	}
 
-	return lprog, nil
+	return ret
 }
 
 type structNamesInfo map[string]*ast.GenDecl
@@ -106,7 +137,7 @@ func (v *structNamesVisitor) Visit(n ast.Node) (w ast.Visitor) {
 	return v
 }
 
-func getStructNamesInFile(fname string) (structNamesInfo, error) {
+func (p Structs) getStructNamesInFile(fname string) (structNamesInfo, error) {
 	fset := token.NewFileSet()
 	f, err := parser.ParseFile(fset, fname, nil, parser.ParseComments)
 	if err != nil {
@@ -120,53 +151,6 @@ func getStructNamesInFile(fname string) (structNamesInfo, error) {
 	return v.names, nil
 }
 
-// GetStructsInFile lists all structures in file passed and returns them with all fields
-func GetStructsInFile(filePath string) (*loader.PackageInfo, ParsedStructs, error) {
-	absFilePath, err := filepath.Abs(filePath)
-	if err != nil {
-		return nil, nil, fmt.Errorf("can't get abs path for %s", filePath)
-	}
-
-	neededStructs, err := getStructNamesInFile(absFilePath)
-	if err != nil {
-		return nil, nil, fmt.Errorf("can't get struct names: %s", err)
-	}
-
-	packageFullName := fileNameToPkgName(filePath, absFilePath)
-	lprog, err := loadProgramFromPackage(packageFullName)
-	if err != nil {
-		return nil, nil, err
-	}
-
-	pkgInfo := lprog.Package(packageFullName)
-	if pkgInfo == nil {
-		return nil, nil, fmt.Errorf("can't load types for file %s in package %q",
-			filePath, packageFullName)
-	}
-
-	ret := ParsedStructs{}
-
-	scope := pkgInfo.Pkg.Scope()
-	for _, name := range scope.Names() {
-		obj := scope.Lookup(name)
-
-		if neededStructs[name] == nil {
-			continue
-		}
-
-		t := obj.Type().(*types.Named)
-		s := t.Underlying().(*types.Struct)
-
-		parsedStruct := parseStruct(s, neededStructs[name])
-		if parsedStruct != nil {
-			parsedStruct.TypeName = name
-			ret[name] = *parsedStruct
-		}
-	}
-
-	return pkgInfo, ret, nil
-}
-
 func newStructField(f *types.Var, tag string) *StructField {
 	return &StructField{
 		name: f.Name(),
diff --git a/parser/parser_test.go b/internal/parser/parser_test.go
similarity index 86%
rename from parser/parser_test.go
rename to internal/parser/parser_test.go
index 0a0c9c6..ff0fe9f 100644
--- a/parser/parser_test.go
+++ b/internal/parser/parser_test.go
@@ -1,6 +1,7 @@
 package parser
 
 import (
+	"context"
 	"crypto/rand"
 	"encoding/hex"
 	"fmt"
@@ -9,7 +10,6 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
-	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -30,23 +30,7 @@ func getRepoRoot() string {
 }
 
 func getTempDirRoot() string {
-	return filepath.Join(getRepoRoot(), "test")
-}
-
-func TestFileNameToPkgName(t *testing.T) {
-	_, selfFilePath, _, ok := runtime.Caller(0)
-	assert.True(t, ok)
-	assert.NotEmpty(t, selfFilePath)
-	selfPkg := "github.com/jirfag/go-queryset/parser"
-	if !strings.Contains(selfFilePath, selfPkg) {
-		t.Skipf("it's a forked repo %q, skip pkg path test", selfFilePath)
-	}
-
-	assert.Equal(t, selfPkg, fileNameToPkgName("", selfFilePath))
-
-	const fileNotInGoPath = "models/models.go"
-	const absFileNotInGoPath = "/tmp/" + fileNotInGoPath
-	assert.Equal(t, "./models", fileNameToPkgName(fileNotInGoPath, absFileNotInGoPath))
+	return filepath.Join(getRepoRoot(), "parser", "test")
 }
 
 func getTempFileName(rootDir, prefix, suffix string) (*os.File, error) {
@@ -123,6 +107,7 @@ func TestGetStructNamesInFile(t *testing.T) {
 		},
 	}
 
+	p := Structs{}
 	for i, tc := range cases {
 		tc := tc // capture range variable
 		t.Run(fmt.Sprintf("case %d", i), func(t *testing.T) {
@@ -130,7 +115,7 @@ func TestGetStructNamesInFile(t *testing.T) {
 			f := getTmpFileForCode(tc.code)
 			defer removeTempFileAndDir(f)
 
-			res, err := getStructNamesInFile(f.Name())
+			res, err := p.getStructNamesInFile(f.Name())
 			if tc.errorIsExpected {
 				assert.NotNil(t, err)
 				return
@@ -267,24 +252,24 @@ func testStructFields(t *testing.T, tc structFieldsCase) {
 	f := getTmpFileForCode(tc.code)
 	defer removeTempFileAndDir(f)
 
-	pkg, structs, err := GetStructsInFile(f.Name())
+	p := Structs{}
+	ret, err := p.ParseFile(context.Background(), f.Name())
 	if tc.errorIsExpected {
 		assert.NotNil(t, err)
 		return
 	}
 
 	assert.Nil(t, err)
-	assert.NotNil(t, pkg)
-	assert.NotNil(t, structs)
+	assert.NotNil(t, ret)
 
-	assert.Len(t, structs, tc.getExpectedtructsCount())
+	assert.Len(t, ret.Structs, tc.getExpectedtructsCount())
 	if tc.getExpectedtructsCount() == 0 {
 		return
 	}
 
 	var typeName string
 
-	for structTypeName := range structs {
+	for structTypeName := range ret.Structs {
 		if structTypeName == "T" {
 			typeName = structTypeName
 			break
@@ -292,7 +277,7 @@ func testStructFields(t *testing.T, tc structFieldsCase) {
 	}
 	assert.NotNil(t, typeName)
 
-	s := structs[typeName]
+	s := ret.Structs[typeName]
 	fieldNames := []string{}
 	for _, field := range s.Fields {
 		assert.NotEmpty(t, field.Name)
diff --git a/parser/test/test.go b/internal/parser/test/test.go
similarity index 100%
rename from parser/test/test.go
rename to internal/parser/test/test.go
diff --git a/queryset/field/field.go b/internal/queryset/field/field.go
similarity index 100%
rename from queryset/field/field.go
rename to internal/queryset/field/field.go
diff --git a/queryset/field/field_test.go b/internal/queryset/field/field_test.go
similarity index 100%
rename from queryset/field/field_test.go
rename to internal/queryset/field/field_test.go
diff --git a/internal/queryset/generator/generator.go b/internal/queryset/generator/generator.go
new file mode 100644
index 0000000..7d4f6bc
--- /dev/null
+++ b/internal/queryset/generator/generator.go
@@ -0,0 +1,103 @@
+package generator
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+
+	"github.com/jirfag/go-queryset/internal/parser"
+	"github.com/pkg/errors"
+	"golang.org/x/tools/imports"
+)
+
+type Generator struct {
+	StructsParser *parser.Structs
+}
+
+// Generate generates output file with querysets
+func (g Generator) Generate(ctx context.Context, inFilePath, outFilePath string) error {
+	parsedFile, err := g.StructsParser.ParseFile(ctx, inFilePath)
+	if err != nil {
+		return errors.Wrapf(err, "can't parse file %s to get structs", inFilePath)
+	}
+
+	var r io.Reader
+	r, err = GenerateQuerySetsForStructs(parsedFile.Types, parsedFile.Structs)
+	if err != nil {
+		return errors.Wrap(err, "can't generate query sets")
+	}
+
+	if r == nil {
+		return fmt.Errorf("no structs to generate query set in %s", inFilePath)
+	}
+
+	if err = g.writeQuerySetsToOutput(r, parsedFile.PackageName, outFilePath); err != nil {
+		return errors.Wrapf(err, "can't save query sets to out file %s", outFilePath)
+	}
+
+	var absOutPath string
+	absOutPath, err = filepath.Abs(outFilePath)
+	if err != nil {
+		absOutPath = outFilePath
+	}
+
+	log.Printf("successfully wrote querysets to %s", absOutPath)
+	return nil
+}
+
+func (g Generator) writeQuerySetsToOutput(r io.Reader, packageName, outFile string) error {
+	const hdrTmpl = `%s
+	package %s
+
+import (
+	"errors"
+	"fmt"
+	"time"
+
+	"github.com/jinzhu/gorm"
+)
+`
+
+	// https://golang.org/s/generatedcode
+	const genHdr = `// Code generated by go-queryset. DO NOT EDIT.`
+
+	var buf bytes.Buffer
+	pkgName := fmt.Sprintf(hdrTmpl, genHdr, packageName)
+	if _, err := buf.WriteString(pkgName); err != nil {
+		return errors.Wrap(err, "can't write hdr string into buf")
+	}
+	if _, err := io.Copy(&buf, r); err != nil {
+		return errors.Wrap(err, "can't write to buf")
+	}
+
+	formattedRes, err := imports.Process(outFile, buf.Bytes(), nil)
+	if err != nil {
+		if os.Getenv("GOQUERYSET_DEBUG_IMPORTS_ERRORS") == "1" {
+			log.Printf("Can't format generated file: %s", err)
+			formattedRes = buf.Bytes()
+		} else {
+			return errors.Wrap(err, "can't format generated file")
+		}
+	}
+
+	var outF *os.File
+	outF, err = os.OpenFile(outFile, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0640) // nolint: gas
+	if err != nil {
+		return fmt.Errorf("can't open out file: %s", err)
+	}
+	defer func() {
+		if e := outF.Close(); e != nil {
+			log.Printf("can't close file: %s", e)
+		}
+	}()
+
+	if _, err = outF.Write(formattedRes); err != nil {
+		return errors.Wrap(err, "can't write to out file")
+	}
+
+	return nil
+}
diff --git a/queryset/methodsbuilder.go b/internal/queryset/generator/methodsbuilder.go
similarity index 95%
rename from queryset/methodsbuilder.go
rename to internal/queryset/generator/methodsbuilder.go
index 64777a3..e0276a5 100644
--- a/queryset/methodsbuilder.go
+++ b/internal/queryset/generator/methodsbuilder.go
@@ -1,9 +1,9 @@
-package queryset
+package generator
 
 import (
-	"github.com/jirfag/go-queryset/parser"
-	"github.com/jirfag/go-queryset/queryset/field"
-	"github.com/jirfag/go-queryset/queryset/methods"
+	"github.com/jirfag/go-queryset/internal/parser"
+	"github.com/jirfag/go-queryset/internal/queryset/field"
+	"github.com/jirfag/go-queryset/internal/queryset/methods"
 )
 
 type methodsBuilder struct {
diff --git a/queryset/queryset.go b/internal/queryset/generator/queryset.go
similarity index 76%
rename from queryset/queryset.go
rename to internal/queryset/generator/queryset.go
index da71685..d9e34e0 100644
--- a/queryset/queryset.go
+++ b/internal/queryset/generator/queryset.go
@@ -1,18 +1,17 @@
-package queryset
+package generator
 
 import (
 	"bytes"
 	"fmt"
 	"go/ast"
+	"go/types"
 	"io"
 	"sort"
 	"strings"
 
-	"golang.org/x/tools/go/loader"
-
-	"github.com/jirfag/go-queryset/parser"
-	"github.com/jirfag/go-queryset/queryset/field"
-	"github.com/jirfag/go-queryset/queryset/methods"
+	"github.com/jirfag/go-queryset/internal/parser"
+	"github.com/jirfag/go-queryset/internal/queryset/field"
+	"github.com/jirfag/go-queryset/internal/queryset/methods"
 )
 
 type querySetStructConfig struct {
@@ -56,8 +55,8 @@ func doesNeedToGenerateQuerySet(doc *ast.CommentGroup) bool {
 	return false
 }
 
-func genStructFieldInfos(s parser.ParsedStruct, pkgInfo *loader.PackageInfo) (ret []field.Info) {
-	g := field.NewInfoGenerator(pkgInfo.Pkg)
+func genStructFieldInfos(s parser.ParsedStruct, types *types.Package) (ret []field.Info) {
+	g := field.NewInfoGenerator(types)
 	for _, f := range s.Fields {
 		fi := g.GenFieldInfo(f)
 		if fi == nil {
@@ -68,8 +67,8 @@ func genStructFieldInfos(s parser.ParsedStruct, pkgInfo *loader.PackageInfo) (re
 	return ret
 }
 
-func generateQuerySetConfigs(pkgInfo *loader.PackageInfo,
-	structs parser.ParsedStructs) querySetStructConfigSlice {
+func generateQuerySetConfigs(types *types.Package,
+	structs map[string]parser.ParsedStruct) querySetStructConfigSlice {
 
 	querySetStructConfigs := querySetStructConfigSlice{}
 
@@ -78,7 +77,7 @@ func generateQuerySetConfigs(pkgInfo *loader.PackageInfo,
 			continue
 		}
 
-		fields := genStructFieldInfos(s, pkgInfo)
+		fields := genStructFieldInfos(s, types)
 		b := newMethodsBuilder(s, fields)
 		methods := b.Build()
 
@@ -97,9 +96,8 @@ func generateQuerySetConfigs(pkgInfo *loader.PackageInfo,
 
 // GenerateQuerySetsForStructs is an internal method to retrieve querysets
 // generated code from parsed structs
-func GenerateQuerySetsForStructs(pkgInfo *loader.PackageInfo, structs parser.ParsedStructs) (io.Reader, error) {
-
-	querySetStructConfigs := generateQuerySetConfigs(pkgInfo, structs)
+func GenerateQuerySetsForStructs(types *types.Package, structs map[string]parser.ParsedStruct) (io.Reader, error) {
+	querySetStructConfigs := generateQuerySetConfigs(types, structs)
 	if len(querySetStructConfigs) == 0 {
 		return nil, nil
 	}
diff --git a/queryset/queryset_test.go b/internal/queryset/generator/queryset_test.go
similarity index 85%
rename from queryset/queryset_test.go
rename to internal/queryset/generator/queryset_test.go
index fd7790c..9dc6e5c 100644
--- a/queryset/queryset_test.go
+++ b/internal/queryset/generator/queryset_test.go
@@ -1,6 +1,7 @@
-package queryset
+package generator
 
 import (
+	"context"
 	"database/sql"
 	"database/sql/driver"
 	"fmt"
@@ -15,14 +16,18 @@ import (
 	"testing"
 	"time"
 
+	"github.com/jirfag/go-queryset/internal/parser"
+
 	"github.com/jinzhu/gorm"
 	_ "github.com/jinzhu/gorm/dialects/mysql"
-	"github.com/jirfag/go-queryset/queryset/test"
-	"github.com/stretchr/testify/assert"
+	"github.com/jirfag/go-queryset/internal/queryset/generator/test"
+	assert "github.com/stretchr/testify/require"
 
-	"gopkg.in/DATA-DOG/go-sqlmock.v1"
+	sqlmock "gopkg.in/DATA-DOG/go-sqlmock.v1"
 )
 
+const testSurname = "Ivanov"
+
 func fixedFullRe(s string) string {
 	return fmt.Sprintf("^%s$", regexp.QuoteMeta(s))
 }
@@ -139,7 +144,7 @@ func TestQueries(t *testing.T) {
 
 func testUserSelectAll(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	expUsers := getTestUsers(2)
-	m.ExpectQuery(fixedFullRe("SELECT * FROM `users` WHERE `users`.deleted_at IS NULL")).
+	m.ExpectQuery(fixedFullRe("SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL")).
 		WillReturnRows(getRowsForUsers(expUsers))
 
 	var users []test.User
@@ -149,7 +154,7 @@ func testUserSelectAll(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 
 func testUserSelectWithLimitAndOffset(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	expUsers := getTestUsers(2)
-	req := "SELECT * FROM `users` WHERE `users`.deleted_at IS NULL LIMIT 1 OFFSET 1"
+	req := "SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL LIMIT 1 OFFSET 1"
 	m.ExpectQuery(fixedFullRe(req)).
 		WillReturnRows(getRowsForUsers(expUsers))
 
@@ -159,7 +164,7 @@ func testUserSelectWithLimitAndOffset(t *testing.T, m sqlmock.Sqlmock, db *gorm.
 }
 
 func testUserSelectAllNoRecords(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
-	m.ExpectQuery(fixedFullRe("SELECT * FROM `users` WHERE `users`.deleted_at IS NULL")).
+	m.ExpectQuery(fixedFullRe("SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL")).
 		WillReturnError(sql.ErrNoRows)
 
 	var users []test.User
@@ -169,7 +174,7 @@ func testUserSelectAllNoRecords(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 
 func testUserSelectOne(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	expUsers := getTestUsers(1)
-	req := "SELECT * FROM `users` WHERE `users`.deleted_at IS NULL ORDER BY `users`.`id` ASC LIMIT 1"
+	req := "SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL ORDER BY `users`.`id` ASC LIMIT 1"
 	m.ExpectQuery(fixedFullRe(req)).
 		WillReturnRows(getRowsForUsers(expUsers))
 
@@ -181,11 +186,11 @@ func testUserSelectOne(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 func testUserSelectWithSurnameFilter(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	expUsers := getTestUsers(1)
 
-	surname := "Ivanov"
+	surname := testSurname
 	expUsers[0].Surname = &surname
 
 	req := "SELECT * FROM `users` " +
-		"WHERE `users`.deleted_at IS NULL AND ((user_surname = ?)) ORDER BY `users`.`id` ASC LIMIT 1"
+		"WHERE `users`.`deleted_at` IS NULL AND ((user_surname = ?)) ORDER BY `users`.`id` ASC LIMIT 1"
 	m.ExpectQuery(fixedFullRe(req)).
 		WillReturnRows(getRowsForUsers(expUsers))
 
@@ -242,7 +247,7 @@ func testUserQueryFilters(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 
 func runUserQueryFilterSubTest(t *testing.T, c userQueryTestCase, m sqlmock.Sqlmock, db *gorm.DB) {
 	expUsers := getTestUsers(5)
-	req := "SELECT * FROM `users` WHERE `users`.deleted_at IS NULL AND " + c.q
+	req := "SELECT * FROM `users` WHERE `users`.`deleted_at` IS NULL AND " + c.q
 	m.ExpectQuery(fixedFullRe(req)).WithArgs(c.args...).
 		WillReturnRows(getRowsForUsers(expUsers))
 
@@ -270,7 +275,7 @@ func testUserCreateOneWithSurname(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB)
 	req := "INSERT INTO `users` (`created_at`,`updated_at`,`deleted_at`,`name`,`user_surname`,`email`) " +
 		"VALUES (?,?,?,?,?,?)"
 
-	surname := "Ivanov"
+	surname := testSurname
 	u.Surname = &surname
 
 	args := []driver.Value{sqlmock.AnyArg(), sqlmock.AnyArg(), sqlmock.AnyArg(),
@@ -284,7 +289,7 @@ func testUserCreateOneWithSurname(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB)
 
 func testUserUpdateByEmail(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	u := getUser()
-	req := "UPDATE `users` SET `name` = ? WHERE `users`.deleted_at IS NULL AND ((email = ?))"
+	req := "UPDATE `users` SET `name` = ? WHERE `users`.`deleted_at` IS NULL AND ((email = ?))"
 	m.ExpectExec(fixedFullRe(req)).
 		WithArgs(u.Name, u.Email).
 		WillReturnResult(sqlmock.NewResult(0, 1))
@@ -299,7 +304,7 @@ func testUserUpdateByEmail(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 
 func testUserUpdateFieldsByPK(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	u := getUser()
-	req := "UPDATE `users` SET `name` = ? WHERE `users`.deleted_at IS NULL AND `users`.`id` = ?"
+	req := "UPDATE `users` SET `name` = ? WHERE `users`.`deleted_at` IS NULL AND `users`.`id` = ?"
 	m.ExpectExec(fixedFullRe(req)).
 		WithArgs(u.Name, u.ID).
 		WillReturnResult(sqlmock.NewResult(0, 1))
@@ -309,7 +314,7 @@ func testUserUpdateFieldsByPK(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 
 func testUserDeleteByEmail(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	u := getUser()
-	req := "UPDATE `users` SET deleted_at=? WHERE `users`.deleted_at IS NULL AND ((email = ?))"
+	req := "UPDATE `users` SET `deleted_at`=? WHERE `users`.`deleted_at` IS NULL AND ((email = ?))"
 	m.ExpectExec(fixedFullRe(req)).
 		WithArgs(sqlmock.AnyArg(), u.Email).
 		WillReturnResult(sqlmock.NewResult(0, 1))
@@ -322,7 +327,7 @@ func testUserDeleteByEmail(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 
 func testUserDeleteByPK(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	u := getUser()
-	req := "UPDATE `users` SET deleted_at=? WHERE `users`.deleted_at IS NULL AND `users`.`id` = ?"
+	req := "UPDATE `users` SET `deleted_at`=? WHERE `users`.`deleted_at` IS NULL AND `users`.`id` = ?"
 	m.ExpectExec(fixedFullRe(req)).
 		WithArgs(sqlmock.AnyArg(), u.ID).
 		WillReturnResult(sqlmock.NewResult(0, 1))
@@ -333,7 +338,7 @@ func testUserDeleteByPK(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 func testUsersDeleteNum(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	usersNum := 2
 	users := getTestUsers(usersNum)
-	req := "UPDATE `users` SET deleted_at=? WHERE `users`.deleted_at IS NULL AND ((email IN (?,?)))"
+	req := "UPDATE `users` SET `deleted_at`=? WHERE `users`.`deleted_at` IS NULL AND ((email IN (?,?)))"
 	m.ExpectExec(fixedFullRe(req)).
 		WithArgs(sqlmock.AnyArg(), users[0].Email, users[1].Email).
 		WillReturnResult(sqlmock.NewResult(0, int64(usersNum)))
@@ -363,7 +368,7 @@ func testUsersDeleteNumUnscoped(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 func testUsersUpdateNum(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	usersNum := 2
 	users := getTestUsers(usersNum)
-	req := "UPDATE `users` SET `name` = ? WHERE `users`.deleted_at IS NULL AND ((email IN (?,?)))"
+	req := "UPDATE `users` SET `name` = ? WHERE `users`.`deleted_at` IS NULL AND ((email IN (?,?)))"
 	m.ExpectExec(fixedFullRe(req)).
 		WithArgs(sqlmock.AnyArg(), users[0].Email, users[1].Email).
 		WillReturnResult(sqlmock.NewResult(0, int64(usersNum)))
@@ -379,7 +384,7 @@ func testUsersUpdateNum(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 
 func testUsersCount(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 	expCount := 5
-	req := "SELECT count(*) FROM `users` WHERE `users`.deleted_at IS NULL AND ((name != ?))"
+	req := "SELECT count(*) FROM `users` WHERE `users`.`deleted_at` IS NULL AND ((name != ?))"
 	m.ExpectQuery(fixedFullRe(req)).WithArgs(driver.Value("")).
 		WillReturnRows(getRowWithFields([]driver.Value{expCount}))
 
@@ -389,7 +394,10 @@ func testUsersCount(t *testing.T, m sqlmock.Sqlmock, db *gorm.DB) {
 }
 
 func TestMain(m *testing.M) {
-	err := GenerateQuerySets("test/models.go", "test/autogenerated_models.go")
+	g := Generator{
+		StructsParser: &parser.Structs{},
+	}
+	err := g.Generate(context.Background(), "test/models.go", "test/autogenerated_models.go")
 	if err != nil {
 		panic(err)
 	}
@@ -398,8 +406,12 @@ func TestMain(m *testing.M) {
 }
 
 func BenchmarkHello(b *testing.B) {
+	g := Generator{
+		StructsParser: &parser.Structs{},
+	}
+
 	for i := 0; i < b.N; i++ {
-		err := GenerateQuerySets("test/models.go", "test/autogenerated_models.go")
+		err := g.Generate(context.Background(), "test/models.go", "test/autogenerated_models.go")
 		if err != nil {
 			b.Fatalf("can't generate querysets: %s", err)
 		}
diff --git a/queryset/template.go b/internal/queryset/generator/template.go
similarity index 99%
rename from queryset/template.go
rename to internal/queryset/generator/template.go
index d0ed0af..c6d2633 100644
--- a/queryset/template.go
+++ b/internal/queryset/generator/template.go
@@ -1,4 +1,4 @@
-package queryset
+package generator
 
 import (
 	"text/template"
diff --git a/queryset/test/autogenerated_models.go b/internal/queryset/generator/test/autogenerated_models.go
similarity index 99%
rename from queryset/test/autogenerated_models.go
rename to internal/queryset/generator/test/autogenerated_models.go
index 48fe53a..315655b 100644
--- a/queryset/test/autogenerated_models.go
+++ b/internal/queryset/generator/test/autogenerated_models.go
@@ -7,7 +7,7 @@ import (
 	"time"
 
 	"github.com/jinzhu/gorm"
-	"github.com/jirfag/go-queryset/queryset/tmp"
+	"github.com/jirfag/go-queryset/internal/queryset/generator/tmp"
 )
 
 // ===== BEGIN of all query sets
diff --git a/queryset/test/models.go b/internal/queryset/generator/test/models.go
similarity index 86%
rename from queryset/test/models.go
rename to internal/queryset/generator/test/models.go
index 851e690..7ec12fe 100644
--- a/queryset/test/models.go
+++ b/internal/queryset/generator/test/models.go
@@ -2,10 +2,10 @@ package test
 
 import (
 	"github.com/jinzhu/gorm"
-	"github.com/jirfag/go-queryset/queryset/tmp"
+	"github.com/jirfag/go-queryset/internal/queryset/generator/tmp"
 )
 
-//go:generate go run ../../cmd/goqueryset/goqueryset.go -in models.go
+//go:generate go run ../../../../cmd/goqueryset/goqueryset.go -in models.go
 
 // User is a usual user
 // gen:qs
diff --git a/queryset/test/pkgimport/autogenerated_models.go b/internal/queryset/generator/test/pkgimport/autogenerated_models.go
similarity index 99%
rename from queryset/test/pkgimport/autogenerated_models.go
rename to internal/queryset/generator/test/pkgimport/autogenerated_models.go
index 0545eff..7df060a 100644
--- a/queryset/test/pkgimport/autogenerated_models.go
+++ b/internal/queryset/generator/test/pkgimport/autogenerated_models.go
@@ -6,7 +6,7 @@ import (
 	"fmt"
 
 	"github.com/jinzhu/gorm"
-	forex "github.com/jirfag/go-queryset/queryset/test/pkgimport/forex/v1"
+	forex "github.com/jirfag/go-queryset/internal/queryset/generator/test/pkgimport/forex/v1"
 )
 
 // ===== BEGIN of all query sets
diff --git a/queryset/test/pkgimport/forex/v1/types.go b/internal/queryset/generator/test/pkgimport/forex/v1/types.go
similarity index 100%
rename from queryset/test/pkgimport/forex/v1/types.go
rename to internal/queryset/generator/test/pkgimport/forex/v1/types.go
diff --git a/queryset/test/pkgimport/models.go b/internal/queryset/generator/test/pkgimport/models.go
similarity index 55%
rename from queryset/test/pkgimport/models.go
rename to internal/queryset/generator/test/pkgimport/models.go
index f296675..3cb8171 100644
--- a/queryset/test/pkgimport/models.go
+++ b/internal/queryset/generator/test/pkgimport/models.go
@@ -3,8 +3,8 @@ package models
 //go:generate goqueryset -in models.go
 
 import (
-	forex "github.com/jirfag/go-queryset/queryset/test/pkgimport/forex/v1"
-	forexAlias "github.com/jirfag/go-queryset/queryset/test/pkgimport/forex/v1"
+	forex "github.com/jirfag/go-queryset/internal/queryset/generator/test/pkgimport/forex/v1"
+	forexAlias "github.com/jirfag/go-queryset/internal/queryset/generator/test/pkgimport/forex/v1"
 )
 
 // Example is a test struct
diff --git a/queryset/tmp/tmp.go b/internal/queryset/generator/tmp/tmp.go
similarity index 100%
rename from queryset/tmp/tmp.go
rename to internal/queryset/generator/tmp/tmp.go
diff --git a/queryset/methods/base.go b/internal/queryset/methods/base.go
similarity index 100%
rename from queryset/methods/base.go
rename to internal/queryset/methods/base.go
diff --git a/queryset/methods/context.go b/internal/queryset/methods/context.go
similarity index 92%
rename from queryset/methods/context.go
rename to internal/queryset/methods/context.go
index 62337df..93582f1 100644
--- a/queryset/methods/context.go
+++ b/internal/queryset/methods/context.go
@@ -1,8 +1,8 @@
 package methods
 
 import (
-	"github.com/jirfag/go-queryset/parser"
-	"github.com/jirfag/go-queryset/queryset/field"
+	"github.com/jirfag/go-queryset/internal/parser"
+	"github.com/jirfag/go-queryset/internal/queryset/field"
 )
 
 type QsStructContext struct {
diff --git a/queryset/methods/field_utils.go b/internal/queryset/methods/field_utils.go
similarity index 100%
rename from queryset/methods/field_utils.go
rename to internal/queryset/methods/field_utils.go
diff --git a/queryset/methods/field_utils_test.go b/internal/queryset/methods/field_utils_test.go
similarity index 100%
rename from queryset/methods/field_utils_test.go
rename to internal/queryset/methods/field_utils_test.go
diff --git a/queryset/methods/fields.go b/internal/queryset/methods/fields.go
similarity index 100%
rename from queryset/methods/fields.go
rename to internal/queryset/methods/fields.go
diff --git a/queryset/methods/gorm.go b/internal/queryset/methods/gorm.go
similarity index 100%
rename from queryset/methods/gorm.go
rename to internal/queryset/methods/gorm.go
diff --git a/queryset/methods/queryset.go b/internal/queryset/methods/queryset.go
similarity index 94%
rename from queryset/methods/queryset.go
rename to internal/queryset/methods/queryset.go
index 724a4c1..76d14c0 100644
--- a/queryset/methods/queryset.go
+++ b/internal/queryset/methods/queryset.go
@@ -272,27 +272,27 @@ func NewDeleteMethod(qsTypeName, structTypeName string) DeleteMethod {
 
 // DeleteNumMethod creates DeleteNum method
 type DeleteNumMethod struct {
-        namedMethod
-        baseQuerySetMethod
+	namedMethod
+	baseQuerySetMethod
 
-        noArgsMethod
-        constBodyMethod
-        constRetMethod
+	noArgsMethod
+	constBodyMethod
+	constRetMethod
 }
 
 // NewDeleteNumMethod delete row count
 func NewDeleteNumMethod(qsTypeName, structTypeName string) DeleteNumMethod {
-        return DeleteNumMethod{
-                namedMethod:        newNamedMethod("DeleteNum"),
-                baseQuerySetMethod: newBaseQuerySetMethod(qsTypeName),
-                constRetMethod:     newConstRetMethod("(int64, error)"),
-                constBodyMethod: newConstBodyMethod(
-                        strings.Join([]string{
-                                "db := qs.db.Delete(" + structTypeName + "{}" + ")",
-                                "return db.RowsAffected, db.Error",
-                        }, "\n"),
-                ),
-        }
+	return DeleteNumMethod{
+		namedMethod:        newNamedMethod("DeleteNum"),
+		baseQuerySetMethod: newBaseQuerySetMethod(qsTypeName),
+		constRetMethod:     newConstRetMethod("(int64, error)"),
+		constBodyMethod: newConstBodyMethod(
+			strings.Join([]string{
+				"db := qs.db.Delete(" + structTypeName + "{}" + ")",
+				"return db.RowsAffected, db.Error",
+			}, "\n"),
+		),
+	}
 }
 
 // DeleteNumUnscopedMethod creates DeleteNumUnscoped method for performing hard deletes
diff --git a/queryset/methods/struct.go b/internal/queryset/methods/struct.go
similarity index 100%
rename from queryset/methods/struct.go
rename to internal/queryset/methods/struct.go
diff --git a/queryset/methods/updater.go b/internal/queryset/methods/updater.go
similarity index 100%
rename from queryset/methods/updater.go
rename to internal/queryset/methods/updater.go
diff --git a/queryset/bootstrap.go b/queryset/bootstrap.go
deleted file mode 100644
index b0dc254..0000000
--- a/queryset/bootstrap.go
+++ /dev/null
@@ -1,93 +0,0 @@
-package queryset
-
-import (
-	"bytes"
-	"fmt"
-	"io"
-	"log"
-	"os"
-	"path/filepath"
-
-	"github.com/jirfag/go-queryset/parser"
-	"golang.org/x/tools/go/loader"
-	"golang.org/x/tools/imports"
-)
-
-// GenerateQuerySets generates output file with querysets
-func GenerateQuerySets(inFilePath, outFilePath string) error {
-	pkgInfo, structs, err := parser.GetStructsInFile(inFilePath)
-	if err != nil {
-		return fmt.Errorf("can't parse file %s to get structs: %s", inFilePath, err)
-	}
-
-	var r io.Reader
-	r, err = GenerateQuerySetsForStructs(pkgInfo, structs)
-	if err != nil {
-		return fmt.Errorf("can't generate query sets: %s", err)
-	}
-
-	if r == nil {
-		return fmt.Errorf("no structs to generate query set in %s", inFilePath)
-	}
-
-	if err = writeQuerySetsToOutput(r, pkgInfo, outFilePath); err != nil {
-		return fmt.Errorf("can't save query sets to out file %s: %s", outFilePath, err)
-	}
-
-	var absOutPath string
-	absOutPath, err = filepath.Abs(outFilePath)
-	if err != nil {
-		absOutPath = outFilePath
-	}
-
-	log.Printf("successfully wrote querysets to %s", absOutPath)
-	return nil
-}
-
-func writeQuerySetsToOutput(r io.Reader, pkgInfo *loader.PackageInfo, outFile string) error {
-	const hdrTmpl = `%s
-	package %s
-
-import (
-	"errors"
-	"fmt"
-	"time"
-
-	"github.com/jinzhu/gorm"
-)
-`
-
-	// https://golang.org/s/generatedcode
-	const genHdr = `// Code generated by go-queryset. DO NOT EDIT.`
-
-	var buf bytes.Buffer
-	pkgName := fmt.Sprintf(hdrTmpl, genHdr, pkgInfo.Pkg.Name())
-	if _, err := buf.WriteString(pkgName); err != nil {
-		return fmt.Errorf("can't write hdr string into buf: %s", err)
-	}
-	if _, err := io.Copy(&buf, r); err != nil {
-		return fmt.Errorf("can't write to buf: %s", err)
-	}
-
-	formattedRes, err := imports.Process(outFile, buf.Bytes(), nil)
-	if err != nil {
-		return fmt.Errorf("can't format generated file: %s", err)
-	}
-
-	var outF *os.File
-	outF, err = os.OpenFile(outFile, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0640) // nolint: gas
-	if err != nil {
-		return fmt.Errorf("can't open out file: %s", err)
-	}
-	defer func() {
-		if e := outF.Close(); e != nil {
-			log.Printf("can't close file: %s", e)
-		}
-	}()
-
-	if _, err = outF.Write(formattedRes); err != nil {
-		return fmt.Errorf("can't write to out file: %s", err)
-	}
-
-	return nil
-}
diff --git a/queryset/compile b/queryset/compile
deleted file mode 100644
index 28efd77..0000000
Binary files a/queryset/compile and /dev/null differ