1// Wrapper around x/tools/imports that only removes imports, never adds new ones.
  2
  3package imports
  4
  5import (
  6	"bytes"
  7	"go/ast"
  8	"go/parser"
  9	"go/printer"
 10	"go/token"
 11	"strings"
 12
 13	"github.com/99designs/gqlgen/internal/code"
 14
 15	"golang.org/x/tools/go/ast/astutil"
 16	"golang.org/x/tools/imports"
 17)
 18
 19type visitFn func(node ast.Node)
 20
 21func (fn visitFn) Visit(node ast.Node) ast.Visitor {
 22	fn(node)
 23	return fn
 24}
 25
 26// Prune removes any unused imports
 27func Prune(filename string, src []byte) ([]byte, error) {
 28	fset := token.NewFileSet()
 29
 30	file, err := parser.ParseFile(fset, filename, src, parser.ParseComments|parser.AllErrors)
 31	if err != nil {
 32		return nil, err
 33	}
 34
 35	unused, err := getUnusedImports(file, filename)
 36	if err != nil {
 37		return nil, err
 38	}
 39	for ipath, name := range unused {
 40		astutil.DeleteNamedImport(fset, file, name, ipath)
 41	}
 42	printConfig := &printer.Config{Mode: printer.TabIndent, Tabwidth: 8}
 43
 44	var buf bytes.Buffer
 45	if err := printConfig.Fprint(&buf, fset, file); err != nil {
 46		return nil, err
 47	}
 48
 49	return imports.Process(filename, buf.Bytes(), &imports.Options{FormatOnly: true, Comments: true, TabIndent: true, TabWidth: 8})
 50}
 51
 52func getUnusedImports(file ast.Node, filename string) (map[string]string, error) {
 53	imported := map[string]*ast.ImportSpec{}
 54	used := map[string]bool{}
 55
 56	ast.Walk(visitFn(func(node ast.Node) {
 57		if node == nil {
 58			return
 59		}
 60		switch v := node.(type) {
 61		case *ast.ImportSpec:
 62			if v.Name != nil {
 63				imported[v.Name.Name] = v
 64				break
 65			}
 66			ipath := strings.Trim(v.Path.Value, `"`)
 67			if ipath == "C" {
 68				break
 69			}
 70
 71			local := code.NameForPackage(ipath)
 72
 73			imported[local] = v
 74		case *ast.SelectorExpr:
 75			xident, ok := v.X.(*ast.Ident)
 76			if !ok {
 77				break
 78			}
 79			if xident.Obj != nil {
 80				// if the parser can resolve it, it's not a package ref
 81				break
 82			}
 83			used[xident.Name] = true
 84		}
 85	}), file)
 86
 87	for pkg := range used {
 88		delete(imported, pkg)
 89	}
 90
 91	unusedImport := map[string]string{}
 92	for pkg, is := range imported {
 93		if !used[pkg] && pkg != "_" && pkg != "." {
 94			name := ""
 95			if is.Name != nil {
 96				name = is.Name.Name
 97			}
 98			unusedImport[strings.Trim(is.Path.Value, `"`)] = name
 99		}
100	}
101
102	return unusedImport, nil
103}