import

[ddkwork]

package main

import (
    "fmt"
    "go/ast"
    "go/parser"
    "go/printer"
    "go/token"
    "os"
)

func main() {
    src := `
package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}
`

    fset := token.NewFileSet()
    node, err := parser.ParseFile(fset, "", src, parser.ParseComments)
    if err != nil {
        fmt.Println(err)
        return
    }

    newImport := &ast.GenDecl{
        Tok: token.IMPORT,
        Specs: []ast.Spec{
            &ast.ImportSpec{
                Path: &ast.BasicLit{
                    Kind:  token.STRING,
                    Value: `"time"`,
                },
            },
        },
    }

    node.Decls = append([]ast.Decl{newImport}, node.Decls...)

    printer.Fprint(os.Stdout, fset, node)
}