feat(fileutil): add ReadFile func (#140)

fileutil/file.go

@@ -22,6 +22,8 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
+
+	"github.com/duke-git/lancet/v2/validator"
 )
 
 // IsExist checks if a file or directory exists.
@@ -624,3 +626,24 @@ func WriteBytesToFile(filepath string, content []byte) error {
 	_, err = f.Write(content)
 	return err
 }
+
+// ReadFile get file reader by a url or a local file
+// Play: todo
+func ReadFile(path string) (reader io.ReadCloser, closeFn func(), err error) {
+	switch {
+	case validator.IsUrl(path):
+		resp, err := http.Get(path)
+		if err != nil {
+			return nil, func() {}, err
+		}
+		return resp.Body, func() { resp.Body.Close() }, nil
+	case IsExist(path):
+		reader, err := os.Open(path)
+		if err != nil {
+			return nil, func() {}, err
+		}
+		return reader, func() { reader.Close() }, nil
+	default:
+		return nil, func() {}, errors.New("unknown file type")
+	}
+}

fileutil/file_example_test.go

@@ -2,6 +2,7 @@ package fileutil
 
 import (
 	"fmt"
+	"io"
 	"os"
 )
 
@@ -385,3 +386,20 @@ func ExampleWriteBytesToFile() {
 	// Output:
 	// hello
 }
+
+func ExampleReadFile() {
+	reader, fn, err := ReadFile("https://httpbin.org/robots.txt")
+	if err != nil {
+		return
+	}
+	defer fn()
+
+	dat, err := io.ReadAll(reader)
+	if err != nil {
+		return
+	}
+	fmt.Println(string(dat))
+	// Output:
+	// User-agent: *
+	// Disallow: /deny
+}

fileutil/file_test.go

@@ -1,6 +1,7 @@
 package fileutil
 
 import (
+	"io"
 	"os"
 	"testing"
 
@@ -457,3 +458,21 @@ func TestWriteBytesToFile(t *testing.T) {
 
 	os.Remove(filepath)
 }
+
+func TestReadFile(t *testing.T) {
+	reader, close, err := ReadFile("https://httpbin.org/robots.txt")
+	if err != nil {
+		t.Fail()
+	}
+	defer close()
+
+	dat, err := io.ReadAll(reader)
+	if err != nil {
+		t.Fail()
+	}
+
+	want := `User-agent: *
+Disallow: /deny
+`
+	internal.NewAssert(t, "TestReadFile").Equal(want, string(dat))
+}