github.com/kovansky/hugo@v0.92.3-0.20220224232819-63076e4ff19f/transform/livereloadinject/livereloadinject.go (about)

     1  // Copyright 2018 The Hugo Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package livereloadinject
    15  
    16  import (
    17  	"bytes"
    18  	"fmt"
    19  	"html"
    20  	"net/url"
    21  	"strings"
    22  
    23  	"github.com/gohugoio/hugo/helpers"
    24  	"github.com/gohugoio/hugo/transform"
    25  )
    26  
    27  type tag struct {
    28  	markup       []byte
    29  	appendScript bool
    30  }
    31  
    32  var tags = []tag{
    33  	{markup: []byte("<head>"), appendScript: true},
    34  	{markup: []byte("<HEAD>"), appendScript: true},
    35  	{markup: []byte("</body>")},
    36  	{markup: []byte("</BODY>")},
    37  }
    38  
    39  // New creates a function that can be used
    40  // to inject a script tag for the livereload JavaScript in a HTML document.
    41  func New(baseURL url.URL) transform.Transformer {
    42  	return func(ft transform.FromTo) error {
    43  		b := ft.From().Bytes()
    44  		idx := -1
    45  		var match tag
    46  		// We used to insert the livereload script right before the closing body.
    47  		// This does not work when combined with tools such as Turbolinks.
    48  		// So we try to inject the script as early as possible.
    49  		for _, t := range tags {
    50  			idx = bytes.Index(b, t.markup)
    51  			if idx != -1 {
    52  				match = t
    53  				break
    54  			}
    55  		}
    56  
    57  		path := strings.TrimSuffix(baseURL.Path, "/")
    58  
    59  		src := path + "/livereload.js?mindelay=10&v=2"
    60  		src += "&port=" + baseURL.Port()
    61  		src += "&path=" + strings.TrimPrefix(path+"/livereload", "/")
    62  
    63  		c := make([]byte, len(b))
    64  		copy(c, b)
    65  
    66  		if idx == -1 {
    67  			_, err := ft.To().Write(c)
    68  			return err
    69  		}
    70  
    71  		script := []byte(fmt.Sprintf(`<script src="%s" data-no-instant defer></script>`, html.EscapeString(src)))
    72  
    73  		i := idx
    74  		if match.appendScript {
    75  			i += len(match.markup)
    76  		}
    77  
    78  		c = append(c[:i], append(script, c[i:]...)...)
    79  
    80  		if _, err := ft.To().Write(c); err != nil {
    81  			helpers.DistinctWarnLog.Println("Failed to inject LiveReload script:", err)
    82  		}
    83  		return nil
    84  	}
    85  }