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// Copyright 2018 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package resource
import (
"bytes"
"path"
"strconv"
"strings"
"github.com/gohugoio/hugo/common/collections"
"github.com/gohugoio/hugo/common/herrors"
"github.com/gohugoio/hugo/common/hugio"
"github.com/gohugoio/hugo/helpers"
"github.com/mitchellh/hashstructure"
"github.com/spf13/afero"
"fmt"
"io"
"sync"
"github.com/gohugoio/hugo/media"
bp "github.com/gohugoio/hugo/bufferpool"
)
var (
_ ContentResource = (*transformedResource)(nil)
_ ReadSeekCloserResource = (*transformedResource)(nil)
_ collections.Slicer = (*transformedResource)(nil)
)
func (s *Spec) Transform(r Resource, t ResourceTransformation) (Resource, error) {
return &transformedResource{
Resource: r,
transformation: t,
transformedResourceMetadata: transformedResourceMetadata{MetaData: make(map[string]interface{})},
cache: s.ResourceCache}, nil
}
type ResourceTransformationCtx struct {
// The content to transform.
From io.Reader
// The target of content transformation.
// The current implementation requires that r is written to w
// even if no transformation is performed.
To io.Writer
// This is the relative path to the original source. Unix styled slashes.
SourcePath string
// This is the relative target path to the resource. Unix styled slashes.
InPath string
// The relative target path to the transformed resource. Unix styled slashes.
OutPath string
// The input media type
InMediaType media.Type
// The media type of the transformed resource.
OutMediaType media.Type
// Data data can be set on the transformed Resource. Not that this need
// to be simple types, as it needs to be serialized to JSON and back.
Data map[string]interface{}
// This is used to publis additional artifacts, e.g. source maps.
// We may improve this.
OpenResourcePublisher func(relTargetPath string) (io.WriteCloser, error)
}
// AddOutPathIdentifier transforming InPath to OutPath adding an identifier,
// eg '.min' before any extension.
func (ctx *ResourceTransformationCtx) AddOutPathIdentifier(identifier string) {
ctx.OutPath = ctx.addPathIdentifier(ctx.InPath, identifier)
}
func (ctx *ResourceTransformationCtx) addPathIdentifier(inPath, identifier string) string {
dir, file := path.Split(inPath)
base, ext := helpers.PathAndExt(file)
return path.Join(dir, (base + identifier + ext))
}
// ReplaceOutPathExtension transforming InPath to OutPath replacing the file
// extension, e.g. ".scss"
func (ctx *ResourceTransformationCtx) ReplaceOutPathExtension(newExt string) {
dir, file := path.Split(ctx.InPath)
base, _ := helpers.PathAndExt(file)
ctx.OutPath = path.Join(dir, (base + newExt))
}
// PublishSourceMap writes the content to the target folder of the main resource
// with the ".map" extension added.
func (ctx *ResourceTransformationCtx) PublishSourceMap(content string) error {
target := ctx.OutPath + ".map"
f, err := ctx.OpenResourcePublisher(target)
if err != nil {
return err
}
defer f.Close()
_, err = f.Write([]byte(content))
return err
}
// ResourceTransformationKey are provided by the different transformation implementations.
// It identifies the transformation (name) and its configuration (elements).
// We combine this in a chain with the rest of the transformations
// with the target filename and a content hash of the origin to use as cache key.
type ResourceTransformationKey struct {
name string
elements []interface{}
}
// NewResourceTransformationKey creates a new ResourceTransformationKey from the transformation
// name and elements. We will create a 64 bit FNV hash from the elements, which when combined
// with the other key elements should be unique for all practical applications.
func NewResourceTransformationKey(name string, elements ...interface{}) ResourceTransformationKey {
return ResourceTransformationKey{name: name, elements: elements}
}
// Do not change this without good reasons.
func (k ResourceTransformationKey) key() string {
if len(k.elements) == 0 {
return k.name
}
sb := bp.GetBuffer()
defer bp.PutBuffer(sb)
sb.WriteString(k.name)
for _, element := range k.elements {
hash, err := hashstructure.Hash(element, nil)
if err != nil {
panic(err)
}
sb.WriteString("_")
sb.WriteString(strconv.FormatUint(hash, 10))
}
return sb.String()
}
// ResourceTransformation is the interface that a resource transformation step
// needs to implement.
type ResourceTransformation interface {
Key() ResourceTransformationKey
Transform(ctx *ResourceTransformationCtx) error
}
// We will persist this information to disk.
type transformedResourceMetadata struct {
Target string `json:"Target"`
MediaTypeV string `json:"MediaType"`
MetaData map[string]interface{} `json:"Data"`
}
type transformedResource struct {
commonResource
cache *ResourceCache
// This is the filename inside resources/_gen/assets
sourceFilename string
linker permalinker
// The transformation to apply.
transformation ResourceTransformation
// We apply the tranformations lazily.
transformInit sync.Once
transformErr error
// The transformed values
content string
contentInit sync.Once
transformedResourceMetadata
// The source
Resource
}
func (r *transformedResource) ReadSeekCloser() (hugio.ReadSeekCloser, error) {
if err := r.initContent(); err != nil {
return nil, err
}
return hugio.NewReadSeekerNoOpCloserFromString(r.content), nil
}
func (r *transformedResource) transferTransformedValues(another *transformedResource) {
if another
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