hugo/resource/postcss/postcss.go
2018-07-18 10:00:50 +02:00

185 lines
4.6 KiB
Go

// 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 postcss
import (
"fmt"
"io"
"path/filepath"
"github.com/gohugoio/hugo/hugofs"
"github.com/mitchellh/mapstructure"
// "io/ioutil"
"os"
"os/exec"
"github.com/gohugoio/hugo/common/errors"
"github.com/gohugoio/hugo/resource"
)
// Some of the options from https://github.com/postcss/postcss-cli
type Options struct {
// Set a custom path to look for a config file.
Config string
NoMap bool `mapstructure:"no-map"` // Disable the default inline sourcemaps
// Options for when not using a config file
Use string // List of postcss plugins to use
Parser string // Custom postcss parser
Stringifier string // Custom postcss stringifier
Syntax string // Custom postcss syntax
}
func DecodeOptions(m map[string]interface{}) (opts Options, err error) {
if m == nil {
return
}
err = mapstructure.WeakDecode(m, &opts)
return
}
func (opts Options) toArgs() []string {
var args []string
if opts.NoMap {
args = append(args, "--no-map")
}
if opts.Use != "" {
args = append(args, "--use", opts.Use)
}
if opts.Parser != "" {
args = append(args, "--parser", opts.Parser)
}
if opts.Stringifier != "" {
args = append(args, "--stringifier", opts.Stringifier)
}
if opts.Syntax != "" {
args = append(args, "--syntax", opts.Syntax)
}
return args
}
// Client is the client used to do PostCSS transformations.
type Client struct {
rs *resource.Spec
}
// New creates a new Client with the given specification.
func New(rs *resource.Spec) *Client {
return &Client{rs: rs}
}
type postcssTransformation struct {
options Options
rs *resource.Spec
}
func (t *postcssTransformation) Key() resource.ResourceTransformationKey {
return resource.NewResourceTransformationKey("postcss", t.options)
}
// Transform shells out to postcss-cli to do the heavy lifting.
// For this to work, you need some additional tools. To install them globally:
// npm install -g postcss-cli
// npm install -g autoprefixer
func (t *postcssTransformation) Transform(ctx *resource.ResourceTransformationCtx) error {
const localPostCSSPath = "node_modules/postcss-cli/bin/"
const binaryName = "postcss"
// Try first in the project's node_modules.
csiBinPath := filepath.Join(t.rs.WorkingDir, localPostCSSPath, binaryName)
binary := csiBinPath
if _, err := exec.LookPath(binary); err != nil {
// Try PATH
binary = binaryName
if _, err := exec.LookPath(binary); err != nil {
// This may be on a CI server etc. Will fall back to pre-built assets.
return errors.FeatureNotAvailableErr
}
}
var configFile string
logger := t.rs.Logger
if t.options.Config != "" {
configFile = t.options.Config
} else {
configFile = "postcss.config.js"
}
configFile = filepath.Clean(configFile)
// We need an abolute filename to the config file.
if !filepath.IsAbs(configFile) {
// We resolve this against the virtual Work filesystem, to allow
// this config file to live in one of the themes if needed.
fi, err := t.rs.BaseFs.Work.Fs.Stat(configFile)
if err != nil {
if t.options.Config != "" {
// Only fail if the user specificed config file is not found.
return fmt.Errorf("postcss config %q not found: %s", configFile, err)
}
configFile = ""
} else {
configFile = fi.(hugofs.RealFilenameInfo).RealFilename()
}
}
var cmdArgs []string
if configFile != "" {
logger.INFO.Println("postcss: use config file", configFile)
cmdArgs = []string{"--config", configFile}
}
if optArgs := t.options.toArgs(); len(optArgs) > 0 {
cmdArgs = append(cmdArgs, optArgs...)
}
cmd := exec.Command(binary, cmdArgs...)
cmd.Stdout = ctx.To
cmd.Stderr = os.Stderr
stdin, err := cmd.StdinPipe()
if err != nil {
return err
}
go func() {
defer stdin.Close()
io.Copy(stdin, ctx.From)
}()
err = cmd.Run()
if err != nil {
return err
}
return nil
}
// Process transforms the given Resource with the PostCSS processor.
func (c *Client) Process(res resource.Resource, options Options) (resource.Resource, error) {
return c.rs.Transform(
res,
&postcssTransformation{rs: c.rs, options: options},
)
}