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// Copyright 2019 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 media contains Media Type (MIME type) related types and functions.
package media
import (
"encoding/json"
"fmt"
"net/http"
"strings"
)
var zero Type
const (
DefaultDelimiter = "."
)
// MediaType (also known as MIME type and content type) is a two-part identifier for
// file formats and format contents transmitted on the Internet.
// For Hugo's use case, we use the top-level type name / subtype name + suffix.
// One example would be application/svg+xml
// If suffix is not provided, the sub type will be used.
// <docsmeta>{ "name": "MediaType" }</docsmeta>
type Type struct {
// The full MIME type string, e.g. "application/rss+xml".
Type string `json:"-"`
// The top-level type name, e.g. "application".
MainType string `json:"mainType"`
// The subtype name, e.g. "rss".
SubType string `json:"subType"`
// The delimiter before the suffix, e.g. ".".
Delimiter string `json:"delimiter"`
// FirstSuffix holds the first suffix defined for this MediaType.
FirstSuffix SuffixInfo `json:"-"`
// This is the optional suffix after the "+" in the MIME type,
// e.g. "xml" in "application/rss+xml".
mimeSuffix string
// E.g. "jpg,jpeg"
// Stored as a string to make Type comparable.
// For internal use only.
SuffixesCSV string `json:"-"`
}
// SuffixInfo holds information about a Media Type's suffix.
type SuffixInfo struct {
// Suffix is the suffix without the delimiter, e.g. "xml".
Suffix string `json:"suffix"`
// FullSuffix is the suffix with the delimiter, e.g. ".xml".
FullSuffix string `json:"fullSuffix"`
}
// FromContent resolve the Type primarily using http.DetectContentType.
// If http.DetectContentType resolves to application/octet-stream, a zero Type is returned.
// If http.DetectContentType resolves to text/plain or application/xml, we try to get more specific using types and ext.
func FromContent(types Types, extensionHints []string, content []byte) Type {
t := strings.Split(http.DetectContentType(content), ";")[0]
if t == "application/octet-stream" {
return zero
}
var found bool
m, found := types.GetByType(t)
if !found {
if t == "text/xml" {
// This is how it's configured in Hugo by default.
m, found = types.GetByType("application/xml")
}
}
if !found {
return zero
}
var mm Type
for _, extension := range extensionHints {
extension = strings.TrimPrefix(extension, ".")
mm, _, found = types.GetFirstBySuffix(extension)
if found {
break
}
}
if found {
if m == mm {
return m
}
if m.IsText() && mm.IsText() {
// http.DetectContentType isn't brilliant when it comes to common text formats, so we need to do better.
// For now we say that if it's detected to be a text format and the extension/content type in header reports
// it to be a text format, then we use that.
return mm
}
// E.g. an image with a *.js extension.
return zero
}
return m
}
// FromStringAndExt creates a Type from a MIME string and a given extension.
func FromStringAndExt(t, ext string) (Type, error) {
tp, err := FromString(t)
if err != nil {
return tp, err
}
tp.SuffixesCSV = strings.TrimPrefix(ext, ".")
tp.Delimiter = DefaultDelimiter
tp.init()
return tp, nil
}
// MustFromString is like FromString but panics on error.
func MustFromString(t string) Type {
tp, err := FromString(t)
if err != nil {
panic(err)
}
return tp
}
// FromString creates a new Type given a type string on the form MainType/SubType and
// an optional suffix, e.g. "text/html" or "text/html+html".
func FromString(t string) (Type, error) {
t = strings.ToLower(t)
parts := strings.Split(t, "/")
if len(parts) != 2 {
return Type{}, fmt.Errorf("cannot parse %q as a media type", t)
}
mainType := parts[0]
subParts := strings.Split(parts[1], "+")
subType := strings.Split(subParts[0], ";")[0]
var suffix string
if len(subParts) > 1 {
suffix = subParts[1]
}
var typ string
if suffix != "" {
typ = mainType + "/" + subType + "+" + suffix
} else {
typ = mainType + "/" + subType
}
return Type{Type: typ, MainType: mainType, SubType: subType, mimeSuffix: suffix}, nil
}
// For internal use.
func (m Type) String() string {
return m.Type
}
// Suffixes returns all valid file suffixes for this type.
func (m Type) Suffixes() []string {
if m.SuffixesCSV == "" {
return nil
}
return strings.Split(m.SuffixesCSV, ",")
}
// IsText returns whether this Type is a text format.
// Note that this may currently return false negatives.
// TODO(bep) improve
// For internal use.
func (m Type) IsText() bool {
if m.MainType == "text" {
return true
}
switch m.SubType {
case "javascript", "json", "rss", "xml", "svg", "toml", "yml", "yaml":
return true
}
return false
}
func InitMediaType(m *Type) {
m.init()
}
func (m *Type) init() {
m.FirstSuffix.FullSuffix = ""
m.FirstSuffix.Suffix = ""
if suffixes := m.Suffixes(); suffixes != nil {
m.FirstSuffix.Suffix = suffixes[0]
m.FirstSuffix.FullSuffix = m.Delimiter + m.FirstSuffix.Suffix
}
}
// WithDelimiterAndSuffixes is used in tests.
func WithDelimiterAndSuffixes(t Type, delimiter, suffixesCSV string) Type {
t.Delimiter = delimiter
t.SuffixesCSV = suffixesCSV
t.init()
return t
}
func newMediaType(main, sub string, suffixes []string) Type {
t := Type{MainType: main, SubType: sub, SuffixesCSV: strings.Join(suffixes, ","), Delimiter: DefaultDelimiter}
t.init()
return t
}
func newMediaTypeWithMimeSuffix(main, sub, mimeSuffix string, suffixes []string) Type {
mt := ne
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