modules/markup: move common functions to markup.go

1 files changed, 335 insertions, 0 deletions

diff --git a/modules/markup/markup.go b/modules/markup/markup.go
new file mode 100644
index 00000000..a1c862a9
--- /dev/null
+++ b/modules/markup/markup.go
@@ -0,0 +1,335 @@
+// Copyright 2017 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package markup
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"regexp"
+	"strings"
+
+	"github.com/Unknwon/com"
+	"golang.org/x/net/html"
+
+	"github.com/gogits/gogs/modules/base"
+	"github.com/gogits/gogs/modules/setting"
+)
+
+// IsReadmeFile reports whether name looks like a README file based on its extension.
+func IsReadmeFile(name string) bool {
+	return strings.HasPrefix(strings.ToLower(name), "readme")
+}
+
+const (
+	ISSUE_NAME_STYLE_NUMERIC      = "numeric"
+	ISSUE_NAME_STYLE_ALPHANUMERIC = "alphanumeric"
+)
+
+var (
+	// MentionPattern matches string that mentions someone, e.g. @Unknwon
+	MentionPattern = regexp.MustCompile(`(\s|^|\W)@[0-9a-zA-Z-_\.]+`)
+
+	// CommitPattern matches link to certain commit with or without trailing hash,
+	// e.g. https://try.gogs.io/gogs/gogs/commit/d8a994ef243349f321568f9e36d5c3f444b99cae#diff-2
+	CommitPattern = regexp.MustCompile(`(\s|^)https?.*commit/[0-9a-zA-Z]+(#+[0-9a-zA-Z-]*)?`)
+
+	// IssueFullPattern matches link to an issue with or without trailing hash,
+	// e.g. https://try.gogs.io/gogs/gogs/issues/4#issue-685
+	IssueFullPattern = regexp.MustCompile(`(\s|^)https?.*issues/[0-9]+(#+[0-9a-zA-Z-]*)?`)
+	// IssueNumericPattern matches string that references to a numeric issue, e.g. #1287
+	IssueNumericPattern = regexp.MustCompile(`( |^|\()#[0-9]+\b`)
+	// IssueAlphanumericPattern matches string that references to an alphanumeric issue, e.g. ABC-1234
+	IssueAlphanumericPattern = regexp.MustCompile(`( |^|\()[A-Z]{1,10}-[1-9][0-9]*\b`)
+	// CrossReferenceIssueNumericPattern matches string that references a numeric issue in a difference repository
+	// e.g. gogits/gogs#12345
+	CrossReferenceIssueNumericPattern = regexp.MustCompile(`( |^)[0-9a-zA-Z-_\.]+/[0-9a-zA-Z-_\.]+#[0-9]+\b`)
+
+	// Sha1CurrentPattern matches string that represents a commit SHA, e.g. d8a994ef243349f321568f9e36d5c3f444b99cae
+	// FIXME: this pattern matches pure numbers as well, right now we do a hack to check in RenderSha1CurrentPattern
+	// by converting string to a number.
+	Sha1CurrentPattern = regexp.MustCompile(`\b[0-9a-f]{40}\b`)
+)
+
+// FindAllMentions matches mention patterns in given content
+// and returns a list of found user names without @ prefix.
+func FindAllMentions(content string) []string {
+	mentions := MentionPattern.FindAllString(content, -1)
+	for i := range mentions {
+		mentions[i] = mentions[i][strings.Index(mentions[i], "@")+1:] // Strip @ character
+	}
+	return mentions
+}
+
+// cutoutVerbosePrefix cutouts URL prefix including sub-path to
+// return a clean unified string of request URL path.
+func cutoutVerbosePrefix(prefix string) string {
+	if len(prefix) == 0 || prefix[0] != '/' {
+		return prefix
+	}
+	count := 0
+	for i := 0; i < len(prefix); i++ {
+		if prefix[i] == '/' {
+			count++
+		}
+		if count >= 3+setting.AppSubUrlDepth {
+			return prefix[:i]
+		}
+	}
+	return prefix
+}
+
+// RenderIssueIndexPattern renders issue indexes to corresponding links.
+func RenderIssueIndexPattern(rawBytes []byte, urlPrefix string, metas map[string]string) []byte {
+	urlPrefix = cutoutVerbosePrefix(urlPrefix)
+
+	pattern := IssueNumericPattern
+	if metas["style"] == ISSUE_NAME_STYLE_ALPHANUMERIC {
+		pattern = IssueAlphanumericPattern
+	}
+
+	ms := pattern.FindAll(rawBytes, -1)
+	for _, m := range ms {
+		if m[0] == ' ' || m[0] == '(' {
+			m = m[1:] // ignore leading space or opening parentheses
+		}
+		var link string
+		if metas == nil {
+			link = fmt.Sprintf(`<a href="%s/issues/%s">%s</a>`, urlPrefix, m[1:], m)
+		} else {
+			// Support for external issue tracker
+			if metas["style"] == ISSUE_NAME_STYLE_ALPHANUMERIC {
+				metas["index"] = string(m)
+			} else {
+				metas["index"] = string(m[1:])
+			}
+			link = fmt.Sprintf(`<a href="%s">%s</a>`, com.Expand(metas["format"], metas), m)
+		}
+		rawBytes = bytes.Replace(rawBytes, m, []byte(link), 1)
+	}
+	return rawBytes
+}
+
+// Note: this section is for purpose of increase performance and
+// reduce memory allocation at runtime since they are constant literals.
+var pound = []byte("#")
+
+// RenderCrossReferenceIssueIndexPattern renders issue indexes from other repositories to corresponding links.
+func RenderCrossReferenceIssueIndexPattern(rawBytes []byte, urlPrefix string, metas map[string]string) []byte {
+	ms := CrossReferenceIssueNumericPattern.FindAll(rawBytes, -1)
+	for _, m := range ms {
+		if m[0] == ' ' || m[0] == '(' {
+			m = m[1:] // ignore leading space or opening parentheses
+		}
+
+		delimIdx := bytes.Index(m, pound)
+		repo := string(m[:delimIdx])
+		index := string(m[delimIdx+1:])
+
+		link := fmt.Sprintf(`<a href="%s%s/issues/%s">%s</a>`, setting.AppUrl, repo, index, m)
+		rawBytes = bytes.Replace(rawBytes, m, []byte(link), 1)
+	}
+	return rawBytes
+}
+
+// RenderSha1CurrentPattern renders SHA1 strings to corresponding links that assumes in the same repository.
+func RenderSha1CurrentPattern(rawBytes []byte, urlPrefix string) []byte {
+	return []byte(Sha1CurrentPattern.ReplaceAllStringFunc(string(rawBytes[:]), func(m string) string {
+		if com.StrTo(m).MustInt() > 0 {
+			return m
+		}
+		return fmt.Sprintf(`<a href="%s/commit/%s"><code>%s</code></a>`, urlPrefix, m, base.ShortSha(string(m)))
+	}))
+}
+
+// RenderSpecialLink renders mentions, indexes and SHA1 strings to corresponding links.
+func RenderSpecialLink(rawBytes []byte, urlPrefix string, metas map[string]string) []byte {
+	ms := MentionPattern.FindAll(rawBytes, -1)
+	for _, m := range ms {
+		m = m[bytes.Index(m, []byte("@")):]
+		rawBytes = bytes.Replace(rawBytes, m,
+			[]byte(fmt.Sprintf(`<a href="%s/%s">%s</a>`, setting.AppSubUrl, m[1:], m)), -1)
+	}
+
+	rawBytes = RenderIssueIndexPattern(rawBytes, urlPrefix, metas)
+	rawBytes = RenderCrossReferenceIssueIndexPattern(rawBytes, urlPrefix, metas)
+	rawBytes = RenderSha1CurrentPattern(rawBytes, urlPrefix)
+	return rawBytes
+}
+
+var (
+	leftAngleBracket  = []byte("</")
+	rightAngleBracket = []byte(">")
+)
+
+var noEndTags = []string{"input", "br", "hr", "img"}
+
+// wrapImgWithLink warps link to standalone <img> tags.
+func wrapImgWithLink(urlPrefix string, buf *bytes.Buffer, token html.Token) {
+	// Extract "src" and "alt" attributes
+	var src, alt string
+	for i := range token.Attr {
+		switch token.Attr[i].Key {
+		case "src":
+			src = token.Attr[i].Val
+		case "alt":
+			alt = token.Attr[i].Val
+		}
+	}
+
+	// Skip in case the "src" is empty
+	if len(src) == 0 {
+		buf.WriteString(token.String())
+		return
+	}
+
+	// Prepend repository base URL for internal links
+	needPrepend := !isLink([]byte(src))
+	if needPrepend {
+		urlPrefix = strings.Replace(urlPrefix, "/src/", "/raw/", 1)
+		if src[0] != '/' {
+			urlPrefix += "/"
+		}
+	}
+
+	buf.WriteString(`<a href="`)
+	if needPrepend {
+		buf.WriteString(urlPrefix)
+		buf.WriteString(src)
+	} else {
+		buf.WriteString(src)
+	}
+	buf.WriteString(`">`)
+
+	if needPrepend {
+		src = strings.Replace(urlPrefix+string(src), " ", "%20", -1)
+		buf.WriteString(`<img src="`)
+		buf.WriteString(src)
+		buf.WriteString(`"`)
+
+		if len(alt) > 0 {
+			buf.WriteString(` alt="`)
+			buf.WriteString(alt)
+			buf.WriteString(`"`)
+		}
+
+		buf.WriteString(`>`)
+
+	} else {
+		buf.WriteString(token.String())
+	}
+
+	buf.WriteString(`</a>`)
+}
+
+// postProcessHTML treats different types of HTML differently,
+// and only renders special links for plain text blocks.
+func postProcessHTML(rawHTML []byte, urlPrefix string, metas map[string]string) []byte {
+	startTags := make([]string, 0, 5)
+	buf := bytes.NewBuffer(nil)
+	tokenizer := html.NewTokenizer(bytes.NewReader(rawHTML))
+
+OUTER_LOOP:
+	for html.ErrorToken != tokenizer.Next() {
+		token := tokenizer.Token()
+		switch token.Type {
+		case html.TextToken:
+			buf.Write(RenderSpecialLink([]byte(token.String()), urlPrefix, metas))
+
+		case html.StartTagToken:
+			tagName := token.Data
+
+			if tagName == "img" {
+				wrapImgWithLink(urlPrefix, buf, token)
+				continue OUTER_LOOP
+			}
+
+			buf.WriteString(token.String())
+			// If this is an excluded tag, we skip processing all output until a close tag is encountered.
+			if strings.EqualFold("a", tagName) || strings.EqualFold("code", tagName) || strings.EqualFold("pre", tagName) {
+				stackNum := 1
+				for html.ErrorToken != tokenizer.Next() {
+					token = tokenizer.Token()
+
+					// Copy the token to the output verbatim
+					buf.WriteString(token.String())
+
+					// Stack number doesn't increate for tags without end tags.
+					if token.Type == html.StartTagToken && !com.IsSliceContainsStr(noEndTags, token.Data) {
+						stackNum++
+					}
+
+					// If this is the close tag to the outer-most, we are done
+					if token.Type == html.EndTagToken {
+						stackNum--
+						if stackNum <= 0 && strings.EqualFold(tagName, token.Data) {
+							break
+						}
+					}
+				}
+				continue OUTER_LOOP
+			}
+
+			if !com.IsSliceContainsStr(noEndTags, tagName) {
+				startTags = append(startTags, tagName)
+			}
+
+		case html.EndTagToken:
+			if len(startTags) == 0 {
+				buf.WriteString(token.String())
+				break
+			}
+
+			buf.Write(leftAngleBracket)
+			buf.WriteString(startTags[len(startTags)-1])
+			buf.Write(rightAngleBracket)
+			startTags = startTags[:len(startTags)-1]
+		default:
+			buf.WriteString(token.String())
+		}
+	}
+
+	if io.EOF == tokenizer.Err() {
+		return buf.Bytes()
+	}
+
+	// If we are not at the end of the input, then some other parsing error has occurred,
+	// so return the input verbatim.
+	return rawHTML
+}
+
+type Type string
+
+const (
+	UNRECOGNIZED Type = "unrecognized"
+	MARKDOWN     Type = "markdown"
+	ORG_MODE     Type = "orgmode"
+)
+
+// Render takes a string or []byte and renders to HTML in given type of syntax with special links.
+func Render(typ Type, input interface{}, urlPrefix string, metas map[string]string) []byte {
+	var rawBytes []byte
+	switch v := input.(type) {
+	case []byte:
+		rawBytes = v
+	case string:
+		rawBytes = []byte(v)
+	default:
+		panic(fmt.Sprintf("unrecognized input content type: %T", input))
+	}
+
+	urlPrefix = strings.Replace(urlPrefix, " ", "%20", -1)
+	var rawHTML []byte
+	switch typ {
+	case MARKDOWN:
+		rawHTML = RawMarkdown(rawBytes, urlPrefix)
+	case ORG_MODE:
+	default:
+		return rawBytes // Do nothing if syntax type is not recognized
+	}
+
+	rawHTML = postProcessHTML(rawHTML, urlPrefix, metas)
+	return SanitizeBytes(rawHTML)
+}