chore: import upstream snapshot with attribution

pkg/checker/question_link.go

@@ -0,0 +1,131 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 checker
+
+import (
+	"github.com/apache/answer/internal/base/constant"
+	"github.com/apache/answer/pkg/obj"
+	"github.com/apache/answer/pkg/uid"
+)
+
+const (
+	QuestionLinkTypeURL = 1
+	QuestionLinkTypeID  = 2
+)
+
+type QuestionLink struct {
+	LinkType   int
+	QuestionID string
+	AnswerID   string
+}
+
+func GetQuestionLink(content string) []QuestionLink {
+	uniqueIDs := make(map[string]struct{})
+	var questionLinks []QuestionLink
+
+	// use two pointer to find the link
+	left, right := 0, 0
+	for right < len(content) {
+		// find "/questions/" or "#"
+		switch {
+		case right+11 < len(content) && content[right:right+11] == "/questions/":
+			left = right
+			right += 11
+			processURL(content, &left, &right, uniqueIDs, &questionLinks)
+		case content[right] == '#':
+			left = right + 1
+			right = left
+			processID(content, &left, &right, uniqueIDs, &questionLinks)
+		default:
+			right++
+		}
+	}
+
+	return questionLinks
+}
+
+func processURL(content string, left, right *int, uniqueIDs map[string]struct{}, questionLinks *[]QuestionLink) {
+	for *right < len(content) && (isDigit(content[*right]) || isLetter(content[*right])) {
+		*right++
+	}
+	questionID := content[*left+len("/questions/") : *right]
+
+	answerID := ""
+	if *right < len(content) && content[*right] == '/' {
+		*left = *right + 1
+		*right = *left
+		for *right < len(content) && (isDigit(content[*right]) || isLetter(content[*right])) {
+			*right++
+		}
+		answerID = content[*left:*right]
+	}
+
+	addUniqueID(questionID, answerID, QuestionLinkTypeURL, uniqueIDs, questionLinks)
+}
+
+func processID(content string, left, right *int, uniqueIDs map[string]struct{}, questionLinks *[]QuestionLink) {
+	for *right < len(content) && (isDigit(content[*right]) || isLetter(content[*right])) {
+		*right++
+	}
+	id := content[*left:*right]
+	addUniqueID(id, "", QuestionLinkTypeID, uniqueIDs, questionLinks)
+}
+
+func isDigit(c byte) bool {
+	return c >= '0' && c <= '9'
+}
+
+func isLetter(c byte) bool {
+	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
+}
+
+func addUniqueID(questionID, answerID string, linkType int, uniqueIDs map[string]struct{}, questionLinks *[]QuestionLink) {
+	isAdd := false
+	if answerID != "" {
+		objectType, err := obj.GetObjectTypeStrByObjectID(uid.DeShortID(answerID))
+		if err != nil {
+			answerID = ""
+		} else if objectType == constant.AnswerObjectType {
+			if _, ok := uniqueIDs[answerID]; !ok {
+				uniqueIDs[answerID] = struct{}{}
+				isAdd = true
+			}
+		}
+	}
+
+	if objectType, err := obj.GetObjectTypeStrByObjectID(uid.DeShortID(questionID)); err == nil {
+		if _, ok := uniqueIDs[questionID]; !ok {
+			uniqueIDs[questionID] = struct{}{}
+			isAdd = true
+			if objectType == constant.AnswerObjectType {
+				answerID = questionID
+				questionID = ""
+			}
+		}
+	}
+
+	if isAdd {
+		*questionLinks = append(*questionLinks, QuestionLink{
+			LinkType:   linkType,
+			QuestionID: questionID,
+			AnswerID:   answerID,
+		})
+	}
+}