github api: release, tag, commit

internal/github/tag.go

@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2025 The GoPlus Authors (goplus.org). 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 github
+
+import (
+	"encoding/json"
+	"errors"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+var (
+	ErrBreak    = errors.New("break")
+	ErrNotFound = errors.New("not found")
+)
+
+// Commit represents a commit in a GitHub repository.
+type Commit struct {
+	SHA string `json:"sha"`
+	URL string `json:"url"`
+}
+
+// Tag represents a GitHub tag.
+type Tag struct {
+	Name       string `json:"name"`
+	ZipballURL string `json:"zipball_url"`
+	TarballURL string `json:"tarball_url"`
+	Commit     Commit `json:"commit"`
+	NodeID     string `json:"node_id"`
+}
+
+// tagsURL constructs the URL for fetching tags from a GitHub repository.
+func tagsURL(pkgPath string) string {
+	return "https://api.github.com/repos/" + pkgPath + "/tags"
+}
+
+// GetTag retrieves a specific tag from a GitHub repository.
+func GetTag(pkgPath, ver string) (tag *Tag, err error) {
+	err = ErrNotFound
+	EnumTags(pkgPath, 0, func(tags []*Tag, page, total int) error {
+		for _, t := range tags {
+			if t.Name == ver {
+				tag = t
+				err = nil
+				return ErrBreak
+			}
+		}
+		return nil
+	})
+	return
+}
+
+// EnumTags enumerates the tags of a GitHub repository.
+func EnumTags(pkgPath string, page int, pager func(tags []*Tag, page, total int) error) (err error) {
+	total := 0
+	ubase := tagsURL(pkgPath)
+
+loop:
+	u := ubase
+	if page > 0 {
+		vals := url.Values{"page": []string{strconv.Itoa(page + 1)}}
+		u += "?" + vals.Encode()
+	}
+	resp, err := http.Get(u)
+	if err != nil {
+		return
+	}
+	defer resp.Body.Close()
+
+	var tags []*Tag
+	err = json.NewDecoder(resp.Body).Decode(&tags)
+	if err != nil {
+		return
+	}
+
+	// Link: <https://api.github.com/repositories/47859258/tags?page=2>; rel="next",
+	//       <https://api.github.com/repositories/47859258/tags?page=5>; rel="last"
+	if total == 0 {
+		const relLast = `rel="last"`
+		total = page + 1
+		link := resp.Header.Get("Link")
+		for _, part := range strings.Split(link, ",") {
+			if strings.HasSuffix(part, relLast) {
+				left := strings.TrimSpace(part[:len(part)-len(relLast)])
+				lastUrl := strings.TrimSuffix(strings.TrimPrefix(left, "<"), ">;")
+				if pos := strings.LastIndexByte(lastUrl, '?'); pos >= 0 {
+					if vals, e := url.ParseQuery(lastUrl[pos+1:]); e == nil {
+						if n, e := strconv.Atoi(vals.Get("page")); e == nil {
+							total = n
+						}
+					}
+				}
+				break
+			}
+		}
+	}
+	err = pager(tags, page, total)
+	if err != nil {
+		if err == ErrBreak {
+			err = nil
+		}
+		return
+	}
+	page++
+	if page < total {
+		goto loop
+	}
+	return
+}