package selfupdate import (	"encoding/json"	"fmt"	"io"	"net/http"	"os"	"strings") // Repo is the GitHub repository release assets are published to.const Repo = "davis7dotsh/tx9" // ErrNoRelease indicates the repository has no published releases yet.// GitHub's /releases/latest returns 404 in that case, which is the// expected state until the first `v*` tag is pushed (see// .github/workflows/release.yml) — callers should surface this as a// clean, actionable message rather than a raw HTTP error.var ErrNoRelease = fmt.Errorf("no releases published yet") // Asset is one file attached to a GitHub release.type Asset struct {	Name               string `json:"name"`	BrowserDownloadURL string `json:"browser_download_url"`} // Release is the subset of the GitHub releases API response this package// needs.type Release struct {	TagName string  `json:"tag_name"`	Assets  []Asset `json:"assets"`} // FindAsset returns the asset in r named name, or false if absent.func (r *Release) FindAsset(name string) (Asset, bool) {	for _, a := range r.Assets {		if a.Name == name {			return a, true		}	}	return Asset{}, false} func (r *Release) assetNames() string {	names := make([]string, len(r.Assets))	for i, a := range r.Assets {		names[i] = a.Name	}	return strings.Join(names, ", ")} // FetchLatestRelease queries the GitHub API for Repo's latest release. It// honors the GITHUB_TOKEN environment variable (if set) as a bearer// credential on the API call only, to avoid the low unauthenticated rate// limit — it is deliberately NOT attached to asset download requests,// since browser_download_url responses are signed redirects that an extra// Authorization header can break.func FetchLatestRelease(httpClient *http.Client) (*Release, error) {	url := fmt.Sprintf("https://api.github.com/repos/%s/releases/latest", Repo)	req, err := http.NewRequest(http.MethodGet, url, nil)	if err != nil {		return nil, fmt.Errorf("selfupdate: build request: %w", err)	}	req.Header.Set("User-Agent", userAgent)	req.Header.Set("Accept", "application/vnd.github+json")	if tok := os.Getenv("GITHUB_TOKEN"); tok != "" {		req.Header.Set("Authorization", "Bearer "+tok)	} 	resp, err := httpClient.Do(req)	if err != nil {		return nil, fmt.Errorf("selfupdate: fetch latest release: %w", err)	}	defer resp.Body.Close() 	if resp.StatusCode == http.StatusNotFound {		return nil, ErrNoRelease	}	if resp.StatusCode != http.StatusOK {		body, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))		return nil, fmt.Errorf("selfupdate: GitHub API returned %s: %s", resp.Status, strings.TrimSpace(string(body)))	} 	var rel Release	if err := json.NewDecoder(resp.Body).Decode(&rel); err != nil {		return nil, fmt.Errorf("selfupdate: decode release response: %w", err)	}	if rel.TagName == "" {		return nil, fmt.Errorf("selfupdate: release response missing tag_name")	}	return &rel, nil}