Implement mcdoc v0.1.0: public documentation server

Single-binary Go server that fetches markdown from Gitea (mc org),
renders to HTML with goldmark (GFM, chroma syntax highlighting,
heading anchors), and serves a navigable read-only documentation site.

Features:
- Boot fetch with retry, webhook refresh, 15-minute poll fallback
- In-memory cache with atomic per-repo swap
- chi router with htmx partial responses for SPA-like navigation
- HMAC-SHA256 webhook validation
- Responsive CSS, TOC generation, priority doc ordering
- $PORT env var support for MCP agent port assignment

33 tests across config, cache, render, and server packages.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-03-27 13:04:15 -07:00
parent 0578dbcb02
commit 28afaa2c56
31 changed files with 2870 additions and 1 deletions

422
internal/server/server.go Normal file
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package server
import (
"context"
"crypto/hmac"
"crypto/sha256"
"encoding/hex"
"fmt"
"html/template"
"io"
"io/fs"
"log/slog"
"net/http"
"strings"
"time"
"github.com/go-chi/chi/v5"
"git.wntrmute.dev/mc/mcdoc/internal/cache"
"git.wntrmute.dev/mc/mcdoc/internal/render"
"git.wntrmute.dev/mc/mcdoc/web"
)
// Server is the mcdoc HTTP server.
type Server struct {
cache *cache.Cache
pages map[string]*template.Template
loadingTmpl *template.Template
webhookSecret string
onWebhook func(repo string)
log *slog.Logger
}
// Config holds server configuration.
type Config struct {
Cache *cache.Cache
WebhookSecret string
OnWebhook func(repo string)
Log *slog.Logger
}
// New creates a server with its routes.
func New(cfg Config) (*Server, error) {
tmplFS, err := fs.Sub(web.Content, "templates")
if err != nil {
return nil, fmt.Errorf("open templates: %w", err)
}
funcMap := template.FuncMap{
"safeHTML": func(s string) template.HTML {
return template.HTML(s) // #nosec G203 -- content is rendered from markdown by our own renderer
},
}
layoutTmpl, err := template.New("layout.html").Funcs(funcMap).ParseFS(tmplFS, "layout.html")
if err != nil {
return nil, fmt.Errorf("parse layout: %w", err)
}
pageNames := []string{"index.html", "repo.html", "doc.html", "error.html"}
pages := make(map[string]*template.Template, len(pageNames))
for _, name := range pageNames {
clone, err := layoutTmpl.Clone()
if err != nil {
return nil, fmt.Errorf("clone layout for %s: %w", name, err)
}
_, err = clone.ParseFS(tmplFS, name)
if err != nil {
return nil, fmt.Errorf("parse %s: %w", name, err)
}
pages[name] = clone
}
loadingTmpl, err := template.New("loading.html").ParseFS(tmplFS, "loading.html")
if err != nil {
return nil, fmt.Errorf("parse loading template: %w", err)
}
if cfg.Log == nil {
cfg.Log = slog.Default()
}
return &Server{
cache: cfg.Cache,
pages: pages,
loadingTmpl: loadingTmpl,
webhookSecret: cfg.WebhookSecret,
onWebhook: cfg.OnWebhook,
log: cfg.Log,
}, nil
}
// Handler returns the chi router with all routes mounted.
func (s *Server) Handler() http.Handler {
r := chi.NewRouter()
staticFS, err := fs.Sub(web.Content, "static")
if err != nil {
s.log.Error("failed to open static fs", "error", err)
} else {
r.Handle("/static/*", http.StripPrefix("/static/", http.FileServer(http.FS(staticFS))))
}
r.Get("/health", s.handleHealth)
r.Post("/webhook", s.handleWebhook)
r.Get("/", s.handleIndex)
r.Get("/{repo}/", s.handleRepo)
r.Get("/{repo}/*", s.handleDoc)
return r
}
// Breadcrumb is a navigation element.
type Breadcrumb struct {
Label string
URL string
}
// SidebarItem is a sidebar navigation entry.
type SidebarItem struct {
Label string
URL string
Active bool
}
type pageData struct {
Title string
Breadcrumbs []Breadcrumb
Sidebar []SidebarItem
LastUpdated string
// Index page
Repos []*cache.RepoInfo
// Repo page
RepoName string
RepoDescription string
Docs []*cache.Document
// Doc page
Content template.HTML
TOC []render.Heading
// Error page
Code int
Message string
}
func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
if !s.cache.IsReady() {
w.WriteHeader(http.StatusServiceUnavailable)
_, _ = w.Write([]byte("loading"))
return
}
w.WriteHeader(http.StatusOK)
_, _ = w.Write([]byte("ok"))
}
func (s *Server) handleIndex(w http.ResponseWriter, r *http.Request) {
if !s.cache.IsReady() {
s.renderLoading(w)
return
}
data := pageData{
Repos: s.cache.ListRepos(),
}
s.render(w, r, "index.html", data, http.StatusOK)
}
func (s *Server) handleRepo(w http.ResponseWriter, r *http.Request) {
if !s.cache.IsReady() {
s.renderLoading(w)
return
}
repoName := chi.URLParam(r, "repo")
repoName = sanitizePath(repoName)
repo, ok := s.cache.GetRepo(repoName)
if !ok {
s.renderError(w, r, http.StatusNotFound, "Repository not found.")
return
}
data := pageData{
Title: repo.Name,
RepoName: repo.Name,
RepoDescription: repo.Description,
Docs: repo.Docs,
Breadcrumbs: []Breadcrumb{
{Label: repo.Name, URL: "/" + repo.Name + "/"},
},
}
s.render(w, r, "repo.html", data, http.StatusOK)
}
func (s *Server) handleDoc(w http.ResponseWriter, r *http.Request) {
if !s.cache.IsReady() {
s.renderLoading(w)
return
}
repoName := chi.URLParam(r, "repo")
repoName = sanitizePath(repoName)
docPath := chi.URLParam(r, "*")
docPath = sanitizePath(docPath)
doc, ok := s.cache.GetDocument(repoName, docPath)
if !ok {
s.renderError(w, r, http.StatusNotFound, "Document not found.")
return
}
repo, _ := s.cache.GetRepo(repoName)
var sidebar []SidebarItem
if repo != nil {
for _, d := range repo.Docs {
sidebar = append(sidebar, SidebarItem{
Label: d.Title,
URL: "/" + repoName + "/" + d.URLPath,
Active: d.URLPath == docPath,
})
}
}
lastUpdated := ""
if !doc.LastUpdated.IsZero() {
lastUpdated = doc.LastUpdated.Format("2006-01-02 15:04 UTC")
}
data := pageData{
Title: doc.Title + " — " + repoName,
Content: template.HTML(doc.HTML), // #nosec G203 -- rendered by our goldmark pipeline
TOC: doc.Headings,
Sidebar: sidebar,
Breadcrumbs: []Breadcrumb{
{Label: repoName, URL: "/" + repoName + "/"},
{Label: doc.Title, URL: "/" + repoName + "/" + doc.URLPath},
},
LastUpdated: lastUpdated,
}
s.render(w, r, "doc.html", data, http.StatusOK)
}
func (s *Server) handleWebhook(w http.ResponseWriter, r *http.Request) {
if s.webhookSecret == "" {
http.Error(w, "webhook not configured", http.StatusInternalServerError)
return
}
body, err := io.ReadAll(io.LimitReader(r.Body, 1<<20))
if err != nil {
http.Error(w, "bad request", http.StatusBadRequest)
return
}
sig := r.Header.Get("X-Gitea-Signature")
if !verifyHMAC(body, sig, s.webhookSecret) {
http.Error(w, "invalid signature", http.StatusForbidden)
return
}
repoName := extractRepoName(body)
if repoName == "" {
http.Error(w, "cannot determine repo", http.StatusBadRequest)
return
}
s.log.Info("webhook received", "repo", repoName)
if s.onWebhook != nil {
go s.onWebhook(repoName)
}
w.WriteHeader(http.StatusNoContent)
}
func (s *Server) render(w http.ResponseWriter, r *http.Request, name string, data pageData, status int) {
if r.Header.Get("HX-Request") == "true" {
s.renderPartial(w, name, data, status)
return
}
tmpl, ok := s.pages[name]
if !ok {
s.log.Error("page template not found", "template", name)
http.Error(w, "internal error", http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(status)
if err := tmpl.ExecuteTemplate(w, "layout.html", data); err != nil {
s.log.Error("render template", "template", name, "error", err)
}
}
func (s *Server) renderPartial(w http.ResponseWriter, name string, data pageData, status int) {
tmpl, ok := s.pages[name]
if !ok {
s.log.Error("page template not found for partial", "template", name)
http.Error(w, "internal error", http.StatusInternalServerError)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(status)
if err := tmpl.ExecuteTemplate(w, "content", data); err != nil {
s.log.Error("render partial", "template", name, "error", err)
}
}
func (s *Server) renderLoading(w http.ResponseWriter) {
w.Header().Set("Content-Type", "text/html; charset=utf-8")
w.WriteHeader(http.StatusServiceUnavailable)
if err := s.loadingTmpl.Execute(w, nil); err != nil {
s.log.Error("render loading", "error", err)
}
}
func (s *Server) renderError(w http.ResponseWriter, r *http.Request, code int, message string) {
data := pageData{
Title: http.StatusText(code),
Code: code,
Message: message,
}
s.render(w, r, "error.html", data, code)
}
func verifyHMAC(body []byte, signature, secret string) bool {
if signature == "" {
return false
}
mac := hmac.New(sha256.New, []byte(secret))
mac.Write(body)
expected := hex.EncodeToString(mac.Sum(nil))
return hmac.Equal([]byte(expected), []byte(signature))
}
// extractRepoName pulls the repo name from a Gitea webhook JSON payload.
// We do minimal parsing to avoid importing encoding/json for a single field.
func extractRepoName(body []byte) string {
// Look for "repository":{"...", "name":"<value>"
s := string(body)
idx := strings.Index(s, `"repository"`)
if idx < 0 {
return ""
}
sub := s[idx:]
nameIdx := strings.Index(sub, `"name":"`)
if nameIdx < 0 {
return ""
}
start := nameIdx + len(`"name":"`)
end := strings.Index(sub[start:], `"`)
if end < 0 {
return ""
}
return sanitizePath(sub[start : start+end])
}
// sanitizePath removes path traversal components.
func sanitizePath(p string) string {
// Remove all .. segments before cleaning to prevent traversal.
segments := strings.Split(p, "/")
var clean []string
for _, seg := range segments {
if seg == ".." || seg == "." || seg == "" {
continue
}
clean = append(clean, seg)
}
return strings.Join(clean, "/")
}
// StartBackgroundFetch coordinates the initial fetch and periodic polling.
func StartBackgroundFetch(ctx context.Context, cfg BackgroundConfig) {
log := cfg.Log
if log == nil {
log = slog.Default()
}
// Initial fetch with retries
for {
if err := fetchAllRepos(ctx, cfg); err != nil {
log.Error("initial fetch failed, retrying in 30s", "error", err)
select {
case <-ctx.Done():
return
case <-time.After(30 * time.Second):
continue
}
}
cfg.Cache.SetReady()
log.Info("initial fetch complete")
break
}
// Poll loop
ticker := time.NewTicker(cfg.PollInterval)
defer ticker.Stop()
for {
select {
case <-ctx.Done():
return
case <-ticker.C:
if err := pollForChanges(ctx, cfg); err != nil {
log.Warn("poll failed", "error", err)
}
}
}
}
// BackgroundConfig holds configuration for background fetching.
type BackgroundConfig struct {
Cache *cache.Cache
Fetcher *Fetcher
PollInterval time.Duration
Log *slog.Logger
}