rio/internal/pages/pages.go

package pages

import (
	"mime"
	"net/http"
	"strconv"
	"strings"
	"time"

	"git.polynom.me/rio/internal/constants"
	"git.polynom.me/rio/internal/context"
	"git.polynom.me/rio/internal/repo"

	"github.com/patrickmn/go-cache"
	log "github.com/sirupsen/logrus"
)

var (
	pageCache = cache.New(6*time.Hour, 1*time.Hour)
)

type PageContentCache struct {
	Content     []byte
	mimeType    string
	RequestedAt time.Time
}

func makePageContentCacheEntry(username, path string) string {
	return username + ":" + path
}

func addHeaders(csp, contentType string, contentLength int, w http.ResponseWriter) {
	// Always set a content type
	if strings.Trim(contentType, " ") == "" {
		w.Header().Set("Content-Type", "application/octet-stream")
	} else {
		w.Header().Set("Content-Type", contentType)
	}

	w.Header().Set("X-Content-Type-Options", "nosniff")
	w.Header().Set("Strict-Transport-Security", "max-age=31536000")
	w.Header().Set("Content-Length", strconv.Itoa(contentLength))

	if csp != "" {
		w.Header().Set("Content-Security-Policy", csp)
	}
}

func ServeFile(context *context.Context) {
	// Strip away a starting / as it messes with Gitea
	path := context.Path
	if path[:1] == "/" {
		path = path[1:]
	}

	key := makePageContentCacheEntry(context.Username, path)
	entry, found := pageCache.Get(key)
	var content []byte
	var mimeType string
	var err error
	var since *time.Time = nil
	if found {
		log.Debugf("Returning %s from cache", path)
		content = entry.(PageContentCache).Content
		mimeType = entry.(PageContentCache).mimeType
		sinceRaw := entry.(PageContentCache).RequestedAt
		since = &sinceRaw
	}

	content, changed, err := context.Global.Gitea.GetFile(
		context.Username,
		context.Reponame,
		constants.PagesBranch,
		path,
		since,
	)
	csp := repo.GetCSPForRepository(context.Username, context.Reponame, "", context.Global.Gitea)

	if err != nil {
		if !found {
			log.Errorf("Failed to get file %s/%s/%s (%s)", context.Username, context.Reponame, path, err)
			addHeaders(csp, "text/html", 0, context.Writer)
			context.Writer.WriteHeader(404)
		} else {
			log.Debugf("Request failed but page %s is cached in memory", path)
			addHeaders(csp, mimeType, len(content), context.Writer)
			context.Writer.WriteHeader(200)
			context.Writer.Write(content)
		}

		return
	}

	if found && !changed {
		log.Debugf("Page %s is unchanged and cached in memory", path)
		addHeaders(csp, mimeType, len(content), context.Writer)
		context.Writer.WriteHeader(200)
		context.Writer.Write(content)
		return
	}

	pathParts := strings.Split(path, ".")
	ext := pathParts[len(pathParts)-1]
	mimeType = mime.TypeByExtension("." + ext)

	now := time.Now()
	pageCache.Set(
		key,
		PageContentCache{
			content,
			mimeType,
			now,
		},
		cache.DefaultExpiration,
	)

	log.Debugf("Page %s requested from Gitea and cached in memory at %v", path, now)
	addHeaders(csp, mimeType, len(content), context.Writer)
	context.Writer.WriteHeader(200)
	context.Writer.Write(content)

	// Tell Loki about if, if desired
	if context.Global.MetricConfig.ShouldSendMetrics(path, context.UserAgent) {
		context.Global.MetricConfig.SendMetricPing(context.Domain, path, context.Referrer)
	}
}