step/http/handler.go

package http

import "log"
import "fmt"
import "path"
import "io/fs"
import "strings"
import "strconv"
import "net/http"
import "path/filepath"
import "git.tebibyte.media/sashakoshka/step"
import "git.tebibyte.media/sashakoshka/goutil/container"

type ErrorData struct {
	Status  int
	Message any
}

type Handler struct {
	Environment *step.Environment
	Directories bool
	StepExt     ucontainer.Set[string]
	Index       []string
	ErrorDocument     string
	DirectoryDocument string
}

func (this *Handler) ServeHTTP (res http.ResponseWriter, req *http.Request) {
	remoteAddr := req.RemoteAddr
	if addr := req.Header.Get("CF-Connecting-IP"); addr != "" {
		remoteAddr = fmt.Sprintf("%s --CF-> %s", addr, req.RemoteAddr)
	} else if addr := req.Header.Get("X-Forwarded-For"); addr != "" {
		remoteAddr = fmt.Sprintf("%s --??-> %s", addr, req.RemoteAddr)
	}
	log.Println("(i)", req.Method, req.URL, "from", remoteAddr)
	filesystem := this.Environment.GetFS()

	// normalize path
	pat := req.URL.Path
	if !strings.HasPrefix(pat, "/") {
		pat = "/" + pat
		req.URL.Path = pat
	}
	hasTrailingSlash := strings.HasSuffix(pat, "/")
	pat = path.Clean(req.URL.Path)

	info, err := statFile(filesystem, pathToName(pat))
	if err != nil {
		this.serveError(res, req, http.StatusNotFound, req.URL, false)
		return
	}
	if info.IsDir() {
		// ensure the path ends with a /
		if !hasTrailingSlash {
			http.Redirect(res, req, pat + "/", http.StatusMovedPermanently)
			return
		}
	
		// try to find an index
		for _, base := range this.Index {
			currentPath := path.Join(pat, base)
			info, err := statFile(filesystem, pathToName(currentPath))
			if err != nil   { continue }
			if info.IsDir() { continue }
			this.serveFile(res, req, currentPath)
			return
		}

		if !this.Directories {
			this.serveError(res, req, http.StatusForbidden, req.URL, false)
			return
		}

		// TODO: serve a directory and return
		// have a custom directory listing document that takes in a list
		// of the files in the directory and the path to the directory
		// as data
	}

	this.serveFile(res, req, pat)
}

func (this *Handler) serveFile (
	res http.ResponseWriter,
	req *http.Request,
	pat string,
) {
	name := pathToName(pat)
	if !this.StepExt.Has(filepath.Ext(name)) {
		// just a normal file
		http.ServeFileFS(res, req, this.Environment.GetFS(), name)
		return
	}
	this.serveDocument(res, req, name)	
}

func (this *Handler) serveDocument (
	res http.ResponseWriter,
	req *http.Request,
	name string,
) {
	// parse
	document, err := this.Environment.Parse(name)
	if err != nil {
		this.serveError(res, req, http.StatusInternalServerError, err, false)
		return
	}

	// set up HTTP response recorder
	recorder := HTTPResponseRecorder { }
	resetRecorder := func () {
		recorder.Reset()
		recorder.Head = res.Header().Clone()
	}
	if contentType, ok := document.Meta["content-type"]; ok {
		recorder.Header().Set("Content-Type", contentType)
	}
	if status, ok := document.Meta["status"]; ok {
		if status, err := strconv.Atoi(status); err == nil {
			recorder.Status = status
		}
	}

	// execute document
	data := HTTPData { }
	data.Res = WrappedResponseWriter {
		responseWriter: &recorder,
		resetFunc: resetRecorder,
		Header: WrappedHeader {
			Header: recorder.Header(),
		},
	}
	data.Req = req
	err = document.Execute(&recorder, step.ExecutionData {
		Data: data,
	})
	if err != nil {
		this.serveError(res, req, http.StatusInternalServerError, err, false)
		return
	}

	// play back recorded response
	err = recorder.Play(res)
	if err != nil {
		this.logErr(name, err)
	}
}

func (this *Handler) serveError (
	res http.ResponseWriter,
	req *http.Request,
	status int,
	message any,
	safeMode bool,
) {
	log.Printf("ERR %d %s: %v\n", status, http.StatusText(status), message)
	if safeMode || this.ErrorDocument == "" {
		res.Header().Add("Content-Type", "text/plain")
		res.WriteHeader(status)
		// TODO: allow customization with templates
		if message == nil {
			fmt.Fprintf(res, "%d %s\n", status, http.StatusText(status))
		} else {
			fmt.Fprintf(res, "%d %s: %v\n", status, http.StatusText(status), message)
		}
		return
	}

	document, err := this.Environment.Parse(this.ErrorDocument)
	if err != nil {
		this.serveError(res, req, http.StatusInternalServerError, err, true)
		return
	}
	err = document.Execute(res, step.ExecutionData {
		Data: ErrorData {
			Status:  status,
			Message: message,
		},
	})
	if err != nil {
		this.serveError(res, req, http.StatusInternalServerError, err, true)
		return
	}
}

func (this *Handler) logErr (name string, err error) {
	log.Printf("ERR %s: %v\n", name, err)
}

func statFile (filesystem fs.FS, name string) (fs.FileInfo, error) {
	if filesystem, ok := filesystem.(fs.StatFS); ok {
		return filesystem.Stat(name)
	}
	file, err := filesystem.Open(name)
	if err != nil { return nil, err }
	defer file.Close()
	return file.Stat()
}

func pathToName (pat string) string {
	if strings.HasPrefix(pat, "/") {
		pat = strings.TrimPrefix(pat, "/")
	}
	if pat == "" {
		return "."
	}
	return pat
}