gopp/server/handler.go

package server

import (
	//"github.com/d5/tengo/v2"
	"surdeus.su/util/tpp/mdx"
	//"surdeus.su/core/xgo/xmodules/htmlx"
	"surdeus.su/core/xgo/xmodules/httpx"
	"surdeus.su/core/xgo/xmodules"
	"surdeus.su/util/tpp"
	"path/filepath"
	"net/http"
	"context"
	"path"
	"mime"
	"log"
	"os"
	"io"
)

var _ = http.Handler(&Handler{})

// The type describes behaviour
// of handling stuff like in PHP.
type Handler struct {
	// THe field represents
	// where we store site's
	// source files and request handlers.
	sourcePath string
	// Preprocessor must be set by user
	// to be able to bring custom features in.
	pp *tpp.Preprocessor
	// Aditional extension. ".tpp" by default.
	// For example "file.html.tpp" will be
	// first preprocessed TPP and sent back as simple HTML.
	ext string

	// The global map accessable from all the
	// request so you can keep the states
	// between requests.
	global any
	md *mdx.Markdown
	indexSuffix string
}

// Returns the new Handler with
// specified preprocessor, source path,
// preprocessor extension and the global value.
func NewHandler(
	pp *tpp.Preprocessor,
	src, ext, index string,
	global any,
) *Handler {
	ret := &Handler{}
	ret.sourcePath = src
	ret.ext = ext
	ret.pp = pp
	ret.global = global
	ret.indexSuffix = index
	return ret
}

// Returns the default tpp.Preprocessor suitable for
// the most needs.
func DefaultPP(mod string) *tpp.Preprocessor {
	t := tpp.NewTengo().SetPreCompile(func(
		ctx context.Context,
		s *tpp.Script,
	) {
		s.SetImportDir(mod)
		s.SetImports(xmodules.Modules)
		s.EnableFileImport(true)

		s.Add("__http_request__", ctx.Value(KeyRequest))
		s.Add("__global__", ctx.Value(KeyGlobal))
		s.Add("__markdown__", ctx.Value(KeyMarkdown))
	}).SetPreCode(func(ctx context.Context) []byte {
		return []byte(`
			markdown := func(...args) {
				pp.write_raw(__markdown__(args...))
			}
			__http__ := immutable({
				request : __http_request__
			})
			context.http = __http__
			context.pp = pp
			context.global = __global__
			import("./pre")(context)
		`)
	}).SetPostCode(func(ctx context.Context) []byte {
		return []byte(`
			import("./post")(context)
		`)
	})

	return tpp.New(t)
}

func (h *Handler) SetMD(md *mdx.Markdown) *Handler {
	h.md = md
	return h
}

func (h *Handler) ServeHTTP(
	w http.ResponseWriter,
	r *http.Request,
) {
	shouldProcess := true
	urlPath := r.URL.Path
	// Cleaning URL path to prevent injections.
	urlPath = path.Clean(urlPath)
	urlExt := path.Ext(urlPath)

	filePath := filepath.Join(
		filepath.FromSlash(h.sourcePath),
		filepath.FromSlash(urlPath),
	)
	fileStat, err := os.Stat(filePath)
	if err == nil {
		if fileStat.IsDir() {
			filePath = filepath.Join(
				filePath,
				h.indexSuffix,
			)
		}
	}

	filePathTpp := filePath + h.ext
	//log.Println("pth:", urlPath, filePathTpp)
	file, err := os.Open(filePathTpp)
	if err != nil {
		shouldProcess = false
		file, err = os.Open(filePath)
		if err != nil {
			http.NotFound(w, r)
			return
		}
	}

	//process := true
	fileData, err := io.ReadAll(file)
	if err != nil {
		http.NotFound(w, r)
		return
	}

	ctx := context.WithValue(
		r.Context(),
		KeyRequest,
		&httpx.Request{
			Request: r,
		},
	)

	ctx = context.WithValue(
		ctx,
		KeyGlobal,
		h.global,
	)

	ctx = context.WithValue(
		ctx,
		KeyMarkdown,
		h.md,
	)

	// Setting before the code to let it change own
	// content type?
	contentType := mime.TypeByExtension(urlExt)
	w.Header().Set("Content-Type", contentType)
	processedData := fileData
	if shouldProcess {
		processedData, err = h.pp.Process(
			ctx,
			true,
			filePathTpp,
			fileData,
		)
		if err != nil {
			http.NotFound(w, r)
			log.Printf(
				"Error: pp.Process(...): %s\n",
				err,
			)
			return
		}
	}

	w.Write(processedData)
}