inventory-plus-plus/internal/server/templates.go

package server

import (
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"strconv"
	"strings"

	"ruben/inventory2/internal/server/middleware"
	"ruben/inventory2/internal/server/response"
)

// GET /
// compiles the page template or component template matching the url
func (s *Server) serveTemplates(r *http.Request) (response.Response, error) {
	name, args := s.getTemplateNameAndArgs(r, "internal/site/templates/component_bodies")

	b, err := s.templater.ExecuteComponentBody(name, args...)
	if err == nil {
		return response.HTML(b), nil
	}

	if !isFileNotFoundError(err) {
		return s.handleTemplateError(err, args...)
	}

	name, args = s.getTemplateNameAndArgs(r, "internal/site/templates/page_bodies")

	if b, err = s.templater.ExecutePage(name, args...); err == nil {
		return response.HTML(b), nil
	}

	return s.handleTemplateError(err, args...)
}

func (s *Server) getTemplateNameAndArgs(r *http.Request, templateDir string) (name string, args []any) {
	ctx := r.Context()
	name, pathParams := getTemplateNameForURL(r.URL, templateDir)

	return name, []any{
		"Request",
		r,
		// add services and data here
		"RawEvents",
		s.rawEvents.WithContext(ctx),
		"URLCalc",
		newURLCalculator(r.URL),
		"PathParams",
		pathParams,
		"Accounts",
		s.accts.WithContext(ctx),
		"Etsy",
		s.etsy.WithContext(ctx),

		// TODO: apply auth to all templates needed!
		// auth tooling
		/*
			AccessToken string
			Claims      authentication.AccessTokenClaims
			User        accounts.OAuthUser
			Account     *accounts.Account
		*/
		"Identity",
		middleware.GetIdentity(r.Context()),
		"Auth",
		newTemplateAuthenticator(r),
	}
}

// TODO: clean this up...
// TODO: somehow tell what the path params are and pass them up.
//   - then consider pushing this functionality into the template library.
//
// getComponentTemplateNameForURL eliminate any trailing .html or /, and checks for any
// file with path parameters in the name, eg '{abc}.html.tmpl', prefering exact filename matches.
func getTemplateNameForURL(u *url.URL, templateDir string) (name string, params map[string]string) {
	fp := strings.TrimPrefix(strings.TrimSuffix(strings.TrimSuffix(u.Path, ".html"), "/"), "/")
	if fp == "" {
		// "/" maps to "/index"
		fp = "index"
	}

	fpParts := strings.Split(fp, "/")
	res := getMatchingGlobPatternsCapturingFilepathIncludingParametrizedFilepaths(fpParts)
	for _, combs := range res {
		pattern := path.Join(templateDir, path.Join(combs...)) + ".html.tmpl"

		matches, _ := filepath.Glob(pattern)
		if len(matches) == 0 {
			pattern := path.Join(templateDir, path.Join(combs...), "index") + ".html.tmpl"
			matches, _ = filepath.Glob(pattern)
		}
		if len(matches) > 0 {
			match := matches[0]
			name = strings.TrimPrefix(strings.TrimSuffix(match, ".html.tmpl"), templateDir+"/")

			patternParts := strings.Split(name, "/")
			params = make(map[string]string)
			for i, pp := range patternParts {
				if strings.HasPrefix(pp, "{") && strings.HasSuffix(pp, "}") {
					params[pp[1:len(pp)-1]] = fpParts[i]
				}
			}

			return name, params
		}
	}

	return fp, nil
}

func getMatchingGlobPatternsCapturingFilepathIncludingParametrizedFilepaths(filepathParts []string) [][]string {
	switch len(filepathParts) {
	case 0:
		return nil
	case 1:
		return [][]string{
			[]string{filepathParts[0]},
			[]string{"{*}"},
		}
	default:
		tailCombs := getMatchingGlobPatternsCapturingFilepathIncludingParametrizedFilepaths(filepathParts[1:])

		combs := make([][]string, 2*len(tailCombs))
		for i, c := range tailCombs {
			combs[i*2] = append([]string{filepathParts[0]}, c...)
			combs[i*2+1] = append([]string{"{*}"}, c...)
		}

		return combs
	}
}

func (s *Server) handleTemplateError(err error, templateArgs ...any) (response.Response, error) {
	if isFileNotFoundError(err) {
		return nil, response.NotFound().
			Wrap(err).
			Msg("resource not found")
	}

	return nil, err
}

func isFileNotFoundError(err error) bool {
	var pe *os.PathError
	isPathErr := errors.As(err, &pe)

	return isPathErr && pe.Err != nil && pe.Err.Error() == "no such file or directory"
}

func getHTTPStatusCode(err error) int {
	rerr, ok := response.GetError(err)
	if !ok {
		return http.StatusInternalServerError
	}

	code, ok := rerr.GetStatus()
	if !ok {
		return http.StatusInternalServerError
	}

	return code
}

// template tooling

type URLCalculator struct {
	url *url.URL
}

func newURLCalculator(u *url.URL) URLCalculator {
	cpy := *u
	return URLCalculator{
		url: &cpy,
	}
}

func (c URLCalculator) SetQueryParam(k string, v any) string {
	u := *c.url
	q := u.Query()
	q.Set(k, fmt.Sprint(v))
	u.RawQuery = q.Encode()

	return u.String()
}

// template authenticator

type templateAuthenticator struct {
	req *http.Request
}

func newTemplateAuthenticator(req *http.Request) *templateAuthenticator {
	return &templateAuthenticator{
		req: req,
	}
}

// templateAuthorizationFunc these shouild always return an empty string
type templateAuthorizationFunc = func() (string, error)

func (a *templateAuthenticator) ByMatchingAccountID(acctIDPathPosition int) (string, error) {
	return "", authorizeByMatchingAccountID(a.req, acctIDPathPosition)
}

func authorizeByMatchingAccountID(r *http.Request, acctIDPathPosition int) error {
	pathParts := strings.Split(strings.TrimSuffix(strings.TrimPrefix(r.URL.Path, "/"), "/"), "/")
	if len(pathParts) < acctIDPathPosition {
		return fmt.Errorf("authorization failed due to unexpected path: %s", r.URL.Path)
	}

	part := pathParts[acctIDPathPosition-1]
	acctID, err := strconv.ParseInt(part, 10, 64)
	if err != nil {
		return response.NotFound().
			Msgf("account does not exist: %s", part)
	}

	id := middleware.GetIdentity(r.Context())
	if id.Account == nil || id.Account.AccountID != acctID {
		return response.Unauthorized().
			Msgf("user does not have access to account %d", acctID)
	}

	return nil
}