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

package site

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"ruben/inventory2/internal/site/response"
	"strings"
)

// GET /
func (s *Server) serveTemplates(r *http.Request) (response.Response, error) {
	ctx := r.Context()
	name, pathParams := getPageTemplateNameForURL(r.URL)

	templateArgs := []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",
		getIdentity(r.Context()),
		"Auth",
		newTemplateAuthenticator(r),
	}

	b, err := s.templater.ExecutePage(name, templateArgs...)
	if err != nil {
		return s.handleTemplateError(err, templateArgs...)
	}

	return response.Body(io.NopCloser(bytes.NewBuffer(b))), nil
}

// 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.
//
// getPageTemplateNameForURL 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 getPageTemplateNameForURL(u *url.URL) (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 {
		const pageBodiesPrefix = "internal/site/templates/page_bodies"
		pattern := path.Join(pageBodiesPrefix, path.Join(combs...)) + ".html.tmpl"

		matches, _ := filepath.Glob(pattern)
		if len(matches) == 0 {
			pattern := path.Join(pageBodiesPrefix, 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"), pageBodiesPrefix+"/")

			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) {
	code := getHTTPStatusCode(err)

	if code == http.StatusNotFound ||
		code == http.StatusForbidden ||
		code == http.StatusUnauthorized ||
		isFileNotFoundError(err) {

		b, err := s.templater.ExecutePage("not-found", templateArgs...)
		if err != nil {
			fmt.Println("failed to render not found page:", err)
			return nil, response.NotFound().
				Wrap(err).
				Msg("resource not found")
		}

		return response.Body(io.NopCloser(bytes.NewBuffer(b))), nil
	}

	if code == http.StatusConflict {
		b, err := s.templater.ExecutePage("conflict", templateArgs...)
		if err != nil {
			fmt.Println("failed to render conflict page:", err)
			return nil, response.Conflict().
				Wrap(err).
				Msg("conflict")
		}

		return response.Body(io.NopCloser(bytes.NewBuffer(b))), nil
	}

	return nil, fmt.Errorf("failed to render page: %w", 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)
}