inventory-plus-plus/internal/server/ui/router.go

package ui

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"text/template"

	"ruben/inventory2/internal/domains/accounts"
	etsy_platform "ruben/inventory2/internal/domains/platforms/etsy"
	"ruben/inventory2/internal/domains/raw_events"
	"ruben/inventory2/internal/logging"
	"ruben/inventory2/internal/server/middleware"
	"ruben/inventory2/internal/server/response"

	"github.com/angelbeltran/templater"
	"github.com/gin-gonic/gin"
)

type (
	webpageRouter struct {
		log       *logging.Logger
		uiPath    string
		templater *templater.Templater
		rawEvents *raw_events.Store
		accts     *accounts.Store
		etsy      *etsy_platform.Platform
	}

	// ErrTemplateNotFound is returned if the reason the template failed to compile
	// is due to the template not being found.
	ErrTemplateNotFound struct {
		err error
	}
)

func Routes(
	logger *logging.Logger,
	r gin.IRoutes,
	uiPath string,
	rawEvents *raw_events.Store,
	accts *accounts.Store,
	etsy *etsy_platform.Platform,
	authenticate gin.HandlerFunc,
) {

	s := &webpageRouter{
		log:    logger,
		uiPath: uiPath,
		templater: new(templater.Templater).With(templater.Config{
			Funcs: func(name string, props map[string]any) template.FuncMap {
				return template.FuncMap{
					// parsing
					"parseInt": func(s string) (int, error) {
						return strconv.Atoi(s)
					},
					"parseInt64": func(s string) (int64, error) {
						return strconv.ParseInt(s, 10, 64)
					},
					"parsePlatform": func(s string) (accounts.Platform, error) {
						return accounts.NewPlatform(s)
					},

					// arithmetic
					"addInt": func(a, b int) int {
						return a + b
					},
					"subInt": func(a, b int) int {
						return a - b
					},
					"multInt": func(a, b int) int {
						return a * b
					},

					// json
					"prettyPrintJSON": func(j json.RawMessage) string {
						b, err := json.MarshalIndent(j, " ", "")
						if err != nil {
							return string(j)
						}
						return string(b)
					},
					"marshalJSON": json.Marshal,
				}
			},
		}),
		rawEvents: rawEvents,
		accts:     accts,
		etsy:      etsy,
	}

	r.GET("", response.Handler(s.serveTemplate))
	r.GET("/*rest", authenticate, response.Handler(s.serveTemplate))
}

// GET /
// compiles the page template or component template matching the url
func (s *webpageRouter) serveTemplate(c *gin.Context) (response.Response, error) {
	// trim the url path prefix before loading the templates
	c.Request.URL.Path = c.Request.URL.Path[len(s.uiPath):]
	defer func() {
		c.Request.URL.Path = s.uiPath + c.Request.URL.Path
	}()

	r := c.Request
	ctx := r.Context()

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

		// auth tooling
		"Identity",
		middleware.GetIdentity(ctx),
		"Auth",
		newTemplateAuthenticator(r),
	}

	b, err := s.templater.Execute(strings.Trim(r.URL.Path, "/"), args...)
	if err != nil {
		if isFileNotFoundError(err) || isInvalidWildcardValue(err) {
			werr := response.NotFound().
				Wrap(ErrTemplateNotFound{
					err: err,
				}).
				Msg("resource not found")

			nfb, nferr := s.templater.Execute("not-found", args...)
			if nferr != nil {
				s.log.Errorf("failed to render not-found page: %v", nferr)
				return nil, werr
			}

			return nil, werr.
				HTML(nfb)
		}

		return nil, err
	}

	return response.HTML(b), nil
}

func isInvalidWildcardValue(err error) bool {
	var te *templater.ErrInvalidWildcardValue
	return errors.As(err, &te)
}

func isFileNotFoundError(err error) bool {
	var te *templater.ErrNotTemplateFileFound
	return errors.As(err, &te)
}

// 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
}

func (e ErrTemplateNotFound) Error() string {
	if e.err != nil {
		return fmt.Sprintf("template not found: %v", e.err)
	}
	return fmt.Sprintf("template not found")
}

func (e ErrTemplateNotFound) Unwrap() error {
	return e.err
}