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

package ui

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

	"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/auth"
	"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)
					},

					// strings
					"lowerSnakeCase": func(s string) string {
						return strings.ToLower(strings.Join(strings.Split(s, " "), "_"))
					},
					"splitSnakeCase": func(s string) string {
						return strings.Join(strings.Split(s, "_"), " ")
					},
					"capitalize": func(s string) string {
						ss := strings.Split(s, " ")
						us := make([]string, len(ss))
						for i, v := range ss {
							if len(v) == 0 {
								us[i] = v
							} else {
								us[i] = strings.ToUpper(v[:1]) + v[1:]
							}
						}
						return strings.Join(us, " ")
					},
					"hasPrefix": func(s, prefix string) bool {
						return strings.HasPrefix(s, prefix)
					},

					// 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
					},

					// html
					"rawHTML": func(s string) template.HTML {
						return template.HTML(s)
					},
					"rawHTMLAttr": func(s string) template.HTMLAttr {
						return template.HTMLAttr(s)
					},
					"style": func(kvs ...string) (template.HTMLAttr, error) {
						if len(kvs)%2 != 0 {
							return "", fmt.Errorf("expected an even number of keys: %d", len(kvs))
						}
						parts := make([]string, len(kvs)/2)
						for i := range parts {
							parts[i] = fmt.Sprintf("%s: %s;", kvs[2*i], kvs[2*i+1])
						}
						return template.HTMLAttr(strings.Join(parts, " ")), nil
					},

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

					// slices
					"newSlice": func(args ...any) []any {
						return args
					},
					"newHTMLSlice": func(args ...string) []template.HTML {
						ss := make([]template.HTML, len(args))
						for i, s := range args {
							ss[i] = template.HTML(s)
						}
						return ss
					},
				}
			},
		}),
		rawEvents: rawEvents,
		accts:     accts,
		etsy:      etsy,
	}

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

func (s *webpageRouter) redirectToAccountsIfLoggedInWithAnAccount(c *gin.Context) (response.Response, error) {
	id := auth.GetIdentity(c)
	if id.Account == nil || id.Account.AccountID == 0 {
		return nil, nil
	}

	return response.TemporaryRedirect(fmt.Sprintf("%s/accounts/%d", s.uiPath, id.Account.AccountID)), nil
}

// 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",
		auth.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 := auth.GetIdentity(r.Context())
	if id.Account == nil || id.Account.AccountID != acctID {
		return response.Unauthorized().
			HTML([]byte(fmt.Sprintf(`
<section class="text-center">
	<header class="m-[1em]">
		<h2>
			Access Not Granted
		</h2>

		<a href="/ui%s" class="block m-[1em]">
			<code>
				/ui%s
			</code>
		</a>
	</header>

	<div class="m-[2em]">
		<p class="italic font-bold">
			Sorry, you don't have access to the given page.
		</p>
	</div>
</section>

<section class="text-center">
	<a href="/">
		Return to app
	</a>
</section>
			`, r.URL, r.URL)))
	}

	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
}