Although it is possible to just print the invoice from the browser, many
people will not even try an assume that they can not create a PDF for
the invoice.
I thought of using Groff or TeX to create the PDF, but it would mean
maintaining two templates in two different systems (HTML and whatever i
would use), and would probably look very different, because i do not
know Groff or TeX that well.
I wish there was a way to tell the browser to print to PDF, and it can
be done, but only with the Chrome Protocol to a server-side running
Chrome instance. This works, but i would need a Chrome running as a
daemon.
I also wrote a Qt application that uses QWebEngine to print the PDF,
much like wkhtmltopdf, but with support for more recent HTML and CSS
standards. Unfortunately, Qt 6.4’s embedded Chromium does not follow
break-page-inside as well as WeasyPrint does.
To use WeasyPrint, at first i wanted to reach the same URL as the user,
passing the cookie to WeasyPrint so that i can access the same invoice
as the user, something that can be done with wkhtmltopdf, but WeasyPrint
does not have such option. I did it with a custom Python script, but
then i need to package and install that script, that is not that much
work, but using the Debian-provided script is even less work, and less
likely to drift when WeasyPrint changes API.
Also, it is unnecessary to do a network round-trip from Go to Python
back to Go, because i can already write the invoice HTML as is to
WeasyPrint’s stdin.
Since users do not have access to the auth scheme, i had to add a view
that selects only the data that they can see of themselves (i.e., no
password or cookie).
I wanted to use the `request.user.id` setting that i set in
check_cookie, but this would be bad because anyone can change that
parameter and, since the view is created by the owner, could see and
*change* the values of everyone just by knowing their id. Thus, now i
use the cookie instead, because it is way harder to figure out, and if
you already have it you can just set to your browser and the user is
fucked anyway; the database can not help here.
I **am** going to use the user id in row level security policies, but
not the value coming for the setting but instaed the one in the
`user_profile`, since it already is “derived” from the cookie, that’s
why i added that column to the view.
The profile includes the language, that i do not use it yet to switch
the locale, so i had to add a relation of the available languages, for
constraint purposes. There is no NULL language, and instead i added the
“Undefined” language, with ‘und’ tag’, to represent “do not know/use
content negotiation”.
The languages in that relation are the same i used to have inside
locale.go, because there is no point on having options for languages i
do not have the translation for, so i now configure the list of
available languages user in content negotiation from that relation.
Finally, i have added all font from RemixIcon because that’s what we
used in the design and i am going to use quite a lot of them.
There is duplication in the views; i will address that in a different
commit.
I had to choose between [1], [2], and [3].
As far as i could find, [1] is not easy to work with templates[4] and at
the moment is not maintained[5].
Both [2] and [3] use the same approach to be used from within templates:
you have to define a FuncMap with template functions that call the
message catalog. Also, both libraries seems to be reasonably
maintained, and have packages in Debian’s repository.
However, [2] repeats the same mistakes that POSIX did with its
catalogs—using identifiers that are not the strings in the source
language—, however this time the catalogs are written in JSON or YAML!
This, somehow, makes things worse….
[3], the one i settled with, is fine and decently maintained. There are
some surprising things, such as to be able to use directly the PO file,
and that it has higher priority over the corresponding MO, or that the
order of parameters is reversed in respect to gettext. However, it uses
a saner format, and is a lot easier to work with than [3].
The problem, of course, is that xgettext does not know how to find
translatable strings inside the template. [3] includes a CLI tool
similar to xgettext, but is not a drop-in replacement[6] and does not
process templates.
The proper way to handle this would be to add a parser to xgettext, but
for now i found out that if i surround the call to the translation
functions from within the template with parentheses, i can trick
xgettext into believing it is parsing Scheme code, and extracts the
strings successfully—at least, for what i have tried. Had to add the
keyword for pgettext, because Schemed does not have it, but at least i
can do that with command line parameters.
For now i left only Spanish and Catalan as the two available languages,
even though the source text is written in English, because that way i
can make sure i do not leave strings untranslated.
[1]: https://golang.org/x/text
[2]: https://github.com/nicksnyder/go-i18n
[3]: https://github.com/leonelquinteros/gotext
[4]: https://github.com/golang/go/issues/39954
[5]: https://github.com/golang/go/issues/12750
[6]: https://github.com/leonelquinteros/gotext/issues/38
According to the de facto project layout for Go[0], these files should
go into a build/package folder, but since i already broke the rules with
Sqitch’s folders, i do not see why i have to go against Debian’s
conventions of putting it into a debian subfolder of the root.
[0]: https://github.com/golang-standards/project-layout
jordi fita mas