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# This module is responsible for generating elm/Gen/*.
#
# It exports an `elm_form` function to generate type definitions, a JSON
# encoder and HTML5 validation attributes to simplify and synchronize forms.
#
# It also exports an `elm_Response` function for each possible API response
# (see %apis below).
package VNWeb::Elm;
use strict;
use warnings;
use TUWF;
use Exporter 'import';
use List::Util 'max';
use VNDB::Config;
use VNDB::Types;
use VNWeb::Auth;
our @EXPORT = qw/
elm_form
/;
# API response types and arguments. To generate an API response from Perl, call
# elm_ResponseName(@args), e.g.:
#
# elm_Changed $id, $revision;
#
# These API responses are available in Elm in the `Gen.Api.Response` union type.
my %apis = (
Unauth => [], # Not authorized
Unchanged => [], # No changes
Changed => [ { id => 1 }, { uint => 1 } ], # [ id, chrev]; DB entry has been successfully changed
Success => [],
CSRF => [], # Invalid CSRF token
Invalid => [], # POST data did not validate the schema
Content => [{}], # Rendered HTML content (for markdown/bbcode APIs)
BadLogin => [], # Invalid user or pass
LoginThrottle => [], # Too many failed login attempts
InsecurePass => [], # Password is in a dictionary or breach database
BadEmail => [], # Unknown email address in password reset form
Bot => [], # User didn't pass bot verification
Taken => [], # Username already taken
DoubleEmail => [], # Account with same email already exists
DoubleIP => [], # Account with same IP already exists
BadCurPass => [], # Current password is incorrect when changing password
MailChange => [], # A confirmation mail has been sent to change a user's email address
);
# Generate the elm_Response() functions
for my $name (keys %apis) {
no strict 'refs';
$apis{$name} = [ map tuwf->compile($_), $apis{$name}->@* ];
*{'elm_'.$name} = sub {
my @args = map {
$apis{$name}[$_]->validate($_[$_])->data if tuwf->debug;
$apis{$name}[$_]->analyze->coerce_for_json($_[$_], unknown => 'reject')
} 0..$#{$apis{$name}};
tuwf->resJSON({$name, \@args})
};
push @EXPORT, 'elm_'.$name;
}
# Formatting functions
sub indent($) { $_[0] =~ s/\n/\n /gr }
sub list { indent "\n[ ".join("\n, ", @_)."\n]" }
sub string($) { '"'.($_[0] =~ s/([\\"])/\\$1/gr).'"' }
sub tuple { '('.join(', ', @_).')' }
sub bool($) { $_[0] ? 'True' : 'False' }
sub to_camel { (ucfirst $_[0]) =~ s/_([a-z])/'_'.uc $1/egr; }
# Generate a variable definition: name, type, value
sub def($$$) { sprintf "\n%s : %s\n%1\$s = %s\n", @_; }
# Generate an Elm type definition corresponding to a TUWF::Validate schema
sub def_type {
my($name, $obj) = @_;
my $data = '';
my @keys = $obj->{keys} ? grep $obj->{keys}{$_}{keys}||($obj->{keys}{$_}{values}&&$obj->{keys}{$_}{values}{keys}), sort keys $obj->{keys}->%* : ();
$data .= def_type($name . to_camel($_), $obj->{keys}{$_}{values} || $obj->{keys}{$_}) for @keys;
$data .= sprintf "\ntype alias %s = %s\n\n", $name, $obj->elm_type(
keys => +{ map +($_, ($obj->{keys}{$_}{values} ? 'List ' : '') . $name . to_camel($_)), @keys }
);
$data
}
# Generate HTML5 validation attribute lists corresponding to a TUWF::Validate schema
# TODO: Deduplicate some regexes (weburl, email)
# TODO: Throw these inside a struct for better namespacing?
sub def_validation {
my($name, $obj) = @_;
$obj = $obj->{values} if $obj->{values};
my $data = '';
$data .= def_validation($name . to_camel($_), $obj->{keys}{$_}) for $obj->{keys} ? sort keys $obj->{keys}->%* : ();
my %v = $obj->html5_validation();
$data .= def $name, 'List (Html.Attribute msg)', '[ '.join(', ',
$v{required} ? 'A.required True' : (),
$v{minlength} ? "A.minlength $v{minlength}" : (),
$v{maxlength} ? "A.maxlength $v{maxlength}" : (),
$v{min} ? 'A.min '.string($v{min}) : (),
$v{max} ? 'A.max '.string($v{max}) : (),
$v{pattern} ? 'A.pattern '.string($v{pattern}) : ()
).']' if !$obj->{keys};
$data;
}
# Generate an Elm JSON encoder taking a corresponding def_type() as input
sub encoder {
my($name, $type, $obj) = @_;
def $name, "$type -> JE.Value", $obj->elm_encoder(json_encode => 'JE.');
}
sub write_module {
my($module, $contents) = @_;
my $fn = sprintf '%s/elm/Gen/%s.elm', config->{root}, $module;
# The imports aren't necessary in all the files, but might as well add them.
$contents = <<~"EOF";
-- This file is automatically generated from lib/VNWeb/Elm.pm.
-- Do not edit, your changes will be lost.
module Gen.$module exposing (..)
import Http
import Html
import Html.Attributes as A
import Json.Encode as JE
import Json.Decode as JD
$contents
EOF
# Don't write anything if the file hasn't changed.
my $oldcontents = do {
local $/=undef; my $F;
open($F, '<:utf8', $fn) ? <$F> : '';
};
return if $oldcontents eq $contents;
open my $F, '>:utf8', $fn or die "$fn: $!";
print $F $contents;
}
# Create type definitions and a JSON encoder for a typical form.
# Usage:
#
# elm_form 'FormName', $TO_ELM_SCHEMA, $TO_SERVER_SCHEMA;
#
# That will create a Gen.FormName module with the following definitions:
#
# type alias Recv = { .. }
# type alias Send = { .. }
# encode : Send -> JE.Value
# valFieldName : List Html.Attribute
#
sub elm_form {
return if !tuwf->{elmgen};
my($name, $out, $in) = @_;
my $data = '';
$data .= def_type Recv => $out->analyze if $out;
$data .= def_type Send => $in->analyze if $in;
$data .= encoder encode => 'Send', $in->analyze if $in;
$data .= def_validation val => $in->analyze if $in;
write_module $name, $data;
}
# Generate the Gen.Api module with the Response type and decoder.
sub write_api {
# Extract all { type => 'hash' } schemas and give them their own
# definition, so that it's easy to refer to those records in other places
# of the Elm code, similar to def_type().
my(@union, @decode);
my $data = '';
my $len = max map length, keys %apis;
for (sort keys %apis) {
my($name, $schema) = ($_, $apis{$_});
my $def = $name;
my $dec = sprintf 'JD.field "%s"%s <| %s', $name,
' 'x($len-(length $name)),
@$schema == 0 ? "JD.succeed $name" :
@$schema == 1 ? "JD.map $name" : sprintf 'JD.map%d %s', scalar @$schema, $name;
my $tname = "Api$name";
for my $argn (0..$#$schema) {
my $arg = $schema->[$argn]->analyze();
my $jd = $arg->elm_decoder(json_decode => 'JD.', level => 3);
$dec .= " (JD.index $argn $jd)";
if($arg->{keys}) {
$data .= def_type $tname, $arg;
$def .= " $tname";
} elsif($arg->{values} && $arg->{values}{keys}) {
$data .= def_type $tname, $arg->{values};
$def .= " (List $tname)";
} else {
$def .= ' '.$arg->elm_type();
}
}
push @union, $def;
push @decode, $dec;
}
$data .= sprintf "\ntype Response\n = HTTPError Http.Error\n | %s\n", join "\n | ", @union;
$data .= sprintf "\ndecode : JD.Decoder Response\ndecode = JD.oneOf\n [ %s\n ]", join "\n , ", @decode;
write_module Api => $data;
};
sub write_types {
my $data = '';
$data .= def urlStatic => String => string config->{url_static};
$data .= def adminEMail => String => string config->{admin_email};
$data .= def userPerms => 'List (Int, String)' => list map tuple(VNWeb::Auth::listPerms->{$_}, string $_), sort keys VNWeb::Auth::listPerms->%*;
$data .= def skins => 'List (String, String)' =>
list map tuple(string $_, string tuwf->{skins}{$_}[0]),
sort { tuwf->{skins}{$a}[0] cmp tuwf->{skins}{$b}[0] } keys tuwf->{skins}->%*;
write_module Types => $data;
}
if(tuwf->{elmgen}) {
mkdir config->{root}.'/elm/Gen';
write_api;
write_types;
open my $F, '>', config->{root}.'/elm/Gen/.generated';
print $F scalar gmtime;
}
1;
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