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+<?php
+/* Icinga Web 2 | (c) 2022 Icinga GmbH | GPLv2+ */
+
+namespace Icinga\Less;
+
+use Less_Parser;
+use Less_Tree_Expression;
+use Less_Tree_Rule;
+use Less_Tree_Value;
+use Less_Tree_Variable;
+use Less_VisitorReplacing;
+use LogicException;
+use ReflectionProperty;
+
+/**
+ * Replace compiled Less colors with CSS var() function calls and inject light mode calls
+ *
+ * Color replacing basically works by replacing every visited Less variable with {@link ColorPropOrVariable},
+ * which is later compiled to {@link ColorProp} if it is a color.
+ *
+ * Light mode calls are generated from light mode definitions.
+ */
+class Visitor extends Less_VisitorReplacing
+{
+ const LIGHT_MODE_CSS = <<<'CSS'
+@media (min-height: @prefer-light-color-scheme), print,
+(prefers-color-scheme: light) and (min-height: @enable-color-preference) {
+ %s
+}
+CSS;
+
+ const LIGHT_MODE_NAME = 'light-mode';
+
+ public $isPreEvalVisitor = true;
+
+ /**
+ * Whether calling var() CSS function
+ *
+ * If that's the case, don't try to replace compiled Less colors with CSS var() function calls.
+ *
+ * @var bool|string
+ */
+ protected $callingVar = false;
+
+ /**
+ * Whether defining a variable
+ *
+ * If that's the case, don't try to replace compiled Less colors with CSS var() function calls.
+ *
+ * @var false|string
+ */
+ protected $definingVariable = false;
+
+ /** @var Less_Tree_Rule If defining a variable, determines the origin rule of the variable */
+ protected $variableOrigin;
+
+ /** @var LightMode Light mode registry */
+ protected $lightMode;
+
+ /** @var false|string Whether parsing module Less */
+ protected $moduleScope = false;
+
+ /** @var null|string CSS module selector if any */
+ protected $moduleSelector;
+
+ public function visitCall($c)
+ {
+ if ($c->name !== 'var') {
+ // We need to use our own tree call class , so that we can precompile the arguments before making
+ // the actual LESS function calls. Otherwise, it will produce lots of invalid argument exceptions!
+ $c = Call::fromCall($c);
+ }
+
+ return $c;
+ }
+
+ public function visitDetachedRuleset($drs)
+ {
+ if ($this->variableOrigin->name === '@' . static::LIGHT_MODE_NAME) {
+ $this->variableOrigin->name .= '-' . substr(sha1(uniqid(mt_rand(), true)), 0, 7);
+
+ $this->lightMode->add($this->variableOrigin->name);
+
+ if ($this->moduleSelector !== false) {
+ $this->lightMode->setSelector($this->variableOrigin->name, $this->moduleSelector);
+ }
+
+ $drs = LightModeDefinition::fromDetachedRuleset($drs)
+ ->setLightMode($this->lightMode)
+ ->setName($this->variableOrigin->name);
+ }
+
+ // Since a detached ruleset is a variable definition in the first place,
+ // just reset that we define a variable.
+ $this->definingVariable = false;
+
+ return $drs;
+ }
+
+ public function visitMixinCall($c)
+ {
+ // Less_Tree_Mixin_Call::accept() does not visit arguments, but we have to replace them if necessary.
+ foreach ($c->arguments as $a) {
+ $a['value'] = $this->visitObj($a['value']);
+ }
+
+ return $c;
+ }
+
+ public function visitMixinDefinition($m)
+ {
+ // Less_Tree_Mixin_Definition::accept() does not visit params, but we have to replace them if necessary.
+ foreach ($m->params as $p) {
+ if (! isset($p['value'])) {
+ continue;
+ }
+
+ $p['value'] = $this->visitObj($p['value']);
+ }
+
+ return $m;
+ }
+
+ public function visitRule($r)
+ {
+ if ($r->name[0] === '@' && $r->variable) {
+ if ($this->definingVariable !== false) {
+ throw new LogicException('Already defining a variable');
+ }
+
+ $this->definingVariable = spl_object_hash($r);
+ $this->variableOrigin = $r;
+
+ if ($r->value instanceof Less_Tree_Value) {
+ if ($r->value->value[0] instanceof Less_Tree_Expression) {
+ if ($r->value->value[0]->value[0] instanceof Less_Tree_Variable) {
+ // Transform the variable definition rule into our own class
+ $r->value->value[0]->value[0] = new DeferredColorProp($r->name, $r->value->value[0]->value[0]);
+ }
+ }
+ }
+ }
+
+ return $r;
+ }
+
+ public function visitRuleOut($r)
+ {
+ if ($this->definingVariable !== false && $this->definingVariable === spl_object_hash($r)) {
+ $this->definingVariable = false;
+ $this->variableOrigin = null;
+ }
+ }
+
+ public function visitRuleset($rs)
+ {
+ // Method is required, otherwise visitRulesetOut will not be called.
+ return $rs;
+ }
+
+ public function visitRulesetOut($rs)
+ {
+ if ($this->moduleScope !== false
+ && isset($rs->selectors)
+ && spl_object_hash($rs->selectors[0]) === $this->moduleScope
+ ) {
+ $this->moduleSelector = null;
+ $this->moduleScope = false;
+ }
+ }
+
+ public function visitSelector($s)
+ {
+ if ($s->_oelements_len === 2 && $s->_oelements[0] === '.icinga-module') {
+ $this->moduleSelector = implode('', $s->_oelements);
+ $this->moduleScope = spl_object_hash($s);
+ }
+
+ return $s;
+ }
+
+ public function visitVariable($v)
+ {
+ if ($this->definingVariable !== false) {
+ return $v;
+ }
+
+ return (new ColorPropOrVariable())
+ ->setVariable($v);
+ }
+
+ public function visitColor($c)
+ {
+ if ($this->definingVariable !== false) {
+ // Make sure that all less tree colors do have a proper name
+ $c->name = $this->variableOrigin->name;
+ }
+
+ return $c;
+ }
+
+ public function run($node)
+ {
+ $this->lightMode = new LightMode();
+
+ $evald = $this->visitObj($node);
+
+ // The visitor has registered all light modes in visitDetachedRuleset, but has not called them yet.
+ // Now the light mode calls are prepared with the appropriate CSS selectors.
+ $calls = [];
+ foreach ($this->lightMode as $mode) {
+ if ($this->lightMode->hasSelector($mode)) {
+ $calls[] = "{$this->lightMode->getSelector($mode)} {\n$mode();\n}";
+ } else {
+ $calls[] = "$mode();";
+ }
+ }
+
+ if (! empty($calls)) {
+ // Place and parse light mode calls into a new anonymous file,
+ // leaving the original Less in which the light modes were defined untouched.
+ $parser = (new Less_Parser())
+ ->parse(sprintf(static::LIGHT_MODE_CSS, implode("\n", $calls)));
+
+ // Because Less variables are block scoped,
+ // we can't just access the light mode definitions in the calls above.
+ // The LightModeVisitor ensures that all calls have access to the environment in which the mode was defined.
+ // Finally, the rules are merged so that the light mode calls are also rendered to CSS.
+ $rules = new ReflectionProperty(get_class($parser), 'rules');
+ $rules->setAccessible(true);
+ $evald->rules = array_merge(
+ $evald->rules,
+ (new LightModeVisitor())
+ ->setLightMode($this->lightMode)
+ ->visitArray($rules->getValue($parser))
+ );
+ // The LightModeVisitor is used explicitly here instead of using it as a plugin
+ // since we only need to process the newly created rules for the light mode calls.
+ }
+
+ return $evald;
+ }
+}