Fix of

Opening saved project removes Print Host settings #3655
Octoprint Settings when Opening a .3MF file #3244

When loading a configuration file (from AMF, 3MF, .ini or .gcode),
and if the host settings ("print_host", "printhost_apikey", "printhost_cafile")
in the configuration file is empty, then the config is considered to be anonymized,
and these anonymized keys are loaded from the referenced "derived from" profile,
if it exists in user's PrusaSlicer configuration directory.

We are aware that this is a patch work and a better long term solution
is to separate physical printer settings from logical printer settings,
but this is a good enough solution for PrusaSlicer 2.2.0 release.

src/libslic3r/Config.hpp

@@ -686,6 +686,7 @@ public:
     ConfigOption*           clone() const override { return new ConfigOptionString(*this); }
     ConfigOptionString&     operator=(const ConfigOption *opt) { this->set(opt); return *this; }
     bool                    operator==(const ConfigOptionString &rhs) const { return this->value == rhs.value; }
+    bool 					empty() const { return this->value.empty(); }
 
     std::string serialize() const override
     { 

src/slic3r/GUI/Preset.cpp

@@ -683,19 +683,51 @@ Preset& PresetCollection::load_preset(const std::string &path, const std::string
     return this->load_preset(path, name, std::move(cfg), select);
 }
 
-static bool profile_print_params_same(const DynamicPrintConfig &cfg1, const DynamicPrintConfig &cfg2)
+enum class ProfileHostParams
 {
-    t_config_option_keys diff = cfg1.diff(cfg2);
+	Same,
+	Different,
+	Anonymized,
+};
+
+static ProfileHostParams profile_host_params_same_or_anonymized(const DynamicPrintConfig &cfg_old, const DynamicPrintConfig &cfg_new)
+{
+	auto opt_print_host_old 	  = cfg_old.option<ConfigOptionString>("print_host");
+	auto opt_printhost_apikey_old = cfg_old.option<ConfigOptionString>("printhost_apikey");
+	auto opt_printhost_cafile_old = cfg_old.option<ConfigOptionString>("printhost_cafile");
+
+	auto opt_print_host_new 	  = cfg_new.option<ConfigOptionString>("print_host");
+	auto opt_printhost_apikey_new = cfg_new.option<ConfigOptionString>("printhost_apikey");
+	auto opt_printhost_cafile_new = cfg_new.option<ConfigOptionString>("printhost_cafile");
+
+	// If the new print host data is undefined, use the old data.
+	bool new_print_host_undefined = (opt_print_host_new 		== nullptr || opt_print_host_new		->empty()) &&
+									(opt_printhost_apikey_new 	== nullptr || opt_printhost_apikey_new	->empty()) &&
+									(opt_printhost_cafile_new 	== nullptr || opt_printhost_cafile_new	->empty());
+	if (new_print_host_undefined)
+		return ProfileHostParams::Anonymized;
+
+	auto opt_same = [](const ConfigOptionString *l, const ConfigOptionString *r) {
+		return ((l == nullptr || l->empty()) && (r == nullptr || r->empty())) ||
+			   (l != nullptr && r != nullptr && l->value == r->value);
+	};
+	return (opt_same(opt_print_host_old, opt_print_host_new) && opt_same(opt_printhost_apikey_old, opt_printhost_apikey_new) && 
+		    opt_same(opt_printhost_cafile_old, opt_printhost_cafile_new)) ? ProfileHostParams::Same : ProfileHostParams::Different;
+}
+
+static bool profile_print_params_same(const DynamicPrintConfig &cfg_old, const DynamicPrintConfig &cfg_new)
+{
+    t_config_option_keys diff = cfg_old.diff(cfg_new);
     // Following keys are used by the UI, not by the slicing core, therefore they are not important
     // when comparing profiles for equality. Ignore them.
     for (const char *key : { "compatible_prints", "compatible_prints_condition",
                              "compatible_printers", "compatible_printers_condition", "inherits",
                              "print_settings_id", "filament_settings_id", "sla_print_settings_id", "sla_material_settings_id", "printer_settings_id",
                              "printer_model", "printer_variant", "default_print_profile", "default_filament_profile", "default_sla_print_profile", "default_sla_material_profile",
-                             "printhost_apikey", "printhost_cafile" })
+                             "print_host", "printhost_apikey", "printhost_cafile" })
         diff.erase(std::remove(diff.begin(), diff.end(), key), diff.end());
     // Preset with the same name as stored inside the config exists.
-    return diff.empty();
+    return diff.empty() && profile_host_params_same_or_anonymized(cfg_old, cfg_new) != ProfileHostParams::Different;
 }
 
 // Load a preset from an already parsed config file, insert it into the sorted sequence of presets
@@ -724,11 +756,25 @@ Preset& PresetCollection::load_external_preset(
 		it = this->find_preset_renamed(original_name);
 		found = it != m_presets.end();
     }
-    if (found && profile_print_params_same(it->config, cfg)) {
-        // The preset exists and it matches the values stored inside config.
-        if (select)
-            this->select_preset(it - m_presets.begin());
-        return *it;
+    if (found) {
+    	if (profile_print_params_same(it->config, cfg)) {
+	        // The preset exists and it matches the values stored inside config.
+	        if (select)
+	            this->select_preset(it - m_presets.begin());
+	        return *it;
+	    }
+	    if (profile_host_params_same_or_anonymized(it->config, cfg) == ProfileHostParams::Anonymized) {
+	    	// The project being loaded is anonymized. Replace the empty host keys of the loaded profile with the data from the original profile.
+	    	// See "Octoprint Settings when Opening a .3MF file" GH issue #3244
+	    	auto opt_update = [it, &cfg](const std::string &opt_key) {
+				auto opt = it->config.option<ConfigOptionString>(opt_key);
+				if (opt != nullptr)
+					cfg.set_key_value(opt_key, opt->clone());
+	    	};
+	    	opt_update("print_host");
+	    	opt_update("printhost_apikey");
+	    	opt_update("printhost_cafile");
+	    }
     }
     // Update the "inherits" field.
     std::string &inherits = Preset::inherits(cfg);