Refactored link finders

Mappings are now defined in a configuration file and fetched dynamically.

Change-Id: I250c22967fc66fc0aca173d4c9d65581d879b5d2
Signed-off-by: Ilia Abashin <abashinos@gmail.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/app/discover/link_finders/find_links_metadata_parser.py b/app/discover/link_finders/find_links_metadata_parser.py
new file mode 100644
index 0000000..1f28262
--- /dev/null
+++ b/app/discover/link_finders/find_links_metadata_parser.py
@@ -0,0 +1,57 @@
+from utils.metadata_parser import MetadataParser
+from utils.util import ClassResolver
+
+
+class FindLinksMetadataParser(MetadataParser):
+
+    FINDERS_FILE = "link_finders.json"
+
+    FINDERS_PACKAGE = "finders_package"
+    BASE_FINDER = "base_finder"
+    LINK_FINDERS = "link_finders"
+
+    def __init__(self):
+        super().__init__()
+        self.finders_package = None
+        self.base_finder = None
+        self.link_finders = []
+
+    def validate_link_finder(self, finder_class):
+        try:
+            module_name = ClassResolver.get_module_file_by_class_name(finder_class)
+            instance = ClassResolver\
+                .get_instance_of_class(package_name=self.finders_package,
+                                       module_name=module_name,
+                                       class_name=finder_class)
+        except ValueError:
+            instance = None
+
+        if instance:
+            self.link_finders.append(instance)
+        else:
+            self.add_error('Failed to import link finder class "{}"'
+                           .format(finder_class))
+
+    def validate_metadata(self, metadata: dict):
+        super().validate_metadata(metadata)
+        self.finders_package = metadata[self.FINDERS_PACKAGE]
+        self.base_finder = metadata[self.BASE_FINDER]
+        base_finder_module = ClassResolver\
+            .get_module_file_by_class_name(self.base_finder)
+
+        base_finder_class = ClassResolver.get_class_name_by_module(
+            ".".join((self.finders_package, base_finder_module)))
+
+        if not base_finder_class:
+            self.add_error("Couldn't find base link finder class")
+            return
+
+        for link_finder in metadata[self.LINK_FINDERS]:
+            self.validate_link_finder(finder_class=link_finder)
+        metadata[self.LINK_FINDERS] = self.link_finders
+
+        return len(self.errors) == 0
+
+    def get_required_fields(self) -> list:
+        return [self.FINDERS_PACKAGE, self.BASE_FINDER, self.LINK_FINDERS]
+