From a0901a76dee7a455891d9b3c1a5ccd87ce0e3f71 Mon Sep 17 00:00:00 2001
From: Gergely Polonkai <gergely@polonkai.eu>
Date: Fri, 6 May 2022 13:48:03 +0200
Subject: [PATCH] [Draft] Replica

---
 earthsnake/replica/__init__.py | 96 ++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 earthsnake/replica/__init__.py

diff --git a/earthsnake/replica/__init__.py b/earthsnake/replica/__init__.py
new file mode 100644
index 0000000..23bba6e
--- /dev/null
+++ b/earthsnake/replica/__init__.py
@@ -0,0 +1,96 @@
+"""Replica related things"""
+
+from abc import ABC, abstractmethod
+from typing import List, Optional
+
+from ..document import Document
+from ..identity import Identity
+from ..path import Path
+from ..query import Query
+from ..share import Share
+
+
+class IngestEvent:
+    pass
+
+
+class Replica(ABC):
+    """A replica of a share’s data
+
+    Used to read, write, and synchronise data to.
+
+    Should be closed using the ``close()`` method when no longer being used.
+    """
+
+    def __init__(self, share: Share, **driver_kwargs):
+        pass
+
+    @property
+    @abstractmethod
+    def is_closed(self):
+        """Tells whether the replica is closed or not
+        """
+
+    @abstractmethod
+    def close(self):
+        """Closes the replica, preventing further use
+
+        Any method called after closing will return ``ReplicaIsClosedError``
+        """
+
+    @property
+    @abstractmethod
+    def max_local_index(self) -> int:
+        """Returns the maximum local index of all stored documents"""
+
+    @abstractmethod
+    def get_docs_after_local_index(self) -> List[Document]:
+        """Get all documents after a specific local index"""
+
+    @abstractmethod
+    def get_all_docs(self) -> List[Document]:
+        """Get all documents, including historical versions by other identities"""
+
+    @abstractmethod
+    def get_latest_docs(self) -> List[Document]:
+        """Get the latest from every path"""
+
+    @abstractmethod
+    def get_all_docs_at_path(self, path: Path) -> List[Document]:
+        """Get all versions of a document by different authors from a specific path"""
+
+    @abstractmethod
+    def get_latest_doc_at_path(self, path: Path) -> Optional[Document]:
+        """Get the most recent version of a document at a specific path"""
+
+    @abstractmethod
+    def query_docs(self, query: Query) -> List[Document]:
+        """Get a list of documents matching a given query"""
+
+    @abstractmethod
+    def query_paths(self, query: Query) -> List[Path]:
+        """Get all document paths where documents match a given query"""
+
+    @abstractmethod
+    def query_authors(self, query: Query) -> List[Identity]:
+        """Get all document authors where documents match a given query"""
+
+    @abstractmethod
+    def set(self, doc_to_set: Document) -> IngestEvent:
+        """Add a new document to the replica
+
+        If a document signed by the same identity exists at the same path, it will be overwritten.
+        """
+
+    @abstractmethod
+    def ingest(self, document: Document) -> IngestEvent:
+        """Ingest an existing, signed document to the replica"""
+
+    @abstractmethod
+    def overwrite_docs_by_author(self, identity: Identity) -> int:
+        """Overwrite every document from this author with an empty doc
+
+        This includes historical versions of documents.
+
+        :returns: the number of documents changed.
+        """