From 7d403431e354c4a24d7dfdbef3a39ab7297ae7b5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Mon, 6 Jan 2020 21:22:07 +0100
Subject: Deep copy of object to different storage

---
 include/erebos/storage.h |  7 ++++-
 src/storage.cpp          | 71 ++++++++++++++++++++++++++++++++++++++++++------
 src/storage.h            |  5 ++++
 3 files changed, 74 insertions(+), 9 deletions(-)

diff --git a/include/erebos/storage.h b/include/erebos/storage.h
index 51fa3a4..d855460 100644
--- a/include/erebos/storage.h
+++ b/include/erebos/storage.h
@@ -74,6 +74,11 @@ public:
 	Ref storeObject(const Record &) const;
 	Ref storeObject(const Blob &) const;
 
+	std::variant<Ref, std::vector<Digest>> copy(const PartialRef &) const;
+	std::variant<Ref, std::vector<Digest>> copy(const PartialObject &) const;
+	Ref copy(const Ref &) const;
+	Ref copy(const Object &) const;
+
 	template<typename T> Stored<T> store(const T &) const;
 
 	void storeKey(Ref pubref, const std::vector<uint8_t> &) const;
@@ -89,7 +94,7 @@ public:
 	static constexpr size_t size = 32;
 
 	Digest(const Digest &) = default;
-	Digest & operator=(const Digest &) = delete;
+	Digest & operator=(const Digest &) = default;
 
 	explicit Digest(std::array<uint8_t, size> value): value(value) {}
 	explicit Digest(const std::string &);
diff --git a/src/storage.cpp b/src/storage.cpp
index 2b4e027..608f82b 100644
--- a/src/storage.cpp
+++ b/src/storage.cpp
@@ -347,9 +347,40 @@ optional<Object> Storage::loadObject(const Digest & digest) const
 }
 
 Ref Storage::storeObject(const Object & object) const
+{ return copy(object); }
+
+Ref Storage::storeObject(const Record & val) const
+{ return storeObject(Object(val)); }
+
+Ref Storage::storeObject(const Blob & val) const
+{ return storeObject(Object(val)); }
+
+template<class S>
+optional<Digest> Storage::Priv::copy(const typename S::Ref & pref, vector<Digest> * missing) const
+{
+	if (backend->contains(pref.digest()))
+		return pref.digest();
+	if (pref)
+		return copy<S>(*pref, missing);
+	if (missing)
+		missing->push_back(pref.digest());
+	return nullopt;
+}
+
+template<class S>
+optional<Digest> Storage::Priv::copy(const ObjectT<S> & pobj, vector<Digest> * missing) const
 {
-	// TODO: ensure storage transitively
-	auto content = object.encode();
+	bool fail = false;
+	if (auto rec = pobj.asRecord())
+		for (const auto & item : rec->items())
+			if (auto r = item.asRef())
+				if (!copy<S>(*r, missing))
+					fail = true;
+
+	if (fail)
+		return nullopt;
+
+	auto content = pobj.encode();
 
 	array<uint8_t, Digest::size> arr;
 	int ret = blake2b(arr.data(), content.data(), nullptr,
@@ -358,15 +389,39 @@ Ref Storage::storeObject(const Object & object) const
 		throw runtime_error("failed to compute digest");
 
 	Digest digest(arr);
-	p->backend->storeBytes(digest, content);
-	return Ref::create(*this, digest).value();
+	backend->storeBytes(digest, content);
+	return digest;
 }
 
-Ref Storage::storeObject(const Record & val) const
-{ return storeObject(Object(val)); }
+variant<Ref, vector<Digest>> Storage::copy(const PartialRef & pref) const
+{
+	vector<Digest> missing;
+	if (auto digest = p->copy<PartialStorage>(pref, &missing))
+		return Ref::create(*this, *digest).value();
+	return missing;
+}
 
-Ref Storage::storeObject(const Blob & val) const
-{ return storeObject(Object(val)); }
+variant<Ref, vector<Digest>> Storage::copy(const PartialObject & pobj) const
+{
+	vector<Digest> missing;
+	if (auto digest = p->copy<PartialStorage>(pobj, &missing))
+		return Ref::create(*this, *digest).value();
+	return missing;
+}
+
+Ref Storage::copy(const Ref & ref) const
+{
+	if (auto digest = p->copy<Storage>(ref, nullptr))
+		return Ref::create(*this, *digest).value();
+	throw runtime_error("corrupted storage");
+}
+
+Ref Storage::copy(const Object & obj) const
+{
+	if (auto digest = p->copy<Storage>(obj, nullptr))
+		return Ref::create(*this, *digest).value();
+	throw runtime_error("corrupted storage");
+}
 
 void Storage::storeKey(Ref pubref, const vector<uint8_t> & key) const
 {
diff --git a/src/storage.h b/src/storage.h
index cdb8984..9e22a4a 100644
--- a/src/storage.h
+++ b/src/storage.h
@@ -103,6 +103,11 @@ struct Storage::Priv
 	shared_ptr<StorageBackend> backend;
 
 	optional<vector<uint8_t>> loadBytes(const Digest & digest) const;
+
+	template<class S>
+	optional<Digest> copy(const typename S::Ref &, vector<Digest> *) const;
+	template<class S>
+	optional<Digest> copy(const ObjectT<S> &, vector<Digest> *) const;
 };
 
 struct Ref::Priv
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