WIP

1 files changed, 120 insertions, 0 deletions

diff --git a/repository/common.go b/repository/common.go
new file mode 100644
index 00000000..7fd7ae19
--- /dev/null
+++ b/repository/common.go
@@ -0,0 +1,120 @@
+package repository
+
+import (
+	"io"
+
+	"golang.org/x/crypto/openpgp"
+	"golang.org/x/crypto/openpgp/armor"
+	"golang.org/x/crypto/openpgp/errors"
+)
+
+// nonNativeMerge is an implementation of a branch merge, for the case where
+// the underlying git implementation doesn't support it natively.
+func nonNativeMerge(repo RepoData, ref string, otherRef string, treeHashFn func() Hash) error {
+	commit, err := repo.ResolveRef(ref)
+	if err != nil {
+		return err
+	}
+
+	otherCommit, err := repo.ResolveRef(otherRef)
+	if err != nil {
+		return err
+	}
+
+	if commit == otherCommit {
+		// nothing to merge
+		return nil
+	}
+
+	// fast-forward is possible if otherRef include ref
+
+	otherCommits, err := repo.ListCommits(otherRef)
+	if err != nil {
+		return err
+	}
+
+	fastForwardPossible := false
+	for _, hash := range otherCommits {
+		if hash == commit {
+			fastForwardPossible = true
+			break
+		}
+	}
+
+	if fastForwardPossible {
+		return repo.UpdateRef(ref, otherCommit)
+	}
+
+	// fast-forward is not possible, we need to create a merge commit
+
+	// we need a Tree to make the commit, an empty Tree will do
+	emptyTreeHash, err := repo.StoreTree(nil)
+	if err != nil {
+		return err
+	}
+
+	newHash, err := repo.StoreCommit(emptyTreeHash, commit, otherCommit)
+	if err != nil {
+		return err
+	}
+
+	return repo.UpdateRef(ref, newHash)
+}
+
+// nonNativeListCommits is an implementation for ListCommits, for the case where
+// the underlying git implementation doesn't support if natively.
+func nonNativeListCommits(repo RepoData, ref string) ([]Hash, error) {
+	var result []Hash
+
+	stack := make([]Hash, 0, 32)
+	visited := make(map[Hash]struct{})
+
+	hash, err := repo.ResolveRef(ref)
+	if err != nil {
+		return nil, err
+	}
+
+	stack = append(stack, hash)
+
+	for len(stack) > 0 {
+		// pop
+		hash := stack[len(stack)-1]
+		stack = stack[:len(stack)-1]
+
+		if _, ok := visited[hash]; ok {
+			continue
+		}
+
+		// mark as visited
+		visited[hash] = struct{}{}
+		result = append(result, hash)
+
+		commit, err := repo.ReadCommit(hash)
+		if err != nil {
+			return nil, err
+		}
+
+		for _, parent := range commit.Parents {
+			stack = append(stack, parent)
+		}
+	}
+
+	// reverse
+	for i, j := 0, len(result)-1; i < j; i, j = i+1, j-1 {
+		result[i], result[j] = result[j], result[i]
+	}
+
+	return result, nil
+}
+
+// deArmorSignature convert an armored (text serialized) signature into raw binary
+func deArmorSignature(armoredSig io.Reader) (io.Reader, error) {
+	block, err := armor.Decode(armoredSig)
+	if err != nil {
+		return nil, err
+	}
+	if block.Type != openpgp.SignatureType {
+		return nil, errors.InvalidArgumentError("expected '" + openpgp.SignatureType + "', got: " + block.Type)
+	}
+	return block.Body, nil
+}