implement git commit

SwiftGit2/Objects.swift

@@ -8,6 +8,7 @@
 
 import Foundation
 import libgit2
+import Result
 
 /// A git object.
 public protocol ObjectType {
@@ -37,6 +38,14 @@ public struct Signature {
 	/// The time zone that `time` should be interpreted relative to.
 	public let timeZone: TimeZone
 	
+	/// Create an instance with custom name, email, dates, etc.
+	public init(name: String, email: String, time: Date = Date.init(), timeZone: TimeZone = TimeZone.autoupdatingCurrent) {
+		self.name = name
+		self.email = email
+		self.time = time
+		self.timeZone = timeZone
+	}
+
 	/// Create an instance with a libgit2 `git_signature`.
 	public init(_ signature: git_signature) {
 		name = String(validatingUTF8: signature.name)!
@@ -44,6 +53,20 @@ public struct Signature {
 		time = Date(timeIntervalSince1970: TimeInterval(signature.when.time))
 		timeZone = TimeZone(secondsFromGMT: 60 * Int(signature.when.offset))!
 	}
+
+	/// Return an unsafe pointer to the `git_signature` struct.
+	/// Caller is responsible for freeing it with `git_signature_free`.
+	var unsafeSignature: Result<UnsafeMutablePointer<git_signature>, NSError> {
+		var signature: UnsafeMutablePointer<git_signature>? = nil
+		let time = git_time_t(self.time.timeIntervalSince1970)	// Unix epoch time
+		let offset: Int32 = 0
+		let signatureResult = git_signature_new(&signature, name, email, time, offset)
+		guard signatureResult == GIT_OK.rawValue, let signatureUnwrap = signature else {
+			let err = NSError(gitError: signatureResult, pointOfFailure: "git_signature_new")
+			return .failure(err)
+		}
+		return .success(signatureUnwrap)
+	}
 }
 
 extension Signature: Hashable {

SwiftGit2/Repository.swift

@@ -601,15 +601,96 @@ final public class Repository {
 		var paths = git_strarray(strings: &dirPointer, count: 1)
 		return unsafeIndex().flatMap { index in
 			defer { git_index_free(index) }
-			let add_result = git_index_add_all(index, &paths, 0, nil, nil)
-			guard add_result == GIT_OK.rawValue else {
-				let err = NSError(gitError: add_result, pointOfFailure: "git_index_add_all")
+			let addResult = git_index_add_all(index, &paths, 0, nil, nil)
+			guard addResult == GIT_OK.rawValue else {
+				let err = NSError(gitError: addResult, pointOfFailure: "git_index_add_all")
 				return .failure(err)
 			}
 			return .success(())
 		}
 	}
 
+	/// Perform a commit with arbitrary numbers of parent commits.
+	public func commit(
+		tree treeOID: git_oid,
+		parents: [Commit],
+		message: String,
+		signature: Signature
+	) -> Result<Commit, NSError> {
+		return unsafeIndex().flatMap { index in
+			defer { git_index_free(index) }
+    		// create commit signature
+			return signature.unsafeSignature.flatMap { signature in
+				defer { git_signature_free(signature) }
+				var tree: OpaquePointer? = nil
+				var treeOIDCopy = treeOID
+				let lookupResult = git_tree_lookup(&tree, self.pointer, &treeOIDCopy)
+				guard lookupResult == GIT_OK.rawValue else {
+					let err = NSError(gitError: lookupResult, pointOfFailure: "git_tree_lookup")
+					return .failure(err)
+				}
+				defer { git_tree_free(tree) }
+
+				var msgBuf = git_buf()
+				git_message_prettify(&msgBuf, message, 0, /* ascii for # */ 35)
+				defer { git_buf_free(&msgBuf) }
+
+				// use HEAD as parent
+				var parentC: [OpaquePointer?] = []
+				for parentCommit in parents {
+					var parent: OpaquePointer? = nil
+					var oid = parentCommit.oid.oid
+					git_commit_lookup(&parent, self.pointer, &oid)
+					parentC.append(parent!)
+				}
+
+				let parentsContiguous = ContiguousArray(parentC)
+				return parentsContiguous.withUnsafeBufferPointer { unsafeBuffer in
+					var commitOID = git_oid()
+					let parentsPtr = UnsafeMutablePointer(mutating: unsafeBuffer.baseAddress)
+					let result = git_commit_create(
+						&commitOID,
+						self.pointer,
+						"HEAD",
+						signature,
+						signature,
+						nil,
+						msgBuf.ptr,
+						tree,
+						parents.count,
+						parentsPtr
+					)
+					guard result == GIT_OK.rawValue else {
+						return .failure(NSError(gitError: result, pointOfFailure: "git_commit_create"))
+					}
+					return commit(OID(commitOID))
+				}
+			}
+		}
+	}
+
+	/// Perform a commit of the staged files with the specified message and signature,
+	/// assuming we are not doing a merge and using the current tip as the parent.
+	public func commit(message: String, signature: Signature) -> Result<Commit, NSError> {
+		return unsafeIndex().flatMap { index in
+			defer { git_index_free(index) }
+			var treeOID = git_oid()
+			let treeResult = git_index_write_tree(&treeOID, index)
+			guard treeResult == GIT_OK.rawValue else {
+				let err = NSError(gitError: treeResult, pointOfFailure: "git_index_write_tree")
+				return .failure(err)
+			}
+			var parentID = git_oid()
+			let nameToIDResult = git_reference_name_to_id(&parentID, self.pointer, "HEAD")
+			guard nameToIDResult == GIT_OK.rawValue else {
+				return .failure(NSError(gitError: nameToIDResult, pointOfFailure: "git_reference_name_to_id"))
+			}
+			return commit(OID(parentID)).flatMap { parentCommit in
+				commit(tree: treeOID, parents: [parentCommit], message: message, signature: signature)
+			}
+		}
+	}
+
 	// MARK: - Diffs
 
 	public func diff(for commit: Commit) -> Result<Diff, NSError> {