git-arc: Add -c flag to patch to commit the change

git arc patch -c D1234 will download differential D1234, try to apply it
to the tree, and if successful will ask phab for the title and
summary. It will construct a commit message with that, the reviewers,
and the differential revision. It also tries its best to deduce the
proper 'author' to use for the commit, and warn if it thinks it has made
a bad choice.

Sponsored by:		Netflix
Reviewed by:		markj
Differential Revision:	https://reviews.freebsd.org/D39992

tools/tools/git/git-arc.1

@@ -41,7 +41,9 @@
 .Nm
 .Cm list Ar commit ... Ns | Ns Ar commit-range
 .Nm
-.Cm patch Ar diff1 Ns Op Cm \&, Ns Ar diff2
+.Cm patch
+.Op Fl c
+.Ar diff1 Ns Op Cm \&, Ns Ar diff2
 .Nm
 .Cm stage
 .Op Fl b Ar branch
@@ -211,6 +213,15 @@ and stage it:
 $ git arc patch D12345
 .Ed
 .Pp
+Apply the patch in review D23456 to the currently checked-out tree,
+and commit it to the tree with the commit message in the review and
+make the best guess for what to use for author.
+If the guess is considered unreliable, the user is prompted to see
+if they wish to use it (or abort).
+.Bd -literal -offset indent
+$ git arc patch -c D23456
+.Ed
+.Pp
 List the status of reviews for all the commits in the branch
 .Dq feature :
 .Bd -literal -offset indent

tools/tools/git/git-arc.sh

@@ -51,7 +51,7 @@ Usage: git arc [-vy] <command> <arguments>
 Commands:
   create [-l] [-r <reviewer1>[,<reviewer2>...]] [-s subscriber[,...]] [<commit>|<commit range>]
   list <commit>|<commit range>
-  patch <diff1> [<diff2> ...]
+  patch [-c] <diff1> [<diff2> ...]
   stage [-b branch] [<commit>|<commit range>]
   update [-m message] [<commit>|<commit range>]
 
@@ -133,6 +133,11 @@ Examples:
 
   $ git arc patch D12345
 
+  Apply the patch in review D12345 to the currently checked-out tree, and
+  commit it using the review's title, summary and author.
+
+  $ git arc patch -c D12345
+
   List the status of reviews for all the commits in the branch "feature":
 
   $ git arc list main..feature
@@ -455,18 +460,162 @@ gitarc__list()
     done
 }
 
+# Try to guess our way to a good author name. The DWIM is strong in this
+# function, but these heuristics seem to generally produce the right results, in
+# the sample of src commits I checked out.
+find_author()
+{
+    local addr name email author_addr author_name
+
+    addr="$1"
+    name="$2"
+    author_addr="$3"
+    author_name="$4"
+
+    # The Phabricator interface doesn't have a simple way to get author name and
+    # address, so we have to try a number of heuristics to get the right result.
+
+    # Choice 1: It's a FreeBSD committer. These folks have no '.' in their phab
+    # username/addr. Sampled data in phab suggests that there's a high rate of
+    # these people having their local config pointing at something other than
+    # freebsd.org (which isn't surprising for ports committers getting src
+    # commits reviewed).
+    case "${addr}" in
+    *.*) ;;		# external user
+    *)
+	echo "${name} <${addr}@FreeBSD.org>"
+	return
+	;;
+    esac
+
+    # Choice 2: author_addr and author_name were set in the bundle, so use
+    # that. We may need to filter some known bogus ones, should they crop up.
+    if [ -n "$author_name" -a -n "$author_addr" ]; then
+	echo "${author_name} <${author_addr}>"
+	return
+    fi
+
+    # Choice 3: We can find this user in the FreeBSD repo. They've submited
+    # something before, and they happened to use an email that's somewhat
+    # similar to their phab username.
+    email=$(git log -1 --author "$(echo ${addr} | tr _ .)" --pretty="%aN <%aE>")
+    if [ -n "${email}" ]; then
+	echo "${email}"
+	return
+    fi
+
+    # Choice 4: We know this user. They've committed before, and they happened
+    # to use the same name, unless the name has the word 'user' in it. This
+    # might not be a good idea, since names can be somewhat common (there
+    # are two Andrew Turners that have contributed to FreeBSD, for example).
+    if ! (echo "${name}" | grep -w "[Uu]ser" -q); then
+	email=$(git log -1 --author "${name}" --pretty="%aN <%aE>")
+	if [ -n "$email" ]; then
+	    echo "$email"
+	    return
+	fi
+    fi
+
+    # Choice 5: Wing it as best we can. In this scenario, we replace the last _
+    # with a @, and call it the email address...
+    # Annoying fun fact: Phab replaces all non alpha-numerics with _, so we
+    # don't know if the prior _ are _ or + or any number of other characters.
+    # Since there's issues here, prompt
+    a=$(printf "%s <%s>\n" "${name}" $(echo "$addr" | sed -e 's/\(.*\)_/\1@/'))
+    echo "Making best guess: Truning ${addr} to ${a}"
+    if ! prompt; then
+       echo "ABORT"
+       return
+    fi
+    echo "${a}"
+}
+
+patch_commit()
+{
+    local diff reviewid review_data authorid user_data user_addr user_name author
+    local tmp author_addr author_name
+
+    diff=$1
+    reviewid=$(diff2phid "$diff")
+    # Get the author phid for this patch
+    review_data=$(echo '{
+                  "constraints": {"phids": ["'"$reviewid"'"]}
+		}' |
+        arc_call_conduit -- differential.revision.search)
+    authorid=$(echo "$review_data" | jq -r '.response.data[].fields.authorPHID' )
+    # Get metadata about the user that submitted this patch
+    user_data=$(echo '{
+                  "constraints": {"phids": ["'"$authorid"'"]}
+		}' |
+            arc call-conduit -- user.search | grep -v ^Warning: |
+            jq -r '.response.data[].fields')
+    user_addr=$(echo "$user_data" | jq -r '.username')
+    user_name=$(echo "$user_data" | jq -r '.realName')
+    # Dig the data out of querydiffs api endpoint, although it's deprecated,
+    # since it's one of the few places we can get email addresses. It's unclear
+    # if we can expect multiple difference ones of these. Some records don't
+    # have this data, so we remove all the 'null's. We sort the results and
+    # remove duplicates 'just to be sure' since we've not seen multiple
+    # records that match.
+    diff_data=$(echo '{
+		"revisionIDs": [ '"${diff#D}"' ]
+		}' | arc_call_conduit -- differential.querydiffs |
+	     jq -r '.response | flatten | .[]')
+    author_addr=$(echo "$diff_data" | jq -r ".authorEmail?" | sort -u)
+    author_name=$(echo "$diff_data" | jq -r ".authorName?" | sort -u)
+    author=$(find_author "$user_addr" "$user_name" "$author_addr" "$author_name")
+
+    # If we had to guess, and the user didn't want to guess, abort
+    if [ "${author}" = "ABORT" ]; then
+	warn "Not committing due to uncertainty over author name"
+	exit 1
+    fi
+
+    tmp=$(mktemp)
+    echo "$review_data" | jq -r '.response.data[].fields.title' > $tmp
+    echo >> $tmp
+    echo "$review_data" | jq -r '.response.data[].fields.summary' >> $tmp
+    echo >> $tmp
+    # XXX this leaves an extra newline in some cases.
+    reviewers=$(diff2reviewers "$diff" | sed '/^$/d' | paste -sd ',' - | sed 's/,/, /g')
+    if [ -n "$reviewers" ]; then
+        printf "Reviewed by:\t%s\n" "${reviewers}" >> "$tmp"
+    fi
+    # XXX TODO refactor with gitarc__stage maybe?
+    printf "Differential Revision:\thttps://reviews.freebsd.org/%s\n" "${diff}" >> "$tmp"
+    git commit --author "${author}" --file "$tmp"
+    rm "$tmp"
+}
+
 gitarc__patch()
 {
-    local rev
+    local rev commit
 
     if [ $# -eq 0 ]; then
         err_usage
     fi
 
+    commit=false
+    while getopts c o; do
+        case "$o" in
+        c)
+	    require_clean_work_tree "patch -c"
+            commit=true
+            ;;
+        *)
+            err_usage
+            ;;
+        esac
+    done
+    shift $((OPTIND-1))
+
     for rev in "$@"; do
         arc patch --skip-dependencies --nocommit --nobranch --force "$rev"
         echo "Applying ${rev}..."
         [ $? -eq 0 ] || break
+	if ${commit}; then
+	    patch_commit $rev
+	fi
     done
 }