brancher: pre-generate deltas when creating a branch

Instead of having to fetch the branches locally and manually
run cidiff just generate the output after creating each branch.
We can make UI link to it later.

Signed-off-by: Jakub Kicinski <[email protected]>

contest/cidiff

@@ -15,6 +15,15 @@ if [ x$BRANCH1$BRANCH2 == x ]; then
     BRANCH1=${branches[0]}
     BRANCH2=${branches[1]}
 
+    echo "  " $BRANCH1
+    echo "  " $BRANCH2
+    echo
+elif [ x$BRANCH2 == x ]; then
+    echo "Single branch specified, using that and the previous one:"
+    branches=( $(git branch -a | grep -B1 "$1") )
+    BRANCH1=${branches[0]}
+    BRANCH2=${branches[1]}
+
     echo "  " $BRANCH1
     echo "  " $BRANCH2
     echo

pw_brancher.py

@@ -6,6 +6,7 @@
 import json
 import os
 import psycopg2
+import subprocess
 import time
 from typing import List, Tuple
 import uuid
@@ -32,6 +33,7 @@
 [output]
 branches=branches.json
 info=branches-info.json
+deltas=/path/to/dir/
 [db]
 db=db-name
 """
@@ -190,6 +192,18 @@ def db_insert(config, state, name):
         cur.execute("INSERT INTO branches VALUES " + arg.decode('utf-8'))
 
 
+def generate_deltas(config, name):
+    outdir = config.get("output", "deltas", fallback=None)
+    if not outdir:
+        return
+
+    outfile = os.path.join(outdir, name)
+    cidiff = os.path.join(__file__, "contest", "cidiff")
+
+    with open(outfile, 'w') as fp:
+        subprocess.run([cidiff, name], stdout=fp, check=True)
+
+
 def create_new(pw, config, state, tree, tgt_remote) -> None:
     now = datetime.datetime.now(datetime.UTC)
     pfx = config.get("target", "branch_pfx")
@@ -235,6 +249,10 @@ def create_new(pw, config, state, tree, tgt_remote) -> None:
     tree.git_push(tgt_remote, "HEAD:" + branch_name)
     log_end_sec()
 
+    log_open_sec("Generate deltas")
+    generate_deltas(config, branch_name)
+    log_end_sec()
+
 
 def state_delete_branch(state, br):
     del state["branches"][br]