From 31cb850c04873e29ad1ff5a5d5255283827907b2 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 27 Sep 2016 06:42:36 +0200
Subject: Implement update script

---
 update | 164 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100755 update

(limited to 'update')

diff --git a/update b/update
new file mode 100755
index 0000000..fc2ba54
--- /dev/null
+++ b/update
@@ -0,0 +1,164 @@
+#! /usr/bin/env bash
+
+# Commit and push an update to an existing note.
+#
+# -c
+#   Commit only, don't push.
+#
+usage="usage: $0 [-c]"
+
+owd=`pwd`
+trap "{ cd $owd; exit 1; }" ERR
+set -o errtrace # Trap in functions.
+
+function info () { echo "$*" 1>&2; }
+function error () { info "$*"; exit 1; }
+
+push="y"
+
+while [ $# -gt 0 ]; do
+  case $1 in
+    -c)
+      push="n"
+      shift
+      ;;
+    *)
+      error "$usage"
+      ;;
+  esac
+done
+
+if git status --porcelain | grep -q '^M '; then
+  error "error: repository already has staged changes"
+fi
+
+# @@ We could probably handle the case where extra files are added to the
+# note. We just need to make sure they are not changes to other notes.
+#
+if git status --porcelain | grep -q '^?? '; then
+  error "error: repository has untracked files"
+fi
+
+modified="$(git status --porcelain  | sed -n -e 's/^ M \(.*\)/\1/p')"
+
+mc="$(echo "$modified" | wc -w)"
+
+if [ "$mc" -eq 0 ]; then
+  error "error: nothing modified"
+fi
+
+if [ "$mc" -gt 1 ]; then
+  error "error: multiple modified files"
+fi
+
+# Extract the start line and count from the changeset header.
+#
+# The format is:
+#
+# @@ [+-]FROM-START,FROM-COUNT [+-]TO-START,TO-COUNT @@
+#
+# Note that if the changeset has only one line then the count is omitted.
+#
+function changeset_start ()
+{
+  echo "$1" | sed -e 's/^@@ [^ ]* [+-]\([^, ]*\).*$/\1/'
+}
+
+function changeset_count ()
+{
+  local r
+  r="$(echo "$1" | sed -n -e 's/^@@ [^ ]* [+-][^,]*,\([^ ]*\) @@$/\1/p')"
+  if [ -z "$r" ]; then
+    r="1"
+  fi
+  echo "$r"
+}
+
+#changeset_start "@@ -12,3 +13,11 @@"
+#changeset_count "@@ -12,3 +13,11 @@"
+#changeset_start "@@ -12 +13 @@"
+#changeset_count "@@ -12 +13 @@"
+
+h=
+if [ "$(basename "$modified")" = "list" ]; then
+  #
+  # This is a list of notes. The plan is to get the start line numbers for the
+  # first and last change set. We then scan the list line by line looking for
+  # headers until we hit the start of the first change set: the last header
+  # that we see should be our header. We also continue scanning until we hit
+  # the end of the last changeset: if we see any headers then we are updating
+  # multiple notes.
+  #
+
+  # Get the diff output as a list of change set headers.
+  #
+  diff="$(git diff -U0 | sed -n -e '/^@@ /p')"
+
+  fc="$(echo "$diff" | head -n 1)"
+  lc="$(echo "$diff" | tail -n 1)"
+
+  sl="$(changeset_start "$fc")"
+  el="$(($(changeset_start "$lc") + $(changeset_count "$lc") - 1))"
+
+  # Scan the list looking for headers.
+  #
+  l=
+  c="0"
+  while read l || [ -n "$l" ]; do
+
+    # Stop if we are past the end line.
+    #
+    c="$(($c + 1))"
+    if [ "$c" -gt "$el" ]; then
+      break
+    fi
+
+    # See if this is a header.
+    #
+    if echo "$l" | grep -q '^[-?!] '; then
+
+      # If we are past the start line then we are modifying multiple notes.
+      #
+      if [ "$c" -gt "$sl" ]; then
+	error "error: multiple modified notes in $modified:${sl}-${el}"
+      fi
+
+      # This is the last header.
+      #
+      h="$l"
+    fi
+  done < <(cat "$modified")
+
+  if [ -z "$h" ]; then
+    error "error: unable to find note header for $modified:${sl}-${el}"
+  fi
+else
+  # This is a file note. All we need to do is get its header (the first line).
+  #
+  h="$(head -n 1 "$modified")"
+fi
+
+# Header should start with one of [-?!].
+#
+sum="$(echo "$h" | sed -n -re 's/^[-?!] ([^[]*)( \[.*\])?$/\1/p')"
+
+if [ -z "$sum" ]; then
+  error "error: unable to parse note header '$h'"
+fi
+
+# By convention the first label is a note type (bug, feature, etc).
+#
+type="$(echo "$h" | sed -n -re 's/^[^[]*\[([^ ]*).*\]$/\1/p')"
+
+if [ -z "$type" ]; then
+  error "error: note header does not include note type as first label"
+fi
+
+# Ok, all looks good so add, commit and push the change.
+#
+git add "$modified"
+git ci -m "Update $type: $sum"
+
+if [ "$push" = "y" ]; then
+  git push
+fi
-- 
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