#!/bin/sh
# From Gerrit Code Review 2.12.7
#
# Part of Gerrit Code Review (https://www.gerritcodereview.com/)
#
# Copyright (C) 2009 The Android Open Source Project
#
# SPDX-License-Identifier: Apache-2.0
#

unset GREP_OPTIONS

CHANGE_ID_AFTER="Bug|Issue|Test"
MSG="$1"

# Check for, and add if missing, a unique Change-Id
#
add_ChangeId() {
	clean_message=`sed -e '
		/^diff --git .*/{
			s///
			q
		}
		/^Signed-off-by:/d
		/^#/d
	' "$MSG" | git stripspace`
	if test -z "$clean_message"
	then
		return
	fi

	# Do not add Change-Id to temp commits
	if echo "$clean_message" | head -1 | grep -q '^\(fixup\|squash\)!'
	then
		return
	fi

	if test "false" = "`git config --bool --get gerrit.createChangeId`"
	then
		return
	fi

	# Do not add Change-Id on packaging branches
	if git branch | grep -q '^\* \(debian\|ubuntu\)/'
	then
		return
	fi

	# Does Change-Id: already exist? if so, exit (no change).
	if grep -i '^Change-Id:' "$MSG" >/dev/null
	then
		return
	fi

	id=`_gen_ChangeId`
	T="$MSG.tmp.$$"
	AWK=awk
	if [ -x /usr/xpg4/bin/awk ]; then
		# Solaris AWK is just too broken
		AWK=/usr/xpg4/bin/awk
	fi

	# Get core.commentChar from git config or use default symbol
	commentChar=`git config --get core.commentChar`
	commentChar=${commentChar:-#}

	# How this works:
	# - parse the commit message as (textLine+ blankLine*)*
	# - assume textLine+ to be a footer until proven otherwise
	# - exception: the first block is not footer (as it is the title)
	# - read textLine+ into a variable
	# - then count blankLines
	# - once the next textLine appears, print textLine+ blankLine* as these
	#   aren't footer
	# - in END, the last textLine+ block is available for footer parsing
	$AWK '
	BEGIN {
		# while we start with the assumption that textLine+
		# is a footer, the first block is not.
		isFooter = 0
		footerComment = 0
		blankLines = 0
	}

	# Skip lines starting with commentChar without any spaces before it.
	/^'"$commentChar"'/ { next }

	# Skip the line starting with the diff command and everything after it,
	# up to the end of the file, assuming it is only patch data.
	# If more than one line before the diff was empty, strip all but one.
	/^diff --git / {
		blankLines = 0
		while (getline) { }
		next
	}

	# Count blank lines outside footer comments
	/^$/ && (footerComment == 0) {
		blankLines++
		next
	}

	# Catch footer comment
	/^\[[a-zA-Z0-9-]+:/ && (isFooter == 1) {
		footerComment = 1
	}

	/]$/ && (footerComment == 1) {
		footerComment = 2
	}

	# We have a non-blank line after blank lines. Handle this.
	(blankLines > 0) {
		print lines
		for (i = 0; i < blankLines; i++) {
			print ""
		}

		lines = ""
		blankLines = 0
		isFooter = 1
		footerComment = 0
	}

	# Detect that the current block is not the footer
	(footerComment == 0) && (!/^\[?[a-zA-Z0-9-]+:/ || /^[a-zA-Z0-9-]+:\/\//) {
		isFooter = 0
	}

	{
		# We need this information about the current last comment line
		if (footerComment == 2) {
			footerComment = 0
		}
		if (lines != "") {
			lines = lines "\n";
		}
		lines = lines $0
	}

	# Footer handling:
	# If the last block is considered a footer, splice in the Change-Id at the
	# right place.
	# Look for the right place to inject Change-Id by considering
	# CHANGE_ID_AFTER. Keys listed in it (case insensitive) come first,
	# then Change-Id, then everything else (eg. Signed-off-by:).
	#
	# Otherwise just print the last block, a new line and the Change-Id as a
	# block of its own.
	END {
		unprinted = 1
		if (isFooter == 0) {
			print lines "\n"
			lines = ""
		}
		changeIdAfter = "^(" tolower("'"$CHANGE_ID_AFTER"'") "):"
		numlines = split(lines, footer, "\n")
		for (line = 1; line <= numlines; line++) {
			if (unprinted && match(tolower(footer[line]), changeIdAfter) != 1) {
				unprinted = 0
				print "Change-Id: I'"$id"'"
			}
			print footer[line]
		}
		if (unprinted) {
			print "Change-Id: I'"$id"'"
		}
	}' "$MSG" > "$T" && mv "$T" "$MSG" || rm -f "$T"
}
_gen_ChangeIdInput() {
	echo "tree `git write-tree`"
	if parent=`git rev-parse "HEAD^0" 2>/dev/null`
	then
		echo "parent $parent"
	fi
	echo "author `git var GIT_AUTHOR_IDENT`"
	echo "committer `git var GIT_COMMITTER_IDENT`"
	echo
	printf '%s' "$clean_message"
}
_gen_ChangeId() {
	_gen_ChangeIdInput |
	git hash-object -t commit --stdin
}

reject_long_message() {
	read -r firstline < "$MSG"
	if [ ${#firstline} -gt 80 ]
	then
		printf "\n\nERROR: First line in the commit message must not exceed 80 characters\n\n"
		exit 1
	fi
}

# Remove trailing spaces, fix blank lines, fix capitalization of "Bug" tags.
fixup_message() {
	# Remove trailing tabs and spaces
	tab=$(printf '\t')
	msg="$(sed -e "s/[${tab} ]*$//" "$MSG")"

	# Ensures proper positioning of "Ping-Bug" or "Bug" tags:
	# - Must be preceded by one blank line.
	# - Must not be succeeded by a blank line.
	# - Must not mistake "bug:" in the description for tags in contexts such
	#   as "to reproduce this\nbug: 1) step 2) another step 3) etc.".
	# - If preceded by other tags (like Change-Id), do not add newline.
	msg=$(echo "$msg" | awk '
	# Eat the "--verbose" diff
	/^#.*(8<|>8)/ {
		while (getline) { }
		next
	}
	# Ignore other comments
	/^#/ {
		next
	}

	# Find "Bug" lines that potentially need to be fixed up. Assume that
	# relevant bug numbers are at least four digits.
	{
		if (match(tolower($0), /^(ping-)?bug: *[0-9][0-9][0-9][0-9]/)) {
			if (buffer == "") {
				needsnewline = !lastblank && !potentialTag;
				buffer = $0
			} else {
				buffer = buffer "\n" $0
			}
			next
		}
	}

	# Buffer tags and other blank lines when a fixup is potentially needed.
	{ potentialTag = 0 }
	/^[a-zA-Z0-9-]+:/ || /^$/ {
		potentialTag = 1
		if (buffer != "") {
			buffer = buffer "\n" $0;
			next
		}
	}

	# If some other text was found, assume it was not part of the footer.
	# Flush any buffer, unmodified.
	{
		if (buffer != "") {
			print buffer;
			buffer = ""
		}
		print;
		# Remember whether the last line was blank.
		lastblank = $0 == ""
	}

	END {
		# If any tags block is still open, fix up and print it.
		if (buffer != "") {
			if (needsnewline) {
				print ""
			}
			numlines = split(buffer, lines, "\n")
			for (line = 1; line <= numlines; line++) {
				s = lines[line];
				if (s != "") {
					# Fix capitalization
					sub(/^[Bb][Uu][Gg]/, "Bug", s);
					sub(/^[Pp][Ii][Nn][Gg]-[Bb][Uu][Gg]/, "Ping-Bug", s);
					# ensure single space after colon
					sub(/: */, ": ", s);
					print s;
				}
			}
		}
	}
	') && echo "$msg" > "$MSG"
}


add_ChangeId
reject_long_message
fixup_message