. "$BST_LIB"
# busybox ships no diffstat applet and there is no other diffstat on the image,
# so a bare `diffstat` already is this port — no update-alternatives name to
# disambiguate (unlike diff/patch/tar).
require diffstat diffstat/present

tmp=${TMPDIR:-/tmp}/bst-diffstat.$$

# A fixed unified diff — one file, 2 insertions, 1 deletion — so every expected
# count below is a property of diffstat's parse, not of whichever diff produced
# the input. Real diff output is covered separately at the end of this file.
cat > "$tmp.one" <<'EOF' 2>/dev/null
--- a/hello.c
+++ b/hello.c
@@ -1,3 +1,4 @@
 line one
-line two
+line 2
 line three
+line four
EOF

# two files in one diff, 3 insertions / 2 deletions overall
cat > "$tmp.two" <<'EOF' 2>/dev/null
--- a/hello.c
+++ b/hello.c
@@ -1,3 +1,4 @@
 line one
-line two
+line 2
 line three
+line four
--- a/README
+++ b/README
@@ -1,2 +1,2 @@
 title
-old body
+new body
EOF

check_out diffstat/version     "diffstat version 1.66"  diffstat -V

# default report: the filename column, the scaled +/- histogram (3 changed
# lines -> "++-"), and the git-style summary line.
check_out diffstat/file-name   "hello.c |"              diffstat "$tmp.one"
check_out diffstat/histogram   "3 ++-"                  diffstat "$tmp.one"
check_out diffstat/summary     "1 file changed, 2 insertions(+), 1 deletion(-)" \
                                                        diffstat "$tmp.one"
# with no filename argument diffstat reads the diff from stdin
check_out diffstat/stdin       "1 file changed"          sh -c "diffstat < '$tmp.one'"

# -t emits the counts as CSV: the header, then inserted,deleted,modified,name.
check_out diffstat/csv-header  "INSERTED,DELETED,MODIFIED,FILENAME"  diffstat -t "$tmp.one"
check_out diffstat/csv-counts  '2,1,0,"hello.c"'                     diffstat -t "$tmp.one"

# -l lists the affected filenames only, with no histogram or summary at all.
check_eq  diffstat/list-only   "hello.c"  "$(diffstat -l "$tmp.one" 2>&1)"

# -m folds a matched insert/delete pair into one modification, so the same diff
# reports 1 insertion + 1 modification instead of 2 insertions + 1 deletion.
check_out diffstat/merged      "1 insertion(+), 1 modification(!)"   diffstat -m "$tmp.one"

# a multi-file diff: both files are listed and the summary pluralises + totals.
check_out diffstat/two-names   "README"    diffstat "$tmp.two"
check_out diffstat/two-summary "2 files changed, 3 insertions(+), 2 deletions(-)" \
                                                        diffstat "$tmp.two"

# an empty diff is not an error: diffstat says so and exits 0, and -q silences it.
check_out diffstat/empty       "0 files changed"  sh -c ": | diffstat"
check_eq  diffstat/quiet       ""                 "$(: | diffstat -q 2>&1)"

# end to end on output a diff actually produced: busybox diff is always present
# and its -u format is the same unified format. One changed line -> 1 insertion
# and 1 deletion. diff exits 1 when files differ, so normalise that.
printf 'alpha\nbeta\ngamma\n' > "$tmp.a" 2>/dev/null
printf 'alpha\nBETA\ngamma\n' > "$tmp.b" 2>/dev/null
busybox diff -u "$tmp.a" "$tmp.b" > "$tmp.d" 2>/dev/null; true
check_out diffstat/real-diff   "1 file changed, 1 insertion(+), 1 deletion(-)" \
                                                        diffstat "$tmp.d"

rm -f "$tmp.one" "$tmp.two" "$tmp.a" "$tmp.b" "$tmp.d"