. "$BST_LIB"
require which which/present

# GNU which 2.21 (poky recipes-extended). Resolves a command name against PATH
# with bash's algorithm. busybox also ships a `which` applet, so the first job
# here is proving update-alternatives handed /usr/bin/which to the GNU one
# (priority 100) and not the applet (50) -- every switch below only exists in
# the GNU tool, and a busybox `which` would fail them all.

check_out which/version-gnu "GNU which v2.21" which --version
check    which/version-rc   which --version

w=$(command -v which)
check_eq which/self-path /usr/bin/which "$w"
check_out which/self "/usr/bin/which" which which

tmp=${TMPDIR:-/tmp}/bst-which.$$
mkdir -p "$tmp/a" "$tmp/b"
printf '#!/bin/sh\necho hi\n' > "$tmp/a/bsttool"; chmod +x "$tmp/a/bsttool"
cp "$tmp/a/bsttool" "$tmp/b/bsttool"
: > "$tmp/a/bstnonexec"                       # present but not executable

# --- PATH resolution ---------------------------------------------------------
out=$(PATH="$tmp/a:$PATH" which bsttool 2>&1)
check_eq which/resolve "$tmp/a/bsttool" "$out"
check_rc which/rc-found   0 env PATH="$tmp/a:$PATH" which bsttool
check_rc which/rc-missing 1 env PATH="$tmp/a:$PATH" which bstnosuchcmd

# the not-found diagnostic goes to stderr and names the command
out=$(PATH="$tmp/a:$PATH" which bstnosuchcmd 2>&1)
case "$out" in *"no bstnosuchcmd in"*) bst_ok which/missing-msg ;;
  *) bst_notok which/missing-msg "$(_bst_1line "$out")" ;; esac

# a file on PATH that is not executable is not a match -- the x-bit is the test,
# not mere presence
check_rc which/skip-nonexec 1 env PATH="$tmp/a:$PATH" which bstnonexec

# --- -a / --all --------------------------------------------------------------
# every match, in PATH order; the plain form stops at the first
n=$(PATH="$tmp/a:$tmp/b:$PATH" which -a bsttool 2>/dev/null | wc -l | tr -d ' ')
check_eq which/all-count 2 "$n"
first=$(PATH="$tmp/a:$tmp/b:$PATH" which -a bsttool 2>/dev/null | head -1)
check_eq which/all-order "$tmp/a/bsttool" "$first"
n1=$(PATH="$tmp/a:$tmp/b:$PATH" which bsttool 2>/dev/null | wc -l | tr -d ' ')
check_eq which/first-only 1 "$n1"
check_rc which/all-missing-rc 1 env PATH="$tmp/a:$PATH" which -a bstnosuchcmd

# --- argument handling -------------------------------------------------------
# an absolute path is reported as given
out=$(PATH="$tmp/a:$PATH" which "$tmp/a/bsttool" 2>&1)
check_eq which/abs-path "$tmp/a/bsttool" "$out"
# -- ends option parsing
out=$(PATH="$tmp/a:$PATH" which -- bsttool 2>&1)
check_eq which/dashdash "$tmp/a/bsttool" "$out"
# several commands: a missing one makes the status 1, the found one still prints
out=$(PATH="$tmp/a:$PATH" which bsttool bstnosuchcmd 2>&1); rc=$?
check_eq which/multi-rc 1 "$rc"
case "$out" in *"$tmp/a/bsttool"*) bst_ok which/multi-found ;;
  *) bst_notok which/multi-found "found command not printed: $(_bst_1line "$out")" ;; esac
check_rc which/multi-all-found 0 env PATH="$tmp/a:$PATH" which bsttool bsttool

# --- PATH-hygiene switches (the ones busybox has no answer for) --------------
# a relative "." entry: --show-dot reports it as ./, --skip-dot ignores it
( cd "$tmp" && out=$(PATH="./a:$PATH" which --show-dot bsttool 2>&1)
  case "$out" in ./a/bsttool) bst_ok which/show-dot ;;
    *) bst_notok which/show-dot "want './a/bsttool' got '$(_bst_1line "$out")'" ;; esac )
( cd "$tmp" && out=$(PATH="./a:$tmp/b:$PATH" which --skip-dot bsttool 2>&1)
  check_eq which/skip-dot "$tmp/b/bsttool" "$out" )

# --show-tilde abbreviates $HOME; run with HOME set to the scratch dir so the
# assertion does not depend on the image's real home. Upstream disables the
# switch for the superuser -- which.1: "This option is ignored when which is
# invoked as root", which.c: show_tilde = (!tty_only && geteuid() != superuser)
# -- and this image's shell is root, so there the full path IS the pass.
out=$(HOME="$tmp" PATH="$tmp/a:$PATH" which --show-tilde bsttool 2>&1)
if [ "$(id -u 2>/dev/null || echo 0)" = 0 ]; then
  check_eq which/show-tilde "$tmp/a/bsttool" "$out"
else
  check_eq which/show-tilde "~/a/bsttool" "$out"
fi

# --tty-only stops processing the options to its right when stdout is not a tty;
# the command itself still resolves, which is the property that matters here
out=$(PATH="$tmp/a:$PATH" which --tty-only bsttool 2>&1)
check_eq which/tty-only "$tmp/a/bsttool" "$out"

# --- shell-table integration -------------------------------------------------
# --read-alias/--read-functions consume a shell's tables on stdin. The login
# shell here is busybox sh, which exports neither, so which only ever sees what
# a caller pipes in -- upstream's documented limitation. Feed it explicitly.
out=$(printf "alias bstll='ls -l'\n" | which --read-alias bstll 2>&1)
case "$out" in *"alias bstll="*) bst_ok which/read-alias ;;
  *) bst_notok which/read-alias "$(_bst_1line "$out")" ;; esac
# --skip-alias ignores the piped table and falls back to PATH
out=$(printf "alias bsttool='no-such'\n" | PATH="$tmp/a:$PATH" which --skip-alias bsttool 2>&1)
check_eq which/skip-alias "$tmp/a/bsttool" "$out"

# --- diagnostics -------------------------------------------------------------
# An unknown option and a bare invocation both print usage and exit non-zero.
# 2.21 and 2.25 both use 255, but only "non-zero + a diagnostic" is asserted so
# a later version bump cannot turn a working tool red.
out=$(which --bst-bogus-option 2>&1); rc=$?
if [ "$rc" -ne 0 ]; then bst_ok which/badopt-rc
else bst_notok which/badopt-rc "accepted an unknown option (rc=0)"; fi
case "$out" in *"unrecognized option"*) bst_ok which/badopt-msg ;;
  *) bst_notok which/badopt-msg "$(_bst_1line "$out")" ;; esac
out=$(which 2>&1); rc=$?
if [ "$rc" -ne 0 ]; then bst_ok which/noargs-rc
else bst_notok which/noargs-rc "accepted no arguments (rc=0)"; fi
case "$out" in *Usage:*) bst_ok which/noargs-usage ;;
  *) bst_notok which/noargs-usage "$(_bst_1line "$out")" ;; esac

rm -rf "$tmp"