#!/bin/bash

srcdir=$1
outdir=$2
# 1 when the library was configured with a threading backend, 0 for
# -DAKERR_THREADS=none. Stamped into the header so a consumer cannot disagree
# with the library about whether it locks and whether its per-thread state is
# thread local. Defaults to 1 for a hand-run of this script.
thread_safe=${3:-1}
# 1 for a normal (libc-linked) build, 0 for -DAKERR_USE_STDLIB=OFF. The
# freestanding build cannot shell out to `errno --list` (moreutils) or
# #include <errno.h>, so it skips the errno scrape entirely and stamps
# AKERR_LAST_ERRNO_VALUE from a fixed fallback instead. Defaults to 1 for a
# hand-run of this script.
use_stdlib=${4:-1}
# AKERR_LAST_ERRNO_VALUE to stamp when use_stdlib is 0. Defaults to 133
# (Linux's EHWPOISON) so the reserved band assertion in akerror.tmpl.h still
# holds.
last_errno_fallback=${5:-133}
# Bytes reserved for the fname/function fields of akerr_ErrorContext. Defaults
# to 4096 (PATH_MAX on Linux/glibc) so sizeof(akerr_ErrorContext) and the
# soname stay unchanged from before this became a build option.
max_error_fname_length=${6:-4096}

if [ "${thread_safe}" != "0" ] && [ "${thread_safe}" != "1" ]; then
    echo "$0: thread-safe argument must be 0 or 1, got '${thread_safe}'" >&2
    exit 1
fi

if [ "${use_stdlib}" != "0" ] && [ "${use_stdlib}" != "1" ]; then
    echo "$0: use-stdlib argument must be 0 or 1, got '${use_stdlib}'" >&2
    exit 1
fi

mkdir -p ${outdir}/src
mkdir -p ${outdir}/include
rm -f ${outdir}/src/errno.c

if [ "${use_stdlib}" = "1" ]; then
    echo "#include <akerror.h>" >> ${outdir}/src/errno.c
    echo "#include <errno.h>" >> ${outdir}/src/errno.c
    cat >> ${outdir}/src/errno.c <<'EOF'

/*
 * These names belong to the library's own reserved band, and this runs from
 * akerr_init(), which has no caller to raise into -- so it goes through
 * __akerr_name_library_status(), which reports a refusal and terminates rather
 * than leaving every later stack trace to print "Unknown Error" for an errno.
 * Keeping the branch in src/error.c also keeps this generated file free of
 * control flow no test can reach.
 */
EOF
    echo "void akerr_init_errno(void) {" >> ${outdir}/src/errno.c
    maxval=$(errno --list | cut -d ' ' -f 2 | sort -g | tail -n 1)
    errno --list | while read LINE; do
        define=$(echo "$LINE" | cut -d ' ' -f 1);
        value=$(echo "$LINE" | cut -d ' ' -f 2);
        desc=$(echo "$LINE" | cut -d ' ' -f 3-);
        echo "	__akerr_name_library_status(${define}, \"${desc}\");" >> ${outdir}/src/errno.c ;
    done;
    echo "}" >> ${outdir}/src/errno.c
else
    # Freestanding: no `errno --list` shellout (requires moreutils and
    # <errno.h>, neither freestanding-safe), and no errno.c at all -- CMake
    # does not compile it into the library under AKERR_USE_STDLIB=OFF. Still
    # write a stub so the OUTPUT this rule promises always exists.
    echo "/* AKERR_USE_STDLIB=OFF: no errno table generated. */" >> ${outdir}/src/errno.c
    maxval=${last_errno_fallback}
fi

sed -e "s/#define AKERR_LAST_ERRNO_VALUE .*/#define AKERR_LAST_ERRNO_VALUE      ${maxval}/" \
    -e "s/#define AKERR_THREAD_SAFE .*/#define AKERR_THREAD_SAFE           ${thread_safe}/" \
    -e "s/#define AKERR_MAX_ERROR_FNAME_LENGTH .*/#define AKERR_MAX_ERROR_FNAME_LENGTH                       ${max_error_fname_length}/" \
    ${srcdir}/include/akerror.tmpl.h > ${outdir}/include/akerror.h