#!/bin/sh
OCI_ENTRYPOINT=''
OCI_CMD='"/bin/bash"'

# When SINGULARITY_NO_EVAL set, use OCI compatible behavior that does
# not evaluate resolved CMD / ENTRYPOINT / ARGS through the shell, and
# does not modify expected quoting behavior of args.
if [ -n "$SINGULARITY_NO_EVAL" ]; then
    # ENTRYPOINT only - run entrypoint plus args
    if [ -z "$OCI_CMD" ] && [ -n "$OCI_ENTRYPOINT" ]; then
        
        exec "$@"
    fi

    # CMD only - run CMD or override with args
    if [ -n "$OCI_CMD" ] && [ -z "$OCI_ENTRYPOINT" ]; then
        if [ $# -eq 0 ]; then
            set -- '/bin/bash' "$@"

        fi
        exec "$@"
    fi

    # ENTRYPOINT and CMD - run ENTRYPOINT with CMD as default args
    # override with user provided args
    if [ $# -eq 0 ]; then
        set -- '/bin/bash' "$@"

    fi
    exec "$@"
fi

# Standard Apptainer behavior evaluates CMD / ENTRYPOINT / ARGS
# combination through shell before exec, and requires special quoting
# due to concatenation of CMDLINE_ARGS.
CMDLINE_ARGS=""
# prepare command line arguments for evaluation
for arg in "$@"; do
        CMDLINE_ARGS="${CMDLINE_ARGS} \"$arg\""
done

# ENTRYPOINT only - run entrypoint plus args
if [ -z "$OCI_CMD" ] && [ -n "$OCI_ENTRYPOINT" ]; then
    if [ $# -gt 0 ]; then
        SINGULARITY_OCI_RUN="${OCI_ENTRYPOINT} ${CMDLINE_ARGS}"
    else
        SINGULARITY_OCI_RUN="${OCI_ENTRYPOINT}"
    fi
fi

# CMD only - run CMD or override with args
if [ -n "$OCI_CMD" ] && [ -z "$OCI_ENTRYPOINT" ]; then
    if [ $# -gt 0 ]; then
        SINGULARITY_OCI_RUN="${CMDLINE_ARGS}"
    else
        SINGULARITY_OCI_RUN="${OCI_CMD}"
    fi
fi

# ENTRYPOINT and CMD - run ENTRYPOINT with CMD as default args
# override with user provided args
if [ $# -gt 0 ]; then
    SINGULARITY_OCI_RUN="${OCI_ENTRYPOINT} ${CMDLINE_ARGS}"
else
    SINGULARITY_OCI_RUN="${OCI_ENTRYPOINT} ${OCI_CMD}"
fi

# Evaluate shell expressions first and set arguments accordingly,
# then execute final command as first container process
eval "set ${SINGULARITY_OCI_RUN}"
exec "$@"