#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
#
# Copy firmware files based on WHENCE list
#

verbose=:
compress=cat
compext=
destdir=
num_jobs=1

usage() {
    echo "Usage: $0 [-v] [-jN] [--xz|--zstd] <destination directory>"
}

err() {
    printf "ERROR: %s\n" "$*"
    usage
    exit 1
}

warn() {
    printf "WARNING: %s\n" "$*"
}

has_gnu_parallel() {
    command -v parallel > /dev/null || return 1
    # moreutils parallel doesn't support --version; if it fails, not GNU
    parallel --version > /dev/null 2>&1 || return 1
    # Use tolower() instead of IGNORECASE (gawk-only extension)
    parallel --version 2>/dev/null \
        | awk '{if(tolower($0)~/gnu parallel/)found=1} END{exit !found}'
}

while test $# -gt 0; do
    case $1 in
        -v | --verbose)
            verbose=echo
            shift
            ;;

        -j*)
            num_jobs=$(echo "$1" | sed 's/-j//')
            num_jobs=${num_jobs:-1}
            if [ "$num_jobs" -gt 1 ] && ! has_gnu_parallel; then
                err "the GNU parallel command is required to use -j"
            fi
            parallel_args_file=$(mktemp)
            trap 'rm -f $parallel_args_file' EXIT INT QUIT TERM
            shift
            ;;

        --xz)
            if test "$compext" = ".zst"; then
                err "cannot mix XZ and ZSTD compression"
            fi
            compress="xz --compress --quiet --stdout --check=crc32"
            compext=".xz"
            shift
            ;;

        --zstd)
            if test "$compext" = ".xz"; then
                err "cannot mix XZ and ZSTD compression"
            fi
            compress="zstd --compress --quiet --stdout"
            compext=".zst"
            shift
            ;;

        -h|--help)
            usage
            exit 1
            ;;

        -*)
            warn "ignoring option $1"
            shift
            ;;

        *)
            if test -n "$destdir"; then
                err "unknown command-line options: $*"
            fi
            destdir="$1"
            shift
            ;;
    esac
done

if test -z "$destdir"; then
    err "destination directory was not specified"
fi

if test -d "$destdir"; then
    # BusyBox find does not support -empty; count entries instead
    if [ "$(find "$destdir" | wc -l)" -gt 1 ]; then
        warn "destination folder is not empty."
    fi
fi

if test -e .git/config; then
    $verbose "Checking that WHENCE file is formatted properly"
    ./check_whence.py || err "check_whence.py has detected errors."
fi

# sed -E is GNU-only; rewrite with basic BRE substitutions instead.
# File/RawFile lines: strip the keyword prefix and any surrounding quotes,
# then emit "K\tFILENAME" (tab-separated) so filenames with spaces are safe.
grep -E '^(RawFile|File):' WHENCE \
    | sed 's/^RawFile:/RawFile/;s/^File:/File/;s/"//g' \
    | awk '{k=$1; sub(/^[^ ]+ +/,""); printf "%s\t%s\n", k, $0}' \
    | while IFS="$(printf '\t')" read -r k f; do
        install -d "$destdir/$(dirname "$f")"
        $verbose "copying/compressing file $f$compext"
        if test "$compress" != "cat" && test "$k" = "RawFile"; then
            $verbose "compression will be skipped for file $f"
            if [ "$num_jobs" -gt 1 ]; then
                printf 'cat\t%s\t%s\n' "$f" "$destdir/$f" >> "$parallel_args_file"
            else
                cat "$f" > "$destdir/$f"
            fi
        else
            if [ "$num_jobs" -gt 1 ]; then
                printf '%s\t%s\t%s\n' "$compress" "$f" "$destdir/$f$compext" >> "$parallel_args_file"
            else
                $compress "$f" > "$destdir/$f$compext"
            fi
        fi
    done

if [ "$num_jobs" -gt 1 ]; then
    # Tab-separated columns: {1}=cmd+args  {2}=src  {3}=dest
    # parallel --colsep splits on the tab so spaces in paths are safe.
    parallel -j"$num_jobs" --colsep '\t' '{1} "{2}" > "{3}"' \
        < "$parallel_args_file"
    printf '' > "$parallel_args_file"
fi

# Link lines look like:  Link: some/name with spaces -> target with spaces
# Split on ' -> ' as a unit using awk so spaces inside names are preserved.
grep -E '^Link:' WHENCE \
    | sed 's/^Link: *//' \
    | awk '{
        idx = index($0, " -> ")
        if (idx > 0) {
            printf "%s\t%s\n", substr($0,1,idx-1), substr($0,idx+4)
        }
    }' \
    | while IFS="$(printf '\t')" read -r l t; do
        directory="$destdir/$(dirname "$l")"
        install -d "$directory"

        # BusyBox realpath lacks -m (allow non-existent) and -s (no symlink
        # resolution). Replicate by walking each component manually.
        target=$(
            cd "$directory" 2>/dev/null || exit 1
            result=$(pwd)
            set -f
            IFS=/
            for part in $t; do
                case "$part" in
                    '')   ;;
                    '.')  ;;
                    '..') result=$(dirname "$result") ;;
                    *)    result="$result/$part" ;;
                esac
            done
            printf '%s\n' "$result"
        )

        if test -e "$target"; then
            $verbose "creating link $l -> $t"
            if [ "$num_jobs" -gt 1 ]; then
                printf 'ln -s\t%s\t%s\n' "$t" "$destdir/$l" >> "$parallel_args_file"
            else
                ln -s "$t" "$destdir/$l"
            fi
        else
            $verbose "creating link $l$compext -> $t$compext"
            if [ "$num_jobs" -gt 1 ]; then
                printf 'ln -s\t%s\t%s\n' \
                    "$t$compext" "$destdir/$l$compext" >> "$parallel_args_file"
            else
                ln -s "$t$compext" "$destdir/$l$compext"
            fi
        fi
    done

if [ "$num_jobs" -gt 1 ]; then
    parallel -j"$num_jobs" --colsep '\t' '{1} "{2}" "{3}"' \
        < "$parallel_args_file"
fi

# Verify no broken symlinks.
# BusyBox find has no -xtype; use -type l then resolve each target manually.
# Relative targets are relative to the symlink's own directory.
find "$destdir" -type l | while read -r lnk; do
    lnk_target=$(readlink "$lnk")
    case "$lnk_target" in
        /*) check="$lnk_target" ;;
        *)  check="$(dirname "$lnk")/$lnk_target" ;;
    esac
    if ! test -e "$check"; then
        printf "ERROR: Broken symlink: %s -> %s\n" "$lnk" "$lnk_target" >&2
    fi
done
find "$destdir" -type l | while read -r lnk; do
    lnk_target=$(readlink "$lnk")
    case "$lnk_target" in
        /*) check="$lnk_target" ;;
        *)  check="$(dirname "$lnk")/$lnk_target" ;;
    esac
    test -e "$check" || exit 1
done || err "Broken symlinks found in $destdir"

exit 0

# vim: et sw=4 sts=4 ts=4