#!/bin/bash
# prebuild — stage the kernel source tarball this PKGBUILD expects.
#
# linux-ampere-fourier's source is a snapshot of marfrit/linux-rk3588-marfrit
# @ f8f3ad9 (260MB), too big to commit to marfrit-packages and currently
# unpushable to Gitea (boltzmann's working clone is shallow; gitea push
# refuses shallow updates). Hosting the tarball outside Gitea would need
# infrastructure setup that's not in scope for the first iteration.
#
# So: produce the tarball locally from the kernel working tree just
# before makepkg runs. Idempotent — if an existing tarball matches the
# expected sha256 we skip the archive step.
#
# Run from this directory:  cd arch/linux-ampere-fourier && ./prebuild.sh
# Override the kernel-tree location:  LINUX_RK3588_MARFRIT_TREE=/path ./prebuild.sh
#
# Default tree location matches the boltzmann/ampere convention from
# kernel-agent issue #6: $HOME/src/linux-rockchip.
set -euo pipefail

TREE="${LINUX_RK3588_MARFRIT_TREE:-${HOME}/src/linux-rockchip}"
COMMIT=48a8c785de7f5320513052a64e544c6310d7b273
# Generated tarball sha varies with gzip version — script warns-not-fails.
# Leave EXPECTED empty for fresh kafr2 builds; first successful build can
# pin a canonical sha here if a reproducibility audit needs it.
SHA256_EXPECTED=

HERE="$(cd "$(dirname "$0")" && pwd)"
OUTPUT="${HERE}/linux-rk3588-marfrit-${COMMIT:0:7}.tar.gz"

if [ -f "$OUTPUT" ]; then
    have=$(sha256sum "$OUTPUT" | cut -d' ' -f1)
    if [ "$have" = "$SHA256_EXPECTED" ]; then
        echo "prebuild: $OUTPUT already exists with correct sha256"
        exit 0
    else
        echo "prebuild: existing $OUTPUT sha mismatch (have=$have, want=$SHA256_EXPECTED) — regenerating" >&2
        rm -f "$OUTPUT"
    fi
fi

if [ ! -d "$TREE/.git" ]; then
    echo "prebuild: kernel tree not at $TREE" >&2
    echo "          set LINUX_RK3588_MARFRIT_TREE=/path/to/linux-rockchip and retry" >&2
    exit 2
fi

cd "$TREE"

if ! git cat-file -e "$COMMIT" 2>/dev/null; then
    echo "prebuild: commit $COMMIT not found in $TREE" >&2
    echo "          fetch the linux-rk3588-marfrit branch first:" >&2
    echo "          git fetch <remote> linux-rk3588-marfrit" >&2
    exit 3
fi

echo "prebuild: generating archive from $TREE @ $COMMIT..."
git archive --format=tar.gz --prefix=linux-rk3588-marfrit/ "$COMMIT" -o "$OUTPUT"

# git archive emits a deterministic tar stream but gzip compression may
# vary by version. The sha256 check is informational; warn-don't-fail.
have=$(sha256sum "$OUTPUT" | cut -d' ' -f1)
if [ "$have" != "$SHA256_EXPECTED" ]; then
    echo "prebuild: WARNING $OUTPUT sha=$have (canonical=$SHA256_EXPECTED)" >&2
    echo "          probably a gzip-version difference; tar payload should be identical" >&2
fi

echo "prebuild: wrote $OUTPUT ($(du -h "$OUTPUT" | cut -f1), sha=$have)"