#!/usr/bin/env bash
#
# Generate the CPython frozen getpath.py header into ignored build output.
#
# CPython's build documents this target in Makefile.pre.in:
#   Python/frozen_modules/getpath.h: Modules/getpath.py ...
#       Programs/_freeze_module.py getpath Modules/getpath.py Python/frozen_modules/getpath.h
#
# This script intentionally writes under build/generated/cpython/... so the
# repository does not track generated bytecode headers or vendor files.
#
# Usage:
#   scripts/generate-getpath-frozen.sh [output-root]
#
# Output:
#   <output-root>/cpython/Python/frozen_modules/getpath.h
#   default output-root: build/generated

set -u

REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
CPYTHON_ROOT="$REPO_ROOT/cpython"
OUTPUT_ROOT="${1:-$REPO_ROOT/build/generated}"
OUT_DIR="$OUTPUT_ROOT/cpython/Python/frozen_modules"
OUT_HEADER="$OUT_DIR/getpath.h"
FREEZE_SCRIPT="$CPYTHON_ROOT/Programs/_freeze_module.py"
INPUT="$CPYTHON_ROOT/Modules/getpath.py"

usage() {
    sed -n '11,19p' "$REPO_ROOT/scripts/generate-getpath-frozen.sh"
}

if [ "${1:-}" = "-h" ] || [ "${1:-}" = "--help" ]; then
    usage
    exit 0
fi

for required in "$CPYTHON_ROOT" "$FREEZE_SCRIPT" "$INPUT"; do
    if [ ! -e "$required" ]; then
        echo "generate-getpath-frozen: missing prerequisite: $required" >&2
        exit 2
    fi
done

if ! command -v python3 >/dev/null 2>&1; then
    echo "generate-getpath-frozen: missing prerequisite: python3" >&2
    exit 2
fi

mkdir -p "$OUT_DIR"
python3 "$FREEZE_SCRIPT" getpath "$INPUT" "$OUT_HEADER"
status=$?
if [ "$status" -ne 0 ]; then
    echo "generate-getpath-frozen: _freeze_module.py failed with exit $status" >&2
    exit "$status"
fi

if [ ! -s "$OUT_HEADER" ]; then
    echo "generate-getpath-frozen: expected nonempty output missing: $OUT_HEADER" >&2
    exit 2
fi

printf '%s\n' "${OUT_HEADER#$REPO_ROOT/}"