#!/usr/bin/env bash
# libwai for C on Linux: the static library, wai.h and the pkg-config file wai.pc, for one target.
#
#   bash wai/quickstart/build-libwai.sh <out-dir> [--target <triple>] [--version <v>]
#
# Builds wai/wai-rs's library, release and --locked, with the feature native_sink alone: the C
# interface of the envelope (pack, unpack and select, the WAI2 rendition table, an integer
# payload's declared cost) and of the native sink (extensions/native-sink.md §9), the interface the
# Swift package's WaiFFI.xcframework and the Android library carry. Pure Rust: it needs nothing but
# the C runtime. wai.h also declares the codec wrappers (src/ffi_codecs.rs, feature codecs) and the
# neural decoders (src/ffi_neural.rs, feature neural), which need codec and model libraries this
# library does not hold: its README says so, and the library is held below to exactly the
# functions of src/ffi.rs and src/ffi_sink.rs.
#
# The library is static, lib/libwai.a, for a glibc target (x86_64- or aarch64-unknown-linux-gnu),
# built without crt-static. A program that links it carries it: nothing of libwai is looked for at
# run time, and the C runtime's symbols bind when the program is linked, to the glibc it is linked
# against. wai.pc names it with the system libraries it needs (rustc's native-static-libs), so
# `pkg-config --libs wai` links it as it is; its prefix is the directory it is in (${pcfiledir}),
# so the archive works wherever it is unpacked.
#
# Writes <out-dir>/libwai-<version>-<triple>.tar.gz holding include/wai.h, lib/libwai.a,
# lib/pkgconfig/wai.pc, README.md and LICENSE, with <archive>.sha256 beside it. Before it packages:
#   - the header the build generates (build.rs regenerates include/wai.h) is the committed one,
#     byte for byte, so the archive's header is the repository's (run in a fresh target directory,
#     as a release does, so the build script runs);
#   - the header declares nothing but wai_* and WAI_* names, and every function it declares is one
#     of the five files of the C interface; the library defines exactly the wai_* functions of
#     src/ffi.rs and src/ffi_sink.rs (wai/quickstart/libwai_interface.py).
# Where the target is this machine's, wai/quickstart/test/c-library.sh then compiles a C program
# against the archive through pkg-config, links it and runs it.
set -euo pipefail
usage() { echo "usage: bash wai/quickstart/build-libwai.sh <out-dir> [--target <triple>] [--version <v>]" >&2; exit 2; }
die() { echo "build-libwai.sh: $*" >&2; exit 1; }
[ $# -ge 1 ] || usage
ROOT=$(cd "$(dirname "$0")/../.." && pwd)
RS="$ROOT/wai/wai-rs"
OUT=$(mkdir -p "$1" && cd "$1" && pwd); shift
TRIPLE="" VERSION=""
while [ $# -gt 0 ]; do
  case "$1" in
    --target) TRIPLE="$2"; shift 2 ;;
    --version) VERSION="$2"; shift 2 ;;
    *) usage ;;
  esac
done
HOST=$(rustc -vV | sed -n 's/^host: //p')
TRIPLE=${TRIPLE:-$HOST}
case "$TRIPLE" in
  x86_64-unknown-linux-gnu | aarch64-unknown-linux-gnu) ;;
  *) echo "build-libwai.sh: $TRIPLE: the archive is built for x86_64- or aarch64-unknown-linux-gnu" >&2; exit 2 ;;
esac
case "${RUSTFLAGS:-} ${CARGO_ENCODED_RUSTFLAGS:-}" in
  *crt-static*) die "RUSTFLAGS asks for crt-static: libwai.a is built against the dynamic C runtime" ;;
esac
VERSION=${VERSION:-$(sed -n 's/^version = "\(.*\)"$/\1/p' "$RS/Cargo.toml" | head -1)}
NAME="libwai-$VERSION-$TRIPLE"
FEATURES=(--no-default-features --features native_sink)
# A target directory of its own: wai also builds as a cdylib, so its rlib's file name carries no
# hash, and another feature set of the crate in the same directory would overwrite this one.
TD="${CARGO_TARGET_DIR:-$RS/target}/libwai-c"
STAGE=$(mktemp -d)
trap 'rm -rf "$STAGE"' EXIT
cp "$RS/include/wai.h" "$STAGE/wai.h.committed"

# rustc names the system libraries a static library needs when it links one
# (--print=native-static-libs); a build that compiles nothing prints nothing, so then the crate is
# compiled again.
build() {
  ( cd "$RS" && CARGO_TARGET_DIR="$TD" cargo rustc --locked --release --lib "${FEATURES[@]}" --target "$TRIPLE" \
      -- --print=native-static-libs ) 2>&1 | tee "$STAGE/build.log" >&2
}
native_libs() { sed -n 's/^.*note: native-static-libs: //p' "$STAGE/build.log" | tail -1; }
build || die "the build of libwai failed"
NATIVE=$(native_libs)
if [ -z "$NATIVE" ]; then
  ( cd "$RS" && CARGO_TARGET_DIR="$TD" cargo clean --release --target "$TRIPLE" -p wai ) >&2
  build || die "the build of libwai failed"
  NATIVE=$(native_libs)
fi
[ -n "$NATIVE" ] || die "rustc named no native-static-libs for libwai.a"
LIB="$TD/$TRIPLE/release/libwai.a"
[ -f "$LIB" ] || die "no $LIB"

cmp -s "$STAGE/wai.h.committed" "$RS/include/wai.h" || {
  diff -u "$STAGE/wai.h.committed" "$RS/include/wai.h" | head -60 >&2 || true
  die "the build regenerated wai/wai-rs/include/wai.h and it is not the committed header: commit the regenerated one"
}

D="$STAGE/$NAME"
mkdir -p "$D/include" "$D/lib/pkgconfig"
cp "$RS/include/wai.h" "$D/include/wai.h"
# The library without its debugging sections (the standard library's among them): a program links
# the same code from it, and the symbols it links by are kept.
cp "$LIB" "$D/lib/libwai.a"
strip --strip-debug "$D/lib/libwai.a" || die "strip could not take the debugging sections out of libwai.a"
nm -g --defined-only "$D/lib/libwai.a" > "$STAGE/nm.txt" 2>/dev/null || die "nm could not read libwai.a"
python3 -I "$ROOT/wai/quickstart/libwai_interface.py" --root "$ROOT" --nm "$STAGE/nm.txt" >&2 \
  || die "the header or the library is not the C interface it should be"

cat > "$D/lib/pkgconfig/wai.pc" <<PC
prefix=\${pcfiledir}/../..
libdir=\${prefix}/lib
includedir=\${prefix}/include

Name: wai
Description: WAI's C interface: the envelope and the native sink (wai-rs, feature native_sink), static
URL: https://wai.transaction.science
Version: $VERSION
Cflags: -I\${includedir}
Libs: -L\${libdir} -lwai $NATIVE
PC
cp "$ROOT/wai/quickstart/libwai.md" "$D/README.md"
cp "$ROOT/wai/LICENSE" "$D/LICENSE"
chmod 644 "$D/include/wai.h" "$D/lib/libwai.a" "$D/lib/pkgconfig/wai.pc" "$D/README.md" "$D/LICENSE"
# The same bytes for the same inputs: sorted names, fixed owner and times.
tar --sort=name --owner=0 --group=0 --numeric-owner --mtime='2026-01-01 00:00Z' -C "$STAGE" -cf - "$NAME" | gzip -n -9 > "$OUT/$NAME.tar.gz"
( cd "$OUT" && sha256sum "$NAME.tar.gz" > "$NAME.tar.gz.sha256" )
echo "packaged $OUT/$NAME.tar.gz ($(cut -d' ' -f1 "$OUT/$NAME.tar.gz.sha256"), $(du -h "$OUT/$NAME.tar.gz" | cut -f1)); wai.pc links: -lwai $NATIVE"
if [ "$TRIPLE" = "$HOST" ]; then
  bash "$ROOT/wai/quickstart/test/c-library.sh" "$OUT/$NAME.tar.gz"
fi