#!/usr/bin/env bash
# Spike: what it costs to link the OCaml compiler into a native Flan dev build.
#
# Deliberately NOT a dune target. The root `dune` only excludes old-ocaml/, so a
# dune file here would land in @default and make the spike part of the build.
# Instead this drives ocamlfind and clang by hand, against the flan.cmxa that
# dune already produces. Run it from anywhere:  bash spike/embed/run.sh
set -u

here=$(cd "$(dirname "$0")" && pwd)
root=$(cd "$here/../.." && pwd)
cd "$here" || exit 1

OCAMLLIB=$(ocamlopt -where)
CAMLINC="-I$OCAMLLIB"
# OCaml 5.2's marshaller is compressed, so -output-complete-obj pulls in zstd.
SYSLIBS="-lm -lpthread -ldl -lzstd"

step() { printf '\n=== %s ===\n' "$1"; }

# ---------------------------------------------------------------- 1. smallest
step "1. smallest link: C main() -> caml_startup -> OCaml callback"
ocamlfind ocamlopt -package unix -linkpkg -output-complete-obj \
  -o embed1.o hello_ml.ml || exit 1
clang $CAMLINC harness1.c embed1.o -o spike1 $SYSLIBS || exit 1
./spike1 || echo "spike1 FAILED"
ls -l spike1 | awk '{print "spike1 size: " $5 " bytes"}'

# ------------------------------------------------------- 2. the real compiler
step "2. link the whole flan compiler (flan.cmxa) into a C binary"
CMXA="$root/_build/default/lib/flan.cmxa"
if [ ! -f "$CMXA" ]; then
  echo "no $CMXA -- run 'dune build --root .' first"; exit 1
fi
ocamlfind ocamlopt -package unix -linkpkg -output-complete-obj \
  -I "$root/_build/default/lib/.flan.objs/byte" \
  -I "$root/_build/default/lib/.flan.objs/native" \
  -o embed2.o "$CMXA" whole_ml.ml || exit 1
clang $CAMLINC harness2.c embed2.o -o spike2 $SYSLIBS || exit 1
(cd "$root" && "$here/spike2" test/programs/edn.flan) || echo "spike2 FAILED"
ls -l spike2 | awk '{print "spike2 size: " $5 " bytes"}'
ls -l "$root/_build/default/bin/main.exe" | awk '{print "main.exe size: " $5 " bytes"}'
clang $CAMLINC baseline.c -o baseline
ls -l baseline | awk '{print "bare C baseline: " $5 " bytes"}'

# ------------------------------------------------------------- 3. with stubs
step "3. the same, with the project's own C stubs compiled in"
ocamlfind ocamlopt -package unix -linkpkg -output-complete-obj \
  -I "$root/_build/default/lib/.flan.objs/byte" \
  -I "$root/_build/default/lib/.flan.objs/native" \
  -o embed3.o "$CMXA" stubs_ml.ml dynload_stubs.c || exit 1
clang $CAMLINC harness3.c embed3.o -o spike3 $SYSLIBS || exit 1
./spike3 || echo "spike3 FAILED"

# ------------------------------------------ 4. threads: game owns main thread
step "4. threads: C main runs the 'game loop', OCaml starts on another thread"
ocamlfind ocamlopt -thread -package unix,threads.posix -linkpkg -output-complete-obj \
  -I "$root/_build/default/lib/.flan.objs/byte" \
  -I "$root/_build/default/lib/.flan.objs/native" \
  -o embed4.o "$CMXA" thread_ml.ml || exit 1
clang $CAMLINC harness4.c embed4.o -o spike4 $SYSLIBS || exit 1
(cd "$root" && "$here/spike4" test/programs/edn.flan) || echo "spike4 FAILED"

# ------------------------------------------------------------ 5. signals
step "5. signals: who owns SIGSEGV across caml_startup"
clang $CAMLINC harness5.c embed2.o -o spike5 $SYSLIBS || exit 1
./spike5 || echo "spike5 exited nonzero"

# ------------------------------------------------------- 6. GC vs raw memory
step "6. GC: does a compaction move or touch a C-owned arena"
ocamlfind ocamlopt -package unix -linkpkg -output-complete-obj \
  -o embed6.o gc_ml.ml || exit 1
clang $CAMLINC harness6.c embed6.o -o spike6 $SYSLIBS || exit 1
./spike6 || echo "spike6 FAILED"

printf '\nspike: done\n'