#!/usr/bin/env bash
# Checks the simulation is deterministic across builds and platforms, which desktop/web crossplay depends on.
#
# Fails if any source calls the maths library's transcendentals (src/dmath.h replaces them), then builds the game
# several ways and plays the same seeded bot matches in each (--balance with RPG_SEED), comparing the determinism hash
# they print:
#   gcc        GCC, optimised (the usual build)
#   gcc-fma    GCC for this CPU (with FMA if it has it, standing in for arm64's fused multiply-adds)
#   clang-O0   Clang, unoptimised
#   wasm       Emscripten, run under node (needs EMSDK, or emsdk_env.sh sourced)
#
# Usage: tools/determinism_check.sh [matches per seed, default 20] [seeds, default "1 2 3"]
set -euo pipefail

ROOT="$(cd "$(dirname "$0")/.." && pwd)"
OUT="$ROOT/build-check"
MATCHES="${1:-20}"
SEEDS="${2:-1 2 3}"

banned=$(grep -nE "std::(sin|cos|tan|atan2|atan|asin|acos|exp|exp2|expm1|log|log2|log10|log1p|pow|hypot|cbrt|sinh|cosh|tanh|lerp)\(|\b(sinf|cosf|tanf|atan2f|powf|expf|logf|log2f)\(|SDL_(sin|cos|tan|atan2|atan|pow|exp|log)f?\(" \
    "$ROOT"/src/*.cpp "$ROOT"/src/*.h | grep -v "src/dmath.h" || true)
if [ -n "$banned" ]; then
    echo "Maths library transcendentals in the source (use math_sin and friends from src/dmath.h):"
    echo "$banned"
    exit 1
fi

configure() # name, cmake arguments...
{
    local name="$1"
    shift
    if [ ! -f "$OUT/$name/build.ninja" ]; then
        cmake -S "$ROOT" -B "$OUT/$name" -G Ninja "$@" > "$OUT/$name.log" 2>&1
    fi
    cmake --build "$OUT/$name" >> "$OUT/$name.log" 2>&1 || {
        echo "$name failed to build, see $OUT/$name.log"
        exit 1
    }
}

mkdir -p "$OUT"
names=(gcc gcc-fma clang-O0)
configure gcc -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++
configure gcc-fma -DCMAKE_BUILD_TYPE=Release -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ \
    -DCMAKE_CXX_FLAGS=-march=native -DCMAKE_C_FLAGS=-march=native
configure clang-O0 -DCMAKE_BUILD_TYPE=Debug -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
if [ -n "${EMSDK:-}" ] || command -v emcmake > /dev/null; then
    [ -n "${EMSDK:-}" ] && source "$EMSDK/emsdk_env.sh" > /dev/null 2>&1
    if [ ! -f "$OUT/wasm/build.ninja" ]; then
        emcmake cmake -S "$ROOT" -B "$OUT/wasm" -G Ninja -DCMAKE_BUILD_TYPE=Release -DRPG_NODE=ON > "$OUT/wasm.log" 2>&1
    fi
    cmake --build "$OUT/wasm" >> "$OUT/wasm.log" 2>&1 || {
        echo "wasm failed to build, see $OUT/wasm.log"
        exit 1
    }
    names+=(wasm)
else
    echo "Emscripten not found (set EMSDK): skipping the wasm build."
fi

hash_get() # name, seed
{
    local run=("$OUT/$1/smack-a-brother")
    [ "$1" = wasm ] && run=(node "$OUT/wasm/smack-a-brother.js")
    (cd "$OUT/$1" && RPG_SEED="$2" "${run[@]}" --balance "$MATCHES" 2>&1 | grep -oE "hash: [0-9a-f]+" | cut -d' ' -f2)
}

failed=0
for seed in $SEEDS; do
    line="seed $seed:"
    first=""
    for name in "${names[@]}"; do
        hash=$(hash_get "$name" "$seed")
        line+="  $name $hash"
        [ -z "$first" ] && first="$hash"
        [ "$hash" != "$first" ] && failed=1
    done
    echo "$line"
done
if [ "$failed" = 1 ]; then
    echo "DESYNC: the builds disagree."
    exit 1
fi
echo "Deterministic: every build agrees."