From b8bd9e1fe168495f4e0aceebd3f1e77d5e3795ad Mon Sep 17 00:00:00 2001
From: Akira Moroo <retrage01@gmail.com>
Date: Sat, 21 Jun 2025 18:44:55 +0900
Subject: [PATCH] Add WebAssembly build to CI

Signed-off-by: Akira Moroo <retrage01@gmail.com>
---
 .github/workflows/ci.yml |  4 +++-
 .gitignore               |  4 ++++
 Makefile                 | 14 ++++++++++++++
 README.md                | 11 +++++++++++
 docs/AGENT_PROMPTS.md    |  1 +
 main.cpp                 |  6 ++++++
 web/index.html           | 24 ++++++++++++++++++++++++
 7 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 web/index.html

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 20ad38a..5941684 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,7 @@ jobs:
           wget https://packages.apache.org/artifactory/arrow/$(lsb_release --id --short | tr 'A-Z' 'a-z')/apache-arrow-apt-source-latest-$(lsb_release --codename --short).deb
           sudo apt install -y ./apache-arrow-apt-source-latest-$(lsb_release --codename --short).deb
           sudo apt-get update
-          sudo apt-get install -y g++ make clang-tidy clang-format python3 python3-pip libarrow-dev libparquet-dev
+          sudo apt-get install -y g++ make clang-tidy clang-format python3 python3-pip libarrow-dev libparquet-dev emscripten
           pip3 install pandas pyarrow pytest
       - name: Build
         run: make USE_ARROW=${{ matrix.arrow }}
@@ -32,3 +32,5 @@ jobs:
         run: make tidy
       - name: Run test
         run: make USE_ARROW=${{ matrix.arrow }} test
+      - name: Build WebAssembly
+        run: make web
diff --git a/.gitignore b/.gitignore
index c6795f1..865bdef 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,6 @@
 main
 spikes.bin
+web/main.js
+web/main.wasm
+web/main.data
+test/__pycache__/
diff --git a/Makefile b/Makefile
index c4064d9..6cf2337 100644
--- a/Makefile
+++ b/Makefile
@@ -35,3 +35,17 @@ submodule:
 	git submodule update --init --recursive
 
 .PHONY: clean format tidy test submodule bench
+
+WEB_DIR = web
+WEB_TARGET = $(WEB_DIR)/main.js
+
+$(WEB_TARGET): main.cpp
+	mkdir -p $(WEB_DIR)
+	em++ $< -O3 -std=c++20 -s WASM=1 -s MODULARIZE=1 \
+	  -s EXPORTED_FUNCTIONS="['_run_simulation_c']" \
+	  -s EXPORTED_RUNTIME_METHODS="['cwrap','FS']" \
+	  --preload-file test -o $(WEB_TARGET)
+
+web: $(WEB_TARGET)
+
+.PHONY: web
diff --git a/README.md b/README.md
index db47317..7bb3805 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,17 @@ make
 This produces an executable named `main`. To enable Apache Arrow support pass
 `USE_ARROW=1` (requires Arrow C++ libraries with `pkg-config` files).
 
+### WebAssembly
+
+Emscripten can build the simulator to WebAssembly. Install `em++` and run:
+
+```bash
+make web
+```
+
+The generated `web/` directory contains `main.js`, `main.wasm`, and a small
+`index.html` that runs the example dataset in your browser.
+
 ## Running
 
 Run the simulator by providing a connectome CSV file and lists of active and silent neurons. When built with Arrow support you may provide a Parquet file instead:
diff --git a/docs/AGENT_PROMPTS.md b/docs/AGENT_PROMPTS.md
index 85375ec..9acd849 100644
--- a/docs/AGENT_PROMPTS.md
+++ b/docs/AGENT_PROMPTS.md
@@ -9,6 +9,7 @@ The project simulates spikes in a Drosophila connectome using a leaky integrate-
 - Keep the simulator self contained in `main.cpp` unless new modules are justified.
 - Unit tests live under `test/` and should be expanded when new features are added.
 - Large datasets are provided via the optional `Drosophila_brain_model` submodule and should not be committed directly to the repository. Support for loading Parquet files via Apache Arrow is optional and can be enabled by building with `USE_ARROW=1`.
+- WebAssembly builds can be generated with `make web` when Emscripten is available.
 
 ## Pull Request Guidance
 
diff --git a/main.cpp b/main.cpp
index b862152..00506d2 100644
--- a/main.cpp
+++ b/main.cpp
@@ -284,6 +284,12 @@ size_t run_simulation(const string &csv, const string &pq, const string &act,
   return S.spikes.size();
 }
 
+extern "C" size_t run_simulation_c(const char *csv, const char *pq,
+                                   const char *act, const char *sil, size_t T) {
+  return run_simulation(csv ? string(csv) : "", pq ? string(pq) : "",
+                        act ? string(act) : "", sil ? string(sil) : "", T);
+}
+
 #ifndef BENCH_LIB
 int main(int argc, char **argv) {
   string csv, pq, act, sil;
diff --git a/web/index.html b/web/index.html
new file mode 100644
index 0000000..6371dc0
--- /dev/null
+++ b/web/index.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>Drosophila WASM Demo</title>
+</head>
+<body>
+    <h1>Drosophila WebAssembly Demo</h1>
+    <button id="run">Run Example</button>
+    <pre id="out"></pre>
+    <script type="module">
+        import ModuleFactory from './main.js';
+        ModuleFactory().then(Module => {
+            document.getElementById('run').onclick = () => {
+                const run = Module.cwrap('run_simulation_c', 'number',
+                    ['string','string','string','string','number']);
+                const spikes = run('/test/test_connectome.csv', '',
+                    '/test/active.txt', '/test/silent.txt', 10);
+                document.getElementById('out').textContent = 'Spikes: ' + spikes;
+            };
+        });
+    </script>
+</body>
+</html>