# Building on a new platform

## Upstream prerequisites

-   A recent Qt, PyQt5 and PyQtWebEngine must work on your platform. Chances are wheels
    for your platform are not available on PyPI, so you will need to have a working
    version installed already, either from your Linux distro's archives, or by building
    from source.
-   Rust and Node must support your platform.
-   If the Bazel Rust and Node rules do not support your platform, extra work may be required.

## 32 bit builds

Bazel does not support running on a 32-bit host. It may be theoretically
possible to cross-compile from a 64-bit host, but this is not something we've
tried, and it will likely not work out of the box.

## Protobuf & Python

-   Edit /platforms/BUILD.bzl and add the new platform. Available platforms
    and CPUs can be found here: https://github.com/bazelbuild/platforms
-   Edit /protobuf.bzl and add the new platform and a link to a protoc binary.
-   Edit /pylib/anki/BUILD.bazel and add the new platform and the relevant
    Python wheel name for your platform.

Example of the above changes:
https://github.com/ankitects/anki/commit/db3308e788f20b188e84add40d6a1dce5bf726a0

-   We need to tell the build process to use your local PyQt5 install, instead of
    fetching it from PyPI. Locate your Python site-packages folder where the PyQt5
    folder is, and add the following to user.bazelrc in the project folder root:

```
build --action_env=PYTHON_SITE_PACKAGES=/path/to/site-packages/
```

-   Anki uses the Python 'orjson' module to speed up DB access. If you're on a
    platform that can not build orjson, you can remove it from
    python/requirements.txt to skip it during running/building, but DB operations
    will be slower.

    The py_wheel() rule in pylib/anki/BUILD.bazel adds an orjson requirement to
    the generated Anki wheel. If you have removed orjson, you'll want to
    remove that line. If you have successfully built orjson for another platform,
    you'll want to adjust that line to include your platform.

## Rust

-   Ensure you have Rust installed (eg via rustup)
-   Edit /Cargo.toml in this project, and add your platform
    to the targets. Check that the platform [is supported](https://github.com/bazelbuild/rules_rust/blob/master/rust/platform/platform.bzl) by rules_rust; if it is not, you'll
    need to send a PR to them adding it. You can test your change locally by modifying
    /repos.bzl in this project to point to a local rules_rust checkout.
-   Edit /cargo/BUILD.request.bazel and add the new platform.
-   Run update.py in the /cargo folder.

Examples of the required changes:

-   https://github.com/ankitects/anki/commit/eca27b371000e77b68cb4c790b44848507ca3883
-   https://github.com/ankitects/anki/commit/3f3f4b5c3640a7d1f4eec02f326fda93214ec34b

## NodeJS

If node doesn't provide a binary for your platform and you have a local copy
installed, you can create a local_node folder in the project root, symlink in
your local installation, and modify defs.bzl.

```patch
diff --git a/defs.bzl b/defs.bzl
index eff3d9df2..fb2e9f7fe 100644
--- a/defs.bzl
+++ b/defs.bzl
@@ -41,7 +41,15 @@ def setup_deps():
         python_runtime = "@python//:python",
     )

-    node_repositories(package_json = ["@ankidesktop//ts:package.json"])
+    native.local_repository(
+        name = "local_node",
+        path = "local_node",
+    )
+
+    node_repositories(
+        package_json = ["@ankidesktop//ts:package.json"],
+        vendored_node = "@local_node//:node",
+    )

     yarn_install(
         name = "npm",
diff --git a/local_node/BUILD.bazel b/local_node/BUILD.bazel
new file mode 100644
index 000000000..aa0c473ae
--- /dev/null
+++ b/local_node/BUILD.bazel
@@ -0,0 +1 @@
+exports_files(["node/bin/node"] + glob(["node/lib/node_modules/**"]))
diff --git a/local_node/WORKSPACE b/local_node/WORKSPACE
new file mode 100644
index 000000000..e69de29bb
diff --git a/local_node/node/bin/node b/local_node/node/bin/node
new file mode 120000
index 000000000..d7b371472
--- /dev/null
+++ b/local_node/node/bin/node
@@ -0,0 +1 @@
+/usr/local/bin/node
\ No newline at end of file
diff --git a/local_node/node/lib/node_modules b/local_node/node/lib/node_modules
new file mode 120000
index 000000000..23dd0736e
--- /dev/null
+++ b/local_node/node/lib/node_modules
@@ -0,0 +1 @@
+/usr/local/lib/node_modules
\ No newline at end of file
```

## Submitting changes

If the changes to support your platform do not require platform-specific hacks,
a PR that adds them is welcome - please see [Contributing](./contributing.md) for more.