From 9070db4a14db87a21ee5f0bfe68acaa660eb2ac0 Mon Sep 17 00:00:00 2001
From: Asger Gitz-Johansen <asger.gitz@hotmail.com>
Date: Sun, 6 Oct 2024 19:45:18 +0200
Subject: [PATCH] feat: add message queue class

---
 pyproject.toml       |  3 +--
 src/scii/__init__.py |  2 --
 src/scii/__main__.py |  4 +++
 src/scii/main.py     | 12 +++++++++
 src/scii/mq.py       | 58 ++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 75 insertions(+), 4 deletions(-)
 delete mode 100644 src/scii/__init__.py
 create mode 100644 src/scii/__main__.py
 create mode 100644 src/scii/main.py
 create mode 100644 src/scii/mq.py

diff --git a/pyproject.toml b/pyproject.toml
index 3ab91e8..8fc564b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,11 +10,10 @@ readme = "README.md"
 requires-python = ">=3.12"
 dependencies = [
     "loguru",
-    "posix-ipc",
 ]
 
 [project.scripts]
-scih = "scih.main:main"
+scii = "scii.main:main"
 
 [project.optional-dependencies]
 build = [
diff --git a/src/scii/__init__.py b/src/scii/__init__.py
deleted file mode 100644
index 00cc1a4..0000000
--- a/src/scii/__init__.py
+++ /dev/null
@@ -1,2 +0,0 @@
-def hello() -> str:
-    return "Hello from scii!"
diff --git a/src/scii/__main__.py b/src/scii/__main__.py
new file mode 100644
index 0000000..4c6b07d
--- /dev/null
+++ b/src/scii/__main__.py
@@ -0,0 +1,4 @@
+from scii.main import main
+
+if __name__ == "__main__":
+    main()
diff --git a/src/scii/main.py b/src/scii/main.py
new file mode 100644
index 0000000..c86f219
--- /dev/null
+++ b/src/scii/main.py
@@ -0,0 +1,12 @@
+from loguru import logger
+
+from scii.mq import MessageQueue
+
+logger.catch
+def main():
+    logger.info("welcome to the SCI Interface")
+    with MessageQueue(rx="/sci_tx", tx="/sci_rx") as qu:
+        while True:
+            r = qu.receive()
+            if r is None:
+                break
diff --git a/src/scii/mq.py b/src/scii/mq.py
new file mode 100644
index 0000000..e66b050
--- /dev/null
+++ b/src/scii/mq.py
@@ -0,0 +1,58 @@
+from ctypes import cdll
+from ctypes import create_string_buffer
+
+from loguru import logger
+
+libc = cdll.LoadLibrary("libc.so.6")
+
+
+class MessageQueue:
+    """A simple abstraction over mq_* libc functions."""
+
+    def __init__(self, rx: str, tx: str) -> None:
+        self._rx = rx
+        self._tx = tx
+        self._rx_queue: int | None = None
+        self._tx_queue: int | None = None
+    
+    def __enter__(self) -> "MessageQueue":
+        self._rx_queue = libc.mq_open(bytes(self._rx, "utf-8"), 0, 666, None)
+        if not self._is_rx_valid():
+            libc.perror(b"mq_open")
+            logger.error("bad rx open")
+        self._tx_queue = libc.mq_open(bytes(self._tx, "utf-8"), 1, 666, None)
+        if not self._is_tx_valid():
+            libc.perror(b"mq_open")
+            logger.error("bad tx open")
+        return self
+
+    def __exit__(self, *_) -> None:
+        if self._is_rx_valid():
+            libc.mq_close(self._rx_queue)
+        if self._is_tx_valid():
+            libc.mq_close(self._tx_queue)
+        
+    def send(self, msg: str) -> None:
+        if not self._is_tx_valid():
+            raise RuntimeError(f"tx queue is invalid {self._tx_queue}")
+        res = libc.mq_send(self._tx_queue, bytes(msg, "utf-8"), len(msg), 1)
+        if res == -1:
+            libc.perror(b"mq_send")
+            logger.error("bad send")
+
+    def receive(self) -> str | None:
+        if not self._is_rx_valid():
+            raise RuntimeError(f"rx queue is invalid {self._rx_queue}")
+        result = create_string_buffer(b'\0' * 32)
+        res = libc.mq_receive(self._rx_queue, result, 8192, None)
+        if res == -1:
+            libc.perror(b"mq_receive")
+            logger.error("bad receive")
+            return None
+        return str(result.value)
+
+    def _is_rx_valid(self) -> bool:
+        return self._rx_queue is not None and self._rx_queue != -1 
+
+    def _is_tx_valid(self) -> bool:
+        return self._tx_queue is not None and self._tx_queue != -1