From d2614321c028eab35e2882ab4944c43f24b01489 Mon Sep 17 00:00:00 2001
From: Daniel Jones <daniel@jones.org.uk>
Date: Sun, 8 Sep 2024 18:00:44 +0200
Subject: [PATCH] AudioGraphConfig: Add support for reading from a
 user-specified config path

---
 source/include/signalflow/core/config.h | 15 ++++++++++++++
 source/src/core/config.cpp              | 26 +++++++++++++++++++++++--
 source/src/python/config.cpp            |  1 +
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/source/include/signalflow/core/config.h b/source/include/signalflow/core/config.h
index f2fd2330..83980898 100644
--- a/source/include/signalflow/core/config.h
+++ b/source/include/signalflow/core/config.h
@@ -14,8 +14,20 @@ namespace signalflow
 class AudioGraphConfig
 {
 public:
+    /**--------------------------------------------------------------------------------
+     * Create a new AudioGraphConfig, reading configuration from the default path
+     * (~/.signalflow/config)
+     *
+     *--------------------------------------------------------------------------------*/
     AudioGraphConfig();
 
+    /**--------------------------------------------------------------------------------
+     * Create a new AudioGraphConfig, reading from a user-specified path.
+     * If the path does not exist, raises a runtime exception.
+     *
+     *--------------------------------------------------------------------------------*/
+    AudioGraphConfig(std::string config_path);
+
     /**--------------------------------------------------------------------------------
      * Get the preferred sample rate.
      * To query the actual sample rate, use AudioGraph::get_sample_rate().
@@ -152,6 +164,9 @@ class AudioGraphConfig
     void print() const;
 
 private:
+    void parse_file(std::ifstream &input);
+    void parse_env();
+
     unsigned int sample_rate = 0;
     unsigned int input_buffer_size = 0;
     unsigned int output_buffer_size = 0;
diff --git a/source/src/core/config.cpp b/source/src/core/config.cpp
index 2d408a66..9ec10e00 100644
--- a/source/src/core/config.cpp
+++ b/source/src/core/config.cpp
@@ -70,14 +70,33 @@ std::map<std::string, std::map<std::string, std::string>> parse_config(std::istr
 
 AudioGraphConfig::AudioGraphConfig()
 {
-    const std::string config_path = SIGNALFLOW_USER_DIR + "/config";
+    std::string config_path = SIGNALFLOW_USER_DIR + "/config";
+    std::ifstream input(config_path);
+
+    // Don't throw an error if the user config file does not exist,
+    // just continue silently.
+    if (input.good())
+    {
+        parse_file(input);
+    }
+
+    parse_env();
+}
 
+AudioGraphConfig::AudioGraphConfig(std::string config_path)
+{
     std::ifstream input(config_path);
     if (!input.good())
     {
-        return;
+        throw std::runtime_error("Config path could not be read: " + config_path);
     }
 
+    parse_file(input);
+    parse_env();
+}
+
+void AudioGraphConfig::parse_file(std::ifstream &input)
+{
     auto sections = parse_config(input);
     for (auto section_pair : sections)
     {
@@ -137,7 +156,10 @@ AudioGraphConfig::AudioGraphConfig()
             }
         }
     }
+}
 
+void AudioGraphConfig::parse_env()
+{
     if (getenv("SIGNALFLOW_SAMPLE_RATE"))
     {
         this->sample_rate = atoi(getenv("SIGNALFLOW_SAMPLE_RATE"));
diff --git a/source/src/python/config.cpp b/source/src/python/config.cpp
index 1dd5197d..c62aeeff 100644
--- a/source/src/python/config.cpp
+++ b/source/src/python/config.cpp
@@ -7,6 +7,7 @@ void init_python_config(py::module &m)
      *-------------------------------------------------------------------------------*/
     py::class_<AudioGraphConfig>(m, "AudioGraphConfig", "Configuration options for the AudioGraph")
         .def(py::init<>())
+        .def(py::init<std::string>(), R"pbdoc(Read an AudioGraphConfig from a user-specified path)pbdoc")
         .def("print", &AudioGraphConfig::print, R"pbdoc(Print the AudioGraphConfig to stdout)pbdoc")
         .def_property("sample_rate", &AudioGraphConfig::get_sample_rate, &AudioGraphConfig::set_sample_rate)
         .def_property("input_buffer_size", &AudioGraphConfig::get_input_buffer_size, &AudioGraphConfig::set_input_buffer_size)