koan-core 0.18.0

use std::mem;
use std::ptr;

use core_foundation::base::TCFType;
use core_foundation::string::CFString;
use coreaudio_sys::*;
use thiserror::Error;

#[derive(Debug, Error)]
pub enum DeviceError {
    #[error("CoreAudio error: {0}")]
    OSStatus(i32),
    #[error("no output devices found")]
    NoDevices,
    #[error("device not found: {0}")]
    NotFound(AudioDeviceID),
    #[error("device not found by name: {0}")]
    NotFoundByName(String),
}

type Result<T> = std::result::Result<T, DeviceError>;

fn check(status: OSStatus) -> Result<()> {
    if status == 0 {
        Ok(())
    } else {
        Err(DeviceError::OSStatus(status))
    }
}

#[derive(Debug, Clone)]
pub struct AudioDevice {
    pub id: AudioDeviceID,
    pub name: String,
    pub sample_rates: Vec<f64>,
}

/// Get the default output device ID.
pub fn default_output_device() -> Result<AudioDeviceID> {
    let property = AudioObjectPropertyAddress {
        mSelector: kAudioHardwarePropertyDefaultOutputDevice,
        mScope: kAudioObjectPropertyScopeGlobal,
        mElement: kAudioObjectPropertyElementMain,
    };

    let mut device_id: AudioDeviceID = 0;
    let mut size = mem::size_of::<AudioDeviceID>() as u32;

    // SAFETY: `device_id` is a stack-allocated AudioDeviceID with correct size.
    // CoreAudio writes a single u32 device ID into the provided buffer.
    check(unsafe {
        AudioObjectGetPropertyData(
            kAudioObjectSystemObject,
            &property,
            0,
            ptr::null(),
            &mut size,
            &mut device_id as *mut _ as *mut _,
        )
    })?;

    if device_id == 0 {
        return Err(DeviceError::NoDevices);
    }

    Ok(device_id)
}

/// List all output devices.
pub fn list_output_devices() -> Result<Vec<AudioDevice>> {
    let property = AudioObjectPropertyAddress {
        mSelector: kAudioHardwarePropertyDevices,
        mScope: kAudioObjectPropertyScopeGlobal,
        mElement: kAudioObjectPropertyElementMain,
    };

    let mut size: u32 = 0;
    // SAFETY: Querying data size only — no output buffer, just writes to `size`.
    check(unsafe {
        AudioObjectGetPropertyDataSize(
            kAudioObjectSystemObject,
            &property,
            0,
            ptr::null(),
            &mut size,
        )
    })?;

    let device_count = size as usize / mem::size_of::<AudioDeviceID>();
    let mut device_ids = vec![0u32; device_count];

    // SAFETY: `device_ids` is pre-allocated to exactly the size returned by
    // GetPropertyDataSize. CoreAudio fills it with `device_count` AudioDeviceIDs.
    check(unsafe {
        AudioObjectGetPropertyData(
            kAudioObjectSystemObject,
            &property,
            0,
            ptr::null(),
            &mut size,
            device_ids.as_mut_ptr() as *mut _,
        )
    })?;

    let mut devices = Vec::new();
    for id in device_ids {
        if !has_output_streams(id) {
            continue;
        }
        let name = device_name(id).unwrap_or_else(|_| format!("Unknown ({})", id));
        let sample_rates = available_sample_rates(id).unwrap_or_default();
        devices.push(AudioDevice {
            id,
            name,
            sample_rates,
        });
    }

    Ok(devices)
}

/// Check if a device has output streams.
fn has_output_streams(device_id: AudioDeviceID) -> bool {
    let property = AudioObjectPropertyAddress {
        mSelector: kAudioDevicePropertyStreams,
        mScope: kAudioObjectPropertyScopeOutput,
        mElement: kAudioObjectPropertyElementMain,
    };

    let mut size: u32 = 0;
    // SAFETY: Querying data size only — no output buffer, just writes to `size`.
    let status =
        unsafe { AudioObjectGetPropertyDataSize(device_id, &property, 0, ptr::null(), &mut size) };

    status == 0 && size > 0
}

/// Get a device's name via CFString.
fn device_name(device_id: AudioDeviceID) -> Result<String> {
    let property = AudioObjectPropertyAddress {
        mSelector: kAudioObjectPropertyName,
        mScope: kAudioObjectPropertyScopeGlobal,
        mElement: kAudioObjectPropertyElementMain,
    };

    let mut name_ref: CFStringRef = ptr::null();
    let mut size = mem::size_of::<CFStringRef>() as u32;

    // SAFETY: Standard CoreAudio property query. `name_ref` is a correctly-sized
    // output buffer for a single CFStringRef. CoreAudio writes the pointer and
    // transfers ownership to the caller (Create Rule).
    check(unsafe {
        AudioObjectGetPropertyData(
            device_id,
            &property,
            0,
            ptr::null(),
            &mut size,
            &mut name_ref as *mut _ as *mut _,
        )
    })?;

    if name_ref.is_null() {
        return Ok(String::new());
    }

    // SAFETY: `name_ref` was returned by a CoreAudio Create Rule API — the caller
    // owns the reference. `wrap_under_create_rule` takes ownership and will
    // CFRelease on drop, so no manual release is needed. The pointer cast bridges
    // coreaudio-sys's CFStringRef and core-foundation's CFStringRef which are
    // identical C types from different bindgen runs.
    let cf_string: CFString = unsafe {
        CFString::wrap_under_create_rule(name_ref as core_foundation::string::CFStringRef)
    };
    Ok(cf_string.to_string())
}

/// Get available sample rates for a device.
pub fn available_sample_rates(device_id: AudioDeviceID) -> Result<Vec<f64>> {
    let property = AudioObjectPropertyAddress {
        mSelector: kAudioDevicePropertyAvailableNominalSampleRates,
        mScope: kAudioObjectPropertyScopeOutput,
        mElement: kAudioObjectPropertyElementMain,
    };

    let mut size: u32 = 0;
    // SAFETY: Querying data size only — no output buffer, just writes to `size`.
    check(unsafe {
        AudioObjectGetPropertyDataSize(device_id, &property, 0, ptr::null(), &mut size)
    })?;

    let count = size as usize / mem::size_of::<AudioValueRange>();
    let mut ranges = vec![
        AudioValueRange {
            mMinimum: 0.0,
            mMaximum: 0.0,
        };
        count
    ];

    // SAFETY: `ranges` is pre-allocated to exactly the size returned by
    // GetPropertyDataSize. CoreAudio fills it with `count` AudioValueRange structs.
    check(unsafe {
        AudioObjectGetPropertyData(
            device_id,
            &property,
            0,
            ptr::null(),
            &mut size,
            ranges.as_mut_ptr() as *mut _,
        )
    })?;

    let mut rates: Vec<f64> = ranges.iter().map(|r| r.mMaximum).collect();
    rates.sort_by(|a, b| a.partial_cmp(b).unwrap_or(std::cmp::Ordering::Equal));
    rates.dedup();

    Ok(rates)
}

/// Get the current nominal sample rate of a device.
pub fn get_device_sample_rate(device_id: AudioDeviceID) -> Result<f64> {
    let property = AudioObjectPropertyAddress {
        mSelector: kAudioDevicePropertyNominalSampleRate,
        mScope: kAudioObjectPropertyScopeGlobal,
        mElement: kAudioObjectPropertyElementMain,
    };

    let mut rate: f64 = 0.0;
    let mut size = mem::size_of::<f64>() as u32;

    // SAFETY: `rate` is a stack-allocated f64 with correct size for the property.
    check(unsafe {
        AudioObjectGetPropertyData(
            device_id,
            &property,
            0,
            ptr::null(),
            &mut size,
            &mut rate as *mut _ as *mut _,
        )
    })?;

    Ok(rate)
}

/// Find an output device by name. Returns the device ID if found.
pub fn find_output_device_by_name(name: &str) -> Result<AudioDeviceID> {
    let devices = list_output_devices()?;
    devices
        .iter()
        .find(|d| d.name == name)
        .map(|d| d.id)
        .ok_or_else(|| DeviceError::NotFoundByName(name.to_string()))
}

/// Set the nominal sample rate of a device (for bit-perfect matching).
pub fn set_device_sample_rate(device_id: AudioDeviceID, rate: f64) -> Result<()> {
    let property = AudioObjectPropertyAddress {
        mSelector: kAudioDevicePropertyNominalSampleRate,
        mScope: kAudioObjectPropertyScopeGlobal,
        mElement: kAudioObjectPropertyElementMain,
    };

    // SAFETY: `rate` is a stack-allocated f64 with correct size for the property.
    check(unsafe {
        AudioObjectSetPropertyData(
            device_id,
            &property,
            0,
            ptr::null(),
            mem::size_of::<f64>() as u32,
            &rate as *const _ as *const _,
        )
    })
}