//! Constants affecting driver function and API handling.

#[cfg(feature = "driver")]
use audiopus::{Bitrate, SampleRate};
#[cfg(feature = "driver")]
use discortp::rtp::RtpType;
use std::time::Duration;

#[cfg(feature = "driver")]
/// The voice gateway version used by the library.
pub const VOICE_GATEWAY_VERSION: u8 = crate::model::constants::GATEWAY_VERSION;

#[cfg(feature = "driver")]
/// Sample rate of audio to be sent to Discord.
pub const SAMPLE_RATE: SampleRate = SampleRate::Hz48000;

/// Sample rate of audio to be sent to Discord.
pub const SAMPLE_RATE_RAW: usize = 48_000;

/// Number of audio frames/packets to be sent per second.
pub const AUDIO_FRAME_RATE: usize = 50;

/// Length of time between any two audio frames.
pub const TIMESTEP_LENGTH: Duration = Duration::from_millis(1000 / AUDIO_FRAME_RATE as u64);

#[cfg(feature = "driver")]
/// Default bitrate for audio.
pub const DEFAULT_BITRATE: Bitrate = Bitrate::BitsPerSecond(128_000);

/// Number of samples in one complete frame of audio per channel.
///
/// This is equally the number of stereo (joint) samples in an audio frame.
pub const MONO_FRAME_SIZE: usize = SAMPLE_RATE_RAW / AUDIO_FRAME_RATE;

/// Number of individual samples in one complete frame of stereo audio.
pub const STEREO_FRAME_SIZE: usize = 2 * MONO_FRAME_SIZE;

/// Number of bytes in one complete frame of raw `f32`-encoded mono audio.
pub const MONO_FRAME_BYTE_SIZE: usize = MONO_FRAME_SIZE * std::mem::size_of::<f32>();

/// Number of bytes in one complete frame of raw `f32`-encoded stereo audio.
pub const STEREO_FRAME_BYTE_SIZE: usize = STEREO_FRAME_SIZE * std::mem::size_of::<f32>();

/// Length (in milliseconds) of any audio frame.
pub const FRAME_LEN_MS: usize = 1000 / AUDIO_FRAME_RATE;

/// Maximum number of audio frames/packets to be sent per second to be buffered.
pub const CHILD_BUFFER_LEN: usize = AUDIO_FRAME_RATE / 2;

/// Maximum packet size for a voice packet.
///
/// Set a safe amount below the Ethernet MTU to avoid fragmentation/rejection.
pub const VOICE_PACKET_MAX: usize = 1460;

/// Delay between sends of UDP keepalive frames.
///
/// Passive monitoring of Discord itself shows that these fire every 5 seconds
/// irrespective of outgoing UDP traffic.
pub const UDP_KEEPALIVE_GAP_MS: u64 = 5_000;

/// Type-converted delay between sends of UDP keepalive frames.
///
/// Passive monitoring of Discord itself shows that these fire every 5 seconds
/// irrespective of outgoing UDP traffic.
pub const UDP_KEEPALIVE_GAP: Duration = Duration::from_millis(UDP_KEEPALIVE_GAP_MS);

/// Opus silent frame, used to signal speech start and end (and prevent audio glitching).
pub const SILENT_FRAME: [u8; 3] = [0xf8, 0xff, 0xfe];

/// The one (and only) RTP version.
pub const RTP_VERSION: u8 = 2;

#[cfg(feature = "driver")]
/// Profile type used by Discord's Opus audio traffic.
pub const RTP_PROFILE_TYPE: RtpType = RtpType::Dynamic(120);