gst-flexhlssink-rs/src/imp.rs

use glib::subclass::prelude::*;
use gst::prelude::*;
use gst::subclass::prelude::*;
use gst::{gst_debug, gst_error, gst_info};

use crate::playlist::PlaylistRenderState;
use m3u8_rs::playlist::{MediaPlaylist, MediaPlaylistType, MediaSegment};
use once_cell::sync::Lazy;
use std::fs::{File, OpenOptions};
use std::io::Write;
use std::path;
use std::sync::{Arc, Mutex, MutexGuard};

const DEFAULT_LOCATION: &str = "segment%05d.ts";
const DEFAULT_PLAYLIST_LOCATION: &str = "playlist.m3u8";
const DEFAULT_MAX_FILES: u32 = 10;
const DEFAULT_TARGET_DURATION: u32 = 15;
const DEFAULT_PLAYLIST_LENGTH: u32 = 5;
const DEFAULT_SEND_KEYFRAME_REQUESTS: bool = true;

const GST_M3U8_PLAYLIST_VERSION: usize = 3;
const BACKWARDS_COMPATIBLE_PLACEHOLDER: &str = "%05d";

static CAT: Lazy<gst::DebugCategory> = Lazy::new(|| {
    gst::DebugCategory::new(
        "flexhlssink",
        gst::DebugColorFlags::empty(),
        Some("Flexible HLS sink"),
    )
});

struct Settings {
    location: String,
    playlist_location: String, // TODO: Evaluate the use of `PathBuf` instead.
    playlist_root: Option<String>, // TODO: Evaluate the use of `PathBuf` instead.
    playlist_length: u32,
    max_files: u32,
    target_duration: u32,
    send_keyframe_requests: bool,

    // TODO: old_locations ? Maybe just use another thread and send msgs with files to delete ?
    splitmuxsink: Option<gst::Element>,
    app_sink: Option<gst::Element>,
    muxer: Option<gst::Element>,
    video_sink: bool,
    audio_sink: bool,
}

impl Default for Settings {
    fn default() -> Self {
        Self {
            location: String::from(DEFAULT_LOCATION),
            playlist_location: String::from(DEFAULT_PLAYLIST_LOCATION),
            playlist_root: None,
            playlist_length: DEFAULT_PLAYLIST_LENGTH,
            max_files: DEFAULT_MAX_FILES,
            target_duration: DEFAULT_TARGET_DURATION,
            send_keyframe_requests: DEFAULT_SEND_KEYFRAME_REQUESTS,

            splitmuxsink: None,
            app_sink: None,
            muxer: None,
            video_sink: false,
            audio_sink: false,
        }
    }
}

enum State {
    Stopped,
    Started {
        playlist: MediaPlaylist,
        playlist_render_state: PlaylistRenderState,
        playlist_index: u32,

        current_segment_file: Option<File>,
        current_running_time_start: Option<gst::ClockTime>,
        current_segment_location: Option<String>,
    },
}

impl Default for State {
    fn default() -> Self {
        Self::Stopped
    }
}

#[derive(Default, Clone)]
pub struct FlexHlsSink {
    settings: Arc<Mutex<Settings>>,
    state: Arc<Mutex<State>>,
}

impl FlexHlsSink {
    fn new() -> Self {
        Self {
            settings: Arc::new(Mutex::new(Settings::default())),
            state: Arc::new(Mutex::new(State::default())),
        }
    }

    fn on_format_location(&self, fragment_id: u32) -> Result<(), String> {
        let mut state = self.state.lock().unwrap();
        let (current_segment_location, current_segment_file) = match &mut *state {
            State::Stopped => return Err("Not in Started state".to_string()),
            State::Started {
                current_segment_location,
                current_segment_file,
                ..
            } => (current_segment_location, current_segment_file),
        };

        let settings = self.settings.lock().unwrap();

        let seq_num = format!("{:0>5}", fragment_id);
        let segment_file_location = settings
            .location
            .replace(BACKWARDS_COMPATIBLE_PLACEHOLDER, &seq_num);

        let segment_file_location_clone = segment_file_location.clone();
        let segment_file = File::create(&segment_file_location).map_err(move |err| {
            gst_error!(
                CAT,
                "Could not create a new segment file: {}",
                segment_file_location_clone
            );
            err.to_string()
        })?;

        *current_segment_location = Some(segment_file_location);
        *current_segment_file = Some(segment_file);

        gst_debug!(
            CAT,
            "New segment location: {}",
            current_segment_location.as_ref().unwrap()
        );
        Ok(())
    }

    fn start(
        &self,
        element: &super::FlexHlsSink,
    ) -> Result<gst::StateChangeSuccess, gst::StateChangeError> {
        gst_debug!(CAT, obj: element, "Starting");

        let settings = self.settings.lock().unwrap();
        let mut state = self.state.lock().unwrap();
        if let State::Stopped = *state {
            *state = State::Started {
                playlist: MediaPlaylist {
                    version: GST_M3U8_PLAYLIST_VERSION,
                    target_duration: settings.target_duration as f32,
                    media_sequence: 0,
                    segments: vec![],
                    discontinuity_sequence: 0,
                    end_list: false,
                    playlist_type: Some(MediaPlaylistType::Event),
                    i_frames_only: false,
                    start: None,
                    independent_segments: false,
                    unknown_tags: vec![],
                },
                playlist_render_state: PlaylistRenderState::Init,
                playlist_index: 0,
                current_segment_location: None,
                current_running_time_start: None,
                current_segment_file: None,
            };
        }

        Ok(gst::StateChangeSuccess::Success)
    }

    fn stop(&self, element: &super::FlexHlsSink) {
        gst_debug!(CAT, obj: element, "Stopping");

        let mut state = self.state.lock().unwrap();
        if let State::Started { .. } = *state {
            *state = State::Stopped;
        }

        gst_debug!(CAT, obj: element, "Stopped");
    }

    fn write_playlist(
        &self,
        element: &super::FlexHlsSink,
        fragment_closed_at: gst::ClockTime,
    ) -> Result<gst::StateChangeSuccess, gst::StateChangeError> {
        gst_debug!(CAT, obj: element, "Preparing to write new playlist");

        let mut state = self.state.lock().unwrap();
        match &mut *state {
            State::Stopped => {}
            State::Started {
                current_running_time_start,
                playlist,
                current_segment_location,
                playlist_render_state: render_state,
                ..
            } => {
                gst_info!(CAT, "COUNT {}", playlist.segments.len());
                // TODO: Add new entry to the playlist

                let segment_location = current_segment_location
                    .as_ref()
                    .ok_or_else(|| gst::StateChangeError)?;

                let segment_duration =
                    fragment_closed_at - current_running_time_start.as_ref().unwrap();

                playlist.segments.push(MediaSegment {
                    uri: segment_location.to_string(),
                    duration: segment_duration.seconds().unwrap() as f32,
                    title: None,
                    byte_range: None,
                    discontinuity: false,
                    key: None,
                    map: None,
                    program_date_time: None,
                    daterange: None,
                });

                // TODO: Write playlist to fs
                let settings = self.settings.lock().unwrap();
                let playlist_location = settings.playlist_location.clone();

                let element_weak = element.downgrade();
                let mut playlist_file = OpenOptions::new()
                    .write(true)
                    .create(true)
                    .open(playlist_location.clone())
                    .map_err(move |err| {
                        let error_msg = gst::error_msg!(
                            gst::ResourceError::OpenWrite,
                            [
                                "Could not open playlist file {} for writing: {}",
                                playlist_location,
                                err.to_string(),
                            ]
                        );
                        let element = element_weak.upgrade().unwrap();
                        element.post_error_message(error_msg);

                        gst::StateChangeError
                    })?;

                playlist.write_to(&mut playlist_file).map_err(|err| {
                    gst_error!(
                        CAT,
                        "Could not write new playlist file: {}",
                        err.to_string()
                    );
                    gst::StateChangeError
                })?;

                // TODO: clean up (delete) old segment files
                *render_state = PlaylistRenderState::Started;
                *current_segment_location = None;
            }
        };

        gst_debug!(CAT, obj: element, "Wrote new playlist file!");
        Ok(gst::StateChangeSuccess::Success)
    }

    fn write_final_playlist(
        &self,
        element: &super::FlexHlsSink,
    ) -> Result<gst::StateChangeSuccess, gst::StateChangeError> {
        gst_debug!(CAT, obj: element, "Preparing to write final playlist");

        Ok(self.write_playlist(element, element.current_running_time())?)
    }
}

#[glib::object_subclass]
impl ObjectSubclass for FlexHlsSink {
    const NAME: &'static str = "FlexHlsSink";
    type Type = super::FlexHlsSink;
    type ParentType = gst::Bin;

    fn with_class(_klass: &Self::Class) -> Self {
        Self::new()
    }
}

impl BinImpl for FlexHlsSink {
    #[allow(clippy::single_match)]
    fn handle_message(&self, element: &Self::Type, msg: gst::Message) {
        use gst::MessageView;

        match msg.view() {
            MessageView::Element(ref msg) => {
                let settings = self.settings.lock().unwrap();

                if settings.splitmuxsink.is_some()
                    && msg.src().as_ref()
                        == Some(settings.splitmuxsink.as_ref().unwrap().upcast_ref())
                {
                    let s = msg.structure().unwrap();
                    if msg
                        .structure()
                        .map(|s| s.name() == "splitmuxsink-fragment-opened")
                        .unwrap_or(false)
                    {
                        if let Ok(fragment_opened_at) = s.get::<gst::ClockTime>("running-time") {
                            let mut state = self.state.lock().unwrap();
                            match &mut *state {
                                State::Stopped => return,
                                State::Started {
                                    current_running_time_start,
                                    ..
                                } => *current_running_time_start = Some(fragment_opened_at),
                            };
                        }
                    }
                    if msg
                        .structure()
                        .map(|s| s.name() == "splitmuxsink-fragment-closed")
                        .unwrap_or(false)
                    {
                        let s = msg.structure().unwrap();
                        if let Ok(fragment_closed_at) = s.get::<gst::ClockTime>("running-time") {
                            self.write_playlist(element, fragment_closed_at).unwrap();
                        }
                    }
                }
            }
            _ => self.parent_handle_message(element, msg),
        }
    }
}

impl ObjectImpl for FlexHlsSink {
    fn properties() -> &'static [glib::ParamSpec] {
        static PROPERTIES: Lazy<Vec<glib::ParamSpec>> = Lazy::new(|| {
            vec![
                glib::ParamSpec::new_string(
                    "location",
                    "File Location",
                    "Location of the file to write",
                    Some(DEFAULT_LOCATION),
                    glib::ParamFlags::READWRITE,
                ),
                glib::ParamSpec::new_string(
                    "playlist-location",
                    "Playlist Location",
                    "Location of the playlist to write.",
                    Some(DEFAULT_PLAYLIST_LOCATION),
                    glib::ParamFlags::READWRITE,
                ),
                glib::ParamSpec::new_string(
                    "playlist-root",
                    "Playlist Root",
                    "Location of the playlist to write.",
                    None,
                    glib::ParamFlags::READWRITE,
                ),
                glib::ParamSpec::new_uint(
                    "max-files",
                    "Max files",
                    "Maximum number of files to keep on disk. Once the maximum is reached, old files start to be deleted to make room for new ones.",
                    0,
                    u32::MAX,
                    DEFAULT_MAX_FILES,
                    glib::ParamFlags::READWRITE,
                ),
                glib::ParamSpec::new_uint(
                    "target-duration",
                    "Target duration",
                    "The target duration in seconds of a segment/file. (0 - disabled, useful for management of segment duration by the streaming server)",
                    0,
                    u32::MAX,
                    DEFAULT_TARGET_DURATION,
                    glib::ParamFlags::READWRITE,
                ),
                glib::ParamSpec::new_uint(
                    "playlist-length",
                    "Playlist length",
                    "Length of HLS playlist. To allow players to conform to section 6.3.3 of the HLS specification, this should be at least 3. If set to 0, the playlist will be infinite.",
                    0,
                    u32::MAX,
                    DEFAULT_PLAYLIST_LENGTH,
                    glib::ParamFlags::READWRITE,
                ),
                glib::ParamSpec::new_boolean(
                    "send-keyframe-requests",
                    "Send Keyframe Requests",
                    "Send keyframe requests to ensure correct fragmentation. If this is disabled then the input must have keyframes in regular intervals.",
                    DEFAULT_SEND_KEYFRAME_REQUESTS,
                    glib::ParamFlags::READWRITE,
                ),
            ]
        });

        PROPERTIES.as_ref()
    }

    fn set_property(
        &self,
        _obj: &Self::Type,
        _id: usize,
        value: &glib::Value,
        pspec: &glib::ParamSpec,
    ) {
        let mut settings = self.settings.lock().unwrap();
        match pspec.name() {
            "location" => {
                settings.location = value
                    .get::<Option<String>>()
                    .expect("type checked upstream")
                    .unwrap_or_else(|| DEFAULT_LOCATION.into());
                if let Some(splitmuxsink) = &settings.splitmuxsink {
                    splitmuxsink
                        .set_property("location", &settings.location)
                        .unwrap();
                }
            }
            "playlist-location" => {
                settings.playlist_location = value
                    .get::<Option<String>>()
                    .expect("type checked upstream")
                    .unwrap_or_else(|| DEFAULT_LOCATION.into());
            }
            "playlist-root" => {
                settings.playlist_root = value
                    .get::<Option<String>>()
                    .expect("type checked upstream");
            }
            "max-files" => {
                settings.max_files = value.get().expect("type checked upstream");
            }
            "target-duration" => {
                settings.target_duration = value.get().expect("type checked upstream");
                if let Some(splitmuxsink) = &settings.splitmuxsink {
                    splitmuxsink
                        .set_property(
                            "max-size-time",
                            &((settings.target_duration as u64) * gst::SECOND_VAL),
                        )
                        .unwrap();
                }
            }
            "playlist-length" => {
                settings.playlist_length = value.get().expect("type checked upstream");
            }
            "send-keyframe-requests" => {
                settings.send_keyframe_requests = value.get().expect("type checked upstream");
                if let Some(splitmuxsink) = &settings.splitmuxsink {
                    splitmuxsink
                        .set_property("send-keyframe-requests", &settings.send_keyframe_requests)
                        .unwrap();
                }
            }
            _ => unimplemented!(),
        };
    }

    fn property(&self, _obj: &Self::Type, _id: usize, pspec: &glib::ParamSpec) -> glib::Value {
        let settings = self.settings.lock().unwrap();
        match pspec.name() {
            "location" => settings.location.to_value(),
            "playlist-location" => settings.playlist_location.to_value(),
            "playlist-root" => settings.playlist_root.to_value(),
            "max-files" => settings.max_files.to_value(),
            "target-duration" => settings.target_duration.to_value(),
            "playlist-length" => settings.playlist_length.to_value(),
            "send-keyframe-requests" => settings.send_keyframe_requests.to_value(),
            _ => unimplemented!(),
        }
    }

    // Called right after construction of a new instance
    fn constructed(&self, obj: &Self::Type) {
        // Call the parent class' ::constructed() implementation first
        self.parent_constructed(obj);

        let mut settings = self.settings.lock().unwrap();

        let splitmuxsink = gst::ElementFactory::make("splitmuxsink", Some("split_mux_sink"))
            .expect("Could not make element splitmuxsink");
        let app_sink = gst::ElementFactory::make("appsink", Some("app_sink"))
            .expect("Could not make element appsink");
        let mux = gst::ElementFactory::make("mpegtsmux", Some("mpeg-ts_mux"))
            .expect("Could not make element mpegtsmux");

        let location: Option<String> = None;
        splitmuxsink
            .set_properties(&[
                ("location", &location),
                (
                    "max-size-time",
                    &((settings.target_duration as u64) * gst::SECOND_VAL),
                ),
                ("send-keyframe-requests", &true),
                ("muxer", &mux),
                ("sink", &app_sink),
                ("reset-muxer", &false),
            ])
            .unwrap();

        obj.add(&splitmuxsink).unwrap();
        obj.set_element_flags(gst::ElementFlags::SINK);

        let this = self.clone();
        splitmuxsink
            .connect("format-location", false, move |args| {
                let fragment_id = args[1].get::<u32>().unwrap();

                if let Err(err) = this.on_format_location(fragment_id) {
                    gst_error!(CAT, "on format-location handler: {}", err);
                }
                None
            })
            .unwrap();

        let sink = app_sink.downcast_ref::<gst_app::AppSink>().unwrap();
        let this = self.clone();
        let element_weak = obj.downgrade();
        sink.set_callbacks(
            gst_app::AppSinkCallbacks::builder()
                .new_sample(move |app_sink| {
                    let sample = app_sink.pull_sample().map_err(|_| gst::FlowError::Eos)?;
                    let buffer = sample.buffer().ok_or(gst::FlowError::Error)?;

                    let mut state = this.state.lock().unwrap();
                    let (current_segment_file, current_segment_location) = match &mut *state {
                        State::Stopped => return Err(gst::FlowError::Error),
                        State::Started {
                            current_segment_file,
                            current_segment_location,
                            ..
                        } => (current_segment_file, current_segment_location),
                    };

                    if let (Some(segment_file), Some(segment_location)) =
                        (current_segment_file, current_segment_location)
                    {
                        let segment_location = segment_location.clone();
                        let data = buffer.map_readable().unwrap();
                        segment_file.write(&data).map_err(|err| {
                            let error_msg = gst::error_msg!(
                                gst::ResourceError::OpenWrite,
                                [
                                    "Could not write to segment file \"{}\": {}",
                                    segment_location,
                                    err.to_string(),
                                ]
                            );
                            let element = element_weak.upgrade().unwrap();
                            element.post_error_message(error_msg);

                            gst::FlowError::Error
                        })?;
                    }

                    Ok(gst::FlowSuccess::Ok)
                })
                .build(),
        );

        settings.splitmuxsink = Some(splitmuxsink);
        settings.app_sink = Some(app_sink);
        settings.muxer = Some(mux);
    }
}

impl ElementImpl for FlexHlsSink {
    fn metadata() -> Option<&'static gst::subclass::ElementMetadata> {
        static ELEMENT_METADATA: Lazy<gst::subclass::ElementMetadata> = Lazy::new(|| {
            gst::subclass::ElementMetadata::new(
                "Flexible HTTP Live Streaming sink",
                "Sink/Muxer",
                "Flexible HTTP Live Streaming sink",
                "Alessandro Decina <alessandro.d@gmail.com>, Sebastian Dröge <sebastian@centricular.com>, Rafael Caricio <rafael@caricio.com>",
            )
        });

        Some(&*ELEMENT_METADATA)
    }

    fn pad_templates() -> &'static [gst::PadTemplate] {
        static PAD_TEMPLATES: Lazy<Vec<gst::PadTemplate>> = Lazy::new(|| {
            let caps = gst::Caps::new_any();
            let video_pad_template = gst::PadTemplate::new(
                "video",
                gst::PadDirection::Sink,
                gst::PadPresence::Request,
                &caps,
            )
            .unwrap();

            let caps = gst::Caps::new_any();
            let audio_pad_template = gst::PadTemplate::new(
                "audio",
                gst::PadDirection::Sink,
                gst::PadPresence::Request,
                &caps,
            )
            .unwrap();

            vec![video_pad_template, audio_pad_template]
        });

        PAD_TEMPLATES.as_ref()
    }

    fn change_state(
        &self,
        element: &Self::Type,
        transition: gst::StateChange,
    ) -> Result<gst::StateChangeSuccess, gst::StateChangeError> {
        match transition {
            gst::StateChange::NullToReady => {
                self.start(element)?;
            }
            _ => (),
        }

        self.parent_change_state(element, transition)?;

        match transition {
            gst::StateChange::PausedToReady => {
                self.write_final_playlist(element)?;
            }
            gst::StateChange::ReadyToNull => {
                self.stop(element);
            }
            _ => (),
        }

        Ok(gst::StateChangeSuccess::Success)
    }

    fn request_new_pad(
        &self,
        element: &Self::Type,
        templ: &gst::PadTemplate,
        name: Option<String>,
        caps: Option<&gst::Caps>,
    ) -> Option<gst::Pad> {
        let mut settings = self.settings.lock().unwrap();
        match name.as_ref().map(|val| val.as_str()) {
            Some("audio") => {
                if settings.audio_sink {
                    gst_debug!(
                        CAT,
                        obj: element,
                        "requested_new_pad: audio pad is already set"
                    );
                    return None;
                }
                gst_info!(CAT, "creating the audio pad");

                let splitmuxsink = match &mut settings.splitmuxsink {
                    None => return None,
                    Some(sms) => sms,
                };
                let peer_pad = splitmuxsink.request_pad_simple("audio_0").unwrap();
                println!("Peer pad caps: {:?}", peer_pad.allowed_caps());
                let sink_pad = gst::GhostPad::from_template_with_target(&templ, Some("audio"), &peer_pad).unwrap();
                sink_pad.set_active(true).unwrap();
                element.add_pad(&sink_pad).unwrap();
                settings.audio_sink = true;

                Some(sink_pad.upcast())
            }
            Some("video") => {
                if settings.video_sink {
                    gst_debug!(
                        CAT,
                        obj: element,
                        "requested_new_pad: video pad is already set"
                    );
                    return None;
                }
                let peer_pad_name = "video";
                let pad_name = "video";

                let splitmuxsink = match &mut settings.splitmuxsink {
                    None => return None,
                    Some(sms) => sms,
                };
                let peer_pad = match splitmuxsink.request_pad_simple(peer_pad_name) {
                    None => return None,
                    Some(pad) => pad,
                };
                let sink_pad = gst::GhostPad::from_template_with_target(&templ, Some(pad_name), &peer_pad).unwrap();
                sink_pad.set_active(true).unwrap();

                element.add_pad(&sink_pad).unwrap();
                settings.video_sink = true;

                Some(sink_pad.upcast())
            }
            None => None,
            Some(other_name) => {
                gst_debug!(
                    CAT,
                    obj: element,
                    "requested_new_pad: name \"{}\" is not audio or video",
                    other_name
                );
                None
            }
        }
    }

    fn release_pad(&self, element: &Self::Type, pad: &gst::Pad) {
        let mut settings = self.settings.lock().unwrap();

        if !settings.audio_sink && !settings.video_sink {
            return;
        }

        settings
            .splitmuxsink
            .as_ref()
            .unwrap()
            .release_request_pad(pad);
        element.remove_pad(pad).unwrap();
        pad.set_active(false).unwrap();

        let ghost_pad = pad.downcast_ref::<gst::GhostPad>().unwrap();
        if "audio" == ghost_pad.name() {
            settings.audio_sink = false;
        } else {
            settings.video_sink = false;
        }
    }
}