// file: src/media_audio.rs

use crate::app_state::AppState;
use crate::error::AppError;
use gstreamer as gst;
use gst::prelude::*;

fn build_output_dir() -> Result<std::path::PathBuf, AppError> {
    let app_data_dir = dirs::data_local_dir();

    let Some(mut base_dir) = app_data_dir else {
        return Err(AppError::Io("unable to resolve local data directory".to_string()));
    };

    base_dir.push("tauri-video01");
    base_dir.push("records");

    let create_dir_result = std::fs::create_dir_all(&base_dir);
    if let Err(error) = create_dir_result {
        return Err(AppError::Io(format!(
            "unable to create output directory '{}': {error}",
            base_dir.display()
        )));
    }

    Ok(base_dir)
}

fn build_output_path() -> Result<std::path::PathBuf, AppError> {
    let mut dir = build_output_dir()?;
    let timestamp = chrono::Local::now().format("%Y%m%d-%H%M%S").to_string();
    dir.push(format!("audio-{timestamp}.wav"));
    Ok(dir)
}

fn build_pipeline(output_path: &std::path::Path) -> Result<gst::Pipeline, AppError> {
    let location = output_path.to_string_lossy().replace('\\', "\\\\").replace('"', "\\\"");
    let pipeline_str = format!(
        "autoaudiosrc ! audioconvert ! audioresample ! wavenc ! filesink location=\"{location}\""
    );

    tracing::info!(pipeline = %pipeline_str, "building audio pipeline");

    let element_result = gst::parse::launch(&pipeline_str);
    let element = match element_result {
        Ok(value) => value,
        Err(error) => {
            return Err(AppError::Gst(format!(
                "unable to parse pipeline: {error}"
            )));
        }
    };

    let downcast_result = element.downcast::<gst::Pipeline>();
    match downcast_result {
        Ok(pipeline) => Ok(pipeline),
        Err(_) => Err(AppError::Gst(
            "parsed element is not a pipeline".to_string(),
        )),
    }
}

pub fn start_audio_recording(state: &tauri::State<'_, AppState>) -> Result<String, AppError> {
    let mut guard = match state.audio.lock() {
        Ok(value) => value,
        Err(_) => {
            return Err(AppError::State(
                "audio state lock poisoned".to_string(),
            ));
        }
    };

    if guard.is_recording {
        return Err(AppError::State(
            "audio recording is already running".to_string(),
        ));
    }

    let output_path = build_output_path()?;
    let pipeline = build_pipeline(&output_path)?;

    let set_state_result = pipeline.set_state(gst::State::Playing);
    match set_state_result {
        Ok(_) => {}
        Err(error) => {
            return Err(AppError::Gst(format!(
                "unable to set pipeline to playing: {error:?}"
            )));
        }
    }

    tracing::info!(path = %output_path.display(), "audio recording started");

    guard.is_recording = true;
    guard.output_path = Some(output_path.clone());
    guard.pipeline = Some(pipeline);

    Ok(output_path.display().to_string())
}

pub fn stop_audio_recording(state: &tauri::State<'_, AppState>) -> Result<String, AppError> {
    let mut guard = match state.audio.lock() {
        Ok(value) => value,
        Err(_) => {
            return Err(AppError::State(
                "audio state lock poisoned".to_string(),
            ));
        }
    };

    if !guard.is_recording {
        return Err(AppError::State(
            "audio recording is not running".to_string(),
        ));
    }

    let pipeline = match guard.pipeline.take() {
        Some(value) => value,
        None => {
            return Err(AppError::State(
                "missing pipeline while recording flag is set".to_string(),
            ));
        }
    };

    let output_path = match guard.output_path.clone() {
        Some(value) => value,
        None => {
            return Err(AppError::State(
                "missing output path while recording flag is set".to_string(),
            ));
        }
    };

    let send_event_result = pipeline.send_event(gst::event::Eos::new());
    if !send_event_result {
        tracing::warn!("failed to send EOS event to pipeline");
    }

    let bus = pipeline.bus();
    if let Some(bus_ref) = bus {
        let _ = bus_ref.timed_pop_filtered(
            gst::ClockTime::from_seconds(5),
            &[gst::MessageType::Eos, gst::MessageType::Error],
        );
    }

    let set_state_result = pipeline.set_state(gst::State::Null);
    match set_state_result {
        Ok(_) => {}
        Err(error) => {
            return Err(AppError::Gst(format!(
                "unable to set pipeline to null: {error:?}"
            )));
        }
    }

    tracing::info!(path = %output_path.display(), "audio recording stopped");

    guard.is_recording = false;
    guard.output_path = None;
    guard.pipeline = None;

    Ok(output_path.display().to_string())
}