//! Media Processing Pipeline (N-05)
//!
//! Applies dynamic WASM-based transforms (e.g., background blur, noise cancellation)
//! to media streams in flight without breaking the SFU isolation boundary.

use crate::edge_wasm::EdgeWasmEngine;
use crate::sfu::ForwardPacket;
use std::sync::Arc;
use tokio::sync::RwLock;
use tracing::{debug, info, warn};

/// A configured media processing pipeline for a specific stream.
pub struct MediaPipeline {
    engine: Arc<EdgeWasmEngine>,
    active_transforms: Arc<RwLock<Vec<wasmtime::Module>>>,
}

impl MediaPipeline {
    pub fn new(engine: Arc<EdgeWasmEngine>) -> Self {
        info!("[Media] Initializing edge media transformation pipeline");
        Self {
            engine,
            active_transforms: Arc::new(RwLock::new(Vec::new())),
        }
    }

    /// Load the background blur WASM kernel into the pipeline
    pub async fn enable_background_blur(&self) -> Result<(), anyhow::Error> {
        info!("[Media] Loading Background Blur (ML) WASM transform...");

        // Mock WAT module for background blur simulation
        // In reality this would be a WebAssembly module containing an ONNX runner or OpenCV routines
        let wat = r#"
        (module
            (memory (export "memory") 1)
            (func (export "alloc") (param $size i32) (result i32)
                (i32.const 0)
            )
            (func (export "transform") (param $ptr i32) (param $len i32) (result i32)
                ;; Simulate blur by shifting bytes (just a mock structural change for the payload)
                (local.get $len)
            )
        )
        "#;

        let wasm_bytes = wat::parse_str(wat)?;
        let module = self.engine.load_module(&wasm_bytes)?;

        self.active_transforms.write().await.push(module);
        info!("[Media] Background blur transform engaged.");
        Ok(())
    }

    /// Load the noise cancellation WASM kernel into the pipeline
    pub async fn enable_noise_cancellation(&self) -> Result<(), anyhow::Error> {
        info!("[Media] Loading Noise Cancellation (DSP) WASM transform...");

        let wat = r#"
        (module
            (memory (export "memory") 1)
            (func (export "alloc") (param $size i32) (result i32)
                (i32.const 0)
            )
            (func (export "transform") (param $ptr i32) (param $len i32) (result i32)
                ;; Simulate audio denoising
                (local.get $len)
            )
        )
        "#;

        let wasm_bytes = wat::parse_str(wat)?;
        let module = self.engine.load_module(&wasm_bytes)?;

        self.active_transforms.write().await.push(module);
        info!("[Media] Noise cancellation transform engaged.");
        Ok(())
    }

    /// Process a packet sequentially through all active WASM edge transforms.
    /// This is where the actual CPU-bound in-flight manipulation occurs.
    pub async fn process_frame(
        &self,
        mut packet: ForwardPacket,
    ) -> Result<ForwardPacket, anyhow::Error> {
        let transforms = self.active_transforms.read().await;

        if transforms.is_empty() {
            return Ok(packet);
        }

        debug!(
            "[Media] Applying {} transforms to stream {}",
            transforms.len(),
            packet.stream_id
        );

        for module in transforms.iter() {
            self.engine.process_packet(module, &mut packet)?;
        }

        Ok(packet)
    }
}
