//! Ultra-low-latency WASM bindings for Lean Agentic Learning System
//!
//! Features:
//! - WebSocket streaming with minimal overhead
//! - SSE (Server-Sent Events) support
//! - HTTP streaming
//! - Zero-copy message passing where possible
//! - Optimized for latency (<1ms overhead)

use wasm_bindgen::prelude::*;
use wasm_bindgen::JsCast;
use wasm_bindgen_futures::JsFuture;
use web_sys::{WebSocket, EventSource, MessageEvent, CloseEvent, ErrorEvent};
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use std::cell::RefCell;
use std::rc::Rc;

// Use wee_alloc for smaller binary size
#[cfg(feature = "wee_alloc")]
#[global_allocator]
static ALLOC: wee_alloc::WeeAlloc = wee_alloc::WeeAlloc::INIT;

/// Initialize panic hook for better error messages
#[wasm_bindgen(start)]
pub fn init() {
    #[cfg(feature = "console_error_panic_hook")]
    console_error_panic_hook::set_once();
}

/// Configuration for the lean agentic system
#[wasm_bindgen]
#[derive(Clone, Serialize, Deserialize)]
pub struct LeanAgenticConfig {
    #[wasm_bindgen(skip)]
    pub enable_formal_verification: bool,

    #[wasm_bindgen(skip)]
    pub learning_rate: f64,

    #[wasm_bindgen(skip)]
    pub max_planning_depth: usize,

    #[wasm_bindgen(skip)]
    pub action_threshold: f64,
}

#[wasm_bindgen]
impl LeanAgenticConfig {
    #[wasm_bindgen(constructor)]
    pub fn new() -> Self {
        Self {
            enable_formal_verification: true,
            learning_rate: 0.01,
            max_planning_depth: 5,
            action_threshold: 0.7,
        }
    }

    #[wasm_bindgen(getter)]
    pub fn enable_formal_verification(&self) -> bool {
        self.enable_formal_verification
    }

    #[wasm_bindgen(setter)]
    pub fn set_enable_formal_verification(&mut self, value: bool) {
        self.enable_formal_verification = value;
    }

    #[wasm_bindgen(getter)]
    pub fn learning_rate(&self) -> f64 {
        self.learning_rate
    }

    #[wasm_bindgen(setter)]
    pub fn set_learning_rate(&mut self, value: f64) {
        self.learning_rate = value;
    }
}

impl Default for LeanAgenticConfig {
    fn default() -> Self {
        Self::new()
    }
}

/// Processing result
#[wasm_bindgen]
#[derive(Clone, Serialize, Deserialize)]
pub struct ProcessingResult {
    pub action: String,
    pub reward: f64,
    pub verified: bool,
    #[wasm_bindgen(skip)]
    pub timestamp: f64,
}

#[wasm_bindgen]
impl ProcessingResult {
    #[wasm_bindgen(getter)]
    pub fn timestamp(&self) -> f64 {
        self.timestamp
    }
}

/// WebSocket client for ultra-low-latency streaming
#[wasm_bindgen]
pub struct WebSocketClient {
    socket: WebSocket,
    #[wasm_bindgen(skip)]
    on_message: Rc<RefCell<Option<js_sys::Function>>>,
    #[wasm_bindgen(skip)]
    on_error: Rc<RefCell<Option<js_sys::Function>>>,
    #[wasm_bindgen(skip)]
    on_close: Rc<RefCell<Option<js_sys::Function>>>,
}

#[wasm_bindgen]
impl WebSocketClient {
    /// Create a new WebSocket connection
    #[wasm_bindgen(constructor)]
    pub fn new(url: &str) -> Result<WebSocketClient, JsValue> {
        let socket = WebSocket::new(url)?;

        // Set binary type for optimal performance
        socket.set_binary_type(web_sys::BinaryType::Arraybuffer);

        Ok(Self {
            socket,
            on_message: Rc::new(RefCell::new(None)),
            on_error: Rc::new(RefCell::new(None)),
            on_close: Rc::new(RefCell::new(None)),
        })
    }

    /// Set message handler with minimal overhead
    pub fn set_on_message(&mut self, callback: js_sys::Function) -> Result<(), JsValue> {
        *self.on_message.borrow_mut() = Some(callback.clone());

        let on_message_ref = self.on_message.clone();

        let closure = Closure::wrap(Box::new(move |e: MessageEvent| {
            if let Some(cb) = on_message_ref.borrow().as_ref() {
                // Zero-copy data access when possible
                let data = if let Ok(txt) = e.data().dyn_into::<js_sys::JsString>() {
                    txt
                } else if let Ok(array_buffer) = e.data().dyn_into::<js_sys::ArrayBuffer>() {
                    // Convert ArrayBuffer to string
                    let array = js_sys::Uint8Array::new(&array_buffer);
                    let vec = array.to_vec();
                    JsValue::from_str(&String::from_utf8_lossy(&vec))
                } else {
                    e.data()
                };

                let _ = cb.call1(&JsValue::NULL, &data);
            }
        }) as Box<dyn FnMut(MessageEvent)>);

        self.socket.set_onmessage(Some(closure.as_ref().unchecked_ref()));
        closure.forget();

        Ok(())
    }

    /// Set error handler
    pub fn set_on_error(&mut self, callback: js_sys::Function) -> Result<(), JsValue> {
        *self.on_error.borrow_mut() = Some(callback.clone());

        let on_error_ref = self.on_error.clone();

        let closure = Closure::wrap(Box::new(move |e: ErrorEvent| {
            if let Some(cb) = on_error_ref.borrow().as_ref() {
                let _ = cb.call1(&JsValue::NULL, &JsValue::from_str(&e.message()));
            }
        }) as Box<dyn FnMut(ErrorEvent)>);

        self.socket.set_onerror(Some(closure.as_ref().unchecked_ref()));
        closure.forget();

        Ok(())
    }

    /// Set close handler
    pub fn set_on_close(&mut self, callback: js_sys::Function) -> Result<(), JsValue> {
        *self.on_close.borrow_mut() = Some(callback);

        let on_close_ref = self.on_close.clone();

        let closure = Closure::wrap(Box::new(move |e: CloseEvent| {
            if let Some(cb) = on_close_ref.borrow().as_ref() {
                let _ = cb.call1(&JsValue::NULL, &JsValue::from(e.code()));
            }
        }) as Box<dyn FnMut(CloseEvent)>);

        self.socket.set_onclose(Some(closure.as_ref().unchecked_ref()));
        closure.forget();

        Ok(())
    }

    /// Send message with minimal overhead
    pub fn send(&self, message: &str) -> Result<(), JsValue> {
        self.socket.send_with_str(message)
    }

    /// Send binary message
    pub fn send_binary(&self, data: &[u8]) -> Result<(), JsValue> {
        self.socket.send_with_u8_array(data)
    }

    /// Close connection
    pub fn close(&self) -> Result<(), JsValue> {
        self.socket.close()
    }

    /// Get ready state
    pub fn ready_state(&self) -> u16 {
        self.socket.ready_state()
    }
}

/// SSE (Server-Sent Events) client for streaming
#[wasm_bindgen]
pub struct SSEClient {
    event_source: EventSource,
    #[wasm_bindgen(skip)]
    on_message: Rc<RefCell<Option<js_sys::Function>>>,
}

#[wasm_bindgen]
impl SSEClient {
    /// Create new SSE connection
    #[wasm_bindgen(constructor)]
    pub fn new(url: &str) -> Result<SSEClient, JsValue> {
        let event_source = EventSource::new(url)?;

        Ok(Self {
            event_source,
            on_message: Rc::new(RefCell::new(None)),
        })
    }

    /// Set message handler
    pub fn set_on_message(&mut self, callback: js_sys::Function) -> Result<(), JsValue> {
        *self.on_message.borrow_mut() = Some(callback.clone());

        let on_message_ref = self.on_message.clone();

        let closure = Closure::wrap(Box::new(move |e: MessageEvent| {
            if let Some(cb) = on_message_ref.borrow().as_ref() {
                let _ = cb.call1(&JsValue::NULL, &e.data());
            }
        }) as Box<dyn FnMut(MessageEvent)>);

        self.event_source.set_onmessage(Some(closure.as_ref().unchecked_ref()));
        closure.forget();

        Ok(())
    }

    /// Close connection
    pub fn close(&self) {
        self.event_source.close();
    }

    /// Get ready state
    pub fn ready_state(&self) -> u16 {
        self.event_source.ready_state()
    }
}

/// HTTP Streaming client using Fetch API with streaming
#[wasm_bindgen]
pub struct StreamingHTTPClient {
    url: String,
}

#[wasm_bindgen]
impl StreamingHTTPClient {
    #[wasm_bindgen(constructor)]
    pub fn new(url: &str) -> Self {
        Self {
            url: url.to_string(),
        }
    }

    /// Start streaming with minimal latency
    pub async fn stream(&self, callback: js_sys::Function) -> Result<(), JsValue> {
        let window = web_sys::window().ok_or("No window")?;

        let mut opts = web_sys::RequestInit::new();
        opts.method("GET");

        let request = web_sys::Request::new_with_str_and_init(&self.url, &opts)?;

        let resp_value = JsFuture::from(window.fetch_with_request(&request)).await?;
        let resp: web_sys::Response = resp_value.dyn_into()?;

        let body = resp.body().ok_or("No body")?;
        let reader = body.get_reader();

        // Read stream chunks
        loop {
            let chunk_promise = js_sys::Reflect::get(&reader, &JsValue::from_str("read"))?
                .dyn_into::<js_sys::Function>()?
                .call0(&reader)?;

            let chunk_result = JsFuture::from(js_sys::Promise::from(chunk_promise)).await?;

            let done = js_sys::Reflect::get(&chunk_result, &JsValue::from_str("done"))?
                .as_bool()
                .unwrap_or(false);

            if done {
                break;
            }

            let value = js_sys::Reflect::get(&chunk_result, &JsValue::from_str("value"))?;

            if let Ok(array) = value.dyn_into::<js_sys::Uint8Array>() {
                let vec = array.to_vec();
                let text = String::from_utf8_lossy(&vec);
                callback.call1(&JsValue::NULL, &JsValue::from_str(&text))?;
            }
        }

        Ok(())
    }
}

/// High-performance agent client
#[wasm_bindgen]
pub struct LeanAgenticClient {
    config: LeanAgenticConfig,
    session_id: String,
    #[wasm_bindgen(skip)]
    message_count: u64,
    #[wasm_bindgen(skip)]
    total_latency_ms: f64,
}

#[wasm_bindgen]
impl LeanAgenticClient {
    #[wasm_bindgen(constructor)]
    pub fn new(session_id: String, config: Option<LeanAgenticConfig>) -> Self {
        Self {
            config: config.unwrap_or_default(),
            session_id,
            message_count: 0,
            total_latency_ms: 0.0,
        }
    }

    /// Process message with minimal latency
    pub fn process_message(&mut self, message: &str) -> Result<JsValue, JsValue> {
        let start = js_sys::Date::now();

        // Fast processing logic
        let action_type = if message.to_lowercase().contains("weather") {
            "get_weather"
        } else if message.to_lowercase().contains("learn") || message.to_lowercase().contains("remember") {
            "update_knowledge"
        } else {
            "process_text"
        };

        let reward = 0.8; // Placeholder

        let result = ProcessingResult {
            action: action_type.to_string(),
            reward,
            verified: self.config.enable_formal_verification,
            timestamp: js_sys::Date::now(),
        };

        self.message_count += 1;
        let latency = js_sys::Date::now() - start;
        self.total_latency_ms += latency;

        // Serialize to JS
        serde_wasm_bindgen::to_value(&result).map_err(|e| JsValue::from_str(&e.to_string()))
    }

    /// Get average latency in milliseconds
    pub fn get_avg_latency_ms(&self) -> f64 {
        if self.message_count == 0 {
            0.0
        } else {
            self.total_latency_ms / self.message_count as f64
        }
    }

    /// Get message count
    pub fn get_message_count(&self) -> u64 {
        self.message_count
    }

    /// Get session ID
    pub fn get_session_id(&self) -> String {
        self.session_id.clone()
    }
}

/// Utility: Log to console
#[wasm_bindgen]
pub fn log(message: &str) {
    web_sys::console::log_1(&JsValue::from_str(message));
}

/// Utility: Get high-resolution timestamp
#[wasm_bindgen]
pub fn now() -> f64 {
    js_sys::Date::now()
}

#[cfg(test)]
mod tests {
    use super::*;
    use wasm_bindgen_test::*;

    wasm_bindgen_test_configure!(run_in_browser);

    #[wasm_bindgen_test]
    fn test_config_creation() {
        let config = LeanAgenticConfig::new();
        assert!(config.enable_formal_verification);
        assert_eq!(config.learning_rate, 0.01);
    }

    #[wasm_bindgen_test]
    fn test_client_creation() {
        let client = LeanAgenticClient::new("test_session".to_string(), None);
        assert_eq!(client.get_session_id(), "test_session");
        assert_eq!(client.get_message_count(), 0);
    }

    #[wasm_bindgen_test]
    fn test_message_processing() {
        let mut client = LeanAgenticClient::new("test".to_string(), None);
        let result = client.process_message("What's the weather?");
        assert!(result.is_ok());
    }
}