oxidite-core 2.2.0

use crate::error::{Error, Result};
use crate::types::{OxiditeRequest, OxiditeResponse};
use crate::extract::FromRequest;
use hyper::Method;
use std::collections::HashMap;
use std::future::Future;
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};
use tower_service::Service;
use regex::Regex;

/// Trait for type-erased handlers stored in the router
pub trait Endpoint: Send + Sync + 'static {
    fn call(&self, req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>>;
}

/// Trait for async functions that can be used as handlers
pub trait Handler<Args>: Clone + Send + Sync + 'static {
    fn call(&self, req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>>;
}

// Wrapper to convert Handler<Args> into Endpoint
struct HandlerService<H, Args> {
    handler: H,
    _marker: std::marker::PhantomData<Args>,
}

impl<H, Args> Endpoint for HandlerService<H, Args>
where
    H: Handler<Args>,
    Args: Send + Sync + 'static,
{
    fn call(&self, req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>> {
        self.handler.call(req)
    }
}

// Implement Handler for Fn(OxiditeRequest) -> Fut
impl<F, Fut> Handler<OxiditeRequest> for F
where
    F: Fn(OxiditeRequest) -> Fut + Clone + Send + Sync + 'static,
    Fut: Future<Output = Result<OxiditeResponse>> + Send + 'static,
{
    fn call(&self, req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>> {
        let fut = self(req);
        Box::pin(async move { fut.await })
    }
}

// Implement Handler for Fn() -> Fut
impl<F, Fut> Handler<()> for F
where
    F: Fn() -> Fut + Clone + Send + Sync + 'static,
    Fut: Future<Output = Result<OxiditeResponse>> + Send + 'static,
{
    fn call(&self, _req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>> {
        let fut = self();
        Box::pin(async move { fut.await })
    }
}

// Implement Handler for Fn(T1) -> Fut
impl<F, Fut, T1> Handler<(T1,)> for F
where
    F: Fn(T1) -> Fut + Clone + Send + Sync + 'static,
    Fut: Future<Output = Result<OxiditeResponse>> + Send + 'static,
    T1: FromRequest + Send + 'static,
{
    fn call(&self, mut req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>> {
        let handler = self.clone();
        Box::pin(async move {
            let t1 = T1::from_request(&mut req).await?;
            handler(t1).await
        })
    }
}

// Implement Handler for Fn(T1, T2) -> Fut
impl<F, Fut, T1, T2> Handler<(T1, T2)> for F
where
    F: Fn(T1, T2) -> Fut + Clone + Send + Sync + 'static,
    Fut: Future<Output = Result<OxiditeResponse>> + Send + 'static,
    T1: FromRequest + Send + 'static,
    T2: FromRequest + Send + 'static,
{
    fn call(&self, mut req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>> {
        let handler = self.clone();
        Box::pin(async move {
            let t1 = T1::from_request(&mut req).await?;
            let t2 = T2::from_request(&mut req).await?;
            handler(t1, t2).await
        })
    }
}

// Implement Handler for Fn(T1, T2, T3) -> Fut
impl<F, Fut, T1, T2, T3> Handler<(T1, T2, T3)> for F
where
    F: Fn(T1, T2, T3) -> Fut + Clone + Send + Sync + 'static,
    Fut: Future<Output = Result<OxiditeResponse>> + Send + 'static,
    T1: FromRequest + Send + 'static,
    T2: FromRequest + Send + 'static,
    T3: FromRequest + Send + 'static,
{
    fn call(&self, mut req: OxiditeRequest) -> Pin<Box<dyn Future<Output = Result<OxiditeResponse>> + Send>> {
        let handler = self.clone();
        Box::pin(async move {
            let t1 = T1::from_request(&mut req).await?;
            let t2 = T2::from_request(&mut req).await?;
            let t3 = T3::from_request(&mut req).await?;
            handler(t1, t2, t3).await
        })
    }
}

struct Route {
    pattern: Regex,
    param_names: Vec<String>,
    handler: Arc<dyn Endpoint>,
}

#[derive(Clone)]
pub struct Router {
    routes: HashMap<Method, Vec<Arc<Route>>>,
    extensions: Arc<std::sync::RwLock<http::Extensions>>,
}

impl Router {
    pub fn new() -> Self {
        Self {
            routes: HashMap::new(),
            extensions: Arc::new(std::sync::RwLock::new(http::Extensions::new())),
        }
    }

    /// Add a shared state to the router that will be available in all handlers
    pub fn with_state<T: Clone + Send + Sync + 'static>(&mut self, state: T) {
        if let Ok(mut exts) = self.extensions.write() {
            exts.insert(state);
        }
    }

    pub fn get<H, Args>(&mut self, path: &str, handler: H)
    where
        H: Handler<Args>,
        Args: Send + Sync + 'static,
    {
        self.add_route(Method::GET, path, handler);
    }
    
    pub fn post<H, Args>(&mut self, path: &str, handler: H)
    where
        H: Handler<Args>,
        Args: Send + Sync + 'static,
    {
        self.add_route(Method::POST, path, handler);
    }

    pub fn put<H, Args>(&mut self, path: &str, handler: H)
    where
        H: Handler<Args>,
        Args: Send + Sync + 'static,
    {
        self.add_route(Method::PUT, path, handler);
    }

    pub fn delete<H, Args>(&mut self, path: &str, handler: H)
    where
        H: Handler<Args>,
        Args: Send + Sync + 'static,
    {
        self.add_route(Method::DELETE, path, handler);
    }

    pub fn patch<H, Args>(&mut self, path: &str, handler: H)
    where
        H: Handler<Args>,
        Args: Send + Sync + 'static,
    {
        self.add_route(Method::PATCH, path, handler);
    }

    fn add_route<H, Args>(&mut self, method: Method, path: &str, handler: H)
    where
        H: Handler<Args>,
        Args: Send + Sync + 'static,
    {
        let (pattern, param_names) = compile_path(path);
        let endpoint = HandlerService {
            handler,
            _marker: std::marker::PhantomData,
        };
        
        let route = Arc::new(Route {
            pattern,
            param_names,
            handler: Arc::new(endpoint),
        });
        
        self.routes
            .entry(method)
            .or_insert_with(Vec::new)
            .push(route);
    }

    pub async fn handle(&self, mut req: OxiditeRequest) -> Result<OxiditeResponse> {
        let method = req.method().clone();
        let path = req.uri().path().to_string();

        // Helper to try matching routes for a specific method
        let try_match = |target_method: &Method, req: &mut OxiditeRequest| -> Option<Arc<Route>> {
            if let Some(routes) = self.routes.get(target_method) {
                for route in routes {
                    if let Some(captures) = route.pattern.captures(&path) {
                        // Extract path parameters
                        let mut params = serde_json::Map::new();
                        for (i, name) in route.param_names.iter().enumerate() {
                            if let Some(value) = captures.get(i + 1) {
                                params.insert(
                                    name.clone(),
                                    serde_json::Value::String(value.as_str().to_string()),
                                );
                            }
                        }

                        // Store params in request extensions
                        if !params.is_empty() {
                            req.extensions_mut().insert(crate::extract::PathParams(
                                serde_json::Value::Object(params),
                            ));
                        }
                        
                        return Some(route.clone());
                    }
                }
            }
            None
        };

        // 1. Try exact method match
        if let Some(route) = try_match(&method, &mut req) {
            return route.handler.call(req).await;
        }

        // 2. If HEAD, try GET
        if method == Method::HEAD {
            if let Some(route) = try_match(&Method::GET, &mut req) {
                // For HEAD requests, we execute the GET handler but the server/hyper 
                // will strip the body automatically since it's a HEAD response.
                return route.handler.call(req).await;
            }
        }

        // 3. Path exists for other methods => method not allowed
        let allowed_methods: Vec<String> = self
            .routes
            .iter()
            .filter(|(route_method, _)| **route_method != method)
            .filter_map(|(route_method, routes)| {
                if routes.iter().any(|route| route.pattern.is_match(&path)) {
                    Some(route_method.as_str().to_string())
                } else {
                    None
                }
            })
            .collect();
        if !allowed_methods.is_empty() {
            return Err(Error::MethodNotAllowed(format!(
                "{} {} (allowed: {})",
                method,
                path,
                allowed_methods.join(", ")
            )));
        }

        Err(Error::NotFound("Route not found".to_string()))
    }
}

impl Service<OxiditeRequest> for Router {
    type Response = OxiditeResponse;
    type Error = Error;
    type Future = Pin<Box<dyn Future<Output = Result<Self::Response>> + Send>>;

    fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<std::result::Result<(), Self::Error>> {
        Poll::Ready(Ok(()))
    }

    fn call(&mut self, req: OxiditeRequest) -> Self::Future {
        let router = self.clone();
        Box::pin(async move {
            router.handle(req).await
        })
    }
}

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

/// Compile a route path pattern into a regex
/// Converts `/users/:id` to `^/users/([^/]+)$` and returns param names
fn compile_path(path: &str) -> (Regex, Vec<String>) {
    let mut pattern = String::from("^");
    let mut param_names = Vec::new();
    let mut chars = path.chars().peekable();

    while let Some(ch) = chars.next() {
        match ch {
            ':' => {
                // Extract parameter name
                let mut param_name = String::new();
                while let Some(&next_ch) = chars.peek() {
                    if next_ch.is_alphanumeric() || next_ch == '_' {
                        param_name.push(next_ch);
                        chars.next();
                    } else {
                        break;
                    }
                }
                param_names.push(param_name);
                pattern.push_str("([^/]+)");
            }
            '*' => {
                // Wildcard
                pattern.push_str("(.*)");
            }
            '.' | '+' | '?' | '^' | '$' | '(' | ')' | '[' | ']' | '{' | '}' | '|' | '\\' => {
                // Escape regex special characters
                pattern.push('\\');
                pattern.push(ch);
            }
            _ => {
                pattern.push(ch);
            }
        }
    }

    pattern.push('$');
    let regex = Regex::new(&pattern).expect("Invalid route pattern");
    (regex, param_names)
}

/// Trait that provides compile-time verification that a function is a valid handler.
///
/// This is used by the [`handler_fn`] function to give clear, readable error messages
/// when a function doesn't satisfy the handler requirements, rather than the cryptic
/// trait-bound errors that would otherwise surface from the router.
///
/// # Example
///
/// ```rust,ignore
/// use oxidite::prelude::*;
///
/// // This compiles because the function matches Handler<(State<Arc<AppState>>,)>
/// let h = handler_fn(my_handler);
/// router.get("/users", h);
///
/// // This would fail at compile time with a clear error if the function
/// // has extractors that don't implement FromRequest.
/// ```
pub trait IntoHandler<Args>: Handler<Args> + Sized {
    fn into_handler(self) -> Self {
        self
    }
}

impl<H, Args> IntoHandler<Args> for H where H: Handler<Args> {}

/// Compile-time handler verification helper.
///
/// Wraps a handler function and ensures at compile time that all its extractors
/// implement `FromRequest`. Provides clearer error messages than raw trait bounds.
///
/// # Example
///
/// ```rust,ignore
/// use oxidite::prelude::*;
///
/// async fn index(State(s): State<Arc<AppState>>) -> Result<OxiditeResponse> {
///     Ok(response::json(serde_json::json!({"ok": true})))
/// }
///
/// // Verified at compile time:
/// router.get("/", handler_fn(index));
/// ```
pub fn handler_fn<H, Args>(handler: H) -> H
where
    H: IntoHandler<Args>,
    Args: Send + Sync + 'static,
{
    handler
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::types::BoxBody;

    #[test]
    fn test_compile_path() {
        let (regex, params) = compile_path("/users/:id");
        assert_eq!(params, vec!["id"]);
        assert!(regex.is_match("/users/123"));
        assert!(!regex.is_match("/users/123/posts"));

        let (regex, params) = compile_path("/users/:user_id/posts/:post_id");
        assert_eq!(params, vec!["user_id", "post_id"]);
        assert!(regex.is_match("/users/1/posts/2"));
    }

    #[test]
    fn test_exact_match() {
        let (regex, params) = compile_path("/users");
        assert_eq!(params.len(), 0);
        assert!(regex.is_match("/users"));
        assert!(!regex.is_match("/users/123"));
    }

    #[tokio::test]
    async fn test_method_not_allowed_when_path_exists() {
        let mut router = Router::new();
        router.get("/users", || async { Ok(crate::OxiditeResponse::text("ok")) });
        let req = http::Request::builder()
            .method(Method::POST)
            .uri("/users")
            .body(BoxBody::default())
            .expect("request");

        let result = router.handle(req).await;
        assert!(matches!(result, Err(Error::MethodNotAllowed(_))));
    }

    #[tokio::test]
    async fn test_not_found_when_path_missing() {
        let router = Router::new();
        let req = http::Request::builder()
            .method(Method::GET)
            .uri("/missing")
            .body(BoxBody::default())
            .expect("request");

        let result = router.handle(req).await;
        assert!(matches!(result, Err(Error::NotFound(_))));
    }
}