//! Provides the [`Parts`] and [`Body`] convenience wrappers.

use cookie::Cookie;
use header::CONTENT_TYPE;
use mime::{APPLICATION_WWW_FORM_URLENCODED, Mime};
use serde::{Deserialize, de::DeserializeOwned};
use hyper::{body::Bytes, header};
use hyper::http::request::Parts as ReqParts;
use std::collections::HashMap;

use crate::{Error, security};

type HyperRequest = hyper::Request<hyper::Body>;

/// Convenience wrapper around [`hyper::Body`].
pub struct Body {
    body: hyper::Body,
    content_type: Option<header::HeaderValue>,
}

/// Convert [`hyper::Request`] to ([`Parts`], [`Body`])
pub fn adapt<'a>(req: HyperRequest) -> (Parts, Body) {
    let (parts, body) = req.into_parts();
    let body = Body{body, content_type: parts.headers.get(CONTENT_TYPE).map(|x| x.to_owned())};
    let parts = Parts{parts, cookies: None};
    (parts, body)
}

/// Convenience wrapper around [`hyper::http::request::Parts`].
pub struct Parts {
    parts: ReqParts,
    cookies: Option<HashMap<String,Cookie<'static>>>,
}

#[derive(Deserialize)]
struct CsrfData {
    csrf: String,
}

impl Parts {
    pub fn cookies(&mut self) -> &HashMap<String,Cookie> {
        if let Some(ref cookies) = self.cookies {
            return cookies
        }
        let mut cookies = HashMap::new();
        for header in self.parts.headers.get_all(header::COOKIE) {
            let raw_str = match std::str::from_utf8(header.as_bytes()) {
                Ok(string) => string,
                Err(_) => continue
            };

            for cookie_str in raw_str.split(';').map(|s| s.trim()) {
                if let Ok(cookie) = Cookie::parse_encoded(cookie_str) {
                    cookies.insert(cookie.name().to_string(), cookie.into_owned());
                }
            }
        }
        self.cookies = Some(cookies);
        &self.cookies.as_ref().unwrap()
    }

    pub fn method(&self) -> &hyper::Method {
        &self.parts.method
    }

    pub fn headers(&self) -> &hyper::HeaderMap<header::HeaderValue> {
        &self.parts.headers
    }

    pub fn uri(&self) -> &hyper::Uri {
        &self.parts.uri
    }

    /// Parses the query string of the request into a given struct.
    pub fn query<T: DeserializeOwned>(&self) -> Result<T,Error> {
        serde_urlencoded::from_str::<T>(self.parts.uri.query().unwrap_or("")).map_err(|e|Error::bad_request(e.to_string()))
    }
}

impl Body {
    pub async fn into_bytes(self) -> Result<Bytes,Error> {
        hyper::body::to_bytes(self.body).await.map_err(|_|Error::internal("failed to read body".to_string()))
    }

    /// Parses a `application/x-www-form-urlencoded` request body into a given struct.
    ///
    /// This does make you vulnerable to CSRF, so you normally want to use
    /// [`Body::into_form_csrf()`] instead.
    ///
    /// # Example
    ///
    /// ```
    /// use hyper::{Response};
    /// use sputnik::{request::Body, Error};
    /// use serde::Deserialize;
    ///
    /// #[derive(Deserialize)]
    /// struct Message {text: String, year: i64}
    ///
    /// async fn greet(body: Body) -> Result<Response<hyper::Body>, Error> {
    ///     let msg: Message = body.into_form().await?;
    ///     Ok(Response::new(format!("hello {}", msg.text).into()))
    /// }
    /// ```
    pub async fn into_form<T: DeserializeOwned>(self) -> Result<T,Error> {
        self.enforce_content_type(APPLICATION_WWW_FORM_URLENCODED)?;
        let full_body = self.into_bytes().await?;
        serde_urlencoded::from_bytes::<T>(&full_body).map_err(|e|Error::bad_request(e.to_string()))
    }

    /// Parses a `application/x-www-form-urlencoded` request body into a given struct.
    /// Protects from CSRF by checking that the request body contains the same token retrieved from the cookies.
    ///
    /// The CSRF parameter is expected as the `csrf` parameter in the request body.
    /// This means for HTML forms you need to embed the token as a hidden input.
    ///
    /// # Example
    ///
    /// ```
    /// use hyper::{Method};
    /// use sputnik::{request::{Parts, Body}, response::Response, Error};
    /// use sputnik::security::CsrfToken;
    /// use serde::Deserialize;
    ///
    /// #[derive(Deserialize)]
    /// struct Message {text: String}
    ///
    /// async fn greet(req: &mut Parts, body: Body) -> Result<Response, Error> {
    ///     let mut response = Response::new();
    ///     let csrf_token = CsrfToken::from_parts(req, &mut response);
    ///     *response.body() = match (req.method()) {
    ///         &Method::GET => format!("<form method=post>
    ///             <input name=text>{}<button>Submit</button></form>", csrf_token.html_input()).into(),
    ///         &Method::POST => {
    ///             let msg: Message = body.into_form_csrf(&csrf_token).await?;
    ///             format!("hello {}", msg.text).into()
    ///         },
    ///         _ => return Err(Error::method_not_allowed("only GET and POST allowed".to_owned())),
    ///     };
    ///     Ok(response)
    /// }
    /// ```
    pub async fn into_form_csrf<T: DeserializeOwned>(self, csrf_token: &security::CsrfToken) -> Result<T,Error> {
        self.enforce_content_type(APPLICATION_WWW_FORM_URLENCODED)?;
        let full_body = self.into_bytes().await?;
        let csrf_data = serde_urlencoded::from_bytes::<CsrfData>(&full_body).map_err(|_|Error::bad_request("no csrf token".to_string()))?;
        csrf_token.matches(csrf_data.csrf)?;
        serde_urlencoded::from_bytes::<T>(&full_body).map_err(|e|Error::bad_request(e.to_string()))
    }

    fn enforce_content_type(&self, mime: Mime) -> Result<(),Error> {
        if let Some(content_type) = &self.content_type {
            if *content_type == mime.to_string() {
                return Ok(())
            }
        }
        Err(Error::bad_request(format!("expected content-type: {}", mime)))
    }
}