use std::str;
use std::str::FromStr;
use std::fmt;
use std::iter::FromIterator;

use req_resp::RequestOrResponse;

use result::Result;
use error::Error;

use assert_types::*;

use bytes::Bytes;


#[derive(Debug, PartialEq, Eq)]
pub enum PseudoHeaderName {
    // 8.1.2.3 Request Pseudo-Header Fields
    Method,
    Scheme,
    Authority,
    Path,

    // 8.1.2.4 Response Pseudo-Header Fields
    Status,
}

impl PseudoHeaderName {
    pub fn name(&self) -> &'static str {
        match *self {
            PseudoHeaderName::Method =>    ":method",
            PseudoHeaderName::Scheme =>    ":scheme",
            PseudoHeaderName::Authority => ":authority",
            PseudoHeaderName::Path =>      ":path",
            PseudoHeaderName::Status =>    ":status",
        }
    }

    pub fn parse(value: &[u8]) -> Result<PseudoHeaderName> {
        match value {
            b":method"    => Ok(PseudoHeaderName::Method),
            b":scheme"    => Ok(PseudoHeaderName::Scheme),
            b":authority" => Ok(PseudoHeaderName::Authority),
            b":path"      => Ok(PseudoHeaderName::Path),
            b":status"    => Ok(PseudoHeaderName::Status),
            _             => Err(Error::Other("invalid pseudo header")),
        }
    }

    pub fn req_or_resp(&self) -> RequestOrResponse {
        match *self {
            PseudoHeaderName::Method    => RequestOrResponse::Request,
            PseudoHeaderName::Scheme    => RequestOrResponse::Request,
            PseudoHeaderName::Authority => RequestOrResponse::Request,
            PseudoHeaderName::Path      => RequestOrResponse::Request,
            PseudoHeaderName::Status    => RequestOrResponse::Response,
        }
    }

    pub fn name_bytes(&self) -> Bytes {
        Bytes::from_static(self.name().as_bytes())
    }
}


#[allow(dead_code)]
pub struct HeaderName(Bytes);

impl<'a> From<&'a str> for HeaderName {
    fn from(_name: &'a str) -> HeaderName {
        unimplemented!()
    }
}



/// A convenience struct representing a part of a header (either the name or the value).
pub struct HeaderPart(Bytes);

impl fmt::Debug for HeaderPart {
    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
        fmt::Debug::fmt(&self.0, fmt)
    }
}

impl From<Vec<u8>> for HeaderPart {
    fn from(vec: Vec<u8>) -> HeaderPart {
        HeaderPart(Bytes::from(vec))
    }
}

impl From<Bytes> for HeaderPart {
    fn from(bytes: Bytes) -> HeaderPart {
        HeaderPart(bytes)
    }
}

impl<'a> From<&'a [u8]> for HeaderPart {
    fn from(buf: &'a [u8]) -> HeaderPart {
        HeaderPart(Bytes::from(buf))
    }
}

macro_rules! from_static_size_array {
    ($N:expr) => (
        impl<'a> From<&'a [u8; $N]> for HeaderPart {
            fn from(buf: &'a [u8; $N]) -> HeaderPart {
                buf[..].into()
            }
        }
    );
}

macro_rules! impl_from_static_size_array {
    ($($N:expr,)+) => {
        $(
            from_static_size_array!($N);
        )+
    }
}

impl_from_static_size_array!(
    0,
    1,
    2,
    3,
    4,
    5,
    6,
    7,
    8,
    9,
    10,
    11,
    12,
    13,
    14,
    15,
    16,
    17,
    18,
    19,
    20,
    21,
    22,
    23,
);

impl From<String> for HeaderPart {
    fn from(s: String) -> HeaderPart {
        From::from(s.into_bytes())
    }
}

impl<'a> From<&'a str> for HeaderPart {
    fn from(s: &'a str) -> HeaderPart {
        From::from(s.as_bytes())
    }
}

#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Header {
    pub name: Bytes,
    pub value: Bytes,
}

fn _assert_header_sync_send() {
    assert_sync::<Header>();
    assert_send::<Header>();
}

impl Header {
    /// Creates a new `Header` with the given name and value.
    ///
    /// The name and value need to be convertible into a `HeaderPart`.
    pub fn new<N: Into<HeaderPart>, V: Into<HeaderPart>>(name: N,
                                                                 value: V)
                                                                 -> Header {
        Header {
            name: name.into().0,
            value: value.into().0,
        }
    }

    /// Return a borrowed representation of the `Header` name.
    pub fn name(&self) -> &[u8] {
        &self.name
    }
    /// Return a borrowed representation of the `Header` value.
    pub fn value(&self) -> &[u8] {
        &self.value
    }

    /// name: value
    pub fn format(&self) -> String {
        format!("{}: {}", String::from_utf8_lossy(&self.name), String::from_utf8_lossy(&self.value))
    }
}

impl<N: Into<HeaderPart>, V: Into<HeaderPart>> From<(N, V)> for Header {
    fn from(p: (N, V)) -> Header {
        Header::new(p.0, p.1)
    }
}

#[derive(Default, Debug, PartialEq, Eq, Clone)]
pub struct Headers(pub Vec<Header>);

impl Headers {
    pub fn new() -> Headers {
        Default::default()
    }

    /// Multiline string
    pub fn dump(&self) -> String {
        let mut r = String::new();
        for h in &self.0 {
            r.push_str(&h.format());
            r.push_str("\n");
        }
        r
    }

    pub fn new_get(path: &str) -> Headers {
        Headers(vec![
            Header::new(":method", "GET"),
            Header::new(":path", path),
        ])
    }

    pub fn new_post(path: &str) -> Headers {
        Headers(vec![
            Header::new(":method", "POST"),
            Header::new(":path", path),
        ])
    }

    pub fn from_status(code: u32) -> Headers {
        Headers(vec![
            Header::new(":status", format!("{}", code)),
        ])
    }

    pub fn ok_200() -> Headers {
        Headers::from_status(200)
    }

    pub fn not_found_404() -> Headers {
        Headers::from_status(404)
    }

    pub fn internal_error_500() -> Headers {
        Headers::from_status(500)
    }

    pub fn get_opt<'a>(&'a self, name: &str) -> Option<&'a str> {
        self.0.iter()
            .find(|h| h.name() == name.as_bytes())
            .and_then(|h| str::from_utf8(h.value()).ok())
    }

    pub fn get<'a>(&'a self, name: &str) -> &'a str {
        self.get_opt(name).unwrap()
    }

    pub fn get_opt_parse<I : FromStr>(&self, name: &str) -> Option<I> {
        self.get_opt(name)
            .and_then(|h| h.parse().ok())
    }

    pub fn status(&self) -> u32 {
        self.get_opt_parse(":status").unwrap()
    }

    pub fn path(&self) -> &str {
        self.get(":path")
    }

    pub fn method(&self) -> &str {
        self.get(":method")
    }

    pub fn add(&mut self, name: &str, value: &str) {
        self.0.push(Header::new(name, value));
    }

    pub fn extend(&mut self, headers: Headers) {
        self.0.extend(headers.0);
    }

}

impl FromIterator<Header> for Headers {
    fn from_iter<T : IntoIterator<Item=Header>>(iter: T) -> Headers {
        Headers(iter.into_iter().collect())
    }
}

#[cfg(test)]
mod test {
    use solicit::header::Header;

    #[test]
    fn test_partial_eq_of_headers() {
        let fully_static = Header::new(b":method", b"GET");
        let static_name = Header::new(b":method", b"GET".to_vec());
        let other = Header::new(b":path", b"/");

        assert!(fully_static == static_name);
        assert!(fully_static != other);
        assert!(static_name != other);
    }

    #[test]
    fn test_debug() {
        assert_eq!(
            "Header { name: b\":method\", value: b\"GET\" }",
            format!("{:?}", Header::new(b":method", b"GET")));
        assert_eq!(
            "Header { name: b\":method\", value: b\"\\xcd\" }",
            format!("{:?}", Header::new(b":method", b"\xcd")));
    }
}