// # References
//
// "The Content-Disposition Header Field" https://www.ietf.org/rfc/rfc2183.txt
// "The Content-Disposition Header Field in the Hypertext Transfer Protocol (HTTP)" https://www.ietf.org/rfc/rfc6266.txt
// "Returning Values from Forms: multipart/form-data" https://www.ietf.org/rfc/rfc2388.txt
// Browser conformance tests at: http://greenbytes.de/tech/tc2231/
// IANA assignment: http://www.iana.org/assignments/cont-disp/cont-disp.xhtml

use language_tags::LanguageTag;
use header;
use header::{Header, IntoHeaderValue, Writer};
use header::shared::Charset;

use std::fmt::{self, Write};

/// The implied disposition of the content of the HTTP body.
#[derive(Clone, Debug, PartialEq)]
pub enum DispositionType {
    /// Inline implies default processing
    Inline,
    /// Attachment implies that the recipient should prompt the user to save the response locally,
    /// rather than process it normally (as per its media type).
    Attachment,
    /// Extension type.  Should be handled by recipients the same way as Attachment
    Ext(String)
}

/// A parameter to the disposition type.
#[derive(Clone, Debug, PartialEq)]
pub enum DispositionParam {
    /// A Filename consisting of a Charset, an optional LanguageTag, and finally a sequence of
    /// bytes representing the filename
    Filename(Charset, Option<LanguageTag>, Vec<u8>),
    /// Extension type consisting of token and value.  Recipients should ignore unrecognized
    /// parameters.
    Ext(String, String)
}

/// A `Content-Disposition` header, (re)defined in [RFC6266](https://tools.ietf.org/html/rfc6266).
///
/// The Content-Disposition response header field is used to convey
/// additional information about how to process the response payload, and
/// also can be used to attach additional metadata, such as the filename
/// to use when saving the response payload locally.
///
/// # ABNF

/// ```text
/// content-disposition = "Content-Disposition" ":"
///                       disposition-type *( ";" disposition-parm )
///
/// disposition-type    = "inline" | "attachment" | disp-ext-type
///                       ; case-insensitive
///
/// disp-ext-type       = token
///
/// disposition-parm    = filename-parm | disp-ext-parm
///
/// filename-parm       = "filename" "=" value
///                     | "filename*" "=" ext-value
///
/// disp-ext-parm       = token "=" value
///                     | ext-token "=" ext-value
///
/// ext-token           = <the characters in token, followed by "*">
/// ```
///
/// # Example
///
/// ```
/// use actix_web::http::header::{ContentDisposition, DispositionType, DispositionParam, Charset};
///
/// let cd1 = ContentDisposition {
///     disposition: DispositionType::Attachment,
///     parameters: vec![DispositionParam::Filename(
///       Charset::Iso_8859_1, // The character set for the bytes of the filename
///       None, // The optional language tag (see `language-tag` crate)
///       b"\xa9 Copyright 1989.txt".to_vec() // the actual bytes of the filename
///     )]
/// };
///
/// let cd2 = ContentDisposition {
///     disposition: DispositionType::Inline,
///     parameters: vec![DispositionParam::Filename(
///       Charset::Ext("UTF-8".to_owned()),
///       None,
///       "\u{2764}".as_bytes().to_vec()
///     )]
/// };
/// ```
#[derive(Clone, Debug, PartialEq)]
pub struct ContentDisposition {
    /// The disposition
    pub disposition: DispositionType,
    /// Disposition parameters
    pub parameters: Vec<DispositionParam>,
}
impl ContentDisposition {
    /// Parse a raw Content-Disposition header value
    pub fn from_raw(hv: &header::HeaderValue) -> Result<Self, ::error::ParseError> {
        header::from_one_raw_str(Some(hv)).and_then(|s: String| {
            let mut sections = s.split(';');
            let disposition = match sections.next() {
                Some(s) => s.trim(),
                None => return Err(::error::ParseError::Header),
            };

            let mut cd = ContentDisposition {
                disposition: if disposition.eq_ignore_ascii_case("inline") {
                    DispositionType::Inline
                } else if disposition.eq_ignore_ascii_case("attachment") {
                    DispositionType::Attachment
                } else {
                    DispositionType::Ext(disposition.to_owned())
                },
                parameters: Vec::new(),
            };

            for section in sections {
                let mut parts = section.splitn(2, '=');

                let key = if let Some(key) = parts.next() {
                    key.trim()
                } else {
                    return Err(::error::ParseError::Header);
                };

                let val = if let Some(val) = parts.next() {
                    val.trim()
                } else {
                    return Err(::error::ParseError::Header);
                };

                cd.parameters.push(
                    if key.eq_ignore_ascii_case("filename") {
                        DispositionParam::Filename(
                            Charset::Ext("UTF-8".to_owned()), None,
                            val.trim_matches('"').as_bytes().to_owned())
                    } else if key.eq_ignore_ascii_case("filename*") {
                        let extended_value = try!(header::parse_extended_value(val));
                        DispositionParam::Filename(extended_value.charset, extended_value.language_tag, extended_value.value)
                    } else {
                        DispositionParam::Ext(key.to_owned(), val.trim_matches('"').to_owned())
                    }
                );
            }

            Ok(cd)
        })
    }
}

impl IntoHeaderValue for ContentDisposition {
    type Error = header::InvalidHeaderValueBytes;

    fn try_into(self) -> Result<header::HeaderValue, Self::Error> {
        let mut writer = Writer::new();
        let _ = write!(&mut writer, "{}", self);
        header::HeaderValue::from_shared(writer.take())
    }
}

impl Header for ContentDisposition {
    fn name() -> header::HeaderName {
        header::CONTENT_DISPOSITION
    }

    fn parse<T: ::HttpMessage>(msg: &T) -> Result<Self, ::error::ParseError> {
        if let Some(h) = msg.headers().get(Self::name()) {
            Self::from_raw(&h)
        } else {
            Err(::error::ParseError::Header)
        }
    }
}

impl fmt::Display for ContentDisposition {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self.disposition {
            DispositionType::Inline => try!(write!(f, "inline")),
            DispositionType::Attachment => try!(write!(f, "attachment")),
            DispositionType::Ext(ref s) => try!(write!(f, "{}", s)),
        }
        for param in &self.parameters {
            match *param {
                DispositionParam::Filename(ref charset, ref opt_lang, ref bytes) => {
                    let mut use_simple_format: bool = false;
                    if opt_lang.is_none() {
                        if let Charset::Ext(ref ext) = *charset {
                            if ext.eq_ignore_ascii_case("utf-8") {
                                use_simple_format = true;
                            }
                        }
                    }
                    if use_simple_format {
                        use std::str;
                        try!(write!(f, "; filename=\"{}\"",
                                    match str::from_utf8(bytes) {
                                        Ok(s) => s,
                                        Err(_) => return Err(fmt::Error),
                                    }));
                    } else {
                        try!(write!(f, "; filename*={}'", charset));
                        if let Some(ref lang) = *opt_lang {
                            try!(write!(f, "{}", lang));
                        };
                        try!(write!(f, "'"));
                        try!(header::http_percent_encode(f, bytes))
                    }
                },
                DispositionParam::Ext(ref k, ref v) => try!(write!(f, "; {}=\"{}\"", k, v)),
            }
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::{ContentDisposition,DispositionType,DispositionParam};
    use header::HeaderValue;
    use header::shared::Charset;
    #[test]
    fn test_from_raw() {
        assert!(ContentDisposition::from_raw(&HeaderValue::from_static("")).is_err());

        let a = HeaderValue::from_static("form-data; dummy=3; name=upload; filename=\"sample.png\"");
        let a: ContentDisposition = ContentDisposition::from_raw(&a).unwrap();
        let b = ContentDisposition {
            disposition: DispositionType::Ext("form-data".to_owned()),
            parameters: vec![
                DispositionParam::Ext("dummy".to_owned(), "3".to_owned()),
                DispositionParam::Ext("name".to_owned(), "upload".to_owned()),
                DispositionParam::Filename(
                    Charset::Ext("UTF-8".to_owned()),
                    None,
                    "sample.png".bytes().collect()) ]
        };
        assert_eq!(a, b);

        let a = HeaderValue::from_static("attachment; filename=\"image.jpg\"");
        let a: ContentDisposition = ContentDisposition::from_raw(&a).unwrap();
        let b = ContentDisposition {
            disposition: DispositionType::Attachment,
            parameters: vec![
                DispositionParam::Filename(
                    Charset::Ext("UTF-8".to_owned()),
                    None,
                    "image.jpg".bytes().collect()) ]
        };
        assert_eq!(a, b);

        let a = HeaderValue::from_static("attachment; filename*=UTF-8''%c2%a3%20and%20%e2%82%ac%20rates");
        let a: ContentDisposition = ContentDisposition::from_raw(&a).unwrap();
        let b = ContentDisposition {
            disposition: DispositionType::Attachment,
            parameters: vec![
                DispositionParam::Filename(
                    Charset::Ext("UTF-8".to_owned()),
                    None,
                    vec![0xc2, 0xa3, 0x20, b'a', b'n', b'd', 0x20,
                         0xe2, 0x82, 0xac, 0x20, b'r', b'a', b't', b'e', b's']) ]
        };
        assert_eq!(a, b);
    }

    #[test]
    fn test_display() {
        let as_string = "attachment; filename*=UTF-8'en'%C2%A3%20and%20%E2%82%AC%20rates";
        let a = HeaderValue::from_static(as_string);
        let a: ContentDisposition = ContentDisposition::from_raw(&a).unwrap();
        let display_rendered = format!("{}",a);
        assert_eq!(as_string, display_rendered);

        let a = HeaderValue::from_static("attachment; filename*=UTF-8''black%20and%20white.csv");
        let a: ContentDisposition = ContentDisposition::from_raw(&a).unwrap();
        let display_rendered = format!("{}",a);
        assert_eq!("attachment; filename=\"black and white.csv\"".to_owned(), display_rendered);

        let a = HeaderValue::from_static("attachment; filename=colourful.csv");
        let a: ContentDisposition = ContentDisposition::from_raw(&a).unwrap();
        let display_rendered = format!("{}",a);
        assert_eq!("attachment; filename=\"colourful.csv\"".to_owned(), display_rendered);
    }
}