/*
 * meli - attachments module
 *
 * Copyright 2017 Manos Pitsidianakis
 *
 * This file is part of meli.
 *
 * meli is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * meli is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with meli. If not, see <http://www.gnu.org/licenses/>.
 */
use std::fmt;
use std::str;
use data_encoding::BASE64_MIME;
use mailbox::email::parser;

pub use mailbox::email::attachment_types::*;

#[derive(Clone)]
pub enum AttachmentType {
    Data {
        tag: Vec<u8>,
    },
    Text {
        content: Vec<u8>,
    },
    Multipart {
        of_type: MultipartType,
        subattachments: Vec<Attachment>,
    },
}

impl fmt::Debug for AttachmentType {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            AttachmentType::Data { .. } => write!(f, "AttachmentType::Data {{ .. }}"),
            AttachmentType::Text { .. } => write!(f, "AttachmentType::Text {{ .. }}"),
            AttachmentType::Multipart { of_type, subattachments } => write!(f, "AttachmentType::Multipart {{ of_type: {:?},\nsubattachments: {:?} }}", of_type, subattachments),
        }
    }
}

/*
 *
 * Data
 * Text { content: Vec<u8> }
 * Multipart
 */
// TODO: Add example.
//
pub struct AttachmentBuilder {
    content_type: (ContentType, ContentSubType),
    content_transfer_encoding: ContentTransferEncoding,

    raw: Vec<u8>,
}

#[derive(Clone)]
pub struct Attachment {
    content_type: (ContentType, ContentSubType),
    content_transfer_encoding: ContentTransferEncoding,

    raw: Vec<u8>,
    attachment_type: AttachmentType,
}

impl fmt::Debug for Attachment {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "Attachment {{\n content_type: {:?},\n content_transfer_encoding: {:?},\n raw: Vec of {} bytes\n attachment_type: {:?}\n }}",
        self.content_type,
        self.content_transfer_encoding,
        self.raw.len(),
        self.attachment_type)
    }
}

impl fmt::Display for AttachmentType {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            AttachmentType::Data { tag: ref t } => write!(f, "{}", String::from_utf8_lossy(t)),
            AttachmentType::Text { content: ref c } => write!(f, "{}", String::from_utf8_lossy(c)),
            AttachmentType::Multipart { of_type: ref t, .. } => write!(f, "{}", t),
        }
    }
}

impl AttachmentBuilder {
    pub fn new(content: &[u8]) -> Self {
        AttachmentBuilder {
            content_type: (Default::default() , ContentSubType::Plain),
            content_transfer_encoding: ContentTransferEncoding::_7Bit,
            raw: content.to_vec(),
        }
    }
    pub fn content_type(&mut self, value: &[u8]) -> &Self {
        match parser::content_type(value).to_full_result() {
            Ok((ct, cst, params)) => if ct.eq_ignore_ascii_case(b"multipart") {
                let mut boundary = None;
                for (n, v) in params {
                    if n.eq_ignore_ascii_case(b"boundary") {
                        let mut vec: Vec<u8> = Vec::with_capacity(v.len() + 4);
                        vec.extend_from_slice(b"--");
                        vec.extend(v);
                        vec.extend_from_slice(b"--");
                        boundary = Some(vec);
                        break;
                    }
                }
                assert!(boundary.is_some());
                self.content_type.0 = ContentType::Multipart {
                    boundary: boundary.unwrap(),
                };
                self.content_type.1 = ContentSubType::Other { tag: cst.into() };
            } else if ct.eq_ignore_ascii_case(b"text") {
                self.content_type.0 = Default::default();
                for (n, v) in params {
                    if n.eq_ignore_ascii_case(b"charset") {
                        self.content_type.0 = ContentType::Text { charset: Charset::from(v) };
                        break;
                    }
                }
                if cst.eq_ignore_ascii_case(b"html") {
                    self.content_type.1 = ContentSubType::Html;
                } else if !cst.eq_ignore_ascii_case(b"plain") {
                    self.content_type.1 = ContentSubType::Other {
                        tag: cst.to_ascii_lowercase(),
                    };
                }
            } else {
                self.content_type.0 = ContentType::Unsupported {
                    tag: ct.to_ascii_lowercase(),
                };
                self.content_type.1 = ContentSubType::Other {
                    tag: cst.to_ascii_lowercase(),
                };
            },
            Err(v) => {
                eprintln!("parsing error in content_type: {:?} {:?}", value, v);
            }
        }
        self
    }
    pub fn content_transfer_encoding(&mut self, value: &[u8]) -> &Self {
        self.content_transfer_encoding = if value.eq_ignore_ascii_case(b"base64") {
            ContentTransferEncoding::Base64
        } else if value.eq_ignore_ascii_case(b"7bit") {
            ContentTransferEncoding::_7Bit
        } else if value.eq_ignore_ascii_case(b"8bit") {
            ContentTransferEncoding::_8Bit
        } else if value.eq_ignore_ascii_case(b"quoted-printable") {
            ContentTransferEncoding::QuotedPrintable
        } else {
            ContentTransferEncoding::Other {
                tag: value.to_ascii_lowercase(),
            }
        };
        self
    }
    fn decode(&self) -> Vec<u8> {
        // TODO merge this and standalone decode() function
        let charset = match self.content_type.0 {
            ContentType::Text{ charset: c } => c,
            _ => Default::default(),
        };

        let bytes = match self.content_transfer_encoding {
            ContentTransferEncoding::Base64 => match BASE64_MIME.decode(&self.raw) {
                Ok(v) => v,
                _ => self.raw.to_vec(),
            },
            ContentTransferEncoding::QuotedPrintable => parser::quoted_printable_bytes(&self.raw)
                .to_full_result()
                .unwrap(),
                ContentTransferEncoding::_7Bit
                    | ContentTransferEncoding::_8Bit
                    | ContentTransferEncoding::Other { .. } => self.raw.to_vec(),
        };

        let decoded_result = parser::decode_charset(&bytes, charset);
        decoded_result.as_ref().map(|v| v.as_bytes()).unwrap_or_else(|_| &self.raw).to_vec()
    }
    pub fn build(self) -> Attachment {
        let attachment_type = match self.content_type.0 {
            ContentType::Text { .. } => AttachmentType::Text {
                content: self.decode(),
            },
            ContentType::Multipart { boundary: ref b } => {
                let multipart_type = match self.content_type.1 {
                    ContentSubType::Other { ref tag } => match &tag[..] {
                        b"mixed" | b"Mixed" | b"MIXED" => MultipartType::Mixed,
                        b"alternative" | b"Alternative" | b"ALTERNATIVE" => MultipartType::Alternative,
                        b"digest" | b"Digest" | b"DIGEST" => MultipartType::Digest,
                        _ => MultipartType::Unsupported { tag: tag.clone() },
                    },
                    _ => panic!(),
                };
                AttachmentType::Multipart {
                    of_type: multipart_type,
                    subattachments: Self::subattachments(&self.raw, b),
                }
            }
            ContentType::Unsupported { ref tag } => AttachmentType::Data { tag: tag.clone() },
        };
        Attachment {
            content_type: self.content_type,
            content_transfer_encoding: self.content_transfer_encoding,
            raw: self.raw,
            attachment_type: attachment_type,
        }
    }

    pub fn subattachments(raw: &[u8], boundary: &[u8]) -> Vec<Attachment> {
        let boundary_length = boundary.len();
        match parser::attachments(raw, &boundary[0..boundary_length - 2], boundary).to_full_result()
        {
            Ok(attachments) => {
                let mut vec = Vec::with_capacity(attachments.len());
                for a in attachments {
                    let (headers, body) = match parser::attachment(a).to_full_result() {
                        Ok(v) => v,
                        Err(_) => {
                            eprintln!("error in parsing attachment");
                            eprintln!("\n-------------------------------");
                            eprintln!("{}\n", ::std::string::String::from_utf8_lossy(a));
                            eprintln!("-------------------------------\n");

                            continue;
                        }
                    };
                    let mut builder = AttachmentBuilder::new(body);
                    for (name, value) in headers {
                        if name.eq_ignore_ascii_case(b"content-type") {
                            builder.content_type(value);
                        } else if name.eq_ignore_ascii_case(b"content-transfer-encoding") {
                            builder.content_transfer_encoding(value);
                        }
                    }
                    vec.push(builder.build());
                }
                vec
            }
            a => {
                eprintln!(
                    "error {:?}\n\traw: {:?}\n\tboundary: {:?}",
                    a,
                    str::from_utf8(raw).unwrap(),
                    boundary
                );
                Vec::new()
            }
        }
    }
}


impl fmt::Display for Attachment {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self.attachment_type {
            AttachmentType::Data { .. } => {
                write!(f, "Data attachment of type {}", self.mime_type())
            }
            AttachmentType::Text { .. } => write!(f, "Text attachment of type {}", self.mime_type()),
            AttachmentType::Multipart {
                of_type: ref multipart_type,
                subattachments: ref sub_att_vec,
            } => if *multipart_type == MultipartType::Alternative {
                write!(
                    f,
                    "{} attachment with {} subs",
                    self.mime_type(), sub_att_vec.len()
                )
            } else {
                write!(f, "{} attachment with {} subs", self.mime_type(), sub_att_vec.len())
            },
        }
    }
}

impl Attachment {
    pub fn bytes(&self) -> &[u8] {
        &self.raw
    }
    fn get_text_recursive(&self, text: &mut Vec<u8>) {
        match self.attachment_type {
            AttachmentType::Data { .. } => {
                //text.push_str(&format!("Data attachment of type {}", self.mime_type()));
            }
            AttachmentType::Text { .. } => {
                text.extend(decode(self, None));
            }
            AttachmentType::Multipart {
                of_type: ref multipart_type,
                subattachments: ref sub_att_vec,
            } => if *multipart_type == MultipartType::Alternative {
                for a in sub_att_vec {
                    if a.content_type.1 == ContentSubType::Plain {
                        a.get_text_recursive(text);
                        break;
                    }
                }
            } else {
                for a in sub_att_vec {
                    a.get_text_recursive(text);
                    text.extend_from_slice(b"\n\n");
                }
            },
        }
    }
    pub fn text(&self) -> String {
        let mut text = Vec::with_capacity(self.raw.len());
        self.get_text_recursive(&mut text);
        String::from_utf8_lossy(&text).into()
    }
    pub fn description(&self) -> Vec<String> {
        self.attachments().iter().map(|a| a.text()).collect()
    }
    pub fn mime_type(&self) -> String {
        format!("{}/{}", self.content_type.0, self.content_type.1).to_string()
    }
    pub fn attachments(&self) -> Vec<Attachment> {
        let mut ret = Vec::new();
        fn count_recursive(att: &Attachment, ret: &mut Vec<Attachment>) {
            match att.attachment_type {
                AttachmentType::Data { .. } | AttachmentType::Text { .. } => ret.push(att.clone()),
                AttachmentType::Multipart {
                    of_type: _,
                    subattachments: ref sub_att_vec,
                } => {
                    ret.push(att.clone());
                    // TODO: Fix this, wrong count
                    for a in sub_att_vec {
                        count_recursive(a, ret);
                    }
                },
            }
        }

        count_recursive(&self, &mut ret);
        ret
    }
    pub fn count_attachments(&self) -> usize {
        self.attachments().len()
    }
    pub fn attachment_type(&self) -> &AttachmentType {
        &self.attachment_type
    }
    pub fn content_type(&self) -> &(ContentType, ContentSubType) {
        &self.content_type
    }
    pub fn content_transfer_encoding(&self) -> &ContentTransferEncoding {
        &self.content_transfer_encoding
    }
    pub fn is_html(&self) -> bool {
        self.content_type().0.is_text() && self.content_type().1.is_html()
    }
}

pub fn interpret_format_flowed(_t: &str) -> String {
    //let mut n = String::with_capacity(t.len());
    unimplemented!()
}

fn decode_rec_helper(a: &Attachment, filter: &Option<Box<Fn(&Attachment) -> Vec<u8>>>) -> Vec<u8> {
    if let Some(filter) = filter {
        return filter(a);
    }
    match a.attachment_type {
        AttachmentType::Data { .. } => { Vec::new()},
        AttachmentType::Text { .. } => decode_helper(a, filter),
        AttachmentType::Multipart {
            of_type: ref multipart_type,
            subattachments: ref sub_att_vec,
        } => if *multipart_type == MultipartType::Alternative {
            for a in sub_att_vec {
                if a.content_type.1 == ContentSubType::Plain {
                    return decode_helper(a, filter);
                }
            }
            decode_helper(a, filter)
        } else {
            let mut vec = Vec::new();
            for a in sub_att_vec {
                vec.extend(decode_rec_helper(a, filter));
                vec.extend_from_slice(b"\n\n");
            }
            vec
        },
    }
}
pub fn decode_rec(a: &Attachment, filter: Option<Box<Fn(&Attachment) -> Vec<u8>>>) -> Vec<u8> {
    decode_rec_helper(a, &filter)
}
fn decode_helper(a: &Attachment, filter: &Option<Box<Fn(&Attachment) -> Vec<u8>>>) -> Vec<u8> {
    if let Some(filter) = filter {
        return filter(a);
    }

    let charset = match a.content_type.0 {
        ContentType::Text{ charset: c } => c,
        _ => Default::default(),
    };

    let bytes = match a.content_transfer_encoding {
        ContentTransferEncoding::Base64 => match BASE64_MIME.decode(a.bytes()) {
            Ok(v) => v,
            _ => a.bytes().to_vec(),
        },
        ContentTransferEncoding::QuotedPrintable => parser::quoted_printable_bytes(a.bytes())
            .to_full_result()
            .unwrap(),
        ContentTransferEncoding::_7Bit
        | ContentTransferEncoding::_8Bit
        | ContentTransferEncoding::Other { .. } => a.bytes().to_vec(),
    };

    if a.content_type().0.is_text() {
        let decoded_result = parser::decode_charset(&bytes, charset);
        decoded_result.as_ref().map(|v| v.as_bytes()).unwrap_or_else(|_| a.bytes()).to_vec()
    } else {
        bytes.to_vec()
    }
}
pub fn decode(a: &Attachment, filter: Option<Box<Fn(&Attachment) -> Vec<u8>>>) -> Vec<u8> {
    decode_helper(a, &filter)
}