/*
 * meli - melib crate.
 *
 * Copyright 2017-2020 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 super::*;
use crate::backends::BackendOp;
use crate::email::attachments::AttachmentBuilder;
use crate::shellexpand::ShellExpandTrait;
use data_encoding::BASE64_MIME;
use std::collections::HashMap;
use std::ffi::OsStr;
use std::io::Read;
use std::path::{Path, PathBuf};
use std::str;

pub mod mime;
pub mod random;

//use self::mime::*;

use super::parser;

#[derive(Debug, PartialEq, Eq, Clone)]
pub struct Draft {
    pub headers: HashMap<String, String>,
    pub header_order: Vec<String>,
    pub body: String,

    pub attachments: Vec<AttachmentBuilder>,
}

impl Default for Draft {
    fn default() -> Self {
        let mut headers = HashMap::with_capacity_and_hasher(8, Default::default());
        let mut header_order = Vec::with_capacity(8);
        headers.insert("From".into(), "".into());
        headers.insert("To".into(), "".into());
        headers.insert("Cc".into(), "".into());
        headers.insert("Bcc".into(), "".into());

        headers.insert(
            "Date".into(),
            crate::datetime::timestamp_to_string(crate::datetime::now(), None),
        );
        headers.insert("Subject".into(), "".into());
        headers.insert(
            "User-Agent".into(),
            format!("meli {}", option_env!("CARGO_PKG_VERSION").unwrap_or("0.0")),
        );
        header_order.push("Date".into());
        header_order.push("From".into());
        header_order.push("To".into());
        header_order.push("Cc".into());
        header_order.push("Bcc".into());
        header_order.push("Subject".into());
        header_order.push("User-Agent".into());
        Draft {
            headers,
            header_order,
            body: String::new(),

            attachments: Vec::new(),
        }
    }
}

impl str::FromStr for Draft {
    type Err = MeliError;
    fn from_str(s: &str) -> Result<Self> {
        if s.is_empty() {
            return Err(MeliError::new("Empty input in Draft::from_str"));
        }

        let (headers, _) = parser::mail(s.as_bytes()).to_full_result()?;
        let mut ret = Draft::default();

        for (k, v) in headers {
            if ignore_header(k) {
                continue;
            }
            if ret
                .headers
                .insert(
                    String::from_utf8(k.to_vec())?,
                    String::from_utf8(v.to_vec())?,
                )
                .is_none()
            {
                ret.header_order.push(String::from_utf8(k.to_vec())?);
            }
        }
        if ret.headers.contains_key("From") && !ret.headers.contains_key("Message-ID") {
            if let super::parser::IResult::Done(_, addr) =
                super::parser::mailbox(ret.headers["From"].as_bytes())
            {
                if let Some(fqdn) = addr.get_fqdn() {
                    if ret
                        .headers
                        .insert("Message-ID".into(), random::gen_message_id(&fqdn))
                        .is_none()
                    {
                        let pos = ret
                            .header_order
                            .iter()
                            .position(|h| h == "Subject")
                            .unwrap();
                        ret.header_order.insert(pos, "Message-ID".into());
                    }
                }
            }
        }

        let body = Envelope::new(0).body_bytes(s.as_bytes());

        ret.body = String::from_utf8(decode(&body, None))?;

        Ok(ret)
    }
}

impl Draft {
    pub fn edit(envelope: &Envelope, mut op: Box<dyn BackendOp>) -> Result<Self> {
        let mut ret = Draft::default();
        //TODO: Inform user if error
        {
            let bytes = op.as_bytes().unwrap_or(&[]);
            for (k, v) in envelope.headers(bytes).unwrap_or_else(|_| Vec::new()) {
                if ignore_header(k.as_bytes()) {
                    continue;
                }
                if ret.headers.insert(k.into(), v.into()).is_none() {
                    ret.header_order.push(k.into());
                }
            }
        }

        ret.body = envelope.body(op)?.text();

        Ok(ret)
    }

    pub fn set_header(&mut self, header: &str, value: String) {
        if self.headers.insert(header.to_string(), value).is_none() {
            self.header_order.push(header.to_string());
        }
    }
    pub fn new_reply(envelope: &Envelope, bytes: &[u8]) -> Self {
        let mut ret = Draft::default();
        ret.headers_mut().insert(
            "References".into(),
            format!(
                "{} {}",
                envelope
                    .references()
                    .iter()
                    .fold(String::new(), |mut acc, x| {
                        if !acc.is_empty() {
                            acc.push(' ');
                        }
                        acc.push_str(&x.to_string());
                        acc
                    }),
                envelope.message_id_display()
            ),
        );
        ret.header_order.push("References".into());
        ret.headers_mut()
            .insert("In-Reply-To".into(), envelope.message_id_display().into());
        ret.header_order.push("In-Reply-To".into());
        if let Some(reply_to) = envelope.other_headers().get("Reply-To") {
            ret.headers_mut().insert("To".into(), reply_to.to_string());
        } else {
            ret.headers_mut()
                .insert("To".into(), envelope.field_from_to_string());
        }
        ret.headers_mut()
            .insert("Cc".into(), envelope.field_cc_to_string());
        let body = envelope.body_bytes(bytes);
        ret.body = {
            let reply_body_bytes = decode_rec(&body, None);
            let reply_body = String::from_utf8_lossy(&reply_body_bytes);
            let lines: Vec<&str> = reply_body.lines().collect();
            let mut ret = format!(
                "On {} {} wrote:\n",
                envelope.date_as_str(),
                ret.headers()["To"]
            );
            for l in lines {
                ret.push('>');
                ret.push_str(l);
                ret.push('\n');
            }
            ret.pop();
            ret
        };

        ret
    }

    pub fn headers_mut(&mut self) -> &mut HashMap<String, String> {
        &mut self.headers
    }

    pub fn headers(&self) -> &HashMap<String, String> {
        &self.headers
    }

    pub fn attachments(&self) -> &Vec<AttachmentBuilder> {
        &self.attachments
    }

    pub fn attachments_mut(&mut self) -> &mut Vec<AttachmentBuilder> {
        &mut self.attachments
    }

    pub fn body(&self) -> &str {
        &self.body
    }

    pub fn set_body(&mut self, s: String) {
        self.body = s;
    }

    pub fn to_string(&self) -> Result<String> {
        let mut ret = String::new();

        for k in &self.header_order {
            let v = &self.headers[k];
            ret.extend(format!("{}: {}\n", k, v).chars());
        }

        ret.push('\n');
        ret.push_str(&self.body);

        Ok(ret)
    }

    pub fn finalise(mut self) -> Result<String> {
        let mut ret = String::new();

        if self.headers.contains_key("From") && !self.headers.contains_key("Message-ID") {
            if let super::parser::IResult::Done(_, addr) =
                super::parser::mailbox(self.headers["From"].as_bytes())
            {
                if let Some(fqdn) = addr.get_fqdn() {
                    if self
                        .headers
                        .insert("Message-ID".into(), random::gen_message_id(&fqdn))
                        .is_none()
                    {
                        let pos = self
                            .header_order
                            .iter()
                            .position(|h| h == "Subject")
                            .unwrap();
                        self.header_order.insert(pos, "Message-ID".into());
                    }
                }
            }
        }
        for k in &self.header_order {
            let v = &self.headers[k];
            if v.is_ascii() {
                ret.extend(format!("{}: {}\n", k, v).chars());
            } else {
                ret.extend(format!("{}: {}\n", k, mime::encode_header(v)).chars());
            }
        }
        ret.push_str("MIME-Version: 1.0\n");

        if self.attachments.is_empty() {
            let content_type: ContentType = Default::default();
            let content_transfer_encoding: ContentTransferEncoding = ContentTransferEncoding::_8Bit;
            ret.extend(format!("Content-Type: {}; charset=\"utf-8\"\n", content_type).chars());
            ret.extend(
                format!("Content-Transfer-Encoding: {}\n", content_transfer_encoding).chars(),
            );
            ret.push('\n');
            ret.push_str(&self.body);
        } else if self.body.is_empty() && self.attachments.len() == 1 {
            let attachment = std::mem::replace(&mut self.attachments, Vec::new()).remove(0);
            print_attachment(&mut ret, &Default::default(), attachment);
        } else {
            let mut parts = Vec::with_capacity(self.attachments.len() + 1);
            let attachments = std::mem::replace(&mut self.attachments, Vec::new());
            if !self.body.is_empty() {
                let mut body_attachment = AttachmentBuilder::default();
                body_attachment.set_raw(self.body.as_bytes().to_vec());
                parts.push(body_attachment);
            }
            parts.extend(attachments.into_iter());
            build_multipart(&mut ret, MultipartType::Mixed, parts);
        }

        Ok(ret)
    }
}

fn ignore_header(header: &[u8]) -> bool {
    match header {
        b"From" => false,
        b"To" => false,
        b"Date" => false,
        b"Message-ID" => false,
        b"User-Agent" => false,
        b"Subject" => false,
        b"Reply-to" => false,
        b"Cc" => false,
        b"Bcc" => false,
        b"In-Reply-To" => false,
        b"References" => false,
        b"MIME-Version" => true,
        h if h.starts_with(b"X-") => false,
        _ => true,
    }
}

fn build_multipart(ret: &mut String, kind: MultipartType, parts: Vec<AttachmentBuilder>) {
    let boundary = ContentType::make_boundary(&parts);
    ret.extend(
        format!(
            "Content-Type: {}; charset=\"utf-8\"; boundary=\"{}\"\n",
            kind, boundary
        )
        .chars(),
    );
    ret.push('\n');
    /* rfc1341 */
    ret.extend("This is a MIME formatted message with attachments. Use a MIME-compliant client to view it properly.\n".chars());
    for sub in parts {
        ret.push_str("--");
        ret.extend(boundary.chars());
        ret.push('\n');
        print_attachment(ret, &kind, sub);
    }
    ret.push_str("--");
    ret.extend(boundary.chars());
    ret.push_str("--\n");
}

fn print_attachment(ret: &mut String, kind: &MultipartType, a: AttachmentBuilder) {
    use ContentType::*;
    match a.content_type {
        ContentType::Text {
            kind: crate::email::attachment_types::Text::Plain,
            charset: Charset::UTF8,
            parameters: ref v,
        } if v.is_empty() => {
            ret.push('\n');
            ret.push_str(&String::from_utf8_lossy(a.raw()));
            ret.push('\n');
        }
        Text { .. } => {
            ret.extend(a.build().into_raw().chars());
            ret.push('\n');
        }
        Multipart {
            boundary: _boundary,
            kind,
            parts: subparts,
        } => {
            build_multipart(
                ret,
                kind,
                subparts
                    .into_iter()
                    .map(|s| s.into())
                    .collect::<Vec<AttachmentBuilder>>(),
            );
            ret.push('\n');
        }
        MessageRfc822 | PGPSignature => {
            ret.extend(format!("Content-Type: {}; charset=\"utf-8\"\n", kind).chars());
            ret.push('\n');
            ret.push_str(&String::from_utf8_lossy(a.raw()));
            ret.push('\n');
        }
        _ => {
            let content_transfer_encoding: ContentTransferEncoding =
                ContentTransferEncoding::Base64;
            if let Some(name) = a.content_type().name() {
                ret.extend(
                    format!(
                        "Content-Type: {}; name=\"{}\"; charset=\"utf-8\"\n",
                        a.content_type(),
                        name
                    )
                    .chars(),
                );
            } else {
                ret.extend(
                    format!("Content-Type: {}; charset=\"utf-8\"\n", a.content_type()).chars(),
                );
            }
            ret.extend(
                format!("Content-Transfer-Encoding: {}\n", content_transfer_encoding).chars(),
            );
            ret.push('\n');
            ret.push_str(&BASE64_MIME.encode(a.raw()).trim());
            ret.push('\n');
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::str::FromStr;

    #[test]
    fn test_new() {
        let mut default = Draft::default();
        assert_eq!(
            Draft::from_str(&default.to_string().unwrap()).unwrap(),
            default
        );
        default.set_body("αδφαφσαφασ".to_string());
        assert_eq!(
            Draft::from_str(&default.to_string().unwrap()).unwrap(),
            default
        );
        default.set_body("ascii only".to_string());
        assert_eq!(
            Draft::from_str(&default.to_string().unwrap()).unwrap(),
            default
        );
    }

    #[test]
    fn test_attachments() {
        /*
        let mut default = Draft::default();
        default.set_body("αδφαφσαφασ".to_string());

        let mut file = std::fs::File::open("file path").unwrap();
        let mut contents = Vec::new();
        file.read_to_end(&mut contents).unwrap();

        let mut attachment = AttachmentBuilder::new(b"");
        attachment
            .set_raw(contents)
            .set_content_type(ContentType::Other {
                name: Some("images.jpeg".to_string()),
                tag: b"image/jpeg".to_vec(),
            })
            .set_content_transfer_encoding(ContentTransferEncoding::Base64);
        default.attachments_mut().push(attachment);
        println!("{}", default.finalise().unwrap());
        */
    }
}

/// Reads file from given path, and returns an 'application/octet-stream' AttachmentBuilder object
pub fn attachment_from_file<I>(path: &I) -> Result<AttachmentBuilder>
where
    I: AsRef<OsStr>,
{
    let path: PathBuf = Path::new(path).expand();
    if !path.is_file() {
        return Err(MeliError::new(format!("{} is not a file", path.display())));
    }

    let mut file = std::fs::File::open(&path)?;
    let mut contents = Vec::new();
    file.read_to_end(&mut contents)?;
    let mut attachment = AttachmentBuilder::default();
    attachment
        .set_raw(contents)
        .set_body_to_raw()
        .set_content_type(ContentType::Other {
            name: path.file_name().map(|s| s.to_string_lossy().into()),
            tag: b"application/octet-stream".to_vec(),
        });

    Ok(attachment)
}