path: root/_invitation-mailer/src/main.rs

use {
    anyhow::{
        anyhow,
        Context,
        Result,
    },
    chrono::{
        DateTime,
        Local,
        TimeZone,
        Utc,
    },
    getopts::Options,
    ics::{
        escape_text,
        Event,
        ICalendar,
        properties::{
            Description,
            DtEnd,
            DtStart,
            Location,
            Organizer,
            Summary,
        },
    },
    emailmessage::{
        header,
        Message,
        MultiPart,
        SinglePart,
    },
    lettre::{
        address::Envelope,
        SmtpTransport,
        Transport,
        transport::smtp::authentication::Credentials,
    },
    minijinja::{
        Environment,
        context as jinja_context,
    },
    nos::Document,
    std::{
        env::args,
        fs::File,
        io::Read,
    },
    uuid::Uuid,
};

fn print_usage(program: &str, opts: Options) {
    let brief = format!("Usage: {} [options] 'Recipient name <recipient@email.address>'", program);
    print!("{}", opts.usage(&brief));
}

fn to_iso8601(dt: DateTime<Local>) -> String {
    // https://github.com/chronotope/chrono/issues/244
    DateTime::<Utc>::from(dt).format("%Y%m%dT%H%M%SZ").to_string()
}

fn month_number(month: &str) -> Result<u32> {
   match month {
        "January" => Ok(1),
        "February" => Ok(2),
        "March" => Ok(3),
        "April" => Ok(4),
        "May" => Ok(5),
        "June" => Ok(6),
        "July" => Ok(7),
        "August" => Ok(8),
        "September" => Ok(9),
        "October" => Ok(10),
        "November" => Ok(11),
        "December" => Ok(12),
        invalid => Err(anyhow!("Invalid month name: {invalid}")),
    }
}

struct Desc {
    _html: String,
    plain: String,
}

struct HackNight {
    title: String,
    desc: Desc,
    start: DateTime<Local>,
    end: DateTime<Local>,
    location: String,
}

impl HackNight {
    fn new(
        title: String,
        desc: Desc,
        start: DateTime<Local>,
        end: DateTime<Local>,
        location: String,
    ) -> Self {
        Self {
            title,
            desc,
            start,
            end,
            location,
        }
    }

    fn from_html(filename: &str) -> Result<HackNight> {
        let mut file = File::open(filename)?;
        let mut html = String::new();
        File::read_to_string(&mut file, &mut html)?;
        let document = Document::from(&html);
        let event = document.select("article.event").iter().next()
            .ok_or_else(|| anyhow!("Could not find event in html file"))?;

        let year = event.select("p.event-year").text().to_string().parse::<i32>()?;
        let month = month_number(event.select("p.event-month").text().to_string().as_str())?;
        let day = event.select("p.event-day").text().to_string().parse::<u32>()?;

        let timespan = event.select("dl.dl-horizontal > dd").iter().last()
            .ok_or_else(|| anyhow!("No venue timespan found"))?.text().to_string();
        let (start_str, end_str) = timespan.split_once('—')
            .ok_or_else(|| anyhow!("Couldn't split timespan"))?;
        let start_hh = start_str[0..=1].parse::<u32>()?;
        let start_mm = start_str[3..=4].parse::<u32>()?;
        let end_hh: u32 = end_str[0..=1].parse()?;
        let end_mm: u32 = end_str[3..=4].parse()?;

        let description = event.select("div.event-desc");
        let title = event.select("h3.event-desc-header").text().to_string().trim().to_owned();

        let mut title_elem = event.select("h3.event-desc-header");
        title_elem.remove();

        let location = event.select("dl.dl-horizontal > dd > strong").iter().next()
            .ok_or_else(|| anyhow!("No venue location found"))?.text().to_string();
        let mut horizontals = event.select("dl.dl-horizontal");
        horizontals.remove();

        let desc = Desc {
            _html: description.html().to_string(),
            plain: august::convert_unstyled(&description.html().to_string(), 79),
        };

        let start = Local.ymd(year, month, day).and_hms(start_hh, start_mm, 0);
        let end = Local.ymd(year, month, day).and_hms(end_hh, end_mm, 0);

        Ok(HackNight::new(title, desc, start, end, location))
    }

    fn ics<'a>(&'a self, organizer: &str) -> Result<ICalendar<'a>> {
        let mut calendar = ICalendar::new("2.0", "-//cph.rs//Hack Night inviter//EN");
        let uuid = Uuid::new_v4().to_string();
        let timestamp = to_iso8601(Local::now());

        let mut event = Event::new(uuid, timestamp);

        event.push(Organizer::new(format!("mailto:{organizer}")));
        event.push(DtStart::new(to_iso8601(self.start)));
        event.push(DtEnd::new(to_iso8601(self.end)));
        event.push(Summary::new(format!("Rust {}", self.title)));
        event.push(Location::new(self.location.clone()));
        event.push(Description::new(escape_text(self.desc.plain.clone())));

        calendar.add_event(event);

        Ok(calendar)
    }

    fn mail_body(&self, fields: &Input) -> Result<String> {
        let mut file = File::open(fields.template.clone())?;
        let mut contents = String::new();
        File::read_to_string(&mut file, &mut contents)?;
        let mut env = Environment::new();
        env.add_template("plain/text", &contents)?;
        let template = env.get_template("plain/text")?;

        template.render(jinja_context! {
            body => self.desc.plain,
            organizer_email => fields.organizer_email,
        }).context("jinja")
    }

    fn mime_message(&self, input: &Input, body: &str, ics: &ICalendar)
        -> Result<Message<MultiPart<String>>>
    {
        Ok(Message::builder()
            .from(format!("{} <{}>", input.sender_name, input.sender_email).parse()?)
            .to(format!("{} <{}>", input.recipient_name, input.recipient_email).parse()?)
            .subject(format!("Rust {}", &self.title))
            .mime_body(
                MultiPart::mixed()
                .singlepart(
                    SinglePart::quoted_printable()
                    .header(header::ContentType("text/plain; charset=utf8".parse()?))
                    .body(String::from(body))
                )
                .singlepart(
                    SinglePart::base64()
                    .header(header::ContentType("text/calendar; charset=utf8".parse()?))
                    .body(format!("{}", ics))
                )
            )
        )
    }
}

struct Input {
    sender_name: String,
    sender_email: String,
    recipient_name: String,
    recipient_email: String,
    _organizer_name: String,
    organizer_email: String,
    template: String,
}

fn main() -> Result<()> {
    let args: Vec<String> = args().collect();
    let program = args[0].clone();

    let mut opts = Options::new();
    opts.optopt("", "smtp-username", "", "");
    opts.optopt("", "smtp-password", "", "");
    opts.optopt("", "smtp-server", "", "");
    opts.optopt("", "sender-name", "", "Remember to quote spaces");
    opts.optopt("", "sender-email", "", "");
    opts.optopt("", "organizer-name", "", "(Never actually used)");
    opts.optopt("", "organizer-email", "", "");
    opts.optopt("", "jekyll-input-file", "../index.html", "");
    opts.optopt("", "email-template", "email_body.j2", "");
    opts.optflag("h", "help", "Print this help text");
    let matches = opts.parse(&args[1..])?;
    if matches.opt_present("h") {
        print_usage(&program, opts);
        return Ok(());
    }
    let (recipient_name, recipient_email) = if !matches.free.is_empty() {
        matches.free[0].strip_suffix('>')
            .ok_or_else(|| anyhow!("Could not understand recipient argument"))?.split_once(" <")
            .ok_or_else(|| anyhow!("Could not understand recipient argument"))?
    } else {
        print_usage(&program, opts);
        return Ok(());
    };

    let input = Input {
        sender_name: matches.opt_str("sender-name").ok_or_else(|| anyhow!("Missing sender name"))?,
        sender_email: matches.opt_str("sender-email")
            .ok_or_else(|| anyhow!("Missing sender email"))?,
        _organizer_name: matches.opt_str("organizer-name").unwrap_or_default(),
        organizer_email: matches.opt_str("organizer-email")
            .ok_or_else(|| anyhow!("Missing organizer email"))?,
        recipient_name: String::from(recipient_name),
        recipient_email: String::from(recipient_email),
        template: matches.opt_str("email-template")
            .unwrap_or_else(|| String::from("email_body.j2")),
    };
    let hacknight = HackNight::from_html(&matches.opt_str("jekyll-input-file")
        .unwrap_or_else(|| String::from("../index.html")))?;

    let calendar = hacknight.ics(&input.organizer_email)?;
    let body = hacknight.mail_body(&input)?;

    let email = hacknight.mime_message(&input, &body, &calendar)?;

    let creds = Credentials::new(
        matches.opt_str("smtp-username").ok_or_else(|| anyhow!("Missing smtp username"))?,
        matches.opt_str("smtp-password").ok_or_else(|| anyhow!("Missing smtp password"))?,
    );

    // let mailer = SmtpTransport::relay(
    let mailer = SmtpTransport::starttls_relay(
        &matches.opt_str("smtp-server").ok_or_else(|| anyhow!("Missing smtp server"))?
    )?.credentials(creds).build();

    let envelope = Envelope::new(Some(input.sender_email.parse()?),
        vec![input.recipient_email.parse()?])?;
    mailer.send_raw(&envelope, format!("{}", &email).as_bytes()).map(|_| ())
        .context("Failed to send email message")
}