//! One file per mail the app sends.
//!
//! Adding one means adding a module here and calling it — the wording never
//! leaks into the rest of the app, and changing a mail is a change to one file
//! with no logic in it. What every mail shares — the block of facts, the
//! signature, the frame — lives here so the six of them cannot drift apart.

pub mod reservation_approved;
pub mod reservation_bikes_changed;
pub mod reservation_cancelled;
pub mod reservation_period_changed;
pub mod reservation_shared;
pub mod reservation_updated;

use chrono::{DateTime, Utc};

use crate::core::models::reservation::Reservation;

/// Who to ask about anything the mail does not answer
const BOT_URL: &str = "https://t.me/Logistique_Agepoly_Bot";
const BOT_HANDLE: &str = "@Logistique_Agepoly_Bot";

/// The facts every mail about a reservation shows.
///
/// Built from the reservation as stored plus the names of the bikes it holds:
/// a mail reads nothing itself, so writing one is only a matter of words.
#[derive(Debug, Clone)]
pub struct ReservationSummary {
    pub id: i32,
    pub unit: String,
    pub start_time: DateTime<Utc>,
    pub end_time: DateTime<Utc>,
    pub bikes: Vec<String>,
}

impl ReservationSummary {
    pub fn new(reservation: &Reservation, bikes: Vec<String>) -> Self {
        ReservationSummary {
            id: reservation.id,
            unit: reservation.unit.label().to_owned(),
            start_time: reservation.start_time,
            end_time: reservation.end_time,
            bikes,
        }
    }

    pub fn period(&self) -> String {
        format!(
            "du {} au {}",
            format_moment(self.start_time),
            format_moment(self.end_time)
        )
    }

    pub fn bikes(&self) -> String {
        if self.bikes.is_empty() {
            "—".to_owned()
        } else {
            self.bikes.join(", ")
        }
    }

    /// The three lines every mail repeats, so the reader never has to look the
    /// reservation up to know which one is being talked about
    pub fn html_details(&self) -> String {
        format!(
            "<ul>\
             <li><strong>Association :</strong> {unit}</li>\
             <li><strong>Période :</strong> {period}</li>\
             <li><strong>Cargobikes réservés :</strong> {bikes}</li>\
             </ul>",
            unit = escape(&self.unit),
            period = escape(&self.period()),
            bikes = escape(&self.bikes()),
        )
    }

    pub fn text_details(&self) -> String {
        format!(
            "- Association : {}\n- Période : {}\n- Cargobikes réservés : {}",
            self.unit,
            self.period(),
            self.bikes()
        )
    }
}

/// The closing every mail ends on
pub fn signature_html() -> String {
    format!(
        "<p>Pour toute question, n'hésitez pas à contacter le bot logistique \
         <a href=\"{BOT_URL}\">{BOT_HANDLE}</a>.</p>\
         <p>Cordialement,<br>L'équipe AGEPoly.</p>"
    )
}

pub fn signature_text() -> String {
    format!(
        "Pour toute question, n'hésitez pas à contacter le bot logistique {BOT_HANDLE} \
         ({BOT_URL}).\n\nCordialement,\nL'équipe AGEPoly."
    )
}

/// The four characters an HTML body reads as markup
pub fn escape(value: &str) -> String {
    value
        .replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
        .replace('"', "&quot;")
}

/// Swiss local time, in the form the mails use
pub fn format_moment(moment: DateTime<Utc>) -> String {
    moment
        .with_timezone(&chrono::FixedOffset::east_opt(2 * 3600).expect("valid offset"))
        .format("%d/%m/%Y %H:%M")
        .to_string()
}

/// The plain frame every mail is poured into: a readable column, the system
/// font, and nothing a mail client has to fetch.
pub fn wrap(body: &str) -> String {
    format!(
        "<div style=\"font-family: -apple-system, 'Segoe UI', Roboto, Helvetica, Arial, sans-serif; \
         font-size: 15px; line-height: 1.5; color: #1a1a1a; max-width: 40rem;\">{body}</div>"
    )
}

#[cfg(test)]
pub mod tests {
    use chrono::TimeZone;

    use super::*;

    /// The fixture every mail test renders
    pub fn summary() -> ReservationSummary {
        ReservationSummary {
            id: 65,
            unit: "AGEPoly 2".to_owned(),
            start_time: Utc.with_ymd_and_hms(2026, 8, 18, 22, 0, 0).unwrap(),
            end_time: Utc.with_ymd_and_hms(2026, 8, 24, 22, 0, 0).unwrap(),
            bikes: vec!["3000".to_owned()],
        }
    }

    #[test]
    fn the_period_is_written_in_local_time() {
        // 22:00 UTC is midnight the next day in Lausanne
        assert_eq!(
            summary().period(),
            "du 19/08/2026 00:00 au 25/08/2026 00:00"
        );
    }

    #[test]
    fn markup_in_a_unit_name_is_escaped() {
        let mut summary = summary();
        summary.unit = "<b>Fake</b> & Co".to_owned();
        let details = summary.html_details();

        assert!(details.contains("&lt;b&gt;Fake&lt;/b&gt; &amp; Co"));
        assert!(details.contains("<strong>Association :</strong>"));
    }
}