//! IPTV export: M3U playlist and XMLTV guide generation.
//!
//! Pure functions — no I/O, no dependencies beyond domain types.

use std::collections::HashMap;

use crate::entities::{Channel, ScheduledSlot};
use crate::value_objects::ChannelId;

/// Generate an M3U playlist for the given channels.
///
/// Each entry points to the channel's `/stream` endpoint authenticated with the
/// provided JWT token so IPTV clients can load it directly.
pub fn generate_m3u(channels: &[Channel], base_url: &str, token: &str) -> String {
    let mut out = String::from("#EXTM3U\n");
    for ch in channels {
        out.push_str(&format!(
            "#EXTINF:-1 tvg-id=\"{}\" tvg-name=\"{}\" tvg-logo=\"\" group-title=\"K-TV\",{}\n",
            ch.id, ch.name, ch.name
        ));
        out.push_str(&format!(
            "{}/api/v1/channels/{}/stream?token={}\n",
            base_url, ch.id, token
        ));
    }
    out
}

/// Generate an XMLTV EPG document for the given channels and their scheduled slots.
pub fn generate_xmltv(
    channels: &[Channel],
    slots_by_channel: &HashMap<ChannelId, Vec<ScheduledSlot>>,
) -> String {
    let mut out =
        String::from("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<tv generator-info-name=\"k-tv\">\n");

    for ch in channels {
        out.push_str(&format!(
            "  <channel id=\"{}\"><display-name>{}</display-name></channel>\n",
            ch.id,
            escape_xml(&ch.name)
        ));
    }

    for ch in channels {
        if let Some(slots) = slots_by_channel.get(&ch.id) {
            for slot in slots {
                let start = slot.start_at.format("%Y%m%d%H%M%S +0000");
                let stop = slot.end_at.format("%Y%m%d%H%M%S +0000");
                out.push_str(&format!(
                    "  <programme start=\"{}\" stop=\"{}\" channel=\"{}\">\n",
                    start, stop, ch.id
                ));
                out.push_str(&format!(
                    "    <title lang=\"en\">{}</title>\n",
                    escape_xml(&slot.item.title)
                ));
                if let Some(desc) = &slot.item.description {
                    out.push_str(&format!(
                        "    <desc lang=\"en\">{}</desc>\n",
                        escape_xml(desc)
                    ));
                }
                if let Some(genre) = slot.item.genres.first() {
                    out.push_str(&format!(
                        "    <category lang=\"en\">{}</category>\n",
                        escape_xml(genre)
                    ));
                }
                if let (Some(season), Some(episode)) =
                    (slot.item.season_number, slot.item.episode_number)
                {
                    out.push_str(&format!(
                        "    <episode-num system=\"onscreen\">S{}E{}</episode-num>\n",
                        season, episode
                    ));
                }
                out.push_str("  </programme>\n");
            }
        }
    }

    out.push_str("</tv>\n");
    out
}

fn escape_xml(s: &str) -> String {
    s.replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
        .replace('"', "&quot;")
        .replace('\'', "&apos;")
}