OPML

use opml.qweruse opml_read, opml_feeds from opml      // Quillo 0.6: only these

opml = "1"

// A feed reader's import and export of subscriptions as OPML.////   quillo run opml.qwe      then open http://localhost:8080/importuse "opml.qwer"route GET /import = opml_feeds(read_file("opml_sample.opml")?)?route GET /tree {    let o = opml_read(read_file("opml_sample.opml")?)?    { title: o.title, folders: o.outlines | map((x) => { name: x.text, feeds: len(x.children) }) }}route GET /export.opml = respond(200, opml_write("Quillo Reader export", [    { title: "Quillo blog", xml_url: "https://quillolang.org/blog/feed.xml", html_url: "https://quillolang.org/blog/", category: "Programming" },    { title: "Example News", xml_url: "https://news.example.com/feed" },    { title: "This Week in Rust", xml_url: "https://this-week-in-rust.org/rss.xml", category: "Programming" },])?, { "content-type": "text/x-opml; charset=utf-8", "content-disposition": "attachment; filename=subscriptions.opml" })

//! OPML outlines read and written: the feed lists that RSS readers (Feedly, NetNewsWire, Inoreader) and podcast apps import and export, and other outlines.//! version: 1.0.0//!//! [dependencies]//! opml = "1"use opml::{Head, Outline, OPML};use serde_json::{json, Value};/// Files up to 10 MB are read.const MAX: usize = 10 * 1024 * 1024;fn doc(text: &str) -> Result<OPML, String> {    if text.len() > MAX {        return Err("OPML files up to 10 MB".into());    }    OPML::from_str(text).map_err(|e| format!("not OPML: {}", e))}/// An OPML text as `{ title, outlines }`: the head's title and the outline tree, each `{ text, title, type, xml_url,/// html_url, children }`.pub fn opml_read(text: &str) -> Result<Value, String> {    let d = doc(text)?;    Ok(json!({        "title": d.head.as_ref().and_then(|h| h.title.clone()),        "outlines": d.body.outlines.iter().map(|o| tree(o, 0)).collect::<Vec<_>>(),    }))}/// The feeds of an OPML subscription list, flat: `{ title, xml_url, html_url, category }` each, `category` being the folder/// they are in (null at the top). For importing a reader's export.pub fn opml_feeds(text: &str) -> Result<Vec<Value>, String> {    let d = doc(text)?;    let mut out = vec![];    for o in &d.body.outlines {        flat(o, None, &mut out, 0);    }    Ok(out)}/// An OPML subscription list titled `title` from `feeds` (`{ title, xml_url, html_url, category }`; `xml_url` needed), feeds/// with a `category` put in a folder of that name, in the order first met. Readers and podcast apps import it.pub fn opml_write(title: &str, feeds: Vec<serde_json::Value>) -> Result<String, String> {    let mut d = OPML::default();    d.head = Some(Head { title: Some(title.to_string()), ..Head::default() });    let mut folders: Vec<Outline> = vec![];    for (i, f) in feeds.iter().enumerate().take(100_000) {        let url = f["xml_url"].as_str().ok_or_else(|| format!("feed {} has no xml_url", i + 1))?;        let name = f["title"].as_str().unwrap_or(url).to_string();        let o = Outline {            text: name.clone(),            title: Some(name),            r#type: Some("rss".into()),            xml_url: Some(url.to_string()),            html_url: f["html_url"].as_str().map(str::to_string),            ..Outline::default()        };        match f["category"].as_str().filter(|c| !c.is_empty()) {            Some(cat) => match folders.iter_mut().find(|x| x.text == cat) {                Some(folder) => folder.outlines.push(o),                None => folders.push(Outline { text: cat.to_string(), title: Some(cat.to_string()), outlines: vec![o], ..Outline::default() }),            },            None => folders.push(o),        }    }    d.body.outlines = folders;    d.to_string().map_err(|e| e.to_string())}// The helpers that name the `type` field come last: Quillo's reader of .qwer files takes `r#` for the start of a raw// string, and would miss any `pub fn` written after it.fn tree(o: &Outline, depth: usize) -> Value {    json!({        "text": o.text,        "title": o.title,        "type": o.r#type,        "xml_url": o.xml_url,        "html_url": o.html_url,        "children": if depth < 50 { o.outlines.iter().map(|c| tree(c, depth + 1)).collect::<Vec<_>>() } else { vec![] },    })}fn flat(o: &Outline, category: Option<&str>, out: &mut Vec<Value>, depth: usize) {    if let Some(url) = &o.xml_url {        out.push(json!({ "title": o.title.clone().unwrap_or_else(|| o.text.clone()), "xml_url": url, "html_url": o.html_url, "category": category }));    }    if depth < 50 {        for c in &o.outlines {            // A folder's name is the category of the feeds inside it.            let cat = if o.xml_url.is_none() { Some(o.text.as_str()) } else { category };            flat(c, cat, out, depth + 1);        }    }}