vectorcraft/crates/ui-egui/src/print.rs

//! Printing through the platform. The host app installs a [`PrintService`] ([`crate::Services`]):
//! the desktop hands the job to the system's print spooler, the web to the browser's print dialog.
//! `file.print` with settings sends the engine's print-ready PDF (`file.print` in the engine) to
//! it, or saves the PDF when asked to (`toFile`, `path`) or when there is no print service; a
//! PostScript file (`format: "postscript"`, or a `.ps` path) is always saved. `print.printers`
//! lists the printers.

use serde::Serialize;
use serde_json::{Value, json};
use vectorcraft_engine::cmd::fileio;

use crate::{VectorcraftApp, io};

/// A printer the system knows.
#[derive(Clone, Debug, PartialEq, Serialize)]
pub struct Printer {
    pub name: String,
    /// The system's default printer.
    pub default: bool,
}

/// A print job: a print-ready PDF, every copy and page in it.
pub struct PrintJob<'a> {
    /// The printer; `None` = the system's default (the web: the browser's print dialog).
    pub printer: Option<&'a str>,
    /// The job's name in the print queue.
    pub title: &'a str,
    pub pdf: &'a [u8],
}

/// Submission callable from the desktop background worker.
pub type SharedPrintFn = std::sync::Arc<dyn Fn(&PrintJob<'_>) -> Result<String, String> + Send + Sync>;

/// The platform's printing ([`crate::Services::print`]).
pub trait PrintService {
    /// The printers the system knows (none: only the default one, or the browser's dialog).
    fn printers(&mut self) -> Vec<Printer>;
    /// Send `job` to its printer → what happened, for the status bar.
    fn print(&mut self, job: &PrintJob) -> Result<String, String>;
    /// Desktop services can submit on the existing background worker; browser services stay
    /// on the UI thread to invoke their print dialog.
    fn shared_print(&self) -> Option<SharedPrintFn> {
        None
    }
    /// Whether Setup… can open the system's printer settings.
    fn has_setup(&self) -> bool {
        false
    }
    /// Setup…: open the system's settings of `printer` (`None`: the printers).
    fn setup(&mut self, _printer: Option<&str>) -> Result<(), String> {
        Err("there are no printer settings to open here".into())
    }
}

/// `print.printers`: the system's printers, and what the print service offers.
pub fn printers(app: &mut VectorcraftApp) -> Value {
    let (printers, setup) = app.services.print.as_mut().map(|s| (s.printers(), s.has_setup())).unwrap_or_default();
    json!({ "printers": printers, "service": app.services.print.is_some(), "setup": setup })
}

/// `file.print` with settings: print the active document with `settings` (over the document's)
/// on `printer` (default: the system's default), or save the job as a PDF at `path` (else a picked
/// file, the web downloads it) with `toFile`, a `path` or no print service. A PostScript file
/// (`format: "postscript"` or a `.ps` path, at `level`, flattened with `flattenerPreset`) is saved
/// the same way.
pub fn run(app: &mut VectorcraftApp, p: &Value) -> Result<Value, String> {
    let s = |k: &str| p.get(k).and_then(Value::as_str).map(str::to_string);
    let postscript = s("format").as_deref() == Some("postscript") || s("path").is_some_and(|path| fileio::extension(&path) == "ps");
    let to_file = p.get("toFile").and_then(Value::as_bool).unwrap_or(false) || s("path").is_some() || postscript;
    let mut q = json!({});
    for k in ["settings", "format", "level", "flattenerPreset"] {
        if let Some(v) = p.get(k).filter(|v| !v.is_null()) {
            q[k] = v.clone();
        }
    }
    if postscript {
        // The path is taken off before the engine runs: it can't tell the format from it.
        q["format"] = json!("postscript");
    }
    if to_file || app.services.print.is_none() {
        if let Some(path) = s("path") {
            q["path"] = json!(path);
        }
        let (path, mut v) = io::run_to_file(app, "file.print", if postscript { "ps" } else { "pdf" }, q)?;
        io::report_saved(app, &path, &v);
        if !to_file {
            app.ui.status.push_str(" (printing isn't available here: the job was saved as a PDF)");
        }
        v["path"] = json!(path);
        v["printed"] = json!(false);
        return Ok(v);
    }
    let mut v = app.session.execute("file.print", &q).map_err(|e| e.to_string())?;
    let data = v.as_object_mut().and_then(|o| o.remove("dataBase64"));
    let pdf = data.as_ref().and_then(Value::as_str).and_then(vectorcraft_format::base64_decode).ok_or("the print job has no data")?;
    let title = app.session.active().map(|d| d.title()).unwrap_or_default();
    let printer = s("printer").filter(|n| !n.is_empty());
    let service = app.services.print.as_mut().ok_or("no print service")?;
    if let Some(submit) = service.shared_print() {
        let pending_printer = printer.clone();
        let mut pending = crate::background::run(
            app,
            true,
            format!("Printing {title}"),
            None,
            move |_| {
                submit(&PrintJob { printer: printer.as_deref(), title: &title, pdf: &pdf }).map(|note| json!({ "note": note, "printer": printer }))
            },
            move |app, result| {
                let receipt = result?;
                app.status(receipt.get("note").and_then(Value::as_str).unwrap_or_default());
                Ok(json!({ "printer": receipt["printer"], "printed": true }))
            },
        )?;
        if pending.get("background").and_then(Value::as_bool) == Some(true) {
            // Acceptance by the worker is not acceptance by the spooler.
            pending["printer"] = json!(pending_printer);
            pending["printed"] = json!(false);
        }
        // Preserve the engine's pages, byte count, format and warnings in automation replies.
        if let Some(fields) = pending.as_object() {
            for (key, value) in fields {
                v[key] = value.clone();
            }
        }
        return Ok(v);
    }
    let done = service.print(&PrintJob { printer: printer.as_deref(), title: &title, pdf: &pdf })?;
    app.status(done);
    v["printer"] = json!(printer);
    v["printed"] = json!(true);
    Ok(v)
}