//! fig2dev in the engine (`fig2dev`, a program of its own that
//! RustFig depends on, plan B12):
//!
//! - Every export goes through fig2dev: the document's objects, as fig2dev's
//!   reader would return them for the saved Fig 3.2 text, go straight to
//!   the language's driver with fig2dev's options ([`export`]); where the
//!   reader would print a message or refuse the file, the text is written
//!   and read ([`export_via_text`], as xfig hands a figure to fig2dev). A
//!   language is available as soon as `fig2dev::drivers::driver` provides
//!   it; the combined LaTeX exports (`pstex`, `pdftex`, `pspdftex`) need
//!   both halves.
//! - Every Fig file (1.3 to 3.2) opens through fig2dev's reader, converted by
//!   `rustfig_format::bridge` (`rustfig_format::read_any`).
//! - Pictures as fig2dev reads them (`readpics.c`), where the `image`
//!   crate can't.
//!
//! fig2dev's language and option tables are re-exported here
//! ([`languages`], [`options`]) for the export dialog and the CLI.

pub use fig2dev::util::pdfpic::PdfPicture;
pub use fig2dev::util::readpics::LoadedPicture;
pub use fig2dev::{languages, options};

use fig2dev::object::Compound;
use fig2dev::{read, Ctx, Driver};
use languages::Language;
use rustfig_model::Document;
use std::path::Path;

/// Whether the fig2dev crate writes language `id` (fig2dev's name).
pub fn driver_available(id: &str) -> bool {
    fig2dev::drivers::driver(id).is_some()
}

/// Whether RustFig can export `lang`: fig2dev's driver for it is ported
/// (for the combined languages, the drivers of both halves).
pub fn language_available(lang: &Language) -> bool {
    match lang.id {
        "pstex" => driver_available("pstex") && driver_available("pstex_t"),
        "pdftex" => driver_available("pdftex") && driver_available("pdftex_t"),
        "pspdftex" => driver_available("pstex") && driver_available("pdftex") && driver_available("pstex_t"),
        "pspdf" => driver_available("eps") && driver_available("pdf"),
        id => driver_available(id),
    }
}

/// Export `doc` with fig2dev's driver for `lang` (fig2dev's `-L` name):
/// `options` are fig2dev's option letters and arguments, in order (general
/// ones too); `dir` is where relative picture names are found. The output
/// and fig2dev's messages (its warnings); fig2dev's errors are `Err`.
///
/// The drivers get the objects straight from the document
/// ([`rustfig_format::bridge::export_objects`]), the same as through
/// [`export_via_text`] (plan D7); where the Fig file would make fig2dev's
/// reader say something or read it differently, the text path runs.
pub fn export(
    doc: &Document,
    lang: &str,
    options: &[(char, Option<String>)],
    dir: Option<&Path>,
) -> Result<(Vec<u8>, Vec<String>), String> {
    let (mut dev, mut ctx) = setup(lang, options, dir)?;
    match rustfig_format::bridge::export_objects(doc, &mut ctx) {
        Some(objects) => finish(lang, dev.as_mut(), &mut ctx, &objects),
        None => export_via_text(doc, lang, options, dir),
    }
}

/// [`export`] the way xfig does it: the document written as Fig 3.2 text
/// and read by fig2dev's reader. The reference for [`export`].
pub fn export_via_text(
    doc: &Document,
    lang: &str,
    options: &[(char, Option<String>)],
    dir: Option<&Path>,
) -> Result<(Vec<u8>, Vec<String>), String> {
    let (mut dev, mut ctx) = setup(lang, options, dir)?;
    let fig = rustfig_format::write_fig(doc);
    let objects = read::readfp_fig(&mut ctx, fig.as_bytes()).map_err(|_| ctx.messages.join("\n"))?;
    finish(lang, dev.as_mut(), &mut ctx, &objects)
}

/// The driver and the context with fig2dev's options applied.
fn setup(lang: &str, options: &[(char, Option<String>)], dir: Option<&Path>) -> Result<(Box<dyn Driver>, Ctx), String> {
    let mut dev = fig2dev::drivers::driver(lang).ok_or_else(|| format!("no fig2dev driver for {lang}"))?;
    let mut ctx = Ctx {
        lang: lang.to_string(),
        dir: dir.map(Path::to_path_buf),
        ..Ctx::default()
    };
    let l = Some(lang.to_string());
    for (c, arg) in std::iter::once(&('L', l)).chain(options) {
        let arg = arg.as_deref();
        if !ctx.general_option(*c, arg)? {
            dev.option(&mut ctx, *c, arg)?;
        }
    }
    // After the options, so that -m counts (fig2dev's get_args).
    ctx.font_size *= ctx.fontmag;
    Ok((dev, ctx))
}

fn finish(
    lang: &str,
    dev: &mut dyn Driver,
    ctx: &mut Ctx,
    objects: &Compound,
) -> Result<(Vec<u8>, Vec<String>), String> {
    let status = fig2dev::convert(ctx, dev, objects)?;
    let messages = std::mem::take(&mut ctx.messages);
    if status.exit != 0 && status.output.is_empty() {
        return Err(if messages.is_empty() {
            format!("fig2dev's {lang} driver failed")
        } else {
            messages.join("\n")
        });
    }
    Ok((status.output, messages))
}

/// Read picture `path` as fig2dev does (`.gz`/`.Z` variants, XBM, XPM,
/// PCX, EPS, PDF and the common bitmaps).
pub fn load_picture(path: &Path) -> Result<LoadedPicture, String> {
    fig2dev::util::readpics::load_picture(&mut Ctx::default(), &path.to_string_lossy())
}

/// An EPS file as a PDF page by ghostscript, when it is installed (B15;
/// fig2dev's `util::gs`: `gs` on `PATH`, no shell, time and size limits).
#[cfg(not(target_arch = "wasm32"))]
pub fn gs_eps_to_pdf(eps: &[u8]) -> Result<std::sync::Arc<Vec<u8>>, String> {
    fig2dev::util::gs::eps_to_pdf(eps)
}

/// fig2dev's command line (`fig2dev::cli::run`) on the process's stdin,
/// stdout and stderr: what `fig2dev ARGS…` does, reached as
/// `rustfig fig2dev ARGS…`, `rustfig-cli fig2dev ARGS…` or by starting
/// the program under the name `fig2dev` (plan DD10). Returns the exit
/// status. Not on wasm (no process streams).
#[cfg(not(target_arch = "wasm32"))]
pub fn run_cli(args: Vec<String>) -> u8 {
    fig2dev::cli::run(
        args,
        &mut std::io::stdin().lock(),
        &mut std::io::stdout().lock(),
        &mut std::io::stderr().lock(),
    )
}

/// The process arguments after the program name, as fig2dev reads them
/// (not UTF-8 is read lossily rather than aborting).
#[cfg(not(target_arch = "wasm32"))]
pub fn process_args() -> Vec<String> {
    std::env::args_os()
        .skip(1)
        .map(|a| a.to_string_lossy().into_owned())
        .collect()
}

/// True when the program was started under the name `fig2dev` (a link or
/// copy of the RustFig binary): `argv[0]`'s file stem is `fig2dev`, so
/// `fig2dev.exe` on Windows counts too.
#[cfg(not(target_arch = "wasm32"))]
pub fn started_as_fig2dev() -> bool {
    std::env::args_os().next().is_some_and(|a| is_fig2dev_name(&a))
}

/// `argv[0]` names fig2dev: its file stem is `fig2dev` (case-insensitive,
/// for Windows).
pub fn is_fig2dev_name(argv0: &std::ffi::OsStr) -> bool {
    // Both separators, whatever the platform: argv[0] may come from either.
    let s = argv0.to_string_lossy();
    let base = s.rsplit(['/', '\\']).next().unwrap_or("");
    let stem = base
        .strip_suffix(".exe")
        .or_else(|| base.strip_suffix(".EXE"))
        .unwrap_or(base);
    stem.eq_ignore_ascii_case("fig2dev")
}

#[cfg(test)]
mod name_tests {
    use super::is_fig2dev_name;
    use std::ffi::OsStr;

    #[test]
    fn program_names() {
        for yes in ["fig2dev", "/usr/local/bin/fig2dev", "C:\\x\\fig2dev.exe", "fig2dev.EXE"] {
            assert!(is_fig2dev_name(OsStr::new(yes)), "{yes}");
        }
        for no in [
            "rustfig",
            "rustfig-cli",
            "fig2dev-cli",
            "xfig2dev",
            "",
            "/a/fig2dev/rustfig",
        ] {
            assert!(!is_fig2dev_name(OsStr::new(no)), "{no}");
        }
    }
}