translation.rs

use crate::error::{TranslateError, TranslateErrorKind};
use crate::fluent_bundle::FluentResource;
use crate::snippet::Style;
use crate::{DiagnosticArg, DiagnosticMessage, FluentBundle};
use fluent::FluentBundle as RawFluentBundle;
use md5::{Digest, Md5};
use rustc_data_structures::sync::Lrc;
use rustc_error_messages::FluentArgs;
use std::borrow::Cow;
use std::env;
use std::error::Report;
use unic_langid::langid;

/// Convert diagnostic arguments (a rustc internal type that exists to implement
/// `Encodable`/`Decodable`) into `FluentArgs` which is necessary to perform translation.
///
/// Typically performed once for each diagnostic at the start of `emit_diagnostic` and then
/// passed around as a reference thereafter.
pub fn to_fluent_args<'iter, 'arg: 'iter>(
    iter: impl Iterator<Item = DiagnosticArg<'iter, 'arg>>,
) -> FluentArgs<'arg> {
    let mut args = if let Some(size) = iter.size_hint().1 {
        FluentArgs::with_capacity(size)
    } else {
        FluentArgs::new()
    };

    for (k, v) in iter {
        args.set(k.clone(), v.clone());
    }

    args
}

pub trait Translate {
    /// Return `FluentBundle` with localized diagnostics for the locale requested by the user. If no
    /// language was requested by the user then this will be `None` and `fallback_fluent_bundle`
    /// should be used.
    fn fluent_bundle(&self) -> Option<&Lrc<FluentBundle>>;

    /// Return `FluentBundle` with localized diagnostics for the default locale of the compiler.
    /// Used when the user has not requested a specific language or when a localized diagnostic is
    /// unavailable for the requested locale.
    fn fallback_fluent_bundle(&self) -> &FluentBundle;

    /// Convert `DiagnosticMessage`s to a string, performing translation if necessary.
    fn translate_messages(
        &self,
        messages: &[(DiagnosticMessage, Style)],
        args: &FluentArgs<'_>,
    ) -> Cow<'_, str> {
        Cow::Owned(
            messages
                .iter()
                .map(|(m, _)| self.translate_message(m, args).map_err(Report::new).unwrap())
                .collect::<String>(),
        )
    }

    /// Convert a `DiagnosticMessage` to a string, performing translation if necessary.
    fn translate_message<'a>(
        &'a self,
        message: &'a DiagnosticMessage,
        args: &'a FluentArgs<'_>,
    ) -> Result<Cow<'_, str>, TranslateError<'_>> {
        trace!(?message, ?args);
        let (identifier, attr) = match message {
            DiagnosticMessage::Str(msg) | DiagnosticMessage::Eager(msg) => {
                return Ok(Cow::Borrowed(msg));
            }
            DiagnosticMessage::FluentRaw(msg) => {
                // FIXME(yukang): calculate the `slug` from the raw fluent content,
                // The fluent resources are generated by a simple standalone visitor:
                // https://github.com/chenyukang/fluent-utils/blob/main/src/visitor.rs#L13-L97
                // we may need to add fluent-utils into the tools directory of rustc
                let mut hasher = Md5::new();
                hasher.update(msg.to_string());
                let digest = hasher.finalize();
                let id = format!("{:x}", digest);
                let identifier = format!("slug-{}", id[0..8].to_string());
                let id = Cow::Borrowed(identifier.as_str());

                let translate_with_bundle =
                    |bundle: &'a FluentBundle| -> Result<Cow<'_, str>, TranslateError<'_>> {
                        let message = bundle
                            .get_message(&identifier)
                            .ok_or(TranslateError::message(&id, args))?;
                        let value = message.value().ok_or(TranslateError::value(&id, args))?;
                        debug!(?message, ?value);

                        let mut errs = vec![];
                        let translated = bundle.format_pattern(value, Some(args), &mut errs);
                        debug!(?translated, ?errs);
                        if errs.is_empty() {
                            Ok(translated)
                        } else {
                            Err(TranslateError::fluent(&id, args, errs))
                        }
                    };

                return {
                    match self.fluent_bundle().map(|b| translate_with_bundle(b)) {
                        // The primary bundle was present and translation succeeded
                        Some(Ok(t)) => {
                            // eprintln!("translated id OK: {} => {}", identifier, t);
                            Ok(t)
                        }

                        // If `translate_with_bundle` returns `Err` with the primary bundle, this is likely
                        // just that the primary bundle doesn't contain the message being translated, so
                        // proceed to the fallback bundle.
                        _ => {
                            // fallback to en-US, we don't need fluent bundle for raw fluent content in English
                            // here we just interpret the variables in the fluent content.
                            let fluent_text = format!("dummy = {}", msg);
                            if let Ok(resource) = FluentResource::try_new(fluent_text) {
                                let mut bundle = RawFluentBundle::new(vec![langid!("en-US")]);
                                bundle.add_resource(resource).unwrap();
                                let mut errors = vec![];
                                let pattern = bundle.get_message("dummy").unwrap().value().unwrap();
                                let res = bundle.format_pattern(&pattern, Some(args), &mut errors);
                                Ok(Cow::Owned(
                                    res.to_string().replace("\u{2068}", "").replace("\u{2069}", ""),
                                ))
                            } else {
                                Ok(Cow::Owned(msg.to_string()))
                            }
                        }
                    }
                };
            }
            DiagnosticMessage::FluentIdentifier(identifier, attr) => (identifier, attr),
        };
        // FIXME(yukang): remove this part for fluent resource id after all diagnostics are migrated to Fluent
        let translate_with_bundle =
            |bundle: &'a FluentBundle| -> Result<Cow<'_, str>, TranslateError<'_>> {
                let message = bundle
                    .get_message(identifier)
                    .ok_or(TranslateError::message(identifier, args))?;
                let value = match attr {
                    Some(attr) => message
                        .get_attribute(attr)
                        .ok_or(TranslateError::attribute(identifier, args, attr))?
                        .value(),
                    None => message.value().ok_or(TranslateError::value(identifier, args))?,
                };
                debug!(?message, ?value);

                let mut errs = vec![];
                let translated = bundle.format_pattern(value, Some(args), &mut errs);
                debug!(?translated, ?errs);
                if errs.is_empty() {
                    Ok(translated)
                } else {
                    Err(TranslateError::fluent(identifier, args, errs))
                }
            };

        try {
            match self.fluent_bundle().map(|b| translate_with_bundle(b)) {
                // The primary bundle was present and translation succeeded
                Some(Ok(t)) => t,

                // If `translate_with_bundle` returns `Err` with the primary bundle, this is likely
                // just that the primary bundle doesn't contain the message being translated, so
                // proceed to the fallback bundle.
                Some(Err(
                    primary @ TranslateError::One {
                        kind: TranslateErrorKind::MessageMissing, ..
                    },
                )) => translate_with_bundle(self.fallback_fluent_bundle())
                    .map_err(|fallback| primary.and(fallback))?,

                // Always yeet out for errors on debug (unless
                // `RUSTC_TRANSLATION_NO_DEBUG_ASSERT` is set in the environment - this allows
                // local runs of the test suites, of builds with debug assertions, to test the
                // behaviour in a normal build).
                Some(Err(primary))
                    if cfg!(debug_assertions)
                        && env::var("RUSTC_TRANSLATION_NO_DEBUG_ASSERT").is_err() =>
                {
                    do yeet primary
                }

                // ..otherwise, for end users, an error about this wouldn't be useful or actionable, so
                // just hide it and try with the fallback bundle.
                Some(Err(primary)) => translate_with_bundle(self.fallback_fluent_bundle())
                    .map_err(|fallback| primary.and(fallback))?,

                // The primary bundle is missing, proceed to the fallback bundle
                None => translate_with_bundle(self.fallback_fluent_bundle())
                    .map_err(|fallback| TranslateError::primary(identifier, args).and(fallback))?,
            }
        }
    }
}