Build translations from mdbook

i18n-helpers/Cargo.toml

@@ -18,6 +18,7 @@ pulldown-cmark = { version = "0.9.2", default-features = false }
 pulldown-cmark-to-cmark = "11.0.0"
 regex = "1.9.4"
 semver = "1.0.16"
+serde = "1.0.130"
 serde_json = "1.0.91"
 
 [dev-dependencies]

i18n-helpers/src/bin/mdbook-i18n.rs

@@ -0,0 +1,105 @@
+use anyhow::{anyhow, Result};
+use mdbook::renderer::RenderContext;
+use serde::Deserialize;
+use std::collections::BTreeMap;
+use std::io;
+
+/// Parameters for the i18n renderer.
+///
+/// They are set in the `output.i18n` section of the book's `book.toml` file.
+#[derive(Deserialize)]
+struct I18nConfiguration {
+    /// A map of language codes to language names.
+    ///
+    /// ## Example
+    ///
+    /// ```toml
+    /// [output.i18n.languages]
+    /// "en" = "English"
+    /// "es" = "Spanish (Español)"
+    /// "ko" = "Korean (한국어)"
+    /// "pt-BR" = "Brazilian Portuguese (Português do Brasil)"
+    /// ```
+    #[serde(default)]
+    languages: BTreeMap<String, String>,
+    /// Default language code. It will not be translated.
+    default_language: Option<String>,
+
+    /// Whether to translate all languages or just the selected language in `mdbook.config.book.language`, defaults to false.
+    #[serde(default)]
+    translate_all_languages: bool,
+    /// Whether to move the translations to their renderer's directory, defaults to false.
+    ///
+    /// By default, translations' output will live in `book/i18n/<language>/<renderer>`.
+    /// For all renderers in this list, we will move individual translations to `book/<renderer>/<language>`.
+    #[serde(default)]
+    move_translations_directories: Vec<String>,
+}
+
+fn main() -> Result<()> {
+    let mut stdin = io::stdin();
+
+    // Get the configs
+    let ctx = RenderContext::from_json(&mut stdin)?;
+    let i18n_config: I18nConfiguration = ctx
+        .config
+        .get_deserialized_opt("output.i18n")?
+        .ok_or_else(|| anyhow!("No output.i18n config in book.toml"))?;
+
+    if !i18n_config.translate_all_languages {
+        return Ok(());
+    }
+
+    let mut mdbook = mdbook::MDBook::load(&ctx.root)?;
+    // Overwrite with current values from stdin. This is necessary because mdbook will add data to the config.
+    mdbook.book = ctx.book.clone();
+    mdbook.config = ctx.config.clone();
+    mdbook.root = ctx.root.clone();
+
+    let book_config = mdbook
+        .config
+        .get_mut("output.i18n")
+        .ok_or_else(|| anyhow!("No output.i18n config in book.toml"))?;
+    // Set translate_all_languages to false for nested builds to prevent infinite recursion.
+    book_config
+        .as_table_mut()
+        .ok_or_else(|| anyhow!("output.i18n config in book.toml is not a table"))?
+        .insert(String::from("translate_all_languages"), false.into());
+
+    let output_directory = ctx.destination;
+    let default_language = &i18n_config.default_language;
+
+    for language in i18n_config.languages.keys() {
+        // Skip current language and default language.
+        if Some(language) == ctx.config.book.language.as_ref() {
+            continue;
+        }
+        if default_language.as_ref() == Some(language) {
+            continue;
+        }
+        let translation_path = output_directory.join(language);
+
+        // Book doesn't implement clone, so we just mutate in place.
+        mdbook.config.book.language = Some(language.clone());
+        mdbook.config.book.multilingual = true;
+        mdbook.config.build.build_dir = translation_path;
+        mdbook.build()?;
+        for renderer in &i18n_config.move_translations_directories {
+            std::fs::create_dir_all(
+                output_directory
+                    .parent()
+                    .ok_or_else(|| anyhow!("Failed to retrieve parent directory"))?
+                    .join(renderer),
+            )?;
+            std::fs::rename(
+                output_directory.join(language).join(renderer),
+                output_directory
+                    .parent()
+                    .ok_or_else(|| anyhow!("Failed to retrieve parent directory"))?
+                    .join(renderer)
+                    .join(language),
+            )?;
+        }
+    }
+    Ok(())
+}