microsoft-webui-parser 0.0.19

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT license.

//! Link-mode CSS filename and public href resolution.

use crate::{AssetFileNameTemplate, ParserError, Result, DEFAULT_ASSET_FILE_NAME_TEMPLATE};
use std::collections::HashMap;
use std::sync::{Arc, Mutex};

/// Default Link-mode CSS filename template.
pub const DEFAULT_CSS_FILE_NAME_TEMPLATE: &str = DEFAULT_ASSET_FILE_NAME_TEMPLATE;

/// Configures Link-mode CSS filenames and public hrefs.
#[derive(Debug, Clone)]
pub struct CssLinkOptions {
    file_name_template: AssetFileNameTemplate,
    public_base: Option<String>,
    cache: Arc<Mutex<HashMap<String, CssLinkHref>>>,
}

/// Resolved Link-mode CSS asset path data.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct CssLinkHref {
    /// Local filename emitted by build output.
    pub filename: String,
    /// Public href used in parser/handler `<link>` tags.
    pub href: String,
}

impl CssLinkOptions {
    /// Create validated Link-mode CSS options.
    ///
    /// # Errors
    ///
    /// Returns [`ParserError::Css`] when the template contains unknown tokens,
    /// unsafe path bytes, or an unsafe public base.
    pub fn try_new(file_name_template: String, public_base: Option<String>) -> Result<Self> {
        let file_name_template =
            AssetFileNameTemplate::try_new(file_name_template, "css_file_name_template")
                .map_err(|error| ParserError::Css(error.to_string()))?;
        if let Some(base) = public_base.as_deref() {
            validate_css_public_base(base)?;
        }
        Ok(Self {
            file_name_template,
            public_base,
            cache: Arc::new(Mutex::new(HashMap::new())),
        })
    }

    /// Resolve the local filename and public href for a component stylesheet.
    ///
    /// Results are cached by component tag. A `CssLinkOptions` value should be
    /// scoped to one build/component registry where each tag maps to exactly
    /// one stylesheet.
    #[must_use]
    pub fn resolve(&self, tag_name: &str, css_content: &str) -> CssLinkHref {
        {
            let cache = self
                .cache
                .lock()
                .unwrap_or_else(std::sync::PoisonError::into_inner);
            if let Some(cached) = cache.get(tag_name) {
                return cached.clone();
            }
        }

        let filename = self
            .file_name_template
            .resolve(tag_name, "css", css_content.as_bytes());
        let href = match self.public_base.as_deref() {
            Some(base) => join_css_public_base(base, &filename),
            None => filename.clone(),
        };
        let resolved = CssLinkHref { filename, href };

        let mut cache = self
            .cache
            .lock()
            .unwrap_or_else(std::sync::PoisonError::into_inner);
        cache
            .entry(tag_name.to_string())
            .or_insert_with(|| resolved.clone())
            .clone()
    }

    /// File name template used for Link-mode CSS files.
    #[must_use]
    pub fn file_name_template(&self) -> &str {
        self.file_name_template.file_name_template()
    }

    /// Optional public base prepended to Link-mode CSS hrefs.
    #[must_use]
    pub fn public_base(&self) -> Option<&str> {
        self.public_base.as_deref()
    }
}

impl Default for CssLinkOptions {
    fn default() -> Self {
        Self {
            file_name_template: AssetFileNameTemplate::new_unchecked(
                DEFAULT_CSS_FILE_NAME_TEMPLATE.to_string(),
            ),
            public_base: None,
            cache: Arc::new(Mutex::new(HashMap::new())),
        }
    }
}

impl PartialEq for CssLinkOptions {
    fn eq(&self, other: &Self) -> bool {
        self.file_name_template == other.file_name_template && self.public_base == other.public_base
    }
}

impl Eq for CssLinkOptions {}

fn validate_css_public_base(base: &str) -> Result<()> {
    if base.is_empty() {
        return Err(ParserError::Css(
            "css_public_base cannot be empty".to_string(),
        ));
    }
    if contains_invalid_href_byte(base) {
        return Err(ParserError::Css(
            "css_public_base cannot contain quotes, angle brackets, backslashes, or whitespace"
                .to_string(),
        ));
    }
    Ok(())
}

fn join_css_public_base(base: &str, css_filename: &str) -> String {
    let mut href = String::with_capacity(base.len() + css_filename.len() + 1);
    href.push_str(base);
    if !base.ends_with('/') {
        href.push('/');
    }
    href.push_str(css_filename);
    href
}

fn contains_invalid_href_byte(value: &str) -> bool {
    value
        .bytes()
        .any(|b| matches!(b, b'"' | b'\'' | b'<' | b'>' | b'\\') || b.is_ascii_whitespace())
}

#[cfg(test)]
#[allow(clippy::disallowed_methods)]
mod tests {
    use super::*;

    #[test]
    fn default_template_does_not_require_hash() {
        let options = CssLinkOptions::default();
        assert!(!options.file_name_template.uses_hash());
        let resolved = options.resolve("my-card", ".card { color: red; }");
        assert_eq!(resolved.filename, "my-card.css");
    }

    #[test]
    fn hash_template_uses_content_hash() {
        let options = CssLinkOptions::try_new("[name]-[hash].[ext]".to_string(), None).unwrap();
        assert!(options.file_name_template.uses_hash());
        let first = options.resolve("my-card", ".card { color: red; }");
        let second = options.resolve("other-card", ".card { color: blue; }");

        assert!(first.filename.starts_with("my-card-"));
        assert!(second.filename.starts_with("other-card-"));
        assert_ne!(
            first.filename.rsplit_once('-').map(|(_, hash)| hash),
            second.filename.rsplit_once('-').map(|(_, hash)| hash)
        );
    }

    #[test]
    fn filename_template_rejects_filesystem_unsafe_characters() {
        for template in [
            "[name]:[hash].[ext]",
            "[name]*[hash].[ext]",
            "[name]?[hash].[ext]",
            "[name]|[hash].[ext]",
            "résumé-[hash].[ext]",
        ] {
            let result = CssLinkOptions::try_new(template.to_string(), None);
            assert!(result.is_err(), "template should be rejected: {template}");
        }
    }
}