microformats 0.17.0

A union library of the Microformats types and associated parser.
Documentation 
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//! Metaformats head parsing module.
//!
//! This module handles parsing of HTML `<head>` elements for metaformats backcompat,
//! including Open Graph, Twitter Cards, and other meta tag vocabularies.

use microformats_types::{Class, Item, Properties, PropertyValue};
use url::Url;

/// Represents a meta tag with its attributes
#[derive(Debug, Clone)]
pub struct MetaTag {
    pub name: Option<String>,
    pub property: Option<String>,
    pub content: String,
}

/// Collect all meta tags from the head element
pub fn collect_meta_tags(head: &swc_html_ast::Element) -> Vec<MetaTag> {
    let mut meta_tags = Vec::new();

    fn traverse_element(element: &swc_html_ast::Element, meta_tags: &mut Vec<MetaTag>) {
        // Check if this element is a meta tag
        if element.tag_name.to_string() == "meta" {
            let name = element.attributes.iter()
                .find(|attr| attr.name.to_string() == "name")
                .and_then(|attr| attr.value.as_ref().map(|v| v.to_string()));

            let property = element.attributes.iter()
                .find(|attr| attr.name.to_string() == "property")
                .and_then(|attr| attr.value.as_ref().map(|v| v.to_string()));

            let content = element.attributes.iter()
                .find(|attr| attr.name.to_string() == "content")
                .and_then(|attr| attr.value.as_ref().map(|v| v.to_string()));

            if let Some(content) = content {
                meta_tags.push(MetaTag {
                    name,
                    property,
                    content,
                });
            }
        }

        // Recursively traverse children
        for child in &element.children {
            if let swc_html_ast::Child::Element(child_element) = child {
                traverse_element(child_element, meta_tags);
            }
        }
    }

    traverse_element(head, &mut meta_tags);
    meta_tags
}

/// Determine the item type based on meta tags and home page status
pub fn determine_item_type(meta_tags: &[MetaTag], is_home_page: bool) -> Vec<Class> {
    // Check for explicit og:type
    for tag in meta_tags {
        if let Some(property) = &tag.property {
            if property == "og:type" {
                match tag.content.as_str() {
                    "article" => {
                        if is_home_page {
                            return vec![Class::Known(microformats_types::KnownClass::Card)];
                        } else {
                            return vec![Class::Known(microformats_types::KnownClass::Entry)];
                        }
                    }
                    "profile" => return vec![Class::Known(microformats_types::KnownClass::Card)],
                    "music" | "video" => return vec![Class::Known(microformats_types::KnownClass::Cite)],
                    _ => {} // Continue checking other conditions
                }
            }
        }
    }

    // Check for Twitter card type
    for tag in meta_tags {
        if let Some(name) = &tag.name {
            if name == "twitter:card" {
                if matches!(tag.content.as_str(), "summary" | "summary_large_image") {
                    if is_home_page {
                        return vec![Class::Known(microformats_types::KnownClass::Card)];
                    } else {
                        return vec![Class::Known(microformats_types::KnownClass::Entry)];
                    }
                }
            }
        }
    }

    // Check for any og:* or twitter:* meta tags
    let has_og_tags = meta_tags.iter().any(|tag| tag.property.as_ref().map_or(false, |p| p.starts_with("og:")));
    let has_twitter_tags = meta_tags.iter().any(|tag| tag.name.as_ref().map_or(false, |n| n.starts_with("twitter:")));

    if has_og_tags || has_twitter_tags {
        if is_home_page {
            return vec![Class::Known(microformats_types::KnownClass::Card)];
        } else {
            return vec![Class::Known(microformats_types::KnownClass::Entry)];
        }
    }

    // Default fallback
    vec![Class::Known(microformats_types::KnownClass::Entry)]
}

/// Extract properties from meta tags
pub fn extract_properties(meta_tags: &[MetaTag], base_url: &Url, item_types: &[microformats_types::Class]) -> Properties {
    let mut properties = Properties::new();

    // Determine if this is an h-entry item (affects u-featured vs u-photo mapping)
    let is_entry = item_types.iter().any(|class| {
        matches!(class, microformats_types::Class::Known(microformats_types::KnownClass::Entry))
    });

    for tag in meta_tags {
        let content = &tag.content;
        if content.is_empty() {
            continue;
        }

        // Open Graph properties
        if let Some(property) = &tag.property {
            match property.as_str() {
                "og:title" => {
                    properties.insert("name".to_string(), vec![PropertyValue::Plain(content.clone())]);
                }
                "og:description" => {
                    properties.insert("summary".to_string(), vec![PropertyValue::Plain(content.clone())]);
                }
                "og:image" => {
                    if let Ok(url) = base_url.join(content) {
                        // For h-entry items, use u-featured instead of u-photo (Issue #5)
                        let property_name = if is_entry { "featured" } else { "photo" };
                        properties.insert(property_name.to_string(), vec![PropertyValue::Url(url)]);
                    }
                }
                "og:video" => {
                    if let Ok(url) = base_url.join(content) {
                        properties.insert("video".to_string(), vec![PropertyValue::Url(url)]);
                    }
                }
                "og:audio" => {
                    if let Ok(url) = base_url.join(content) {
                        properties.insert("audio".to_string(), vec![PropertyValue::Url(url)]);
                    }
                }
                "article:published_time" => {
                    // TODO: Parse as dt-published
                    properties.insert("published".to_string(), vec![PropertyValue::Plain(content.clone())]);
                }
                "article:modified_time" => {
                    // TODO: Parse as dt-updated
                    properties.insert("updated".to_string(), vec![PropertyValue::Plain(content.clone())]);
                }
                "article:author" => {
                    properties.insert("author".to_string(), vec![PropertyValue::Plain(content.clone())]);
                }
                _ => {}
            }
        }

        // Twitter properties (fallback to og:* if not present)
        if let Some(name) = &tag.name {
            match name.as_str() {
                "twitter:title" => {
                    if !properties.contains_key("name") {
                        properties.insert("name".to_string(), vec![PropertyValue::Plain(content.clone())]);
                    }
                }
                "twitter:description" => {
                    if !properties.contains_key("summary") {
                        properties.insert("summary".to_string(), vec![PropertyValue::Plain(content.clone())]);
                    }
                }
                "twitter:image" => {
                    if !properties.contains_key("photo") && !properties.contains_key("featured") {
                        if let Ok(url) = base_url.join(content) {
                            // For h-entry items, use u-featured instead of u-photo
                            let property_name = if is_entry { "featured" } else { "photo" };
                            properties.insert(property_name.to_string(), vec![PropertyValue::Url(url)]);
                        }
                    }
                }
                _ => {}
            }
        }
    }

    properties
}

/// Parse metaformats from head element
pub fn parse_metaformats_from_head(head: &swc_html_ast::Element, base_url: &Url, document_url: Option<&Url>) -> Option<Item> {
    let meta_tags = collect_meta_tags(head);

    // Determine if this is a home page
    let is_home_page = document_url.map_or(false, |url| {
        url.path() == "/" || url.path() == "/index.html"
    });

    let types = determine_item_type(&meta_tags, is_home_page);
    let mut properties = extract_properties(&meta_tags, base_url, &types);

    // Apply fallbacks for missing properties (Issue #1)
    if !types.is_empty() {
        apply_fallback_properties(head, &mut properties);
    }

    // If we have no representative images from meta tags, try icon fallback (Issue #6)
    if !properties.contains_key("photo") && !properties.contains_key("featured") {
        if let Some(icon_url) = find_icon_url(head, base_url) {
            // Use u-photo for icons (they're representative images)
            properties.insert("photo".to_string(), vec![PropertyValue::Url(icon_url)]);
        }
    }

    if types.is_empty() && properties.is_empty() {
        None
    } else {
        let mut item = Item::new(types);
        item.properties = properties;
        Some(item)
    }
}

/// Apply fallback properties when no meta tags are present (Issue #1)
fn apply_fallback_properties(head: &swc_html_ast::Element, properties: &mut Properties) {
    // Find title element
    if !properties.contains_key("name") {
        if let Some(title_content) = find_title_content(head) {
            properties.insert("name".to_string(), vec![PropertyValue::Plain(title_content)]);
        }
    }

    // Find meta description
    if !properties.contains_key("summary") {
        if let Some(description_content) = find_meta_description_content(head) {
            properties.insert("summary".to_string(), vec![PropertyValue::Plain(description_content)]);
        }
    }
}

/// Find title content from document head
fn find_title_content(head: &swc_html_ast::Element) -> Option<String> {
    fn find_title_recursive(element: &swc_html_ast::Element) -> Option<String> {
        if element.tag_name.to_string() == "title" {
            // Extract text content from title element
            let mut text = String::new();
            for child in &element.children {
                if let swc_html_ast::Child::Text(text_node) = child {
                    text.push_str(&text_node.data);
                }
            }
            return Some(text.trim().to_string());
        }

        for child in &element.children {
            if let swc_html_ast::Child::Element(child_element) = child {
                if let Some(title) = find_title_recursive(child_element) {
                    return Some(title);
                }
            }
        }
        None
    }

    find_title_recursive(head)
}

/// Find meta description content from document head
fn find_meta_description_content(head: &swc_html_ast::Element) -> Option<String> {
    fn find_meta_recursive(element: &swc_html_ast::Element) -> Option<String> {
        if element.tag_name.to_string() == "meta" {
            let mut is_description = false;
            let mut content = None;

            for attr in &element.attributes {
                match attr.name.to_string().as_str() {
                    "name" => {
                        if let Some(value) = &attr.value {
                            if value.to_string() == "description" {
                                is_description = true;
                            }
                        }
                    }
                    "content" => {
                        if let Some(value) = &attr.value {
                            content = Some(value.to_string());
                        }
                    }
                    _ => {}
                }
            }

            if is_description {
                return content;
            }
        }

        for child in &element.children {
            if let swc_html_ast::Child::Element(child_element) = child {
                if let Some(description) = find_meta_recursive(child_element) {
                    return Some(description);
                }
            }
        }
        None
    }

    find_meta_recursive(head)
}

/// Find icon URL from document head (Issue #6)
fn find_icon_url(head: &swc_html_ast::Element, base_url: &Url) -> Option<Url> {
    fn find_link_recursive(element: &swc_html_ast::Element, base_url: &Url) -> Option<Url> {
        if element.tag_name.to_string() == "link" {
            let mut is_icon = false;
            let mut href = None;

            for attr in &element.attributes {
                match attr.name.to_string().as_str() {
                    "rel" => {
                        if let Some(value) = &attr.value {
                            let rel_value = value.to_string();
                            // Check for various icon types (Issue #6)
                            if rel_value == "icon" ||
                               rel_value == "apple-touch-icon" ||
                               rel_value == "msapplication-TileImage" {
                                is_icon = true;
                            }
                        }
                    }
                    "href" => {
                        if let Some(value) = &attr.value {
                            href = Some(value.to_string());
                        }
                    }
                    _ => {}
                }
            }

            if is_icon {
                if let Some(href) = href {
                    return base_url.join(&href).ok();
                }
            }
        }

        for child in &element.children {
            if let swc_html_ast::Child::Element(child_element) = child {
                if let Some(icon_url) = find_link_recursive(child_element, base_url) {
                    return Some(icon_url);
                }
            }
        }
        None
    }

    find_link_recursive(head, base_url)
}

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

    #[test]
    fn test_determine_item_type_home_page() {
        let meta_tags = vec![
            MetaTag {
                name: None,
                property: Some("og:type".to_string()),
                content: "article".to_string(),
            }
        ];

        let types = determine_item_type(&meta_tags, true);
        assert_eq!(types.len(), 1);
        // Should be h-card for home page
        match &types[0] {
            Class::Known(known) => assert_eq!(known.to_string(), "h-card"),
            _ => panic!("Expected known class"),
        }
    }

    #[test]
    fn test_determine_item_type_regular_page() {
        let meta_tags = vec![
            MetaTag {
                name: None,
                property: Some("og:type".to_string()),
                content: "article".to_string(),
            }
        ];

        let types = determine_item_type(&meta_tags, false);
        assert_eq!(types.len(), 1);
        // Should be h-entry for regular page
        match &types[0] {
            Class::Known(known) => assert_eq!(known.to_string(), "h-entry"),
            _ => panic!("Expected known class"),
        }
    }

    #[cfg(all(test, feature = "metaformats"))]
    #[test]
    fn test_metaformats_basic_og_tags() -> Result<(), crate::Error> {
        use crate::parse::Parser;

        let html = r#"
        <!DOCTYPE html>
        <html>
        <head>
            <meta property="og:title" content="Test Title">
            <meta property="og:description" content="Test Description">
            <meta property="og:type" content="article">
        </head>
        <body></body>
        </html>
        "#;

        let doc = Parser::from_html(html.to_string())?.into_document(Some("https://example.com".parse()?))?;

        assert!(doc.meta_item.is_some());
        let meta_item = doc.meta_item.as_ref().unwrap();
        assert_eq!(meta_item.r#type.len(), 1);
        assert_eq!(meta_item.r#type[0].to_string(), "h-entry");

        let name_values = meta_item.properties.get("name").unwrap();
        assert_eq!(name_values.len(), 1);
        assert_eq!(name_values[0], PropertyValue::Plain("Test Title".to_string()));

        let summary_values = meta_item.properties.get("summary").unwrap();
        assert_eq!(summary_values.len(), 1);
        assert_eq!(summary_values[0], PropertyValue::Plain("Test Description".to_string()));

        Ok(())
    }

    #[cfg(all(test, feature = "metaformats"))]
    #[test]
    fn test_metaformats_u_featured_for_entry() -> Result<(), crate::Error> {
        use crate::parse::Parser;

        let html = r#"
        <!DOCTYPE html>
        <html>
        <head>
            <meta property="og:title" content="Test Title">
            <meta property="og:image" content="https://example.com/image.jpg">
            <meta property="og:type" content="article">
        </head>
        <body></body>
        </html>
        "#;

        let doc = Parser::from_html(html.to_string())?.into_document(Some("https://example.com".parse()?))?;

        assert!(doc.meta_item.is_some());
        let meta_item = doc.meta_item.as_ref().unwrap();

        // Should use u-featured for h-entry items
        let featured_values = meta_item.properties.get("featured").unwrap();
        assert_eq!(featured_values.len(), 1);
        assert!(matches!(featured_values[0], PropertyValue::Url(_)));

        // Should not have u-photo
        assert!(meta_item.properties.get("photo").is_none());

        Ok(())
    }

    #[cfg(all(test, feature = "metaformats"))]
    #[test]
    fn test_metaformats_title_fallback() -> Result<(), crate::Error> {
        use crate::parse::Parser;

        let html = r#"
        <!DOCTYPE html>
        <html>
        <head>
            <title>Fallback Title</title>
            <meta name="twitter:card" content="summary">
        </head>
        <body></body>
        </html>
        "#;

        let doc = Parser::from_html(html.to_string())?.into_document(Some("https://example.com".parse()?))?;

        assert!(doc.meta_item.is_some());
        let meta_item = doc.meta_item.as_ref().unwrap();

        // Should use title as fallback for p-name
        let name_values = meta_item.properties.get("name").unwrap();
        assert_eq!(name_values.len(), 1);
        assert_eq!(name_values[0], PropertyValue::Plain("Fallback Title".to_string()));

        Ok(())
    }

    #[cfg(all(test, feature = "metaformats"))]
    #[test]
    fn test_metaformats_icon_fallback() -> Result<(), crate::Error> {
        use crate::parse::Parser;

        let html = r#"
        <!DOCTYPE html>
        <html>
        <head>
            <title>Site Title</title>
            <link rel="icon" href="/favicon.ico">
            <meta name="twitter:card" content="summary">
        </head>
        <body></body>
        </html>
        "#;

        let doc = Parser::from_html(html.to_string())?.into_document(Some("https://example.com".parse()?))?;

        assert!(doc.meta_item.is_some());
        let meta_item = doc.meta_item.as_ref().unwrap();

        // Should use icon as fallback for u-photo
        let photo_values = meta_item.properties.get("photo").unwrap();
        assert_eq!(photo_values.len(), 1);
        assert!(matches!(photo_values[0], PropertyValue::Url(_)));

        Ok(())
    }
}