use lazy_static::lazy_static;
use lol_html::html_content::Element;
use lol_html::{element, text, HtmlRewriter, Selector, Settings};
use regex::Regex;
use std::cell::RefCell;
use std::collections::BTreeMap;
use std::default::Default;
use std::rc::Rc;

use crate::SearchOptions;

use super::normalize_content;

lazy_static! {
    static ref ALL_SPACES: Regex = Regex::new("\\s").unwrap();
    static ref SENTENCE_CHARS: Regex = Regex::new("[\\w'\"\\)\\$\\*]").unwrap();
}
lazy_static! {
    static ref ATTRIBUTE_MATCH: Regex =
        Regex::new("^\\s*(?P<name>[^:\\[\\]]+)\\[(?P<attribute>.+)\\]\\s*$").unwrap();
}

const SENTENCE_SELECTORS: &[&'static str] = &[
    "h1", "h2", "h3", "h4", "h5", "h6", "p", "td", "div", "ul", "li", "dl", "dt", "dd", "article",
    "section",
];
const INLINE_SELECTORS: &[&'static str] = &[
    "a", "abbr", "acronym", "b", "bdo", "big", "br", "button", "cite", "code", "dfn", "em", "i",
    "img", "input", "kbd", "label", "map", "object", "output", "q", "samp", "script", "select",
    "small", "span", "strong", "sub", "sup", "textarea", "time", "tt", "var",
];
const REMOVE_SELECTORS: &[&'static str] = &[
    "head", "style", "script", "noscript", "label", "form", "svg", "footer", "nav", "iframe",
    "template",
];
const SPACE_SELECTORS: &[&'static str] = &["br"];

// We aren't transforming HTML, just parsing, so we dump the output.
#[derive(Default)]
struct EmptySink;
impl lol_html::OutputSink for EmptySink {
    fn handle_chunk(&mut self, _: &[u8]) {}
}

/// Houses the HTML parsing instance and the internal data while parsing
pub struct DomParser<'a> {
    rewriter: HtmlRewriter<'a, EmptySink>,
    data: Rc<RefCell<DomParserData>>,
}

// The internal state while parsing,
// with a reference to the deepest HTML element
// that we're currently reading
#[derive(Default, Debug)]
struct DomParserData {
    current_node: Rc<RefCell<DomParsingNode>>,
    filters: BTreeMap<String, Vec<String>>,
    sort: BTreeMap<String, String>,
    meta: BTreeMap<String, String>,
    default_meta: BTreeMap<String, String>,
    anchor_content: BTreeMap<String, String>,
    anchor_titles: BTreeMap<String, String>,
    language: Option<String>,
    has_html_element: bool,
    has_old_bundle_reference: bool,
    has_default_ui_reference: bool,
}

#[derive(Clone, Copy, Debug, PartialEq)]
enum NodeStatus {
    Indexing,
    // Our content & children should not be indexed
    Ignored,
    // Our content & children should be excluded entirely
    // (including meta / filters)
    Excluded,
    Body,
    // There was a body element below us,
    // so our content should be ignored.
    ParentOfBody,
}

impl Default for NodeStatus {
    fn default() -> Self {
        Self::Indexing
    }
}

// A single HTML element that we're reading into.
// Contains a reference to the parent element,
// and since we collapse this tree upwards while we parse,
// we don't need to store tree structure.
#[derive(Default, Debug)]
struct DomParsingNode {
    current_value: String,
    parent: Option<Rc<RefCell<DomParsingNode>>>,
    filter: Option<Vec<String>>,
    sort: Option<Vec<String>>,
    meta: Option<Vec<String>>,
    default_meta: Option<Vec<String>>,
    weight: Option<String>,
    anchor_ids: Option<Vec<String>>,
    status: NodeStatus,
}

/// The search-relevant data that was retrieved from the given input
#[derive(Debug)]
pub struct DomParserResult {
    pub digest: String,
    pub filters: BTreeMap<String, Vec<String>>,
    pub sort: BTreeMap<String, String>,
    pub meta: BTreeMap<String, String>,
    pub anchor_content: BTreeMap<String, String>,
    pub anchor_titles: BTreeMap<String, String>,
    pub has_custom_body: bool,
    pub force_inclusion: bool, // Include this page even if there is no body
    pub has_html_element: bool,
    pub has_old_bundle_reference: bool,
    pub has_default_ui_reference: bool,
    pub language: String,
}

// Some shorthand to clean up our use of Rc<RefCell<*>> in the lol_html macros
// From https://github.com/rust-lang/rfcs/issues/2407#issuecomment-385291238
macro_rules! enclose {
    ( ($( $x:ident ),*) $y:expr ) => {
        {
            $(let $x = $x.clone();)*
            $y
        }
    };
}

impl<'a> DomParser<'a> {
    pub fn new(options: &'a SearchOptions) -> Self {
        let data = Rc::new(RefCell::new(DomParserData::default()));
        let root = format!("{}, {} *", options.root_selector, options.root_selector);
        let mut custom_exclusions = options.exclude_selectors.clone();
        custom_exclusions.extend(REMOVE_SELECTORS.iter().map(|s| s.to_string()));
        let custom_exclusions = custom_exclusions
            .iter()
            .filter_map(|e| {
                let selector = format!("{} {}", options.root_selector, e);
                match selector.parse::<Selector>() {
                    Ok(_) => Some(selector),
                    Err(error) => {
                        options.logger.warn(format!(
                            "Ignoring the exclude selector {e:?}, which Pagefind can't parse: {error}. Indexing will continue without it."
                        ));
                        None
                    }
                }
            })
            .collect::<Vec<_>>()
            .join(", ");
        let mut anchor_counter = 0;

        let rewriter = HtmlRewriter::new(
            vec![
                    enclose! { (data) element!("html", move |el| {
                        let mut data = data.borrow_mut();
                        data.has_html_element = true;
                        if let Some(lang) = el.get_attribute("lang") {
                            data.language = Some(lang.to_lowercase());
                        }
                        Ok(())
                    })},
                    enclose! { (data) element!(root, move |el| {
                        let explicit_ignore_flag = el.get_attribute("data-pagefind-ignore").map(|attr| {
                            match attr.to_ascii_lowercase().as_str() {
                                "" | "index" | "true" => NodeStatus::Ignored,
                                "all" => NodeStatus::Excluded,
                                _ => {
                                    options.logger.warn(format!("data-pagefind-ignore value of \"{}\" is not valid. Expected no value, or one of: [index, all]. Assuming 'all' and excluding this element entirely.", attr));
                                    NodeStatus::Excluded
                                }
                            }
                        });
                        let treat_as_body = el.has_attribute("data-pagefind-body");
                        let weight = el.get_attribute("data-pagefind-weight").map(|attr| attr.to_string());
                        let filter = el.get_attribute("data-pagefind-filter").map(|attr| parse_attr_string(attr, el));
                        let element_id = el.get_attribute("id").map(|e| ALL_SPACES.replace_all(&e, "").to_string());
                        let pagefind_title = el.get_attribute("data-pagefind-title").map(|title| normalize_content(&title)).filter(|title| !title.is_empty());
                        let meta = el.get_attribute("data-pagefind-meta").map(|attr| parse_attr_string(attr, el));
                        let default_meta = el.get_attribute("data-pagefind-default-meta").map(|attr| parse_attr_string(attr, el));
                        let sort = el.get_attribute("data-pagefind-sort").map(|attr| parse_attr_string(attr, el));
                        let index_attrs: Option<Vec<String>> = el.get_attribute("data-pagefind-index-attrs").map(|attr| attr.split(',').map(|a| a.trim().to_string()).collect());
                        let tag_name = el.tag_name();

                        let status = if treat_as_body {
                            NodeStatus::Body
                        } else if let Some(explicit_ignore_flag) = explicit_ignore_flag {
                            explicit_ignore_flag
                        } else {
                            NodeStatus::Indexing
                        };

                        let mut anchor_id = None;
                        if status != NodeStatus::Excluded && status != NodeStatus::Ignored {
                            if let Some(element_id) = element_id {
                                let parent = &data.borrow().current_node;
                                let mut parent = parent.borrow_mut();
                                // Don't insert anchors if this node is outside of a body-tree
                                if !(parent.status == NodeStatus::ParentOfBody
                                    && status != NodeStatus::Body
                                    && status != NodeStatus::ParentOfBody) {
                                    parent.current_value.push_str(&format!(" ___PAGEFIND_ANCHOR___{tag_name}:{anchor_counter}:{element_id} "));
                                    anchor_id = Some(format!("{anchor_counter}:{element_id}"));
                                    anchor_counter += 1;
                                }
                            }
                        }

                        if let (Some(anchor_id), Some(title)) = (&anchor_id, pagefind_title) {
                            data.borrow_mut().anchor_titles.insert(anchor_id.clone(), title);
                        }

                        if status != NodeStatus::Excluded {
                            if let Some(attrs) = index_attrs {
                                let parent = &data.borrow().current_node;
                                for attr in attrs {
                                    let mut value = el.get_attribute(attr.trim()).unwrap_or_default();
                                    if value.chars()
                                        .last()
                                        .filter(|c| SENTENCE_CHARS.is_match(&c.to_string()))
                                        .is_some() {
                                            value.push('.');
                                        }
                                    let mut parent = parent.borrow_mut();
                                    parent.current_value.push(' ');
                                    parent.current_value.push_str(&value);
                                    parent.current_value.push(' ');
                                }
                            }
                            // Handle adding spaces between words separated by <br/> tags and the like
                            if SPACE_SELECTORS.contains(&el.tag_name().as_str()) {
                                let parent = &data.borrow().current_node;
                                let mut parent = parent.borrow_mut();
                                parent.current_value.push(' ');
                            }
                        }

                        let node = {
                            let mut data = data.borrow_mut();
                            let parent_node = data.current_node.borrow();
                            let parent_status = parent_node.status;

                            let mut node_anchors = if parent_node.anchor_ids.is_some() && INLINE_SELECTORS.contains(&tag_name.as_str()) {
                                parent_node.anchor_ids.clone()
                            } else {
                                None
                            };

                            if let Some(this_node_anchor_id) = anchor_id {
                                if let Some(existing) = node_anchors.as_mut() {
                                    existing.push(this_node_anchor_id);
                                } else {
                                    node_anchors = Some(vec![this_node_anchor_id]);
                                }
                            }

                            let node = Rc::new(RefCell::new(DomParsingNode{
                                parent: Some(Rc::clone(&data.current_node)),
                                status: match parent_status {
                                    NodeStatus::Excluded => parent_status,
                                    _ => status,
                                },
                                filter,
                                meta,
                                default_meta,
                                sort,
                                anchor_ids: node_anchors,
                                current_value: String::default(),
                                weight,
                            }));

                            drop(parent_node);
                            data.current_node = Rc::clone(&node);
                            node
                        };

                        let can_have_content = if let Some(handlers) = el.end_tag_handlers() {
                            handlers.push(Box::new(enclose! { (data, node, tag_name) move |end| {
                            let mut data = data.borrow_mut();
                            let mut node = node.borrow_mut();

                            // When we reach an end tag, we need to
                            // make sure to move focus back to the parent node.
                            if let Some(parent) = &node.parent {
                                data.current_node = Rc::clone(parent);
                            }

                            // For fully-excluded elements, we want to bail before we
                            // even get to filters or metadata.
                            if node.status == NodeStatus::Excluded {
                                return Ok(());
                            }

                            // Process filters & meta before we continue
                            // (Filters & meta are valid on ignored elements)
                            if let Some(filters) = &node.filter {
                                for filter in filters {
                                    if let Some((filter, value)) = node.get_attribute_pair(filter) {
                                        match data.filters.get_mut(&filter) {
                                            Some(filter_arr) => filter_arr.push(normalize_content(&value)),
                                            None => {
                                                data.filters.insert(filter, vec![
                                                    normalize_content(&value)
                                                ]);
                                            }
                                        }
                                    }
                                }
                            }

                            if let Some(sorts) = &node.sort {
                                for sort in sorts {
                                    if let Some((sort, value)) = node.get_attribute_pair(sort) {
                                        data.sort.insert(sort, value);
                                    }
                                }
                            }

                            if let Some(metas) = &node.meta {
                                for meta in metas {
                                    if let Some((meta, value)) = node.get_attribute_pair(meta) {
                                        data.meta.insert(meta, value);
                                    }
                                }
                            }
                            if let Some(metas) = &node.default_meta {
                                for meta in metas {
                                    if let Some((meta, value)) = node.get_attribute_pair(meta) {
                                        data.default_meta.insert(meta, value);
                                    }
                                }
                            }

                            // Try to capture the first title on the page (if unset)
                            if tag_name == "h1" && !data.meta.contains_key("auto_title") && !node.current_value.trim().is_empty() {
                                data.meta.insert("auto_title".into(), normalize_content(&node.current_value));
                            }
                            // Try to capture the actual title of the page as a fallback for later
                            if tag_name == "title" && !data.meta.contains_key("auto_page_title") {
                                data.meta.insert("auto_page_title".into(), normalize_content(&node.current_value));
                            }

                            // If we bail out now, the content won't be persisted anywhere
                            // and the node + children will be dropped.
                            if node.status == NodeStatus::Ignored {
                                return Ok(());
                            }

                            let tag_name = end.name();
                            if SENTENCE_SELECTORS.contains(&tag_name.as_str()) {
                                // For block elements, we want to make sure sentences
                                // don't hug each other without whitespace.
                                // We normalize repeated whitespace later, so we
                                // can add this indiscriminately.
                                node.current_value.insert(0, ' ');

                                // Similarly, we want to separate block elements
                                // with punctuation, so that the excerpts read nicely.
                                // (As long as it doesn't already end with, say, a . or ?)
                                // Description list terms lead into their details,
                                // so they get a colon instead.
                                if node.current_value.chars()
                                    .last()
                                    .filter(|c| SENTENCE_CHARS.is_match(&c.to_string()))
                                    .is_some() {
                                        node.current_value.push(if tag_name == "dt" { ':' } else { '.' });
                                }
                                node.current_value.push(' ');
                            }

                            if let Some(weight) = &node.weight {
                                node.current_value = [
                                    " ___PAGEFIND_WEIGHT___",
                                    &weight,
                                    " ",
                                    &node.current_value,
                                    " ___END_PAGEFIND_WEIGHT___ "
                                ].concat();
                            } else {
                                if let Some(auto_weight) = match &tag_name[..] {
                                    "h1" => Some("7".to_string()),
                                    "h2" => Some("6".to_string()),
                                    "h3" => Some("5".to_string()),
                                    "h4" => Some("4".to_string()),
                                    "h5" => Some("3".to_string()),
                                    "h6" => Some("2".to_string()),
                                    _ => None,
                                } {
                                    node.current_value = [
                                        " ___PAGEFIND_AUTO_WEIGHT___",
                                        &auto_weight,
                                        " ",
                                        &node.current_value,
                                        " ___END_PAGEFIND_WEIGHT___ "
                                    ].concat();
                                }
                            }

                            // Huck all of the content we have onto the end of the
                            // content that the parent node has (so far)
                            // This will include all of our children's content,
                            // and the order of tree traversal will mean that it
                            // is inserted in the correct position in the parent's content.
                            let mut parent = data.current_node.borrow_mut();

                            // If the parent is a parent of a body, we don't want to append
                            // any more content to it. (Unless, of course, we are representing another body)
                            if parent.status == NodeStatus::ParentOfBody
                                && node.status != NodeStatus::Body
                                && node.status != NodeStatus::ParentOfBody {
                                    return Ok(());
                            }
                            match node.status {
                                NodeStatus::Ignored | NodeStatus::Excluded => {},
                                NodeStatus::Indexing => {
                                    parent.current_value.push_str(&node.current_value);
                                },
                                NodeStatus::Body | NodeStatus::ParentOfBody => {
                                    // If our parent is already a parent of a body, then
                                    // we're probably a subsequent body. Avoid clearing it out.
                                    if parent.status != NodeStatus::ParentOfBody {
                                        parent.current_value.clear();
                                    }
                                    parent.current_value.push_str(&node.current_value);
                                    parent.status = NodeStatus::ParentOfBody;
                                }
                            };

                            Ok(())
                        }}));
                            true
                        } else {
                            false
                        };

                        // Try to handle tags like <img /> which have no end tag,
                        // and thus will never hit the logic to reset the current node.
                        // TODO: This could still be missed for tags with implied ends?
                        if !can_have_content {
                            let mut data = data.borrow_mut();
                            let node = node.borrow();
                            if let Some(parent) = &node.parent {
                                data.current_node = Rc::clone(parent);
                            }

                            // For fully-excluded elements, we want to bail before we
                            // even get to filters or metadata.
                            if node.status == NodeStatus::Excluded {
                                return Ok(());
                            }

                            // Process filters & meta before we continue
                            // TODO: Abstract repetition into function
                            if let Some(filters) = &node.filter {
                                for filter in filters {
                                    if let Some((filter, value)) = node.get_attribute_pair(filter) {
                                        match data.filters.get_mut(&filter) {
                                            Some(filter_arr) => filter_arr.push(normalize_content(&value)),
                                            None => {
                                                data.filters.insert(filter, vec![
                                                    normalize_content(&value)
                                                ]);
                                            }
                                        }
                                    }
                                }
                            }

                            if let Some(sorts) = &node.sort {
                                for sort in sorts {
                                    if let Some((sort, value)) = node.get_attribute_pair(sort) {
                                        data.sort.insert(sort, value);
                                    }
                                }
                            }

                            if let Some(metas) = &node.meta {
                                for meta in metas {
                                    if let Some((meta, value)) = node.get_attribute_pair(meta) {
                                        data.meta.insert(meta, value);
                                    }
                                }
                            }
                            if let Some(metas) = &node.default_meta {
                                for meta in metas {
                                    if let Some((meta, value)) = node.get_attribute_pair(meta) {
                                        data.default_meta.insert(meta, value);
                                    }
                                }
                            }

                            // Try to capture the first image _after_ a title (if unset)
                            if tag_name == "img"
                                && !data.meta.contains_key("auto_image")
                                && (data.meta.contains_key("auto_title") || data.meta.contains_key("title")) {
                                if let Some(src) = el.get_attribute("src") {
                                    data.meta.insert("auto_image".into(), src);

                                    if let Some(alt) = el.get_attribute("alt") {
                                        data.meta.insert("auto_image_alt".into(), alt);
                                    }
                                }
                            }
                        }
                        Ok(())
                    })},
                    // If we hit a selector that should be excluded, mark whatever the current node is as such
                    enclose! { (data) element!(custom_exclusions, move |_el| {
                        let data = data.borrow_mut();
                        let mut node = data.current_node.borrow_mut();
                        node.status = NodeStatus::Ignored;
                        Ok(())
                    })},
                    // Slap any text we encounter inside the body into the current node's current value
                    enclose! { (data) text!(&options.root_selector, move |el| {
                        let mut data = data.borrow_mut();
                        let mut node = data.current_node.borrow_mut();
                        let element_text = el.as_str();
                        node.current_value.push_str(element_text);

                        let node_is_ignored = node.status == NodeStatus::Ignored || node.status == NodeStatus::Excluded;

                        if !node_is_ignored && node.anchor_ids.is_some() {
                            let anchor_ids = node.anchor_ids.clone().unwrap();
                            drop(node);
                            for anchor_id in anchor_ids {
                                if let Some(anchor_text) = data.anchor_content.get_mut(&anchor_id) {
                                    anchor_text.push_str(element_text);
                                } else {
                                    data.anchor_content.insert(anchor_id, element_text.to_string());
                                }
                            }
                        }
                        Ok(())
                    })},
                    // Dig into script and style references to see if they refer to pre-1.0 conventions
                    // or the Default UI (pagefind-ui.js / pagefind-modular-ui.js)
                    enclose! { (data) element!("script, link", move |el| {
                        if el.tag_name() == "script" {
                            if let Some(src) = el.get_attribute("src") {
                                if src.starts_with("_pagefind") || src.contains("/_pagefind") {
                                    let mut data = data.borrow_mut();
                                    data.has_old_bundle_reference = true;
                                }
                                if src.contains("pagefind-ui.js") || src.contains("pagefind-modular-ui.js") {
                                    let mut data = data.borrow_mut();
                                    data.has_default_ui_reference = true;
                                }
                            }
                        } else if el.tag_name() == "link" {
                            if let Some(href) = el.get_attribute("href") {
                                if href.starts_with("_pagefind") || href.contains("/_pagefind") {
                                    let mut data = data.borrow_mut();
                                    data.has_old_bundle_reference = true;
                                }
                                if href.contains("pagefind-ui.css") || href.contains("pagefind-modular-ui.css") {
                                    let mut data = data.borrow_mut();
                                    data.has_default_ui_reference = true;
                                }
                            }
                        }
                        Ok(())
                    })},
            ]
            .into_iter()
            .fold(Settings::new().with_strict(false), |settings, handler| {
                settings.append_element_content_handler(handler)
            }),
            EmptySink::default(),
        );

        Self { rewriter, data }
    }

    /// Writes a chunk of data to the underlying HTML parser
    pub fn write(&mut self, data: &[u8]) -> Result<(), lol_html::errors::RewritingError> {
        self.rewriter.write(data)
    }

    /// Performs any post-processing and returns the summated search results
    pub fn wrap(self) -> DomParserResult {
        drop(self.rewriter); // Clears the extra Rcs on and within data
        let mut data = Rc::try_unwrap(self.data).unwrap().into_inner();
        let mut node = data.current_node;

        // Fallback: If we are left with a tree, collapse it up into the parents
        // until we get to the root node.
        while node.borrow().parent.is_some() {
            {
                let node = node.borrow();
                let mut parent = node.parent.as_ref().unwrap().borrow_mut();
                if parent.status != NodeStatus::ParentOfBody {
                    match node.status {
                        NodeStatus::Ignored | NodeStatus::Excluded => {}
                        NodeStatus::Indexing => {
                            parent.current_value.push_str(&node.current_value);
                        }
                        NodeStatus::Body | NodeStatus::ParentOfBody => {
                            parent.current_value.clear();
                            parent.current_value.push_str(&node.current_value);
                            parent.status = NodeStatus::ParentOfBody;
                        }
                    };
                }
            }
            let old_node = node.borrow();
            let new_node = Rc::clone(old_node.parent.as_ref().unwrap());
            drop(old_node);
            node = new_node;
        }

        if let Some(image) = data.meta.remove("auto_image") {
            let alt = data.meta.remove("auto_image_alt").unwrap_or_default();
            if !data.meta.contains_key("image") {
                data.meta.insert("image".into(), image);
                data.meta.insert("image_alt".into(), alt);
            }
        }

        if let Some(title) = data.meta.remove("auto_title") {
            if !data.meta.contains_key("title") {
                data.meta.insert("title".into(), title);
            }
        }
        if let Some(title) = data.meta.remove("auto_page_title") {
            if !data.meta.contains_key("title") {
                data.meta.insert("title".into(), title);
            }
        }

        // Merge the collected metadata over top of the defaults, if any
        data.default_meta.extend(data.meta);

        let node = node.borrow();

        DomParserResult {
            digest: normalize_content(&node.current_value),
            filters: data.filters,
            sort: data.sort,
            meta: data.default_meta,
            anchor_content: data.anchor_content,
            anchor_titles: data.anchor_titles,
            has_custom_body: node.status == NodeStatus::ParentOfBody,
            force_inclusion: false,
            has_html_element: data.has_html_element,
            has_old_bundle_reference: data.has_old_bundle_reference,
            has_default_ui_reference: data.has_default_ui_reference,
            language: data
                .language
                .filter(|lang| !lang.is_empty())
                .unwrap_or_else(|| "unknown".into()),
        }
    }
}

fn parse_attr_string(input: String, el: &Element) -> Vec<String> {
    if let Some((attrs, literal)) = input.split_once(':') {
        let mut attrs = parse_attr_string(attrs.to_owned(), el);
        if let Some(last) = attrs.last_mut() {
            last.push(':');
            last.push_str(literal);
        }
        return attrs;
    }
    input
        .split(',')
        .map(|chunk| {
            let chunk = chunk.trim();
            if let Some(value) = ATTRIBUTE_MATCH.captures(chunk) {
                let name = value.name("name").unwrap().as_str().to_owned();
                let attr = value.name("attribute").unwrap().as_str().to_owned();
                format!("{}:{}", name, el.get_attribute(&attr).unwrap_or_default())
            } else {
                chunk.to_owned()
            }
        })
        .collect()
}

impl DomParsingNode {
    fn get_attribute_pair(&self, input: &str) -> Option<(String, String)> {
        match input.split_once(':') {
            Some((filter, value)) => Some((filter.to_owned(), normalize_content(&value))),
            None => {
                if self.current_value.is_empty() {
                    None
                } else {
                    Some((input.to_owned(), normalize_content(&self.current_value)))
                }
            }
        }
    }
}

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

    #[test]
    fn get_filter_from_node() {
        let mut node = DomParsingNode::default();

        assert_eq!(node.get_attribute_pair("color"), None);

        node.current_value = "White".into();
        assert_eq!(
            node.get_attribute_pair("color"),
            Some(("color".into(), "White".into()))
        );

        assert_eq!(
            node.get_attribute_pair("color:auburn"),
            Some(("color".into(), "auburn".into()))
        );

        assert_eq!(
            node.get_attribute_pair("color:ye:llow"),
            Some(("color".into(), "ye:llow".into()))
        );
    }

    fn test_raw_parse(input: Vec<&'static str>) -> DomParserResult {
        use clap::CommandFactory;
        let config_args = vec![twelf::Layer::Clap(
            crate::PagefindInboundConfig::command().get_matches_from(vec![
                "pagefind",
                "--source",
                "not_important",
            ]),
        )];
        let config =
            SearchOptions::load(crate::PagefindInboundConfig::with_layers(&config_args).unwrap())
                .unwrap();
        let mut rewriter = DomParser::new(&config);
        for line in input {
            let _ = rewriter.write(line.as_bytes());
        }
        rewriter.wrap()
    }

    fn test_parse(mut input: Vec<&'static str>) -> DomParserResult {
        input.insert(0, "<html><body>");
        input.push("</body></html>");
        test_raw_parse(input)
    }

    fn test_parse_with_exclusions(
        mut input: Vec<&'static str>,
        exclusions: &[&'static str],
    ) -> DomParserResult {
        use clap::CommandFactory;
        let mut args = vec!["pagefind", "--source", "not_important"];
        for exclusion in exclusions {
            args.push("--exclude-selectors");
            args.push(exclusion);
        }
        let config_args = vec![twelf::Layer::Clap(
            crate::PagefindInboundConfig::command().get_matches_from(args),
        )];
        let config =
            SearchOptions::load(crate::PagefindInboundConfig::with_layers(&config_args).unwrap())
                .unwrap();
        let mut rewriter = DomParser::new(&config);
        input.insert(0, "<html><body>");
        input.push("</body></html>");
        for line in input {
            let _ = rewriter.write(line.as_bytes());
        }
        rewriter.wrap()
    }

    #[test]
    fn unsupported_exclude_selector_does_not_halt_indexing() {
        let data = test_parse_with_exclusions(
            vec!["<p>Kept</p>", "<div class='ad'>Dropped</div>"],
            &[":not(.a b)", ".ad"],
        );

        assert_eq!(data.digest, "Kept.");
    }

    #[test]
    fn words_weights() {
        let data = test_parse(vec![
            "<p>Weight one</p>",
            "<p data-pagefind-weight='2'>Weight two</p>",
        ]);

        assert_eq!(
            data.digest,
            "Weight one. ___PAGEFIND_WEIGHT___2 Weight two. ___END_PAGEFIND_WEIGHT___"
        )
    }

    #[test]
    fn words_ids() {
        let data = test_parse(vec![
            "<p>Sentence one</p>",
            "<br id='break' />",
            "<p id='pid'>Sentence two</p>",
        ]);

        assert_eq!(
            data.digest,
            "Sentence one. ___PAGEFIND_ANCHOR___br:0:break ___PAGEFIND_ANCHOR___p:1:pid Sentence two."
        )
    }

    #[test]
    fn explicit_anchor_titles() {
        let data = test_parse(vec![
            "<section id='usage' data-pagefind-title='Installation &amp; Usage'>",
            "<h2>Installation and usage</h2>",
            "</section>",
        ]);

        assert_eq!(
            data.anchor_titles.get("0:usage"),
            Some(&"Installation & Usage".to_owned())
        );
    }

    #[test]
    fn block_tag_formatting() {
        let data = test_parse(vec![
            "<p>Sentences should have periods</p>",
            "<p>Unless one exists.</p>",
            "<div>Or it ends with punctuation:</div>",
            "<article>Except for 'quotes'</article>",
        ]);

        assert_eq!(
            data.digest,
            "Sentences should have periods. Unless one exists. Or it ends with punctuation: Except for 'quotes'."
        )
    }

    #[test]
    fn description_list_formatting() {
        let data = test_parse(vec![
            "<dl>",
            "<dt>Morgawr</dt>",
            "<dd>A sea serpent</dd>",
            "<dt>Owlman:</dt>",
            "<dd>A giant owl-like creature</dd>",
            "</dl>",
        ]);

        assert_eq!(
            data.digest,
            "Morgawr: A sea serpent. Owlman: A giant owl-like creature."
        )
    }

    #[test]
    fn inline_tag_formatting() {
        let data = test_parse(vec![
            "<p>Inline tags like <span>span</span>",
            " and <b>bol",
            "d</b> shouldn't have periods</p>",
            "<p>And should n<i>o</i>t add any space.</p>",
        ]);

        assert_eq!(
            data.digest,
            "Inline tags like span and bold shouldn't have periods. And should not add any space."
        )
    }

    #[test]
    fn ignored_elements() {
        let data = test_parse(vec![
            "<p>Elements like:</p>",
            "<form>Should <b>not</b> be indexed</form>",
            "<p>forms</p>",
            "<div> As well as <div data-pagefind-ignore=''>",
            "Manually ignored <p>Elements</p></div>",
            "*crickets*</div>",
        ]);

        assert_eq!(data.digest, "Elements like: forms. As well as *crickets*.");
    }

    #[test]
    fn return_metadata() {
        let data = test_raw_parse(vec![
            "<html><head>",
            "<meta data-pagefind-meta='image[content]' content='/kitty.jpg' property='og:image'>",
            "</head><body>",
            "<div data-pagefind-meta='type:post'></div>",
            "<h1 data-pagefind-meta='headline'>Hello World</h1>",
            "<div>This post is <span data-pagefind-meta='adj'>hella</span> good.</div>",
            "<img data-pagefind-meta='hero[src]' src='/huzzah.png'>",
            "</body></html>",
        ]);

        assert_eq!(data.meta.get("image"), Some(&"/kitty.jpg".to_owned()));
        assert_eq!(data.meta.get("type"), Some(&"post".to_owned()));
        assert_eq!(data.meta.get("headline"), Some(&"Hello World".to_owned()));
        assert_eq!(data.meta.get("adj"), Some(&"hella".to_owned()));
        assert_eq!(data.meta.get("hero"), Some(&"/huzzah.png".to_owned()));
    }

    #[test]
    fn return_complex_metadata() {
        let data = test_raw_parse(vec![
            "<html><body>",
            "<img data-pagefind-meta='cat[src], cat-alt[alt]' src='/cat.png' alt='cat pic'>",
            "<h1 class='why?' data-pagefind-meta='headline, classname[class]'>Hello World</h1>",
            "<div data-pagefind-meta='self[data-pagefind-meta], type:post'></div>",
            "<div data-pagefind-meta='incorrect:post, self[data-pagefind-meta]'></div>",
            "</body></html>",
        ]);

        assert_eq!(data.meta.get("cat"), Some(&"/cat.png".to_owned()));
        assert_eq!(data.meta.get("cat-alt"), Some(&"cat pic".to_owned()));
        assert_eq!(data.meta.get("headline"), Some(&"Hello World".to_owned()));
        assert_eq!(data.meta.get("classname"), Some(&"why?".to_owned()));
        assert_eq!(
            data.meta.get("self"),
            Some(&"self[data-pagefind-meta], type:post".to_owned())
        );
        assert_eq!(data.meta.get("type"), Some(&"post".to_owned()));
        assert_eq!(
            data.meta.get("incorrect"),
            Some(&"post, self[data-pagefind-meta]".to_owned())
        );
    }
}