✨ feat(engine): `mojeek` for the search engine (#464)

* 🧑‍💻 fix: add closing curly brace in the nix build step

* ✨ feat: add code to provide search results from `mojeek` engine

---------

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

flake.nix

@@ -60,4 +60,4 @@
       # calls the build function
       packages.websurfx = packages.default;
     });
-
+}

src/engines/mod.rs

@@ -6,6 +6,7 @@
 pub mod brave;
 pub mod duckduckgo;
 pub mod librex;
+pub mod mojeek;
 pub mod search_result_parser;
 pub mod searx;
 pub mod startpage;

src/engines/mojeek.rs

@@ -0,0 +1,151 @@
+//! The `mojeek` module handles the scraping of results from the mojeek search engine
+//! by querying the upstream mojeek search engine with user provided query and with a page
+//! number if provided.
+
+use std::collections::HashMap;
+
+use reqwest::header::HeaderMap;
+use reqwest::Client;
+use scraper::Html;
+
+use crate::models::aggregation_models::SearchResult;
+
+use crate::models::engine_models::{EngineError, SearchEngine};
+
+use error_stack::{Report, Result, ResultExt};
+
+use super::search_result_parser::SearchResultParser;
+
+/// A new Mojeek engine type defined in-order to implement the `SearchEngine` trait which allows to
+/// reduce code duplication as well as allows to create vector of different search engines easily.
+pub struct Mojeek {
+    /// The parser, used to interpret the search result.
+    parser: SearchResultParser,
+}
+
+impl Mojeek {
+    /// Creates the Mojeek parser.
+    pub fn new() -> Result<Self, EngineError> {
+        Ok(Self {
+            parser: SearchResultParser::new(
+                ".result-col",
+                ".results-standard li",
+                "a span.url",
+                "h2 a.title",
+                "p.s",
+            )?,
+        })
+    }
+}
+
+#[async_trait::async_trait]
+impl SearchEngine for Mojeek {
+    async fn results(
+        &self,
+        query: &str,
+        page: u32,
+        user_agent: &str,
+        client: &Client,
+        safe_search: u8,
+    ) -> Result<HashMap<String, SearchResult>, EngineError> {
+        // Mojeek uses `start results from this number` convention
+        // So, for 10 results per page, page 0 starts at 1, page 1
+        // starts at 11, and so on.
+        let results_per_page = 10;
+        let start_result = results_per_page * page + 1;
+
+        let results_per_page = results_per_page.to_string();
+        let start_result = start_result.to_string();
+
+        let search_engines = vec![
+            "Bing",
+            "Brave",
+            "DuckDuckGo",
+            "Ecosia",
+            "Google",
+            "Lilo",
+            "Metager",
+            "Qwant",
+            "Startpage",
+            "Swisscows",
+            "Yandex",
+            "Yep",
+            "You",
+        ];
+        let qss = search_engines.join("%2C");
+        let safe = if safe_search == 0 { "0" } else { "1" };
+
+        // Mojeek detects automated requests, these are preferences that are
+        // able to circumvent the countermeasure. Some of these are
+        // not documented in their Search API
+        let query_params: Vec<(&str, &str)> = vec![
+            ("t", results_per_page.as_str()),
+            ("theme", "dark"),
+            ("arc", "none"),
+            ("date", "1"),
+            ("cdate", "1"),
+            ("tlen", "100"),
+            ("ref", "1"),
+            ("hp", "minimal"),
+            ("lb", "en"),
+            ("qss", &qss),
+            ("safe", safe),
+        ];
+
+        let mut query_params_string = String::new();
+        for (k, v) in &query_params {
+            query_params_string.push_str(&format!("&{k}={v}"));
+        }
+
+        let url: String = match page {
+            0 => {
+                format!("https://www.mojeek.com/search?q={query}{query_params_string}")
+            }
+            _ => {
+                format!(
+                    "https://www.mojeek.com/search?q={query}&s={start_result}{query_params_string}"
+                )
+            }
+        };
+
+        let mut cookie_string = String::new();
+        for (k, v) in &query_params {
+            cookie_string.push_str(&format!("{k}={v}; "));
+        }
+
+        let header_map = HeaderMap::try_from(&HashMap::from([
+            ("USER_AGENT".to_string(), user_agent.to_string()),
+            ("REFERER".to_string(), "https://google.com/".to_string()),
+            (
+                "CONTENT_TYPE".to_string(),
+                "application/x-www-form-urlencoded".to_string(),
+            ),
+            ("COOKIE".to_string(), cookie_string),
+        ]))
+        .change_context(EngineError::UnexpectedError)?;
+
+        let document: Html = Html::parse_document(
+            &Mojeek::fetch_html_from_upstream(self, &url, header_map, client).await?,
+        );
+
+        if let Some(no_result_msg) = self.parser.parse_for_no_results(&document).nth(0) {
+            if no_result_msg
+                .inner_html()
+                .contains("No pages found matching:")
+            {
+                return Err(Report::new(EngineError::EmptyResultSet));
+            }
+        }
+
+        // scrape all the results from the html
+        self.parser
+            .parse_for_results(&document, |title, url, desc| {
+                Some(SearchResult::new(
+                    title.inner_html().trim(),
+                    url.inner_html().trim(),
+                    desc.inner_html().trim(),
+                    &["mojeek"],
+                ))
+            })
+    }
+}

src/models/engine_models.rs

@@ -162,6 +162,10 @@ impl EngineHandler {
                     let engine = crate::engines::librex::LibreX::new()?;
                     ("librex", Box::new(engine))
                 }
+                "mojeek" => {
+                    let engine = crate::engines::mojeek::Mojeek::new()?;
+                    ("mojeek", Box::new(engine))
+                }
                 _ => {
                     return Err(Report::from(EngineError::NoSuchEngineFound(
                         engine_name.to_string(),

websurfx/config.lua

@@ -64,4 +64,5 @@ upstream_search_engines = {
     Brave = false,
     Startpage = false,
     LibreX = false,
+    Mojeek = false,
 } -- select the upstream search engines from which the results should be fetched.