agent2: Port more tools (#35987)

Release Notes:

- N/A

---------

Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>
Co-authored-by: Antonio Scandurra <me@as-cii.com>

crates/agent2/src/tools/fetch_tool.rs

@@ -0,0 +1,161 @@
+use std::rc::Rc;
+use std::sync::Arc;
+use std::{borrow::Cow, cell::RefCell};
+
+use agent_client_protocol as acp;
+use anyhow::{Context as _, Result, bail};
+use futures::AsyncReadExt as _;
+use gpui::{App, AppContext as _, Task};
+use html_to_markdown::{TagHandler, convert_html_to_markdown, markdown};
+use http_client::{AsyncBody, HttpClientWithUrl};
+use schemars::JsonSchema;
+use serde::{Deserialize, Serialize};
+use ui::SharedString;
+use util::markdown::MarkdownEscaped;
+
+use crate::{AgentTool, ToolCallEventStream};
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy)]
+enum ContentType {
+    Html,
+    Plaintext,
+    Json,
+}
+
+/// Fetches a URL and returns the content as Markdown.
+#[derive(Debug, Serialize, Deserialize, JsonSchema)]
+pub struct FetchToolInput {
+    /// The URL to fetch.
+    url: String,
+}
+
+pub struct FetchTool {
+    http_client: Arc<HttpClientWithUrl>,
+}
+
+impl FetchTool {
+    pub fn new(http_client: Arc<HttpClientWithUrl>) -> Self {
+        Self { http_client }
+    }
+
+    async fn build_message(http_client: Arc<HttpClientWithUrl>, url: &str) -> Result<String> {
+        let url = if !url.starts_with("https://") && !url.starts_with("http://") {
+            Cow::Owned(format!("https://{url}"))
+        } else {
+            Cow::Borrowed(url)
+        };
+
+        let mut response = http_client.get(&url, AsyncBody::default(), true).await?;
+
+        let mut body = Vec::new();
+        response
+            .body_mut()
+            .read_to_end(&mut body)
+            .await
+            .context("error reading response body")?;
+
+        if response.status().is_client_error() {
+            let text = String::from_utf8_lossy(body.as_slice());
+            bail!(
+                "status error {}, response: {text:?}",
+                response.status().as_u16()
+            );
+        }
+
+        let Some(content_type) = response.headers().get("content-type") else {
+            bail!("missing Content-Type header");
+        };
+        let content_type = content_type
+            .to_str()
+            .context("invalid Content-Type header")?;
+
+        let content_type = if content_type.starts_with("text/plain") {
+            ContentType::Plaintext
+        } else if content_type.starts_with("application/json") {
+            ContentType::Json
+        } else {
+            ContentType::Html
+        };
+
+        match content_type {
+            ContentType::Html => {
+                let mut handlers: Vec<TagHandler> = vec![
+                    Rc::new(RefCell::new(markdown::WebpageChromeRemover)),
+                    Rc::new(RefCell::new(markdown::ParagraphHandler)),
+                    Rc::new(RefCell::new(markdown::HeadingHandler)),
+                    Rc::new(RefCell::new(markdown::ListHandler)),
+                    Rc::new(RefCell::new(markdown::TableHandler::new())),
+                    Rc::new(RefCell::new(markdown::StyledTextHandler)),
+                ];
+                if url.contains("wikipedia.org") {
+                    use html_to_markdown::structure::wikipedia;
+
+                    handlers.push(Rc::new(RefCell::new(wikipedia::WikipediaChromeRemover)));
+                    handlers.push(Rc::new(RefCell::new(wikipedia::WikipediaInfoboxHandler)));
+                    handlers.push(Rc::new(
+                        RefCell::new(wikipedia::WikipediaCodeHandler::new()),
+                    ));
+                } else {
+                    handlers.push(Rc::new(RefCell::new(markdown::CodeHandler)));
+                }
+
+                convert_html_to_markdown(&body[..], &mut handlers)
+            }
+            ContentType::Plaintext => Ok(std::str::from_utf8(&body)?.to_owned()),
+            ContentType::Json => {
+                let json: serde_json::Value = serde_json::from_slice(&body)?;
+
+                Ok(format!(
+                    "```json\n{}\n```",
+                    serde_json::to_string_pretty(&json)?
+                ))
+            }
+        }
+    }
+}
+
+impl AgentTool for FetchTool {
+    type Input = FetchToolInput;
+    type Output = String;
+
+    fn name(&self) -> SharedString {
+        "fetch".into()
+    }
+
+    fn kind(&self) -> acp::ToolKind {
+        acp::ToolKind::Fetch
+    }
+
+    fn initial_title(&self, input: Result<Self::Input, serde_json::Value>) -> SharedString {
+        match input {
+            Ok(input) => format!("Fetch {}", MarkdownEscaped(&input.url)).into(),
+            Err(_) => "Fetch URL".into(),
+        }
+    }
+
+    fn run(
+        self: Arc<Self>,
+        input: Self::Input,
+        event_stream: ToolCallEventStream,
+        cx: &mut App,
+    ) -> Task<Result<Self::Output>> {
+        let text = cx.background_spawn({
+            let http_client = self.http_client.clone();
+            async move { Self::build_message(http_client, &input.url).await }
+        });
+
+        cx.foreground_executor().spawn(async move {
+            let text = text.await?;
+            if text.trim().is_empty() {
+                bail!("no textual content found");
+            }
+
+            event_stream.update_fields(acp::ToolCallUpdateFields {
+                content: Some(vec![text.clone().into()]),
+                ..Default::default()
+            });
+
+            Ok(text)
+        })
+    }
+}