Allow AI interactions to be proxied through Zed's server so you don't need an API key (#7367)

Co-authored-by: Antonio <antonio@zed.dev>

Resurrected this from some assistant work I did in Spring of 2023.
- [x] Resurrect streaming responses
- [x] Use streaming responses to enable AI via Zed's servers by default
(but preserve API key option for now)
- [x] Simplify protobuf
- [x] Proxy to OpenAI on zed.dev
- [x] Proxy to Gemini on zed.dev
- [x] Improve UX for switching between openAI and google models
- We current disallow cycling when setting a custom model, but we need a
better solution to keep OpenAI models available while testing the google
ones
- [x] Show remaining tokens correctly for Google models
- [x] Remove semantic index
- [x] Delete `ai` crate
- [x] Cloud front so we can ban abuse
- [x] Rate-limiting
- [x] Fix panic when using inline assistant
- [x] Double check the upgraded `AssistantSettings` are
backwards-compatible
- [x] Add hosted LLM interaction behind a `language-models` feature
flag.

Release Notes:

- We are temporarily removing the semantic index in order to redesign it
from scratch.

---------

Co-authored-by: Antonio <antonio@zed.dev>
Co-authored-by: Antonio Scandurra <me@as-cii.com>
Co-authored-by: Thorsten <thorsten@zed.dev>
Co-authored-by: Max <max@zed.dev>

crates/open_ai/Cargo.toml

@@ -0,0 +1,19 @@
+[package]
+name = "open_ai"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+path = "src/open_ai.rs"
+
+[features]
+default = []
+schemars = ["dep:schemars"]
+
+[dependencies]
+anyhow.workspace = true
+futures.workspace = true
+schemars = { workspace = true, optional = true }
+serde.workspace = true
+serde_json.workspace = true
+util.workspace = true

crates/open_ai/src/open_ai.rs

@@ -0,0 +1,182 @@
+use anyhow::{anyhow, Result};
+use futures::{io::BufReader, stream::BoxStream, AsyncBufReadExt, AsyncReadExt, StreamExt};
+use serde::{Deserialize, Serialize};
+use std::convert::TryFrom;
+use util::http::{AsyncBody, HttpClient, Method, Request as HttpRequest};
+
+#[derive(Clone, Copy, Serialize, Deserialize, Debug, Eq, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum Role {
+    User,
+    Assistant,
+    System,
+}
+
+impl TryFrom<String> for Role {
+    type Error = anyhow::Error;
+
+    fn try_from(value: String) -> Result<Self> {
+        match value.as_str() {
+            "user" => Ok(Self::User),
+            "assistant" => Ok(Self::Assistant),
+            "system" => Ok(Self::System),
+            _ => Err(anyhow!("invalid role '{value}'")),
+        }
+    }
+}
+
+impl From<Role> for String {
+    fn from(val: Role) -> Self {
+        match val {
+            Role::User => "user".to_owned(),
+            Role::Assistant => "assistant".to_owned(),
+            Role::System => "system".to_owned(),
+        }
+    }
+}
+
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+#[derive(Clone, Debug, Default, Serialize, Deserialize, PartialEq)]
+pub enum Model {
+    #[serde(rename = "gpt-3.5-turbo", alias = "gpt-3.5-turbo-0613")]
+    ThreePointFiveTurbo,
+    #[serde(rename = "gpt-4", alias = "gpt-4-0613")]
+    Four,
+    #[serde(rename = "gpt-4-turbo-preview", alias = "gpt-4-1106-preview")]
+    #[default]
+    FourTurbo,
+}
+
+impl Model {
+    pub fn from_id(id: &str) -> Result<Self> {
+        match id {
+            "gpt-3.5-turbo" => Ok(Self::ThreePointFiveTurbo),
+            "gpt-4" => Ok(Self::Four),
+            "gpt-4-turbo-preview" => Ok(Self::FourTurbo),
+            _ => Err(anyhow!("invalid model id")),
+        }
+    }
+
+    pub fn id(&self) -> &'static str {
+        match self {
+            Self::ThreePointFiveTurbo => "gpt-3.5-turbo",
+            Self::Four => "gpt-4",
+            Self::FourTurbo => "gpt-4-turbo-preview",
+        }
+    }
+
+    pub fn display_name(&self) -> &'static str {
+        match self {
+            Self::ThreePointFiveTurbo => "gpt-3.5-turbo",
+            Self::Four => "gpt-4",
+            Self::FourTurbo => "gpt-4-turbo",
+        }
+    }
+}
+
+#[derive(Debug, Serialize)]
+pub struct Request {
+    pub model: Model,
+    pub messages: Vec<RequestMessage>,
+    pub stream: bool,
+    pub stop: Vec<String>,
+    pub temperature: f32,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct RequestMessage {
+    pub role: Role,
+    pub content: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
+pub struct ResponseMessage {
+    pub role: Option<Role>,
+    pub content: Option<String>,
+}
+
+#[derive(Deserialize, Debug)]
+pub struct Usage {
+    pub prompt_tokens: u32,
+    pub completion_tokens: u32,
+    pub total_tokens: u32,
+}
+
+#[derive(Deserialize, Debug)]
+pub struct ChoiceDelta {
+    pub index: u32,
+    pub delta: ResponseMessage,
+    pub finish_reason: Option<String>,
+}
+
+#[derive(Deserialize, Debug)]
+pub struct ResponseStreamEvent {
+    pub created: u32,
+    pub model: String,
+    pub choices: Vec<ChoiceDelta>,
+    pub usage: Option<Usage>,
+}
+
+pub async fn stream_completion(
+    client: &dyn HttpClient,
+    api_url: &str,
+    api_key: &str,
+    request: Request,
+) -> Result<BoxStream<'static, Result<ResponseStreamEvent>>> {
+    let uri = format!("{api_url}/chat/completions");
+    let request = HttpRequest::builder()
+        .method(Method::POST)
+        .uri(uri)
+        .header("Content-Type", "application/json")
+        .header("Authorization", format!("Bearer {}", api_key))
+        .body(AsyncBody::from(serde_json::to_string(&request)?))?;
+    let mut response = client.send(request).await?;
+    if response.status().is_success() {
+        let reader = BufReader::new(response.into_body());
+        Ok(reader
+            .lines()
+            .filter_map(|line| async move {
+                match line {
+                    Ok(line) => {
+                        let line = line.strip_prefix("data: ")?;
+                        if line == "[DONE]" {
+                            None
+                        } else {
+                            match serde_json::from_str(line) {
+                                Ok(response) => Some(Ok(response)),
+                                Err(error) => Some(Err(anyhow!(error))),
+                            }
+                        }
+                    }
+                    Err(error) => Some(Err(anyhow!(error))),
+                }
+            })
+            .boxed())
+    } else {
+        let mut body = String::new();
+        response.body_mut().read_to_string(&mut body).await?;
+
+        #[derive(Deserialize)]
+        struct OpenAiResponse {
+            error: OpenAiError,
+        }
+
+        #[derive(Deserialize)]
+        struct OpenAiError {
+            message: String,
+        }
+
+        match serde_json::from_str::<OpenAiResponse>(&body) {
+            Ok(response) if !response.error.message.is_empty() => Err(anyhow!(
+                "Failed to connect to OpenAI API: {}",
+                response.error.message,
+            )),
+
+            _ => Err(anyhow!(
+                "Failed to connect to OpenAI API: {} {}",
+                response.status(),
+                body,
+            )),
+        }
+    }
+}