openai-api-rs 10.0.1

use crate::v1::chat_completion::{Reasoning, ReasoningEffort, Tool, ToolCall, ToolChoiceType};
use crate::{
    impl_builder_methods,
    v1::chat_completion::{serialize_tool_choice, ChatCompletionMessage},
};

use futures_util::Stream;
use serde::{Deserialize, Serialize};
use serde_json::Value;
use std::collections::HashMap;
use std::pin::Pin;
use std::task::{Context, Poll};

#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct ChatCompletionStreamRequest {
    pub model: String,
    pub messages: Vec<ChatCompletionMessage>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub temperature: Option<f64>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub top_p: Option<f64>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub n: Option<i64>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub response_format: Option<Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub stop: Option<Vec<String>>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub max_tokens: Option<i64>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub presence_penalty: Option<f64>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub frequency_penalty: Option<f64>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub logit_bias: Option<HashMap<String, i32>>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub user: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub seed: Option<i64>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub tools: Option<Vec<Tool>>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub parallel_tool_calls: Option<bool>,
    #[serde(skip_serializing_if = "Option::is_none")]
    #[serde(serialize_with = "serialize_tool_choice")]
    pub tool_choice: Option<ToolChoiceType>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reasoning: Option<Reasoning>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reasoning_effort: Option<ReasoningEffort>,
    /// Optional list of transforms to apply to the chat completion request.
    ///
    /// Transforms allow modifying the request before it's sent to the API,
    /// enabling features like prompt rewriting, content filtering, or other
    /// preprocessing steps. When None, no transforms are applied.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub transforms: Option<Vec<String>>,
}

impl ChatCompletionStreamRequest {
    pub fn new(model: String, messages: Vec<ChatCompletionMessage>) -> Self {
        Self {
            model,
            messages,
            temperature: None,
            top_p: None,
            n: None,
            response_format: None,
            stop: None,
            max_tokens: None,
            presence_penalty: None,
            frequency_penalty: None,
            logit_bias: None,
            user: None,
            seed: None,
            tools: None,
            parallel_tool_calls: None,
            tool_choice: None,
            reasoning: None,
            reasoning_effort: None,
            transforms: None,
        }
    }
}

impl_builder_methods!(
    ChatCompletionStreamRequest,
    temperature: f64,
    top_p: f64,
    n: i64,
    response_format: Value,
    stop: Vec<String>,
    max_tokens: i64,
    presence_penalty: f64,
    frequency_penalty: f64,
    logit_bias: HashMap<String, i32>,
    user: String,
    seed: i64,
    tools: Vec<Tool>,
    parallel_tool_calls: bool,
    tool_choice: ToolChoiceType,
    reasoning: Reasoning,
    reasoning_effort: ReasoningEffort,
    transforms: Vec<String>
);

#[derive(Debug, Clone)]
pub enum ChatCompletionStreamResponse {
    Content(String),
    Reasoning(String),
    ToolCall(Vec<ToolCall>),
    Done,
}

pub struct ChatCompletionStream<S: Stream<Item = Result<bytes::Bytes, reqwest::Error>> + Unpin> {
    pub response: S,
    pub buffer: String,
    pub first_chunk: bool,
}

impl<S> ChatCompletionStream<S>
where
    S: Stream<Item = Result<bytes::Bytes, reqwest::Error>> + Unpin,
{
    fn find_event_delimiter(buffer: &str) -> Option<(usize, usize)> {
        let carriage_idx = buffer.find("\r\n\r\n");
        let newline_idx = buffer.find("\n\n");

        match (carriage_idx, newline_idx) {
            (Some(r_idx), Some(n_idx)) => {
                if r_idx <= n_idx {
                    Some((r_idx, 4))
                } else {
                    Some((n_idx, 2))
                }
            }
            (Some(r_idx), None) => Some((r_idx, 4)),
            (None, Some(n_idx)) => Some((n_idx, 2)),
            (None, None) => None,
        }
    }

    fn next_response_from_buffer(&mut self) -> Option<ChatCompletionStreamResponse> {
        while let Some((idx, delimiter_len)) = Self::find_event_delimiter(&self.buffer) {
            let event = self.buffer[..idx].to_owned();
            self.buffer = self.buffer[idx + delimiter_len..].to_owned();

            let mut data_payload = String::new();
            for line in event.lines() {
                let trimmed_line = line.trim_end_matches('\r');
                if let Some(content) = trimmed_line
                    .strip_prefix("data: ")
                    .or_else(|| trimmed_line.strip_prefix("data:"))
                {
                    if !content.is_empty() {
                        if !data_payload.is_empty() {
                            data_payload.push('\n');
                        }
                        data_payload.push_str(content);
                    }
                }
            }

            if data_payload.is_empty() {
                continue;
            }

            if data_payload == "[DONE]" {
                return Some(ChatCompletionStreamResponse::Done);
            }

            match serde_json::from_str::<Value>(&data_payload) {
                Ok(json) => {
                    if let Some(delta) = json
                        .get("choices")
                        .and_then(|choices| choices.get(0))
                        .and_then(|choice| choice.get("delta"))
                    {
                        if let Some(tool_call_response) = delta
                            .get("tool_calls")
                            .and_then(|tool_calls| tool_calls.as_array())
                            .map(|tool_calls_array| {
                                tool_calls_array
                                    .iter()
                                    .filter_map(|v| serde_json::from_value(v.clone()).ok())
                                    .collect::<Vec<ToolCall>>()
                            })
                            .filter(|tool_calls_vec| !tool_calls_vec.is_empty())
                            .map(ChatCompletionStreamResponse::ToolCall)
                        {
                            return Some(tool_call_response);
                        }

                        if let Some(reasoning) = delta
                            .get("reasoning")
                            .or_else(|| delta.get("reasoning_content"))
                            .and_then(|r| r.as_str())
                        {
                            let output = reasoning.replace("\\n", "\n");
                            return Some(ChatCompletionStreamResponse::Reasoning(output));
                        }

                        if let Some(content) = delta.get("content").and_then(|c| c.as_str()) {
                            let output = content.replace("\\n", "\n");
                            return Some(ChatCompletionStreamResponse::Content(output));
                        }
                    }
                }
                Err(error) => {
                    eprintln!("Failed to parse SSE chunk as JSON: {}", error);
                }
            }
        }

        None
    }
}

impl<S: Stream<Item = Result<bytes::Bytes, reqwest::Error>> + Unpin> Stream
    for ChatCompletionStream<S>
{
    type Item = ChatCompletionStreamResponse;

    fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
        loop {
            if let Some(response) = self.next_response_from_buffer() {
                return Poll::Ready(Some(response));
            }

            match Pin::new(&mut self.as_mut().response).poll_next(cx) {
                Poll::Ready(Some(Ok(chunk))) => {
                    let chunk_str = String::from_utf8_lossy(&chunk).to_string();

                    if self.first_chunk {
                        self.first_chunk = false;
                    }
                    self.buffer.push_str(&chunk_str);
                }
                Poll::Ready(Some(Err(error))) => {
                    eprintln!("Error in stream: {:?}", error);
                    return Poll::Ready(None);
                }
                Poll::Ready(None) => {
                    return Poll::Ready(None);
                }
                Poll::Pending => {
                    return Poll::Pending;
                }
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use crate::v1::chat_completion::{ReasoningEffort, ReasoningSummary};

    use super::*;
    use serde_json::json;

    #[test]
    fn test_reasoning_effort_serialization() {
        let reasoning = Reasoning {
            effort: Some(ReasoningEffort::High),
            summary: Some(ReasoningSummary::Detailed),
        };

        let serialized = serde_json::to_value(&reasoning).unwrap();
        let expected = json!({
            "effort": "high",
            "summary": "detailed"
        });

        assert_eq!(serialized, expected);
    }

    #[test]
    fn test_reasoning_summary_only_serialization() {
        let reasoning = Reasoning {
            effort: None,
            summary: Some(ReasoningSummary::Auto),
        };

        let serialized = serde_json::to_value(&reasoning).unwrap();
        let expected = json!({
            "summary": "auto"
        });

        assert_eq!(serialized, expected);
    }

    #[test]
    fn test_reasoning_deserialization() {
        let json_str = r#"{"effort": "medium", "summary": "concise"}"#;
        let reasoning: Reasoning = serde_json::from_str(json_str).unwrap();
        assert_eq!(reasoning.effort, Some(ReasoningEffort::Medium));
        assert_eq!(reasoning.summary, Some(ReasoningSummary::Concise));
    }

    #[test]
    fn test_chat_completion_request_with_reasoning() {
        let mut req = ChatCompletionStreamRequest::new("gpt-4".to_string(), vec![]);

        req.reasoning = Some(Reasoning {
            effort: Some(ReasoningEffort::Low),
            summary: Some(ReasoningSummary::Auto),
        });

        let serialized = serde_json::to_value(&req).unwrap();
        assert_eq!(serialized["reasoning"]["effort"], "low");
        assert_eq!(serialized["reasoning"]["summary"], "auto");
    }

    #[test]
    fn test_chat_completion_stream_request_with_reasoning_effort() {
        let mut req = ChatCompletionStreamRequest::new("gpt-5.1".to_string(), vec![]);
        req.reasoning_effort = Some(ReasoningEffort::None);

        let serialized = serde_json::to_value(&req).unwrap();
        assert_eq!(serialized["reasoning_effort"], "none");
    }

    #[test]
    fn test_transforms_none_serialization() {
        let req = ChatCompletionStreamRequest::new("gpt-4".to_string(), vec![]);
        let serialised = serde_json::to_value(&req).unwrap();
        // Verify that the transforms field is completely omitted from JSON output
        assert!(!serialised.as_object().unwrap().contains_key("transforms"));
    }

    #[test]
    fn test_transforms_some_serialization() {
        let mut req = ChatCompletionStreamRequest::new("gpt-4".to_string(), vec![]);
        req.transforms = Some(vec!["transform1".to_string(), "transform2".to_string()]);
        let serialised = serde_json::to_value(&req).unwrap();
        // Verify that the transforms field is included as a proper JSON array
        assert_eq!(
            serialised["transforms"],
            serde_json::json!(["transform1", "transform2"])
        );
    }

    #[test]
    fn test_transforms_some_deserialization() {
        let json_str =
            r#"{"model": "gpt-4", "messages": [], "transforms": ["transform1", "transform2"]}"#;
        let req: ChatCompletionStreamRequest = serde_json::from_str(json_str).unwrap();
        // Verify that the transforms field is properly populated with Some(vec)
        assert_eq!(
            req.transforms,
            Some(vec!["transform1".to_string(), "transform2".to_string()])
        );
    }

    #[test]
    fn test_transforms_none_deserialization() {
        let json_str = r#"{"model": "gpt-4", "messages": []}"#;
        let req: ChatCompletionStreamRequest = serde_json::from_str(json_str).unwrap();
        // Verify that the transforms field is properly set to None when absent
        assert_eq!(req.transforms, None);
    }

    #[test]
    fn test_transforms_builder_method() {
        let transforms = vec!["transform1".to_string(), "transform2".to_string()];
        let req = ChatCompletionStreamRequest::new("gpt-4".to_string(), vec![])
            .transforms(transforms.clone());
        // Verify that the transforms field is properly set through the builder method
        assert_eq!(req.transforms, Some(transforms));
    }

    #[test]
    fn test_reasoning_effort_builder_method() {
        let req = ChatCompletionStreamRequest::new("gpt-5.1".to_string(), vec![])
            .reasoning_effort(ReasoningEffort::Xhigh);
        assert_eq!(req.reasoning_effort, Some(ReasoningEffort::Xhigh));
    }

    #[test]
    fn test_stream_reasoning_delta() {
        let mut stream = ChatCompletionStream {
            response: futures_util::stream::empty(),
            buffer: "data: {\"choices\":[{\"delta\":{\"reasoning\":\"step 1\"}}]}\n\n".to_string(),
            first_chunk: false,
        };

        let response = stream.next_response_from_buffer();
        match response {
            Some(ChatCompletionStreamResponse::Reasoning(reasoning)) => {
                assert_eq!(reasoning, "step 1");
            }
            _ => panic!("Expected reasoning delta"),
        }
    }
}