lc-core 0.9.0

use async_trait::async_trait;
use futures_util::Stream;
use std::pin::Pin;

use super::base::{BaseOutputParser, OutputParserError, OutputParserResult};
use crate::runnables::{Runnable, RunnableConfig};

/// 逗号分隔列表输出解析器
///
/// 将 LLM 输出的逗号分隔文本解析为字符串列表。
/// 支持中文逗号（，）和英文逗号（,）。
/// 自动去除每个项目的空白字符和空项目。
///
/// 相当于 Python LangChain 的 `CommaSeparatedListOutputParser`。
///
/// # 示例
/// ```ignore
/// use langchainrust::output_parsers::CommaSeparatedListOutputParser;
///
/// let parser = CommaSeparatedListOutputParser::new();
/// let result = parser.parse("apple, banana, cherry").await?;
/// assert_eq!(result, vec!["apple", "banana", "cherry"]);
/// ```
pub struct CommaSeparatedListOutputParser;

impl CommaSeparatedListOutputParser {
    pub fn new() -> Self {
        Self
    }
}

impl Default for CommaSeparatedListOutputParser {
    fn default() -> Self {
        Self::new()
    }
}

#[async_trait]
impl BaseOutputParser<Vec<String>> for CommaSeparatedListOutputParser {
    async fn parse(&self, text: &str) -> OutputParserResult<Vec<String>> {
        let text = text.trim();
        if text.is_empty() {
            return Ok(Vec::new());
        }

        // 支持中文逗号和英文逗号
        let items: Vec<String> = text
            .split(',')
            .flat_map(|item| item.split('，'))
            .map(|s| s.trim().to_string())
            .filter(|s| !s.is_empty())
            .collect();

        Ok(items)
    }

    fn get_format_instructions(&self) -> String {
        "请用逗号分隔的列表形式输出，例如：项目1, 项目2, 项目3".to_string()
    }
}

#[async_trait]
impl Runnable<String, Vec<String>> for CommaSeparatedListOutputParser {
    type Error = OutputParserError;

    async fn invoke(
        &self,
        input: String,
        _config: Option<RunnableConfig>,
    ) -> Result<Vec<String>, Self::Error> {
        self.parse(&input).await
    }

    async fn stream(
        &self,
        input: String,
        _config: Option<RunnableConfig>,
    ) -> Result<Pin<Box<dyn Stream<Item = Result<Vec<String>, Self::Error>> + Send>>, Self::Error>
    {
        let result = self.parse(&input).await?;
        let stream = futures_util::stream::once(async move { Ok(result) });
        Ok(Box::pin(stream))
    }
}