//! Multi-step OpenAI-compatible tool-calling ReAct loop.

use crate::config::Config;
use crate::model::{ChatMessage, chat_completion};
use crate::tools::{ToolContext, execute_tool, tool_definitions};
use anyhow::Result;

pub const DEFAULT_MAX_ROUNDS: usize = 12;

pub const AGENT_SYSTEM: &str = "\
You are GrokBoy, a concise local coding assistant with tools.
Use tools when they help solve the task; otherwise answer directly.
Prefer short, clear answers. Traditional Chinese is welcome when the user writes in Chinese.
Available tools: shell, list_dir, read_file, write_file.
Do not invent tool results — call the tools. Stop when you can give a final answer.";

/// Run the agent loop until the model returns text without tool_calls or max rounds.
/// Appends all intermediate messages (assistant tool_calls + tool results + final) to `messages`.
/// Returns the final assistant text (may be empty if stopped on round limit with only tools).
pub async fn run_agent(
    config: &Config,
    messages: &mut Vec<ChatMessage>,
    tool_ctx: &ToolContext,
    max_rounds: usize,
) -> Result<String> {
    let tools = tool_definitions();
    let mut last_text = String::new();

    for _round in 0..max_rounds {
        let reply = chat_completion(config, messages, Some(&tools)).await?;
        let tool_calls = reply.tool_calls.clone().unwrap_or_default();

        if tool_calls.is_empty() {
            last_text = reply.text().to_string();
            messages.push(reply);
            return Ok(last_text);
        }

        // Keep any content the model sent alongside tool_calls.
        if let Some(c) = reply.content.as_ref().filter(|s| !s.is_empty()) {
            last_text = c.clone();
        }
        messages.push(reply);

        for call in &tool_calls {
            let result = execute_tool(tool_ctx, &call.function.name, &call.function.arguments).await;
            messages.push(ChatMessage::tool(&call.id, result));
        }
    }

    Ok(last_text)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn system_prompt_mentions_tools() {
        assert!(AGENT_SYSTEM.contains("shell"));
        assert!(AGENT_SYSTEM.contains("Traditional Chinese") || AGENT_SYSTEM.contains("Chinese"));
    }

    #[test]
    fn default_max_rounds_is_12() {
        assert_eq!(DEFAULT_MAX_ROUNDS, 12);
    }
}