git-ai 1.2.0

use anyhow::Result;
use async_openai::config::OpenAIConfig;
use async_openai::types::chat::{
  ChatCompletionMessageToolCalls, ChatCompletionNamedToolChoice, ChatCompletionRequestSystemMessageArgs, ChatCompletionRequestUserMessageArgs, ChatCompletionToolChoiceOption, ChatCompletionTools, CreateChatCompletionRequestArgs
};
use async_openai::Client;

use crate::function_calling::{create_commit_function_tool, CommitFunctionArgs};
use crate::debug_output;

/// Simplified multi-step commit message generation that works with raw diff
pub async fn generate_commit_message_simple(
  client: &Client<OpenAIConfig>, model: &str, diff_content: &str, max_length: Option<usize>
) -> Result<String> {
  log::info!("Starting simplified multi-step commit message generation");

  // Initialize multi-step debug session
  if let Some(session) = debug_output::debug_session() {
    session.init_multi_step_debug();
  }

  // Use the commit function tool directly with the full diff
  let tools = vec![ChatCompletionTools::Function(create_commit_function_tool(max_length)?)];

  let system_message = ChatCompletionRequestSystemMessageArgs::default()
    .content(
      "You are a git commit message expert. Analyze the provided git diff and generate a concise, \
       descriptive commit message. Focus on the most significant changes and their impact. \
       The message should explain WHAT changed and WHY it matters."
    )
    .build()?
    .into();

  let user_message = ChatCompletionRequestUserMessageArgs::default()
    .content(format!("Generate a commit message for the following git diff:\n\n{diff_content}"))
    .build()?
    .into();

  let request = CreateChatCompletionRequestArgs::default()
    .model(model)
    .messages(vec![system_message, user_message])
    .tools(tools)
    .tool_choice(ChatCompletionToolChoiceOption::Function(ChatCompletionNamedToolChoice::from("commit")))
    .build()?;

  let response = client.chat().create(request).await?;

  let tool_call_arguments = first_function_call_arguments(&response);

  if let Some(arguments) = tool_call_arguments {
    let args: CommitFunctionArgs = serde_json::from_str(arguments)?;

    // Record in debug session
    if let Some(session) = debug_output::debug_session() {
      session.set_commit_result(args.message.clone(), args.reasoning.clone());
      session.set_files_analyzed(args.clone());
      // Set a dummy count since we're not parsing files
      session.set_total_files_parsed(1);
    }

    Ok(args.message)
  } else {
    anyhow::bail!("No tool call in response")
  }
}

/// Extracts the arguments of the first function tool call from a chat completion response.
///
/// Uses `.choices.first()` instead of `choices[0]` indexing so that an empty `choices`
/// array (which the OpenAI API can legally return) yields `None` rather than panicking.
/// Callers treat `None` as "no tool call" and return a clean error.
fn first_function_call_arguments(response: &async_openai::types::chat::CreateChatCompletionResponse) -> Option<&str> {
  response
    .choices
    .first()?
    .message
    .tool_calls
    .as_ref()
    .and_then(|calls| calls.first())
    .and_then(|call| {
      match call {
        ChatCompletionMessageToolCalls::Function(f) => Some(f.function.arguments.as_str()),
        _ => None
      }
    })
}

/// Local version that doesn't require parsing
pub fn generate_commit_message_simple_local(diff_content: &str, max_length: Option<usize>) -> Result<String> {
  log::info!("Starting simplified local commit message generation");

  // Count basic statistics from the diff
  let mut lines_added = 0;
  let mut lines_removed = 0;
  let mut files_mentioned = std::collections::HashSet::new();

  for line in diff_content.lines() {
    if line.starts_with("+++") || line.starts_with("---") {
      if let Some(file) = line.split_whitespace().nth(1) {
        files_mentioned.insert(file.trim_start_matches("a/").trim_start_matches("b/"));
      }
    } else if line.starts_with('+') && !line.starts_with("+++") {
      lines_added += 1;
    } else if line.starts_with('-') && !line.starts_with("---") {
      lines_removed += 1;
    }
  }

  // Track in debug session
  if let Some(session) = debug_output::debug_session() {
    session.set_total_files_parsed(files_mentioned.len());
  }

  // Generate a simple commit message based on the diff
  let message = match files_mentioned.len().cmp(&1) {
    std::cmp::Ordering::Equal => {
      let file = files_mentioned
        .iter()
        .next()
        .ok_or_else(|| anyhow::anyhow!("No files mentioned in commit message"))?;
      if lines_added > 0 && lines_removed == 0 {
        format!(
          "Add {} to {}",
          if lines_added == 1 {
            "content"
          } else {
            "new content"
          },
          file
        )
      } else if lines_removed > 0 && lines_added == 0 {
        format!("Remove content from {file}")
      } else {
        format!("Update {file}")
      }
    }
    std::cmp::Ordering::Greater => format!("Update {} files", files_mentioned.len()),
    std::cmp::Ordering::Less => "Update files".to_string()
  };

  // Ensure it fits within the length limit
  let max_len = max_length.unwrap_or(72);
  if message.len() > max_len {
    Ok(message.chars().take(max_len - 3).collect::<String>() + "...")
  } else {
    Ok(message)
  }
}

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

  /// C2: An OpenAI response with an empty `choices` array must not panic. The extracted
  /// helper returns `None` (callers then produce a clean error) instead of indexing
  /// `choices[0]`.
  #[test]
  fn test_first_function_call_arguments_empty_choices_no_panic() {
    let json = serde_json::json!({
      "id": "chatcmpl-test",
      "choices": [],
      "created": 0,
      "model": "gpt-4.1",
      "object": "chat.completion",
      "usage": null
    });
    let response: async_openai::types::chat::CreateChatCompletionResponse =
      serde_json::from_value(json).expect("should deserialize a response with empty choices");

    assert!(first_function_call_arguments(&response).is_none());
  }
}