git-ca 0.1.0

git plugin that drafts commit messages using GitHub Copilot
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pub mod prompt;

use crate::copilot::Client;
use crate::error::Result;

/// Default model used when neither `--model` nor `config.default_model` is set.
pub const FALLBACK_MODEL: &str = "gpt-4o";

pub async fn generate(client: &Client, model: &str, diff: &str) -> Result<String> {
    let messages = prompt::build(diff);
    let text = client.chat(model, &messages).await?;
    Ok(strip_code_fences(&text))
}

/// Some models wrap commit messages in ``` fences despite the system prompt.
/// Strip a single outer fence if present; leave inner backticks alone.
fn strip_code_fences(s: &str) -> String {
    let trimmed = s.trim();
    if let Some(rest) = trimmed.strip_prefix("```") {
        // drop an optional language tag on the opening fence
        let after_lang = rest.split_once('\n').map(|(_, body)| body).unwrap_or(rest);
        if let Some(body) = after_lang.strip_suffix("```") {
            return body.trim().to_string();
        }
        if let Some(body) = after_lang.rsplit_once("\n```").map(|(b, _)| b) {
            return body.trim().to_string();
        }
    }
    trimmed.to_string()
}

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

    #[test]
    fn strips_triple_backtick_fence() {
        let s = "```\nfeat: x\n\nbody\n```";
        assert_eq!(strip_code_fences(s), "feat: x\n\nbody");
    }

    #[test]
    fn strips_fence_with_language_tag() {
        let s = "```text\nfix: y\n```";
        assert_eq!(strip_code_fences(s), "fix: y");
    }

    #[test]
    fn leaves_unfenced_message_alone() {
        let s = "refactor: z\n\nsome body";
        assert_eq!(strip_code_fences(s), s);
    }
}