// compare.rs — F7 compare: for each assistant response in the current
// context, regenerate with a configured test model and emit pairs for
// side-by-side review.

use std::sync::Arc;

use crate::agent::api::ApiClient;
use crate::agent::context::{
    AstNode, Role, render_branch_text, render_prior_context,
};
use crate::mind::{MindState, MindTriggered, TaskHandle};
use crate::subconscious::generate::gen_continuation;
use crate::subconscious::learn::node_timestamp_ns;

#[derive(Clone, Debug)]
pub struct CompareCandidate {
    pub entry_idx: usize,
    pub original_text: String,
    pub alternate_text: String,
    pub prior_context: String,
    pub timestamp_ns: i64,
}

pub struct CompareScoring {
    agent: Arc<crate::agent::Agent>,
    shared: Arc<std::sync::Mutex<MindState>>,
    task: TaskHandle,
}

impl CompareScoring {
    pub fn new(
        agent: Arc<crate::agent::Agent>,
        shared: Arc<std::sync::Mutex<MindState>>,
    ) -> Self {
        Self { agent, shared, task: TaskHandle::new() }
    }
}

impl MindTriggered for CompareScoring {
    fn trigger(&self) {
        self.task.trigger(run(self.agent.clone(), self.shared.clone()));
    }
}

fn resolve_test_client() -> Result<ApiClient, String> {
    let cfg = crate::config::app();
    let name = cfg.compare.test_backend.clone();
    if name.is_empty() {
        return Err("compare.test_backend not set in config".to_string());
    }
    let r = cfg.resolve_model(&name).map_err(|e| format!("{:#}", e))?;
    Ok(ApiClient::new(&r.api_base, &r.api_key, &r.model_id))
}

async fn run(
    agent: Arc<crate::agent::Agent>,
    shared: Arc<std::sync::Mutex<MindState>>,
) {
    {
        let mut s = shared.lock().unwrap();
        s.compare_candidates.clear();
        s.compare_error = None;
    }
    agent.state.lock().await.changed.notify_one();

    let activity = crate::agent::start_activity(&agent, "compare: scoring...").await;

    let test_client = match resolve_test_client() {
        Ok(c) => c,
        Err(e) => {
            shared.lock().unwrap().compare_error = Some(e);
            agent.state.lock().await.changed.notify_one();
            return;
        }
    };

    let context = agent.context.lock().await.clone();
    let entries = context.conversation();
    let responses: Vec<usize> = entries.iter().enumerate()
        .filter(|(_, n)| matches!(n, AstNode::Branch { role: Role::Assistant, .. }))
        .map(|(i, _)| i).collect();

    for (i, entry_idx) in responses.iter().copied().enumerate() {
        activity.update(format!("compare: {}/{}", i + 1, responses.len())).await;

        let node = &entries[entry_idx];
        let original_text = match node {
            AstNode::Branch { children, .. } => render_branch_text(children),
            _ => continue,
        };
        if original_text.trim().is_empty() { continue; }

        let alternate_text = match
            gen_continuation(&context, entry_idx, |_| false, &test_client).await
        {
            Ok(t) => t,
            Err(e) => { dbglog!("[compare] gen failed at {}: {:#}", entry_idx, e); continue; }
        };

        shared.lock().unwrap().compare_candidates.push(CompareCandidate {
            entry_idx,
            original_text,
            alternate_text,
            prior_context: render_prior_context(entries, entry_idx, 2),
            timestamp_ns: node_timestamp_ns(node),
        });
        if let Ok(st) = agent.state.try_lock() { st.changed.notify_one(); }
    }
}