aimem-core 0.1.0

//! 4-layer memory stack — mirrors Python's layers.py.
//!
//! ```text
//! L0  Identity        (~100 tokens)   Always loaded — identity.txt
//! L1  Essential Story (~500-800 tok)  Top drawers from the palace
//! L2  On-Demand       (~200-500 tok)  Wing/room filtered retrieval
//! L3  Deep Search     (unlimited)     Turso vector_distance_cos semantic search
//! ```

use std::collections::HashMap;
use std::path::Path;

use thiserror::Error;

use crate::{
    config::Config,
    db::{DbError, PalaceDb},
    embedder::Embedder,
    search::{SearchError, Searcher},
    types::Drawer,
};

#[derive(Debug, Error)]
pub enum LayerError {
    #[error("db: {0}")]
    Db(#[from] DbError),
    #[error("search: {0}")]
    Search(#[from] SearchError),
    #[error("io: {0}")]
    Io(#[from] std::io::Error),
}

// ── L0 — Identity ────────────────────────────────────────────────────────────

/// Layer 0: identity text (~100 tokens, always loaded).
pub async fn l0_render(identity_path: &Path) -> String {
    if identity_path.exists() {
        match tokio::fs::read_to_string(identity_path).await {
            Ok(text) => return text.trim().to_string(),
            Err(_) => {}
        }
    }
    "## L0 — IDENTITY\nNo identity configured. Create ~/.aimem/identity.txt".to_string()
}

// ── L1 — Essential Story ─────────────────────────────────────────────────────

const L1_MAX_DRAWERS: usize = 15;
const L1_MAX_CHARS: usize = 3200;

/// Layer 1: top drawers from the palace, grouped by room (~500-800 tokens).
pub async fn l1_generate(db: &PalaceDb, wing: Option<&str>) -> Result<String, LayerError> {
    let drawers = db.fetch_drawers(wing, None, 200).await?;

    if drawers.is_empty() {
        return Ok("## L1 — No memories yet.".to_string());
    }

    // Group by room, take top L1_MAX_DRAWERS
    let mut by_room: HashMap<String, Vec<Drawer>> = HashMap::new();
    for d in drawers.into_iter().take(L1_MAX_DRAWERS) {
        by_room.entry(d.room.clone()).or_default().push(d);
    }

    let mut lines = vec!["## L1 — ESSENTIAL STORY".to_string()];
    let mut total_len = 0usize;

    let mut rooms: Vec<_> = by_room.iter().collect();
    rooms.sort_by_key(|(r, _)| r.as_str());

    for (room, entries) in rooms {
        let room_line = format!("\n[{}]", room);
        lines.push(room_line.clone());
        total_len += room_line.len();

        for d in entries {
            let snippet: String = d
                .content
                .trim()
                .replace('\n', " ")
                .chars()
                .take(200)
                .collect();
            let snippet = if d.content.len() > 200 {
                format!("{}...", snippet)
            } else {
                snippet
            };

            let source_tag = d
                .source_file
                .as_deref()
                .and_then(|s| Path::new(s).file_name())
                .map(|n| format!("  ({})", n.to_string_lossy()))
                .unwrap_or_default();

            let entry = format!("  - {}{}", snippet, source_tag);

            if total_len + entry.len() > L1_MAX_CHARS {
                lines.push("  ... (more in L3 search)".to_string());
                return Ok(lines.join("\n"));
            }
            total_len += entry.len();
            lines.push(entry);
        }
    }

    Ok(lines.join("\n"))
}

// ── L2 — On-Demand ───────────────────────────────────────────────────────────

/// Layer 2: on-demand wing/room filtered retrieval (~200-500 tokens).
pub async fn l2_retrieve(
    db: &PalaceDb,
    wing: Option<&str>,
    room: Option<&str>,
    n: usize,
) -> Result<String, LayerError> {
    let drawers = db.fetch_drawers(wing, room, n).await?;

    if drawers.is_empty() {
        let label = match (wing, room) {
            (Some(w), Some(r)) => format!("wing={w} room={r}"),
            (Some(w), None) => format!("wing={w}"),
            (None, Some(r)) => format!("room={r}"),
            (None, None) => "all".to_string(),
        };
        return Ok(format!("No drawers found for {label}."));
    }

    let mut lines = vec![format!("## L2 — ON-DEMAND ({} drawers)", drawers.len())];
    for d in &drawers {
        let snippet: String = d
            .content
            .trim()
            .replace('\n', " ")
            .chars()
            .take(300)
            .collect();
        let snippet = if d.content.len() > 300 {
            format!("{}...", snippet)
        } else {
            snippet
        };
        let source_tag = d
            .source_file
            .as_deref()
            .and_then(|s| Path::new(s).file_name())
            .map(|n| format!("  ({})", n.to_string_lossy()))
            .unwrap_or_default();
        lines.push(format!("  [{}] {}{}", d.room, snippet, source_tag));
    }
    Ok(lines.join("\n"))
}

// ── L3 — Deep Search ─────────────────────────────────────────────────────────

/// Layer 3: full semantic search via Turso `vector_distance_cos`.
pub async fn l3_search(
    searcher: &Searcher,
    query: &str,
    wing: Option<&str>,
    room: Option<&str>,
    n: usize,
) -> Result<String, LayerError> {
    let results = searcher.vector_search(query, wing, room, n).await?;

    if results.is_empty() {
        return Ok("No results found.".to_string());
    }

    let mut lines = vec![format!("## L3 — SEARCH RESULTS for \"{}\"", query)];
    for (i, r) in results.iter().enumerate() {
        let snippet: String = r
            .drawer
            .content
            .trim()
            .replace('\n', " ")
            .chars()
            .take(300)
            .collect();
        let snippet = if r.drawer.content.len() > 300 {
            format!("{}...", snippet)
        } else {
            snippet
        };
        let source = r
            .drawer
            .source_file
            .as_deref()
            .and_then(|s| Path::new(s).file_name())
            .map(|n| n.to_string_lossy().to_string())
            .unwrap_or_default();

        lines.push(format!(
            "  [{}] {}/{} (sim={:.3})",
            i + 1,
            r.drawer.wing,
            r.drawer.room,
            r.similarity,
        ));
        lines.push(format!("      {}", snippet));
        if !source.is_empty() {
            lines.push(format!("      src: {}", source));
        }
    }
    Ok(lines.join("\n"))
}

// ── MemoryStack — unified interface ──────────────────────────────────────────

/// Full 4-layer memory stack.
///
/// ```rust,no_run
/// use aimem_core::{PalaceDb, Config, Embedder, MemoryStack};
/// # async fn run() -> anyhow::Result<()> {
/// let cfg = Config::load()?;
/// let db = PalaceDb::open(&cfg.db_path).await?;
/// let embedder = Embedder::new()?;
/// let stack = MemoryStack::new(db, embedder, &cfg);
///
/// println!("{}", stack.wake_up(None).await?);
/// println!("{}", stack.recall(Some("my_project"), None).await?);
/// println!("{}", stack.search("pricing discussion", None, None).await?);
/// # Ok(())
/// # }
/// ```
#[derive(Debug, Clone)]
pub struct MemoryStack {
    db: PalaceDb,
    searcher: Searcher,
    identity_path: std::path::PathBuf,
}

impl MemoryStack {
    pub fn new(db: PalaceDb, embedder: Embedder, cfg: &Config) -> Self {
        let searcher = Searcher::new(db.clone(), embedder);
        Self {
            db,
            searcher,
            identity_path: cfg.identity_path.clone(),
        }
    }

    /// Generate wake-up context: L0 (identity) + L1 (essential story).
    /// ~600-900 tokens total. Inject into system prompt or first message.
    pub async fn wake_up(&self, wing: Option<&str>) -> Result<String, LayerError> {
        let l0 = l0_render(&self.identity_path).await;
        let l1 = l1_generate(&self.db, wing).await?;
        Ok(format!("{}\n\n{}", l0, l1))
    }

    /// On-demand L2 retrieval filtered by wing/room.
    pub async fn recall(
        &self,
        wing: Option<&str>,
        room: Option<&str>,
    ) -> Result<String, LayerError> {
        l2_retrieve(&self.db, wing, room, 10).await
    }

    /// Deep L3 semantic search.
    pub async fn search(
        &self,
        query: &str,
        wing: Option<&str>,
        room: Option<&str>,
    ) -> Result<String, LayerError> {
        l3_search(&self.searcher, query, wing, room, 5).await
    }

    /// Status of the whole stack.
    pub async fn status(&self) -> Result<serde_json::Value, LayerError> {
        let count = self.db.drawer_count().await?;
        let (wings, rooms) = self.db.taxonomy().await?;
        let l0_exists = self.identity_path.exists();
        let l0_tokens = if l0_exists {
            std::fs::read_to_string(&self.identity_path)
                .map(|s| s.len() / 4)
                .unwrap_or(0)
        } else {
            0
        };

        Ok(serde_json::json!({
            "total_drawers": count,
            "identity_path": self.identity_path.display().to_string(),
            "identity_exists": l0_exists,
            "identity_tokens_est": l0_tokens,
            "wings": wings.into_iter().map(|(w, c)| serde_json::json!({"wing": w, "count": c})).collect::<Vec<_>>(),
            "rooms": rooms.into_iter().map(|(r, c)| serde_json::json!({"room": r, "count": c})).collect::<Vec<_>>(),
        }))
    }
}