//! brain_local.rs — In-process Brain singleton (stoneshell-brain)
//! Copyright 2026 Joseph Stone - All Rights Reserved
//!
//! Replaces ALL run_brain() subprocess calls with direct Candle+LMDB calls.
//! Zero subprocesses. Zero API tokens. Self-contained on device.
//!
//! Collections:
//!   "default"        — general knowledge + RAG indexed content
//!   "flint_episodic" — FLINT conversation Q+A pairs (runtime memory)
//!   "flint_training" — gate training signals indexed for FLINT learning
//!   "flint_knowledge"— curated knowledge FLINT can reference
//!   "spf_source"     — SPF src/*.rs indexed at startup (FLINT reads its own code)

use std::path::PathBuf;
use std::sync::{LazyLock, Mutex};
use stoneshell_brain::{Brain, BrainConfig};
use crate::paths::spf_root;

// ── Global singleton ─────────────────────────────────────────────────────────

static BRAIN: LazyLock<Mutex<Option<Brain>>> =
    LazyLock::new(|| Mutex::new(None));

// ── Config ───────────────────────────────────────────────────────────────────

fn brain_config() -> BrainConfig {
    let base = spf_root().join("LIVE/TMP/stoneshell-brain");
    BrainConfig {
        model_path: base.join("models/all-MiniLM-L6-v2").to_string_lossy().to_string(),
        storage_path: base.join("storage").to_string_lossy().to_string(),
        docs_path: spf_root().join("LIVE/BRAIN/DOCS").to_string_lossy().to_string(),
        embedding_dim: 384,
        chunk_size: 512,
        chunk_overlap: 64,
        top_k: 20, // generous — handlers truncate to requested limit
        threshold: 0.3,
    }
}

// ── Init ─────────────────────────────────────────────────────────────────────

/// Initialize the brain singleton. Call once at startup (run/run_worker).
/// Non-fatal — if model fails to load, brain returns error strings but SPF keeps running.
/// RC-1: Retries up to 3 times with 2s delay to handle transient failures
/// (model file locked, LMDB contention during startup race).
pub fn init_brain() {
    const MAX_RETRIES: u32 = 3;
    const RETRY_DELAY: std::time::Duration = std::time::Duration::from_secs(2);

    for attempt in 1..=MAX_RETRIES {
        let config = brain_config();
        match Brain::new(config) {
            Ok(mut brain) => {
                match brain.load_model() {
                    Ok(()) => log::info!("Brain: MiniLM-L6-v2 loaded — stoneshell-brain active"),
                    Err(e) => log::error!("Brain: model load failed (search disabled): {}", e),
                }
                *BRAIN.lock().unwrap() = Some(brain);
                return;
            }
            Err(e) => {
                if attempt < MAX_RETRIES {
                    log::warn!("Brain: init attempt {}/{} failed: {} — retrying", attempt, MAX_RETRIES, e);
                    std::thread::sleep(RETRY_DELAY);
                } else {
                    log::error!("Brain: init failed after {} attempts: {}", MAX_RETRIES, e);
                }
            }
        }
    }
}

/// Index knowledge/ directory into "flint_knowledge" collection.
/// Drop any .md or .txt file there — FLINT reads it on next startup.
/// Skipped if collection already has content (idempotent on restart).
pub fn index_knowledge_docs() {
    let knowledge_dir = spf_root().join("LIVE/TMP/stoneshell-brain/knowledge");
    if !knowledge_dir.exists() {
        return; // no knowledge dir yet — silent skip
    }

    let mut lock = BRAIN.lock().unwrap();
    let Some(ref mut brain) = *lock else {
        return;
    };

    // Skip if already indexed
    if let Ok(stats) = brain.collection_stats("flint_knowledge") {
        if stats.document_count > 0 {
            log::info!("Brain: flint_knowledge already has {} chunks — skipping re-index", stats.document_count);
            return;
        }
    }

    match brain.index_directory(&knowledge_dir, "flint_knowledge", &["md", "txt"]) {
        Ok(stats) => log::info!(
            "Brain: indexed {} knowledge docs ({} chunks) → flint_knowledge",
            stats.files_indexed, stats.chunks_created
        ),
        Err(e) => log::warn!("Brain: flint_knowledge index failed: {}", e),
    }
}

/// Index SPF source code into "spf_source" collection.
/// Skipped if collection already has content (idempotent on restart).
pub fn index_spf_sources() {
    let src_dir = spf_root().join("src");
    if !src_dir.exists() {
        log::warn!("Brain: src/ not found at {:?} — spf_source skipped", src_dir);
        return;
    }

    let mut lock = BRAIN.lock().unwrap();
    let Some(ref mut brain) = *lock else {
        return;
    };

    // Skip if already indexed
    if let Ok(stats) = brain.collection_stats("spf_source") {
        if stats.document_count > 0 {
            log::info!("Brain: spf_source already has {} chunks — skipping re-index", stats.document_count);
            return;
        }
    }

    match brain.index_directory(&src_dir, "spf_source", &["rs"]) {
        Ok(stats) => log::info!(
            "Brain: indexed {} src files ({} chunks) → spf_source",
            stats.files_indexed, stats.chunks_created
        ),
        Err(e) => log::warn!("Brain: spf_source index failed: {}", e),
    }
}

// ── Public wrappers — one per MCP handler ───────────────────────────────────

/// spf_brain_search — vector similarity search, returns formatted results
pub fn brain_search(query: &str, collection: &str, limit: usize) -> String {
    let lock = BRAIN.lock().unwrap();
    let Some(ref brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    match brain.search(query, collection) {
        Ok(results) => {
            if results.is_empty() {
                return format!("No results for '{}' in '{}'", query, collection);
            }
            let take = limit.min(results.len());
            let mut out = format!("Brain search '{}' — {} result(s):\n\n", query, take);
            for r in results.iter().take(take) {
                out.push_str(&format!(
                    "Score: {:.3} | {}\n{}\n\n",
                    r.score, r.source, r.text
                ));
            }
            out
        }
        Err(e) => format!("Brain search error: {}", e),
    }
}

/// spf_brain_store — chunk + embed + store arbitrary text
pub fn brain_store(text: &str, title: &str, collection: &str) -> String {
    let mut lock = BRAIN.lock().unwrap();
    let Some(ref mut brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    match brain.store_document(text, title, collection) {
        Ok(count) => format!("Stored '{}' → {} chunk(s) in '{}'", title, count, collection),
        Err(e) => format!("Brain store error: {}", e),
    }
}

/// spf_brain_context — hybrid search, returns formatted context for prompt injection
pub fn brain_context(query: &str, collection: &str, max_tokens: usize) -> String {
    let lock = BRAIN.lock().unwrap();
    let Some(ref brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    match brain.get_context(query, collection, max_tokens) {
        Ok(ctx) if ctx.is_empty() => format!("No context found for '{}'", query),
        Ok(ctx) => ctx,
        Err(e) => format!("Brain context error: {}", e),
    }
}

/// spf_brain_index — index a file or directory into a collection
pub fn brain_index_path(path: &str, collection: &str) -> String {
    let mut lock = BRAIN.lock().unwrap();
    let Some(ref mut brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    let p = PathBuf::from(path);
    if p.is_dir() {
        match brain.index_directory(&p, collection, &[]) {
            Ok(stats) => format!(
                "Indexed directory '{}': {} files, {} chunks ({} failed)",
                path, stats.files_indexed, stats.chunks_created, stats.files_failed
            ),
            Err(e) => format!("Brain index error: {}", e),
        }
    } else {
        match brain.index_file(&p, collection) {
            Ok(count) => format!("Indexed '{}': {} chunks", path, count),
            Err(e) => format!("Brain index error: {}", e),
        }
    }
}

/// spf_brain_list — list all collections with doc counts
pub fn brain_list_collections() -> String {
    let lock = BRAIN.lock().unwrap();
    let Some(ref brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    match brain.list_collections() {
        Ok(cols) if cols.is_empty() => "No collections found".to_string(),
        Ok(cols) => {
            let mut out = format!("{} collection(s):\n\n", cols.len());
            for col in &cols {
                match brain.collection_stats(col) {
                    Ok(s) => out.push_str(&format!("  {} — {} docs, {}d\n", col, s.document_count, s.embedding_dim)),
                    Err(_) => out.push_str(&format!("  {}\n", col)),
                }
            }
            out
        }
        Err(e) => format!("Brain list error: {}", e),
    }
}

/// spf_brain_status — model state, storage size, collections summary
pub fn brain_status() -> String {
    let base = spf_root().join("LIVE/TMP/stoneshell-brain");
    let lock = BRAIN.lock().unwrap();
    let mut parts = Vec::new();

    match &*lock {
        Some(brain) => {
            parts.push(format!("Status: active"));
            parts.push(format!("Model: {}", if brain.is_model_loaded() { "loaded ✓" } else { "not loaded ✗" }));
            parts.push(format!("Model path: {}", base.join("models/all-MiniLM-L6-v2").display()));
            parts.push(format!("Storage: {}", base.join("storage").display()));

            let storage = base.join("storage");
            if storage.exists() {
                if let Ok(entries) = std::fs::read_dir(&storage) {
                    let size: u64 = entries
                        .filter_map(|e| e.ok())
                        .filter_map(|e| e.metadata().ok())
                        .map(|m| m.len())
                        .sum();
                    parts.push(format!("Storage size: {:.2} MB", size as f64 / 1_048_576.0));
                }
            }

            match brain.list_collections() {
                Ok(cols) if cols.is_empty() => parts.push("Collections: (none)".to_string()),
                Ok(cols) => {
                    let col_lines: Vec<String> = cols.iter().map(|c| {
                        brain.collection_stats(c)
                            .map(|s| format!("  {} ({} docs)", c, s.document_count))
                            .unwrap_or_else(|_| format!("  {}", c))
                    }).collect();
                    parts.push(format!("Collections:\n{}", col_lines.join("\n")));
                }
                Err(e) => parts.push(format!("Collections: error — {}", e)),
            }
        }
        None => {
            parts.push("Status: NOT INITIALIZED".to_string());
            parts.push(format!("Expected model at: {}", base.join("models/all-MiniLM-L6-v2").display()));
        }
    }

    parts.join("\n")
}

/// spf_brain_recall — search + return grouped full text by source
pub fn brain_recall(query: &str, collection: &str) -> String {
    let lock = BRAIN.lock().unwrap();
    let Some(ref brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    match brain.search(query, collection) {
        Ok(results) if results.is_empty() => {
            format!("No documents found for '{}'", query)
        }
        Ok(results) => {
            let mut out = format!("Recall '{}' ({} chunks):\n", query, results.len());
            let mut current_source = String::new();
            for r in &results {
                if r.source != current_source {
                    out.push_str(&format!("\n══ {} ══\n", r.source));
                    current_source = r.source.clone();
                }
                out.push_str(&r.text);
                out.push('\n');
            }
            out
        }
        Err(e) => format!("Brain recall error: {}", e),
    }
}

/// spf_brain_list_docs — doc count + summary for a collection
pub fn brain_list_docs(collection: &str) -> String {
    let lock = BRAIN.lock().unwrap();
    let Some(ref brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    match brain.collection_stats(collection) {
        Ok(stats) => format!(
            "Collection '{}': {} document chunk(s), {}d embeddings",
            collection, stats.document_count, stats.embedding_dim
        ),
        Err(e) => format!("Brain list-docs error: {}", e),
    }
}

/// spf_brain_get_doc — find chunk by ID or source name match
pub fn brain_get_doc(doc_id: &str, collection: &str) -> String {
    let lock = BRAIN.lock().unwrap();
    let Some(ref brain) = *lock else {
        return "Brain not initialized".to_string();
    };
    // Search using the doc_id as a query, then find exact or partial match
    match brain.search(doc_id, collection) {
        Ok(results) => {
            if let Some(r) = results
                .into_iter()
                .find(|r| r.id == doc_id || r.source.contains(doc_id))
            {
                format!(
                    "ID: {}\nSource: {}\nScore: {:.3}\n\n{}",
                    r.id, r.source, r.score, r.text
                )
            } else {
                format!("Doc '{}' not found in '{}'", doc_id, collection)
            }
        }
        Err(e) => format!("Brain get-doc error: {}", e),
    }
}