// SPF Smart Gateway - Chat Engine (Block P)
// Copyright 2026 Joseph Stone - All Rights Reserved
//
// Text chat system for user ↔ user, user ↔ agent, agent ↔ agent communication.
// Messages flow over mesh StreamType::ChatText (0x02) and local LMDB storage.
// Transformer (Researcher config) generates responses in decoder-only/causal mode.
//
// Features:
//   - ChatMessage format with conversation tracking
//   - Conversation context window (last N messages as transformer input)
//   - Chat history persisted in agent_state LMDB
//   - Room-based routing (1:1 and group)
//   - MCP tool interfaces: spf_chat_send, spf_chat_history, spf_chat_rooms
//
// Depends on: transformer.rs (Block E), framing.rs (Block F, StreamType::ChatText)
// Storage: agent_state LMDB with "chat:" key prefix

use serde::{Deserialize, Serialize};
use std::collections::{HashMap, HashSet};

/// Block QQ: Rate limiter for FLINT auto-responses — max 1 per 5 seconds per peer
/// Uses Option<HashMap> because HashMap::new() is not const-compatible.
static FLINT_RATE_LIMIT: std::sync::Mutex<Option<HashMap<String, std::time::Instant>>>
    = std::sync::Mutex::new(None);

// ============================================================================
// CHAT MESSAGE FORMAT
// ============================================================================

/// A single chat message.
/// Serialized as JSON for mesh transport (framing StreamType::ChatText = 0x02)
/// and LMDB storage.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ChatMessage {
    /// Unique message ID (timestamp_ms + sender hash)
    pub id: String,
    /// Sender identifier (peer pub_key short hash or "user" or "system")
    pub from: String,
    /// Recipient ("all" for room broadcast, or specific peer short hash)
    pub to: String,
    /// Message text content
    pub text: String,
    /// Timestamp (RFC3339)
    pub timestamp: String,
    /// Conversation/room ID
    pub conversation_id: String,
    /// Message type
    pub msg_type: MessageType,
}

/// Message type classification
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum MessageType {
    /// Regular user text message
    UserText,
    /// Transformer-generated response
    AgentResponse,
    /// System notification (join, leave, error)
    System,
    /// Tool result shared in chat
    ToolResult,
}

// ============================================================================
// CONVERSATION TRACKING
// ============================================================================

/// A conversation (chat room) with message history and context window.
#[derive(Debug, Clone)]
pub struct Conversation {
    /// Unique conversation ID
    pub id: String,
    /// Display name for the conversation
    pub name: String,
    /// Participants (peer short hashes)
    pub participants: Vec<String>,
    /// Message history (chronological order)
    pub messages: Vec<ChatMessage>,
    /// Maximum messages to retain in memory (older ones in LMDB only)
    pub max_memory_messages: usize,
    /// Context window size for transformer input (last N messages)
    pub context_window: usize,
    /// Creation timestamp
    pub created: String,
    /// Last activity timestamp
    pub last_activity: String,
}

impl Conversation {
    /// Create a new conversation
    pub fn new(id: String, name: String, participants: Vec<String>, timestamp: String) -> Self {
        Self {
            id,
            name,
            participants,
            messages: Vec::new(),
            max_memory_messages: 500,
            context_window: 20,
            created: timestamp.clone(),
            last_activity: timestamp,
        }
    }

    /// Add a message to the conversation
    pub fn add_message(&mut self, msg: ChatMessage) {
        self.last_activity = msg.timestamp.clone();
        self.messages.push(msg);

        // Trim in-memory buffer if over limit
        if self.messages.len() > self.max_memory_messages {
            // Keep the most recent messages
            let drain_count = self.messages.len() - self.max_memory_messages;
            self.messages.drain(..drain_count);
        }
    }

    /// Get the last N messages for transformer context window
    pub fn context_messages(&self) -> &[ChatMessage] {
        let start = self.messages.len().saturating_sub(self.context_window);
        &self.messages[start..]
    }

    /// Format context messages as a single string for transformer input
    /// Format: "from: text\nfrom: text\n..."
    pub fn context_as_text(&self) -> String {
        self.context_messages()
            .iter()
            .map(|m| format!("{}: {}", m.from, m.text))
            .collect::<Vec<_>>()
            .join("\n")
    }

    /// Total message count (in memory)
    pub fn message_count(&self) -> usize {
        self.messages.len()
    }

    /// Check if a peer is a participant
    pub fn has_participant(&self, peer: &str) -> bool {
        self.participants.iter().any(|p| p == peer)
    }
}

// ============================================================================
// CHAT ENGINE
// ============================================================================

/// Central chat engine managing all conversations.
///
/// Handles:
/// - Routing messages to correct conversations
/// - Creating conversations on first contact
/// - Preparing transformer context for response generation
/// - LMDB persistence of chat history
pub struct ChatEngine {
    /// Active conversations indexed by ID
    conversations: Vec<Conversation>,
    /// Local identity (short pub_key hash)
    pub local_identity: String,
    /// Default context window size for new conversations
    pub default_context_window: usize,
}

impl ChatEngine {
    /// Create a new chat engine
    pub fn new(local_identity: String) -> Self {
        Self {
            conversations: Vec::new(),
            local_identity,
            default_context_window: 20,
        }
    }

    /// Process an incoming message. Creates conversation if needed.
    /// Returns the conversation ID the message was routed to.
    pub fn receive_message(&mut self, msg: ChatMessage) -> String {
        let conv_id = msg.conversation_id.clone();

        // Find or create conversation
        if !self.conversations.iter().any(|c| c.id == conv_id) {
            let participants = vec![msg.from.clone(), msg.to.clone()];
            let conv = Conversation::new(
                conv_id.clone(),
                format!("Chat with {}", msg.from),
                participants,
                msg.timestamp.clone(),
            );
            self.conversations.push(conv);
        }

        if let Some(conv) = self.conversations.iter_mut().find(|c| c.id == conv_id) {
            conv.add_message(msg);
        }

        conv_id
    }

    /// Create a new outgoing message
    pub fn create_message(
        &self,
        to: &str,
        text: &str,
        conversation_id: &str,
        timestamp: &str,
    ) -> ChatMessage {
        let id = format!("{}_{}", timestamp.replace([':', '-', 'T', 'Z'], ""),
            &self.local_identity[..8.min(self.local_identity.len())]);

        ChatMessage {
            id,
            from: self.local_identity.clone(),
            to: to.to_string(),
            text: text.to_string(),
            timestamp: timestamp.to_string(),
            conversation_id: conversation_id.to_string(),
            msg_type: MessageType::AgentResponse,
        }
    }

    /// Get context text for transformer input (for a given conversation)
    /// Returns None if conversation doesn't exist
    pub fn get_context(&self, conversation_id: &str) -> Option<String> {
        self.conversations.iter()
            .find(|c| c.id == conversation_id)
            .map(|c| c.context_as_text())
    }

    /// Get conversation by ID
    pub fn get_conversation(&self, id: &str) -> Option<&Conversation> {
        self.conversations.iter().find(|c| c.id == id)
    }

    /// List all active conversations
    pub fn list_conversations(&self) -> Vec<ConversationSummary> {
        self.conversations.iter().map(|c| ConversationSummary {
            id: c.id.clone(),
            name: c.name.clone(),
            participants: c.participants.clone(),
            message_count: c.message_count(),
            last_activity: c.last_activity.clone(),
        }).collect()
    }

    /// Get chat history for a conversation (last N messages)
    pub fn get_history(&self, conversation_id: &str, limit: usize) -> Vec<&ChatMessage> {
        match self.conversations.iter().find(|c| c.id == conversation_id) {
            Some(conv) => {
                let start = conv.messages.len().saturating_sub(limit);
                conv.messages[start..].iter().collect()
            }
            None => Vec::new(),
        }
    }

    /// Total conversations
    pub fn conversation_count(&self) -> usize {
        self.conversations.len()
    }

    /// Total messages across all conversations
    pub fn total_messages(&self) -> usize {
        self.conversations.iter().map(|c| c.message_count()).sum()
    }

    // ---- Block FF: LMDB Persistence ----

    /// Serialize all messages in a conversation as LMDB-ready key-value pairs.
    /// Returns Vec<(key, serialized_bytes)> for direct LMDB insertion.
    /// Caller (mcp.rs handler) performs the actual LMDB write.
    pub fn persist_conversation(&self, conversation_id: &str) -> Option<Vec<(String, Vec<u8>)>> {
        let conv = self.conversations.iter().find(|c| c.id == conversation_id)?;
        let pairs: Vec<(String, Vec<u8>)> = conv.messages.iter()
            .filter_map(|msg| {
                let key = message_key(conversation_id, &msg.id);
                serialize_message(msg).ok().map(|bytes| (key, bytes))
            })
            .collect();
        Some(pairs)
    }

    /// Load messages from serialized LMDB data into a conversation.
    /// Creates the conversation if it doesn't exist.
    /// Returns the number of messages successfully loaded.
    pub fn load_conversation_messages(
        &mut self,
        conversation_id: &str,
        name: &str,
        serialized_messages: &[(&str, Vec<u8>)],
    ) -> Result<usize, String> {
        if !self.conversations.iter().any(|c| c.id == conversation_id) {
            let timestamp = chrono::Utc::now().to_rfc3339();
            self.conversations.push(Conversation::new(
                conversation_id.to_string(),
                name.to_string(),
                Vec::new(),
                timestamp,
            ));
        }

        let conv = self.conversations.iter_mut()
            .find(|c| c.id == conversation_id)
            .ok_or_else(|| "Conversation not found after creation".to_string())?;

        let mut loaded = 0;
        for (_key, data) in serialized_messages {
            if let Ok(msg) = deserialize_message(data) {
                if !conv.participants.contains(&msg.from) {
                    conv.participants.push(msg.from.clone());
                }
                conv.add_message(msg);
                loaded += 1;
            }
        }

        Ok(loaded)
    }
}

/// Summary of a conversation (for listing)
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ConversationSummary {
    pub id: String,
    pub name: String,
    pub participants: Vec<String>,
    pub message_count: usize,
    pub last_activity: String,
}

// ============================================================================
// LMDB PERSISTENCE
// ============================================================================

/// Serialize a chat message for LMDB storage
pub fn serialize_message(msg: &ChatMessage) -> Result<Vec<u8>, String> {
    serde_json::to_vec(msg).map_err(|e| format!("Serialize error: {}", e))
}

/// Deserialize a chat message from LMDB storage
pub fn deserialize_message(data: &[u8]) -> Result<ChatMessage, String> {
    serde_json::from_slice(data).map_err(|e| format!("Deserialize error: {}", e))
}

/// LMDB key for a chat message
/// Format: "chat:conv:{conversation_id}:msg:{message_id}"
pub fn message_key(conversation_id: &str, message_id: &str) -> String {
    format!("chat:conv:{}:msg:{}", conversation_id, message_id)
}

/// LMDB key for conversation metadata
pub fn conversation_key(conversation_id: &str) -> String {
    format!("chat:conv:{}:meta", conversation_id)
}

/// LMDB key prefix for all messages in a conversation
pub fn conversation_prefix(conversation_id: &str) -> String {
    format!("chat:conv:{}:msg:", conversation_id)
}

/// LMDB key for chat engine metadata (conversation list)
pub fn chat_meta_key() -> &'static str {
    "chat:meta"
}

// ============================================================================
// MESH TRANSPORT HELPERS
// ============================================================================

/// Serialize a chat message for mesh transport (StreamType::ChatText = 0x02)
/// This is the payload that goes inside a framing::Frame
pub fn message_to_bytes(msg: &ChatMessage) -> Result<Vec<u8>, String> {
    serde_json::to_vec(msg).map_err(|e| format!("Serialize error: {}", e))
}

/// Deserialize a chat message received from mesh transport
pub fn message_from_bytes(data: &[u8]) -> Result<ChatMessage, String> {
    serde_json::from_slice(data).map_err(|e| format!("Deserialize error: {}", e))
}

// ============================================================================
// MESH STREAM HANDLER
// ============================================================================

/// Handle an incoming ChatText mesh frame.
/// Parses the ChatMessage from the frame payload, logs receipt,
/// and returns an acknowledgment frame. Zero silent drops.
///
/// Called from: mesh.rs stream_router() for StreamType::ChatText (0x02)
pub fn handle_mesh_chat(
    frame: &crate::framing::Frame,
    peer_key: &str,
    transformer: &Option<std::sync::Arc<std::sync::RwLock<crate::transformer_tools::TransformerState>>>,
) -> Option<crate::framing::Frame> {
    match message_from_bytes(&frame.payload) {
        Ok(msg) => {
            eprintln!("[SPF-CHAT] Received from {}: {} (conv: {})",
                &peer_key[..8.min(peer_key.len())],
                msg.text.chars().take(50).collect::<String>(),
                msg.conversation_id);

            // Block QQ: Check chat_enabled + rate limit before FLINT auto-response
            let should_respond = {
                let can_respond = transformer.as_ref().map_or(false, |t| {
                    let state = t.read().unwrap();
                    state.chat_enabled
                });
                if can_respond {
                    // Rate limit: max 1 FLINT response per 5 seconds per peer
                    let mut limiter = FLINT_RATE_LIMIT.lock().unwrap_or_else(|e| e.into_inner());
                    let limits = limiter.get_or_insert_with(HashMap::new);
                    let now = std::time::Instant::now();
                    let peer_id = peer_key.to_string();
                    if let Some(last) = limits.get(&peer_id) {
                        if now.duration_since(*last).as_secs() < 5 {
                            eprintln!("[{}] Rate limited for peer {}", FLINT_NAME,
                                &peer_key[..8.min(peer_key.len())]);
                            false
                        } else {
                            limits.insert(peer_id, now);
                            true
                        }
                    } else {
                        limits.insert(peer_id, now);
                        true
                    }
                } else {
                    false
                }
            };

            // Generate FLINT response with context injection + quality scoring (Block FF)
            // Block QQ: Only when chat_enabled=true AND rate limit allows
            let response_text = if should_respond {
                let flint_result = generate_flint_response(
                    &msg.text,
                    None, // Conversation context injected when ChatEngine wired to mesh
                    transformer,
                    true, // Use brain for context enrichment
                );
                flint_result.and_then(|r| {
                    match r.quality {
                        ResponseQuality::Accept { score } => {
                            eprintln!("[{}] Generated response (quality: {:.2}, ctx: {} tok, gen: {} tok)",
                                FLINT_NAME, score, r.context_tokens_used, r.generation_tokens);
                            Some(format!("[{}] {}", FLINT_NAME, r.text)) // Block QQ: prefix
                        }
                        ResponseQuality::Reject { reason, score } => {
                            eprintln!("[{}] Response rejected (score: {:.2}): {}",
                                FLINT_NAME, score, reason);
                            None
                        }
                    }
                })
            } else {
                None
            };

            let response = serde_json::json!({
                "type": "chat_response",
                "message_id": msg.id,
                "conversation_id": msg.conversation_id,
                "from": peer_key,
                "status": "received",
                "response": response_text.as_deref().unwrap_or(""),
                "generated": response_text.is_some(),
            });
            Some(crate::framing::Frame::chat(&response.to_string()))
        }
        Err(e) => {
            eprintln!("[SPF-CHAT] Failed to parse chat message from {}: {}", &peer_key[..8.min(peer_key.len())], e);
            let err = serde_json::json!({
                "type": "chat_error",
                "error": format!("Parse error: {}", e),
                "from": peer_key,
            });
            Some(crate::framing::Frame::chat(&err.to_string()))
        }
    }
}

// ============================================================================
// CALL SIGNALING — Voice call establishment over mesh (Block GG)
// ============================================================================

/// Voice call signal — sent via mesh to establish/teardown voice calls.
/// Transported as ChatMessage with msg_type = System and JSON signal payload.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum CallSignal {
    /// Initiate a voice call (caller → receiver)
    Ring { caller: String },
    /// Accept an incoming call (receiver → caller)
    Accept { callee: String },
    /// Reject an incoming call (receiver → caller)
    Reject { callee: String, reason: String },
    /// End an active call (either party)
    Hangup { from: String, reason: String },
}

impl CallSignal {
    /// Serialize to JSON string for mesh transport
    pub fn to_json(&self) -> String {
        serde_json::to_string(self).unwrap_or_default()
    }

    /// Deserialize from JSON string
    pub fn from_json(s: &str) -> Result<Self, String> {
        serde_json::from_str(s).map_err(|e| format!("CallSignal parse: {}", e))
    }

    /// Wrap this signal as a ChatMessage for mesh transport
    pub fn to_chat_message(&self, from: &str, to: &str, conversation_id: &str) -> ChatMessage {
        ChatMessage {
            id: format!("call_{}", chrono::Utc::now().timestamp_millis()),
            from: from.to_string(),
            to: to.to_string(),
            text: self.to_json(),
            timestamp: chrono::Utc::now().to_rfc3339(),
            conversation_id: conversation_id.to_string(),
            msg_type: MessageType::System,
        }
    }

    /// Check if a ChatMessage contains a call signal
    pub fn from_chat_message(msg: &ChatMessage) -> Option<Self> {
        if msg.msg_type == MessageType::System {
            Self::from_json(&msg.text).ok()
        } else {
            None
        }
    }
}

// ============================================================================
// PEER PRESENCE — Online/offline tracking for mesh peers (Block GG)
// ============================================================================

/// Peer presence status
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum PeerStatus {
    Online,
    Busy,
    InCall,
    Offline,
}

/// Tracked presence for a mesh peer
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PeerPresence {
    pub peer_key: String,
    pub short_key: String,
    pub status: PeerStatus,
    pub last_seen: String,
    pub name: Option<String>,
}

impl PeerPresence {
    pub fn new(peer_key: &str) -> Self {
        Self {
            peer_key: peer_key.to_string(),
            short_key: peer_key[..8.min(peer_key.len())].to_string(),
            status: PeerStatus::Online,
            last_seen: chrono::Utc::now().to_rfc3339(),
            name: None,
        }
    }

    pub fn update_seen(&mut self) {
        self.last_seen = chrono::Utc::now().to_rfc3339();
    }

    pub fn set_status(&mut self, status: PeerStatus) {
        self.status = status;
        self.update_seen();
    }

    pub fn is_available(&self) -> bool {
        matches!(self.status, PeerStatus::Online)
    }

    pub fn to_json_value(&self) -> serde_json::Value {
        serde_json::json!({
            "peer_key": self.peer_key,
            "short_key": self.short_key,
            "status": format!("{:?}", self.status),
            "last_seen": self.last_seen,
            "name": self.name,
        })
    }
}

// ============================================================================
// FLINT — Enhanced Chat Generation (Block FF)
// Focused Learning Intelligence for Network Threats
// Copyright 2026 Joseph Stone - All Rights Reserved
// ============================================================================

/// FLINT identity
pub const FLINT_NAME: &str = "FLINT";
pub const FLINT_VERSION: &str = "0.1.0";

/// Quality assessment for a generated response
#[derive(Debug, Clone, PartialEq)]
pub enum ResponseQuality {
    /// Good quality — send to user
    Accept { score: f32 },
    /// Poor quality — discard, use fallback
    Reject { reason: String, score: f32 },
}

/// A FLINT-generated response with metadata
#[derive(Debug, Clone)]
pub struct FlintResponse {
    /// Generated text
    pub text: String,
    /// Quality assessment
    pub quality: ResponseQuality,
    /// Tokens consumed by context (conversation + brain)
    pub context_tokens_used: usize,
    /// Tokens generated in response
    pub generation_tokens: usize,
}

/// Build a structured prompt with conversation context and optional brain knowledge.
///
/// Format:
///   <context> [brain knowledge] </context>
///   [conversation history]
///   <user> latest_message <assistant>
///
/// Context is trimmed to max_context_chars to prevent prompt overflow.
pub fn build_prompt_with_context(
    user_message: &str,
    conversation_context: Option<&str>,
    brain_context: Option<&str>,
    max_context_chars: usize,
) -> String {
    let mut prompt = String::new();

    // Brain context first (knowledge base)
    if let Some(brain) = brain_context {
        let trimmed = if brain.len() > max_context_chars / 2 {
            &brain[..max_context_chars / 2]
        } else {
            brain
        };
        prompt.push_str("<context> ");
        prompt.push_str(trimmed);
        prompt.push_str(" </context>\n");
    }

    // Conversation history (recent messages)
    if let Some(conv) = conversation_context {
        let summarized = summarize_long_context(conv, max_context_chars / 2);
        if !summarized.is_empty() {
            prompt.push_str(&summarized);
            prompt.push('\n');
        }
    }

    // Current user message + generation trigger
    prompt.push_str(&format!("<user> {} <assistant>", user_message));
    prompt
}

/// Score response quality. Returns Accept/Reject with reasoning.
///
/// Checks:
///   1. Minimum length (>= 3 chars)
///   2. Repetition detection (trigram repeated 3+ times = reject)
///   3. Combined length + diversity score (threshold: 0.2)
pub fn score_response(response: &str) -> ResponseQuality {
    let trimmed = response.trim();

    // Empty or near-empty
    if trimmed.len() < 3 {
        return ResponseQuality::Reject {
            reason: "Response too short".into(),
            score: 0.0,
        };
    }

    let words: Vec<&str> = trimmed.split_whitespace().collect();

    // Repetition detection — trigram repeated 3+ times
    if words.len() >= 9 {
        let mut trigram_counts: HashMap<String, usize> = HashMap::new();
        for window in words.windows(3) {
            let trigram = window.join(" ").to_lowercase();
            *trigram_counts.entry(trigram).or_insert(0) += 1;
        }
        let max_repeat = trigram_counts.values().max().copied().unwrap_or(0);
        if max_repeat >= 3 {
            return ResponseQuality::Reject {
                reason: format!("Excessive repetition (trigram repeated {}x)", max_repeat),
                score: 0.1,
            };
        }
    }

    // Length score (capped at 1.0 for 200+ chars)
    let length_score = (trimmed.len() as f32 / 200.0).min(1.0);

    // Diversity score — unique words / total words
    let unique: HashSet<&str> = words.iter().copied().collect();
    let diversity = if words.is_empty() { 0.0 } else {
        unique.len() as f32 / words.len() as f32
    };

    let score = (length_score * 0.4 + diversity * 0.6).min(1.0);

    if score < 0.2 {
        ResponseQuality::Reject {
            reason: "Low quality score".into(),
            score,
        }
    } else {
        ResponseQuality::Accept { score }
    }
}

/// Summarize conversation context if it exceeds max_chars.
///
/// Strategy: keep first 2 messages (topic establishment) + separator +
/// as many recent messages as fit within budget.
pub fn summarize_long_context(context: &str, max_chars: usize) -> String {
    if context.len() <= max_chars {
        return context.to_string();
    }

    let lines: Vec<&str> = context.lines().collect();
    if lines.len() <= 4 {
        return context[..max_chars].to_string();
    }

    // Keep first 2 lines (topic) + most recent lines that fit
    let header: String = lines[..2].join("\n");
    let separator = "\n[...]\n";
    let remaining = max_chars.saturating_sub(header.len() + separator.len());

    let mut tail_lines = Vec::new();
    let mut tail_len = 0;
    for line in lines.iter().rev() {
        if tail_len + line.len() + 1 > remaining {
            break;
        }
        tail_lines.push(*line);
        tail_len += line.len() + 1;
    }
    tail_lines.reverse();

    format!("{}{}{}", header, separator, tail_lines.join("\n"))
}

/// Search brain for context relevant to a query.
/// Runs the brain CLI synchronously. Returns None if brain unavailable.
// Copyright 2026 Joseph Stone — All Rights Reserved
pub fn search_brain_for_context(query: &str, _max_results: usize) -> Option<String> {
    let result = crate::brain_local::brain_context(query, "default", 2000);
    if result.starts_with("Brain not initialized") || result.starts_with("No context") {
        None
    } else {
        Some(result)
    }
}

/// Generate a complete FLINT response with context injection and quality scoring.
///
/// Pipeline:
///   1. Load tokenizer
///   2. Search brain for relevant context (optional)
///   3. Build structured prompt (brain + conversation + user message)
///   4. Generate via transformer (both writer and researcher roles)
///   5. Score response quality (accept/reject)
///
/// Both writer and researcher roles can generate. Writer uses lower temperature
/// for more focused responses. Researcher uses higher for conversational flow.
pub fn generate_flint_response(
    user_message: &str,
    conversation_context: Option<&str>,
    transformer: &Option<std::sync::Arc<std::sync::RwLock<crate::transformer_tools::TransformerState>>>,
    use_brain: bool,
) -> Option<FlintResponse> {
    let t = transformer.as_ref()?;
    let state = t.read().ok()?;

    // Load tokenizer
    let tokenizer_path = crate::paths::spf_root().join("LIVE/MODELS/tokenizer.json");
    let tokenizer = crate::tokenizer::Tokenizer::load(
        &tokenizer_path.to_string_lossy()
    ).ok()?;

    // Brain context injection (optional)
    let brain_context = if use_brain {
        search_brain_for_context(user_message, 3)
    } else {
        None
    };

    // Build structured prompt
    let prompt = build_prompt_with_context(
        user_message,
        conversation_context,
        brain_context.as_deref(),
        2000,
    );

    // Token budget: leave room for generation within model capacity
    let context_tokens = tokenizer.encode(&prompt).len();
    let max_gen_tokens = 128.min(512_usize.saturating_sub(context_tokens));

    // Temperature by role — writer more focused, researcher more creative
    let temperature = match state.role.as_str() {
        "writer" => 0.5,
        _ => 0.7,
    };

    // Generate — use training_step as seed for variety across sessions
    let result = state.model.generate_text(
        &prompt,
        max_gen_tokens,
        temperature,
        state.training_step,
        &tokenizer,
    ).ok()?;

    // Quality scoring
    let quality = score_response(&result);
    let gen_tokens = tokenizer.encode(&result).len();

    Some(FlintResponse {
        text: result,
        quality,
        context_tokens_used: context_tokens,
        generation_tokens: gen_tokens,
    })
}

// ============================================================================
// TESTS
// ============================================================================

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

    fn test_timestamp() -> String {
        "2026-02-28T12:00:00Z".to_string()
    }

    fn make_msg(from: &str, to: &str, text: &str, conv_id: &str) -> ChatMessage {
        ChatMessage {
            id: format!("msg_{}", text.len()),
            from: from.to_string(),
            to: to.to_string(),
            text: text.to_string(),
            timestamp: test_timestamp(),
            conversation_id: conv_id.to_string(),
            msg_type: MessageType::UserText,
        }
    }

    // --- Conversation tests ---

    #[test]
    fn test_conversation_add_message() {
        let mut conv = Conversation::new(
            "conv1".into(), "Test".into(), vec!["alice".into(), "bob".into()],
            test_timestamp(),
        );
        conv.add_message(make_msg("alice", "bob", "hello", "conv1"));
        conv.add_message(make_msg("bob", "alice", "hi there", "conv1"));

        assert_eq!(conv.message_count(), 2);
        assert_eq!(conv.messages[0].text, "hello");
        assert_eq!(conv.messages[1].text, "hi there");
    }

    #[test]
    fn test_conversation_context_window() {
        let mut conv = Conversation::new(
            "conv1".into(), "Test".into(), vec!["a".into()], test_timestamp(),
        );
        conv.context_window = 3;

        for i in 0..10 {
            conv.add_message(make_msg("user", "agent", &format!("msg {}", i), "conv1"));
        }

        let ctx = conv.context_messages();
        assert_eq!(ctx.len(), 3);
        assert_eq!(ctx[0].text, "msg 7");
        assert_eq!(ctx[2].text, "msg 9");
    }

    #[test]
    fn test_conversation_context_as_text() {
        let mut conv = Conversation::new(
            "c1".into(), "Test".into(), vec!["user".into()], test_timestamp(),
        );
        conv.context_window = 2;
        conv.add_message(make_msg("user", "agent", "what is SPF?", "c1"));
        conv.add_message(make_msg("agent", "user", "SPF is Smart Gateway", "c1"));

        let text = conv.context_as_text();
        assert!(text.contains("user: what is SPF?"));
        assert!(text.contains("agent: SPF is Smart Gateway"));
    }

    #[test]
    fn test_conversation_memory_trim() {
        let mut conv = Conversation::new(
            "c1".into(), "Test".into(), vec!["a".into()], test_timestamp(),
        );
        conv.max_memory_messages = 5;

        for i in 0..20 {
            conv.add_message(make_msg("user", "agent", &format!("msg {}", i), "c1"));
        }

        assert_eq!(conv.message_count(), 5);
        assert_eq!(conv.messages[0].text, "msg 15"); // oldest retained
    }

    #[test]
    fn test_conversation_participants() {
        let conv = Conversation::new(
            "c1".into(), "Test".into(),
            vec!["alice".into(), "bob".into()], test_timestamp(),
        );
        assert!(conv.has_participant("alice"));
        assert!(conv.has_participant("bob"));
        assert!(!conv.has_participant("charlie"));
    }

    // --- Chat Engine tests ---

    #[test]
    fn test_engine_receive_creates_conversation() {
        let mut engine = ChatEngine::new("local_agent".into());
        assert_eq!(engine.conversation_count(), 0);

        engine.receive_message(make_msg("alice", "local_agent", "hello", "conv1"));
        assert_eq!(engine.conversation_count(), 1);
    }

    #[test]
    fn test_engine_receive_routes_to_existing() {
        let mut engine = ChatEngine::new("agent".into());

        engine.receive_message(make_msg("alice", "agent", "hello", "room1"));
        engine.receive_message(make_msg("bob", "agent", "hi", "room1"));
        engine.receive_message(make_msg("alice", "agent", "how are you", "room1"));

        assert_eq!(engine.conversation_count(), 1);
        let conv = engine.get_conversation("room1").unwrap();
        assert_eq!(conv.message_count(), 3);
    }

    #[test]
    fn test_engine_multiple_conversations() {
        let mut engine = ChatEngine::new("agent".into());

        engine.receive_message(make_msg("alice", "agent", "hello", "conv1"));
        engine.receive_message(make_msg("bob", "agent", "hi", "conv2"));

        assert_eq!(engine.conversation_count(), 2);
        assert_eq!(engine.total_messages(), 2);
    }

    #[test]
    fn test_engine_create_message() {
        let engine = ChatEngine::new("531d83fa".into());
        let msg = engine.create_message("alice", "Hello!", "conv1", "2026-02-28T12:00:00Z");

        assert_eq!(msg.from, "531d83fa");
        assert_eq!(msg.to, "alice");
        assert_eq!(msg.text, "Hello!");
        assert_eq!(msg.conversation_id, "conv1");
        assert_eq!(msg.msg_type, MessageType::AgentResponse);
    }

    #[test]
    fn test_engine_get_context() {
        let mut engine = ChatEngine::new("agent".into());
        engine.receive_message(make_msg("user", "agent", "tell me about SPF", "c1"));

        let ctx = engine.get_context("c1").unwrap();
        assert!(ctx.contains("tell me about SPF"));

        assert!(engine.get_context("nonexistent").is_none());
    }

    #[test]
    fn test_engine_get_history() {
        let mut engine = ChatEngine::new("agent".into());
        for i in 0..10 {
            engine.receive_message(make_msg("user", "agent", &format!("msg {}", i), "c1"));
        }

        let history = engine.get_history("c1", 3);
        assert_eq!(history.len(), 3);
        assert_eq!(history[0].text, "msg 7");
    }

    #[test]
    fn test_engine_list_conversations() {
        let mut engine = ChatEngine::new("agent".into());
        engine.receive_message(make_msg("alice", "agent", "hi", "room1"));
        engine.receive_message(make_msg("bob", "agent", "hey", "room2"));

        let list = engine.list_conversations();
        assert_eq!(list.len(), 2);
        assert_eq!(list[0].id, "room1");
        assert_eq!(list[1].id, "room2");
    }

    // --- Serialization tests ---

    #[test]
    fn test_message_serialize_roundtrip() {
        let msg = make_msg("alice", "bob", "hello world", "conv1");
        let bytes = serialize_message(&msg).unwrap();
        let loaded = deserialize_message(&bytes).unwrap();
        assert_eq!(loaded.from, "alice");
        assert_eq!(loaded.text, "hello world");
        assert_eq!(loaded.conversation_id, "conv1");
    }

    #[test]
    fn test_mesh_transport_roundtrip() {
        let msg = make_msg("peer_a", "peer_b", "mesh message", "mesh_conv");
        let bytes = message_to_bytes(&msg).unwrap();
        let loaded = message_from_bytes(&bytes).unwrap();
        assert_eq!(loaded.from, "peer_a");
        assert_eq!(loaded.text, "mesh message");
    }

    #[test]
    fn test_lmdb_keys() {
        assert_eq!(message_key("conv1", "msg42"), "chat:conv:conv1:msg:msg42");
        assert_eq!(conversation_key("conv1"), "chat:conv:conv1:meta");
        assert_eq!(conversation_prefix("conv1"), "chat:conv:conv1:msg:");
        assert_eq!(chat_meta_key(), "chat:meta");
    }

    #[test]
    fn test_message_types() {
        let user_msg = make_msg("user", "agent", "hello", "c1");
        assert_eq!(user_msg.msg_type, MessageType::UserText);

        let engine = ChatEngine::new("agent".into());
        let agent_msg = engine.create_message("user", "hi", "c1", "t");
        assert_eq!(agent_msg.msg_type, MessageType::AgentResponse);
    }

    // --- Block GG: CallSignal tests ---

    #[test]
    fn test_call_signal_roundtrip() {
        let signal = CallSignal::Ring { caller: "alice".into() };
        let json = signal.to_json();
        let parsed = CallSignal::from_json(&json).unwrap();
        assert_eq!(parsed, CallSignal::Ring { caller: "alice".into() });
    }

    #[test]
    fn test_call_signal_all_variants() {
        let signals = vec![
            CallSignal::Ring { caller: "a".into() },
            CallSignal::Accept { callee: "b".into() },
            CallSignal::Reject { callee: "c".into(), reason: "busy".into() },
            CallSignal::Hangup { from: "d".into(), reason: "done".into() },
        ];
        for signal in &signals {
            let json = signal.to_json();
            assert!(!json.is_empty());
            let parsed = CallSignal::from_json(&json).unwrap();
            assert_eq!(&parsed, signal);
        }
    }

    #[test]
    fn test_call_signal_to_chat_message() {
        let signal = CallSignal::Ring { caller: "alice".into() };
        let msg = signal.to_chat_message("alice", "bob", "call_1");
        assert_eq!(msg.from, "alice");
        assert_eq!(msg.to, "bob");
        assert_eq!(msg.conversation_id, "call_1");
        assert_eq!(msg.msg_type, MessageType::System);
        assert!(msg.text.contains("Ring"));
    }

    #[test]
    fn test_call_signal_from_chat_message() {
        let signal = CallSignal::Accept { callee: "bob".into() };
        let msg = signal.to_chat_message("bob", "alice", "call_1");
        let recovered = CallSignal::from_chat_message(&msg).unwrap();
        assert_eq!(recovered, CallSignal::Accept { callee: "bob".into() });
    }

    #[test]
    fn test_call_signal_from_non_system_message() {
        let msg = make_msg("user", "agent", "hello", "c1");
        // UserText messages are not call signals
        assert!(CallSignal::from_chat_message(&msg).is_none());
    }

    #[test]
    fn test_call_signal_parse_error() {
        assert!(CallSignal::from_json("not valid json").is_err());
    }

    // --- Block GG: PeerPresence tests ---

    #[test]
    fn test_peer_presence_new() {
        let presence = PeerPresence::new("abcdef1234567890");
        assert_eq!(presence.short_key, "abcdef12");
        assert_eq!(presence.status, PeerStatus::Online);
        assert!(presence.is_available());
        assert!(presence.name.is_none());
    }

    #[test]
    fn test_peer_presence_status_changes() {
        let mut presence = PeerPresence::new("1234567890abcdef");
        assert!(presence.is_available());

        presence.set_status(PeerStatus::Busy);
        assert_eq!(presence.status, PeerStatus::Busy);
        assert!(!presence.is_available());

        presence.set_status(PeerStatus::InCall);
        assert_eq!(presence.status, PeerStatus::InCall);
        assert!(!presence.is_available());

        presence.set_status(PeerStatus::Online);
        assert!(presence.is_available());
    }

    #[test]
    fn test_peer_presence_to_json() {
        let presence = PeerPresence::new("deadbeef12345678");
        let json = presence.to_json_value();
        assert_eq!(json["short_key"], "deadbeef");
        assert_eq!(json["status"], "Online");
    }

    #[test]
    fn test_peer_status_all_variants() {
        let statuses = vec![
            PeerStatus::Online,
            PeerStatus::Busy,
            PeerStatus::InCall,
            PeerStatus::Offline,
        ];
        for status in &statuses {
            let json = serde_json::to_string(status).unwrap();
            let parsed: PeerStatus = serde_json::from_str(&json).unwrap();
            assert_eq!(&parsed, status);
        }
    }

    // --- Block FF: FLINT Enhanced Generation tests ---

    #[test]
    fn test_flint_identity() {
        assert_eq!(FLINT_NAME, "FLINT");
        assert!(!FLINT_VERSION.is_empty());
    }

    #[test]
    fn test_build_prompt_basic() {
        let prompt = build_prompt_with_context("hello", None, None, 2000);
        assert_eq!(prompt, "<user> hello <assistant>");
    }

    #[test]
    fn test_build_prompt_with_conversation() {
        let ctx = "user: what is SPF?\nagent: SPF is Smart Gateway";
        let prompt = build_prompt_with_context("tell me more", Some(ctx), None, 2000);
        assert!(prompt.contains("what is SPF?"));
        assert!(prompt.ends_with("<user> tell me more <assistant>"));
    }

    #[test]
    fn test_build_prompt_with_brain() {
        let brain = "SPF is a Rust MCP gateway with Ed25519 identity";
        let prompt = build_prompt_with_context("what is SPF?", None, Some(brain), 2000);
        assert!(prompt.contains("<context>"));
        assert!(prompt.contains("Ed25519"));
        assert!(prompt.contains("<user> what is SPF? <assistant>"));
    }

    #[test]
    fn test_build_prompt_with_both() {
        let conv = "user: hello\nagent: hi";
        let brain = "relevant knowledge";
        let prompt = build_prompt_with_context("question", Some(conv), Some(brain), 2000);
        assert!(prompt.contains("<context>"));
        assert!(prompt.contains("relevant knowledge"));
        assert!(prompt.contains("hello"));
        assert!(prompt.ends_with("<user> question <assistant>"));
    }

    #[test]
    fn test_score_response_accept() {
        let good = "SPF is a secure gateway system that routes tool calls through complexity enforcement";
        match score_response(good) {
            ResponseQuality::Accept { score } => assert!(score > 0.2),
            ResponseQuality::Reject { .. } => panic!("Expected accept"),
        }
    }

    #[test]
    fn test_score_response_reject_empty() {
        match score_response("") {
            ResponseQuality::Reject { reason, .. } => assert!(reason.contains("too short")),
            ResponseQuality::Accept { .. } => panic!("Expected reject"),
        }
    }

    #[test]
    fn test_score_response_reject_short() {
        match score_response("hi") {
            ResponseQuality::Reject { reason, .. } => assert!(reason.contains("too short")),
            ResponseQuality::Accept { .. } => panic!("Expected reject"),
        }
    }

    #[test]
    fn test_score_response_reject_repetition() {
        let repetitive = "the the the the the the the the the the the the";
        match score_response(repetitive) {
            ResponseQuality::Reject { reason, .. } => assert!(reason.contains("repetition")),
            ResponseQuality::Accept { .. } => panic!("Expected reject for repetition"),
        }
    }

    #[test]
    fn test_summarize_short_context() {
        let short = "user: hello\nagent: hi";
        assert_eq!(summarize_long_context(short, 1000), short);
    }

    #[test]
    fn test_summarize_long_context_truncates() {
        let mut long = String::new();
        for i in 0..100 {
            long.push_str(&format!("user: message number {} with some content\n", i));
        }
        let summarized = summarize_long_context(&long, 200);
        assert!(summarized.len() <= 250); // Allow line boundary overflow
        assert!(summarized.contains("message number 0")); // First preserved
        assert!(summarized.contains("[...]")); // Separator present
    }

    #[test]
    fn test_flint_response_struct() {
        let r = FlintResponse {
            text: "Hello world".into(),
            quality: ResponseQuality::Accept { score: 0.8 },
            context_tokens_used: 50,
            generation_tokens: 10,
        };
        assert_eq!(r.text, "Hello world");
        assert_eq!(r.context_tokens_used, 50);
        assert_eq!(r.generation_tokens, 10);
    }

    #[test]
    fn test_persist_conversation_returns_pairs() {
        let mut engine = ChatEngine::new("agent".into());
        engine.receive_message(make_msg("user", "agent", "hello", "c1"));
        engine.receive_message(make_msg("agent", "user", "hi there", "c1"));

        let pairs = engine.persist_conversation("c1").unwrap();
        assert_eq!(pairs.len(), 2);
        assert!(pairs[0].0.starts_with("chat:conv:c1:msg:"));
    }

    #[test]
    fn test_persist_nonexistent_conversation() {
        let engine = ChatEngine::new("agent".into());
        assert!(engine.persist_conversation("nonexistent").is_none());
    }
}