// ui_channel.rs — Output routing for TUI panes
//
// All output from the agent (streaming text, tool calls, status updates)
// goes through a UiMessage enum sent over an mpsc channel. The TUI
// receives these messages and routes them to the appropriate pane.
//
// This replaces direct stdout/stderr printing throughout the codebase.
// The agent and API client never touch the terminal directly — they
// just send messages that the TUI renders where appropriate.
//
// The channel also fans out to a broadcast channel so the observation
// socket (observe.rs) can subscribe without touching the main path.

use std::sync::{Arc, RwLock};
use tokio::sync::{broadcast, mpsc};

/// Shared, live context state — agent writes, TUI reads for the debug screen.
pub type SharedContextState = Arc<RwLock<Vec<ContextSection>>>;

/// Create a new shared context state.
pub fn shared_context_state() -> SharedContextState {
    Arc::new(RwLock::new(Vec::new()))
}

/// Which pane streaming text should go to.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum StreamTarget {
    /// User-initiated turn — text goes to conversation pane.
    Conversation,
    /// DMN-initiated turn — text goes to autonomous pane.
    Autonomous,
}

/// Status info for the bottom status bar.
#[derive(Debug, Clone)]
#[allow(dead_code)]
pub struct StatusInfo {
    pub dmn_state: String,
    pub dmn_turns: u32,
    pub dmn_max_turns: u32,
    pub prompt_tokens: u32,
    pub completion_tokens: u32,
    pub model: String,
    /// Number of tool calls dispatched in the current turn.
    pub turn_tools: u32,
    /// Context window budget breakdown (e.g. "id:8% mem:25% jnl:30% conv:37%").
    pub context_budget: String,
}

/// A section of the context window, possibly with children.
#[derive(Debug, Clone)]
pub struct ContextSection {
    pub name: String,
    pub tokens: usize,
    pub content: String,
    pub children: Vec<ContextSection>,
}

/// Context loading details for the debug screen.
#[derive(Debug, Clone)]
pub struct ContextInfo {
    pub model: String,
    pub available_models: Vec<String>,
    pub prompt_file: String,
    pub backend: String,
    #[allow(dead_code)]
    pub instruction_files: Vec<(String, usize)>,
    #[allow(dead_code)]
    pub memory_files: Vec<(String, usize)>,
    pub system_prompt_chars: usize,
    pub context_message_chars: usize,
}

/// Messages sent from agent/API to the TUI for rendering.
#[derive(Debug, Clone)]
#[allow(dead_code)]
pub enum UiMessage {
    /// Streaming text delta — routed to conversation or autonomous pane
    /// based on the current StreamTarget.
    TextDelta(String, StreamTarget),

    /// User's input echoed to conversation pane.
    UserInput(String),

    /// Tool call header: [tool_name] with args summary.
    ToolCall {
        name: String,
        args_summary: String,
    },

    /// Full tool result — goes to tools pane.
    ToolResult {
        name: String,
        result: String,
    },

    /// DMN state annotation: [dmn: foraging (3/20)].
    DmnAnnotation(String),

    /// Status bar update.
    StatusUpdate(StatusInfo),

    /// Live activity indicator for the status bar — shows what the
    /// agent is doing right now ("thinking...", "calling: bash", etc).
    /// Empty string clears the indicator.
    Activity(String),

    /// Reasoning/thinking tokens from the model (internal monologue).
    /// Routed to the autonomous pane so the user can peek at what
    /// the model is thinking about during long tool chains.
    Reasoning(String),

    /// A tool call started — shown as a live overlay above the status bar.
    ToolStarted { id: String, name: String, detail: String },

    /// A tool call finished — removes it from the live overlay.
    ToolFinished { id: String },

    /// Debug message (only shown when POC_DEBUG is set).
    Debug(String),

    /// Informational message — goes to conversation pane (command output, etc).
    Info(String),

    /// Context loading details — stored for the debug screen (Ctrl+D).
    ContextInfoUpdate(ContextInfo),

    /// Agent cycle state update — refreshes the F2 agents screen.
    AgentUpdate(Vec<crate::subconscious::hook::AgentSnapshot>),
}

/// Sender that fans out to both the TUI (mpsc) and observers (broadcast).
#[derive(Clone)]
pub struct UiSender {
    tui: mpsc::UnboundedSender<UiMessage>,
    observe: broadcast::Sender<UiMessage>,
}

impl UiSender {
    pub fn send(&self, msg: UiMessage) -> Result<(), mpsc::error::SendError<UiMessage>> {
        // Broadcast to observers (ignore errors — no subscribers is fine)
        let _ = self.observe.send(msg.clone());
        self.tui.send(msg)
    }

    /// Subscribe to the broadcast side (for the observation socket).
    pub fn subscribe(&self) -> broadcast::Receiver<UiMessage> {
        self.observe.subscribe()
    }
}

/// Convenience type for the receiving half.
pub type UiReceiver = mpsc::UnboundedReceiver<UiMessage>;

/// Create a new UI channel pair.
pub fn channel() -> (UiSender, UiReceiver) {
    let (tui_tx, tui_rx) = mpsc::unbounded_channel();
    let (observe_tx, _) = broadcast::channel(1024);
    (UiSender { tui: tui_tx, observe: observe_tx }, tui_rx)
}