//! Miscellaneous state: overlay enum, misc state bag, editor state.

use std::path::PathBuf;
use zesdex_infrastructure::Toast;

/// Which modal overlay, if any, is currently shown over the main TUI view.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Overlay {
    /// No overlay; the main chat view is shown.
    None,
    /// Key bindings help screen.
    Help,
    /// Settings/configuration panel.
    Settings,
    /// Background bash job viewer.
    Bash,
    /// "Are you sure you want to quit?" confirmation.
    QuitConfirm,
    /// Raw key-code input capture (for binding custom keys).
    KeyInput,
    /// Inline editor (opened via `/edit`).
    Editor,
    /// Reasoning effort level selector.
    Effort,
    /// MCP server management panel.
    Mcp,
    /// Task list overlay.
    Todo,
    /// Project plan overlay.
    Plan,
    /// Session rewind / history scrubber.
    Rewind,
    /// Learning / lesson management panel.
    Learning,
    /// Token usage statistics panel.
    Usage,
    /// Generic loading spinner overlay.
    Loading,
    /// Model selector dropdown.
    ModelSelector,
    /// "Clear conversation?" confirmation.
    ClearConfirm,
    /// Git diff preview overlay.
    Diff,
}

impl Overlay {
    /// Human-readable name for this overlay variant.
    pub fn as_str(&self) -> &'static str {
        match self {
            Overlay::None => "none",
            Overlay::Help => "help",
            Overlay::Settings => "settings",
            Overlay::Bash => "bash",
            Overlay::QuitConfirm => "quit_confirm",
            Overlay::KeyInput => "key_input",
            Overlay::Editor => "editor",
            Overlay::Effort => "effort",
            Overlay::Mcp => "mcp",
            Overlay::Todo => "todo",
            Overlay::Plan => "plan",
            Overlay::Rewind => "rewind",
            Overlay::Learning => "learning",
            Overlay::Usage => "usage",
            Overlay::Loading => "loading",
            Overlay::ModelSelector => "model_selector",
            Overlay::ClearConfirm => "clear_confirm",
            Overlay::Diff => "diff",
        }
    }

    /// Whether any overlay (i.e. anything other than `None`) is active.
    pub fn is_active(self) -> bool {
        !matches!(self, Overlay::None)
    }
}

impl std::fmt::Display for Overlay {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.write_str(self.as_str())
    }
}

/// Simple inline editor state for the TUI.
#[derive(Debug, Clone)]
pub struct EditorState {
    /// Path to the file being edited.
    pub path: PathBuf,
    /// Current buffer content.
    pub content: String,
    /// Cursor position (byte offset).
    pub cursor: usize,
}

impl EditorState {
    /// Create a new editor state for the given path.
    pub fn new(path: PathBuf, content: String) -> Self {
        let cursor = content.len();
        EditorState {
            path,
            content,
            cursor,
        }
    }

    /// Return the full buffer content.
    pub fn as_string(&self) -> String {
        self.content.clone()
    }

    /// Delete one character to the left of the cursor.
    pub fn delete_left(&mut self) {
        if self.cursor > 0 {
            self.cursor -= 1;
            self.content.remove(self.cursor);
        }
    }
}

/// The "miscellaneous" slice of app state.
#[derive(Debug, Clone)]
pub struct MiscState {
    /// Currently active modal overlay (None = main chat view).
    pub overlay: Overlay,
    /// Active toast notifications.
    pub toasts: Vec<Toast>,
    /// Timestamp (ms) of the last staleness sweep for lesson cache.
    pub last_staleness_sweep_ms: i64,
    /// Whether the agent is currently "thinking".
    pub thinking: bool,
    /// Current LLM reasoning effort level (1-5).
    pub effort_level: usize,
    /// Currently focused index in list-type overlays.
    pub selected_index: usize,
    /// Optional inline editor state.
    pub editor: Option<EditorState>,
    /// Whether the API connection is established.
    pub api_connected: bool,
    /// Monotonically increasing tick count, incremented each render frame.
    pub tick_count: u64,
    /// Cached content of the TODO file.
    pub todo_content: String,
    /// Cached content of the PLAN file.
    pub plan_content: String,
    /// Whether a lesson background task is currently running.
    pub lesson_running: bool,
    /// Text waiting to be written to the system clipboard.
    pub pending_clipboard_copy: Option<String>,
    /// Cached git diff content for the preview overlay.
    pub diff_content: String,
    /// Scroll offset for the diff overlay.
    pub diff_scroll: usize,
}

impl MiscState {
    /// Create a fresh `MiscState` with no overlay, no toasts.
    pub fn new() -> Self {
        MiscState {
            overlay: Overlay::None,
            toasts: Vec::new(),
            last_staleness_sweep_ms: 0,
            thinking: false,
            effort_level: 1,
            selected_index: 0,
            editor: None,
            api_connected: false,
            tick_count: 0,
            todo_content: String::new(),
            plan_content: String::new(),
            lesson_running: false,
            pending_clipboard_copy: None,
            diff_content: String::new(),
            diff_scroll: 0,
        }
    }

    /// Append a toast notification to the active list.
    pub fn push_toast(&mut self, toast: Toast) {
        self.toasts.push(toast);
    }

    /// Remove all toasts whose lifetime has expired at `now_ms`.
    pub fn drain_expired_toasts(&mut self, now_ms: i64) {
        self.toasts.retain(|t| !t.expired(now_ms));
    }
}

impl Default for MiscState {
    fn default() -> Self {
        Self::new()
    }
}