// src/ui/handlers/ui.rs

use crate::config::binds::config::Config;
use crate::config::colors::themes::Theme;
use crate::services::grpc_client::GrpcClient;
use crate::services::ui_service::UiService;
use crate::config::storage::storage::load_auth_data;
use crate::modes::common::commands::CommandHandler;
use crate::modes::handlers::event::{EventHandler, EventOutcome};
use crate::modes::handlers::mode_manager::{AppMode, ModeManager};
use crate::state::pages::canvas_state::CanvasState;
use crate::state::pages::form::FormState;
use crate::state::pages::auth::AuthState;
use crate::state::pages::auth::LoginState;
use crate::state::pages::auth::RegisterState;
use crate::state::pages::admin::AdminState;
use crate::state::pages::admin::AdminFocus;
use crate::state::pages::intro::IntroState;
use crate::state::app::buffer::BufferState;
use crate::state::app::buffer::AppView;
use crate::state::app::state::AppState;
use crate::tui::terminal::{EventReader, TerminalCore};
use crate::ui::handlers::render::render_ui;
use crate::tui::functions::common::login::LoginResult;
use crate::tui::functions::common::register::RegisterResult;
use crate::tui::functions::common::add_table::handle_save_table_action;
use crate::functions::modes::navigation::add_table_nav::SaveTableResultSender;
use crate::ui::handlers::context::{DialogPurpose, UiContext};
use crate::tui::functions::common::login;
use crate::tui::functions::common::register;
use std::time::Instant;
use anyhow::{Context, Result};
use crossterm::cursor::SetCursorStyle;
use crossterm::event as crossterm_event;
use tracing::{error, info};
use tokio::sync::mpsc;


pub async fn run_ui() -> Result<()> {
    let config = Config::load().context("Failed to load configuration")?;
    let theme = Theme::from_str(&config.colors.theme);
    let mut terminal = TerminalCore::new().context("Failed to initialize terminal")?;
    let mut grpc_client = GrpcClient::new().await?;
    let mut command_handler = CommandHandler::new();

    // --- Channel for Login Results ---
    let (login_result_sender, mut login_result_receiver) =
        mpsc::channel::<LoginResult>(1);
    let (register_result_sender, mut register_result_receiver) =
        mpsc::channel::<RegisterResult>(1);
    let (save_table_result_sender, mut save_table_result_receiver) =
        mpsc::channel::<Result<String>>(1);
    let (save_logic_result_sender, mut save_logic_result_receiver) =
        mpsc::channel::<Result<String>>(1);

    let mut event_handler = EventHandler::new(
        login_result_sender.clone(),
        register_result_sender.clone(),
        save_table_result_sender.clone(),
        save_logic_result_sender.clone(),
    ).await.context("Failed to create event handler")?;
    let event_reader = EventReader::new();

    let mut auth_state = AuthState::default();
    let mut login_state = LoginState::default();
    let mut register_state = RegisterState::default();
    let mut intro_state = IntroState::default();
    let mut admin_state = AdminState::default();
    let mut buffer_state = BufferState::default();
    let mut app_state = AppState::new().context("Failed to create initial app state")?;

    // --- DATA: Load auth data from file at startup ---
    let mut auto_logged_in = false;
    match load_auth_data() {
        Ok(Some(stored_data)) => {
            // TODO: Optionally validate token with server here
            // For now, assume valid if successfully loaded
            auth_state.auth_token = Some(stored_data.access_token);
            auth_state.user_id = Some(stored_data.user_id);
            auth_state.role = Some(stored_data.role);
            auth_state.decoded_username = Some(stored_data.username);
            auto_logged_in = true;
            info!("Auth data loaded from file. User is auto-logged in.");
        }
        Ok(None) => {
            info!("No stored auth data found. User will see intro/login.");
        }
        Err(e) => {
            error!("Failed to load auth data: {}", e);
        }
    }
    // --- END DATA ---

    // Initialize app state with profile tree and table structure
    let column_names =
        UiService::initialize_app_state(&mut grpc_client, &mut app_state)
            .await.context("Failed to initialize app state from UI service")?;
    let mut form_state = FormState::new(column_names);

    // Fetch the total count of Adresar entries
    UiService::initialize_adresar_count(&mut grpc_client, &mut app_state).await?;
    form_state.reset_to_empty();

    // --- DATA2: Adjust initial view based on auth status ---
    if auto_logged_in {
        // User is auto-logged in, go to main app view
        buffer_state.history = vec![AppView::Form("Adresar".to_string())];
        buffer_state.active_index = 0;
        info!("Initial view set to Form due to auto-login.");
    }
    // If not auto-logged in, BufferState default (Intro) will be used
    // --- END DATA2 ---

    // --- FPS Calculation State ---
    let mut last_frame_time = Instant::now();
    let mut current_fps = 0.0;
    let mut needs_redraw = true;

    loop {
        // --- Synchronize UI View from Active Buffer ---
        if let Some(active_view) = buffer_state.get_active_view() {
            // Reset all flags first
            app_state.ui.show_intro = false;
            app_state.ui.show_login = false;
            app_state.ui.show_register = false;
            app_state.ui.show_admin = false;
            app_state.ui.show_add_table = false;
            app_state.ui.show_add_logic = false;
            app_state.ui.show_form = false;
            match active_view {
                AppView::Intro => app_state.ui.show_intro = true,
                AppView::Login => app_state.ui.show_login = true,
                AppView::Register => app_state.ui.show_register = true,
                AppView::Admin => {
                    info!("Active view is Admin, refreshing profile tree...");
                    match grpc_client.get_profile_tree().await {
                        Ok(refreshed_tree) => {
                            app_state.profile_tree = refreshed_tree;
                        }
                        Err(e) => {
                            error!("Failed to refresh profile tree for Admin panel: {}", e);
                            event_handler.command_message = format!("Error refreshing admin data: {}", e);
                        }
                    }
                    app_state.ui.show_admin = true; // <<< RESTORE THIS
                    let profile_names = app_state.profile_tree.profiles.iter() // <<< RESTORE THIS
                        .map(|p| p.name.clone())                              // <<< RESTORE THIS
                        .collect();                                             // <<< RESTORE THIS
                    admin_state.set_profiles(profile_names);

                    // Only reset to ProfilesPane if not already in a specific admin sub-focus
                    if admin_state.current_focus == AdminFocus::default() || 
                       !matches!(admin_state.current_focus, 
                                AdminFocus::InsideProfilesList |
                                AdminFocus::Tables | AdminFocus::InsideTablesList |
                                AdminFocus::Button1 | AdminFocus::Button2 | AdminFocus::Button3) {
                         admin_state.current_focus = AdminFocus::ProfilesPane;
                    }
                    // Pre-select first profile item for visual consistency, but '>' won't show until 'select'
                    if admin_state.profile_list_state.selected().is_none() && !app_state.profile_tree.profiles.is_empty() {
                        admin_state.profile_list_state.select(Some(0));
                    }
                }
                AppView::AddTable => app_state.ui.show_add_table = true,
                AppView::AddLogic => app_state.ui.show_add_logic = true,
                AppView::Form(_) => app_state.ui.show_form = true,
                AppView::Scratch => {} // Or show a scratchpad component
            }
        }
        // --- End Synchronization ---

        // --- 3. Draw UI ---
        // Draw the current state *first*. This ensures the loading dialog
        // set in the *previous* iteration gets rendered before the pending
        // action check below.
        if needs_redraw { 
            terminal.draw(|f| {
                render_ui(
                    f,
                    &mut form_state,
                    &mut auth_state,
                    &login_state,
                    &register_state,
                    &intro_state,
                    &mut admin_state,
                    &buffer_state,
                    &theme,
                    event_handler.is_edit_mode, // Use event_handler's state
                    &event_handler.highlight_state,
                    app_state.total_count,
                    app_state.current_position,
                    &app_state.current_dir,
                    &event_handler.command_input,
                    event_handler.command_mode,
                    &event_handler.command_message,
                    current_fps,
                    &app_state,
                );
            }).context("Terminal draw call failed")?;
            needs_redraw = false;
        }

        // --- Cursor Visibility Logic ---
        // (Keep existing cursor logic here - depends on state drawn above)
        let current_mode = ModeManager::derive_mode(&app_state, &event_handler, &admin_state);
        match current_mode {
            AppMode::Edit => { terminal.show_cursor()?; }
            AppMode::Highlight => { terminal.set_cursor_style(SetCursorStyle::SteadyBlock)?; terminal.show_cursor()?; }
            AppMode::ReadOnly => {
                if !app_state.ui.focus_outside_canvas { terminal.set_cursor_style(SetCursorStyle::SteadyBlock)?; }
                else { terminal.set_cursor_style(SetCursorStyle::SteadyUnderScore)?; }
                terminal.show_cursor().context("Failed to show cursor in ReadOnly mode")?;
            }
            AppMode::General => {
                if app_state.ui.focus_outside_canvas { terminal.set_cursor_style(SetCursorStyle::SteadyUnderScore)?; terminal.show_cursor()?; }
                else { terminal.hide_cursor()?; }
            }
            AppMode::Command => { terminal.set_cursor_style(SetCursorStyle::SteadyUnderScore)?; terminal.show_cursor().context("Failed to show cursor in Command mode")?; }
        }
        // --- End Cursor Visibility Logic ---

        let total_count = app_state.total_count;
        let mut current_position = app_state.current_position;
        let position_before_event = current_position;
        // --- Determine if redraw is needed based on active login ---
        // Always redraw if the loading dialog is currently showing.
        if app_state.ui.dialog.is_loading {
            needs_redraw = true;
        }

        // --- 1. Handle Terminal Events ---
        let mut event_outcome_result = Ok(EventOutcome::Ok(String::new()));
        let mut event_processed = false;
        // Poll for events *after* drawing and checking pending actions
        if crossterm_event::poll(std::time::Duration::from_millis(1))? {
            let event = event_reader.read_event().context("Failed to read terminal event")?;
            event_processed = true; // Mark that we received and will process an event
            event_outcome_result = event_handler.handle_event(
                event,
                &config,
                &mut terminal,
                &mut grpc_client,
                &mut command_handler,
                &mut form_state,
                &mut auth_state,
                &mut login_state,
                &mut register_state,
                &mut intro_state,
                &mut admin_state,
                &mut buffer_state,
                &mut app_state,
                total_count,
                &mut current_position,
            ).await;
        }

        if event_processed {
            needs_redraw = true;
        }

        // Update position based on handler's modification
        // This happens *after* the event is handled
        app_state.current_position = current_position;

        // --- Check for Login Results from Channel ---
        match login_result_receiver.try_recv() {
            Ok(result) => {
                if login::handle_login_result(result, &mut app_state, &mut auth_state, &mut login_state) {
                    needs_redraw = true;
                }
            }
            Err(mpsc::error::TryRecvError::Empty) => { /* No message waiting */ }
            Err(mpsc::error::TryRecvError::Disconnected) => {
                error!("Login result channel disconnected unexpectedly.");
                // Optionally show an error dialog here
            }
        }

        // --- Check for Register Results from Channel ---
        match register_result_receiver.try_recv() {
            Ok(result) => {
                if register::handle_registration_result(result, &mut app_state, &mut register_state) {
                    needs_redraw = true;
                }
            }
            Err(mpsc::error::TryRecvError::Empty) => { /* No message waiting */ }
            Err(mpsc::error::TryRecvError::Disconnected) => {
                error!("Register result channel disconnected unexpectedly.");
            }
        }
        // --- Check for Save Table Results ---
        match save_table_result_receiver.try_recv() {
            Ok(result) => {
                app_state.hide_dialog(); // Hide loading indicator
                match result {
                    Ok(ref success_message) => {
                        app_state.show_dialog(
                            "Save Successful",
                            success_message,
                            vec!["OK".to_string()],
                            DialogPurpose::SaveTableSuccess,
                        );
                        admin_state.add_table_state.has_unsaved_changes = false;
                    }
                    Err(e) => {
                        event_handler.command_message = format!("Save failed: {}", e);
                        // Optionally show an error dialog instead of just command message
                    }
                }
                needs_redraw = true;
            }
            Err(mpsc::error::TryRecvError::Empty) => {} // No message
            Err(mpsc::error::TryRecvError::Disconnected) => {
                error!("Save table result channel disconnected unexpectedly.");
            }
        }

        // --- Centralized Consequence Handling ---
        let mut should_exit = false;
        match event_outcome_result {
            Ok(outcome) => match outcome {
                EventOutcome::Ok(message) => {
                    if !message.is_empty() {
                        // Update command message only if event handling produced one
                        // Avoid overwriting messages potentially set by pending actions
                        // event_handler.command_message = message;
                    }
                }
                EventOutcome::Exit(message) => {
                    event_handler.command_message = message;
                    should_exit = true;
                }
                EventOutcome::DataSaved(save_outcome, message) => {
                    event_handler.command_message = message; // Show save status
                    if let Err(e) = UiService::handle_save_outcome(
                        save_outcome,
                        &mut grpc_client,
                        &mut app_state,
                        &mut form_state,
                    )
                    .await
                    {
                        event_handler.command_message =
                            format!("Error handling save outcome: {}", e);
                    }
                }
                EventOutcome::ButtonSelected { context: _, index: _ } => {
                    // This case should ideally be fully handled within handle_event
                    // If initiate_login was called, it returned early.
                    // If not, the message was set and returned via Ok(message).
                    // Log if necessary, but likely no action needed here.
                    // log::warn!("ButtonSelected outcome reached main loop unexpectedly.");
                }
            },
            Err(e) => {
                event_handler.command_message = format!("Error: {}", e);
            }
        } // --- End Consequence Handling ---

        // --- Position Change Handling (after outcome processing and pending actions) ---
        let position_changed = app_state.current_position != position_before_event;
        let current_total_count = app_state.total_count;
        let mut position_logic_needs_redraw = false;
        if app_state.ui.show_form {
            if position_changed && !event_handler.is_edit_mode {
                let current_input = form_state.get_current_input();
                let max_cursor_pos = if !current_input.is_empty() {
                    current_input.len() - 1 // Limit to last character in readonly mode
                } else {
                    0
                };
                form_state.current_cursor_pos =
                    event_handler.ideal_cursor_column.min(max_cursor_pos);
                position_logic_needs_redraw = true;

                // Ensure position never exceeds total_count + 1
                if app_state.current_position > current_total_count + 1 {
                    app_state.current_position = current_total_count + 1;
                }
                if app_state.current_position > current_total_count {
                    // New entry - reset form
                    form_state.reset_to_empty();
                    form_state.current_field = 0;
                } else if app_state.current_position >= 1
                    && app_state.current_position <= current_total_count
                {
                    // Existing entry - load data
                    let current_position_to_load = app_state.current_position; // Use a copy
                    let load_message = UiService::load_adresar_by_position(
                        &mut grpc_client,
                        &mut app_state, // Pass app_state mutably if needed by the service
                        &mut form_state,
                        current_position_to_load,
                    )
                    .await.with_context(|| format!("Failed to load adresar by position: {}", current_position_to_load))?;

                    let current_input = form_state.get_current_input();
                    let max_cursor_pos = if !event_handler.is_edit_mode
                        && !current_input.is_empty()
                    {
                        current_input.len() - 1 // In readonly mode, limit to last character
                    } else {
                        current_input.len()
                    };
                    form_state.current_cursor_pos = event_handler
                        .ideal_cursor_column
                        .min(max_cursor_pos);
                    // Don't overwrite message from handle_event if load_message is simple success
                    if !load_message.starts_with("Loaded entry")
                        || event_handler.command_message.is_empty()
                    {
                        event_handler.command_message = load_message;
                    }
                } else {
                    // Invalid position (e.g., 0) - reset to first entry or new entry mode
                    app_state.current_position =
                        1.min(current_total_count + 1); // Go to 1 or new entry if empty
                    if app_state.current_position > total_count {
                        form_state.reset_to_empty();
                        form_state.current_field = 0;
                    }
                }
            } else if !position_changed && !event_handler.is_edit_mode {
                // If position didn't change but we are in read-only, just adjust cursor
                let current_input = form_state.get_current_input();
                let max_cursor_pos = if !current_input.is_empty() {
                    current_input.len() - 1
                } else {
                    0
                };
                form_state.current_cursor_pos =
                    event_handler.ideal_cursor_column.min(max_cursor_pos);
            }
        } else if app_state.ui.show_register {
             if !event_handler.is_edit_mode {
                let current_input = register_state.get_current_input();
                let max_cursor_pos = if !current_input.is_empty() {
                    current_input.len() - 1
                } else {
                    0
                };
                register_state.current_cursor_pos = event_handler.ideal_cursor_column.min(max_cursor_pos);
            }
        } else if app_state.ui.show_login {
             if !event_handler.is_edit_mode {
                let current_input = login_state.get_current_input();
                let max_cursor_pos = if !current_input.is_empty() {
                    current_input.len() - 1
                } else {
                    0
                };
                login_state.current_cursor_pos = event_handler.ideal_cursor_column.min(max_cursor_pos);
            }
        }
        if position_logic_needs_redraw {
            needs_redraw = true;
        }
        // --- End Position Change Handling ---

        // Check exit condition *after* all processing for the iteration
        if should_exit {
            return Ok(());
        }

        // --- FPS Calculation ---
        let now = Instant::now();
        let frame_duration = now.duration_since(last_frame_time);
        last_frame_time = now;
        if frame_duration.as_secs_f64() > 1e-6 {
            current_fps = 1.0 / frame_duration.as_secs_f64();
        }
    } // End main loop
}