// src/modes/handlers/event.rs
use crossterm::event::Event;
use crossterm::cursor::SetCursorStyle;
use crate::tui::terminal::core::TerminalCore;
use crate::services::grpc_client::GrpcClient;
use crate::services::auth::AuthClient;
use crate::modes::common::commands::CommandHandler;
use crate::config::binds::config::Config;
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::intro::IntroState;
use crate::state::pages::admin::AdminState;
use crate::state::app::state::AppState;
use crate::state::app::buffer::{AppView, BufferState};
use crate::state::pages::canvas_state::CanvasState;
use crate::ui::handlers::rat_state::UiStateHandler;
use crate::ui::handlers::context::UiContext;
use crate::tui::functions::{intro, admin};
use crate::tui::functions::common::{login, register};
use crate::modes::{
    common::command_mode,
    canvas::{edit, read_only, common_mode},
    general::{navigation, dialog},
};
use crate::config::binds::key_sequences::KeySequenceTracker;
use crate::modes::handlers::mode_manager::{ModeManager, AppMode};
use crate::state::app::state::AppView;
use crate::tui::functions::common::form::SaveOutcome;

#[derive(Debug, Clone, PartialEq, Eq)]
pub enum EventOutcome {
    Ok(String),
    Exit(String),
    DataSaved(SaveOutcome, String),
    ButtonSelected { context: UiContext, index: usize },
}

pub struct EventHandler {
    pub command_mode: bool,
    pub command_input: String,
    pub command_message: String,
    pub is_edit_mode: bool,
    pub edit_mode_cooldown: bool,
    pub ideal_cursor_column: usize,
    pub key_sequence_tracker: KeySequenceTracker,
    pub auth_client: AuthClient,
}

impl EventHandler {
    pub async fn new() -> Result<Self, Box<dyn std::error::Error>> {
        Ok(EventHandler {
            command_mode: false,
            command_input: String::new(),
            command_message: String::new(),
            is_edit_mode: false,
            edit_mode_cooldown: false,
            ideal_cursor_column: 0,
            key_sequence_tracker: KeySequenceTracker::new(800),
            auth_client: AuthClient::new().await?,
        })
    }

    pub async fn handle_event(
        &mut self,
        event: Event,
        config: &Config,
        terminal: &mut TerminalCore,
        grpc_client: &mut GrpcClient,
        command_handler: &mut CommandHandler,
        form_state: &mut FormState,
        auth_state: &mut AuthState,
        login_state: &mut LoginState,
        register_state: &mut RegisterState,
        intro_state: &mut IntroState,
        admin_state: &mut AdminState,
        app_state: &mut AppState,
        total_count: u64,
        current_position: &mut u64,
    ) -> Result<EventOutcome, Box<dyn std::error::Error>> {
        let current_mode = ModeManager::derive_mode(app_state, self);
        app_state.update_mode(current_mode);

        // Determine the current view, including dynamic names
        let current_view = {
            let ui = &app_state.ui;
            if ui.show_intro { AppView::Intro }
            else if ui.show_login { AppView::Login }
            else if ui.show_register { AppView::Register }
            else if ui.show_admin { AppView::Admin }
            else if ui.show_form {
                let form_name = app_state.selected_profile.clone().unwrap_or_else(|| "Data Form".to_string());
                AppView::Form(form_name)
            }
            else { AppView::Scratch }
        };
        buffer_state.update_history(current_view);

        // --- DIALOG MODALITY ---
        if app_state.ui.dialog.dialog_show {
            if let Some(dialog_result) = dialog::handle_dialog_event(
                &event, config, app_state, auth_state, login_state, register_state
            ).await {
                return dialog_result;
            }
            return Ok(EventOutcome::Ok(String::new()));
        }
        // --- END DIALOG MODALITY CHECK ---

        if let Event::Key(key) = event {
            let key_code = key.code;
            let modifiers = key.modifiers;

            if UiStateHandler::toggle_sidebar(&mut app_state.ui, config, key_code, modifiers) {
                let message = format!("Sidebar {}",
                    if app_state.ui.show_sidebar { "shown" } else { "hidden" }
                );
                return Ok(EventOutcome::Ok(message));
            }
            if UiStateHandler::toggle_buffer_list(&mut app_state.ui, config, key_code, modifiers) {
                let message = format!("Buffer {}",
                    if app_state.ui.show_buffer_list { "shown" } else { "hidden" }
                );
                return Ok(EventOutcome::Ok(message));
            }
            // --- End Global UI Toggles ---

            match current_mode {
                AppMode::General => {
                    let nav_outcome = navigation::handle_navigation_event(
                        key,
                        config,
                        form_state,
                        app_state,
                        login_state,
                        register_state,
                        intro_state,
                        admin_state,
                        &mut self.command_mode,
                        &mut self.command_input,
                        &mut self.command_message,
                    ).await;
                    match nav_outcome {
                        Ok(EventOutcome::ButtonSelected { context, index }) => {
                            let mut message = String::from("Selected"); // Default message
                            match context {
                                UiContext::Intro => {
                                    intro::handle_intro_selection(app_state, index);
                                    if app_state.ui.show_admin {
                                        let profile_names = app_state.profile_tree.profiles.iter()
                                            .map(|p| p.name.clone())
                                            .collect();
                                        admin_state.set_profiles(profile_names);
                                    }
                                    message = format!("Intro Option {} selected", index);
                                }
                                UiContext::Login => {
                                    message = match index {
                                        0 => login::save(auth_state, login_state, &mut self.auth_client, app_state).await?,
                                        1 => login::back_to_main(login_state, app_state).await,
                                        _ => "Invalid Login Option".to_string(),
                                    };
                                }
                                UiContext::Register => {
                                    message = match index {
                                        0 => register::save(register_state, &mut self.auth_client, app_state).await?,
                                        1 => register::back_to_main(register_state, app_state).await,
                                        _ => "Invalid Login Option".to_string(),
                                    };
                                }
                                UiContext::Admin => {
                                    admin::handle_admin_selection(app_state, admin_state);

                                    message = format!("Admin Option {} selected", index);
                                }
                                UiContext::Dialog => {
                                    message = "Internal error: Unexpected dialog state".to_string();
                                }
                            }
                            return Ok(EventOutcome::Ok(message)); // Return Ok with message
                        }
                        other => return other, // Pass through Ok, Err, DataSaved directly
                    }
                },

                AppMode::ReadOnly => {
                    if config.is_enter_edit_mode_before(key_code, modifiers) &&
                       ModeManager::can_enter_edit_mode(current_mode) {
                        self.is_edit_mode = true;
                        self.edit_mode_cooldown = true;
                        self.command_message = "Edit mode".to_string();
                        terminal.set_cursor_style(SetCursorStyle::BlinkingBar)?;
                        return Ok(EventOutcome::Ok(self.command_message.clone()));
                    }

                    if config.is_enter_edit_mode_after(key_code, modifiers) &&
                       ModeManager::can_enter_edit_mode(current_mode) {
                        let current_input = if app_state.ui.show_login || app_state.ui.show_register{
                            login_state.get_current_input()
                        } else {
                            form_state.get_current_input()
                        };
                        let current_cursor_pos = if app_state.ui.show_login || app_state.ui.show_register{
                            login_state.current_cursor_pos()
                        } else {
                            form_state.current_cursor_pos()
                        };

                        if !current_input.is_empty() && current_cursor_pos < current_input.len() {
                             if app_state.ui.show_login || app_state.ui.show_register{
                                login_state.set_current_cursor_pos(current_cursor_pos + 1);
                                self.ideal_cursor_column = login_state.current_cursor_pos();
                            } else {
                                form_state.set_current_cursor_pos(current_cursor_pos + 1);
                                self.ideal_cursor_column = form_state.current_cursor_pos();
                            }
                        }
                        self.is_edit_mode = true;
                        self.edit_mode_cooldown = true;
                        self.command_message = "Edit mode (after cursor)".to_string();
                        terminal.set_cursor_style(SetCursorStyle::BlinkingBar)?;
                        return Ok(EventOutcome::Ok(self.command_message.clone()));
                    }

                    if let Some(action) = config.get_read_only_action_for_key(key_code, modifiers) {
                        if action == "enter_command_mode" && ModeManager::can_enter_command_mode(current_mode) {
                            self.command_mode = true;
                            self.command_input.clear();
                            self.command_message.clear();
                            return Ok(EventOutcome::Ok(String::new()));
                        }
                    }

                    if let Some(action) = config.get_action_for_key_in_mode(
                        &config.keybindings.common,
                        key_code,
                        modifiers
                    ) {
                        match action {
                            "save" | "force_quit" | "save_and_quit" | "revert" => {
                                return common_mode::handle_core_action(
                                    action,
                                    form_state,
                                    auth_state,
                                    login_state,
                                    register_state,
                                    grpc_client,
                                    &mut self.auth_client,
                                    terminal,
                                    app_state,
                                    current_position,
                                    total_count,
                                ).await;
                            },
                            _ => {}
                        }
                    }

                    let (_should_exit, message) = read_only::handle_read_only_event(
                        app_state,
                        key,
                        config,
                        form_state,
                        login_state,
                        register_state,
                        &mut self.key_sequence_tracker,
                        current_position,
                        total_count,
                        grpc_client,
                        &mut self.command_message,
                        &mut self.edit_mode_cooldown,
                        &mut self.ideal_cursor_column,
                    ).await?;
                    return Ok(EventOutcome::Ok(message));
                },

                AppMode::Edit => {
                    if config.is_exit_edit_mode(key_code, modifiers) {
                        self.is_edit_mode = false;
                        self.edit_mode_cooldown = true;

                        let has_changes = if app_state.ui.show_login || app_state.ui.show_register{
                            login_state.has_unsaved_changes()
                        } else {
                            form_state.has_unsaved_changes()
                        };

                        self.command_message = if has_changes {
                            "Exited edit mode (unsaved changes remain)".to_string()
                        } else {
                            "Read-only mode".to_string()
                        };

                        terminal.set_cursor_style(SetCursorStyle::SteadyBlock)?;

                        let current_input = if app_state.ui.show_login || app_state.ui.show_register{
                            login_state.get_current_input()
                        } else {
                            form_state.get_current_input()
                        };
                        let current_cursor_pos = if app_state.ui.show_login || app_state.ui.show_register{
                            login_state.current_cursor_pos()
                        } else {
                            form_state.current_cursor_pos()
                        };

                        if !current_input.is_empty() && current_cursor_pos >= current_input.len() {
                            let new_pos = current_input.len() - 1;
                            if app_state.ui.show_login || app_state.ui.show_register{
                                login_state.set_current_cursor_pos(new_pos);
                                self.ideal_cursor_column = login_state.current_cursor_pos();
                            } else {
                                form_state.set_current_cursor_pos(new_pos);
                                self.ideal_cursor_column = form_state.current_cursor_pos();
                            }
                        }
                        return Ok(EventOutcome::Ok(self.command_message.clone()));
                    }

                    if let Some(action) = config.get_action_for_key_in_mode(
                        &config.keybindings.common,
                        key_code,
                        modifiers
                    ) {
                        match action {
                            "save" | "force_quit" | "save_and_quit" | "revert" => {
                                return common_mode::handle_core_action(
                                    action,
                                    form_state,
                                    auth_state,
                                    login_state,
                                    register_state,
                                    grpc_client,
                                    &mut self.auth_client,
                                    terminal,
                                    app_state,
                                    current_position,
                                    total_count,
                                ).await;
                            },
                            _ => {}
                        }
                    }

                    let message = edit::handle_edit_event(
                        key,
                        config,
                        form_state,
                        login_state,
                        register_state,
                        &mut self.ideal_cursor_column,
                        &mut self.command_message,
                        current_position,
                        total_count,
                        grpc_client,
                        app_state,
                    ).await?;

                    self.key_sequence_tracker.reset();
                    return Ok(EventOutcome::Ok(message));
                },

                AppMode::Command => {
                    let outcome = command_mode::handle_command_event(
                        key,
                        config,
                        app_state,
                        login_state,
                        register_state,
                        form_state,
                        &mut self.command_input,
                        &mut self.command_message,
                        grpc_client,
                        command_handler,
                        terminal,
                        current_position,
                        total_count,
                    ).await?;

                    if let EventOutcome::Ok(msg) = &outcome {
                        if msg == "Exited command mode" {
                            self.command_mode = false;
                        }
                    }
                    return Ok(outcome);
                }
            }
        }

        self.edit_mode_cooldown = false;
        Ok(EventOutcome::Ok(self.command_message.clone()))
    }
}