// Copyright 2023 The Grim Developers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::sync::atomic::{AtomicBool, Ordering};

use egui::os::OperatingSystem;
use egui::RichText;
use lazy_static::lazy_static;

use crate::gui::Colors;
use crate::gui::platform::PlatformCallbacks;
use crate::gui::views::{WalletsContent, Modal, ModalContainer, Network, View};
use crate::node::Node;

lazy_static! {
    /// Global state to check if [`Network`] panel is open.
    static ref NETWORK_PANEL_OPEN: AtomicBool = AtomicBool::new(false);
}

/// Contains main ui content, handles side panel state.
pub struct Root {
    /// Side panel [`Network`] content.
    network: Network,
    /// Central panel [`WalletsContent`] content.
    wallets: WalletsContent,

    /// Check if app exit is allowed on close event of [`eframe::App`] implementation.
    pub(crate) exit_allowed: bool,

    /// Flag to show exit progress at [`Modal`].
    show_exit_progress: bool,

    /// List of allowed [`Modal`] ids for this [`ModalContainer`].
    allowed_modal_ids: Vec<&'static str>
}

impl Default for Root {
    fn default() -> Self {
        // Exit from eframe only for non-mobile platforms.
        let os = OperatingSystem::from_target_os();
        let exit_allowed = os == OperatingSystem::Android || os == OperatingSystem::IOS;
        Self {
            network: Network::default(),
            wallets: WalletsContent::default(),
            exit_allowed,
            show_exit_progress: false,
            allowed_modal_ids: vec![
                Self::EXIT_MODAL_ID
            ],
        }
    }
}

impl ModalContainer for Root {
    fn modal_ids(&self) -> &Vec<&'static str> {
        &self.allowed_modal_ids
    }
}

impl Root {
    /// Identifier for exit confirmation [`Modal`].
    pub const EXIT_MODAL_ID: &'static str = "exit_confirmation";

    /// Default width of side panel at application UI.
    pub const SIDE_PANEL_MIN_WIDTH: f32 = 400.0;

    pub fn ui(&mut self, ui: &mut egui::Ui, frame: &mut eframe::Frame, cb: &dyn PlatformCallbacks) {
        // Show opened exit confirmation modal content.
        if self.can_draw_modal() {
            self.exit_modal_content(ui, frame, cb);
        }

        let (is_panel_open, panel_width) = Self::network_panel_state_width(frame);
        // Show network content.
        egui::SidePanel::left("network_panel")
            .resizable(false)
            .exact_width(panel_width)
            .frame(egui::Frame {
                fill: Colors::WHITE,
                ..Default::default()
            })
            .show_animated_inside(ui, is_panel_open, |ui| {
                self.network.ui(ui, frame, cb);
            });

        // Show wallets content.
        egui::CentralPanel::default()
            .frame(egui::Frame {
                fill: Colors::FILL_DARK,
                ..Default::default()
            })
            .show_inside(ui, |ui| {
                self.wallets.ui(ui, frame, cb);
            });
    }

    /// Get [`Network`] panel state and width.
    fn network_panel_state_width(frame: &mut eframe::Frame) -> (bool, f32) {
        let dual_panel_mode = Self::is_dual_panel_mode(frame);
        let is_panel_open = dual_panel_mode || Self::is_network_panel_open();
        let panel_width = if dual_panel_mode {
            Self::SIDE_PANEL_MIN_WIDTH + View::get_left_inset()
        } else {
            frame.info().window_info.size.x
        };
        (is_panel_open, panel_width)
    }

    /// Check if ui can show [`Network`] and [`WalletsContent`] at same time.
    pub fn is_dual_panel_mode(frame: &mut eframe::Frame) -> bool {
        let w = frame.info().window_info.size.x;
        let h = frame.info().window_info.size.y;
        // Screen is wide if width is greater than height or just 20% smaller.
        let is_wide_screen = w > h || w + (w * 0.2) >= h;
        // Dual panel mode is available when window is wide and its width is at least 2 times
        // greater than minimal width of the side panel plus display insets from both sides.
        let side_insets = View::get_left_inset() + View::get_right_inset();
        is_wide_screen && w >= (Self::SIDE_PANEL_MIN_WIDTH * 2.0) + side_insets
    }

    /// Toggle [`Network`] panel state.
    pub fn toggle_network_panel() {
        let is_open = NETWORK_PANEL_OPEN.load(Ordering::Relaxed);
        NETWORK_PANEL_OPEN.store(!is_open, Ordering::Relaxed);
    }

    /// Check if [`Network`] panel is open.
    pub fn is_network_panel_open() -> bool {
        NETWORK_PANEL_OPEN.load(Ordering::Relaxed)
    }

    /// Show exit confirmation modal.
    pub fn show_exit_modal() {
        Modal::new(Self::EXIT_MODAL_ID)
            .title(t!("modal.confirmation"))
            .show();
    }

    /// Draw exit confirmation modal content.
    fn exit_modal_content(&mut self,
                          ui: &mut egui::Ui,
                          frame: &mut eframe::Frame,
                          cb: &dyn PlatformCallbacks) {
        Modal::ui(ui, |ui, modal| {
            if self.show_exit_progress {
                if !Node::is_running() {
                    self.exit(frame, cb);
                    modal.close();
                }
                ui.add_space(16.0);
                ui.vertical_centered(|ui| {
                    View::small_loading_spinner(ui);
                    ui.add_space(12.0);
                    ui.label(RichText::new(t!("sync_status.shutdown"))
                        .size(17.0)
                        .color(Colors::TEXT));
                });
                ui.add_space(10.0);
            } else {
                ui.add_space(8.0);
                ui.vertical_centered(|ui| {
                    ui.label(RichText::new(t!("modal_exit.description"))
                        .size(17.0)
                        .color(Colors::TEXT));
                });
                ui.add_space(10.0);

                // Show modal buttons.
                ui.scope(|ui| {
                    // Setup spacing between buttons.
                    ui.spacing_mut().item_spacing = egui::Vec2::new(6.0, 0.0);

                    ui.columns(2, |columns| {
                        columns[0].vertical_centered_justified(|ui| {
                            View::button(ui, t!("modal_exit.exit"), Colors::WHITE, || {
                                if !Node::is_running() {
                                    self.exit(frame, cb);
                                    modal.close();
                                } else {
                                    Node::stop(true);
                                    modal.disable_closing();
                                    self.show_exit_progress = true;
                                }
                            });
                        });
                        columns[1].vertical_centered_justified(|ui| {
                            View::button(ui, t!("modal.cancel"), Colors::WHITE, || {
                                modal.close();
                            });
                        });
                    });
                    ui.add_space(6.0);
                });
            }
        });
    }

    /// Platform-specific exit from the application.
    fn exit(&mut self, frame: &mut eframe::Frame, cb: &dyn PlatformCallbacks) {
        match OperatingSystem::from_target_os() {
            OperatingSystem::Android => {
                cb.exit();
            }
            OperatingSystem::IOS => {
                //TODO: exit on iOS.
            }
            OperatingSystem::Nix | OperatingSystem::Mac | OperatingSystem::Windows => {
                self.exit_allowed = true;
                frame.close();
            }
            OperatingSystem::Unknown => {}
        }
    }

    /// Handle Back key event.
    pub fn on_back(&mut self) {
        if Modal::on_back() {
            if self.wallets.on_back() {
                Self::show_exit_modal()
            }
        }
    }
}