/*
 * Copyright © Canonical Ltd.
 *
 * This program is free software: you can redistribute it and/or modify
 * under the terms of the GNU General Public License version 2 or 3 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <miral/locate_pointer.h>
#include <miral/minimal_window_manager.h>
#include "tiling_window_manager.h"
#include "floating_window_manager.h"
#include "wallpaper_config.h"
#include "spinner/splash.h"

#include <miral/application_switcher.h>
#include <miral/display_configuration_option.h>
#include <miral/external_client.h>
#include <miral/runner.h>
#include <miral/window_management_options.h>
#include <miral/append_keyboard_event_filter.h>
#include <miral/internal_client.h>
#include <miral/command_line_option.h>
#include <miral/cursor_theme.h>
#include <miral/decorations.h>
#include <miral/keymap.h>
#include <miral/toolkit_event.h>
#include <miral/x11_support.h>
#include <miral/wayland_extensions.h>
#include <miral/mousekeys_config.h>
#include <miral/output_filter.h>
#include <miral/simulated_secondary_click.h>
#include <miral/hover_click.h>
#include <miral/sticky_keys.h>
#include <miral/magnifier.h>
#include <miral/cursor_scale.h>

#include <xkbcommon/xkbcommon-keysyms.h>

#include <cstring>
#include <linux/input-event-codes.h>

namespace
{
struct ConfigureDecorations
{
    miral::Decorations const decorations{[]
        {
            if (auto const strategy = getenv("MIRAL_SHELL_DECORATIONS"))
            {
                if (strcmp(strategy, "always-ssd") == 0) return miral::Decorations::always_ssd();
                if (strcmp(strategy, "prefer-ssd") == 0) return miral::Decorations::prefer_ssd();
                if (strcmp(strategy, "always-csd") == 0) return miral::Decorations::always_csd();
            }
            return miral::Decorations::prefer_csd();
        }()};

    void operator()(mir::Server& s) const
    {
        decorations(s);
    }
};
}

int main(int argc, char const* argv[])
{
    using namespace miral;
    using namespace miral::toolkit;

    std::function<void()> shutdown_hook{[]{}};

    SpinnerSplash spinner;
    InternalClientLauncher launcher;
    auto focus_stealing_prevention = FocusStealing::allow;
    WindowManagerOptions window_managers
        {
            add_window_manager_policy<FloatingWindowManagerPolicy>("floating", spinner, launcher, shutdown_hook, focus_stealing_prevention),
            add_window_manager_policy<TilingWindowManagerPolicy>("tiling", spinner, launcher),
        };

    MirRunner runner{argc, argv};

    runner.add_stop_callback([&] { shutdown_hook(); });

    ExternalClientLauncher external_client_launcher;

    std::string terminal_cmd{"miral-terminal"};

    auto const quit_on_ctrl_alt_bksp = [&](MirKeyboardEvent const* kev)
        {
            if (mir_keyboard_event_action(kev) != mir_keyboard_action_down)
                return false;

            MirInputEventModifiers mods = mir_keyboard_event_modifiers(kev);
            if (!(mods & mir_input_event_modifier_alt) || !(mods & mir_input_event_modifier_ctrl))
                return false;

            switch (mir_keyboard_event_keysym(kev))
            {
            case XKB_KEY_BackSpace:
                runner.stop();
                return true;

            case XKB_KEY_t:
            case XKB_KEY_T:
                external_client_launcher.launch({terminal_cmd});
                return true;

            case XKB_KEY_x:
            case XKB_KEY_X:
                external_client_launcher.launch_using_x11({"xterm"});
                return true;

            default:
                return false;
            };
        };

    Keymap config_keymap = getenv("MIRAL_SHELL_SYSTEM_LOCALE1") ? Keymap::system_locale1() : Keymap{};

    auto run_startup_apps = [&](std::string const& apps)
    {
      for (auto i = begin(apps); i != end(apps); )
      {
          auto const j = find(i, end(apps), ':');
          external_client_launcher.launch(std::vector<std::string>{std::string{i, j}});
          if ((i = j) != end(apps)) ++i;
      }
    };

    auto const to_focus_stealing = [](bool focus_stealing_prevention)
    {
        if (focus_stealing_prevention)
            return FocusStealing::prevent;
        else
            return FocusStealing::allow;
    };

    auto const initial_mousekeys_state = false;
    auto mousekeys_config = [&]
    {
        return initial_mousekeys_state ? MouseKeysConfig::enabled() : MouseKeysConfig::disabled();
    }();

    auto toggle_mousekeys_filter = [mousekeys_on = initial_mousekeys_state, &mousekeys_config](MirKeyboardEvent const* key_event) mutable {
        auto const modifiers = mir_keyboard_event_modifiers(key_event);

        if ((modifiers & mir_input_event_modifier_ctrl) && (modifiers & mir_input_event_modifier_shift) &&
            (modifiers & mir_input_event_modifier_num_lock))
        {
            if (mir_keyboard_event_action(key_event) == mir_keyboard_action_down ||
                mir_keyboard_event_action(key_event) == mir_keyboard_action_repeat)
                return true;

            mousekeys_on = !mousekeys_on;
            if(mousekeys_on)
                mousekeys_config.enable();
            else
                mousekeys_config.disable();

            return true;
        }

        return false;
    };

    miral::OutputFilter output_filter;
    auto toggle_output_filter_filter = [invert_on = false, &output_filter](MirKeyboardEvent const* key_event) mutable {
        auto const modifiers = mir_keyboard_event_modifiers(key_event);

        if (mir_keyboard_event_action(key_event) != mir_keyboard_action_down)
            return false;

        if (modifiers & mir_input_event_modifier_ctrl)
        {
            switch (mir_keyboard_event_keysym(key_event))
            {
            case XKB_KEY_i:
                invert_on = !invert_on;
                output_filter.filter(invert_on ? mir_output_filter_invert : mir_output_filter_none);
                return true;
            }
        }

        return false;
    };

    auto ssc_config = miral::SimulatedSecondaryClick::disabled()
                                .displacement_threshold(30)
                                .hold_duration(std::chrono::milliseconds{2000});

    auto hover_click_config = miral::HoverClick::disabled();

    float magnification = 2.f;
    Size capture_size{100, 100};
    auto magnifier = Magnifier()
        .magnification(magnification)
        .capture_size(capture_size)
        .enable(false);
    auto magnifier_filter = [magnifier=magnifier, &magnification, &capture_size](MirKeyboardEvent const* key_event) mutable {
        auto const modifiers = mir_keyboard_event_modifiers(key_event);

        if (mir_keyboard_event_action(key_event) != mir_keyboard_action_down)
            return false;

        if (modifiers & mir_input_event_modifier_ctrl)
        {
            if (modifiers & mir_input_event_modifier_shift)
            {
                // Zoom the magnifier in/out on ctrl shift +/-
                switch (mir_keyboard_event_keysym(key_event))
                {
                    case XKB_KEY_plus:
                        magnification += 0.5f;
                        if (magnification >= 5)
                        {
                            magnification = 5;
                            return true;
                        }

                        magnifier.magnification(magnification);
                        return true;
                    case XKB_KEY_underscore:
                        magnification -= 0.5f;
                        if (magnification <= 1)
                        {
                            magnification = 1;
                            return true;
                        }

                        magnifier.magnification(magnification);
                        return true;
                    default:
                        break;
                }
            }
            else if (modifiers & mir_input_event_modifier_alt)
            {
                // Grow area on ctrl alt +/-
                switch (mir_keyboard_event_keysym(key_event))
                {
                    case XKB_KEY_equal:
                    {
                        capture_size.width = Width(std::min(1000, capture_size.width.as_int() + 100));
                        capture_size.height = Height(std::min(1000, capture_size.height.as_int() + 100));
                        magnifier.capture_size(capture_size);
                        return true;
                    }
                    case XKB_KEY_minus:
                        capture_size.width = Width(std::max(100, capture_size.width.as_int() - 100));
                        capture_size.height = Height(std::max(100, capture_size.height.as_int() - 100));
                        magnifier.capture_size(capture_size);
                        return true;
                    default:
                        break;
                }
            }
            else
            {
                // Turn on/off the magnifier on ctrl +/-
                switch (mir_keyboard_event_keysym(key_event))
                {
                    case XKB_KEY_equal:
                        magnifier.enable(true);
                        return true;
                    case XKB_KEY_minus:
                        magnifier.enable(false);
                        return true;
                    default:
                        break;
                }
            }
        }

        return false;
    };

    StickyKeys sticky_keys = StickyKeys::disabled();
    auto const sticky_keys_filter = [sticky_keys=sticky_keys, sticky_keys_enabled=false](MirKeyboardEvent const* key_event) mutable
    {
        if (mir_keyboard_event_action(key_event) != mir_keyboard_action_up)
            return false;

        auto const modifiers = mir_keyboard_event_modifiers(key_event);
        if (modifiers & mir_input_event_modifier_ctrl && modifiers & mir_input_event_modifier_alt)
        {
            if (auto const keysym = mir_keyboard_event_keysym(key_event); keysym == XKB_KEY_s)
            {
                if (!sticky_keys_enabled)
                    sticky_keys.enable();
                else
                    sticky_keys.disable();

                sticky_keys_enabled = !sticky_keys_enabled;
                return true;
            }
        }

        return false;
    };

    auto cursor_scale = miral::CursorScale{1.0f};

    auto locate_pointer = miral::LocatePointer::enabled()
                              .on_locate_pointer([&cursor_scale](auto)
                                                 { cursor_scale.scale_temporarily(5, std::chrono::seconds{1}); })
                              .delay(std::chrono::milliseconds{1000});

    auto const locate_pointer_filter = [&locate_pointer](auto const* keyboard_event)
    {
        auto const keysym = mir_keyboard_event_keysym(keyboard_event);
        auto const action = mir_keyboard_event_action(keyboard_event);
        auto const modifiers = mir_keyboard_event_modifiers(keyboard_event);

        auto only_ctrl_down = [modifiers]
        {
            auto constexpr ctrls_mask = mir_input_event_modifier_ctrl | mir_input_event_modifier_ctrl_left |
                                    mir_input_event_modifier_ctrl_right;
            auto const any_ctrl_down = modifiers & ctrls_mask;
            auto const any_other_modifier_down = modifiers & ~ctrls_mask;

            return any_ctrl_down && !any_other_modifier_down;
        }();


        auto other_key_down = false;
        // If ctrl is the only modifier pressed, make sure the keysym is also ctrl
        if (only_ctrl_down)
        {
            switch (action)
            {
            case mir_keyboard_action_down:
                other_key_down = (keysym != XKB_KEY_Control_R && keysym != XKB_KEY_Control_L);
                break;
            case mir_keyboard_action_up:
                only_ctrl_down = false;
                break;

            default:
                break;
            }
        }

        if (only_ctrl_down && !other_key_down)
            locate_pointer.schedule_request();
        else
            locate_pointer.cancel_request();

        return false;
    };

    return runner.run_with(
        {
            CursorTheme{"default:DMZ-White"},
            WaylandExtensions{},
            X11Support{},
            ConfigureDecorations{},
            pre_init(ConfigurationOption{[&](bool is_set)
                    { focus_stealing_prevention = to_focus_stealing(is_set); },
                    "focus-stealing-prevention", "Prevent newly opened windows from taking keyboard focus from an active window.", false}),
            window_managers,
            display_configuration_options,
            external_client_launcher,
            launcher,
            config_keymap,
            AppendKeyboardEventFilter{quit_on_ctrl_alt_bksp},
            StartupInternalClient{spinner},
            ConfigurationOption{run_startup_apps, "startup-apps", "Colon separated list of startup apps", ""},
            pre_init(ConfigurationOption{[&](std::string const& typeface) { ::wallpaper::font_file(typeface); },
                                         "shell-wallpaper-font", "Font file to use for wallpaper.", ::wallpaper::font_file()}),
            ConfigurationOption{[&](std::string const& cmd) { terminal_cmd = cmd; },
                                "shell-terminal-emulator", "Terminal emulator to use.", terminal_cmd},
            mousekeys_config,
            AppendKeyboardEventFilter{toggle_mousekeys_filter},
            output_filter,
            AppendKeyboardEventFilter{toggle_output_filter_filter},
            ssc_config,
            hover_click_config,
            sticky_keys,
            magnifier,
            AppendKeyboardEventFilter{magnifier_filter},
            AppendKeyboardEventFilter{sticky_keys_filter},
            cursor_scale,
            locate_pointer,
            AppendKeyboardEventFilter{locate_pointer_filter},
            BasicApplicationSwitcher{}
        });
}