// dear imgui: Platform Binding for Android native app
// This needs to be used along with the OpenGL 3 Renderer (imgui_impl_opengl3)

// Implemented features:
//  [X] Platform: Keyboard support. Since 1.87 we are using the io.AddKeyEvent() function. Pass ImGuiKey values to all key functions e.g. ImGui::IsKeyPressed(ImGuiKey_Space). [Legacy AKEYCODE_* values will also be supported unless IMGUI_DISABLE_OBSOLETE_KEYIO is set]
// Missing features:
//  [ ] Platform: Clipboard support.
//  [ ] Platform: Gamepad support. Enable with 'io.ConfigFlags |= ImGuiConfigFlags_NavEnableGamepad'.
//  [ ] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'. FIXME: Check if this is even possible with Android.
// Important:
//  - Consider using SDL or GLFW backend on Android, which will be more full-featured than this.
//  - FIXME: On-screen keyboard currently needs to be enabled by the application (see examples/ and issue #3446)
//  - FIXME: Unicode character inputs needs to be passed by Dear ImGui by the application (see examples/ and issue #3446)

// You can use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
// Prefer including the entire imgui/ repository into your project (either as a copy or as a submodule), and only build the backends you need.
// If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
// Read online: https://github.com/ocornut/imgui/tree/master/docs

// CHANGELOG
// (minor and older changes stripped away, please see git history for details)
//  2022-01-10: Inputs: calling new io.AddKeyEvent(), io.AddKeyModsEvent() + io.SetKeyEventNativeData() API (1.87+). Support for full ImGuiKey range.
//  2021-03-04: Initial version.

#include "imgui.h"
#include "imgui_impl_android.h"
#include <time.h>
#include <map>
#include <queue>
#include <android/native_window.h>
#include <android/input.h>
#include <android/keycodes.h>
#include <android/log.h>

struct KeyEvent
{
    ImGuiKey Key;
    bool     Down;
    int      NativeKeycode;
    int      NativeScancode;

    KeyEvent(): Key(ImGuiKey_None), Down(false), NativeKeycode(-1), NativeScancode(-1) {}
};

// Android data
static double                                   g_Time = 0.0;
static ANativeWindow*                           g_Window;
static char                                     g_LogTag[] = "ImGuiExample";
static std::map<ImGuiKey, std::queue<KeyEvent>> g_KeyEventQueues; // FIXME: Remove dependency on map and queue once we use upcoming input queue.
static ImGuiKeyModFlags                         g_KeyModFlags = ImGuiKeyModFlags_None;

static ImGuiKey ImGui_ImplAndroid_KeyCodeToImGuiKey(int32_t key_code)
{
    switch (key_code)
    {
        case AKEYCODE_TAB:                  return ImGuiKey_Tab;
        case AKEYCODE_DPAD_LEFT:            return ImGuiKey_LeftArrow;
        case AKEYCODE_DPAD_RIGHT:           return ImGuiKey_RightArrow;
        case AKEYCODE_DPAD_UP:              return ImGuiKey_UpArrow;
        case AKEYCODE_DPAD_DOWN:            return ImGuiKey_DownArrow;
        case AKEYCODE_PAGE_UP:              return ImGuiKey_PageUp;
        case AKEYCODE_PAGE_DOWN:            return ImGuiKey_PageDown;
        case AKEYCODE_MOVE_HOME:            return ImGuiKey_Home;
        case AKEYCODE_MOVE_END:             return ImGuiKey_End;
        case AKEYCODE_INSERT:               return ImGuiKey_Insert;
        case AKEYCODE_FORWARD_DEL:          return ImGuiKey_Delete;
        case AKEYCODE_DEL:                  return ImGuiKey_Backspace;
        case AKEYCODE_SPACE:                return ImGuiKey_Space;
        case AKEYCODE_ENTER:                return ImGuiKey_Enter;
        case AKEYCODE_ESCAPE:               return ImGuiKey_Escape;
        case AKEYCODE_APOSTROPHE:           return ImGuiKey_Apostrophe;
        case AKEYCODE_COMMA:                return ImGuiKey_Comma;
        case AKEYCODE_MINUS:                return ImGuiKey_Minus;
        case AKEYCODE_PERIOD:               return ImGuiKey_Period;
        case AKEYCODE_SLASH:                return ImGuiKey_Slash;
        case AKEYCODE_SEMICOLON:            return ImGuiKey_Semicolon;
        case AKEYCODE_EQUALS:               return ImGuiKey_Equal;
        case AKEYCODE_LEFT_BRACKET:         return ImGuiKey_LeftBracket;
        case AKEYCODE_BACKSLASH:            return ImGuiKey_Backslash;
        case AKEYCODE_RIGHT_BRACKET:        return ImGuiKey_RightBracket;
        case AKEYCODE_GRAVE:                return ImGuiKey_GraveAccent;
        case AKEYCODE_CAPS_LOCK:            return ImGuiKey_CapsLock;
        case AKEYCODE_SCROLL_LOCK:          return ImGuiKey_ScrollLock;
        case AKEYCODE_NUM_LOCK:             return ImGuiKey_NumLock;
        case AKEYCODE_SYSRQ:                return ImGuiKey_PrintScreen;
        case AKEYCODE_BREAK:                return ImGuiKey_Pause;
        case AKEYCODE_NUMPAD_0:             return ImGuiKey_Keypad0;
        case AKEYCODE_NUMPAD_1:             return ImGuiKey_Keypad1;
        case AKEYCODE_NUMPAD_2:             return ImGuiKey_Keypad2;
        case AKEYCODE_NUMPAD_3:             return ImGuiKey_Keypad3;
        case AKEYCODE_NUMPAD_4:             return ImGuiKey_Keypad4;
        case AKEYCODE_NUMPAD_5:             return ImGuiKey_Keypad5;
        case AKEYCODE_NUMPAD_6:             return ImGuiKey_Keypad6;
        case AKEYCODE_NUMPAD_7:             return ImGuiKey_Keypad7;
        case AKEYCODE_NUMPAD_8:             return ImGuiKey_Keypad8;
        case AKEYCODE_NUMPAD_9:             return ImGuiKey_Keypad9;
        case AKEYCODE_NUMPAD_DOT:           return ImGuiKey_KeypadDecimal;
        case AKEYCODE_NUMPAD_DIVIDE:        return ImGuiKey_KeypadDivide;
        case AKEYCODE_NUMPAD_MULTIPLY:      return ImGuiKey_KeypadMultiply;
        case AKEYCODE_NUMPAD_SUBTRACT:      return ImGuiKey_KeypadSubtract;
        case AKEYCODE_NUMPAD_ADD:           return ImGuiKey_KeypadAdd;
        case AKEYCODE_NUMPAD_ENTER:         return ImGuiKey_KeypadEnter;
        case AKEYCODE_NUMPAD_EQUALS:        return ImGuiKey_KeypadEqual;
        case AKEYCODE_SHIFT_LEFT:           return ImGuiKey_LeftShift;
        case AKEYCODE_CTRL_LEFT:            return ImGuiKey_LeftControl;
        case AKEYCODE_ALT_LEFT:             return ImGuiKey_LeftAlt;
        case AKEYCODE_META_LEFT:            return ImGuiKey_LeftSuper;
        case AKEYCODE_SHIFT_RIGHT:          return ImGuiKey_RightShift;
        case AKEYCODE_CTRL_RIGHT:           return ImGuiKey_RightControl;
        case AKEYCODE_ALT_RIGHT:            return ImGuiKey_RightAlt;
        case AKEYCODE_META_RIGHT:           return ImGuiKey_RightSuper;
        case AKEYCODE_MENU:                 return ImGuiKey_Menu;
        case AKEYCODE_0:                    return ImGuiKey_0;
        case AKEYCODE_1:                    return ImGuiKey_1;
        case AKEYCODE_2:                    return ImGuiKey_2;
        case AKEYCODE_3:                    return ImGuiKey_3;
        case AKEYCODE_4:                    return ImGuiKey_4;
        case AKEYCODE_5:                    return ImGuiKey_5;
        case AKEYCODE_6:                    return ImGuiKey_6;
        case AKEYCODE_7:                    return ImGuiKey_7;
        case AKEYCODE_8:                    return ImGuiKey_8;
        case AKEYCODE_9:                    return ImGuiKey_9;
        case AKEYCODE_A:                    return ImGuiKey_A;
        case AKEYCODE_B:                    return ImGuiKey_B;
        case AKEYCODE_C:                    return ImGuiKey_C;
        case AKEYCODE_D:                    return ImGuiKey_D;
        case AKEYCODE_E:                    return ImGuiKey_E;
        case AKEYCODE_F:                    return ImGuiKey_F;
        case AKEYCODE_G:                    return ImGuiKey_G;
        case AKEYCODE_H:                    return ImGuiKey_H;
        case AKEYCODE_I:                    return ImGuiKey_I;
        case AKEYCODE_J:                    return ImGuiKey_J;
        case AKEYCODE_K:                    return ImGuiKey_K;
        case AKEYCODE_L:                    return ImGuiKey_L;
        case AKEYCODE_M:                    return ImGuiKey_M;
        case AKEYCODE_N:                    return ImGuiKey_N;
        case AKEYCODE_O:                    return ImGuiKey_O;
        case AKEYCODE_P:                    return ImGuiKey_P;
        case AKEYCODE_Q:                    return ImGuiKey_Q;
        case AKEYCODE_R:                    return ImGuiKey_R;
        case AKEYCODE_S:                    return ImGuiKey_S;
        case AKEYCODE_T:                    return ImGuiKey_T;
        case AKEYCODE_U:                    return ImGuiKey_U;
        case AKEYCODE_V:                    return ImGuiKey_V;
        case AKEYCODE_W:                    return ImGuiKey_W;
        case AKEYCODE_X:                    return ImGuiKey_X;
        case AKEYCODE_Y:                    return ImGuiKey_Y;
        case AKEYCODE_Z:                    return ImGuiKey_Z;
        case AKEYCODE_F1:                   return ImGuiKey_F1;
        case AKEYCODE_F2:                   return ImGuiKey_F2;
        case AKEYCODE_F3:                   return ImGuiKey_F3;
        case AKEYCODE_F4:                   return ImGuiKey_F4;
        case AKEYCODE_F5:                   return ImGuiKey_F5;
        case AKEYCODE_F6:                   return ImGuiKey_F6;
        case AKEYCODE_F7:                   return ImGuiKey_F7;
        case AKEYCODE_F8:                   return ImGuiKey_F8;
        case AKEYCODE_F9:                   return ImGuiKey_F9;
        case AKEYCODE_F10:                  return ImGuiKey_F10;
        case AKEYCODE_F11:                  return ImGuiKey_F11;
        case AKEYCODE_F12:                  return ImGuiKey_F12;
        default:                            return ImGuiKey_None;
    }
}

int32_t ImGui_ImplAndroid_HandleInputEvent(AInputEvent* input_event)
{
    ImGuiIO& io = ImGui::GetIO();
    int32_t event_type = AInputEvent_getType(input_event);
    switch (event_type)
    {
    case AINPUT_EVENT_TYPE_KEY:
    {
        int32_t event_key_code = AKeyEvent_getKeyCode(input_event);
        int32_t event_scan_code = AKeyEvent_getScanCode(input_event);
        int32_t event_action = AKeyEvent_getAction(input_event);
        int32_t event_meta_state = AKeyEvent_getMetaState(input_event);

        g_KeyModFlags = ImGuiKeyModFlags_None;
        if ((event_meta_state & AMETA_CTRL_ON) != 0)
            g_KeyModFlags |= ImGuiKeyModFlags_Ctrl;
        if ((event_meta_state & AMETA_SHIFT_ON) != 0)
            g_KeyModFlags |= ImGuiKeyModFlags_Shift;
        if ((event_meta_state & AMETA_ALT_ON) != 0)
            g_KeyModFlags |= ImGuiKeyModFlags_Alt;
        if ((event_meta_state & AMETA_META_ON) != 0)
            g_KeyModFlags |= ImGuiKeyModFlags_Super;

        switch (event_action)
        {
        // FIXME: AKEY_EVENT_ACTION_DOWN and AKEY_EVENT_ACTION_UP occur at once as soon as a touch pointer
        // goes up from a key. We use a simple key event queue/ and process one event per key per frame in
        // ImGui_ImplAndroid_NewFrame()...or consider using IO queue, if suitable: https://github.com/ocornut/imgui/issues/2787
        case AKEY_EVENT_ACTION_DOWN:
        case AKEY_EVENT_ACTION_UP:
        {
            ImGuiKey key = ImGui_ImplAndroid_KeyCodeToImGuiKey(event_key_code);
            if (key != ImGuiKey_None && (event_action == AKEY_EVENT_ACTION_DOWN || event_action == AKEY_EVENT_ACTION_UP))
            {
                KeyEvent io_event;
                io_event.Key = key;
                io_event.Down = event_action == AKEY_EVENT_ACTION_DOWN;
                io_event.NativeKeycode = event_key_code;
                io_event.NativeScancode = event_scan_code;

                g_KeyEventQueues[key].push(io_event);
            }

            break;
        }
        default:
            break;
        }
        break;
    }
    case AINPUT_EVENT_TYPE_MOTION:
    {
        int32_t event_action = AMotionEvent_getAction(input_event);
        int32_t event_pointer_index = (event_action & AMOTION_EVENT_ACTION_POINTER_INDEX_MASK) >> AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
        event_action &= AMOTION_EVENT_ACTION_MASK;
        switch (event_action)
        {
        case AMOTION_EVENT_ACTION_DOWN:
        case AMOTION_EVENT_ACTION_UP:
            // Physical mouse buttons (and probably other physical devices) also invoke the actions AMOTION_EVENT_ACTION_DOWN/_UP,
            // but we have to process them separately to identify the actual button pressed. This is done below via
            // AMOTION_EVENT_ACTION_BUTTON_PRESS/_RELEASE. Here, we only process "FINGER" input (and "UNKNOWN", as a fallback).
            if((AMotionEvent_getToolType(input_event, event_pointer_index) == AMOTION_EVENT_TOOL_TYPE_FINGER)
            || (AMotionEvent_getToolType(input_event, event_pointer_index) == AMOTION_EVENT_TOOL_TYPE_UNKNOWN))
            {
                io.MouseDown[0] = (event_action == AMOTION_EVENT_ACTION_DOWN);
                io.MousePos = ImVec2(AMotionEvent_getX(input_event, event_pointer_index), AMotionEvent_getY(input_event, event_pointer_index));
            }
            break;
        case AMOTION_EVENT_ACTION_BUTTON_PRESS:
        case AMOTION_EVENT_ACTION_BUTTON_RELEASE:
            {
                int32_t button_state = AMotionEvent_getButtonState(input_event);
                io.MouseDown[0] = ((button_state & AMOTION_EVENT_BUTTON_PRIMARY) != 0);
                io.MouseDown[1] = ((button_state & AMOTION_EVENT_BUTTON_SECONDARY) != 0);
                io.MouseDown[2] = ((button_state & AMOTION_EVENT_BUTTON_TERTIARY) != 0);
            }
            break;
        case AMOTION_EVENT_ACTION_HOVER_MOVE: // Hovering: Tool moves while NOT pressed (such as a physical mouse)
        case AMOTION_EVENT_ACTION_MOVE:       // Touch pointer moves while DOWN
            io.MousePos = ImVec2(AMotionEvent_getX(input_event, event_pointer_index), AMotionEvent_getY(input_event, event_pointer_index));
            break;
        case AMOTION_EVENT_ACTION_SCROLL:
            io.MouseWheel = AMotionEvent_getAxisValue(input_event, AMOTION_EVENT_AXIS_VSCROLL, event_pointer_index);
            io.MouseWheelH = AMotionEvent_getAxisValue(input_event, AMOTION_EVENT_AXIS_HSCROLL, event_pointer_index);
            break;
        default:
            break;
        }
    }
        return 1;
    default:
        break;
    }

    return 0;
}

bool ImGui_ImplAndroid_Init(ANativeWindow* window)
{
    g_Window = window;
    g_Time = 0.0;

    // Setup backend capabilities flags
    ImGuiIO& io = ImGui::GetIO();
    io.BackendPlatformName = "imgui_impl_android";

    return true;
}

void ImGui_ImplAndroid_Shutdown()
{
}

void ImGui_ImplAndroid_NewFrame()
{
    ImGuiIO& io = ImGui::GetIO();

    // Process queued key events
    // FIXME: This is a workaround for multiple key event actions occurring at once (see above) and can be removed once we use upcoming input queue.
    for (auto& key_queue : g_KeyEventQueues)
    {
        if (key_queue.second.empty())
            continue;

        auto& key_event = key_queue.second.front();
        io.AddKeyEvent(key_event.Key, key_event.Down);
        io.SetKeyEventNativeData(key_event.Key, key_event.NativeKeycode, key_event.NativeScancode); // To support legacy indexing (<1.87 user code)
        key_queue.second.pop();
    }
    io.AddKeyModsEvent(g_KeyModFlags);

    // Setup display size (every frame to accommodate for window resizing)
    int32_t window_width = ANativeWindow_getWidth(g_Window);
    int32_t window_height = ANativeWindow_getHeight(g_Window);
    int display_width = window_width;
    int display_height = window_height;

    io.DisplaySize = ImVec2((float)window_width, (float)window_height);
    if (window_width > 0 && window_height > 0)
        io.DisplayFramebufferScale = ImVec2((float)display_width / window_width, (float)display_height / window_height);

    // Setup time step
    struct timespec current_timespec;
    clock_gettime(CLOCK_MONOTONIC, &current_timespec);
    double current_time = (double)(current_timespec.tv_sec) + (current_timespec.tv_nsec / 1000000000.0);
    io.DeltaTime = g_Time > 0.0 ? (float)(current_time - g_Time) : (float)(1.0f / 60.0f);
    g_Time = current_time;
}