#include <SDL2/SDL.h>

#include "input.h"


static SDL_GameController* sdl_find_gamepad() {
    int i = SDL_NumJoysticks() - 1;
    printf("Found %d joysticks\n", i + 1);
    for ( ; i >= 0 && !SDL_IsGameController(i); --i);
    if (i >= 0) printf("Joystick %d is a gamepad\n", i);
    return (i < 0 ? NULL : SDL_GameControllerOpen(i));
}

static void sdl_lose_gamepad(void* data) {
    SDL_GameController* gamepad = (SDL_GameController*)data;
    if (NULL != gamepad) SDL_GameControllerClose(gamepad);
}

static int sdl_match_gamepad(SDL_JoystickID id, void* data) {
    SDL_GameController* gamepad = (SDL_GameController*)data;
    return (    SDL_JoystickInstanceID(
                        SDL_GameControllerGetJoystick(gamepad))
                    == id);
}
/*
static int sdl_event_filter(void*, SDL_Event* event) {
    return (    SDL_QUIT == event->type ||
                SDL_KEYDOWN == event->type ||
                SDL_KEYUP == event->type ||
                SDL_CONTROLLERBUTTONDOWN == event->type ||
                SDL_CONTROLLERBUTTONUP == event->type ||
                SDL_CONTROLLERDEVICEADDED == event->type ||
                SDL_CONTROLLERDEVICEREMOVED == event->type
            );
}
*/
static int sdl_input_init(nes_Input_Reader* reader) {
    int status = SDL_Init(SDL_INIT_EVENTS |
                          SDL_INIT_GAMECONTROLLER);

    if (status == 0) {
        reader->data = sdl_find_gamepad();
//        SDL_SetEventFilter(sdl_event_filter, NULL);
        if (NULL != reader->data) {
            printf("Gamepad found\n");
        }
    }

    return status;
}

static void sdl_input_done(nes_Input_Reader* input) {
    sdl_lose_gamepad(input->data);
}

static const int sdl_reset_key = SDLK_ESCAPE;
static const int sdl_save_key = SDLK_F1;
static const int sdl_load_key = SDLK_F2;

static const int sdl_keycodes[nes_controller_num_buttons] = {
    SDLK_a,
    SDLK_s,
    SDLK_q,
    SDLK_w,
    SDLK_UP,
    SDLK_DOWN,
    SDLK_LEFT,
    SDLK_RIGHT,
};

static const int sdl_save_button = SDL_CONTROLLER_BUTTON_LEFTSHOULDER;
static const int sdl_load_button = SDL_CONTROLLER_BUTTON_RIGHTSHOULDER;

static const int sdl_buttons[nes_controller_num_buttons] = {
    SDL_CONTROLLER_BUTTON_A,
    SDL_CONTROLLER_BUTTON_B,
    SDL_CONTROLLER_BUTTON_BACK,
    SDL_CONTROLLER_BUTTON_START,
    SDL_CONTROLLER_BUTTON_DPAD_UP,
    SDL_CONTROLLER_BUTTON_DPAD_DOWN,
    SDL_CONTROLLER_BUTTON_DPAD_LEFT,
    SDL_CONTROLLER_BUTTON_DPAD_RIGHT,
};

static int button_index(int keycode, const int* codes) {
    int index = nes_controller_num_buttons - 1;
    for ( ; index >= 0 && keycode != codes[index]; --index);
    return index;
}

static int sdl_input_update(nes_Input_Reader* reader,
                            nes_input* input) {
    int status = input_Result_OK;

    SDL_Event event = {0};
    while (0 == status && 0 != SDL_PollEvent(&event)) {
        if (SDL_QUIT == event.type) {
            status = input_Result_Quit;

        } else if ( (   SDL_KEYDOWN == event.type ||
                        SDL_KEYUP == event.type) &&
                    0 == event.key.repeat
                ) {
            int index = button_index(event.key.keysym.sym,
                                     sdl_keycodes);
            if (index >= 0) {
                uint8_t mask = (1 << index);
                if (SDL_KEYDOWN == event.type) {
                    input->controllers[0].buttons |= mask;
                } else {
                    input->controllers[0].buttons &= ~mask;
                }

            } else if ( sdl_reset_key == event.key.keysym.sym &&
                        SDL_KEYDOWN == event.type) {
                status = input_Result_Reset;

            } else if (sdl_save_key == event.key.keysym.sym) {
                if (SDL_KEYDOWN == event.type) {
                    status = input_Result_Save;
                } else {
                    status = input_Result_Cancel;
                }

            } else if (sdl_load_key == event.key.keysym.sym) {
                if (SDL_KEYDOWN == event.type) {
                    status = input_Result_Load;
                } else {
                    status = input_Result_Cancel;
                }
            }

        } else if ( SDL_CONTROLLERBUTTONDOWN == event.type ||
                    SDL_CONTROLLERBUTTONUP == event.type) {
            int index = button_index(event.cbutton.button,
                                     sdl_buttons);
            if (index >= 0) {
                uint8_t mask = (1 << index);
                if (SDL_CONTROLLERBUTTONDOWN == event.type) {
                    input->controllers[0].buttons |= mask;
                } else {
                    input->controllers[0].buttons &= ~mask;
                }

            } else if (sdl_save_button == event.cbutton.button) {
                if (SDL_CONTROLLERBUTTONDOWN == event.type) {
                    status = input_Result_Save;
                } else {
                    status = input_Result_Cancel;
                }

            } else if (sdl_load_button == event.cbutton.button) {
                if (SDL_CONTROLLERBUTTONDOWN == event.type) {
                    status = input_Result_Load;
                } else {
                    status = input_Result_Cancel;
                }
            }

        } else if (SDL_CONTROLLERAXISMOTION == event.type) {
            const uint8_t axis = event.caxis.axis;
            const int16_t value = event.caxis.value;
            uint8_t mask_set = 0;
            uint8_t mask_clear = 0;

            if (SDL_CONTROLLER_AXIS_LEFTX == axis) {
                mask_clear = (1 << Button_Left) |
                             (1 << Button_Right);
                if (value <= -8192) {
                    mask_set = (1 << Button_Left);
                } else if (value >= 8192) {
                    mask_set = (1 << Button_Right);
                }

            } else if (SDL_CONTROLLER_AXIS_LEFTY == axis) {
                mask_clear = (1 << Button_Down) |
                             (1 << Button_Up);
                if (value <= -8192) {
                    mask_set = (1 << Button_Up);
                } else if (value >= 8192) {
                    mask_set = (1 << Button_Down);
                }
            }

            input->controllers[0].buttons &= ~mask_clear;
            input->controllers[0].buttons |= mask_set;

        } else if (SDL_CONTROLLERDEVICEADDED == event.type) {
            if (NULL == reader->data) {
                printf("New gamepad connected\n");
                reader->data = sdl_find_gamepad();
                if (reader->data) printf("Using new gamepad\n");
            } else {
                printf("Redundant gamepad connected\n");
            }

        } else if (SDL_CONTROLLERDEVICEREMOVED == event.type) {
            if (sdl_match_gamepad(event.cdevice.which,
                                  reader->data)) {
                printf("Gamepad disconnected\n");
                sdl_lose_gamepad(reader->data);
                reader->data = sdl_find_gamepad();
                if (reader->data) printf("Using another gamepad\n");
            } else {
                printf("Redundant gamepad disconnected\n");
            }
        }
    }

    return status;
}


nes_Input_Reader sdl_input = {
    .init   = sdl_input_init,
    .done   = sdl_input_done,
    .update = sdl_input_update,
};