/*
 * SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Unlicense OR CC0-1.0
 */

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_err.h"
#include "esp_log.h"
#include "usb/usb_host.h"
#include "errno.h"
#include "driver/gpio.h"

#include "hid_host.h"
#include "hid_usage_keyboard.h"
#include "hid_usage_mouse.h"

#define APP_QUIT_PIN                GPIO_NUM_0
#define APP_QUIT_PIN_POLL_MS        500

#define READY_TO_UNINSTALL          (HOST_NO_CLIENT | HOST_ALL_FREE)

/* Main char symbol for ENTER key */
#define KEYBOARD_ENTER_MAIN_CHAR    '\r'
/* When set to 1 pressing ENTER will be extending with LineFeed during serial debug output */
#define KEYBOARD_ENTER_LF_EXTEND    1

/**
 * @brief Application Event from USB Host driver
 *
 */
typedef enum {
    HOST_NO_CLIENT = 0x1,
    HOST_ALL_FREE = 0x2,
    DEVICE_CONNECTED = 0x4,
    DEVICE_DISCONNECTED = 0x8,
    DEVICE_ADDRESS_MASK = 0xFF0,
} app_event_t;

/**
 * @brief Key event
 *
 */
typedef struct {
    enum key_state {
        KEY_STATE_PRESSED = 0x00,
        KEY_STATE_RELEASED = 0x01
    } state;
    uint8_t modifier;
    uint8_t key_code;
} key_event_t;

#define USB_EVENTS_TO_WAIT      (DEVICE_CONNECTED | DEVICE_ADDRESS_MASK | DEVICE_DISCONNECTED)

static const char *TAG = "example";
static EventGroupHandle_t usb_flags;
static bool hid_device_connected = false;

hid_host_interface_handle_t keyboard_handle = NULL;
hid_host_interface_handle_t mouse_handle = NULL;

/**
 * @brief Scancode to ascii table
 */
const uint8_t keycode2ascii [57][2] = {
    {0, 0}, /* HID_KEY_NO_PRESS        */
    {0, 0}, /* HID_KEY_ROLLOVER        */
    {0, 0}, /* HID_KEY_POST_FAIL       */
    {0, 0}, /* HID_KEY_ERROR_UNDEFINED */
    {'a', 'A'}, /* HID_KEY_A               */
    {'b', 'B'}, /* HID_KEY_B               */
    {'c', 'C'}, /* HID_KEY_C               */
    {'d', 'D'}, /* HID_KEY_D               */
    {'e', 'E'}, /* HID_KEY_E               */
    {'f', 'F'}, /* HID_KEY_F               */
    {'g', 'G'}, /* HID_KEY_G               */
    {'h', 'H'}, /* HID_KEY_H               */
    {'i', 'I'}, /* HID_KEY_I               */
    {'j', 'J'}, /* HID_KEY_J               */
    {'k', 'K'}, /* HID_KEY_K               */
    {'l', 'L'}, /* HID_KEY_L               */
    {'m', 'M'}, /* HID_KEY_M               */
    {'n', 'N'}, /* HID_KEY_N               */
    {'o', 'O'}, /* HID_KEY_O               */
    {'p', 'P'}, /* HID_KEY_P               */
    {'q', 'Q'}, /* HID_KEY_Q               */
    {'r', 'R'}, /* HID_KEY_R               */
    {'s', 'S'}, /* HID_KEY_S               */
    {'t', 'T'}, /* HID_KEY_T               */
    {'u', 'U'}, /* HID_KEY_U               */
    {'v', 'V'}, /* HID_KEY_V               */
    {'w', 'W'}, /* HID_KEY_W               */
    {'x', 'X'}, /* HID_KEY_X               */
    {'y', 'Y'}, /* HID_KEY_Y               */
    {'z', 'Z'}, /* HID_KEY_Z               */
    {'1', '!'}, /* HID_KEY_1               */
    {'2', '@'}, /* HID_KEY_2               */
    {'3', '#'}, /* HID_KEY_3               */
    {'4', '$'}, /* HID_KEY_4               */
    {'5', '%'}, /* HID_KEY_5               */
    {'6', '^'}, /* HID_KEY_6               */
    {'7', '&'}, /* HID_KEY_7               */
    {'8', '*'}, /* HID_KEY_8               */
    {'9', '('}, /* HID_KEY_9               */
    {'0', ')'}, /* HID_KEY_0               */
    {KEYBOARD_ENTER_MAIN_CHAR, KEYBOARD_ENTER_MAIN_CHAR}, /* HID_KEY_ENTER           */
    {0, 0}, /* HID_KEY_ESC             */
    {'\b', 0}, /* HID_KEY_DEL             */
    {0, 0}, /* HID_KEY_TAB             */
    {' ', ' '}, /* HID_KEY_SPACE           */
    {'-', '_'}, /* HID_KEY_MINUS           */
    {'=', '+'}, /* HID_KEY_EQUAL           */
    {'[', '{'}, /* HID_KEY_OPEN_BRACKET    */
    {']', '}'}, /* HID_KEY_CLOSE_BRACKET   */
    {'\\', '|'}, /* HID_KEY_BACK_SLASH      */
    {'\\', '|'}, /* HID_KEY_SHARP           */  // HOTFIX: for NonUS Keyboards repeat HID_KEY_BACK_SLASH
    {';', ':'}, /* HID_KEY_COLON           */
    {'\'', '"'}, /* HID_KEY_QUOTE           */
    {'`', '~'}, /* HID_KEY_TILDE           */
    {',', '<'}, /* HID_KEY_LESS            */
    {'.', '>'}, /* HID_KEY_GREATER         */
    {'/', '?'} /* HID_KEY_SLASH           */
};

/**
 * @brief Makes new line depending on report output protocol type
 *
 * @param[in] proto Current protocol to output
 */
static void hid_print_new_device_report_header(hid_protocol_t proto)
{
    static hid_protocol_t prev_proto_output = HID_PROTOCOL_NONE;

    if (prev_proto_output != proto) {
        prev_proto_output = proto;
        printf("\r\n");
        if (proto == HID_PROTOCOL_MOUSE) {
            printf("Mouse\r\n");
        }
        if (proto == HID_PROTOCOL_KEYBOARD) {
            printf("Keyboard\r\n");
        }
        fflush(stdout);
    }
}

/**
 * @brief HID Keyboard modifier verification for capitalization application (right or left shift)
 *
 * @param[in] modifier
 * @return true  Modifier was pressed (left or right shift)
 * @return false Modifier was not pressed (left or right shift)
 *
 */
static inline bool hid_keyboard_is_modifier_shift(uint8_t modifier)
{
    if ((modifier && HID_LEFT_SHIFT) ||
            (modifier && HID_RIGHT_SHIFT)) {
        return true;
    }
    return false;
}

/**
 * @brief HID Keyboard get char symbol from key code
 *
 * @param[in] modifier  Keyboard modifier data
 * @param[in] key_code  Keyboard key code
 * @param[in] key_char  Pointer to key char data
 *
 * @return true  Key scancode converted successfully
 * @return false Key scancode unknown
 */
static inline bool hid_keyboard_get_char(uint8_t modifier,
        uint8_t key_code,
        unsigned char *key_char)
{
    uint8_t mod = (hid_keyboard_is_modifier_shift(modifier)) ? 1 : 0;

    if ((key_code >= HID_KEY_A) && (key_code <= HID_KEY_SLASH)) {
        *key_char = keycode2ascii[key_code][mod];
    } else {
        // All other key pressed
        return false;
    }

    return true;
}

/**
 * @brief HID Keyboard print char symbol
 *
 * @param[in] key_char  Keyboard char to stdout
 */
static inline void hid_keyboard_print_char(unsigned int key_char)
{
    if (!!key_char) {
        putchar(key_char);
#if (KEYBOARD_ENTER_LF_EXTEND)
        if (KEYBOARD_ENTER_MAIN_CHAR == key_char) {
            putchar('\n');
        }
#endif // KEYBOARD_ENTER_LF_EXTEND
        fflush(stdout);
    }
}

/**
 * @brief Key Event. Key event with the key code, state and modifier.
 *
 * @param[in] key_event Pointer to Key Event structure
 *
 */
static void key_event_callback(key_event_t *key_event)
{
    unsigned char key_char;

    hid_print_new_device_report_header(HID_PROTOCOL_KEYBOARD);

    if (KEY_STATE_PRESSED == key_event->state) {
        if (hid_keyboard_get_char(key_event->modifier,
                                  key_event->key_code, &key_char)) {

            hid_keyboard_print_char(key_char);

        }
    }
}

/**
 * @brief Key buffer scan code search.
 *
 * @param[in] src       Pointer to source buffer where to search
 * @param[in] key       Key scancode to search
 * @param[in] length    Size of the source buffer
 */
static inline bool key_found(const uint8_t *const src,
                             uint8_t key,
                             unsigned int length)
{
    for (unsigned int i = 0; i < length; i++) {
        if (src[i] == key) {
            return true;
        }
    }
    return false;
}

/**
 * @brief USB HID Host Keyboard Interface report callback handler
 *
 * @param[in] data    Pointer to input report data buffer
 * @param[in] length  Length of input report data buffer
 */
static void hid_host_keyboard_report_callback(const uint8_t *const data, const int length)
{
    hid_keyboard_input_report_boot_t *kb_report = (hid_keyboard_input_report_boot_t *)data;

    if (length < sizeof(hid_keyboard_input_report_boot_t)) {
        return;
    }

    static uint8_t prev_keys[HID_KEYBOARD_KEY_MAX] = { 0 };
    key_event_t key_event;

    for (int i = 0; i < HID_KEYBOARD_KEY_MAX; i++) {

        // key has been released verification
        if (prev_keys[i] > HID_KEY_ERROR_UNDEFINED &&
                !key_found(kb_report->key, prev_keys[i], HID_KEYBOARD_KEY_MAX)) {
            key_event.key_code = prev_keys[i];
            key_event.modifier = 0;
            key_event.state = KEY_STATE_RELEASED;
            key_event_callback(&key_event);
        }

        // key has been pressed verification
        if (kb_report->key[i] > HID_KEY_ERROR_UNDEFINED &&
                !key_found(prev_keys, kb_report->key[i], HID_KEYBOARD_KEY_MAX)) {
            key_event.key_code = kb_report->key[i];
            key_event.modifier = kb_report->modifier.val;
            key_event.state = KEY_STATE_PRESSED;
            key_event_callback(&key_event);
        }
    }

    memcpy(prev_keys, &kb_report->key, HID_KEYBOARD_KEY_MAX);
}

/**
 * @brief USB HID Host Mouse Interface report callback handler
 *
 * @param[in] data    Pointer to input report data buffer
 * @param[in] length  Length of input report data buffer
 */
static void hid_host_mouse_report_callback(const uint8_t *const data, const int length)
{
    hid_mouse_input_report_boot_t *mouse_report = (hid_mouse_input_report_boot_t *)data;

    if (length < sizeof(hid_mouse_input_report_boot_t)) {
        return;
    }

    static int x_pos = 0;
    static int y_pos = 0;

    // Calculate absolute position from displacement
    x_pos += mouse_report->x_displacement;
    y_pos += mouse_report->y_displacement;

    hid_print_new_device_report_header(HID_PROTOCOL_MOUSE);

    printf("X: %06d\tY: %06d\t|%c|%c|\r",
           x_pos, y_pos,
           (mouse_report->buttons.button1 ? 'o' : ' '),
           (mouse_report->buttons.button2 ? 'o' : ' '));
    fflush(stdout);
}

/**
 * @brief USB HID Host event callback. Handle such event as device connection and removing
 *
 * @param[in] event  HID device event
 * @param[in] arg    Pointer to arguments, does not used
 */
static void hid_host_event_callback(const hid_host_event_t *event, void *arg)
{
    if (event->event == HID_DEVICE_CONNECTED) {
        // Obtained USB device address is placed after application events
        xEventGroupSetBits(usb_flags, DEVICE_CONNECTED | (event->device.address << 4));
    } else if (event->event == HID_DEVICE_DISCONNECTED) {
        xEventGroupSetBits(usb_flags, DEVICE_DISCONNECTED);
    }
}

/**
 * @brief USB HID Host interface callback
 *
 * @param[in] event  HID interface event
 * @param[in] arg    Pointer to arguments, does not used
 */
static void hid_host_interface_event_callback(const hid_host_interface_event_t *event, void *arg)
{
    switch (event->event) {
    case HID_DEVICE_INTERFACE_INIT:
        ESP_LOGI(TAG, "Interface number %d, protocol %s",
                 event->interface.num,
                 (event->interface.proto == HID_PROTOCOL_KEYBOARD)
                 ? "Keyboard"
                 : "Mouse");

        if (event->interface.proto == HID_PROTOCOL_KEYBOARD) {
            const hid_host_interface_config_t hid_keyboard_config = {
                .proto = HID_PROTOCOL_KEYBOARD,
                .callback = hid_host_keyboard_report_callback,
            };

            hid_host_claim_interface(&hid_keyboard_config, &keyboard_handle);
        }

        if (event->interface.proto == HID_PROTOCOL_MOUSE) {
            const hid_host_interface_config_t hid_mouse_config = {
                .proto = HID_PROTOCOL_MOUSE,
                .callback = hid_host_mouse_report_callback,
            };

            hid_host_claim_interface(&hid_mouse_config, &mouse_handle);
        }

        break;
    case HID_DEVICE_INTERFACE_TRANSFER_ERROR:
        ESP_LOGD(TAG, "Interface number %d, transfer error",
                 event->interface.num);
        break;

    case HID_DEVICE_INTERFACE_CLAIM:
    case HID_DEVICE_INTERFACE_RELEASE:
        // ... do nothing here for now
        break;

    default:
        ESP_LOGI(TAG, "%s Unhandled event %X, Interface number %d",
                 __FUNCTION__,
                 event->event,
                 event->interface.num);
        break;
    }
}

/**
 * @brief Handle common USB host library events
 *
 * @param[in] args  Pointer to arguments, does not used
 */
static void handle_usb_events(void *args)
{
    while (1) {
        uint32_t event_flags;
        usb_host_lib_handle_events(portMAX_DELAY, &event_flags);

        // Release devices once all clients has deregistered
        if (event_flags & USB_HOST_LIB_EVENT_FLAGS_NO_CLIENTS) {
            usb_host_device_free_all();
            xEventGroupSetBits(usb_flags, HOST_NO_CLIENT);
        }
        // Give ready_to_uninstall_usb semaphore to indicate that USB Host library
        // can be deinitialized, and terminate this task.
        if (event_flags & USB_HOST_LIB_EVENT_FLAGS_ALL_FREE) {
            xEventGroupSetBits(usb_flags, HOST_ALL_FREE);
        }
    }

    vTaskDelete(NULL);
}

static bool wait_for_event(EventBits_t event, TickType_t timeout)
{
    return xEventGroupWaitBits(usb_flags, event, pdTRUE, pdTRUE, timeout) & event;
}

void app_main(void)
{
    TaskHandle_t usb_events_task_handle;
    hid_host_device_handle_t hid_device;

    BaseType_t task_created;

    const gpio_config_t input_pin = {
        .pin_bit_mask = BIT64(APP_QUIT_PIN),
        .mode = GPIO_MODE_INPUT,
        .pull_up_en = GPIO_PULLUP_ENABLE,
    };
    ESP_ERROR_CHECK( gpio_config(&input_pin) );

    ESP_LOGI(TAG, "HID HOST example");

    usb_flags = xEventGroupCreate();
    assert(usb_flags);

    const usb_host_config_t host_config = {
        .skip_phy_setup = false,
        .intr_flags = ESP_INTR_FLAG_LEVEL1
    };

    ESP_ERROR_CHECK( usb_host_install(&host_config) );
    task_created = xTaskCreate(handle_usb_events, "usb_events", 4096, NULL, 2, &usb_events_task_handle);
    assert(task_created);

    // hid host driver config
    const hid_host_driver_config_t hid_host_config = {
        .create_background_task = true,
        .task_priority = 5,
        .stack_size = 4096,
        .core_id = 0,
        .callback = hid_host_event_callback,
        .callback_arg = NULL
    };

    ESP_ERROR_CHECK( hid_host_install(&hid_host_config) );

    do {
        EventBits_t event = xEventGroupWaitBits(usb_flags, USB_EVENTS_TO_WAIT, pdTRUE, pdFALSE, pdMS_TO_TICKS(APP_QUIT_PIN_POLL_MS));

        if (event & DEVICE_CONNECTED) {
            xEventGroupClearBits(usb_flags, DEVICE_CONNECTED);
            hid_device_connected = true;
        }

        if (event & DEVICE_ADDRESS_MASK) {
            xEventGroupClearBits(usb_flags, DEVICE_ADDRESS_MASK);

            const hid_host_device_config_t hid_host_device_config = {
                .dev_addr = (event & DEVICE_ADDRESS_MASK) >> 4,
                        .iface_event_cb = hid_host_interface_event_callback,
                        .iface_event_arg = NULL,
            };

            ESP_ERROR_CHECK( hid_host_install_device(&hid_host_device_config, &hid_device) );
        }

        if (event & DEVICE_DISCONNECTED) {
            xEventGroupClearBits(usb_flags, DEVICE_DISCONNECTED);

            hid_host_release_interface(keyboard_handle);
            hid_host_release_interface(mouse_handle);

            ESP_ERROR_CHECK( hid_host_uninstall_device(hid_device) );

            hid_device_connected = false;
        }

    } while (gpio_get_level(APP_QUIT_PIN) != 0);

    if (hid_device_connected) {
        ESP_LOGI(TAG, "Uninitializing HID Device");
        hid_host_release_interface(keyboard_handle);
        hid_host_release_interface(mouse_handle);
        ESP_ERROR_CHECK( hid_host_uninstall_device(hid_device) );
        hid_device_connected = false;
    }

    ESP_LOGI(TAG, "Uninitializing USB");
    ESP_ERROR_CHECK( hid_host_uninstall() );
    wait_for_event(READY_TO_UNINSTALL, portMAX_DELAY);
    ESP_ERROR_CHECK( usb_host_uninstall() );
    vTaskDelete(usb_events_task_handle);
    vEventGroupDelete(usb_flags);
    ESP_LOGI(TAG, "Done");
}