/*
hid-keyboard.c - HID Keyboard
Copyright (C) 2022  X512 <github.com/X547>

This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/

#include "i2c-hid.h"
#include "hid_api.h"
#include "spinlock.h"
#include "utils.h"
#include "bit_ops.h"
#include "mem_ops.h"

#define MAX_PRESSED_KEYS 6

static const uint8_t keyboard_hid_report_descriptor[] = {
    0x05, 0x01,     /* Usage Page (Generic Desktop) */
    0x09, 0x06,     /* Usage (Keyboard) */
    0xa1, 0x01,     /* Collection (Application) */
    0x75, 0x01,     /*   Report Size (1) */
    0x95, 0x08,     /*   Report Count (8) */
    0x05, 0x07,     /*   Usage Page (Key Codes) */
    0x19, 0xe0,     /*   Usage Minimum (224) */
    0x29, 0xe7,     /*   Usage Maximum (231) */
    0x15, 0x00,     /*   Logical Minimum (0) */
    0x25, 0x01,     /*   Logical Maximum (1) */
    0x81, 0x02,     /*   Input (Data, Variable, Absolute) */
    0x95, 0x01,     /*   Report Count (1) */
    0x75, 0x08,     /*   Report Size (8) */
    0x81, 0x01,     /*   Input (Constant) */
    0x95, 0x05,     /*   Report Count (5) */
    0x75, 0x01,     /*   Report Size (1) */
    0x05, 0x08,     /*   Usage Page (LEDs) */
    0x19, 0x01,     /*   Usage Minimum (1) */
    0x29, 0x05,     /*   Usage Maximum (5) */
    0x91, 0x02,     /*   Output (Data, Variable, Absolute) */
    0x95, 0x01,     /*   Report Count (1) */
    0x75, 0x03,     /*   Report Size (3) */
    0x91, 0x01,     /*   Output (Constant) */
    0x95, 0x06,     /*   Report Count (6) */
    0x75, 0x08,     /*   Report Size (8) */
    0x15, 0x00,     /*   Logical Minimum (0) */
    0x25, 0xff,     /*   Logical Maximum (255) */
    0x05, 0x07,     /*   Usage Page (Key Codes) */
    0x19, 0x00,     /*   Usage Minimum (0) */
    0x29, 0xff,     /*   Usage Maximum (255) */
    0x81, 0x00,     /*   Input (Data, Array) */
    0xc0,       /* End Collection */
};

struct hid_keyboard {
    hid_dev_t hid_dev;
    spinlock_t lock;

    uint8_t input_report[10];
    uint8_t output_report[3];

    // State
    uint32_t keys_pressed_now[8];
    uint32_t keys_pressed[8];
    uint32_t leds;
};

static void hid_keyboard_reset(void* dev)
{
    hid_keyboard_t* kb = dev;
    atomic_store_uint32(&kb->leds, 0);
}

static void hid_keyboard_fill_pressed_keys(hid_keyboard_t* kb, uint8_t* pressed)
{
    size_t count = 0;
    memset(pressed, HID_KEY_NONE, MAX_PRESSED_KEYS);

    for (size_t code_hi = 0; code_hi < 8; ++code_hi) {
        uint32_t keys = atomic_swap_uint32(&kb->keys_pressed[code_hi], 0)
                      | atomic_load_uint32(&kb->keys_pressed_now[code_hi]);
        if (keys) {
            for (bitcnt_t code_lo = 0; code_lo < 32; ++code_lo) {
                if (bit_check(keys, code_lo)) {
                    // Report a pressed button
                    pressed[count++] = (code_hi << 5) | code_lo;
                    if (count == MAX_PRESSED_KEYS) return;
                }
            }
        }
    }
}

static void hid_keyboard_read_report(void* dev, uint8_t report_type, uint8_t report_id,
                                     uint32_t offset, uint8_t* val)
{
    hid_keyboard_t* kb = (hid_keyboard_t*)dev;
    UNUSED(report_id);

    spin_lock(&kb->lock);
    if (report_type == REPORT_TYPE_INPUT) {
        if (offset == 0) {
            kb->input_report[0] = bit_cut(sizeof(kb->input_report), 0, 8);
            kb->input_report[1] = bit_cut(sizeof(kb->input_report), 8, 8);
            kb->input_report[2] = bit_cut(atomic_load_uint32(&kb->keys_pressed[7])
                                        | atomic_load_uint32(&kb->keys_pressed_now[7]), 0, 8);
            kb->input_report[3] = 0;
            hid_keyboard_fill_pressed_keys(kb, &kb->input_report[4]);
        }
        if (offset < sizeof(kb->input_report)) {
            *val = kb->input_report[offset];
        }
    } else {
        *val = 0;
    }
    spin_unlock(&kb->lock);
}

static void hid_keyboard_write_report(void* dev, uint8_t report_type, uint8_t report_id,
                                      uint32_t offset, uint8_t val)
{
    hid_keyboard_t* kb = (hid_keyboard_t*)dev;
    UNUSED(report_id);

    spin_lock(&kb->lock);
    if (report_type == REPORT_TYPE_OUTPUT) {
        if (offset < sizeof(kb->output_report)) {
            kb->output_report[offset] = val;
            if (offset == sizeof(kb->output_report) - 1) {
                atomic_store_uint32(&kb->leds, kb->output_report[2]);
            }
        }
    }
    spin_unlock(&kb->lock);
}

static void hid_keyboard_remove(void* dev)
{
    hid_keyboard_t* kb = dev;
    free(kb);
}

PUBLIC hid_keyboard_t* hid_keyboard_init_auto(rvvm_machine_t* machine)
{
    hid_keyboard_t* kb = safe_new_obj(hid_keyboard_t);

    kb->hid_dev.dev = kb;

    kb->hid_dev.report_desc = keyboard_hid_report_descriptor;
    kb->hid_dev.report_desc_size = sizeof(keyboard_hid_report_descriptor);
    kb->hid_dev.max_input_size = sizeof(kb->input_report);
    kb->hid_dev.max_output_size = sizeof(kb->output_report);
    kb->hid_dev.vendor_id = 1;
    kb->hid_dev.product_id = 1;
    kb->hid_dev.version_id = 1;

    kb->hid_dev.reset = hid_keyboard_reset;
    kb->hid_dev.read_report = hid_keyboard_read_report;
    kb->hid_dev.write_report = hid_keyboard_write_report;
    kb->hid_dev.remove = hid_keyboard_remove;

    i2c_hid_init_auto(machine, &kb->hid_dev);

    return kb;
}

PUBLIC void hid_keyboard_press(hid_keyboard_t* kb, hid_key_t key)
{
    // Key is guaranteed to be 1 byte according to HID spec
    if (key != HID_KEY_NONE) {
        uint32_t off = key >> 5;
        uint32_t bit = 1U << (key & 0x1F);
        uint32_t old_pressed = atomic_or_uint32(&kb->keys_pressed_now[off], bit);

        // Send input_available if it's an actual key press
        if (bit & ~old_pressed) {
            // Mark that this key was pressed, prevents loosing keypresses
            atomic_or_uint32(&kb->keys_pressed[off], bit);
            kb->hid_dev.input_available(kb->hid_dev.host, 0);
        }
    }
}

PUBLIC void hid_keyboard_release(hid_keyboard_t* kb, hid_key_t key)
{
    if (key != HID_KEY_NONE) {
        uint32_t off = key >> 5;
        uint32_t bit = 1U << (key & 0x1F);
        uint32_t old_pressed = atomic_and_uint32(&kb->keys_pressed_now[off], ~bit);

        // Send input_available if it's an actual key release
        if (old_pressed & bit) {
            kb->hid_dev.input_available(kb->hid_dev.host, 0);
        }
    }
}
