#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>
#include <zephyr/shell/shell.h>
#include <zephyr/sys/reboot.h>
#include <zephyr/settings/settings.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <lasertag_utils.h>
#include <stdio.h>

LOG_MODULE_REGISTER(lt_utils, CONFIG_LASERTAG_UTILS_LOG_LEVEL);

static char device_name[32] = "Eriks Lasertag Device";

/* --- Settings Handler --- */

static int lasertag_settings_set(const char *name, size_t len, settings_read_cb read_cb, void *cb_arg)
{
    const char *next;
    if (settings_name_steq(name, "name", &next) && !next)
    {
        if (len > sizeof(device_name) - 1)
            return -EINVAL;
        ssize_t rc = read_cb(cb_arg, device_name, len);
        if (rc >= 0)
        {
            device_name[rc] = '\0';
            return 0;
        }
    }
    return -ENOENT;
}

struct settings_handler lasertag_conf = {.name = "lasertag", .h_set = lasertag_settings_set};

void lasertag_utils_init(void)
{
    settings_subsys_init();
    settings_register(&lasertag_conf);
    settings_load();
}

/* Getters */
const char *lasertag_get_device_name(void) { return device_name; }

/* Setters */
int lasertag_set_device_name(const char *name, size_t len)
{
    if (len >= sizeof(device_name))
        len = sizeof(device_name) - 1;
    memcpy(device_name, name, len);
    device_name[len] = '\0';
    return settings_save_one("lasertag/name", device_name, len);
}

/* --- Watchdog --- */
#ifdef CONFIG_WATCHDOG
#include <zephyr/drivers/watchdog.h>
#include <zephyr/logging/log_ctrl.h>

#define WDT_NODE DT_ALIAS(watchdog0)

static int wdt_channel_id;
static const struct device *wdt = DEVICE_DT_GET(WDT_NODE);

int lasertag_init_watchdog(void)
{
    struct wdt_timeout_cfg wdt_config = {
        .window.min = 0U,
        .window.max = CONFIG_LASERTAG_UTILS_WD_TIMEOUT,
        .flags = WDT_FLAG_RESET_SOC,
    };

    if (!device_is_ready(wdt)) {
        LOG_ERR("Watchdog device is not ready");
        return -ENODEV;
    }
    
    wdt_channel_id = wdt_install_timeout(wdt, &wdt_config);
    if (wdt_channel_id == -EBUSY) {
        wdt_channel_id = 0;
        LOG_WRN("Watchdog already running, using channel %d", wdt_channel_id);
        return 0;
    }
    if (wdt_channel_id < 0) {
        LOG_ERR("Failed to install watchdog timeout");
        return wdt_channel_id;
    }
    
    int rc = wdt_setup(wdt, 0);
    if (rc < 0) {
        LOG_ERR("Failed to setup watchdog");
        return rc;
    }

    LOG_DBG("Watchdog '%s' initialized channel %d with a %d ms timeout", wdt->name, wdt_channel_id, CONFIG_LASERTAG_UTILS_WD_TIMEOUT);
    return 0;
}

void lasertag_feed_watchdog(void)
{
    int rc = wdt_feed(wdt, wdt_channel_id);
    if (rc < 0) {
        LOG_ERR("Failed to feed watchdog, error code: %d", rc);
    } else {
        LOG_DBG("Watchdog '%s' fed successfully", wdt->name);
    }
}
#endif /* CONFIG_WATCHDOG */


/* --- Utility Functions --- */

/* CRC8 CCITT polynome lookup table (polynome: 0x07, initial: 0x00) */
static const uint8_t crc8_table[256] = {
    0x00, 0x07, 0x0E, 0x09, 0x1C, 0x1B, 0x12, 0x15, 0x38, 0x3F, 0x36, 0x31, 0x24, 0x23, 0x2A, 0x2D,
    0x70, 0x77, 0x7E, 0x79, 0x6C, 0x6B, 0x62, 0x65, 0x48, 0x4F, 0x46, 0x41, 0x54, 0x53, 0x5A, 0x5D,
    0xE0, 0xE7, 0xEE, 0xE9, 0xFC, 0xFB, 0xF2, 0xF5, 0xD8, 0xDF, 0xD6, 0xD1, 0xC4, 0xC3, 0xCA, 0xCD,
    0x90, 0x97, 0x9E, 0x99, 0x8C, 0x8B, 0x82, 0x85, 0xA8, 0xAF, 0xA6, 0xA1, 0xB4, 0xB3, 0xBA, 0xBD,
    0xC7, 0xC0, 0xC9, 0xCE, 0xDB, 0xDC, 0xD5, 0xD2, 0xFF, 0xF8, 0xF1, 0xF6, 0xE3, 0xE4, 0xED, 0xEA,
    0xB7, 0xB0, 0xB9, 0xBE, 0xAB, 0xAC, 0xA5, 0xA2, 0x8F, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9D, 0x9A,
    0x27, 0x20, 0x29, 0x2E, 0x3B, 0x3C, 0x35, 0x32, 0x1F, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0D, 0x0A,
    0x57, 0x50, 0x59, 0x5E, 0x4B, 0x4C, 0x45, 0x42, 0x6F, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7D, 0x7A,
    0x89, 0x8E, 0x87, 0x80, 0x95, 0x92, 0x9B, 0x9C, 0xB1, 0xB6, 0xBF, 0xB8, 0xAD, 0xAA, 0xA3, 0xA4,
    0xF9, 0xFE, 0xF7, 0xF0, 0xE5, 0xE2, 0xEB, 0xEC, 0xC1, 0xC6, 0xCF, 0xC8, 0xDD, 0xDA, 0xD3, 0xD4,
    0x69, 0x6E, 0x67, 0x60, 0x75, 0x72, 0x7B, 0x7C, 0x51, 0x56, 0x5F, 0x58, 0x4D, 0x4A, 0x43, 0x44,
    0x19, 0x1E, 0x17, 0x10, 0x05, 0x02, 0x0B, 0x0C, 0x21, 0x26, 0x2F, 0x28, 0x3D, 0x3A, 0x33, 0x34,
    0x4E, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5C, 0x5B, 0x76, 0x71, 0x78, 0x7F, 0x6A, 0x6D, 0x64, 0x63,
    0x3E, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2C, 0x2B, 0x06, 0x01, 0x08, 0x0F, 0x1A, 0x1D, 0x14, 0x13,
    0xAE, 0xA9, 0xA0, 0xA7, 0xB2, 0xB5, 0xBC, 0xBB, 0x96, 0x91, 0x98, 0x9F, 0x8A, 0x8D, 0x84, 0x83,
    0xDE, 0xD9, 0xD0, 0xD7, 0xC2, 0xC5, 0xCC, 0xCB, 0xE6, 0xE1, 0xE8, 0xEF, 0xFA, 0xFD, 0xF4, 0xF3
};

uint8_t lastertag_crc8(const uint8_t *data, size_t len)
{
    uint8_t crc = 0x00;
    for (size_t i = 0; i < len; i++) {
        crc = crc8_table[crc ^ data[i]];
    }
    return crc;
}