/*
   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/
#include <string.h>
#include <freertos/FreeRTOS.h>
#include <freertos/task.h>
#include <freertos/event_groups.h>
#include <esp_wifi.h>
#include <esp_event.h>
#include <esp_log.h>
#include <esp_idf_version.h>
#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 1, 0)
// Features supported in 4.1+
#define ESP_NETIF_SUPPORTED
#endif

#ifdef ESP_NETIF_SUPPORTED
#include <esp_netif.h>
#else
#include <tcpip_adapter.h>
#endif

#include <wifi_provisioning/manager.h>
#ifdef CONFIG_APP_WIFI_PROV_TRANSPORT_BLE
#include <wifi_provisioning/scheme_ble.h>
#else /* CONFIG_APP_WIFI_PROV_TRANSPORT_SOFTAP */
#include <wifi_provisioning/scheme_softap.h>
#endif /* CONFIG_APP_WIFI_PROV_TRANSPORT_BLE */

#include <qrcode.h>
#include <nvs.h>
#include <nvs_flash.h>
#include "app_wifi.h"

static const char *TAG = "app_wifi";
static const int WIFI_CONNECTED_EVENT = BIT0;
static EventGroupHandle_t wifi_event_group;

#define PROV_QR_VERSION "v1"

#define PROV_TRANSPORT_SOFTAP   "softap"
#define PROV_TRANSPORT_BLE      "ble"
#define QRCODE_BASE_URL     "https://espressif.github.io/esp-jumpstart/qrcode.html"

#define CREDENTIALS_NAMESPACE   "creds"
#define RANDOM_NVS_KEY          "random"

static void app_wifi_print_qr(const char *name, const char *pop, const char *transport)
{
    if (!name || !pop || !transport) {
        ESP_LOGW(TAG, "Cannot generate QR code payload. Data missing.");
        return;
    }
    char payload[150];
    snprintf(payload, sizeof(payload), "{\"ver\":\"%s\",\"name\":\"%s\"" \
                    ",\"pop\":\"%s\",\"transport\":\"%s\"}",
                    PROV_QR_VERSION, name, pop, transport);
#ifdef CONFIG_APP_WIFI_PROV_SHOW_QR
    ESP_LOGI(TAG, "Scan this QR code from the phone app for Provisioning.");
    qrcode_display(payload);
#endif /* CONFIG_APP_WIFI_PROV_SHOW_QR */
    ESP_LOGI(TAG, "If QR code is not visible, copy paste the below URL in a browser.\n%s?data=%s", QRCODE_BASE_URL, payload);
}

/* Event handler for catching system events */
static void event_handler(void* arg, esp_event_base_t event_base,
                          long int event_id, void* event_data)
{
    if (event_base == WIFI_PROV_EVENT) {
        switch (event_id) {
            case WIFI_PROV_START:
                ESP_LOGI(TAG, "Provisioning started");
                break;
            case WIFI_PROV_CRED_RECV: {
                wifi_sta_config_t *wifi_sta_cfg = (wifi_sta_config_t *)event_data;
                ESP_LOGI(TAG, "Received Wi-Fi credentials"
                         "\n\tSSID     : %s\n\tPassword : %s",
                         (const char *) wifi_sta_cfg->ssid,
                         (const char *) wifi_sta_cfg->password);
                break;
            }
            case WIFI_PROV_CRED_FAIL: {
                wifi_prov_sta_fail_reason_t *reason = (wifi_prov_sta_fail_reason_t *)event_data;
                ESP_LOGE(TAG, "Provisioning failed!\n\tReason : %s"
                         "\n\tPlease reset to factory and retry provisioning",
                         (*reason == WIFI_PROV_STA_AUTH_ERROR) ?
                         "Wi-Fi station authentication failed" : "Wi-Fi access-point not found");
                break;
            }
            case WIFI_PROV_CRED_SUCCESS:
                ESP_LOGI(TAG, "Provisioning successful");
                break;
            case WIFI_PROV_END:
                /* De-initialize manager once provisioning is finished */
                wifi_prov_mgr_deinit();
                break;
            default:
                break;
        }
    } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {
        esp_wifi_connect();
    } else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {
        ip_event_got_ip_t* event = (ip_event_got_ip_t*) event_data;
        ESP_LOGI(TAG, "Connected with IP Address:" IPSTR, IP2STR(&event->ip_info.ip));
        /* Signal main application to continue execution */
        xEventGroupSetBits(wifi_event_group, WIFI_CONNECTED_EVENT);
    } else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {
        ESP_LOGI(TAG, "Disconnected. Connecting to the AP again...");
        esp_wifi_connect();
    }
}

static void wifi_init_sta()
{
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
    ESP_ERROR_CHECK(esp_wifi_start());
}

/* free the return value after use. */
static esp_err_t read_random_bytes_from_nvs(uint8_t **random_bytes, size_t *len)
{
    nvs_handle handle;
    esp_err_t err;
    *len = 0;

    if ((err = nvs_open_from_partition("PARTITION_NAME", CREDENTIALS_NAMESPACE,
                                NVS_READONLY, &handle)) != ESP_OK) {
        ESP_LOGD(TAG, "NVS open for %s %s %s failed with error %d", "PARTITION_NAME", CREDENTIALS_NAMESPACE, RANDOM_NVS_KEY, err);
        return ESP_FAIL;
    }

    if ((err = nvs_get_blob(handle, RANDOM_NVS_KEY, NULL, len)) != ESP_OK) {
        ESP_LOGD(TAG, "Error %d. Failed to read key %s.", err, RANDOM_NVS_KEY);
        nvs_close(handle);
        return ESP_ERR_NOT_FOUND;
    }

    *random_bytes = calloc(*len, 1);
    if (*random_bytes) {
        nvs_get_blob(handle, RANDOM_NVS_KEY, *random_bytes, len);
        nvs_close(handle);
        return ESP_OK;
    }
    nvs_close(handle);
    return ESP_ERR_NO_MEM;
}

static esp_err_t get_device_service_name(char *service_name, size_t max)
{
    uint8_t *nvs_random;
    const char *ssid_prefix = "PROV_";
    size_t nvs_random_size = 0;
    if ((read_random_bytes_from_nvs(&nvs_random, &nvs_random_size) != ESP_OK) || nvs_random_size < 3) {
        uint8_t eth_mac[6];
        esp_wifi_get_mac(WIFI_IF_STA, eth_mac);
        snprintf(service_name, max, "%s%02x%02x%02x", ssid_prefix, eth_mac[3], eth_mac[4], eth_mac[5]);
    } else {
        snprintf(service_name, max, "%s%02x%02x%02x", ssid_prefix, nvs_random[nvs_random_size - 3],
                nvs_random[nvs_random_size - 2], nvs_random[nvs_random_size - 1]);
    }
    if (nvs_random) {
        // free(nvs_random);
    }
    return ESP_OK;
}


static esp_err_t get_device_pop(char *pop, size_t max, app_wifi_pop_type_t pop_type)
{
    if (!pop || !max) {
        return ESP_ERR_INVALID_ARG;
    }

    if (pop_type == POP_TYPE_MAC) {
        uint8_t eth_mac[6];
        esp_err_t err = esp_wifi_get_mac(WIFI_IF_STA, eth_mac);
        if (err == ESP_OK) {
            snprintf(pop, max, "%02x%02x%02x%02x", eth_mac[2], eth_mac[3], eth_mac[4], eth_mac[5]);
            return ESP_OK;
        } else {
            return err;
        }
    } else if (pop_type == POP_TYPE_RANDOM) {
        uint8_t *nvs_random;
        size_t nvs_random_size = 0;
        if ((read_random_bytes_from_nvs(&nvs_random, &nvs_random_size) != ESP_OK) || nvs_random_size < 4) {
            return ESP_ERR_NOT_FOUND;
        } else {
            snprintf(pop, max, "%02x%02x%02x%02x", nvs_random[0], nvs_random[1], nvs_random[2], nvs_random[3]);
            free(nvs_random);
            return ESP_OK;
        }
    } else {
        return ESP_ERR_INVALID_ARG;
    }
}

void app_wifi_init(void)
{
    /* Initialize TCP/IP */
#ifdef ESP_NETIF_SUPPORTED
    esp_netif_init();
#else
    tcpip_adapter_init();
#endif

    /* Initialize the event loop */
    //ESP_ERROR_CHECK(esp_event_loop_create_default());
    wifi_event_group = xEventGroupCreate();

    /* Register our event handler for Wi-Fi, IP and Provisioning related events */
    ESP_ERROR_CHECK(esp_event_handler_register(WIFI_PROV_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL));
    ESP_ERROR_CHECK(esp_event_handler_register(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL));
    ESP_ERROR_CHECK(esp_event_handler_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL));

    /* Initialize Wi-Fi including netif with default config */
#ifdef ESP_NETIF_SUPPORTED
    esp_netif_create_default_wifi_sta();
#endif
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
}

esp_err_t app_wifi_start(app_wifi_pop_type_t pop_type)
{
    /* Configuration for the provisioning manager */
    wifi_prov_mgr_config_t config = {
        /* What is the Provisioning Scheme that we want ?
         * wifi_prov_scheme_softap or wifi_prov_scheme_ble */
#ifdef CONFIG_APP_WIFI_PROV_TRANSPORT_BLE
        .scheme = wifi_prov_scheme_ble,
#else /* CONFIG_APP_WIFI_PROV_TRANSPORT_SOFTAP */
        .scheme = wifi_prov_scheme_softap,
#endif /* CONFIG_APP_WIFI_PROV_TRANSPORT_BLE */

        /* Any default scheme specific event handler that you would
         * like to choose. Since our example application requires
         * neither BT nor BLE, we can choose to release the associated
         * memory once provisioning is complete, or not needed
         * (in case when device is already provisioned). Choosing
         * appropriate scheme specific event handler allows the manager
         * to take care of this automatically. This can be set to
         * WIFI_PROV_EVENT_HANDLER_NONE when using wifi_prov_scheme_softap*/
#ifdef CONFIG_APP_WIFI_PROV_TRANSPORT_BLE
        .scheme_event_handler = WIFI_PROV_SCHEME_BLE_EVENT_HANDLER_FREE_BTDM
#else /* CONFIG_APP_WIFI_PROV_TRANSPORT_SOFTAP */
        .scheme_event_handler = WIFI_PROV_EVENT_HANDLER_NONE,
#endif /* CONFIG_APP_WIFI_PROV_TRANSPORT_BLE */
    };

    /* Initialize provisioning manager with the
     * configuration parameters set above */
    ESP_ERROR_CHECK(wifi_prov_mgr_init(config));

    bool provisioned = false;
    /* Let's find out if the device is provisioned */
    ESP_ERROR_CHECK(wifi_prov_mgr_is_provisioned(&provisioned));

    /* If device is not yet provisioned start provisioning service */
    if (!provisioned) {
        ESP_LOGI(TAG, "Starting provisioning");
#ifdef ESP_NETIF_SUPPORTED
        esp_netif_create_default_wifi_ap();
#endif

        /* What is the Device Service Name that we want
         * This translates to :
         *     - Wi-Fi SSID when scheme is wifi_prov_scheme_softap
         *     - device name when scheme is wifi_prov_scheme_ble
         */
        char service_name[12];
        get_device_service_name(service_name, sizeof(service_name));

        /* What is the security level that we want (0 or 1):
         *      - WIFI_PROV_SECURITY_0 is simply plain text communication.
         *      - WIFI_PROV_SECURITY_1 is secure communication which consists of secure handshake
         *          using X25519 key exchange and proof of possession (pop) and AES-CTR
         *          for encryption/decryption of messages.
         */
        wifi_prov_security_t security = WIFI_PROV_SECURITY_1;

        /* Do we want a proof-of-possession (ignored if Security 0 is selected):
         *      - this should be a string with length > 0
         *      - NULL if not used
         */
        char pop[9];
        esp_err_t err = get_device_pop(pop, sizeof(pop), pop_type);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "Error: %d. Failed to get PoP from NVS, Please perform Claiming.", err);
            return err;
        }

        /* What is the service key (Wi-Fi password)
         * NULL = Open network
         * This is ignored when scheme is wifi_prov_scheme_ble
         */
        const char *service_key = NULL;

#ifdef CONFIG_APP_WIFI_PROV_TRANSPORT_BLE
        /* This step is only useful when scheme is wifi_prov_scheme_ble. This will
         * set a custom 128 bit UUID which will be included in the BLE advertisement
         * and will correspond to the primary GATT service that provides provisioning
         * endpoints as GATT characteristics. Each GATT characteristic will be
         * formed using the primary service UUID as base, with different auto assigned
         * 12th and 13th bytes (assume counting starts from 0th byte). The client side
         * applications must identify the endpoints by reading the User Characteristic
         * Description descriptor (0x2901) for each characteristic, which contains the
         * endpoint name of the characteristic */
        uint8_t custom_service_uuid[] = {
            /* This is a random uuid. This can be modified if you want to change the BLE uuid. */
            /* 12th and 13th bit will be replaced by internal bits. */
            0xb4, 0xdf, 0x5a, 0x1c, 0x3f, 0x6b, 0xf4, 0xbf,
            0xea, 0x4a, 0x82, 0x03, 0x04, 0x90, 0x1a, 0x02,
        };
        err = wifi_prov_scheme_ble_set_service_uuid(custom_service_uuid);
        if (err != ESP_OK) {
            ESP_LOGE(TAG, "wifi_prov_scheme_ble_set_service_uuid failed %d", err);
            return err;
        }
#endif /* CONFIG_APP_WIFI_PROV_TRANSPORT_BLE */

        /* Start provisioning service */
        ESP_ERROR_CHECK(wifi_prov_mgr_start_provisioning(security, pop, service_name, service_key));
        /* Print QR code for provisioning */
#ifdef CONFIG_APP_WIFI_PROV_TRANSPORT_BLE
        app_wifi_print_qr(service_name, pop, PROV_TRANSPORT_BLE);
#else /* CONFIG_APP_WIFI_PROV_TRANSPORT_SOFTAP */
        app_wifi_print_qr(service_name, pop, PROV_TRANSPORT_SOFTAP);
#endif /* CONFIG_APP_WIFI_PROV_TRANSPORT_BLE */
        ESP_LOGI(TAG, "Provisioning Started. Name : %s, POP : %s", service_name, pop);
    } else {
        ESP_LOGI(TAG, "Already provisioned, starting Wi-Fi STA");

        /* We don't need the manager as device is already provisioned,
         * so let's release it's resources */
        wifi_prov_mgr_deinit();

        /* Start Wi-Fi station */
        wifi_init_sta();
    }
    /* Wait for Wi-Fi connection */
    vWaitOnWifiConnected();
    return ESP_OK;
}

void vWaitOnWifiConnected( void )
{
    xEventGroupWaitBits(wifi_event_group, WIFI_CONNECTED_EVENT, false, true, portMAX_DELAY);
}