#include <device.h>
#include <drivers/flash.h>
#include <fs/nvs.h>
#include <power/reboot.h>
#include <storage/flash_map.h>
#include <string.h>
#include <zephyr.h>

#include "ens_fs.h"
#include "sequencenumber.h"
#include "storage.h"

// Maybe use this as param for init function
#define SEC_COUNT 8U

#define STORED_CONTACTS_INFO_ID 0
#define MAX_CONTACTS 65536

static struct nvs_fs info_fs;

// Information about currently stored contacts
static stored_contacts_information_t contact_information = {.oldest_contact = 0, .count = 0};

inline storage_id_t convert_sn_to_storage_id(record_sequence_number_t sn) {
    return (storage_id_t)(sn % MAX_CONTACTS);
}

/**
 * Load our initial storage information from flash.
 */
int load_storage_information() {
    size_t size = sizeof(contact_information);
    int rc = nvs_read(&info_fs, STORED_CONTACTS_INFO_ID, &contact_information, size);

    // Check, if read what we wanted
    if (rc != size) {
        // Write our initial data to storage
        rc = nvs_write(&info_fs, STORED_CONTACTS_INFO_ID, &contact_information, size);
        if (rc <= 0) {
            return rc;
        }
    }
    return 0;
}

/**
 * Save our current storage infromation to flash.
 */
int save_storage_information() {
    int rc = nvs_write(&info_fs, STORED_CONTACTS_INFO_ID, &contact_information, sizeof(contact_information));
    if (rc <= 0) {
        printk("Something went wrong after saving storage information.\n");
    }
    return rc;
}

record_sequence_number_t get_next_sequence_number() {
    if (contact_information.count >= MAX_CONTACTS) {
        contact_information.oldest_contact = sn_increment(contact_information.oldest_contact);
    } else {
        contact_information.count++;
    }
    save_storage_information();
    return get_latest_sequence_number();
}

int init_contact_storage(void) {
    int rc = 0;
    struct flash_pages_info info;
    // define the nvs file system
    info_fs.offset = FLASH_AREA_OFFSET(storage);
    rc = flash_get_page_info_by_offs(device_get_binding(DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL), info_fs.offset, &info);

    if (rc) {
        // Error during retrieval of page information
        return rc;
    }
    info_fs.sector_size = info.size;
    info_fs.sector_count = SEC_COUNT;

    rc = nvs_init(&info_fs, DT_CHOSEN_ZEPHYR_FLASH_CONTROLLER_LABEL);
    if (rc) {
        // Error during nvs_init
        return rc;
    }

    // Load the current storage information
    rc = load_storage_information();

    printk("Currently %d contacts stored!\n", contact_information.count);
    printk("Space available: %d\n", FLASH_AREA_SIZE(storage));

    return rc;
}

int load_contact(contact_t* dest, record_sequence_number_t sn) {
    storage_id_t id = convert_sn_to_storage_id(sn);
    int rc = nvs_read(&info_fs, id, dest, sizeof(*dest));
    if (rc <= 0) {
        return rc;
    }
    return 0;
}

int add_contact(contact_t* src) {
    record_sequence_number_t curr_sn = get_next_sequence_number();
    storage_id_t id = convert_sn_to_storage_id(curr_sn);

    int rc = nvs_write(&info_fs, id, src, sizeof(*src));
    if (rc > 0) {
        return 0;
    }
    return rc;
}

// TODO handle start and end
int delete_contact(record_sequence_number_t sn) {
    storage_id_t id = convert_sn_to_storage_id(sn);
    int rc = nvs_delete(&info_fs, id);
    if (!rc) {
        if (sn_equal(sn, get_latest_sequence_number())) {
            contact_information.count--;
        } else if (sn_equal(sn, get_oldest_sequence_number())) {
            contact_information.oldest_contact = sn_increment(contact_information.oldest_contact);
            contact_information.count--;
        }
        save_storage_information();
    }
    return rc;
}

record_sequence_number_t get_latest_sequence_number() {
    return sn_mask(contact_information.oldest_contact + contact_information.count);
}

record_sequence_number_t get_oldest_sequence_number() {
    return contact_information.oldest_contact;
}

uint32_t get_num_contacts() {
    return contact_information.count;
}