/**
 * @file tftp.c
 * @brief tftp server
 * @author Speetjens S.
 */

#include "tftp.h"

static const char* TAG = "tftp_server";

extern struct llfs_data_file* llfs_root;

static llfs_file_t virt_file[2] = {
    {.name = "index.txt", .data = "test", .len = 4},
    {.name = "virtImage.raw", .data = "test", .len = 4}
    };

int str_cat_str(char* dest, int dest_size, const char* src) {
    int dest_len = strlen(dest);
    int src_len = strlen(src);
    if (dest_len + src_len > dest_size) {
        return -1;
    }
    memcpy(dest + dest_len, src, src_len);
    return 0;
}

int str_cat(char* dest, int dest_size, char c)
{
    int dest_len = strlen(dest);
    if (dest_len + 1 > dest_size) {
        return -1;
    }
    dest[dest_len] = c;
    dest[dest_len + 1] = '\0';
    return 0;
}

/**
 * @brief tftp helper functions
 */

/**
 * @brief This function is called when a file is opened
 *        It should return a handle to the file or NULL if the file does not exist
 *        The handle contains a ptr to or the actual file data or a virtual file
 * 
 * @param fname The name of the file to open
 * @param mode 	Mode string from TFTP RFC
 * @param write Flag indicating read (0) or write (!= 0) access
 * @return void* File handle supplied to other functions 
 */
void* tftp_open(const char* fname, const char* mode, u8_t write) {
    LOG_INFO(TAG, "Opening %s", fname);

    if (strcmp(fname, virt_file[0].name) == 0 && write == TFTP_READ) {
        return &virt_file[0];
    } else if (strcmp(fname, virt_file[1].name) == 0 && write != TFTP_READ) {
        return &virt_file[1];
    }

    // TODO: waiting on Lorentz to finish creating f* functions for LLFS
    return fopen(fname, write ? "wb" : "rb");
}

/**
 * @brief This function is called when a file is closed
 * 
 * @param handle The handle to the file to close
 */
void tftp_close(void* handle) {
    LOG_INFO(TAG, "closing file");
    if (handle == NULL) {
        LOG_CRIT(TAG, "handle is null");
        return;
    }
    if (handle == &virt_file[0] || handle == &virt_file[1]) {
        return;
    }

    // TODO: waiting on Lorentz to finish creating f* functions for LLFS
    fclose((FILE*)handle);
}

/**
 * @brief This function is called when a file is read
 *        The virtual files are filtered out first
 *        then the file is trying to get read from the llfs
 * 
 * @param handle File handle returned by open()
 * @param buf Target buffer to copy read data to 
 * @param bytes Number of bytes to copy to buf 
 * @return int >= 0: Success; < 0: Error 
 */
int tftp_read(void* handle, void* buf, int bytes) {
    LOG_INFO(TAG, "reading file");
    if (handle == NULL) {
        LOG_CRIT(TAG, "handle is null");
        return -1;
    }
    FILE* file = (FILE*)handle;
    LOG_INFO(TAG, "reading file: %s", file->name);

    if (file == &virt_file[0]) {
        const struct llfs_data_file* root = llfs_root;
        str_cat_str(buf, bytes, virt_file[0].name);
        str_cat(buf, bytes, '\n');
        str_cat_str(buf, bytes, virt_file[1].name);
        str_cat(buf, bytes, '\n');
        while(root != NULL) {
            str_cat(buf, bytes, root->name);
            str_cat(buf, bytes, '\n');
            file = root->next;
        }
    } else if (file == &virt_file[1]) {
        LOG_CRIT(TAG, "Exception: Trying to read a write only file");
        return -1;
    }
    // TODO: waiting on Lorentz to finish creating f* functions for LLFS
    fread(buf, sizeof(uint8_t), bytes, file);
    return 0;
}

/**
 * @brief This function is called when a file is written
 * 
 * @param handle File handle returned by open()
 * @param p PBUF adjusted such that payload pointer points to the beginning of write data.
 * In other words, TFTP headers are stripped off. 
 * @return int >= 0: Success; < 0: Error 
 */
int tftp_write(void* handle, struct pbuf* p) {
    LOG_INFO(TAG, "Writing file");
    LOG_DEBUG(TAG, "Not implemented yet");
}

struct tftp_context tftpContext_s = {
    .open = tftp_open,
    .close = tftp_close,
    .read = tftp_read,
    .write = tftp_write
    };

/**
 * @brief Initialize tftp server
 */
void tftp_server_init(void) {
    LOG_INFO(TAG, "Initializing tftp server");
    if (tftp_init(&tftpContext_s) != ERR_OK) {
        LOG_FATAL(TAG, "Could not initialize tftp server");
        return;
    }
    LOG_INFO(TAG, "tftp server initialized successfully");
}