/* Simple FTP-like protocol, used both for command line and
 * server communication.
 */

#include "cmd_base.h"
#include "cmd_list.h"
#include "syslog.h"

#include <stdbool.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdarg.h>
#include <ctype.h>
#include <limits.h>

// Delimiters for command arguments.
static const char delim[] = " \t\n";

/* Utility functions for reading command arguments inside command handlers.
 * Return false on invalid value.
 */

bool cmd_string_arg(cmdargs_t *args, char **dest)
{
    *dest = strtok_r(NULL, delim, &args->saveptr);
    return (*dest != NULL && **dest != '\0');
}

bool cmd_signed_arg(cmdargs_t *args, signed *dest)
{
    char *arg = strtok_r(NULL, delim, &args->saveptr);
    char *endptr;
    
    if (arg == NULL || *arg == '\0')
            return false;
    
    *dest = strtol(arg, &endptr, 0);
    
    return *endptr == '\0';
}

bool cmd_unsigned_arg(cmdargs_t *args, unsigned *dest)
{
    char *arg = strtok_r(NULL, delim, &args->saveptr);
    char *endptr;
    
    if (arg == NULL || *arg == '\0')
            return false;
    
    *dest = strtoul(arg, &endptr, 0);
    
    return *endptr == '\0';
}

/* Check that all arguments have been read. */
bool cmd_last_arg(cmdargs_t *args)
{
    return strtok_r(NULL, delim, &args->saveptr) == NULL;
}

/* Utility function for returning replies.
 * Example usage: set_result(args, 200, "OK");
 */
void cmd_result(cmdargs_t *args, int status, const char *info)
{
    args->status = status;
    fprintf(args->out, "%d %s\n", status, info);
}

void cmd_resultf(cmdargs_t *args, int status, const char *info, ...)
{
    args->status = status;
    va_list va;
    va_start(va, info);
    fprintf(args->out, "%d ", status);
    vfprintf(args->out, info, va);
    fprintf(args->out, "\n");
    va_end(va);
}

/* Single command execution.
 * Note: this function modifies the contents of cmdline.
 */
void cmd_run(cmdargs_t *args, char *cmdline)
{
    args->saveptr = NULL;
    args->status = 0;
    args->cmd = strtok_r(cmdline, delim, &args->saveptr);
    
    if (args->cmd == NULL) // Empty command
    {
        cmd_result(args, 200, "OK");
        return;
    }
    
    bool status = false;
    for (int i = 0; i < COMMANDS_COUNT; i++) 
    {
        if (strcasecmp(COMMANDS[i].cmd, args->cmd) == 0)
        {
            status = COMMANDS[i].handler(args);
            
            if (!status)
            {
                cmd_resultf(args, 214, "usage: %s %s\n", COMMANDS[i].cmd, COMMANDS[i].help);
                status = true;
            }
            
            break;
        }
    }
    
    if (!status) {
        cmd_result(args, 502, "Unknown command");
    }
    
    syslog("cmd status %d", args->status, 0);
}


/* Continuous chat with a bi-directional stream.
 * Returns when connection is closed with a command or a read timeouts.
 */

void cmd_chat(FILE *stream, int cmdbuf_size)
{
    char *cmdbuf = malloc(cmdbuf_size);
    cmdargs_t args = {0};
    args.in = args.out = stream;
    
    for(;;)
    {
        if (!fgets(cmdbuf, cmdbuf_size, stream))
            break; // EOF or timeout
        
        if (cmdbuf[strlen(cmdbuf) - 1] != '\n')
        {
            cmd_result(&args, 500, "Command line too long");
            continue;
        }
        
        cmd_run(&args, cmdbuf);
        
        if (args.status == 221)
            break; // Closing connection
    }
    
    free(cmdbuf);
}