/*
    ChibiOS - Copyright (C) 2006..2016 Giovanni Di Sirio

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

/**
 * @file    shell.c
 * @brief   Simple CLI shell code.
 *
 * @addtogroup SHELL
 * @{
 */

#include <string.h>

#include "ch.h"
#include "hal.h"
#include "shell.h"
#include "shell_cmd.h"
#include "chprintf.h"

/*===========================================================================*/
/* Module local definitions.                                                 */
/*===========================================================================*/

/*===========================================================================*/
/* Module exported variables.                                                */
/*===========================================================================*/

/**
 * @brief   Shell termination event source.
 */
event_source_t shell_terminated;

/*===========================================================================*/
/* Module local types.                                                       */
/*===========================================================================*/

/*===========================================================================*/
/* Module local variables.                                                   */
/*===========================================================================*/

/*===========================================================================*/
/* Module local functions.                                                   */
/*===========================================================================*/

static char *parse_arguments(char *str, char **saveptr) {
  char *p;

  if (str != NULL)
    *saveptr = str;

  p = *saveptr;
  if (!p) {
    return NULL;
  }

  /* Skipping white space.*/
  p += strspn(p, " \t");

  if (*p == '"') {
    /* If an argument starts with a double quote then its delimiter is another
       quote.*/
    p++;
    *saveptr = strpbrk(p, "\"");
  }
  else {
    /* The delimiter is white space.*/
    *saveptr = strpbrk(p, " \t");
  }

  /* Replacing the delimiter with a zero.*/
  if (*saveptr != NULL) {
    *(*saveptr)++ = '\0';
  }

  return *p != '\0' ? p : NULL;
}

static void usage(BaseSequentialStream *chp, char *p) {

  chprintf(chp, "Usage: %s\r\n", p);
}

static void list_commands(BaseSequentialStream *chp, const ShellCommand *scp) {

  while (scp->sc_name != NULL) {
    chprintf(chp, "%s ", scp->sc_name);
    scp++;
  }
}

static bool cmdexec(const ShellCommand *scp, BaseSequentialStream *chp,
                      char *name, int argc, char *argv[]) {

  while (scp->sc_name != NULL) {
    if (strcmp(scp->sc_name, name) == 0) {
      scp->sc_function(chp, argc, argv);
      return false;
    }
    scp++;
  }
  return true;
}

/*===========================================================================*/
/* Module exported functions.                                                */
/*===========================================================================*/

/**
 * @brief   Shell thread function.
 *
 * @param[in] p         pointer to a @p BaseSequentialStream object
 */
THD_FUNCTION(shellThread, p) {
  int n;
  BaseSequentialStream *chp = ((ShellConfig *)p)->sc_channel;
  const ShellCommand *scp = ((ShellConfig *)p)->sc_commands;
  char *lp, *cmd, *tokp, line[SHELL_MAX_LINE_LENGTH];
  char *args[SHELL_MAX_ARGUMENTS + 1];

  chprintf(chp, "\r\nChibiOS/RT Shell\r\n");
  while (true) {
    chprintf(chp, "ch> ");
    if (shellGetLine(chp, line, sizeof(line))) {
      chprintf(chp, "\r\nlogout");
      break;
    }
    lp = parse_arguments(line, &tokp);
    cmd = lp;
    n = 0;
    while ((lp = parse_arguments(NULL, &tokp)) != NULL) {
      if (n >= SHELL_MAX_ARGUMENTS) {
        chprintf(chp, "too many arguments\r\n");
        cmd = NULL;
        break;
      }
      args[n++] = lp;
    }
    args[n] = NULL;
    if (cmd != NULL) {
      if (strcmp(cmd, "exit") == 0) {
        if (n > 0) {
          usage(chp, "exit");
          continue;
        }
        break;
      }
      else if (strcmp(cmd, "help") == 0) {
        if (n > 0) {
          usage(chp, "help");
          continue;
        }
        chprintf(chp, "Commands: help exit ");
        list_commands(chp, shell_local_commands);
        if (scp != NULL)
          list_commands(chp, scp);
        chprintf(chp, "\r\n");
      }
      else if (cmdexec(shell_local_commands, chp, cmd, n, args) &&
          ((scp == NULL) || cmdexec(scp, chp, cmd, n, args))) {
        chprintf(chp, "%s", cmd);
        chprintf(chp, " ?\r\n");
      }
    }
  }
  shellExit(MSG_OK);
}

/**
 * @brief   Shell manager initialization.
 *
 * @api
 */
void shellInit(void) {

  chEvtObjectInit(&shell_terminated);
}

/**
 * @brief   Terminates the shell.
 * @note    Must be invoked from the command handlers.
 * @note    Does not return.
 *
 * @param[in] msg       shell exit code
 *
 * @api
 */
void shellExit(msg_t msg) {

  /* Atomically broadcasting the event source and terminating the thread,
     there is not a chSysUnlock() because the thread terminates upon return.*/
  chSysLock();
  chEvtBroadcastI(&shell_terminated);
  chThdExitS(msg);
}

/**
 * @brief   Reads a whole line from the input channel.
 * @note    Input chars are echoed on the same stream object with the
 *          following exceptions:
 *          - DEL and BS are echoed as BS-SPACE-BS.
 *          - CR is echoed as CR-LF.
 *          - 0x4 is echoed as "^D".
 *          - Other values below 0x20 are not echoed.
 *          .
 *
 * @param[in] chp       pointer to a @p BaseSequentialStream object
 * @param[in] line      pointer to the line buffer
 * @param[in] size      buffer maximum length
 * @return              The operation status.
 * @retval true         the channel was reset or CTRL-D pressed.
 * @retval false        operation successful.
 *
 * @api
 */
bool shellGetLine(BaseSequentialStream *chp, char *line, unsigned size) {
  char *p = line;

  while (true) {
    char c;

    if (chSequentialStreamRead(chp, (uint8_t *)&c, 1) == 0)
      return true;
    if (c == 4) {
      chprintf(chp, "^D");
      return true;
    }
    if ((c == 8) || (c == 127)) {
      if (p != line) {
        chSequentialStreamPut(chp, c);
        chSequentialStreamPut(chp, 0x20);
        chSequentialStreamPut(chp, c);
        p--;
      }
      continue;
    }
    if (c == '\r') {
      chprintf(chp, "\r\n");
      *p = 0;
      return false;
    }
    if (c < 0x20)
      continue;
    if (p < line + size - 1) {
      chSequentialStreamPut(chp, c);
      *p++ = (char)c;
    }
  }
}

/** @} */