/*!@file
  \brief   APC Directory Scanner
  \details This hand-written parser/scanner traverses a directory tree and
           tokenizes elements of the structure which correspond to APC grammar.
           The parser is implemented as a 2D stack which populates a list of
           child directories at each depth, handling only the leaf nodes
           (regular files) of the directory open at the current depth to
           conserve memory and speed up traversal.
           The scanner works with the lexer to lexically analyze text, and
           assumes the existence of an external 'lex' function
  \author  Jordan Lavatai
  \date    Aug 2016
  ----------------------------------------------------------------------------*/
/* Standard */
#include <stdio.h>  //print
#include <errno.h>  //errno
/* Posix */
#include <err.h>    //warnx
#include <stdlib.h> //exit
#include <unistd.h> //chdir
#include <dirent.h> //opendir
#include <unistr.h> //unicode strings
#include <string.h> //strlen
/* Internal */
#include "parser.tab.h"
/* Public */
void  scanner_quit(void);
int   scanner_scandir(DIR*);
/* Private */
static
int   scanner_scandir_r(DIR*);
extern //lexer.rl
int   lexer_init(void);
extern //lexer.rl
void  lexer_quit(void);
extern //lexer.rl
int   lexer_lexfile(uint8_t*);
extern //lexer.rl
int   lexer_lexdir(uint8_t*);
extern //lexer.rl
void  lexer_closedir(void);

/* Scan directory stream
   Recursively scans the provided directory, sending CLOPEN and CLCLOSE tokens
   to the parser when entering new directories (classes)
*/
int scanner_scandir
( DIR* dirp )
{ int scandir_status;
  if (lexer_init())
    return -1;
  scandir_status = scanner_scandir_r(dirp);
  lexer_quit();
  return scandir_status;
}

static
int scanner_scandir_r
( DIR* dirp )
{ DIR* cdirp;
  struct dirent* direntp;
 scan_next_dirent:
  errno = 0;
  direntp = readdir(dirp);
  if (errno)
    goto libfail;
  if (direntp != NULL)
    { if (*(direntp->d_name) == '.') //skip hidden or relative files
	goto scan_next_dirent;
      switch (direntp->d_type)
	{ case DT_REG:
	    lexer_lexfile((uint8_t*)direntp->d_name);
	    goto scan_next_dirent;
	  case DT_DIR:
	    lexer_lexdir((uint8_t*)direntp->d_name);  //lex the dirname
	    if (chdir(direntp->d_name))    //change to the specified dir
	      goto libfail;
	    errno = 0;
	    if ((cdirp = opendir(".")) == NULL || errno) //open it
	      goto libfail;
	    if(scanner_scandir_r(cdirp))  //scan the directory
	      goto libfail;
	    if (chdir(".."))              //return to the parent dir
	      goto libfail;
            lexer_closedir();            //push "Close Directory" token
	    goto scan_next_dirent;        //continue scan
          case DT_UNKNOWN:
	    warnx("unknown file %s: ignoring", direntp->d_name);
          default:
	    goto scan_next_dirent;
	}
    }
  return closedir(dirp);
 libfail:
  perror("scanner_scandir");
  return -1;
}