/*----------------------------------------------------------------------*\
 | DBFrename:  Rename fields in a DBF file.								|
 |																		|
 | ArcView is able to read and display a shapefile whose corresponding	|
 | dbf has two fields with the same name.  However ArcExplorer is not,	|
 | and ArcIMS cannot create a map service using a shapefile whose DBF	|
 | field names are not unique.  Consequently a method to change field	|
 | names in a dbf is needed.											|
 |																		|
 | This program reads the dbf named on the command line, and attempts	|
 | to change the field names.  If an old and new name are specified on	|
 | the command line following the DBF file name, it replaces the old	|
 | field name with the new one.  If these names are not specified, it	|
 | prints all of the field names and attributes, and allows the user to	|
 | change the names of any of the fields, within the constraints of the	|
 | DBF format.															|
 |																		|
 | If the old name specified is a number, it will be interpreted as the	|
 | index of the field whose name should be replaced by new_name.		|
 |																		|
 | Peter N. Schweitzer (U.S. Geological Survey, Reston VA 20192)		|
\*----------------------------------------------------------------------*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define version_id		"1.2"
#define version_date	"5-Oct-2005"
#define version_author	"Peter N. Schweitzer"

#ifdef _WIN32
	#define mode "rb+"
#else
	#define mode "r+"
#endif

static int no_space (char *s) {
	while (*s)
		if (isspace(*s)) return (0);
		else s++;
	return (1);
	}

static int no_punct (char *s) {		/* But allow underscore */
	while (*s)
		if (ispunct(*s) && *s != '_') return (0);
		else s++;
	return (1);
	}

int main (int argc, char *argv[]) {
	char *input_file = NULL;
	char *old_name = NULL;
	char *new_name = NULL;
	FILE *fp;
	unsigned char header[32];
	int i,j,n,fc;
	unsigned char *buffer;
	unsigned char name[16], *s;
	char *e;
	unsigned char **field_name;
	unsigned char string[16];
	int which,done,changed;

	if (argc > 1) {
		input_file = argv[1];
		if (fp = fopen (input_file,mode)) {
			fread (header,32,1,fp);
			n = header[8] + 256*header[9];
			fc = (n - 32)/32;
			printf ("DBFrename %s %s %s\n",version_id,version_date,version_author);
			printf ("Number of fields: %d\n",fc);
			if (field_name = (unsigned char **) malloc (fc * sizeof (char *))) {
				if (buffer = (unsigned char *) malloc (n-32)) {
					fread (buffer,n-32,1,fp);
					for (i=0; i < fc; i++) {
						s = buffer + i * 32;
						field_name[i] = s;
						memcpy (name,s,10);
						name[10] = 0;
						printf ("%d: %10s",i,name);
						printf (" %c",s[11]);
						printf (" %4d",s[12] + 256*(s[13] + 256*(s[14] + 256*s[15])));
						printf (" %2d",s[16]);
						printf (" %2d",s[17]);
						printf ("\n");
						}

					/*--------------------------------------------------*\
					 | Non-interactive mode: just try to make the change
					 |   dbfrename input_file old_name new name
					\*--------------------------------------------------*/

					if (argc > 3) {
						old_name = argv[2];
						new_name = argv[3];
						changed = 0;

						if (isdigit (*old_name))
							which = atoi (old_name);
						else
							for (which=0; which < fc; which++)
								if (stricmp (old_name,field_name[which]) == 0) break;

						if (which != fc)						/* Name doesn't exist?        */
							if (strlen (new_name) < 11) 		/* Name too long?             */
								if (no_space (new_name)) 		/* Name contains whitespace?  */
									if (no_punct (new_name)) { 	/* Name contains punctuation? */
										for (j=0; j < fc; j++)
											if (j != which)
												if (stricmp (new_name,field_name[j]) == 0) break;
										if (j == fc) { 		/* Name same as another field? */
											strcpy (field_name[which],new_name);
											printf ("Ok, new name for field %d is %s\n",which,new_name);
											changed = 1;
											}
										else
											printf ("Error: new name matches an existing field %d.\n",j);
										}
									else
										printf ("Error: field names cannot contain punctuation.\n");
								else
									printf ("Error: field names cannot contain whitespace.\n");
							else
								printf ("Error: field names must be 10 characters or less.\n");
						else
							printf ("Error: %s contains no field named %s.\n",input_file,old_name);

						if (changed) {
							fseek (fp,0L,SEEK_SET);
							fwrite (header,1,32,fp);
							fwrite (buffer,1,n-32,fp);
							fflush (fp);
							}
						exit (changed == 0);
						}

					/*--------------------------------------------------*\
					 | Ask user
					\*--------------------------------------------------*/

					changed = 0;
					done = 0;
					while (!done) {
						printf ("Enter a field number, blank when done.\n");
						printf ("Rename which field?: ");
						fgets (string,16,stdin);
						which = (int) strtol (string,&e,0);
						if (e != (char *) string) {
							printf ("Old name is %s; Enter new name: ",field_name[which]);
							fgets (string,16,stdin);

							/* Trim leading and trailing spaces */

							s = string + strlen (string) - 1;
							if (*s == '\n') *s-- = 0;
							if (*s == '\r') *s-- = 0;
							while (s >= string && isspace(*s)) *s-- = 0;
							for (s=string; *s && isspace(*s); s++);
							strcpy (name,s);

							/* Check for problems                                             */
							if (*name) 							/* Name empty?                */
								if (strlen (name) < 11) 		/* Name too long?             */
									if (no_space (name)) 		/* Name contains whitespace?  */
										if (no_punct (name)) { 	/* Name contains punctuation? */
											for (j=0; j < fc; j++)
												if (j != which)
													if (stricmp (name,field_name[j]) == 0) break;
											if (j == fc) { 		/* Name same as another field? */
												strcpy (field_name[which],name);
												printf ("Ok, new name for field %d is %s\n",which,name);
												changed = 1;
												}
											else
												printf ("Sorry, that name matches field %d.  Name not changed.\n",j);
											}
										else
											printf ("Sorry, field names cannot contain punctuation.  Name not changed.\n");
									else
										printf ("Sorry, field name cannot contain whitespace.  Name not changed.\n");
								else
									printf ("Sorry, new name must be 10 characters or less.  Name not changed.\n");
							else
								printf ("Sorry, no new name given.  Name not changed.\n");
							}
						else done = 1;
						}

					/* If changes were made, show user and confirm save. */

					if (changed) {
						printf ("Field names as modified:\n");
						for (i=0; i < fc; i++)
							printf ("%d: %10s\n",i,field_name[i]);
						printf ("Save these in the file? [y/N]: ");
						fgets (string,16,stdin);
						if (toupper(*string) == 'Y') {
							fseek (fp,0L,SEEK_SET);
							fwrite (header,1,32,fp);
							fwrite (buffer,1,n-32,fp);
							fflush (fp);
							}
						}
					free (buffer);
					}
				else {
					fprintf (stderr,"Error: could not allocate space for field header info (%d bytes)\n",n-32);
					fclose (fp);
					exit (1);
					}
				free (field_name);
				}
			else {
				fprintf (stderr,"Error: could not allocate space for field name pointers (%d bytes)\n",fc*sizeof(char *));
				fclose (fp);
				exit (1);
				}
			fclose (fp);
			}
		else {
			printf ("Error: could not open input file %s\n",input_file);
			exit (1);
			}
		}
	else {
		printf ("DBFrename %s %s %s\n",version_id,version_date,version_author);
		printf ("  Rename fields in a DBF file.  Useful for fixing identical field names.\n");
		printf ("Usage: %s input_file.dbf [old_name|index new_name]\n",argv[0]);
		printf ("  If old and new names are not specified, this program carries out a dialog\n");
		printf ("  with the user at the command line.\n");
		}
	exit (0);
	}

/*----------------------------------------------------------------------*\
\*----------------------------------------------------------------------*/