/* printf, scanf, stdin, stderr */
#include <stdio.h>
/* malloc, free */
#include <stdlib.h>
/* size_t */
#include <sys/types.h>
/* strdup, strtok_r, strcmp, strncmp */
#include <string.h>
/* basename */
#include <libgen.h>
/* sqlite3_* */
#include <sqlite3.h>

/* ABI version required by the code */
#ifndef REQD_SQLITE_VERSION_NUMBER
#define REQD_SQLITE_VERSION_NUMBER 3007015
#endif
/* ABI version available on target platform */
#ifndef TGT_SQLITE_VERSION_NUMBER
#define TGT_SQLITE_VERSION_NUMBER SQLITE_VERSION_NUMBER
#endif

static const char *zVersionNo = "0.3 (" __DATE__ " " __TIME__ ")";
static int fDbg = 0;
static int fCols = 0;
static char *zColSep = "|";

#if 0
/* readlink */
#include <unistd.h>
/* PAtH_MAX */
#include <limits.h>

static int get_pathname(FILE *f, char *buf, size_t bufsiz)
{
    char fnmbuf[sizeof "/proc/self/fd/0123456789"];
    size_t nr;
    if (sizeof "/proc/self/fd/0" - 1 > snprintf(fnmbuf, sizeof fnmbuf, "/proc/self/fd/%d", fileno(f)) ||
    	0 > (nr = readlink(fnmbuf, buf, bufsiz)) || nr >= bufsiz) {
		return -1;
		}
    buf[nr]='\0';
    return nr;
}

static int line_callback(void *parm, int argc, char **argv, char **azColName) {
	int i;
	(void *) parm;
	
	for (i=0; i<argc; i++) {
	    printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
		}
	printf("\n");
	return 0;
}
#endif

/* provide missing functions from newer ABI if needed */
#if (TGT_SQLITE_VERSION_NUMBER < REQD_SQLITE_VERSION_NUMBER)
#ifndef ArraySize
#define ArraySize(a) ((int)(sizeof(a) / sizeof(*(a))))
#endif
#ifndef ALWAYS
#define ALWAYS(a) (a)
#endif

/*
** Return a static string that describes the kind of error specified in the
** argument.
*/
static const char *sqlite3ErrStr(int rc){
  static const char* const aMsg[] = {
    /* SQLITE_OK          */ "not an error",
    /* SQLITE_ERROR       */ "SQL logic error",
    /* SQLITE_INTERNAL    */ 0,
    /* SQLITE_PERM        */ "access permission denied",
    /* SQLITE_ABORT       */ "query aborted",
    /* SQLITE_BUSY        */ "database is locked",
    /* SQLITE_LOCKED      */ "database table is locked",
    /* SQLITE_NOMEM       */ "out of memory",
    /* SQLITE_READONLY    */ "attempt to write a readonly database",
    /* SQLITE_INTERRUPT   */ "interrupted",
    /* SQLITE_IOERR       */ "disk I/O error",
    /* SQLITE_CORRUPT     */ "database disk image is malformed",
    /* SQLITE_NOTFOUND    */ "unknown operation",
    /* SQLITE_FULL        */ "database or disk is full",
    /* SQLITE_CANTOPEN    */ "unable to open database file",
    /* SQLITE_PROTOCOL    */ "locking protocol",
    /* SQLITE_EMPTY       */ 0,
    /* SQLITE_SCHEMA      */ "database schema has changed",
    /* SQLITE_TOOBIG      */ "string or blob too big",
    /* SQLITE_CONSTRAINT  */ "constraint failed",
    /* SQLITE_MISMATCH    */ "datatype mismatch",
    /* SQLITE_MISUSE      */ "bad parameter or other API misuse",
#ifdef SQLITE_DISABLE_LFS
    /* SQLITE_NOLFS       */ "large file support is disabled",
#else
    /* SQLITE_NOLFS       */ 0,
#endif
    /* SQLITE_AUTH        */ "authorization denied",
    /* SQLITE_FORMAT      */ 0,
    /* SQLITE_RANGE       */ "column index out of range",
    /* SQLITE_NOTADB      */ "file is not a database",
    /* SQLITE_NOTICE      */ "notification message",
    /* SQLITE_WARNING     */ "warning message",
  };
  const char *zErr = "unknown error";
  switch( rc ){
    case SQLITE_ABORT_ROLLBACK: {
      zErr = "abort due to ROLLBACK";
      break;
    }
    case SQLITE_ROW: {
      zErr = "another row available";
      break;
    }
    case SQLITE_DONE: {
      zErr = "no more rows available";
      break;
    }
    default: {
      rc &= 0xff;
      if( ALWAYS(rc>=0) && rc<ArraySize(aMsg) && aMsg[rc]!=0 ){
        zErr = aMsg[rc];
      }
      break;
    }
  }
  return zErr;
}
#define sqlite3_errstr(a) sqlite3ErrStr(a)
#endif

static void ok(void) {
    fprintf( stderr, "OK\n");
}

static void eof(void) {
    fprintf( stderr, "EOF on input\n");
}
	
static int col_callback(void *parm, int argc, char **argv, char **azColName) {
	
	if (parm && *(int*)parm) {
		char ** azHeader = (char **) malloc(argc*sizeof(char *));
		for (int i=0; i<argc; i++) {
			printf("%s%s", (i > 0? zColSep:""), azColName[i]);
			azHeader[i] = strdup(azColName[i]);
			memset(azHeader[i],'=',strlen(azHeader[i]));
			}
		printf("\n");
		for (int i=0; i<argc; i++) {
			printf("%s%s", (i > 0? " ":""), azHeader[i]);
			free(azHeader[i]);
			}
		free(azHeader);
		printf("\n");
		*(int*)parm = 0;
		}
		
	for (int i=0; i<argc; i++) {
		printf("%s%s", (i > 0? zColSep:""), argv[i]);
		}
	printf("\n");
	return 0;
}

static int sql_exec( sqlite3 * db, const char *sql ) {
    char *zErrMsg = 0;
    int cb = /*fDbg ||*/ fCols;
    
	if (fDbg) fprintf( stderr, "About to run SQL ---\n%s\n---\n", sql);
	int rc = sqlite3_exec(db, sql, col_callback, &cb, &zErrMsg);
    if ( rc != SQLITE_OK ) {
    	fprintf(stderr, "SQL error: %s\n", zErrMsg);
    	sqlite3_free(zErrMsg);
    	return 1;
        }
      else if (fDbg) ok();  
    return 0;
}

static int cmdline_exec( sqlite3 *db, int argc, char *argv[]) {
    int rc = 0;
	
	for (int ii=1; ii < argc; ++ii) {
		rc = sql_exec(db, argv[ii]);
	    if ( rc != 0 ) {
	    	return 1;
	    }
	}
	return rc;
}

static int stream_exec( FILE * ff, sqlite3 *db) {
	size_t bsiz = 4096;
	char * zStmt = (char *)malloc(bsiz);
	size_t nStmt;
	size_t nStmtEnd = 0;
	int rc = 0;
	/*
	 * escaping " %n%<size>[^;]%n%c%n":
	 * maybe trim whitespace, non-; string; possible ;
	 */
	const char fmt[] = "%s%%n%%%u[^;]%%n%%c%%n";
	char sfmt[32];
	
	/* alloc failed? */
	if (!zStmt) return 1;
	/* empty text */
	*zStmt = '\0';
	for (char *pStmt = zStmt; rc == 0; pStmt += (nStmtEnd > 0? nStmtEnd: nStmt)) {
		/* if the allocation is full (include final \0), increase */
		if (pStmt+1 >= zStmt+bsiz) {
			char *zz = (char *)sqlite3_realloc(zStmt,bsiz+=4096);
			if (!zz) {
				rc = 1; break;
				}
			pStmt = zz + (pStmt - zStmt);
			zStmt = zz;
			}
		/* set the text field width, allowing for extra \0 */	
		rc = snprintf( sfmt, sizeof sfmt, fmt, (pStmt==zStmt? " ":""), bsiz-(pStmt-zStmt)-1 );
		if (rc < 0 || rc > (int)(sizeof sfmt)) {
	        if (fDbg) fprintf( stderr, "Can't set format to read SQL: rc=%d\n", rc);
			rc = 1; break;
			}	
		nStmt = nStmtEnd = 0;
		/* reading possible non-; text followed by possible ; */
		char scln;
		rc = fscanf( ff, ";%n", (int *) &nStmtEnd );
		if (rc >= 0) {
			if (nStmtEnd == 0) { /* not an empty statement */
				int nStart = 0;
				rc = fscanf( ff, sfmt, &nStart, pStmt, &nStmt, &scln, &nStmtEnd );
				if (rc > 0) {
					/* nStmt may randomly be set to 1024 - why?? */
					if (zStmt[0]) {
						if (fDbg) fprintf(stderr, "Adjusting nStmt = %u", nStmt);
						nStmt = strlen(pStmt);
						if (fDbg) fprintf(stderr, " to %u\n", nStmt);
						}
					else if (nStmtEnd > nStmt) {
						nStmt -= nStart;
						}
					nStmtEnd -= nStart;
					}
				}
			else
				scln = ';';
		}
		/* err, EOF or read nothing: fail on error */
		if (rc <= 0 && ferror(ff)) {
	        if (fDbg) {
	            if (EOF == rc) 
	                eof();
	              else
	                fprintf( stderr, "SQL read error: rc=%d\n", rc);
	            }
			rc = 1;
			break;
			}
		if (rc == EOF) {
		    if (zStmt[0]) {
			    /* read some stuff but no ; ? */
			    scln = ';';
			    nStmtEnd = nStmt+1;
	            if (fDbg) fprintf( stderr, "Faking final ; for unterminated input\n");
			    }
			  else {
	            if (fDbg) eof();
	            break;
	            }
	        }
	        
	    if (fDbg) fprintf( stderr, "Read %u characters of SQL (rc=%d)\n", nStmt, rc);
			    
		/* read or faked a possible ; - add it */
		if (nStmtEnd > nStmt) {
	        if (fDbg) fprintf( stderr, "Adding final ;\n");
			pStmt[nStmt] = scln;
			pStmt[nStmtEnd] = '\0';
		}
		/* no final ;, try again */
		if (nStmtEnd == 0 || pStmt[nStmt] != ';') {
	        if (fDbg) fprintf( stderr, "No final ;: reading more\n");
			if (rc > 0) rc = 0; continue;
			}
		/* potential command: what does sqlite say? -> 1, 0, SQLITE_NOMEM */
	    if (fDbg) fprintf( stderr, "About to check SQL ---\n%s\n---\n", zStmt);
		int src = sqlite3_complete(zStmt);
		switch (src) {
			case 1: { /* complete-ish - try it */
	            if (fDbg) ok();
				src = sql_exec(db, zStmt);
				if (rc >= 0) rc = src;
				if (src != 0) break;
					
				/* now ready for the next one */
				pStmt = zStmt;
				nStmt = nStmtEnd = 0;
				zStmt[0] = '\0';
				break;
				}
					
			case 0: { /* incomplete - get more */
				int nn = 0;
				sscanf( zStmt, " ;%n", &nn);
				if (nn == 0) {
					/* non-empty statement */
					if (fDbg) fprintf( stderr, "Incomplete, reading more\n");
					rc = src;
					}
				break;
				}
			default: {
			    if (fDbg) fprintf( stderr, "Error: %s\n", sqlite3_errstr(src));
				rc = 1;
				}
			}
		}

	free(zStmt);

	return rc == EOF? 0: rc;
}

#if 0
static int strcmpany( const char* str, const char* strtest[] ) {
    for (size_t i = 0; strtest[i]; ++i) {
        if (0 == strcmp(str, strtest[i])) return 0;
        }
    return 1;
}
#endif

static int optcmp( const char* str, const char* strtest[], char** val ) {
	
    for (size_t i = 0; strtest[i]; ++i) {
        if (strtest[i][1] == '-') { /* --opt */
            if (val && str[1] == '-') { /* expecting --opt= */
		        char *save = NULL;
		        char *tmpStr = strdup(str);
		        if (tmpStr && (0 == strcmp(strtok_r(tmpStr, "=", &save), strtest[i]))) {
		            *val = strtok_r( NULL, "=", &save);
		            return 0;
		            }
		        free(tmpStr);
		        }
              else if (0 == strcmp(str, strtest[i])) {
                return 0;
		        }
		    }
          else { /* -o */
            if (0 == strncmp(str, strtest[i], 2)) {
                if (val) *val = strdup(str+2);
                return 0;
                }
            }
        }
        
    return 1;
}                

static void usage(const char* progname) {
    fprintf( stderr, "Usage: %s [OPTIONS] [\"SQL command;\" ...] [< SQL_script]\n", progname);
}

static void help(const char* progname) {
    usage(progname);
    fprintf( stderr, "\nExecute SQL commands on SQLite databases\n\n"
"Options:\n"
"  -C, --show-columns        Show column names (if any) as headers of \n"
"                            query results\n"
"  -S,                       String to separate columns in query \n"
"  --column-separator=SEP    results (default \"|\")\n"
"  -v, --verbose             Log details to stderr\n"
"  -V, --version,            Print program version details to stderr\n"
"  --                        Subsequent parameters are not options\n"
"  -h, --help, -?            Print this help to stderr and exit\n"
"\nTo cancel reading from stdin in a POSIX shell, use the input \nredirection \"<&-\".\n" );
}

int main(int argc, char *argv[]) {
    const char zDummyDB[] = ":memory:";
    const char *zHelp[] = { "--help", "-h", "-?", 0 };
    const char *zVersion[] = { "--version", "-V", 0 };
    const char *zVerbose[] = { "--verbose", "-v", 0 };
    const char *zCols[] = { "--show-columns", "-C", 0 };
    const char *zColSepOpt[] = { "--column-separator", "-S", 0 };
    const char *zCont[] = { "--", 0 };
    const char *zProgName = argv[0];
	
    /* process options */
    while (argc >= 2 && (*(argv[1]) == '-')) {
	    char * tmpVal = NULL;
    	if (0 == optcmp(argv[1], zHelp, NULL)) {
    	    help(zProgName);
    	    return 0;
    	    }
    	  else if (0 == optcmp(argv[1], zCols, NULL)) {
            fCols = 1;
            }
    	  else if (0 == optcmp(argv[1], zColSepOpt, &tmpVal)) {
    	    if (tmpVal && *tmpVal) {
                zColSep = tmpVal;
                }
              else if ((argv[1][1] != '-') && (argc > 2)) {
                tmpVal = zColSep = argv[2];
                --argc; ++argv;
                }
            if (!(tmpVal && *tmpVal)) {
    	        fprintf( stderr, "Bad or empty separator option value: %s\n", argv[1]);
                }
            }
    	  else if (0 == optcmp(argv[1], zVersion, NULL)) {
            /* basename() may modify its argument */
            fprintf( stderr, "%s SQLite exec wrapper version %s\n", 
                basename(strdup(zProgName)), zVersionNo);
            }
          else if (0 == optcmp(argv[1], zVerbose, NULL)) {
            fDbg = 1;
		    }
          else if (0 == optcmp(argv[1], zCont, NULL)) {
            --argc; ++argv;
            break;
		    }
          else {
            fprintf( stderr, "Unknown option: %s\n", argv[1]);
		    }
		/* single-char option with no value: next char may be an option */
        if ((argv[1][1] != '-') && !(tmpVal && *tmpVal) && argv[1][2]) {
            (argv[1])++; 
            argv[1][0] = '-';
            }
          else {
            --argc; ++argv;
            }
        }

    if (fDbg) {
        fprintf( stderr, "Options: %s", zVerbose[0]);
        if (fCols) fprintf( stderr, " %s", zCols[0]);
        fprintf( stderr, " separator = '%s'\n", zColSep);
        }
    
	if (fDbg) fprintf( stderr, "About to configure SQLITE_CONFIG_SINGLETHREAD\n");
    int rc = sqlite3_config(SQLITE_CONFIG_SINGLETHREAD);
    if (SQLITE_OK != rc) {
    	fprintf( stderr, "Can't set single-thread: %s\n", sqlite3_errstr(rc));
        return 1;
	    }
	  else if (fDbg) ok();


    sqlite3 *db;
	if (fDbg) fprintf( stderr, "About to open dummy database %s\n", zDummyDB);
    rc = sqlite3_open(zDummyDB, &db);
    if (SQLITE_OK != rc) {
        fprintf(stderr, "Can't open database: %s\n", sqlite3_errstr(rc));
	    }
	  else {
	    if (fDbg) ok();
	
        rc = cmdline_exec( db, argc, argv);

        if (rc == 0) 
            rc = stream_exec( stdin, db);
        }
        
    sqlite3_close(db);
    return rc;
}