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

#include "memory.h"
#include "parser.h"

char* readfile(const char *fname){
	FILE *f=fopen(fname,"rb");
	if(!f)return NULL;
	if(fseek(f,0,SEEK_END)==-1){fclose(f); return NULL;}
	long flen=ftell(f);
	if(flen==-1){fclose(f); return NULL;}
	rewind(f);

	char *buf=malloc(flen+1);
	if(!buf){fclose(f); return NULL;}
	fread(buf,1,flen,f);
	if(ferror(f)){fclose(f); free(buf); return NULL;}
	if(memchr(buf,'\0',flen)!=NULL){
		fprintf(stderr,"Invalid null char in file '%s'\n",fname);
		exit(1);
	}
	buf[flen]='\0';
	fclose(f);
	return buf;
}

char *readstdin(void){
	int bufsz=1024,cursor=0;
	char *buf=malloc(bufsz);
	if(!buf)return NULL;
	while(true){
		if(cursor==bufsz-1){
			bufsz*=2;
			char *newbuf=realloc(buf,bufsz);
			if(!newbuf){
				free(buf);
				return NULL;
			}
			buf=newbuf;
		}
		int nread=fread(buf,1,bufsz-cursor-1,stdin);
		if(nread>0&&memchr(buf,'\0',nread)!=NULL){
			fprintf(stderr,"Invalid null char on stdin file\n");
			exit(1);
		}
		cursor+=nread;
		if(nread<bufsz-cursor-1){
			if(feof(stdin))break;
			if(ferror(stdin)){
				free(buf);
				return NULL;
			}
		}
	}
	buf[cursor]='\0';
	return buf;
}


void usage(const char *argv0){
	fprintf(stderr,"Usage: %s <source file>\n",argv0);
}

int main(int argc,char **argv){
	if(argc!=2){
		usage(argv[0]);
		return 1;
	}
	char *source;
	if(strcmp(argv[1],"-")==0)source=readstdin();
	else source=readfile(argv[1]);
	if(!source){
		fprintf(stderr,"Error reading %s\n",strcmp(argv[1],"-")==0?"from stdin":argv[1]);
		return 1;
	}

	char *errmsg;
	AST *ast=parse(source,&errmsg);
	if(ast==NULL){
		fprintf(stderr,"%s\n",errmsg);
		free(errmsg);
		return 1;
	}
	ast_debug(stderr,ast);
	ast_free(ast);
}