#include <err.h>
	#include <stdarg.h>

	#define MAX 255

	#define AND "och"
	#define AVAIL "Tillgänglig: "
	#define ED "red."
	#define PP "ss."
	#define TR "Övers."
	#define VOL "vol."

	void field(char *);
	void entry(void);
	int pf(char *, ...);

	char *name;

	struct entry {
		int a; /* Number of authors. */
		char au[MAX][MAX];	/* author */
		char ad[MAX];		/* internet address */
		char bo[MAX];		/* book */
		char ci[MAX];		/* city */
		char da[MAX];		/* date (year) */
		char ed[MAX];		/* editor */
		char jo[MAX];		/* journal */
		char la[MAX];		/* label */
		char no[MAX];		/* TODO: issue number */
		char pp[MAX];		/* pages */
		char pu[MAX];		/* publisher */
		char se[MAX];		/* TODO: series */
		char ti[MAX];		/* title */
		char tr[MAX];		/* translator */
		char vo[MAX];		/* volume */
		char xx[MAX];		/* extra information */
	} e;

%s ENTRY
%%
^%.*\n		field(yytext); BEGIN(ENTRY);
<ENTRY>^[^%]	entry(); ECHO; BEGIN(0);
<ENTRY><<EOF>>	entry(); yyterminate();
%%

void
main(int argc, char *argv[0])
{
	name = argv[0];
	e.a = 0;
	yylex();
}

/* Save entry field. */
void
field(char *t)
{

#define AS(a,b) if(strncmp(t, a, 2) == 0 && (t += 3)){ strcpy(b, t); return; }

	t++;
	t[strcspn(t, "\n")] = 0;

	AS("au",e.au[e.a++]);
	AS("ad",e.ad);
	AS("bo",e.bo);
	AS("ci",e.ci);
	AS("da",e.da);
	AS("ed",e.ed);
	AS("jo",e.jo);
	AS("la",e.la);
	AS("no",e.no);
	AS("pp",e.pp);
	AS("pu",e.pu);
	AS("se",e.se);
	AS("ti",e.ti);
	AS("tr",e.tr);
	AS("vo",e.vo);
	AS("xx",e.xx);

	fprintf(stderr, "%s: unrecognized field %%%.2s\n", name, t);
	exit(1);
}

/* Print formatted entry. */
void
entry()
{
	int i;

#define EI(a, b) a ? a : b

	/* Print label. */
	pf("% = ", e.la);

	/* Print authors. */
	for(i = 0; i < e.a-2; i++)
		printf("%s, ", e.au[i]);
	if(i == e.a-2)
		printf("%s "AND" ", e.au[i++]);
	if(i == e.a-1)
		printf("%s", e.au[i]);

	/* Print date. */
	(pf(" (%).\n", e.da) || (e.a ? pf(".\n") : 0));

	/* Print title, book/journal. */
	if(*e.bo || *e.jo){
		pf("%.\n", e.ti);
		pf("\\fI%\\fP", EI(e.bo, e.jo));
		pf(" ("ED" %)", e.ed);
	}else
		pf("\\fI%\\fP", e.ti);

	/* Print volume, pages. */
	pf(", "VOL" %", e.vo);
	pf(", "PP" %", e.pp);
	pf(".\n");

	/* Print translator. */
	pf(TR" %.\n", e.tr);

	/* Print city, publisher. */
	(pf("%: %.\n", e.ci, e.pu) || pf("%.\n", e.pu));

	/* Print other information. */
	pf("%.\n", e.xx);

	/* Print internet address. */
	pf(AVAIL"%\n", e.ad);

#define CL(a) *a = 0

	e.a = 0;
	CL(e.ad);
	CL(e.bo);
	CL(e.ci);
	CL(e.da);
	CL(e.ed);
	CL(e.jo);
	CL(e.la);
	CL(e.no);
	CL(e.pp);
	CL(e.pu);
	CL(e.se);
	CL(e.ti);
	CL(e.tr);
	CL(e.vo);
	CL(e.xx);
}

/* Print formatted text if given strings are non-empty. */
int
pf(char *fmt, ...)
{
	char *buf, *p;
	int n;
	va_list ap;

	n = 0;
	for(p = fmt; *p; p++)
		if(*p == '%')
			n++;

	if(!(buf = malloc(strlen(fmt)+n*MAX+1)))
		err(1, "malloc");

	va_start(ap, fmt);
	for(; *fmt; fmt++)
		switch(*fmt){
		case '%':
			p = va_arg(ap, char *);
			if(!p || !*p)
				return 0;
			strcat(buf, p);
			break;
		default:
			strncat(buf, fmt, 1);
		}
	printf("%s", buf);
	va_end(ap);
	return 1;
}