#include <u.h>
#include <libc.h>
#include <thread.h>
#include <bio.h>

#include "apl9.h"

Symtab *globalsymtab;

Symtab *newsymtab(void);
void freesymtab(Symtab *);

Datum *getalpha(void);
Datum *getomega(void);
Datum *getalphao(void);
Datum *getomegao(void);
void setalpha(Datum *);
void setsyntaxerr(Datum *);

Symbol *
getsym(Rune *name, int fresh)
{
	ThreadData *td = getthreaddata();
	DfnFrame *dfn = td->currentdfn;
	Symtab *tab;
	int done = 0;
	do{
		if(dfn != nil)
			tab = dfn->symtab;
		else
			tab = globalsymtab;
		for(int i = 0; i < tab->nsyms; i++){
			if(runestrcmp(tab->syms[i]->name, name) == 0)
				return tab->syms[i];
		}
		if(dfn)
			dfn = dfn->chain;
		else
			done = 1;
	}while(!done && !fresh);

	/* make sure to allocate in the most local scope if the symbol is not found */
	if(td->currentdfn)
		tab = td->currentdfn->symtab;

	tab->nsyms++;
	tab->syms = erealloc(tab->syms, sizeof(Symbol *) * tab->nsyms);
	tab->syms[tab->nsyms-1] = emalloc(sizeof(Symbol));
	tab->syms[tab->nsyms-1]->name = runestrdup(name);
	tab->syms[tab->nsyms-1]->getfn = nil;
	tab->syms[tab->nsyms-1]->setfn = nil;
	tab->syms[tab->nsyms-1]->value = nil;
	return tab->syms[tab->nsyms-1];
}

Symtab *
newsymtab(void)
{
	Symtab *tab = emalloc(sizeof(Symtab));
	tab->nsyms = 0;
	tab->syms = nil;
	tab->io = globalIO();
	tab->div = globalDIV();

	return tab;
}

void
freesymtab(Symtab *tab)
{
	int i;
	for(i = 0; i < tab->nsyms; i++){
		Symbol *s = tab->syms[i];
		freedatum(s->value);
		free(s->name);
	}
	free(tab->syms);
	free(tab);
}

void
initsymtab(void)
{
	globalsymtab = newsymtab();
	Symbol *s;
	s = getsym(L"⍺", 1);
	s->getfn = getalpha;
	s->setfn = setalpha;

	s = getsym(L"⍵", 1);
	s->getfn = getomega;
	s->setfn = setsyntaxerr;

	s = getsym(L"⍶", 1);
	s->getfn = getalphao;
	s->setfn = setsyntaxerr;

	s = getsym(L"⍹", 1);
	s->getfn = getomegao;
	s->setfn = setsyntaxerr;
}

DfnFrame *
getcurrentdfn(void)
{
	ThreadData *td = getthreaddata();
	return td->currentdfn;
}

DfnFrame *
pushdfnframe(Rune *code, DfnFrame *scope, Datum *lefto, Datum *righto, Array *left, Array *right)
{
	ThreadData *td = getthreaddata();
	DfnFrame *new = emalloc(sizeof(DfnFrame));
	new->code = code;
	new->symtab = newsymtab();
	new->lefto = lefto;
	new->righto = righto;
	if(lefto)
		incdatumref(lefto);
	if(righto)
		incdatumref(righto);
	if(left){
		new->left = allocdatum(ArrayTag, 0);
		new->left->array = left;
		incarrayref(left);
	}else
		new->left = nil;
	new->right = right;
	incarrayref(right);
	new->prev = td->currentdfn;
	new->chain = scope;
	td->currentdfn = new;
	return new;
}

void
popdfnframe(void)
{
	ThreadData *td = getthreaddata();
	if(td->currentdfn != nil){
		DfnFrame *prev = td->currentdfn->prev;
		freesymtab(td->currentdfn->symtab);
		freedatum(td->currentdfn->lefto);
		freedatum(td->currentdfn->righto);
		freedatum(td->currentdfn->left);
		freearray(td->currentdfn->right);
		free(td->currentdfn);
		td->currentdfn = prev;
	}
}

vlong
globalIO(void)
{
	ThreadData *td = getthreaddata();
	if(td->currentdfn)
		return td->currentdfn->symtab->io;
	else if(globalsymtab)
		return globalsymtab->io;
	else
		return 1;
}

void
globalIOset(vlong io)
{
	ThreadData *td = getthreaddata();
	if(td->currentdfn)
		td->currentdfn->symtab->io = io;
	else
		globalsymtab->io = io;
}

int
globalDIV(void)
{
	ThreadData *td = getthreaddata();
	if(td->currentdfn)
		return td->currentdfn->symtab->div;
	else if(globalsymtab)
		return globalsymtab->div;
	else
		return 0;
}

void
globalDIVset(int div)
{
	ThreadData *td = getthreaddata();
	if(td->currentdfn)
		td->currentdfn->symtab->div = div;
	else
		globalsymtab->div = div;
}

/* getters and setters for ⍺⍵⍶⍹ */
Datum *
getalpha(void)
{
	DfnFrame *dfn = getcurrentdfn();
	Datum *res = nil;
	if(dfn == nil || dfn->left == nil)
		throwerror(nil, ESyntax);
	else{
		res = dfn->left;
		incdatumref(res);
	}
	return res;
}

Datum *
getomega(void)
{
	DfnFrame *dfn = getcurrentdfn();
	Datum *res = nil;
	if(dfn == nil || dfn->right == nil)
		throwerror(nil, ESyntax);
	else{
		res = allocdatum(ArrayTag, 0);
		res->array = dfn->right;
		incarrayref(res->array);
	}
	return res;
}

Datum *
getalphao(void)
{
	DfnFrame *dfn = getcurrentdfn();
	Datum *res = nil;
	if(dfn == nil || dfn->lefto == nil)
		throwerror(nil, ESyntax);
	else{
		res = dfn->lefto;
		incdatumref(res);
	}
	return res;
}

Datum *
getomegao(void)
{
	DfnFrame *dfn = getcurrentdfn();
	Datum *res = nil;
	if(dfn == nil || dfn->righto == nil)
		throwerror(nil, ESyntax);
	else{
		res = dfn->righto;
		incdatumref(res);
	}
	return res;
}

void
setalpha(Datum *new)
{
	DfnFrame *dfn = getcurrentdfn();
	if(dfn == nil)
		throwerror(nil, ESyntax);
	if(dfn->left == nil){
		dfn->left = new;
		incdatumref(new);
	}
}

void
setsyntaxerr(Datum *)
{
	throwerror(nil, ESyntax);
}