#include <u.h>
#include <libc.h>
#include <bio.h>
#include <ctype.h>
#include "paper.h"
#include "impl.h"

static List **tail;

List*
construct(Node *l)
{
	List *lh, **save;

	save = tail;
	lh = 0;
	tail = &lh;
	build(l);
	tail = save;

	return lh;
}

int
listlen(List *l)
{
	int len;

	len = 0;
	while(l) {
		len++;
		l = l->next;
	}
	return len;
}

void
build(Node *n)
{
	List *l;
	Node res;

	if(n == 0)
		return;

	switch(n->op) {
	case OLIST:
		build(n->left);
		build(n->right);
		return;
	default:
		ppexpr(n, &res);
		l = pplist(res.store.type);
		l->store = res.store;
		*tail = l;
		tail = &l->next;
	}
}

List*
addlist(List *l, List *r)
{
	List *f;

	if(l == 0)
		return r;

	for(f = l; f->next; f = f->next)
		;
	f->next = r;

	return l;
}

void
append(Node *r, Node *list, Node *val)
{
	List *l, *f;

	l = pplist(val->store.type);
	l->store = val->store;
	l->next = 0;

	r->op = OCONST;
	r->store.type = TLIST;

	if(list->store.l == 0) {
		list->store.l = l;
		r->store.l = l;
		return;
	}
	for(f = list->store.l; f->next; f = f->next)
		;
	f->next = l;
	r->store.l = list->store.l;
}

int
listcmp(List *l, List *r)
{
	if(l == r)
		return 1;

	while(l) {
		if(r == 0)
			return 0;
		if(l->store.type != r->store.type)
			return 0;
		switch(l->store.type) {
		case TINT:
			if(l->store.ival != r->store.ival)
				return 0;
			break;
		case TFLOAT:
			if(l->store.fval != r->store.fval)
				return 0;
			break;
		case TSTRING:
			if(scmp(l->store.string, r->store.string) == 0)
				return 0;
			break;
		case TLIST:
			if(listcmp(l->store.l, r->store.l) == 0)
				return 0;
			break;
		}
		l = l->next;
		r = r->next;
	}
	if(l != r)
		return 0;
	return 1;
}

void
nthelem(List *l, int n, Node *res)
{
	if(n < 0)
		pperror("negative index in []");

	while(l && n--)
		l = l->next;

	res->op = OCONST;
	if(l == nil) {
		res->store.type = TLIST;
		res->store.l = nil;
		return;
	}

	res->store = l->store;
}

void
nthlist(List *l, int n, Node *res)
{
	if(n < 0)
		pperror("negative index in []");

	while(l && n--)
		l = l->next;

	res->op = OCONST;
	if(l == nil) {
		res->store.type = TLIST;
		res->store.l = nil;
		return;
	}

	res->store.type = TLIST;
	res->store.l = l;
}

void
delete(List *l, int n, Node *res)
{
	List **tl;

	if(n < 0)
		pperror("negative index in delete");

	res->op = OCONST;
	res->store.type = TLIST;
	res->store.l = l;

	for(tl = &res->store.l; l && n--; l = l->next)
		tl = &l->next;

	if(l == 0)
		pperror("element beyond end of list");
	*tl = l->next;
}

List*
listvar(char *s, vlong v)
{
	List *l, *tl;

	tl = pplist(TLIST);

	l = pplist(TSTRING);
	tl->store.l = l;
	l->store.string = strnode(s);
	l->next = pplist(TINT);
	l = l->next;
	l->store.ival = v;

	return tl;
}