/*
 * Copyright © 2016 Keith Packard <keithp@keithp.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 */

#include "ao_scheme.h"

static void cons_mark(void *addr)
{
	struct ao_scheme_cons	*cons = addr;

	for (;;) {
		ao_poly cdr = cons->cdr;

		ao_scheme_poly_mark(cons->car, 1);
		if (!cdr)
			break;
		if (!ao_scheme_is_cons(cdr)) {
			ao_scheme_poly_mark(cdr, 0);
			break;
		}
		cons = ao_scheme_poly_cons(cdr);
		if (ao_scheme_mark_memory(&ao_scheme_cons_type, cons))
			break;
	}
}

static int cons_size(void *addr)
{
	(void) addr;
	return sizeof (struct ao_scheme_cons);
}

static void cons_move(void *addr)
{
	struct ao_scheme_cons	*cons = addr;

	if (!cons)
		return;

	for (;;) {
		ao_poly			cdr;
		struct ao_scheme_cons	*c;
		int	ret;

		MDBG_MOVE("cons_move start %d (%d, %d)\n",
			  MDBG_OFFSET(cons), MDBG_OFFSET(ao_scheme_ref(cons->car)), MDBG_OFFSET(ao_scheme_ref(cons->cdr)));
		(void) ao_scheme_poly_move(&cons->car, 1);
		cdr = cons->cdr;
		if (!cdr)
			break;
		if (!ao_scheme_is_cons(cdr)) {
			(void) ao_scheme_poly_move(&cons->cdr, 0);
			break;
		}
		c = ao_scheme_poly_cons(cdr);
		ret = ao_scheme_move_memory(&ao_scheme_cons_type, (void **) &c);
		if (c != ao_scheme_poly_cons(cons->cdr))
			cons->cdr = ao_scheme_cons_poly(c);
		MDBG_MOVE("cons_move end %d (%d, %d)\n",
			  MDBG_OFFSET(cons), MDBG_OFFSET(ao_scheme_ref(cons->car)), MDBG_OFFSET(ao_scheme_ref(cons->cdr)));
		if (ret)
			break;
		cons = c;
	}
}

const struct ao_scheme_type ao_scheme_cons_type = {
	.mark = cons_mark,
	.size = cons_size,
	.move = cons_move,
	.name = "cons",
};

struct ao_scheme_cons *ao_scheme_cons_free_list;

struct ao_scheme_cons *
ao_scheme_cons_cons(ao_poly car, ao_poly cdr)
{
	struct ao_scheme_cons	*cons;

	if (ao_scheme_cons_free_list) {
		cons = ao_scheme_cons_free_list;
		ao_scheme_cons_free_list = ao_scheme_poly_cons(cons->cdr);
	} else {
		ao_scheme_poly_stash(car);
		ao_scheme_poly_stash(cdr);
		cons = ao_scheme_alloc(sizeof (struct ao_scheme_cons));
		cdr = ao_scheme_poly_fetch();
		car = ao_scheme_poly_fetch();
		if (!cons)
			return NULL;
	}
	cons->car = car;
	cons->cdr = cdr;
	return cons;
}

struct ao_scheme_cons *
ao_scheme_cons_cdr(struct ao_scheme_cons *cons)
{
	ao_poly	cdr = cons->cdr;
	if (cdr == AO_SCHEME_NIL)
		return NULL;
	if (!ao_scheme_is_cons(cdr)) {
		(void) ao_scheme_error(AO_SCHEME_INVALID, "improper cdr %v", cdr);
		return NULL;
	}
	return ao_scheme_poly_cons(cdr);
}

ao_poly
ao_scheme_cons(ao_poly car, ao_poly cdr)
{
	return ao_scheme_cons_poly(ao_scheme_cons_cons(car, cdr));
}

static struct ao_scheme_cons *
ao_scheme_cons_copy(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons	*head = NULL;
	struct ao_scheme_cons	*tail = NULL;

	while (cons) {
		struct ao_scheme_cons	*new;
		ao_poly cdr;

		ao_scheme_cons_stash(cons);
		ao_scheme_cons_stash(head);
		ao_scheme_cons_stash(tail);
		new = ao_scheme_alloc(sizeof (struct ao_scheme_cons));
		tail = ao_scheme_cons_fetch();
		head = ao_scheme_cons_fetch();
		cons = ao_scheme_cons_fetch();
		if (!new)
			return AO_SCHEME_NIL;
		new->car = cons->car;
		new->cdr = AO_SCHEME_NIL;
		if (!head)
			head = new;
		else
			tail->cdr = ao_scheme_cons_poly(new);
		tail = new;
		cdr = cons->cdr;
		if (!ao_scheme_is_cons(cdr)) {
			tail->cdr = cdr;
			break;
		}
		cons = ao_scheme_poly_cons(cdr);
	}
	return head;
}

void
ao_scheme_cons_free(struct ao_scheme_cons *cons)
{
#if DBG_FREE_CONS
	ao_scheme_cons_check(cons);
#endif
	while (cons) {
		ao_poly cdr = cons->cdr;
		cons->cdr = ao_scheme_cons_poly(ao_scheme_cons_free_list);
		ao_scheme_cons_free_list = cons;
		cons = ao_scheme_poly_cons(cdr);
	}
}

void
ao_scheme_cons_write(FILE *out, ao_poly c, bool write)
{
	struct ao_scheme_cons	*cons = ao_scheme_poly_cons(c);
	struct ao_scheme_cons	*clear = cons;
	ao_poly			cdr;
	int			written = 0;

	ao_scheme_print_start();
	fprintf(out, "(");
	while (cons) {
		if (written != 0)
			fprintf(out, " ");

		/* Note if there's recursion in printing. Not
		 * as good as actual references, but at least
		 * we don't infinite loop...
		 */
		if (ao_scheme_print_mark_addr(cons)) {
			fprintf(out, "...");
			break;
		}

		ao_scheme_poly_write(out, cons->car, write);

		/* keep track of how many pairs have been printed */
		written++;

		cdr = cons->cdr;
		if (!ao_scheme_is_cons(cdr)) {
			fprintf(out, " . ");
			ao_scheme_poly_write(out, cdr, write);
			break;
		}
		cons = ao_scheme_poly_cons(cdr);
	}
	fprintf(out, ")");

	if (ao_scheme_print_stop()) {

		/* If we're still printing, clear the print marks on
		 * all printed pairs
		 */
		while (written--) {
			ao_scheme_print_clear_addr(clear);
			clear = ao_scheme_poly_cons(clear->cdr);
		}
	}
}

int
ao_scheme_cons_length(struct ao_scheme_cons *cons)
{
	int	len = 0;
	while (cons) {
		len++;
		cons = ao_scheme_cons_cdr(cons);
	}
	return len;
}

ao_poly
ao_scheme_do_car(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons *pair;

	if (!ao_scheme_parse_args(_ao_scheme_atom_car, cons,
				  AO_SCHEME_CONS, &pair,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	return pair->car;
}

ao_poly
ao_scheme_do_cdr(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons *pair;

	if (!ao_scheme_parse_args(_ao_scheme_atom_cdr, cons,
				  AO_SCHEME_CONS, &pair,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	return pair->cdr;
}

ao_poly
ao_scheme_do_cons(struct ao_scheme_cons *cons)
{
	ao_poly	car, cdr;

	if (!ao_scheme_parse_args(_ao_scheme_atom_cons, cons,
				  AO_SCHEME_POLY, &car,
				  AO_SCHEME_POLY, &cdr,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	return ao_scheme_cons(car, cdr);
}

ao_poly
ao_scheme_do_last(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons	*pair;

	if (!ao_scheme_parse_args(_ao_scheme_atom_last, cons,
				  AO_SCHEME_CONS | AO_SCHEME_ARG_NIL_OK, &pair,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	while (pair) {
		if (!pair->cdr)
			return pair->car;
		pair = ao_scheme_cons_cdr(pair);
	}
	return AO_SCHEME_NIL;
}

ao_poly
ao_scheme_do_length(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons	*pair;
	if (!ao_scheme_parse_args(_ao_scheme_atom_length, cons,
				  AO_SCHEME_CONS | AO_SCHEME_ARG_NIL_OK, &pair,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	return ao_scheme_integer_poly(ao_scheme_cons_length(pair));
}

ao_poly
ao_scheme_do_list_copy(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons	*pair;

	if (!ao_scheme_parse_args(_ao_scheme_atom_list2dcopy, cons,
				  AO_SCHEME_CONS | AO_SCHEME_ARG_NIL_OK, &pair,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	return ao_scheme_cons_poly(ao_scheme_cons_copy(pair));
}

ao_poly
ao_scheme_do_list_tail(struct ao_scheme_cons *cons)
{
	ao_poly			list;
	int32_t			v;

	if (!ao_scheme_parse_args(_ao_scheme_atom_list2dtail, cons,
				  AO_SCHEME_CONS | AO_SCHEME_ARG_NIL_OK | AO_SCHEME_ARG_RET_POLY, &list,
				  AO_SCHEME_INT, &v,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;

	while (v > 0) {
		if (!list)
			return ao_scheme_error(AO_SCHEME_INVALID, "%v: ran off end", _ao_scheme_atom_list2dtail);
		if (!ao_scheme_is_cons(list))
			return ao_scheme_error(AO_SCHEME_INVALID, "%v: invalid list", _ao_scheme_atom_list2dtail);
		list = ao_scheme_poly_cons(list)->cdr;
		v--;
	}
	return list;
}

ao_poly
ao_scheme_do_pairp(struct ao_scheme_cons *cons)
{
	ao_poly val;

	if (!ao_scheme_parse_args(_ao_scheme_atom_pair3f, cons,
				  AO_SCHEME_POLY, &val,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	if (ao_scheme_is_pair(val))
		return _ao_scheme_bool_true;
	return _ao_scheme_bool_false;
}

/* This one is special -- a list is either nil or
 * a 'proper' list with only cons cells
 */
ao_poly
ao_scheme_do_listp(struct ao_scheme_cons *cons)
{
	ao_poly val;

	if (!ao_scheme_parse_args(_ao_scheme_atom_pair3f, cons,
				  AO_SCHEME_POLY, &val,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	for (;;) {
		if (val == AO_SCHEME_NIL)
			return _ao_scheme_bool_true;
		if (!ao_scheme_is_cons(val))
			return _ao_scheme_bool_false;
		val = ao_scheme_poly_cons(val)->cdr;
	}
}

ao_poly
ao_scheme_do_set_car(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons	*pair;
	ao_poly			val;

	if (!ao_scheme_parse_args(_ao_scheme_atom_set2dcar21, cons,
				  AO_SCHEME_CONS, &pair,
				  AO_SCHEME_POLY, &val,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	pair->car = val;
	return val;
}

ao_poly
ao_scheme_do_set_cdr(struct ao_scheme_cons *cons)
{
	struct ao_scheme_cons	*pair;
	ao_poly			val;

	if (!ao_scheme_parse_args(_ao_scheme_atom_set2dcar21, cons,
				  AO_SCHEME_CONS, &pair,
				  AO_SCHEME_POLY, &val,
				  AO_SCHEME_ARG_END))
		return AO_SCHEME_NIL;
	pair->cdr = val;
	return val;
}