/*
 *  This file is part of corelibs. (https://git.redxen.eu/corelibs)
 *  Copyright (c) 2021 Alex-David Denes
 *
 *  corelibs 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 3 of the License, or
 *  any later version.
 *
 *  corelibs 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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with corelibs.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "llist.h"

#include <stdarg.h> // va_args
#include <stdint.h> // uintmax_t
#include <stdlib.h> // malloc() free()

static llist_err corelibs_llist_create(void*, void (*)(void*), llist_t**);

static llist_err corelibs_llist_link(uintmax_t cnt, ...);

static llist_err corelibs_llist_free_list(llist_t*);
static llist_err corelibs_llist_free_elem(llist_t*);

static llist_err corelibs_llist_set_cont(llist_t*, void*);
static llist_err corelibs_llist_set_free(llist_t*, void (*)(void*));

static llist_err corelibs_llist_get_next(const llist_t*, llist_t**);
static llist_err corelibs_llist_get_prev(const llist_t*, llist_t**);
static llist_err corelibs_llist_get_cont(const llist_t*, void**);

static void corelibs_llist_remove(llist_t*);

struct llist_t {
	struct llist_t *next, *prev;
	void*           cont;
	void (*free)(void*);
};

enum { // Avoid collision in error numbers
	CORELIBS_LLIST_ERR_MARGS = -4,
	CORELIBS_LLIST_ERR_UNDEF,
	CORELIBS_LLIST_ERR_NULL,
	CORELIBS_LLIST_ERR_ALLOC,
	CORELIBS_LLIST_ERR_UNK = 0,
	CORELIBS_LLIST_ERR_OK  = 1,
};

struct corelibs_llist_interface const llist = {
	.create = corelibs_llist_create,
	.link = corelibs_llist_link,
	.free = {
		.list = corelibs_llist_free_list,
		.elem = corelibs_llist_free_elem,
	},
	.set = {
		.cont = corelibs_llist_set_cont,
		.free = corelibs_llist_set_free,
	},
	.get = {
		.prev = corelibs_llist_get_prev,
		.cont = corelibs_llist_get_cont,
		.next = corelibs_llist_get_next,
	},
	.err = {
		.ok = CORELIBS_LLIST_ERR_OK,
		.unknown = CORELIBS_LLIST_ERR_UNK,
		.undef = CORELIBS_LLIST_ERR_UNDEF,
		.mem = {
			.null = CORELIBS_LLIST_ERR_NULL,
			.alloc = CORELIBS_LLIST_ERR_ALLOC,
		},
		.args = {
			.mis = CORELIBS_LLIST_ERR_MARGS,
		},
	},
};

static llist_err
corelibs_llist_create(void* c, void (*const f)(void*), llist_t** s)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	llist_t* cur = malloc(sizeof(*cur));
	if (cur == NULL) {
		err = CORELIBS_LLIST_ERR_ALLOC;
		goto ret;
	}

	cur->prev = NULL;
	cur->next = NULL;
	cur->cont = c;
	cur->free = f;

	*s = cur;
ret:
	return err;
}

static llist_err
corelibs_llist_free_list(llist_t* l)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (l == NULL) {
		err = CORELIBS_LLIST_ERR_NULL;
		goto ret;
	}

	// Free previous elements if we have any
	if (l->prev != NULL) {
		for (llist_t* p = l->prev; p != NULL;) {
			llist_t* c = p;
			p          = p->prev;
			corelibs_llist_remove(c);
		}
	}

	// Free current and next elements
	for (llist_t* p = l; p != NULL;) {
		llist_t* c = p;
		p          = p->next;
		corelibs_llist_remove(c);
	}
ret:
	return err;
}

static llist_err
corelibs_llist_free_elem(llist_t* l)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (l == NULL) {
		err = CORELIBS_LLIST_ERR_NULL;
		goto ret;
	}
	corelibs_llist_remove(l);

ret:
	return err;
}

static llist_err
corelibs_llist_link(uintmax_t cnt, ...)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (cnt <= 1) {
		err = CORELIBS_LLIST_ERR_MARGS;
		goto ret;
	}

	va_list ap;
	va_start(ap, cnt);

	uintmax_t ccnt = 0;
	llist_t * a = NULL, *b = NULL;
	while (ccnt < cnt) {
		a = b;
		b = va_arg(ap, llist_t*);
		if (ccnt < 1) continue; // Fill at least first 2 slots

		if (a != NULL) a->next = b;
		if (b != NULL) b->prev = a;

		ccnt++;
	}

	va_end(ap);
ret:
	return err;
}

static llist_err
corelibs_llist_get_next(const llist_t* e, llist_t** save)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (e == NULL || save == NULL) {
		err = CORELIBS_LLIST_ERR_NULL;
		goto ret;
	}

	if (e->next == NULL) {
		err = CORELIBS_LLIST_ERR_UNDEF;
		goto ret;
	}
	*save = e->next;
ret:
	return err;
}

static llist_err
corelibs_llist_get_prev(const llist_t* e, llist_t** save)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (e == NULL || save == NULL) {
		err = CORELIBS_LLIST_ERR_NULL;
		goto ret;
	}

	if (e->prev == NULL) {
		err = CORELIBS_LLIST_ERR_UNDEF;
		goto ret;
	}
	*save = e->prev;
ret:
	return err;
}

static llist_err
corelibs_llist_get_cont(const llist_t* e, void** save)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (e == NULL || save == NULL) {
		err = CORELIBS_LLIST_ERR_NULL;
		goto ret;
	}

	*save = e->cont;
ret:
	return err;
}

static llist_err
corelibs_llist_set_cont(llist_t* e, void* i)
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (e == NULL) {
		err = CORELIBS_LLIST_ERR_NULL;
		goto ret;
	}

	e->cont = i;
ret:
	return err;
}

static llist_err
corelibs_llist_set_free(llist_t* e, void (*const f)(void*))
{
	llist_err err = CORELIBS_LLIST_ERR_OK;

	if (e == NULL) {
		err = CORELIBS_LLIST_ERR_NULL;
		goto ret;
	}

	e->free = f;
ret:
	return err;
}

// Private function
static void
corelibs_llist_remove(llist_t* e)
{
	corelibs_llist_link(2, e->prev, e->next);
	if (e->free != NULL) e->free(e->cont);
	free(e);
}