/*
 *  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 cl_llist_err corelibs_llist_create (void *, void (*) (void *), cl_llist_t **);

static cl_llist_err corelibs_llist_link (uintmax_t, ...);
static cl_llist_err corelibs_llist_rep (cl_llist_t *, cl_llist_t *);

static cl_llist_err corelibs_llist_free_list (cl_llist_t *);
static cl_llist_err corelibs_llist_free_elem (cl_llist_t *);

static cl_llist_err corelibs_llist_set_cont (cl_llist_t *, void *);
static cl_llist_err corelibs_llist_set_free (cl_llist_t *, void (*) (void *));

static cl_llist_err corelibs_llist_get_next (const cl_llist_t *, cl_llist_t **);
static cl_llist_err corelibs_llist_get_prev (const cl_llist_t *, cl_llist_t **);
static cl_llist_err corelibs_llist_get_cont (const cl_llist_t *, void **);

static void corelibs_llist_remove (cl_llist_t *);

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

enum { // Avoid collision in error numbers
	CORELIBS_LLIST_ERR_ARGS_MIS = -4,
	CORELIBS_LLIST_ERR_UNDEF,
	CORELIBS_LLIST_ERR_MEM_NULL,
	CORELIBS_LLIST_ERR_MEM_ALLOC,
	CORELIBS_LLIST_ERR_UNK = 0,
	CORELIBS_LLIST_ERR_OK  = 1,
};

struct corelibs_llist_interface const cl_llist = {
  .create = corelibs_llist_create,
  .link   = corelibs_llist_link,
  .rep    = corelibs_llist_rep,
  .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_MEM_NULL,
      .alloc = CORELIBS_LLIST_ERR_MEM_ALLOC,
    },
    .args = {
      .mis = CORELIBS_LLIST_ERR_ARGS_MIS,
    },
  },
};

static cl_llist_err
corelibs_llist_create (void *c, void (*const f) (void *), cl_llist_t **s) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (s == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (!err) {
		cl_llist_t *cur = malloc (sizeof (*cur));
		if (cur != NULL) {
			cur->prev = NULL;
			cur->next = NULL;
			cur->cont = c;
			cur->free = f;
			*s        = cur;
		} else {
			err = CORELIBS_LLIST_ERR_MEM_ALLOC;
		}
	}
	return err;
}

static cl_llist_err
corelibs_llist_free_list (cl_llist_t *l) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (l == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (!err) {
		// Free previous elements if we have any
		if (l->prev != NULL) {
			for (cl_llist_t *p = l->prev; p != NULL;) {
				cl_llist_t *c = p;
				p             = p->prev;
				corelibs_llist_remove (c);
			}
		}

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

static cl_llist_err
corelibs_llist_free_elem (cl_llist_t *l) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (l == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (!err) {
		corelibs_llist_remove (l);
	}
	return err;
}

static cl_llist_err
corelibs_llist_link (uintmax_t cnt, ...) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (cnt <= 1) err = CORELIBS_LLIST_ERR_ARGS_MIS;
	if (!err) {
		va_list ap;
		va_start (ap, cnt);

		uintmax_t   ccnt = 0;
		cl_llist_t *a = NULL, *b = NULL;
		while (ccnt < cnt) {
			a = b;
			b = va_arg (ap, cl_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);
	}
	return err;
}

static cl_llist_err
corelibs_llist_rep (cl_llist_t *dest, cl_llist_t *src) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (src == NULL || dest == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (!err) {
		if (dest->prev != NULL) dest->prev->next = src;
		if (dest->next != NULL) dest->next->prev = src;
		corelibs_llist_free_elem (dest);
	}
	return err;
}

static cl_llist_err
corelibs_llist_get_next (const cl_llist_t *e, cl_llist_t **save) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (e == NULL || save == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (e->next == NULL) err = CORELIBS_LLIST_ERR_UNDEF;
	if (!err) {
		*save = e->next;
	}
	return err;
}

static cl_llist_err
corelibs_llist_get_prev (const cl_llist_t *e, cl_llist_t **save) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (e == NULL || save == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (e->prev == NULL) err = CORELIBS_LLIST_ERR_UNDEF;
	if (!err) {
		*save = e->prev;
	}
	return err;
}

static cl_llist_err
corelibs_llist_get_cont (const cl_llist_t *e, void **save) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (e == NULL || save == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (!err) {
		*save = e->cont;
	}
	return err;
}

static cl_llist_err
corelibs_llist_set_cont (cl_llist_t *e, void *i) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (e == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (!err) {
		e->cont = i;
	}
	return err;
}

static cl_llist_err
corelibs_llist_set_free (cl_llist_t *e, void (*const f) (void *)) {
	cl_llist_err err = CORELIBS_LLIST_ERR_OK;
	if (e == NULL) err = CORELIBS_LLIST_ERR_MEM_NULL;
	if (!err) {
		e->free = f;
	}
	return err;
}

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