/*
 * queue.c
 * compilation of a list of packages into a world dependency set
 *
 * Copyright (c) 2012 pkgconf authors (see AUTHORS).
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * This software is provided 'as is' and without any warranty, express or
 * implied.  In no event shall the authors be liable for any damages arising
 * from the use of this software.
 */

#include <libpkgconf/libpkgconf.h>

/*
 * !doc
 *
 * libpkgconf `queue` module
 * =========================
 *
 * The `queue` module provides an interface that allows easily building a dependency graph from an
 * arbitrary set of dependencies.  It also provides support for doing "preflight" checks on the entire
 * dependency graph prior to working with it.
 *
 * Using the `queue` module functions is the recommended way of working with dependency graphs.
 */

typedef struct {
	pkgconf_node_t iter;
	char *package;
} pkgconf_queue_t;

/*
 * !doc
 *
 * .. c:function:: void pkgconf_queue_push(pkgconf_list_t *list, const char *package)
 *
 *    Pushes a requested dependency onto the dependency resolver's queue.
 *
 *    :param pkgconf_list_t* list: the dependency resolution queue to add the package request to.
 *    :param char* package: the dependency atom requested
 *    :return: nothing
 */
void
pkgconf_queue_push(pkgconf_list_t *list, const char *package)
{
	pkgconf_queue_t *pkgq = calloc(sizeof(pkgconf_queue_t), 1);

	pkgq->package = strdup(package);
	pkgconf_node_insert_tail(&pkgq->iter, pkgq, list);
}

/*
 * !doc
 *
 * .. c:function:: bool pkgconf_queue_compile(pkgconf_client_t *client, pkgconf_pkg_t *world, pkgconf_list_t *list)
 *
 *    Compile a dependency resolution queue into a dependency resolution problem if possible, otherwise report an error.
 *
 *    :param pkgconf_client_t* client: The pkgconf client object to use for dependency resolution.
 *    :param pkgconf_pkg_t* world: The designated root of the dependency graph.
 *    :param pkgconf_list_t* list: The list of dependency requests to consider.
 *    :return: true if the built dependency resolution problem is consistent, else false
 *    :rtype: bool
 */
bool
pkgconf_queue_compile(pkgconf_client_t *client, pkgconf_pkg_t *world, pkgconf_list_t *list)
{
	pkgconf_node_t *iter;

	PKGCONF_FOREACH_LIST_ENTRY(list->head, iter)
	{
		pkgconf_queue_t *pkgq;

		pkgq = iter->data;
		pkgconf_dependency_parse(client, world, &world->requires, pkgq->package);
	}

	return (world->requires.head != NULL);
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_queue_free(pkgconf_list_t *list)
 *
 *    Release any memory related to a dependency resolution queue.
 *
 *    :param pkgconf_list_t* list: The dependency resolution queue to release.
 *    :return: nothing
 */
void
pkgconf_queue_free(pkgconf_list_t *list)
{
	pkgconf_node_t *node, *tnode;

	PKGCONF_FOREACH_LIST_ENTRY_SAFE(list->head, tnode, node)
	{
		pkgconf_queue_t *pkgq = node->data;

		free(pkgq->package);
		free(pkgq);
	}
}

static inline unsigned int
pkgconf_queue_verify(pkgconf_client_t *client, pkgconf_pkg_t *world, pkgconf_list_t *list, int maxdepth)
{
	if (!pkgconf_queue_compile(client, world, list))
		return PKGCONF_PKG_ERRF_DEPGRAPH_BREAK;

	return pkgconf_pkg_verify_graph(client, world, maxdepth);
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_queue_apply(pkgconf_client_t *client, pkgconf_list_t *list, pkgconf_queue_apply_func_t func, int maxdepth, void *data)
 *
 *    Attempt to compile a dependency resolution queue into a dependency resolution problem, then attempt to solve the problem and
 *    feed the solution to a callback function if a complete dependency graph is found.
 *
 *    :param pkgconf_client_t* client: The pkgconf client object to use for dependency resolution.
 *    :param pkgconf_list_t* list: The list of dependency requests to consider.
 *    :param pkgconf_queue_apply_func_t func: The callback function to call if a solution is found by the dependency resolver.
 *    :param int maxdepth: The maximum allowed depth for the dependency resolver.  A depth of -1 means unlimited.
 *    :param void* data: An opaque pointer which is passed to the callback function.
 *    :returns: true if the dependency resolver found a solution, otherwise false.
 *    :rtype: bool
 */
bool
pkgconf_queue_apply(pkgconf_client_t *client, pkgconf_list_t *list, pkgconf_queue_apply_func_t func, int maxdepth, void *data)
{
	pkgconf_pkg_t world = {
		.id = "virtual:world",
		.realname = "virtual world package",
		.flags = PKGCONF_PKG_PROPF_STATIC | PKGCONF_PKG_PROPF_VIRTUAL,
	};

	/* if maxdepth is one, then we will not traverse deeper than our virtual package. */
	if (!maxdepth)
		maxdepth = -1;

	if (pkgconf_queue_verify(client, &world, list, maxdepth) != PKGCONF_PKG_ERRF_OK)
		return false;

	if (!func(client, &world, data, maxdepth))
	{
		pkgconf_pkg_free(client, &world);
		return false;
	}

	pkgconf_pkg_free(client, &world);

	return true;
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_queue_validate(pkgconf_client_t *client, pkgconf_list_t *list, pkgconf_queue_apply_func_t func, int maxdepth, void *data)
 *
 *    Attempt to compile a dependency resolution queue into a dependency resolution problem, then attempt to solve the problem.
 *
 *    :param pkgconf_client_t* client: The pkgconf client object to use for dependency resolution.
 *    :param pkgconf_list_t* list: The list of dependency requests to consider.
 *    :param int maxdepth: The maximum allowed depth for the dependency resolver.  A depth of -1 means unlimited.
 *    :returns: true if the dependency resolver found a solution, otherwise false.
 *    :rtype: bool
 */
bool
pkgconf_queue_validate(pkgconf_client_t *client, pkgconf_list_t *list, int maxdepth)
{
	bool retval = true;
	pkgconf_pkg_t world = {
		.id = "virtual:world",
		.realname = "virtual world package",
		.flags = PKGCONF_PKG_PROPF_STATIC | PKGCONF_PKG_PROPF_VIRTUAL,
	};

	/* if maxdepth is one, then we will not traverse deeper than our virtual package. */
	if (!maxdepth)
		maxdepth = -1;

	if (pkgconf_queue_verify(client, &world, list, maxdepth) != PKGCONF_PKG_ERRF_OK)
		retval = false;

	pkgconf_pkg_free(client, &world);

	return retval;
}