/*
 * dependency.c
 * dependency parsing and management
 *
 * Copyright (c) 2011, 2012, 2013 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/stdinc.h>
#include <libpkgconf/libpkgconf.h>

/*
 * !doc
 *
 * libpkgconf `dependency` module
 * ==============================
 *
 * The `dependency` module provides support for building `dependency lists` (the basic component of the overall `dependency graph`) and
 * `dependency nodes` which store dependency information.
 */

typedef enum {
        OUTSIDE_MODULE = 0,
        INSIDE_MODULE_NAME = 1,
        BEFORE_OPERATOR = 2,
        INSIDE_OPERATOR = 3,
        AFTER_OPERATOR = 4,
        INSIDE_VERSION = 5
} parse_state_t;

#define DEBUG_PARSE 0

static const char *
dependency_to_str(const pkgconf_dependency_t *dep, char *buf, size_t buflen)
{
        pkgconf_strlcpy(buf, dep->package, buflen);
        if (dep->version != NULL)
        {
                pkgconf_strlcat(buf, " ", buflen);
                pkgconf_strlcat(buf, pkgconf_pkg_get_comparator(dep), buflen);
                pkgconf_strlcat(buf, " ", buflen);
                pkgconf_strlcat(buf, dep->version, buflen);
        }

        return buf;
}

/* find a colliding dependency that is coloured differently */
static inline pkgconf_dependency_t *
find_colliding_dependency(const pkgconf_dependency_t *dep, const pkgconf_list_t *list)
{
        const pkgconf_node_t *n;

        PKGCONF_FOREACH_LIST_ENTRY(list->head, n)
        {
                pkgconf_dependency_t *dep2 = n->data;

                if (strcmp(dep->package, dep2->package))
                        continue;

                if (dep->flags != dep2->flags)
                        return dep2;
        }

        return NULL;
}

static inline pkgconf_dependency_t *
add_or_replace_dependency_node(pkgconf_client_t *client, pkgconf_dependency_t *dep, pkgconf_list_t *list)
{
        char depbuf[PKGCONF_ITEM_SIZE];
        pkgconf_dependency_t *dep2 = find_colliding_dependency(dep, list);

        /* there is already a node in the graph which describes this dependency */
        if (dep2 != NULL)
        {
                char depbuf2[PKGCONF_ITEM_SIZE];

                PKGCONF_TRACE(client, "dependency collision: [%s/%x] -- [%s/%x]",
                              dependency_to_str(dep, depbuf, sizeof depbuf), dep->flags,
                              dependency_to_str(dep2, depbuf2, sizeof depbuf2), dep2->flags);

                /* prefer the uncoloured node, either dep or dep2 */
                if (dep->flags && dep2->flags == 0)
                {
                        PKGCONF_TRACE(client, "dropping dependency [%s]@%p because of collision", depbuf, dep);

                        pkgconf_dependency_unref(dep->owner, dep);
                        return NULL;
                }
                else if (dep2->flags && dep->flags == 0)
                {
                        PKGCONF_TRACE(client, "dropping dependency [%s]@%p because of collision", depbuf2, dep2);

                        pkgconf_node_delete(&dep2->iter, list);
                        pkgconf_dependency_unref(dep2->owner, dep2);
                }
                else
                        /* If both dependencies have equal strength, we keep both, because of situations like:
                         *    Requires: foo > 1, foo < 3
                         *
                         * If the situation is that both dependencies are literally equal, it is still harmless because
                         * fragment deduplication will handle the excessive fragments.
                         */
                        PKGCONF_TRACE(client, "keeping both dependencies (harmless)");
        }

        PKGCONF_TRACE(client, "added dependency [%s] to list @%p; flags=%x", dependency_to_str(dep, depbuf, sizeof depbuf), list, dep->flags);
        pkgconf_node_insert_tail(&dep->iter, pkgconf_dependency_ref(dep->owner, dep), list);

        /* This dependency is intentionally unowned.
         *
         * Internally we have no use for the returned type, and usually just
         * discard it. However, there is a publig pkgconf_dependency_add
         * function, which references this return value before returning it,
         * giving ownership at that point.
         */
        return dep;
}

static inline pkgconf_dependency_t *
pkgconf_dependency_addraw(pkgconf_client_t *client, pkgconf_list_t *list, const char *package, size_t package_sz, const char *version, size_t version_sz, pkgconf_pkg_comparator_t compare, unsigned int flags)
{
        pkgconf_dependency_t *dep;

        dep = calloc(1, sizeof(pkgconf_dependency_t));
        dep->package = pkgconf_strndup(package, package_sz);

        if (version_sz != 0)
                dep->version = pkgconf_strndup(version, version_sz);

        dep->compare = compare;
        dep->flags = flags;
        dep->owner = client;
        dep->refcount = 0;

        return add_or_replace_dependency_node(client, dep, list);
}

/*
 * !doc
 *
 * .. c:function:: pkgconf_dependency_t *pkgconf_dependency_add(pkgconf_list_t *list, const char *package, const char *version, pkgconf_pkg_comparator_t compare)
 *
 *    Adds a parsed dependency to a dependency list as a dependency node.
 *
 *    :param pkgconf_client_t* client: The client object that owns the package this dependency list belongs to.
 *    :param pkgconf_list_t* list: The dependency list to add a dependency node to.
 *    :param char* package: The package `atom` to set on the dependency node.
 *    :param char* version: The package `version` to set on the dependency node.
 *    :param pkgconf_pkg_comparator_t compare: The comparison operator to set on the dependency node.
 *    :param uint flags: Any flags to attach to the dependency node.
 *    :return: A dependency node.
 *    :rtype: pkgconf_dependency_t *
 */
pkgconf_dependency_t *
pkgconf_dependency_add(pkgconf_client_t *client, pkgconf_list_t *list, const char *package, const char *version, pkgconf_pkg_comparator_t compare, unsigned int flags)
{
        pkgconf_dependency_t *dep;
        dep = pkgconf_dependency_addraw(client, list, package, strlen(package), version,
                                        version != NULL ? strlen(version) : 0, compare, flags);
        return pkgconf_dependency_ref(dep->owner, dep);
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_dependency_append(pkgconf_list_t *list, pkgconf_dependency_t *tail)
 *
 *    Adds a dependency node to a pre-existing dependency list.
 *
 *    :param pkgconf_list_t* list: The dependency list to add a dependency node to.
 *    :param pkgconf_dependency_t* tail: The dependency node to add to the tail of the dependency list.
 *    :return: nothing
 */
void
pkgconf_dependency_append(pkgconf_list_t *list, pkgconf_dependency_t *tail)
{
        pkgconf_node_insert_tail(&tail->iter, tail, list);
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_dependency_free_one(pkgconf_dependency_t *dep)
 *
 *    Frees a dependency node.
 *
 *    :param pkgconf_dependency_t* dep: The dependency node to free.
 *    :return: nothing
 */
void
pkgconf_dependency_free_one(pkgconf_dependency_t *dep)
{
        if (dep->match != NULL)
                pkgconf_pkg_unref(dep->match->owner, dep->match);

        if (dep->package != NULL)
                free(dep->package);

        if (dep->version != NULL)
                free(dep->version);

        free(dep);
}

/*
 * !doc
 *
 * .. c:function:: pkgconf_dependency_t *pkgconf_dependency_ref(pkgconf_client_t *owner, pkgconf_dependency_t *dep)
 *
 *    Increases a dependency node's refcount.
 *
 *    :param pkgconf_client_t* owner: The client object which owns the memory of this dependency node.
 *    :param pkgconf_dependency_t* dep: The dependency to increase the refcount of.
 *    :return: the dependency node on success, else NULL
 */
pkgconf_dependency_t *
pkgconf_dependency_ref(pkgconf_client_t *client, pkgconf_dependency_t *dep)
{
        if (client != dep->owner)
                return NULL;

        dep->refcount++;
        PKGCONF_TRACE(client, "%s refcount@%p: %d", dep->package, dep, dep->refcount);
        return dep;
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_dependency_unref(pkgconf_client_t *owner, pkgconf_dependency_t *dep)
 *
 *    Decreases a dependency node's refcount and frees it if necessary.
 *
 *    :param pkgconf_client_t* owner: The client object which owns the memory of this dependency node.
 *    :param pkgconf_dependency_t* dep: The dependency to decrease the refcount of.
 *    :return: nothing
 */
void
pkgconf_dependency_unref(pkgconf_client_t *client, pkgconf_dependency_t *dep)
{
        if (client != dep->owner)
                return;

        --dep->refcount;
        PKGCONF_TRACE(client, "%s refcount@%p: %d", dep->package, dep, dep->refcount);

        if (dep->refcount <= 0)
                pkgconf_dependency_free_one(dep);
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_dependency_free(pkgconf_list_t *list)
 *
 *    Release a dependency list and its child dependency nodes.
 *
 *    :param pkgconf_list_t* list: The dependency list to release.
 *    :return: nothing
 */
void
pkgconf_dependency_free(pkgconf_list_t *list)
{
        pkgconf_node_t *node, *next;

        PKGCONF_FOREACH_LIST_ENTRY_SAFE(list->head, next, node)
        {
                pkgconf_dependency_t *dep = node->data;

                pkgconf_node_delete(&dep->iter, list);
                pkgconf_dependency_unref(dep->owner, dep);
        }

        pkgconf_list_zero(list);
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_dependency_parse_str(pkgconf_list_t *deplist_head, const char *depends)
 *
 *    Parse a dependency declaration into a dependency list.
 *    Commas are counted as whitespace to allow for constructs such as ``@SUBSTVAR@, zlib`` being processed
 *    into ``, zlib``.
 *
 *    :param pkgconf_client_t* client: The client object that owns the package this dependency list belongs to.
 *    :param pkgconf_list_t* deplist_head: The dependency list to populate with dependency nodes.
 *    :param char* depends: The dependency data to parse.
 *    :param uint flags: Any flags to attach to the dependency nodes.
 *    :return: nothing
 */
void
pkgconf_dependency_parse_str(pkgconf_client_t *client, pkgconf_list_t *deplist_head, const char *depends, unsigned int flags)
{
        parse_state_t state = OUTSIDE_MODULE;
        pkgconf_pkg_comparator_t compare = PKGCONF_CMP_ANY;
        char cmpname[PKGCONF_ITEM_SIZE];
        char buf[PKGCONF_BUFSIZE];
        size_t package_sz = 0, version_sz = 0;
        char *start = buf;
        char *ptr = buf;
        char *vstart = NULL;
        char *package = NULL, *version = NULL;
        char *cnameptr = cmpname;
        char *cnameend = cmpname + PKGCONF_ITEM_SIZE - 1;

        memset(cmpname, '\0', sizeof cmpname);

        pkgconf_strlcpy(buf, depends, sizeof buf);
        pkgconf_strlcat(buf, " ", sizeof buf);

        while (*ptr)
        {
                switch (state)
                {
                case OUTSIDE_MODULE:
                        if (!PKGCONF_IS_MODULE_SEPARATOR(*ptr))
                                state = INSIDE_MODULE_NAME;

                        break;

                case INSIDE_MODULE_NAME:
                        if (isspace((unsigned char)*ptr))
                        {
                                const char *sptr = ptr;

                                while (*sptr && isspace((unsigned char)*sptr))
                                        sptr++;

                                if (*sptr == '\0')
                                        state = OUTSIDE_MODULE;
                                else if (PKGCONF_IS_MODULE_SEPARATOR(*sptr))
                                        state = OUTSIDE_MODULE;
                                else if (PKGCONF_IS_OPERATOR_CHAR(*sptr))
                                        state = BEFORE_OPERATOR;
                                else
                                        state = OUTSIDE_MODULE;
                        }
                        else if (PKGCONF_IS_MODULE_SEPARATOR(*ptr))
                                state = OUTSIDE_MODULE;
                        else if (*(ptr + 1) == '\0')
                        {
                                ptr++;
                                state = OUTSIDE_MODULE;
                        }

                        if (state != INSIDE_MODULE_NAME && start != ptr)
                        {
                                char *iter = start;

                                while (PKGCONF_IS_MODULE_SEPARATOR(*iter))
                                        iter++;

                                package = iter;
                                package_sz = ptr - iter;
                                start = ptr;
                        }

                        if (state == OUTSIDE_MODULE)
                        {
                                pkgconf_dependency_addraw(client, deplist_head, package, package_sz, NULL, 0, compare, flags);

                                compare = PKGCONF_CMP_ANY;
                                package_sz = 0;
                        }

                        break;

                case BEFORE_OPERATOR:
                        if (PKGCONF_IS_OPERATOR_CHAR(*ptr))
                        {
                                state = INSIDE_OPERATOR;
                                if (cnameptr < cnameend)
                                        *cnameptr++ = *ptr;
                        }

                        break;

                case INSIDE_OPERATOR:
                        if (PKGCONF_IS_OPERATOR_CHAR(*ptr))
                        {
                                if (cnameptr < cnameend)
                                        *cnameptr++ = *ptr;
                                break;
                        }

                        state = AFTER_OPERATOR;
                        compare = pkgconf_pkg_comparator_lookup_by_name(cmpname);
                        // fallthrough

                case AFTER_OPERATOR:
                        if (!isspace((unsigned char)*ptr))
                        {
                                vstart = ptr;
                                state = INSIDE_VERSION;
                        }
                        break;

                case INSIDE_VERSION:
                        if (PKGCONF_IS_MODULE_SEPARATOR(*ptr) || *(ptr + 1) == '\0')
                        {
                                version = vstart;
                                version_sz = ptr - vstart;
                                state = OUTSIDE_MODULE;

                                pkgconf_dependency_addraw(client, deplist_head, package, package_sz, version, version_sz, compare, flags);

                                compare = PKGCONF_CMP_ANY;
                                cnameptr = cmpname;
                                memset(cmpname, 0, sizeof cmpname);
                                package_sz = 0;
                        }

                        if (state == OUTSIDE_MODULE)
                                start = ptr;
                        break;
                }

                ptr++;
        }
}

/*
 * !doc
 *
 * .. c:function:: void pkgconf_dependency_parse(const pkgconf_client_t *client, pkgconf_pkg_t *pkg, pkgconf_list_t *deplist, const char *depends)
 *
 *    Preprocess dependency data and then process that dependency declaration into a dependency list.
 *    Commas are counted as whitespace to allow for constructs such as ``@SUBSTVAR@, zlib`` being processed
 *    into ``, zlib``.
 *
 *    :param pkgconf_client_t* client: The client object that owns the package this dependency list belongs to.
 *    :param pkgconf_pkg_t* pkg: The package object that owns this dependency list.
 *    :param pkgconf_list_t* deplist: The dependency list to populate with dependency nodes.
 *    :param char* depends: The dependency data to parse.
 *    :param uint flags: Any flags to attach to the dependency nodes.
 *    :return: nothing
 */
void
pkgconf_dependency_parse(pkgconf_client_t *client, pkgconf_pkg_t *pkg, pkgconf_list_t *deplist, const char *depends, unsigned int flags)
{
        char *kvdepends = pkgconf_tuple_parse(client, &pkg->vars, depends, pkg->flags);

        pkgconf_dependency_parse_str(client, deplist, kvdepends, flags);
        free(kvdepends);
}

/*
 * !doc
 *
 * .. c:function:: pkgconf_dependency_t *pkgconf_dependency_copy(pkgconf_client_t *client, const pkgconf_dependency_t *dep)
 *
 *    Copies a dependency node to a new one.
 *
 *    :param pkgconf_client_t* client: The client object that will own this dependency.
 *    :param pkgconf_dependency_t* dep: The dependency node to copy.
 *    :return: a pointer to a new dependency node, else NULL
 */
pkgconf_dependency_t *
pkgconf_dependency_copy(pkgconf_client_t *client, const pkgconf_dependency_t *dep)
{
        pkgconf_dependency_t *new_dep;

        new_dep = calloc(1, sizeof(pkgconf_dependency_t));
        new_dep->package = strdup(dep->package);

        if (dep->version != NULL)
                new_dep->version = strdup(dep->version);

        new_dep->compare = dep->compare;
        new_dep->flags = dep->flags;
        new_dep->owner = client;
        new_dep->refcount = 0;

        if (dep->match != NULL)
                new_dep->match = pkgconf_pkg_ref(client, dep->match);

        return pkgconf_dependency_ref(client, new_dep);
}