/* See the DRL-LICENSE file for this file's software license. */

#include <arpa/inet.h>
#include <dirent.h>
#include <errno.h>
#include <libxml/xmlmemory.h>
#include <libxml/parser.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>

#include "raterouter.h"
#include "ratetypes.h"
#include "config.h"
#include "util.h"
#include "logging.h"

void free_ident(ident_config *ident) {
    /* Free peers. */
    while (ident->peers) {
        ident_peer *tofree = ident->peers;
        ident->peers = ident->peers->next;
        free(tofree);
    }

    /* Free members. */
    while (ident->members) {
        ident_member *tofree = ident->members;
        ident->members = ident->members->next;
        free(tofree);
    }

    /* Free ident. */
    free(ident);
}

void free_ident_list(ident_config *list) {
    ident_config *tofree;

    while (list) {
        tofree = list;
        list = list->next;
        free_ident(tofree);
    }
}

static int xid_filter(const struct dirent *d) {
    if (atoi(d->d_name) > 0)
        return 1;
    else
        return 0;
}

int get_eligible_leaves(drl_instance_t *instance) {
    struct dirent **names;
    int count, i;
    leaf_t *leaves = NULL;
    map_handle leaf_map = allocate_map();

    if (leaf_map == NULL) {
        return ENOMEM;
    }

    count = scandir("/proc/virtual", &names, xid_filter, alphasort);

    if (count < 1) {
        return 1;
    }

    leaves = malloc(count * sizeof(leaf_t));
    if (leaves == NULL) {
        /* Couldn't allocate leaves array.  Need to free names memory. */
        while (count--) {
            free(names[count]);
        }
        free(names);

        return ENOMEM;
    }
    memset(leaves, 0, count * sizeof(leaf_t));

    for (i = 0; i < count; ++i) {
        leaves[i].xid = atoi(names[i]->d_name);
        leaves[i].parent = NULL;
        leaves[i].drop_prob = 0.0;
        leaves[i].delay = 0;
        
        free(names[i]);

        map_insert(leaf_map, &leaves[i].xid, sizeof(leaves[i].xid), &leaves[i]);
    }

    free(names);

    instance->leaf_map = leaf_map;
    instance->leaves = leaves;
    instance->leaf_count = count;

    return 0;
}

int parse_leaves(drl_instance_t *instance, char *leafstring) {
    int count = 1;
    int i;
    char *comma = leafstring;
    leaf_t *leaves = NULL;
    map_handle leaf_map;
    
    while ((comma = strchr(comma, ',')) != NULL) {
        count += 1;
        comma++;
    }

    leaf_map = allocate_map();
    if (leaf_map == NULL) {
        return ENOMEM;
    }

    leaves = malloc(count * sizeof(leaf_t));
    if (leaves == NULL) {
        return ENOMEM;
    }
    memset(leaves, 0, count * sizeof(leaf_t));

    comma = leafstring;
    for (i = 0; i < count; ++i) {
        leaves[i].xid = (uint32_t) strtol(comma, NULL, 16);
        leaves[i].parent = NULL;
        leaves[i].drop_prob = 0.0;
        leaves[i].delay = 0;

        printlog(LOG_DEBUG, "Read leaf - hex: %x, dec: %d\n", leaves[i].xid, leaves[i].xid);

        comma = strchr(comma, ',');
        comma++;
    }

    instance->leaf_map = leaf_map;
    instance->leaves = leaves;
    instance->leaf_count = count;

    return 0;
}

static int parse_common(xmlDocPtr doc, xmlNodePtr ident, ident_config *common) {
    xmlChar *id;
    xmlChar *limit;
    xmlChar *commfabric;
    xmlChar *branch;
    xmlChar *membership;
    xmlChar *failure_behavior;
    xmlChar *accounting;
    xmlChar *ewma;
    xmlChar *mainloop_intervals;
    xmlChar *communication_intervals;
    xmlChar *independent;
    xmlChar *htb_node;
    xmlChar *htb_parent;
    xmlNodePtr fields = ident->children;
    ident_peer *current = NULL;

    /* The struct has been memsetted to 0, this is just to be safe. */
#ifdef BUILD_ZOOKEEPER
    common->zk_host = NULL;
#endif
    common->peers = NULL;
    common->members = NULL;
    common->next = NULL;

    /* Make sure no required fields are missing. */
    id = xmlGetProp(ident, (const xmlChar *) "id");
    if (id == NULL) {
        printlog(LOG_CRITICAL, "Ident missing globally unique identifier.\n");
        return EINVAL;
    } else {
        common->id = atoi((const char *) id);
        xmlFree(id);
    }

    limit = xmlGetProp(ident, (const xmlChar *) "limit");
    if (limit == NULL) {
        printlog(LOG_CRITICAL, "Ident missing global rate limit.\n");
        return EINVAL;
    } else {
        common->limit = atoi((const char *) limit);
        xmlFree(limit);
    }

    commfabric = xmlGetProp(ident, (const xmlChar *) "commfabric");
    if (commfabric == NULL) {
        printlog(LOG_CRITICAL, "Ident missing comm fabric specifier.\n");
        return EINVAL;
    } else {
        if (!xmlStrcmp(commfabric, (const xmlChar *) "MESH")) {
            common->commfabric = COMM_MESH;
        } else if (!xmlStrcmp(commfabric, (const xmlChar *) "GOSSIP")) {
            common->commfabric = COMM_GOSSIP;
        } else {
            printlog(LOG_CRITICAL, "Unknown/invalid comm fabric.\n");
            xmlFree(commfabric);
            return EINVAL;
        }
        xmlFree(commfabric);
    }

    /* Only care about branching factor and failure detector if we're using gossip. */
    if (common->commfabric == COMM_GOSSIP) {
        branch = xmlGetProp(ident, (const xmlChar *) "branch");
        if (branch == NULL) {
            printlog(LOG_CRITICAL, "Ident missing gossip branch.\n");
            return EINVAL;
        } else {
            common->branch = atoi((const char *) branch);
            xmlFree(branch);
        }

        membership = xmlGetProp(ident, (const xmlChar *) "membership");
        if (membership == NULL) {
            printlog(LOG_CRITICAL, "Ident missing membership protocol selection.\n");
            return EINVAL;
        } else {
            if (!xmlStrcmp(membership, (const xmlChar *) "SWIM")) {
                common->membership = SWIM;
            } else if (!xmlStrcmp(membership, (const xmlChar *) "ZOOKEEPER")) {
#ifdef BUILD_ZOOKEEPER
                common->membership = ZOOKEEPER;
#else
                printlog(LOG_CRITICAL, "Zookeeper requested, but support not compiled into DRL at configure time.\n");
                xmlFree(membership);
                return EINVAL;
#endif
            } else {
                printlog(LOG_CRITICAL, "Unknown/invalid gossip group membership protocol.\n");
                xmlFree(membership);
                return EINVAL;
            }
            xmlFree(membership);
        }

        failure_behavior = xmlGetProp(ident, (const xmlChar *) "failure_behavior");
        if (failure_behavior == NULL) {
            printlog(LOG_CRITICAL, "Ident missing failure handling behavior.\n");
            return EINVAL;
        } else {
            if (!xmlStrcmp(failure_behavior, (const xmlChar *) "PANIC")) {
                common->failure_behavior = PANIC;
            } else if (!xmlStrcmp(failure_behavior, (const xmlChar *) "QUORUM")) {
                common->failure_behavior = QUORUM;
            } else {
                printlog(LOG_CRITICAL, "Unknown/invalid gossip failure behavior policy.\n");
                xmlFree(failure_behavior);
                return EINVAL;
            }
            xmlFree(failure_behavior);
        }
    }

    accounting = xmlGetProp(ident, (const xmlChar *) "accounting");
    if (accounting == NULL) {
        printlog(LOG_CRITICAL, "Ident missing accounting.\n");
        return EINVAL;
    } else {
        if (!xmlStrcmp(accounting, (const xmlChar *) "STANDARD")) {
            common->accounting = ACT_STANDARD;
        } else if (!xmlStrcmp(accounting, (const xmlChar *) "SAMPLEHOLD")) {
            common->accounting = ACT_SAMPLEHOLD;
        } else if (!xmlStrcmp(accounting, (const xmlChar *) "SIMPLE")) {
            common->accounting = ACT_SIMPLE;
        } else if (!xmlStrcmp(accounting, (const xmlChar *) "MULTIPLEINTERVAL")) {
            common->accounting = ACT_MULTIPLE;
        } else {
            printlog(LOG_CRITICAL, "Unknown/invalid accounting table.\n");
            xmlFree(accounting);
            return EINVAL;
        }
        xmlFree(accounting);
    }

    ewma = xmlGetProp(ident, (const xmlChar *) "ewma");
    if (ewma == NULL) {
        printlog(LOG_CRITICAL, "Ident missing ewma weight.\n");
        return EINVAL;
    } else {
        common->fixed_ewma_weight = atof((const char *) ewma);
        xmlFree(ewma);
    }

    mainloop_intervals = xmlGetProp(ident, (const xmlChar *) "loop_intervals");
    if (mainloop_intervals == NULL) {
        printlog(LOG_WARN, "Ident id: %d missing loop_intervals, assuming 1.\n", common->id);
        common->mainloop_intervals = 1;
    } else {
        common->mainloop_intervals = atoi((const char *) mainloop_intervals);
        xmlFree(mainloop_intervals);
    }

    communication_intervals = xmlGetProp(ident, (const xmlChar *) "comm_intervals");
    if (communication_intervals == NULL) {
        printlog(LOG_WARN, "Ident id: %d missing comm_intervals, assuming 1.\n", common->id);
        common->communication_intervals = 1;
    } else {
        common->communication_intervals = atoi((const char *) communication_intervals);
        xmlFree(communication_intervals);
    }

    independent = xmlGetProp(ident, (const xmlChar *) "independent");
    if (independent == NULL) {
        common->independent = 0;
    } else {
        common->independent = atoi((const char *) independent);
        xmlFree(independent);
    }

    htb_node = xmlGetProp(ident, (const xmlChar *) "htb_node");
    htb_parent = xmlGetProp(ident, (const xmlChar *) "htb_parent");
    if (htb_node == NULL) {
        common->htb_node = -1;
    } else {
        sscanf((const char *)htb_node, "%x", &common->htb_node);
        xmlFree(htb_node);
    }
    if (htb_parent == NULL) {
        common->htb_parent = -1;
    } else {
        sscanf((const char *)htb_parent, "%x", &common->htb_parent);
        xmlFree(htb_parent);
    }

    while (fields != NULL) {
        if((!xmlStrcmp(fields->name, (const xmlChar *) "peer"))) {
            xmlChar *ip = xmlNodeListGetString(doc, fields->children, 1);
            if (current == NULL) {
                /* No peers yet. */
                common->peers = malloc(sizeof(ident_peer));
                if (common->peers == NULL) {
                    return ENOMEM;
                }
                common->peers->ip = inet_addr((const char *) ip);
                common->peers->next = NULL;
                common->peer_count += 1;
                current = common->peers;
            } else {
                /* Add it to the list. */
                current->next = malloc(sizeof(ident_peer));
                if (current->next == NULL) {
                    return ENOMEM;
                }
                current = current->next;
                current->ip = inet_addr((const char *) ip);
                common->peer_count += 1;
                current->next = NULL;
            }
            xmlFree(ip);
        } else if ((!xmlStrcmp(fields->name, (const xmlChar *) "zkhost"))) {
            xmlChar *host = xmlNodeListGetString(doc, fields->children, 1);

#ifdef BUILD_ZOOKEEPER
            common->zk_host = strdup((const char *) host);
            if (common->zk_host == NULL) {
                return ENOMEM;
            }
#endif
            xmlFree(host);
        }
        fields = fields->next;
    }

    if (common->peers == NULL) {
        printlog(LOG_CRITICAL, "Must have at least one peer.\n");
        return EINVAL;
    }

#ifdef BUILD_ZOOKEEPER
    if (common->membership == ZOOKEEPER && common->zk_host == NULL) {
        printlog(LOG_CRITICAL, "Group membership protocol ZOOKEEPER requires a zkhost field.\n");
        return EINVAL;
    }
#endif
    /* No errors. */
    return 0;
}

static ident_config *parse_machine(xmlDocPtr doc, xmlNodePtr ident, parsed_configs *configs) {
    ident_config *common = malloc(sizeof(ident_config));

    if (common == NULL) {
        return NULL;
    }

    memset(common, 0, sizeof(ident_config));
    if (parse_common(doc, ident, common)) {
        free_ident(common);
        return NULL;
    }

    /* No further information needed for machine-level identities. */
    common->type = IDENT_MACHINE;
    common->members = NULL;
    common->next = NULL;

    if (configs->last_machine == NULL) {
        configs->machines = common;
        configs->last_machine = common;
    } else {
        configs->last_machine->next = common;
        configs->last_machine = common;
    }

    configs->machine_count += 1;

    return common;
}

static ident_config *parse_set(xmlDocPtr doc, xmlNodePtr ident, parsed_configs *configs) {
    xmlNodePtr fields = ident->children;
    ident_config *common = malloc(sizeof(ident_config));
    ident_member *current = NULL;

    if (common == NULL) {
        return NULL;
    }

    memset(common, 0, sizeof(ident_config));
    if (parse_common(doc, ident, common)) {
        free_ident(common);
        return NULL;
    }

    while (fields != NULL) {
        ident_member *member = NULL;

        if (!xmlStrcmp(fields->name, (const xmlChar *) "xid")) {
            xmlChar *xid = xmlNodeListGetString(doc, fields->children, 1);

            if (atoi((const char *) xid) >= 0) {
                member = malloc(sizeof(ident_member));
                if (member == NULL) {
                    free_ident(common);
                    xmlFree(xid);
                    return NULL;
                }
                member->type = MEMBER_XID;
                sscanf((const char *) xid, "%x", &member->value);
                member->next = NULL;
            } else {
                free_ident(common);
                xmlFree(xid);
                return NULL;
            }

            xmlFree(xid);
        } else if (!xmlStrcmp(fields->name, (const xmlChar *) "guid")) {
            xmlChar *guid = xmlNodeListGetString(doc, fields->children, 1);

            if (atoi((const char *) guid) >= 0) {
                member = malloc(sizeof(ident_member));
                if (member == NULL) {
                    free_ident(common);
                    xmlFree(guid);
                    return NULL;
                }
                member->type = MEMBER_GUID;
                member->value = atoi((const char *) guid);
                member->next = NULL;
            } else {
                free_ident(common);
                xmlFree(guid);
                return NULL;
            }

            xmlFree(guid);
        }

        if (member) {
            if (common->members == NULL) {
                common->members = member;
                current = member;
            } else {
                current->next = member;
                current = member;
            }
        }

        fields = fields->next;
    }

    /* A sliver set must have at least one member (xid or guid) or else it is
     * meaningless. */
    if (common->members == NULL) {
        free_ident(common);
        return NULL;
    }

    common->type = IDENT_SET;
    common->next = NULL;

    if (configs->last_set == NULL) {
        configs->sets = common;
        configs->last_set = common;
    } else {
        configs->last_set->next = common;
        configs->last_set = common;
    }

    configs->set_count += 1;

    return common;
}

int parse_drl_config(const char *configfile, parsed_configs *configs) {
    xmlDocPtr doc;
    xmlNodePtr drl, ident;

    configs->machines = NULL;
    configs->sets = NULL;
    configs->last_machine = NULL;
    configs->last_set = NULL;
    configs->machine_count = 0;
    configs->set_count = 0;

    if(!(doc = xmlParseFile(configfile))){
        printlog(LOG_CRITICAL, "Config file (%s) not parsed successfully.\n", configfile);
        xmlFreeDoc(doc);
        return EIO;
    }

    if(!(drl = xmlDocGetRootElement(doc))){
        printlog(LOG_CRITICAL, "Config file (%s) has no root element.\n", configfile);
        xmlFreeDoc(doc);
        return EIO;
    }
    if(xmlStrcmp(drl->name, (const xmlChar *) "drl")){
        printlog(LOG_CRITICAL, "Config file (%s) of the wrong type, root node != drl\n", configfile);
        xmlFreeDoc(doc);
        return EIO;
    }

    ident = drl->children;
    while(ident != NULL) {
        ident_config *new = NULL;

        if((!xmlStrcmp(ident->name, (const xmlChar *) "machine"))) {
            new = parse_machine(doc, ident, configs);
        } else if ((!xmlStrcmp(ident->name, (const xmlChar *) "set"))) {
            new = parse_set(doc, ident, configs);
        } else if ((!xmlStrcmp(ident->name, (const xmlChar *) "text"))) {
            /* libxml seems to wrap everything inside two 'text's. */
            ident = ident->next;
            continue;
        }

        if (new == NULL) {
            /* FIXME: Make this more descriptive. :) */
            printlog(LOG_CRITICAL, "Error occurred while parsing...\n");

            free_ident_list(configs->machines);
            free_ident_list(configs->sets);

            configs->machines = NULL;
            configs->sets = NULL;
            configs->last_machine = NULL;
            configs->last_set = NULL;

            xmlFreeDoc(doc);
            return 1;
        }

        ident = ident->next;
    }

    xmlFreeDoc(doc);

    /* Return the list of parsed identities. */
    return 0;
}