// Copyright (C) 2022 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

#include <config.h>

#include <dhcpsrv/memfile_lease_limits.h>

using namespace isc::data;

namespace isc {
namespace dhcp {

size_t
ClassLeaseCounter::getClassCount(const ClientClass& client_class,
                                 const Lease::Type& ltype) const {
    const ClassCountMap& leases_by_class = getConstCountMap(ltype);
    auto it = leases_by_class.find(client_class);
    if (it == leases_by_class.end()) {
        return (0);
    }

    // Return the lease count for the class.
    return(it->second);
}

void
ClassLeaseCounter::setClassCount(const ClientClass& client_class, size_t count,
                                 const Lease::Type& ltype) {
    ClassCountMap& leases_by_class = getCountMap(ltype);
    leases_by_class[client_class] = count;
}

void
ClassLeaseCounter::adjustClassCount(const ClientClass& client_class, int offset,
                                    const Lease::Type& ltype) {
    ClassCountMap& leases_by_class = getCountMap(ltype);
    auto it = leases_by_class.find(client_class);
    if (it == leases_by_class.end()) {
        // Not there yet, add it.
        leases_by_class[client_class] = offset < 0 ? 0 : offset;
    } else {
        size_t new_count = it->second + offset;
        if (offset < 0 && (new_count > it->second)) {
            // We rolled over, set it zero.  We should probably log this?
            it->second = 0;
        } else {
            it->second = new_count;
        }
    }
}


ConstElementPtr
ClassLeaseCounter::getLeaseClientClasses(LeasePtr lease) {
    if (!lease) {
        isc_throw(BadValue, "getLeaseClientCLasses - lease cannot be empty");
    }

    ConstElementPtr classes;
    auto ctx = lease->getContext();
    try {
        if (ctx) {
            classes = ctx->find("ISC/client-classes");
            if (classes && classes->getType() != Element::list) {
                isc_throw(BadValue, "client-classes is not a list");
            }
        }
    } catch (const std::exception& ex) {
        isc_throw(BadValue, "getLeaseClientClasses - invalid context: "
                  << data::prettyPrint(ctx) << ", " << ex.what());
    }

    return (classes);
}

void
ClassLeaseCounter::adjustClassCounts(ConstElementPtr classes, int offset,
                                     const Lease::Type& ltype) {
    if (!classes) {
        return;
    }

    for (int i = 0; i < classes->size(); ++i) {
        std::string class_name = classes->get(i)->stringValue();
        adjustClassCount(class_name, offset, ltype);
    }
}

void
ClassLeaseCounter::addLease(LeasePtr lease) {
    if (!lease) {
        isc_throw(BadValue, "addLease - lease cannot be empty");
    }

    ConstElementPtr classes = getLeaseClientClasses(lease);
    if (!classes) {
        return; // Lease limits isn't loaded.
    }

    // Add the new lease to its classes.
    if (lease->state_ == Lease::STATE_DEFAULT) {
        adjustClassCounts(classes, 1, lease->getType());
    }
}

void
ClassLeaseCounter::updateLease(LeasePtr new_lease, LeasePtr old_lease) {
    // Sanity checks.
    if (!new_lease) {
        isc_throw(BadValue, "updateLease - new_lease cannot be empty");
    }

    if (!old_lease) {
        isc_throw(BadValue, "updateLease - old_lease cannot be empty");
    }

    ConstElementPtr new_classes = getLeaseClientClasses(new_lease);
    uint32_t new_state = new_lease->state_;

    ConstElementPtr old_classes = getLeaseClientClasses(old_lease);
    uint32_t old_state = old_lease->state_;

    // Did we change states or classes?
    // Note we do not worry about lease type changes, because it makes no
    // business sense to repurpose a lease as a different type. Other than
    // some unit tests unrelated to this it never occurs in the code.
    if ((old_state != new_state) || (old_classes != new_classes)) {
        // Old classes are moving out of a counted state.
        if (old_state == Lease::STATE_DEFAULT) {
            adjustClassCounts(old_classes, -1, old_lease->getType());
        }

        // New classes are moving into a counted state.
        if (new_state == Lease::STATE_DEFAULT) {
            adjustClassCounts(new_classes, 1, new_lease->getType());
        }
    }
}

void
ClassLeaseCounter::removeLease(LeasePtr lease) {
    if (!lease) {
        isc_throw(BadValue, "removeLease - lease cannot be empty");
    }

    ConstElementPtr classes = getLeaseClientClasses(lease);
    if (!classes) {
        return; // Lease limits isn't loaded.
    }

    // Remove the new lease to its classes.
    if (lease->state_ == Lease::STATE_DEFAULT) {
        adjustClassCounts(classes, -1, lease->getType());
    }
}

} // end of isc::dhcp namespace
} // end of isc namespace