mouse_events.cpp

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/* $Id: mouse_events.cpp 54160 2012-05-12 17:06:13Z jamit $ */
/*
   Copyright (C) 2006 - 2012 by Joerg Hinrichs <joerg.hinrichs@alice-dsl.de>
   wesnoth playturn Copyright (C) 2003 by David White <dave@whitevine.net>
   Part of the Battle for Wesnoth Project http://www.wesnoth.org/

   This program 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 2 of the License, or
   (at your option) any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY.

   See the COPYING file for more details.
*/

#include "global.hpp"

#include "mouse_events.hpp"

#include "actions.hpp"
#include "attack_prediction_display.hpp"
#include "dialogs.hpp"
#include "foreach.hpp"
#include "game_end_exceptions.hpp"
#include "game_events.hpp"
#include "gettext.hpp"
#include "gui/dialogs/unit_attack.hpp"
#include "gui/widgets/settings.hpp"
#include "gui/dialogs/transient_message.hpp"
#include "gui/widgets/window.hpp"
#include "language.hpp"
#include "log.hpp"
#include "map.hpp"
#include "marked-up_text.hpp"
#include "menu_events.hpp"
#include "pathfind/teleport.hpp"
#include "play_controller.hpp"
#include "sound.hpp"
#include "replay.hpp"
#include "resources.hpp"
#include "rng.hpp"
#include "tod_manager.hpp"
#include "wml_separators.hpp"
#include "whiteboard/manager.hpp"

#include <boost/bind.hpp>

static lg::log_domain log_engine("engine");
#define ERR_NG LOG_STREAM(err, log_engine)
#define LOG_NG LOG_STREAM(info, log_engine)

namespace events{


mouse_handler::mouse_handler(game_display* gui, std::vector<team>& teams,
        unit_map& units, gamemap& map, tod_manager& tod_mng) :
    mouse_handler_base(),
    map_(map),
    gui_(gui),
    teams_(teams),
    units_(units),
    tod_manager_(tod_mng),
    previous_hex_(),
    previous_free_hex_(),
    selected_hex_(),
    next_unit_(),
    current_route_(),
    current_paths_(),
    enemy_paths_(false),
    path_turns_(0),
    side_num_(1),
    undo_(false),
    over_route_(false),
    reachmap_invalid_(false),
    show_partial_move_(false)
{
    singleton_ = this;
}

mouse_handler::~mouse_handler()
{
    rand_rng::clear_new_seed_callback();
    singleton_ = NULL;
}

void mouse_handler::set_side(int side_number)
{
    side_num_ = side_number;
}

int mouse_handler::drag_threshold() const
{
    return 14;
}

void mouse_handler::mouse_motion(int x, int y, const bool browse, bool update, map_location new_hex)
{
    // we ignore the position coming from event handler
    // because it's always a little obsolete and we don't need
    // to hightlight all the hexes where the mouse passed.
    // Also, sometimes it seems to have one *very* obsolete
    // and isolated mouse motion event when using drag&drop
    SDL_GetMouseState(&x,&y);  // <-- modify x and y

    if (mouse_handler_base::mouse_motion_default(x, y, update)) return;

    if (new_hex == map_location::null_location)
        new_hex = gui().hex_clicked_on(x,y);

    if(new_hex != last_hex_) {
        update = true;
        if (last_hex_.valid()) {
            // we store the previous hexes used to propose attack direction
            previous_hex_ = last_hex_;
            // the hex of the selected unit is also "free"
            { // start planned unit map scope
                wb::future_map_if_active raii;
                if (last_hex_ == selected_hex_ || find_unit(last_hex_) == units_.end()) {
                    previous_free_hex_ = last_hex_;
                }
            } // end planned unit map scope
        }
        last_hex_ = new_hex;
    }


    if (reachmap_invalid_) update = true;

    if (update) {
        if (reachmap_invalid_) {
            reachmap_invalid_ = false;
            if (!current_paths_.destinations.empty() && !show_partial_move_) {
                bool selected_hex_has_unit;
                { // start planned unit map scope
                    wb::future_map_if_active planned_unit_map;
                    selected_hex_has_unit = find_unit(selected_hex_) != units_.end();
                } // end planned unit map scope
                if(selected_hex_.valid() && selected_hex_has_unit ) {
                    // reselect the unit without firing events (updates current_paths_)
                    select_hex(selected_hex_, true);
                }
                // we do never deselect here, mainly because of canceled attack-move
            }
        }

        // reset current_route_ and current_paths if not valid anymore
        // we do it before cursor selection, because it uses current_paths_
        if(new_hex.valid() == false) {
            current_route_.steps.clear();
            gui().set_route(NULL);
            resources::whiteboard->erase_temp_move();
        }

        if(enemy_paths_) {
            enemy_paths_ = false;
            current_paths_ = pathfind::paths();
            gui().unhighlight_reach();
        } else if(over_route_) {
            over_route_ = false;
            current_route_.steps.clear();
            gui().set_route(NULL);
            resources::whiteboard->erase_temp_move();
        }

        gui().highlight_hex(new_hex);
        resources::whiteboard->on_mouseover_change(new_hex);

        unit_map::iterator selected_unit;
        unit_map::iterator mouseover_unit;
        map_location attack_from;

        { // start planned unit map scope
            wb::future_map_if_active planned_unit_map;
            selected_unit = find_unit(selected_hex_);
            mouseover_unit = find_unit(new_hex);

            // we search if there is an attack possibility and where
            attack_from = current_unit_attacks_from(new_hex);

            //see if we should show the normal cursor, the movement cursor, or
            //the attack cursor
            //If the cursor is on WAIT, we don't change it and let the setter
            //of this state end it
            if (cursor::get() != cursor::WAIT) {
                if (selected_unit != units_.end() &&
                    selected_unit->side() == side_num_ &&
                    !selected_unit->incapacitated() && !browse)
                {
                    if (attack_from.valid()) {
                        cursor::set(dragging_started_ ? cursor::ATTACK_DRAG : cursor::ATTACK);
                    }
                    else if (mouseover_unit==units_.end() &&
                             current_paths_.destinations.contains(new_hex))
                    {
                        cursor::set(dragging_started_ ? cursor::MOVE_DRAG : cursor::MOVE);
                    } else {
                        // selected unit can't attack or move there
                        cursor::set(cursor::NORMAL);
                    }
                } else {
                    // no selected unit or we can't move it
                    cursor::set(cursor::NORMAL);
                }
            }
        } // end planned unit map scope

        // show (or cancel) the attack direction indicator
        if (attack_from.valid() && (!browse || resources::whiteboard->is_active())) {
            gui().set_attack_indicator(attack_from, new_hex);
        } else {
            gui().clear_attack_indicator();
        }

        unit* un; //will later point to unit at mouseover_hex_

        // the destination is the pointed hex or the adjacent hex
        // used to attack it
        map_location dest;
        unit_map::const_iterator dest_un;
        { // start planned unit map scope
            wb::future_map_if_active raii;
            if (attack_from.valid()) {
                dest = attack_from;
                dest_un = find_unit(dest);
            }   else {
                dest = new_hex;
                dest_un = find_unit(new_hex);
            }

            if(dest == selected_hex_ || dest_un != units_.end()) {
                current_route_.steps.clear();
                gui().set_route(NULL);
                resources::whiteboard->erase_temp_move();
            }
            else if (!current_paths_.destinations.empty() &&
                     map_.on_board(selected_hex_) && map_.on_board(new_hex))
            {
                if (selected_unit != units_.end() && !selected_unit->incapacitated()) {
                    // Show the route from selected unit to mouseover hex
                    current_route_ = get_route(&*selected_unit, dest, viewing_team());

                    resources::whiteboard->create_temp_move();

                    if(!browse) {
                        gui().set_route(&current_route_);
                    }
                }
            }

            unit_map::iterator iter = mouseover_unit;
            if (iter != units_.end())
                un = &*iter;
            else
                un = NULL;
        } //end planned unit map scope

        if (un && current_paths_.destinations.empty() &&
            !gui().fogged(un->get_location()))
        {
            if (un->side() != side_num_) {
                //unit under cursor is not on our team, highlight reach
                //Note: planned unit map must be activated after this is done,
                //since the future state includes changes to units' movement.
                unit_movement_resetter move_reset(*un);


                { // start planned unit map scope
                    wb::future_map_if_active raii;
                    current_paths_ = pathfind::paths(map_,units_,*un,teams_,
                                                        false,true,viewing_team(),path_turns_);
                } // end planned unit map scope

                gui().highlight_reach(current_paths_);
                enemy_paths_ = true;
            } else {
                //unit is on our team, show path if the unit has one
                const map_location go_to = un->get_goto();
                if(map_.on_board(go_to)) {
                    pathfind::marked_route route;
                    { // start planned unit map scope
                        wb::future_map_if_active raii;
                        route = get_route(un, go_to, current_team());
                    } // end planned unit map scope
                    gui().set_route(&route);
                }
                over_route_ = true;
            }
        }
    }
}

unit_map::iterator mouse_handler::selected_unit()
{
    unit_map::iterator res = find_unit(selected_hex_);
    if(res != units_.end()) {
        return res;
    } else {
        return find_unit(last_hex_);
    }
}

unit_map::iterator mouse_handler::find_unit(const map_location& hex)
{
    unit_map::iterator it = find_visible_unit(hex, viewing_team());
    if (it.valid())
        return it;
    else
        return resources::units->end();
}

unit_map::const_iterator mouse_handler::find_unit(const map_location& hex) const
{
    return find_visible_unit(hex, viewing_team());
}

map_location mouse_handler::current_unit_attacks_from(const map_location& loc) const
{
    if(loc == selected_hex_)
        return map_location();

    bool wb_active = resources::whiteboard->is_active();

    {
        // Check the unit SOURCE of the attack

        // Check that there's a selected unit
        const unit_map::const_iterator source_unit = find_unit(selected_hex_);
        bool source_eligible = (source_unit != units_.end());
        if (!source_eligible) return map_location();

        // The selected unit must at least belong to the player currently controlling this client.
        source_eligible &= source_unit->side() == resources::screen->viewing_side();
        if (!source_eligible) return map_location();

        // In addition:
        // - If whiteboard is enabled, we allow planning attacks outside of player's turn
        // - If whiteboard is disabled, it must be the turn of the player controlling this client
        if(!wb_active) {
            source_eligible &= resources::screen->viewing_side() == resources::controller->current_side();
            if (!source_eligible) return map_location();
        }

        // Unit must have attacks left
        source_eligible &= source_unit->attacks_left() != 0;
        if (!source_eligible) return map_location();


        // Check the unit TARGET of the attack

        team const& viewing_team = (*resources::teams)[resources::screen->viewing_team()];

        // Check that there's a unit at the target location
        const unit_map::const_iterator target_unit = find_unit(loc);
        bool target_eligible = (target_unit != units_.end());
        if (!target_eligible) return map_location();

        // The player controlling this client must be an enemy of the target unit's side
        target_eligible &= viewing_team.is_enemy(target_unit->side());
        if (!target_eligible) return map_location();

        // Sanity check: source and target of the attack shouldn't be on the same team
        assert(source_unit->side() != target_unit->side());

        target_eligible &= !target_unit->incapacitated();
        if (!target_eligible) return map_location();
    }

    const map_location::DIRECTION preferred = loc.get_relative_dir(previous_hex_);
    const map_location::DIRECTION second_preferred = loc.get_relative_dir(previous_free_hex_);

    int best_rating = 100;//smaller is better
    map_location res;
    map_location adj[6];
    get_adjacent_tiles(loc,adj);

    for(size_t n = 0; n != 6; ++n) {
        if(map_.on_board(adj[n]) == false) {
            continue;
        }

        if(adj[n] != selected_hex_ && find_unit(adj[n]) != units_.end()) {
            continue;
        }

        if (current_paths_.destinations.contains(adj[n]))
        {
            static const size_t NDIRECTIONS = map_location::NDIRECTIONS;
            unsigned int difference = abs(int(preferred - n));
            if(difference > NDIRECTIONS/2) {
                difference = NDIRECTIONS - difference;
            }
            unsigned int second_difference = abs(int(second_preferred - n));
            if(second_difference > NDIRECTIONS/2) {
                second_difference = NDIRECTIONS - second_difference;
            }
            const int rating = difference * 2 + (second_difference > difference);
            if(rating < best_rating || res.valid() == false) {
                best_rating = rating;
                res = adj[n];
            }
        }
    }

    return res;
}

pathfind::marked_route mouse_handler::get_route(unit* un, map_location go_to, team &team)
{
    // The pathfinder will check unit visibility (fogged/stealthy).
    const pathfind::shortest_path_calculator calc(*un, team, units_, teams_, map_);

    pathfind::teleport_map allowed_teleports = pathfind::get_teleport_locations(*un, viewing_team());

    pathfind::plain_route route;

    route = pathfind::a_star_search(un->get_location(), go_to, 10000.0, &calc, map_.w(), map_.h(), &allowed_teleports);

    return mark_route(route);
}

void mouse_handler::mouse_press(const SDL_MouseButtonEvent& event, const bool browse)
{
    mouse_handler_base::mouse_press(event, browse);
}

bool mouse_handler::right_click_show_menu(int x, int y, const bool browse)
{
    // The first right-click cancel the selection if any,
    // the second open the context menu
    unit_map::iterator unit;
    {
        wb::future_map_if_active raii;
        unit = find_unit(selected_hex_);
    }
    if (selected_hex_.valid() && unit != units_.end()) {
        select_hex(map_location(), browse);
        return false;
    } else {
        return point_in_rect(x, y, gui().map_area());
    }
}

bool mouse_handler::left_click(int x, int y, const bool browse)
{
    undo_ = false;
    if (mouse_handler_base::left_click(x, y, browse)) return false;

    // Lock whiteboard activation state to avoid problems due to
    // its changing while an animation takes place.
    wb::whiteboard_lock wb_lock = resources::whiteboard->get_activation_state_lock();

    //we use the last registered highlighted hex
    //since it's what update our global state
    map_location hex = last_hex_;

    unit_map::iterator u;
    unit_map::iterator clicked_u;
    map_location src;
    pathfind::paths orig_paths;
    map_location attack_from;
    { // start planned unit map scope
        wb::future_map_if_active planned_unit_map;
        u = find_unit(selected_hex_);

        //if the unit is selected and then itself clicked on,
        //any goto command is cancelled
        if (u != units_.end() && !browse && selected_hex_ == hex && u->side() == side_num_) {
            u->set_goto(map_location());
        }

        clicked_u = find_unit(hex);

        src = selected_hex_;
        orig_paths = current_paths_;
        attack_from = current_unit_attacks_from(hex);
    } // end planned unit map scope

    //see if we're trying to do a attack or move-and-attack
    if((!browse || resources::whiteboard->is_active()) && !commands_disabled && attack_from.valid()) {

        if (((u.valid() && u->side() == side_num_) || resources::whiteboard->is_active()) && clicked_u.valid() ) {
            if (attack_from == selected_hex_) { //no move needed
                int choice = -1;
                { wb::future_map_if_active planned_unit_map; //start planned unit map scope
                    choice = show_attack_dialog(attack_from, clicked_u->get_location());
                } // end planned unit map scope
                if (choice >=0 ) {
                    if (resources::whiteboard->is_active()) {
                        save_whiteboard_attack(attack_from, clicked_u->get_location(), choice);
                    } else {
                        attack_enemy(u->get_location(), clicked_u->get_location(), choice);
                    }
                }
                return false;
            }
            else {

                int choice = -1; //for the attack dialog

                { wb::future_map_if_active planned_unit_map; //start planned unit map scope
                    // we will now temporary move next to the enemy
                    pathfind::paths::dest_vect::const_iterator itor =
                            current_paths_.destinations.find(attack_from);
                    if(itor == current_paths_.destinations.end()) {
                        // can't reach the attacking location
                        // not supposed to happen, so abort
                        return false;
                    }
                    // update movement_left as if we did the move
                    int move_left_dst = itor->move_left;
                    int move_left_src = u->movement_left();
                    u->set_movement(move_left_dst);

                    // block where we temporary move the unit
                    {
                        temporary_unit_mover temp_mover(units_, src, attack_from);

                            choice = show_attack_dialog(attack_from, clicked_u->get_location());

                    }
                    // restore unit as before
                    u = units_.find(src);
                    u->set_movement(move_left_src);
                    u->set_standing();

                    if (choice < 0) {
                        // user hit cancel, don't start move+attack
                        return false;
                    }
                } // end planned unit map scope

                if (resources::whiteboard->is_active()) {
                    save_whiteboard_attack(attack_from, hex, choice);
                } else {
                    // store side, since u may be invalidated later
                    int side = u->side();
                    //record visible enemies adjacent to destination
                    std::set<map_location> adj_enemies = get_adj_enemies(attack_from, side);

                    // move the unit without clearing fog (to avoid interruption)
                    //TODO: clear fog and interrupt+resume move
                    if(!move_unit_along_current_route(false)) {
                        // interrupted move
                        // we assume that move_unit() did the cleaning
                        // (update shroud/fog, clear undo if needed)
                        return false;
                    }

                    //check if new enemies are now visible
                    if(get_adj_enemies(attack_from, side) != adj_enemies)
                        return false; //ambush, interrupt attack

                    attack_enemy(attack_from, hex, choice); // Fight !!
                }
                return false;
            }
        }
    }
    //otherwise we're trying to move to a hex
    else if((!browse || resources::whiteboard->is_active()) && !commands_disabled &&
            selected_hex_.valid() && selected_hex_ != hex &&
             u != units_.end() && u.valid() &&
             (u->side() == side_num_ || resources::whiteboard->is_active()) &&
             clicked_u == units_.end() &&
             !current_route_.steps.empty() &&
             current_route_.steps.front() == selected_hex_) {

        // If the whiteboard is active, it intercepts any unit movement
        if (resources::whiteboard->is_active()) {
                // Unselect the current hex, and create planned move for whiteboard
                selected_hex_ = map_location();
                gui().select_hex(map_location());
                gui().clear_attack_indicator();
                gui().set_route(NULL);
                show_partial_move_ = false;
                gui().unhighlight_reach();
                current_paths_ = pathfind::paths();
                current_route_.steps.clear();

                resources::whiteboard->save_temp_move();

        // Otherwise proceed to normal unit movement
        } else {
            //Don't move if the selected unit already has actions
            //from the whiteboard.
            if (resources::whiteboard->unit_has_actions(&*u)) {
                return false;
            }

            move_unit_along_current_route(current_team().auto_shroud_updates());
            // during the move, we may have selected another unit
            // (but without triggering a select event (command was disabled)
            // in that case reselect it now to fire the event (+ anim & sound)
            if (selected_hex_ != src) {
                select_hex(selected_hex_, browse);
            }
        }
        return false;
    } else {
        // we select a (maybe empty) hex
        // we block selection during attack+move (because motion is blocked)
        select_hex(hex, browse);
    }
    return false;
    //FIXME: clean all these "return false"
}

void mouse_handler::select_hex(const map_location& hex, const bool browse, const bool highlight, const bool fire_event) {
    selected_hex_ = hex;
    gui().select_hex(hex);
    gui().clear_attack_indicator();
    gui().set_route(NULL);
    show_partial_move_ = false;

    wb::future_map_if_active planned_unit_map; //lasts for whole method

    unit_map::iterator u = find_unit(hex);

    if (hex.valid() && u != units_.end() && u.valid() && !u->get_hidden()) {

        next_unit_ = u->get_location();

        {
            current_paths_ = pathfind::paths(map_, units_, *u, teams_,
                false, true, viewing_team(), path_turns_);
        }
        if(highlight) {
            show_attack_options(u);
            gui().highlight_reach(current_paths_);
        }
        // the highlight now comes from selection
        // and not from the mouseover on an enemy
        enemy_paths_ = false;
        gui().set_route(NULL);

        // selection have impact only if we are not observing and it's our unit
        if ((!commands_disabled || resources::whiteboard->is_active()) && u->side() == gui().viewing_side()) {
            if (!(browse || resources::whiteboard->unit_has_actions(&*u)))
            {
                sound::play_UI_sound("select-unit.wav");
                u->set_selecting();
                if(fire_event) {
                    // ensure unit map is back to normal while event is fired
                    wb::real_map srum;
                    game_events::fire("select", hex);
                    //end forced real unit map
                }
            }
        }

    } else {
        gui().unhighlight_reach();
        current_paths_ = pathfind::paths();
        current_route_.steps.clear();
        resources::whiteboard->on_deselect_hex();
    }
}

void mouse_handler::deselect_hex() {
    select_hex(map_location(), true);
}

bool mouse_handler::move_unit_along_current_route(bool check_shroud)
{
    // do not show footsteps during movement
    gui().set_route(NULL);
    gui().unhighlight_reach();

    // do not keep the hex highlighted that we started from
    selected_hex_ = map_location();
    gui().select_hex(map_location());

    bool finished_moves = move_unit_along_route(current_route_, &next_unit_, check_shroud);

    // invalid after the move
    current_paths_ = pathfind::paths();
    current_route_.steps.clear();

    return finished_moves;
}

bool mouse_handler::move_unit_along_route(pathfind::marked_route const& route, map_location* next_unit, bool check_shroud, bool* sighted_result)
{
    const std::vector<map_location> steps = route.steps;
    if(steps.empty()) {
        return false;
    }

    //If this is a leader on a keep, ask permission to the whiteboard to move it
    //since otherwise it may cause planned recruits to be erased.
    {
        unit_map::const_iterator const u = units_.find(steps.front());

        if (u != units_.end()
                && u->can_recruit()
                && u->side() == gui().viewing_side()
                && resources::game_map->is_keep(u->get_location())
                && !resources::whiteboard->allow_leader_to_move(*u))
        {
            gui2::show_transient_message(gui_->video(), "",
                    _("You cannot move your leader away from the keep with some planned recruits or recalls left."));

            if(next_unit)
                *next_unit = steps.front();
            return false;
        }
    }

    size_t moves = 0;
    try {
        moves = ::move_unit(NULL, steps, &recorder, resources::undo_stack, true, next_unit, false, check_shroud, false, sighted_result);
    } catch(end_turn_exception&) {
        cursor::set(cursor::NORMAL);
        gui().invalidate_game_status();
        throw;
    }

    cursor::set(cursor::NORMAL);
    gui().invalidate_game_status();

    if(moves == 0)
        return false;

    resources::redo_stack->clear();

    assert(moves <= steps.size());
    const map_location& dst = steps[moves-1];
    const unit_map::const_iterator u = units_.find(dst);

    //u may be equal to units_.end() in the case of e.g. a [teleport]
    if(u != units_.end()) {
        if(dst != steps.back()) {
            // the move was interrupted (or never started)
            if (u->movement_left() > 0) {
                // reselect the unit (for "press t to continue")
                select_hex(dst, false);
                // the new discovery is more important than the new movement range
                show_partial_move_ = true;
                gui().unhighlight_reach();
            }
        }
    }

    return moves == steps.size();
}

void mouse_handler::save_whiteboard_attack(const map_location& attacker_loc, const map_location& defender_loc, int weapon_choice)
{

    {
        // @todo Fix flickering/reach highlight anomaly after the weapon choice dialog is closed
        // This method should do the cleanup of highlights and selection but it doesn't work properly

        // gui().highlight_hex(map_location());

        gui().draw();
        gui().unhighlight_reach();
        gui().clear_attack_indicator();

        // remove footsteps if any - useless for whiteboard as of now
        gui().set_route(NULL);

        // do not keep the hex that we started from highlighted
        selected_hex_ = map_location();
        gui().select_hex(map_location());
        show_partial_move_ = false;

        // invalid after saving the move
        current_paths_ = pathfind::paths();
        current_route_.steps.clear();
    }

    //create planned attack for whiteboard
    resources::whiteboard->save_temp_attack(attacker_loc, defender_loc, weapon_choice);

}

int mouse_handler::fill_weapon_choices(std::vector<battle_context>& bc_vector, unit_map::iterator attacker, unit_map::iterator defender)
{
    int best = 0;
    for (unsigned int i = 0; i < attacker->attacks().size(); i++) {
        // skip weapons with attack_weight=0
        if (attacker->attacks()[i].attack_weight() > 0) {
            battle_context bc(*resources::units, attacker->get_location(), defender->get_location(), i);
            bc_vector.push_back(bc);
            if (bc.better_attack(bc_vector[best], 0.5)) {
                // as some weapons can be hidden, i is not a valid index into the resulting vector
                best = bc_vector.size() - 1;
            }
        }
    }
    return best;
}

int mouse_handler::show_attack_dialog(const map_location& attacker_loc, const map_location& defender_loc)
{

    unit_map::iterator attacker = units_.find(attacker_loc);
    unit_map::iterator defender = units_.find(defender_loc);
    if(attacker == units_.end() || defender == units_.end()) {
        ERR_NG << "One fighter is missing, can't attack";
        return -1; // abort, click will do nothing
    }

    std::vector<battle_context> bc_vector;
    const int best = fill_weapon_choices(bc_vector, attacker, defender);

    if(gui2::new_widgets) {
        gui2::tunit_attack dlg(
                  attacker
                , defender
                , bc_vector
                , best);

        dlg.show(resources::screen->video());

        if(dlg.get_retval() == gui2::twindow::OK) {
            return dlg.get_selected_weapon();
        } else {
            return -1;
        }
    }

    if (bc_vector.empty())
    {
        dialogs::units_list_preview_pane attacker_preview(&*attacker, dialogs::unit_preview_pane::SHOW_BASIC, true);
        dialogs::units_list_preview_pane defender_preview(&*defender, dialogs::unit_preview_pane::SHOW_BASIC, false);
        std::vector<gui::preview_pane*> preview_panes;
        preview_panes.push_back(&attacker_preview);
        preview_panes.push_back(&defender_preview);

        gui::show_dialog(gui(), NULL, _("Attack Enemy"),
            _("No usable weapon"), gui::CANCEL_ONLY, NULL,
            &preview_panes, "", NULL, -1, NULL, -1, -1, NULL, NULL);
        return -1;
    }


    std::vector<std::string> items;

    for (unsigned int i = 0; i < bc_vector.size(); i++) {
        const battle_context_unit_stats& att = bc_vector[i].get_attacker_stats();
        const battle_context_unit_stats& def = bc_vector[i].get_defender_stats();
        config tmp_config;
        attack_type no_weapon(tmp_config);
        const attack_type& attw = attack_type(*att.weapon);
        const attack_type& defw = attack_type(def.weapon ? *def.weapon : no_weapon);

        attw.set_specials_context(attacker->get_location(), defender->get_location(), *attacker, true);
        defw.set_specials_context(attacker->get_location(), defender->get_location(), *attacker, false);

        // if missing, add dummy special, to be sure to have
        // big enough minimum width (weapon's name can be very short)
        std::string att_weapon_special = attw.weapon_specials();
        if (att_weapon_special.empty())
            att_weapon_special += "       ";
        std::string def_weapon_special = defw.weapon_specials();
        if (def_weapon_special.empty())
            def_weapon_special += "       ";

        std::stringstream atts;
        if (static_cast<int>(i) == best) {
            atts << DEFAULT_ITEM;
        }

        std::string range = attw.range().empty() ? defw.range() : attw.range();
        if (!range.empty()) {
            range = string_table["range_" + range];
        }

        // add dummy names if missing, to keep stats aligned
        std::string attw_name = attw.name();
        if(attw_name.empty())
            attw_name = " ";
        std::string defw_name = defw.name();
        if(defw_name.empty())
            defw_name = " ";

        // color CtH in red-yellow-green
        SDL_Color att_cth_color =
                int_to_color( game_config::red_to_green(att.chance_to_hit) );
        SDL_Color def_cth_color =
                int_to_color( game_config::red_to_green(def.chance_to_hit) );

        atts << IMAGE_PREFIX << attw.icon() << COLUMN_SEPARATOR
             << font::BOLD_TEXT << attw_name  << "\n"
             << att.damage << font::weapon_numbers_sep << att.num_blows
             << "  " << att_weapon_special << "\n"
             << font::color2markup(att_cth_color) << att.chance_to_hit << "%"
             << COLUMN_SEPARATOR << font::weapon_details << utils::unicode_em_dash + " " << range << " " + utils::unicode_em_dash << COLUMN_SEPARATOR
             << font::BOLD_TEXT << defw_name  << "\n"
             << def.damage << font::weapon_numbers_sep << def.num_blows
             << "  " << def_weapon_special << "\n"
             << font::color2markup(def_cth_color) << def.chance_to_hit << "%"
             << COLUMN_SEPARATOR << IMAGE_PREFIX << defw.icon();

        items.push_back(atts.str());
    }

    attack_prediction_displayer ap_displayer(bc_vector, attacker_loc, defender_loc);
    std::vector<gui::dialog_button_info> buttons;
    buttons.push_back(gui::dialog_button_info(&ap_displayer, _("Damage Calculations")));

    int res = 0;
    {
        dialogs::units_list_preview_pane attacker_preview(&*attacker, dialogs::unit_preview_pane::SHOW_BASIC, true);
        dialogs::units_list_preview_pane defender_preview(&*defender, dialogs::unit_preview_pane::SHOW_BASIC, false);
        std::vector<gui::preview_pane*> preview_panes;
        preview_panes.push_back(&attacker_preview);
        preview_panes.push_back(&defender_preview);

        res = gui::show_dialog(gui(),NULL,_("Attack Enemy"),
                _("Choose weapon:")+std::string("\n"),
                gui::OK_CANCEL,&items,&preview_panes,"",NULL,-1,NULL,-1,-1,
                NULL,&buttons);
    }
    cursor::set(cursor::NORMAL);

    return res;
}

void mouse_handler::attack_enemy(const map_location& attacker_loc, const map_location& defender_loc, int choice)
{
    try {
        attack_enemy_(attacker_loc, defender_loc, choice);
    } catch(std::bad_alloc) {
        lg::wml_error << "Memory exhausted a unit has either a lot hitpoints or a negative amount.\n";
    }
}

void mouse_handler::attack_enemy_(const map_location& att_loc
        , const map_location& def_loc
        , int choice)
{
    //NOTE: copy the values because the const reference may change!
    //(WML events and mouse inputs during animations may modify
    // the data of the caller)
    const map_location attacker_loc = att_loc;
    const map_location defender_loc = def_loc;

    //may fire event and modify things
    apply_shroud_changes(*resources::undo_stack, side_num_);
    resources::undo_stack->clear();
    resources::redo_stack->clear();

    unit_map::iterator attacker = find_unit(attacker_loc);
    if(attacker == units_.end()
            || attacker->side() != side_num_
            || attacker->incapacitated())
        return;

    unit_map::iterator defender = find_unit(defender_loc);
    if(defender == units_.end()
            || current_team().is_enemy(defender->side()) == false
            || defender->incapacitated())
        return;

    std::vector<battle_context> bc_vector;
    fill_weapon_choices(bc_vector, attacker, defender);

    if(size_t(choice) >= bc_vector.size()) {
        return;
    }

    commands_disabled++;
    const battle_context_unit_stats &att = bc_vector[choice].get_attacker_stats();
    const battle_context_unit_stats &def = bc_vector[choice].get_defender_stats();

    attacker->set_goto(map_location());

    current_paths_ = pathfind::paths();
    // make the attacker's stats appear during the attack
    gui().display_unit_hex(attacker_loc);
    // remove highlighted hexes etc..
    gui().select_hex(map_location());
    gui().highlight_hex(map_location());
    gui().clear_attack_indicator();
    gui().unhighlight_reach();
    gui().draw();

    ///@todo change ToD to be location specific for the defender
    recorder.add_attack(attacker_loc, defender_loc, att.attack_num, def.attack_num,
        attacker->type_id(), defender->type_id(), att.level,
        def.level, resources::tod_manager->turn(), resources::tod_manager->get_time_of_day());
    rand_rng::invalidate_seed();
    if (rand_rng::has_valid_seed()) { //means SRNG is disabled
        perform_attack(attacker_loc, defender_loc, att.attack_num, def.attack_num, rand_rng::get_last_seed());
    } else {
        rand_rng::set_new_seed_callback(boost::bind(&mouse_handler::perform_attack,
            this, attacker_loc, defender_loc, att.attack_num, def.attack_num, _1));
    }
}

void mouse_handler::perform_attack(
    map_location attacker_loc, map_location defender_loc,
    int attacker_weapon, int defender_weapon, int seed)
{
    // this function gets it's arguments by value because the calling function
    // object might get deleted in the clear callback call below, invalidating
    // const ref arguments
    rand_rng::clear_new_seed_callback();
    LOG_NG << "Performing attack with seed " << seed << "\n";
    recorder.add_seed("attack", seed);
    //MP_COUNTDOWN grant time bonus for attacking
    current_team().set_action_bonus_count(1 + current_team().action_bonus_count());

    try {
        events::command_disabler disabler; // Rather than decrementing for every possible exception, use RAII
        commands_disabled--;
        attack_unit(attacker_loc, defender_loc, attacker_weapon, defender_weapon);
    } catch(end_level_exception&) {
        //if the level ends due to a unit being killed, still see if
        //either the attacker or defender should advance
        dialogs::advance_unit(attacker_loc);
        unit_map::const_iterator defu = units_.find(defender_loc);
        if (defu != units_.end()) {
            bool defender_human = teams_[defu->side() - 1].is_human();
            dialogs::advance_unit(defender_loc, !defender_human);
        }
        throw;
    }

    dialogs::advance_unit(attacker_loc);
    unit_map::const_iterator defu = units_.find(defender_loc);
    if (defu != units_.end()) {
        bool defender_human = teams_[defu->side() - 1].is_human();
        dialogs::advance_unit(defender_loc, !defender_human);
    }

    resources::controller->check_victory();
    gui().draw();
}

std::set<map_location> mouse_handler::get_adj_enemies(const map_location& loc, int side) const
{
    std::set<map_location> res;

    const team& uteam = teams_[side-1];

    map_location adj[6];
    get_adjacent_tiles(loc, adj);
    foreach (const map_location &aloc, adj) {
        unit_map::const_iterator i = find_unit(aloc);
        if (i != units_.end() && uteam.is_enemy(i->side()))
            res.insert(aloc);
    }
    return res;
}

/**
 * Causes attackable hexes to be higlighted.
 *
 * This checks the hexes that the provided unit can attack. If there is a valid
 * target there, that location is inserted into current_paths_.destinations.
 */
void mouse_handler::show_attack_options(const unit_map::const_iterator &u)
{
    // Cannot attack if no attacks are left.
    if (u->attacks_left() == 0)
          return;

    // Get the teams involved.
    const team & cur_team = current_team();
    const team & u_team = teams_[u->side()-1];

    // Check each adjacent hex.
    map_location adj[6];
    get_adjacent_tiles(u->get_location(), adj);
    foreach (const map_location &loc, adj)
    {
        // No attack option shown if no visible unit present.
        // (Visible to current team, not necessarily the unit's team.)
        if (!map_.on_board(loc)) continue;
        unit_map::const_iterator i = units_.find(loc);
        if ( i == units_.end()  ||  !i->is_visible_to_team(cur_team) )
            continue;
        const unit &target = *i;
        // Can only attack non-petrified enemies.
        if ( u_team.is_enemy(target.side())  &&  !target.incapacitated() )
            current_paths_.destinations.insert(loc);
    }
}

bool mouse_handler::unit_in_cycle(unit_map::const_iterator it)
{
    if (it == units_.end())
        return false;

    if (it->side() != side_num_ || it->user_end_turn()
        || gui().fogged(it->get_location()) || !unit_can_move(*it))
        return false;

    if (current_team().is_enemy(int(gui().viewing_team()+1)) &&
        it->invisible(it->get_location()))
        return false;

    if (it->get_hidden())
        return false;

    return true;

}

void mouse_handler::cycle_units(const bool browse, const bool reverse)
{
    if (units_.begin() == units_.end()) {
        return;
    }

    unit_map::const_iterator it = find_unit(next_unit_);
    if (it == units_.end())
        it = units_.begin();
    const unit_map::const_iterator itx = it;

    do {
        if (reverse) {
            if (it == units_.begin())
                it = units_.end();
            --it;
        } else {
            if (it == units_.end())
                it = units_.begin();
            else
                ++it;
        }
    } while (it != itx && !unit_in_cycle(it));

    if (unit_in_cycle(it)) {
        gui().scroll_to_tile(it->get_location(), game_display::WARP);
        select_hex(it->get_location(), browse);
//      mouse_update(browse);
    }
}

void mouse_handler::set_current_paths(pathfind::paths new_paths) {
    gui().unhighlight_reach();
    current_paths_ = new_paths;
    current_route_.steps.clear();
    gui().set_route(NULL);
    resources::whiteboard->erase_temp_move();
}

mouse_handler *mouse_handler::singleton_ = NULL;
}