skill_util.cpp

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/*
 * Crossfire -- cooperative multi-player graphical RPG and adventure game
 *
 * Copyright (c) 1999-2014 Mark Wedel and the Crossfire Development Team
 * Copyright (c) 1992 Frank Tore Johansen
 *
 * Crossfire is free software and comes with ABSOLUTELY NO WARRANTY. You are
 * welcome to redistribute it under certain conditions. For details, please
 * see COPYING and LICENSE.
 *
 * The authors can be reached via e-mail at <crossfire@metalforge.org>.
 */

/* define the following for skills utility debugging */
/* #define SKILL_UTIL_DEBUG */

#include "global.h"

#include <assert.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

#include "living.h"
#include "object.h"
#include "shop.h"
#include "skills.h"
#include "spells.h"
#include "sproto.h"
#include "assets.h"

static void attack_hth(object *pl, int dir, const char *string, object *skill);
static void attack_melee_weapon(object *op, int dir, const char *string, object *skill);

const char *skill_names[MAX_SKILLS];
const Face *skill_faces[MAX_SKILLS];

sstring skill_messages[MAX_SKILLS];

static int free_skill_index() {
    int i;
    for (i = 0; i < MAX_SKILLS; i++) {
        if (skill_names[i] == NULL && skill_faces[i] == NULL) {
            break;
        }
    }
    return i;
}
static void do_each_skill(archetype *at) {
    if (at->clone.type == SKILL) {
        int i = free_skill_index();
        if (i == MAX_SKILLS) {
            LOG(llevError, "init_skills: too many skills, increase MAX_SKILLS and rebuild server!");
            fatal(SEE_LAST_ERROR);
        }
        skill_names[i] = add_refcount(at->clone.skill);
        if (at->clone.face != NULL)
            skill_faces[i] = at->clone.face;
        if (at->clone.msg)
          skill_messages[i] = add_string(at->clone.msg);
    }
}

void init_skills(void) {
    int i;

    for (i = 0; i < MAX_SKILLS; i++) {
        skill_names[i] = NULL;
        skill_faces[i] = NULL;
        skill_messages[i] = NULL;
    }

    archetypes_for_each(do_each_skill);
}

int get_skill_client_code(const char *skill_name)
{
    int index;
    for (index = 0; index < MAX_SKILLS && skill_names[index] != NULL; index++)
        if (strcmp(skill_names[index], skill_name) == 0)
            return index;

    assert("invalid skill!");
    return 0;
}

static object *adjust_skill_tool(object *who, object *skill, object *skill_tool) {
    if (!skill && !skill_tool)
        return NULL;

    /* If this is a skill that can be used without a tool and no tool found, return it */
    if (skill && QUERY_FLAG(skill, FLAG_CAN_USE_SKILL) && (!skill_tool || QUERY_FLAG(skill_tool, FLAG_APPLIED) || strcmp(skill->skill, "clawing")  == 0))
        return skill;

    /* Player has a tool to use the skill.  If not applied, apply it -
     * if not successful, return skill if can be used.  If they do have the skill tool
     * but not the skill itself, give it to them.
     */
    if (skill_tool) {
        if (!QUERY_FLAG(skill_tool, FLAG_APPLIED)) {
            if (apply_special(who, skill_tool, 0)) {
                if (skill && QUERY_FLAG(skill, FLAG_CAN_USE_SKILL))
                    return skill;
                else
                    return NULL;
            }
        }
        if (!skill) {
            skill = give_skill_by_name(who, skill_tool->skill);
            link_player_skills(who);
        }
        return skill;
    }
    if (skill && QUERY_FLAG(skill, FLAG_CAN_USE_SKILL))
        return skill;
    else
        return NULL;
}

object *find_skill_by_name(object *who, const char *name) {
    object *skill = NULL, *skills[MAX_SKILLS], *skill_tools[MAX_SKILLS];
    const char *skill_names[MAX_SKILLS];
    char *ourname=NULL;
    int num_names, highest_level_skill=0, i;

    if (!name)
        return NULL;

    /* Simple case - no commas in past in name, so don't need to tokenize */
    if (!strchr(name, ',')) {
        skill_names[0] = name;
        skill_tools[0] = NULL;
        skills[0] = NULL;
        num_names = 1;
    } else {
        /* strtok_r is destructive, so we need our own copy */
        char *lasts;
        ourname = strdup(name);

        if ((skill_names[0] = strtok_r(ourname, ",", &lasts)) == NULL) {
            /* This should really never happen */
            LOG(llevError, "find_skill_by_name: strtok_r returned null, but strchr did not?\n");
            free(ourname);
            return NULL;
        } else {
            skill_tools[0] = NULL;
            skills[0] = NULL;
            /* we already have the first name from the strtok_r above */
            num_names=1;
            while ((skill_names[num_names] = strtok_r(NULL, ",", &lasts)) != NULL) {
                /* Clean out any leading spacing.  typical string would be
                 * skill1, skill2, skill3, ...
                 */
                while (isspace(*skill_names[num_names]))
                    skill_names[num_names]++;
                skills[num_names] = NULL;
                skill_tools[num_names] = NULL;
                num_names++;
            }
        }
        /* While we don't use ourname below this point, the skill_names[] points into
         * it, so we can't free it yet.
         */
    }

    FOR_INV_PREPARE(who, tmp) {
       /* We make sure the length of the string in the object is greater
        * in length than the passed string. Eg, if we have a skill called
        * 'hi', we don't want to match if the user passed 'high'
        */
        if (tmp->type == SKILL || (tmp->type == SKILL_TOOL && !QUERY_FLAG(tmp, FLAG_UNPAID))) {
            for (i = 0; i<num_names; i++) {
                if (!strncasecmp(skill_names[i], tmp->skill, strlen(skill_names[i])) &&
                    strlen(tmp->skill) >= strlen(skill_names[i])) {
                    if (tmp->type == SKILL) {
                        skills[i] = tmp;
                        if (!skill || tmp->level > skill->level) {
                            skill = tmp;
                            highest_level_skill=i;
                        }
                    }
                    else {
                        /* Skill tools don't have levels, so we basically find the
                         * 'best' skill tool for this skill.
                         */
                        if (QUERY_FLAG(tmp, FLAG_APPLIED) || !skill_tools[i] ||
                            !QUERY_FLAG(skill_tools[i], FLAG_APPLIED)) {
                                skill_tools[i] = tmp;
                            }
                    }
                    /* Got a matching name - no reason to look through rest of names */
                    break;
                }
            }
        }
    } FOR_INV_FINISH();
    free(ourname);
    return adjust_skill_tool(who, skills[highest_level_skill], skill_tools[highest_level_skill]);
}

object *find_skill_by_number(object *who, int skillno) {
    object *skill = NULL, *skill_tool = NULL;

    if (skillno <= 0 || skillno > MAX_SKILLS) {
        return NULL;
    }

    FOR_INV_PREPARE(who, tmp) {
        if (tmp->type == SKILL && tmp->subtype == skillno)
            skill = tmp;

        /* Try to find appropriate skilltool.  If the player has one already
         * applied, we try to keep using that one.
         */
        else if (tmp->type == SKILL_TOOL && tmp->subtype == skillno) {
            if (QUERY_FLAG(tmp, FLAG_APPLIED))
                skill_tool = tmp;
            else if (!skill_tool || !QUERY_FLAG(skill_tool, FLAG_APPLIED))
                skill_tool = tmp;
        }
    } FOR_INV_FINISH();

    return adjust_skill_tool(who, skill, skill_tool);
}

int change_skill(object *who, object *new_skill, int flag) {
    rangetype old_range;

    if (who->type != PLAYER)
        return 0;

    old_range = who->contr->shoottype;

    /* The readied skill can be a skill tool, so check on actual skill instead of object. */
    if (new_skill && who->chosen_skill && who->chosen_skill->skill == new_skill->skill) {
        /* optimization for changing skill to current skill */
        if (!(flag&0x1))
            who->contr->shoottype = range_skill;
        return 1;
    }

    if (who->chosen_skill)
        apply_special(who, who->chosen_skill, AP_UNAPPLY|(flag&AP_NOPRINT));

    /* Only goal in this case was to unapply a skill */
    if (!new_skill)
        return 0;

    if (apply_special(who, new_skill, AP_APPLY|(flag&AP_NOPRINT))) {
        return 0;
    }
    if (flag&0x1)
        who->contr->shoottype = old_range;

    return 1;
}

void clear_skill(object *who) {
    who->chosen_skill = NULL;
    CLEAR_FLAG(who, FLAG_READY_SKILL);
    if (who->type == PLAYER) {
        who->contr->ranges[range_skill] = NULL;
        if (who->contr->shoottype == range_skill)
            who->contr->shoottype = range_none;
    }
}

struct do_skill_cb_data {
    object *op;
    object *part;
    object *skill;
    int dir;
    const char *string;
};

bool do_skill_cb(player *pl, void *data) {
    struct do_skill_cb_data *args = (struct do_skill_cb_data *)data;
    do_skill(args->op, args->part, args->skill, args->dir, args->string);
    return true;
}

int do_skill(object *op, object *part, object *skill, int dir, const char *string) {
    int success = 0, exp = 0;

    if (!skill)
        return 0;

    /* The code below presumes that the skill points to the object that
     * holds the exp, level, etc of the skill.  So if this is a player
     * go and try to find the actual real skill pointer, and if the
     * the player doesn't have a bucket for that, create one.
     */
    if (skill->type != SKILL && op->type == PLAYER) {
        object *tmp;

        tmp = object_find_by_type_and_skill(op, SKILL, skill->skill);
        if (!tmp) {
            tmp = give_skill_by_name(op, skill->skill);
            if (!tmp) {
                LOG(llevError, "do_skill: asked for skill %s but couldn't find matching SKILL archetype.\n", skill->skill);
                return 0;
            }
        }
        skill = tmp;
    }

    if (skill->anim_suffix)
        apply_anim_suffix(op, skill->anim_suffix);

    switch (skill->subtype) {
    case SK_LEVITATION:
        /* Not 100% sure if this will work with new movement code -
         * the levitation skill has move_type for flying, so when
         * equipped, that should transfer to player, when not,
         * shouldn't.
         */
        if (QUERY_FLAG(skill, FLAG_APPLIED)) {
            CLEAR_FLAG(skill, FLAG_APPLIED);
            draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_SUCCESS,
                          "You come to earth.");
        } else {
            SET_FLAG(skill, FLAG_APPLIED);
            draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_SUCCESS,
                          "You rise into the air!.");
        }
        fix_object(op);
        success = 1;
        break;

    case SK_STEALING:
        exp = success = steal(op, dir, skill);
        break;

    case SK_LOCKPICKING:
        exp = success = pick_lock(op, dir, skill);
        break;

    case SK_HIDING:
        exp = success = hide(op, skill);
        break;

    case SK_JUMPING:
        success = jump(op, dir, skill);
        break;

    case SK_INSCRIPTION:
        exp = success = write_on_item(op, string, skill);
        break;

    case SK_MEDITATION:
        meditate(op, skill);
        success = 1;
        break;
        /* note that the following 'attack' skills gain exp through hit_player() */

    case SK_KARATE:
        attack_hth(op, dir, "karate-chopped", skill);
        break;

    case SK_PUNCHING:
        attack_hth(op, dir, "punched", skill);
        break;

    case SK_FLAME_TOUCH:
        attack_hth(op, dir, "flamed", skill);
        break;

    case SK_CLAWING:
        attack_hth(op, dir, "clawed", skill);
        break;

    case SK_WRAITH_FEED:
        attack_hth(op, dir, "fed upon", skill);
        break;

    case SK_ONE_HANDED_WEAPON:
    case SK_TWO_HANDED_WEAPON:
        (void)attack_melee_weapon(op, dir,  NULL, skill);
        break;

    case SK_FIND_TRAPS:
        exp = success = find_traps(op, skill);
        break;

    case SK_SINGING:
        exp = success = singing(op, dir, skill);
        break;

    case SK_ORATORY:
        exp = success = use_oratory(op, dir, skill);
        break;

    case SK_SMITHERY:
    case SK_BOWYER:
    case SK_JEWELER:
    case SK_ALCHEMY:
    case SK_THAUMATURGY:
    case SK_LITERACY:
    case SK_WOODSMAN:
        if (use_alchemy(op) == 0)
            exp = success = skill_ident(op, skill);
        break;

    case SK_DET_MAGIC:
    case SK_DET_CURSE:
        exp = success = skill_ident(op, skill);
        break;

    case SK_DISARM_TRAPS:
        exp = success = remove_trap(op, skill);
        break;

    case SK_THROWING:
        success = skill_throw(op, part, dir, skill);
        break;

    case SK_SET_TRAP:
        draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                      "This skill is not currently implemented.");
        break;

    case SK_USE_MAGIC_ITEM:
    case SK_MISSILE_WEAPON:
        draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                      "There is no special attack for this skill.");
        break;

    case SK_PRAYING:
        if (op->contr) {
            player_start_repeat(op->contr, "praying", do_skill_cb);
            op->contr->repeat_func_data = calloc(1, sizeof(struct do_skill_cb_data));
            struct do_skill_cb_data *data = (struct do_skill_cb_data *)op->contr->repeat_func_data;
            *data = {op, part, skill, dir, string};
        }
        success = pray(op, skill);
        break;

    case SK_BARGAINING:
        success = shop_describe(op);
        break;

    case SK_SORCERY:
    case SK_EVOCATION:
    case SK_PYROMANCY:
    case SK_SUMMONING:
    case SK_CLIMBING:
    case SK_EARTH_MAGIC:
    case SK_AIR_MAGIC:
    case SK_FIRE_MAGIC:
    case SK_WATER_MAGIC:
        draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                      "This skill is already in effect.");
        break;

    case SK_HARVESTING:
        if (op->contr) {
            player_start_repeat(op->contr, skill->name, do_skill_cb);
            op->contr->repeat_func_data = calloc(1, sizeof(struct do_skill_cb_data));
            struct do_skill_cb_data *data = (struct do_skill_cb_data *)op->contr->repeat_func_data;
            *data = {op, part, skill, dir, string};
        }
        do_harvest(op, dir, skill);
        success = 0;
        break;

    default: {
            char name[MAX_BUF];

            query_name(op, name, MAX_BUF);
            LOG(llevDebug, "%s attempted to use unknown skill: %d\n", name, op->chosen_skill->stats.sp);
            break;
        }
    }

    /* For players we now update the speed_left from using the skill.
     * Monsters have no skill use time because of the random nature in
     * which use_monster_skill is called already simulates this.
     * If certain skills should take more/less time, that should be
     * in the code for the skill itself.
     */

    if (op->type == PLAYER)
        op->speed_left -= 1.0;

    /* this is a good place to add experience for successful use of skills.
     * Note that add_exp() will figure out player/monster experience
     * gain problems.
     */

    if (success && exp)
        change_exp(op, exp, skill->skill, SK_SUBTRACT_SKILL_EXP);

    return success;
}

int64_t calc_skill_exp(const object *who, const object *op, const object *skill) {
    int64_t op_exp;
    int op_lvl;
    float base, value, lvl_mult;

    if (!skill)
        skill = who;

    /* Oct 95 - where we have an object, I expanded our treatment
     * to 3 cases:
     * non-living magic obj, runes and everything else.
     *
     * If an object is not alive and magical we set the base exp higher to
     * help out exp awards for skill_ident skills. Also, if
     * an item is type RUNE, we give out exp based on stats.Cha
     * and level (this was the old system) -b.t.
     */

    if (!op) {  /* no item/creature */
        op_lvl = MAX(who->map->difficulty, 1);
        op_exp = 0;
    } else if (op->type == RUNE || op->type == TRAP) { /* all traps. If stats.Cha > 1 we use that
     * for the amount of experience */
        op_exp = op->stats.Cha > 1 ? op->stats.Cha : op->stats.exp;
        op_lvl = op->level;
    } else {   /* all other items/living creatures */
        op_exp = op->stats.exp;
        op_lvl = op->level;
        if (!QUERY_FLAG(op, FLAG_ALIVE)) { /* for ident/make items */
            op_lvl += 5*abs(op->magic);
        }
    }

    if (op_lvl < 1)
        op_lvl = 1;

    if (who->type != PLAYER) {            /* for monsters only */
        return ((int64_t)(op_exp*0.1)+1);  /* we add one to insure positive value is returned */
    }

    /* for players */
    base = op_exp;
    /* if skill really is a skill, then we can look at the skill archetype for
     * base reward value (exp) and level multiplier factor.
     */
    if (skill->type == SKILL) {
        base += skill->arch->clone.stats.exp;
        if (settings.simple_exp) {
            if (skill->arch->clone.level)
                lvl_mult = (float)skill->arch->clone.level/100.0;
            else
                lvl_mult = 1.0; /* no adjustment */
        } else {
            if (skill->level)
                lvl_mult = ((float)skill->arch->clone.level*(float)op_lvl)/((float)skill->level*100.0);
            else
                lvl_mult = 1.0;
        }
    } else {
        /* Don't divide by zero here! */
        lvl_mult = (float)op_lvl/(float)(skill->level ? skill->level : 1);
    }

    /* assemble the exp total, and return value */

    value = base*lvl_mult;
    if (value < 1)
        value = 1; /* Always give at least 1 exp point */

#ifdef SKILL_UTIL_DEBUG
    LOG(llevDebug, "calc_skill_exp(): who: %s(lvl:%d)  op:%s(lvl:%d)\n", who->name, skill->level, op ? op->name : "", op_lvl);
#endif
    return ((int64_t)value);
}

int learn_skill(object *pl, object *scroll) {
    object *tmp;

    if (!scroll->skill) {
        LOG(llevError, "skill scroll %s does not have skill pointer set.\n", scroll->name);
        return 2;
    }

    /* can't use find_skill_by_name because we want skills the player knows
     * but can't use natively.
     */

    tmp = NULL;
    FOR_INV_PREPARE(pl, inv)
        if (inv->type == SKILL && !strncasecmp(scroll->skill, inv->skill, strlen(scroll->skill))) {
            tmp = inv;
            break;
        }
    FOR_INV_FINISH();

    /* player already knows it */
    if (tmp && QUERY_FLAG(tmp, FLAG_CAN_USE_SKILL))
        return 0;

    /* now a random change to learn, based on player Int.
     * give bonus based on level - otherwise stupid characters
     * might never be able to learn anything.
     */
    if (random_roll(0, 99, pl, PREFER_LOW) > (get_learn_spell(pl->stats.Int)+(pl->level/5)))
        return 2; /* failure :< */

    if (!tmp)
        tmp = give_skill_by_name(pl, scroll->skill);

    if (!tmp) {
        LOG(llevError, "skill scroll %s does not have valid skill name (%s).\n", scroll->name, scroll->skill);
        return 2;
    }

    SET_FLAG(tmp, FLAG_CAN_USE_SKILL);
    link_player_skills(pl);
    return 1;
}

static int clipped_percent(int64_t a, int64_t b) {
    int rv;

    if (b <= 0)
        return 0;

    rv = (int)((100.0f*((float)a)/((float)b))+0.5f);

    if (rv < 0)
        return 0;
    else if (rv > 100)
        return 100;

    return rv;
}


static int digits_in_long(int64_t num)
{
    return num == 0 ? 1 : floor( log10( labs(num) ) ) + 1;
}

void show_skills(object *op, const char *parms) {
    const char *cp;
    int i, num_skills_found = 0;
    /* Need to have a pointer and use strdup for qsort to work properly */
    char skills[MAX_SKILLS][MAX_BUF];
    const char *search = parms;
    bool long_format = false;

    if ( parms && strncmp(parms,"-l",2) == 0 ) {
       long_format = true;
       search += 2;
       while ( *search && *search != ' ' ) ++search; /* move past other parameters */
       while ( *search == ' ' ) ++search;
    }
    FOR_INV_PREPARE(op, tmp) {
        if (tmp->type == SKILL) {
            if (search && strstr(tmp->name, search) == NULL)
                continue;

            if (settings.permanent_exp_ratio) {
                if ( long_format ) {
                    int perm_level = exp_level(tmp->total_exp * settings.permanent_exp_ratio / 100);
                    snprintf(skills[num_skills_found++], MAX_BUF, "[fixed]%-20slvl:%3d (xp:%" FMT64 "/%" FMT64 ")%-*sperm lvl:%3d (xp:%" FMT64 "/%" FMT64 ") ",
                             tmp->name, tmp->level,
                             tmp->stats.exp,
                             level_exp(tmp->level+1, op->expmul),
                             1+2*digits_in_long(op->stats.exp)-digits_in_long(tmp->stats.exp)-digits_in_long(level_exp(tmp->level+1, op->expmul)),
                             "",
                             perm_level,
                             tmp->total_exp * settings.permanent_exp_ratio / 100,
                             level_exp(perm_level+1, op->expmul));
                } else {
                    snprintf(skills[num_skills_found++], MAX_BUF, "[fixed]%-20slvl:%3d (xp:%" FMT64 "/%" FMT64 "/%d%%)",
                             tmp->name, tmp->level,
                             tmp->stats.exp,
                             level_exp(tmp->level+1, op->expmul),
                             clipped_percent(PERM_EXP(tmp->total_exp), tmp->stats.exp));
                }
            } else {
                snprintf(skills[num_skills_found++], MAX_BUF, "[fixed]%-20slvl:%3d (xp:%" FMT64 "/%" FMT64 ")",
                         tmp->name, tmp->level,
                         tmp->stats.exp,
                         level_exp(tmp->level+1, op->expmul));
            }
            /* I don't know why some characters get a bunch of skills, but
             * it sometimes happens (maybe a leftover from buggier earlier code
             * and those character are still about).  In any case, lets handle
             * it so it doesn't crash the server - otherwise, one character may
             * crash the server numerous times.
             */
            if (num_skills_found >= MAX_SKILLS) {
                draw_ext_info(NDI_RED, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                              "Your character has too many skills.\n"
                              "Something isn't right - contact the server admin");
                break;
            }
        }
    } FOR_INV_FINISH();

    if ( search && *search ) {
        draw_ext_info_format(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_LIST,
                             "Player skills%s: (matching '%s')", long_format ? " (long format)":"",search);
    } else {
        draw_ext_info_format(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_LIST,
                             "Player skills%s:", long_format ? " (long format)":"");
    }

    if (num_skills_found > 1)
        qsort(skills, num_skills_found, MAX_BUF, (int (*)(const void *, const void *))strcmp);

    for (i = 0; i < num_skills_found; i++) {
        draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_LIST,
                      skills[i]);
    }

    cp = determine_god(op);
    if (strcmp(cp, "none") == 0)
        cp = NULL;

    draw_ext_info_format(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_LIST,
                         "You can handle %d weapon improvements.\n"
                         "You worship %s.\n"
                         "Your equipped item power is %d out of %d\n",
                         op->level/5+5,
                         cp ? cp : "no god at current time",
                         op->contr->item_power, op->level);
}

int use_skill(object *op, const char *string) {
    object *skop;
    size_t len;

    if (!string)
        return 0;

    skop = NULL;
    FOR_INV_PREPARE(op, tmp) {
        if (tmp->type == SKILL
        && QUERY_FLAG(tmp, FLAG_CAN_USE_SKILL)
        && !strncasecmp(string, tmp->skill, MIN(strlen(string), strlen(tmp->skill)))) {
            skop = tmp;
            break;
        } else if (tmp->type == SKILL_TOOL
        && !QUERY_FLAG(tmp, FLAG_UNPAID) /* Holy symbols could be used unpaid w/o this */
        && !strncasecmp(string, tmp->skill, MIN(strlen(string), strlen(tmp->skill)))) {
            skop = tmp;
            break;
        }
    } FOR_INV_FINISH();
    if (!skop) {
        draw_ext_info_format(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_MISSING,
                             "Unable to find skill %s",
                             string);
        return 0;
    }

    len = strlen(skop->skill);

    /* All this logic goes and skips over the skill name to find any
     * options given to the skill.  Its pretty simple - if there
     * are extra parameters (as determined by string length), we
     * want to skip over any leading spaces.
     */
    if (len >= strlen(string)) {
        string = NULL;
    } else {
        string += len;
        while (*string == 0x20)
            string++;
        if (strlen(string) == 0)
            string = NULL;
    }

#ifdef SKILL_UTIL_DEBUG
    LOG(llevDebug, "use_skill() got skill: %s\n", sknum > -1 ? skills[sknum].name : "none");
#endif

    /* Change to the new skill, then execute it. */
    if (do_skill(op, op, skop, op->facing, string))
        return 1;

    return 0;
}

static object *find_best_player_hth_skill(object *op) {
    object *best_skill = NULL;
    int last_skill;

    if (op->contr->unarmed_skill) {
        /* command_unarmed_skill() already does these checks, and right
         * now I do not think there is any way to lose unarmed skills.
         * But maybe in the future there will be (polymorph?) so handle
         * it appropriately.  MSW 2009-07-03
         *
         * Note that the error messages should only print out once when
         * the initial failure to switch skills happens, so the player
         * should not get spammed with tons of messages unless they have
         * no valid unarmed skill
         */

        best_skill = find_skill_by_name(op, op->contr->unarmed_skill);

        if (!best_skill) {
            draw_ext_info_format(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_MISSING,
                                 "Unable to find skill %s - using default unarmed skill",
                                 op->contr->unarmed_skill);
        } else {
            size_t i;

            for (i = 0; i < sizeof(unarmed_skills); i++)
                if (best_skill->subtype == unarmed_skills[i])
                    break;
            if (i < sizeof(unarmed_skills))
                return(best_skill);
        }
        /* If for some reason the unarmed_skill is not valid, we fall
         * through the processing below.
         */
    }


    /* Dragons are a special case - gros 25th July 2006 */
    /* Perhaps this special case should be removed and unarmed_skill
     * set to clawing for dragon characters?  MSW 2009-07-03
     */
    if (is_dragon_pl(op)) {
        object *tmp;

        tmp = find_skill_by_number(op, SK_CLAWING);
        if (tmp) /* I suppose it should always be true - but maybe there's
                  * draconic toothache ? :) */
            return tmp;
    }

    last_skill = sizeof(unarmed_skills);
    FOR_INV_PREPARE(op, tmp) {
        if (tmp->type == SKILL) {
            int i;

            /* The order in the array is preferred order.  So basically,
             * we just cut down the number to search - eg, if we find a skill
             * early on in flame touch, then we only need to look into the unarmed_array
             * to the entry before flame touch - don't care about the entries afterward,
             * because they are inferior skills.
             * if we end up finding the best skill (i==0) might as well return
             * right away - can't get any better than that.
             */
            for (i = 0; i < last_skill; i++) {
                if (tmp->subtype == unarmed_skills[i] && QUERY_FLAG(tmp, FLAG_CAN_USE_SKILL)) {
                    best_skill = tmp;
                    last_skill = i;
                    if (i == 0)
                        return best_skill;
                }
            }
        }
    } FOR_INV_FINISH();
    return best_skill;
}

static void do_skill_attack(object *tmp, object *op, const char *string, object *skill) {
    int success;

    /* For Players only: if there is no ready weapon, and no "attack" skill
     * is readied either then try to find a skill for the player to use.
     * it is presumed that if skill is set, it is a valid attack skill (eg,
     * the caller should have set it appropriately).  We still want to pass
     * through that code if skill is set to change to the skill.
     */
    if (op->type == PLAYER) {
        if (!QUERY_FLAG(op, FLAG_READY_WEAPON)) {
            size_t i;

            if (!skill) {
                /* See if the players chosen skill is a combat skill, and use
                 * it if appropriate.
                 */
                if (op->chosen_skill) {
                    /* the list is 0-terminated, and talismans, which can be in chosen_skill,
                     * have a subtype of 0, therefore don't check the 0 */
                    for (i = 0; unarmed_skills[i] != 0; i++)
                        if (op->chosen_skill->subtype == unarmed_skills[i]) {
                            skill = op->chosen_skill;
                            break;
                        }
                }
                /* If we didn't find a skill above, look harder for a good skill */
                if (!skill) {
                    skill = find_best_player_hth_skill(op);

                    if (!skill) {
                        draw_ext_info(NDI_BLACK, 0, op,
                                      MSG_TYPE_SKILL, MSG_TYPE_SKILL_MISSING,
                                      "You have no unarmed combat skills!");
                        return;
                    }
                }
            }
            if (skill != op->chosen_skill) {
                /* now try to ready the new skill */
                if (!change_skill(op, skill, 1)) { /* oh oh, trouble! */
                    draw_ext_info_format(NDI_UNIQUE, 0, tmp,
                                         MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                                         "Couldn't change to skill %s",
                                         skill->name);
                    return;
                }
            }
        } else {
            /* Seen some crashes below where current_weapon is not set,
             * even though the flag says it is.  So if current weapon isn't set,
             * do some work in trying to find the object to use.
             */
            if (!op->current_weapon) {
                object *tmp;

                LOG(llevError, "Player %s does not have current weapon set but flag_ready_weapon is set\n", op->name);
                tmp = object_find_by_type_applied(op, WEAPON);
                if (!tmp) {
                    LOG(llevError, "Could not find applied weapon on %s\n", op->name);
                    op->current_weapon = NULL;
                    return;
                } else {
                    char weapon[MAX_BUF];

                    query_name(tmp, weapon, MAX_BUF);
                    op->current_weapon = tmp;
                }
            }

            /* Has ready weapon - make sure chosen_skill is set up properly */
            if (!op->chosen_skill || op->current_weapon->skill != op->chosen_skill->skill) {
                object *found_skill = find_skill_by_name(op, op->current_weapon->skill);
                // found_skill can be NULL -- TOCTTOU when item has mutated, e.g. dipping a bottle in a fountain
                change_skill(op, found_skill, 1);
            }
        }
    }

    /* lose invisibility/hiding status for running attacks */

    if (op->type == PLAYER && op->contr->tmp_invis) {
        op->contr->tmp_invis = 0;
        op->invisible = 0;
        op->hide = 0;
        object_update(op, UP_OBJ_FACE);
    }

    success = attack_ob(tmp, op);

    if (tmp && !QUERY_FLAG(tmp, FLAG_FREED)) {
        char op_name[MAX_BUF];
        if (!success) { // In case of miss, attack_ob didn't print anything
            query_name(tmp, op_name, MAX_BUF);
            draw_ext_info_format(NDI_UNIQUE, 0, op,
                                 MSG_TYPE_ATTACK, MSG_TYPE_ATTACK_MISS,
                                 "You miss %s!",
                                 op_name);
        } else if (string != NULL) {   // If string is NULL, message was already displayed
            if (op->type == PLAYER) {
                query_name(tmp, op_name, MAX_BUF);
                draw_ext_info_format(NDI_UNIQUE, 0, op,
                                     MSG_TYPE_ATTACK, MSG_TYPE_ATTACK_DID_HIT,
                                     "You %s %s!",
                                     string, op_name);
            } else if (tmp->type == PLAYER) {
                query_name(op, op_name, MAX_BUF);
                draw_ext_info_format(NDI_UNIQUE, 0, tmp,
                                     MSG_TYPE_VICTIM, MSG_TYPE_VICTIM_WAS_HIT,
                                     "%s %s you!",
                                     op_name, string);
            }
        }
    }
}

void skill_attack(object *tmp, object *pl, int dir, const char *string, object *skill) {
    int16_t tx, ty;
    mapstruct *m;
    int mflags;

    if (!dir)
        dir = pl->facing;
    tx = freearr_x[dir];
    ty = freearr_y[dir];

    /* If we don't yet have an opponent, find if one exists, and attack.
     * Legal opponents are the same as outlined in move_player_attack()
     */

    if (tmp == NULL) {
        m = pl->map;
        tx = pl->x+freearr_x[dir];
        ty = pl->y+freearr_y[dir];

        mflags = get_map_flags(m, &m, tx, ty, &tx, &ty);
        if (mflags&P_OUT_OF_MAP)
            return;

        /* space must be blocked for there to be anything interesting to do */
        if (!(mflags&P_IS_ALIVE)
        && !OB_TYPE_MOVE_BLOCK(pl, GET_MAP_MOVE_BLOCK(m, tx, ty))) {
            return;
        }

        FOR_MAP_PREPARE(m, tx, ty, tmp2)
            if ((QUERY_FLAG(tmp2, FLAG_ALIVE) && tmp2->stats.hp >= 0)
            || QUERY_FLAG(tmp2, FLAG_CAN_ROLL)
            || tmp2->type == LOCKED_DOOR) {
                /* Don't attack party members */
                if ((pl->type == PLAYER && tmp2->type == PLAYER)
                && (pl->contr->party != NULL && pl->contr->party == tmp2->contr->party))
                    return;
                tmp = tmp2;
                break;
            }
        FOR_MAP_FINISH();
    }
    if (!tmp) {
        if (pl->type == PLAYER)
            draw_ext_info(NDI_UNIQUE, 0, pl, MSG_TYPE_SKILL, MSG_TYPE_SKILL_FAILURE,
                          "There is nothing to attack!");
        return;
    }

    do_skill_attack(tmp, pl, string, skill);
}

static void attack_hth(object *pl, int dir, const char *string, object *skill) {
    object *weapon;

    if (QUERY_FLAG(pl, FLAG_READY_WEAPON)) {
        weapon = object_find_by_type_applied(pl, WEAPON);
        if (weapon != NULL) {
            if (apply_special(pl, weapon, AP_UNAPPLY|AP_NOPRINT)) {
                char weaponname[MAX_BUF];

                query_name(weapon, weaponname, MAX_BUF);
                draw_ext_info_format(NDI_UNIQUE, 0, pl,
                                     MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                                     "You are unable to unwield %s in order to attack with %s.",
                                     weaponname, skill->name);
                return;
            } else {
                draw_ext_info(NDI_UNIQUE, 0, pl, MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                              "You unwield your weapon in order to attack.");
            }
        }
    }
    skill_attack(NULL, pl, dir, string, skill);
}

static void attack_melee_weapon(object *op, int dir, const char *string, object *skill) {
    if (!QUERY_FLAG(op, FLAG_READY_WEAPON)) {
        if (op->type == PLAYER)
            draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SKILL, MSG_TYPE_SKILL_ERROR,
                          "You have no ready weapon to attack with!");
        return;
    }
    skill_attack(NULL, op, dir, string, skill);
}