shop.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>.
 */
 
#include "global.h"
 
#include <assert.h>
#include <cmath>
#include <stdlib.h>
#include <string.h>
 
#include "shop.h"
#include "sproto.h"
 
#define SPECIALISATION_EFFECT 0.5
 
#define DISAPPROVAL_RATIO 0.2
 
#define NEUTRAL_RATIO 0.8
 
#define MAX_BUY_REDUCTION   0.1f
 
#define MAX_SELL_EXTRA      0.1f
 
static uint64_t pay_from_container(object *pl, object *pouch, uint64_t to_pay);
static uint64_t value_limit(uint64_t val, int quantity, const object *who, int isshop);
static double shop_specialisation_ratio(const object *item, const mapstruct *map);
static double shop_greed(const mapstruct *map);
 
#define NUM_COINS 5     
#define LARGEST_COIN_GIVEN 2 
static const char *const coins[] = {
    "ambercoin",
    "jadecoin",
    "platinacoin",
    "goldcoin",
    "silvercoin",
    NULL
};
 
uint64_t price_approx(const object *tmp, object *who) {
    uint64_t val = price_base(tmp);
 
    /* If we are approximating, then the value returned should
     * be allowed to be wrong however merely using a random number
     * each time will not be sufficient, as then multiple examinations
     * would give different answers, so we'll use the count instead.
     * By taking the sine of the count, a value between -1 and 1 is
     * generated, we then divide by the square root of the bargaining
     * skill and the appropriate identification skills, so that higher
     * level players get better estimates. (We need a +1 there to
     * prevent dividing by zero.)
     */
    const typedata *tmptype = get_typedata(tmp->type);
    int lev_identify = 0;
 
    if (tmptype) {
        int idskill1 = tmptype->identifyskill;
        if (idskill1) {
            int idskill2 = tmptype->identifyskill2;
            if (find_skill_by_number(who, idskill1)) {
                lev_identify = find_skill_by_number(who, idskill1)->level;
            }
            if (idskill2 && find_skill_by_number(who, idskill2)) {
                lev_identify += find_skill_by_number(who, idskill2)->level;
            }
        }
    } else {
        LOG(llevError, "Query_cost: item %s hasn't got a valid type\n", tmp->name);
    }
    val += val * (sin(tmp->count) / sqrt(lev_identify * 3 + 1.0));
 
    return val;
}
 
static float shop_cha_modifier(int charisma) {
    return tanh((charisma+15.0)/20);
}
 
float shop_efficiency(const object *player) {
    return shop_greed(player->map)
         * shop_approval(player->map, player)
         * shop_cha_modifier(player->stats.Cha);
}
 
uint64_t shop_price_buy(const object *tmp, object *who) {
    assert(who != NULL && who->type == PLAYER);
    // price tags override any buy price
    if (object_value_set(tmp, "price")) {
        const char *price = object_get_value(tmp, "price");
        return NROF(tmp)*strtol(price, NULL, 10);
    }
    const uint64_t val = price_base(tmp);
    const char *key = object_get_value(tmp, "price_adjustment_buy");
    float adj = 1;
    if (key != NULL) {
        adj = atof(key);
    }
    float E = shop_efficiency(who);
    const float adj_val = val * adj / E;
    if (getenv("CF_DEBUG_SHOP")) {
        LOG(llevDebug, "price_buy %s %lu*adj(%.2f)/E(%.2f) = %.2f\n",
                tmp->arch->name, val, adj, E, adj_val);
    }
    if (std::isfinite(adj_val)) {
        return adj_val;
    } else {
        return UINT64_MAX;
    }
}
 
uint64_t shop_price_sell(const object *tmp, object *who) {
    assert(who != NULL && who->type == PLAYER);
    const uint64_t val = price_base(tmp);
    const char *key = object_get_value(tmp, "price_adjustment_sell");
    float adj = 1;
    if (key != NULL) {
        adj = atof(key);
    }
    float spec = shop_specialisation_ratio(tmp, who->map);
    float E = shop_efficiency(who);
    const uint64_t adj_val = val * adj * spec * E;
 
    /* Limit amount of money you can get for really great items. */
    int number = NROF(tmp);
    uint64_t limval = value_limit(adj_val, number, who, 1);
 
    if (getenv("CF_DEBUG_SHOP")) {
        LOG(llevDebug, "price_sell %s %lu*adj(%.2f)*s(%.2f)*E(%.2f) = %lu limited to %lu\n",
                tmp->arch->name, val, adj, spec, E, adj_val, limval);
    }
    return limval;
}
 
static archetype *find_next_coin(uint64_t c, int *cointype) {
    archetype *coin;
 
    do {
        if (coins[*cointype] == NULL)
            return NULL;
        coin = find_archetype(coins[*cointype]);
        if (coin == NULL)
            return NULL;
        *cointype += 1;
    } while (coin->clone.value > (int64_t) c);
 
    return coin;
}
 
char* cost_string_from_value(uint64_t cost, int largest_coin) {
    archetype *coin, *next_coin;
    uint32_t num;
    int cointype = largest_coin;
 
    if (cointype < 0)
        cointype = 0;
    else if (cointype >= NUM_COINS)
        cointype = NUM_COINS - 1;
 
    StringBuffer* buf = stringbuffer_new();
    if (cost == UINT64_MAX) {
        stringbuffer_append_string(buf, "an unimaginable sum of money");
        goto done;
    }
 
    coin = find_next_coin(cost, &cointype);
    if (coin == NULL) {
        stringbuffer_append_string(buf, "nothing");
        goto done;
    }
 
    num = cost/coin->clone.value;
    /* so long as nrof is 32 bit, this is true.
     * If it takes more coins than a person can possibly carry, this
     * is basically true.
     */
    if ((cost/coin->clone.value) > UINT32_MAX) {
        stringbuffer_append_string(buf, "an unimaginable sum of money");
        goto done;
    }
 
    cost -= (uint64_t)num*(uint64_t)coin->clone.value;
    if (num == 1)
        stringbuffer_append_printf(buf, "1 %s", coin->clone.name);
    else
        stringbuffer_append_printf(buf, "%u %ss", num, coin->clone.name);
 
    next_coin = find_next_coin(cost, &cointype);
    if (next_coin == NULL)
        goto done;
 
    do {
        coin = next_coin;
        num = cost/coin->clone.value;
        cost -= (uint64_t)num*(uint64_t)coin->clone.value;
 
        if (cost == 0)
            next_coin = NULL;
        else
            next_coin = find_next_coin(cost, &cointype);
 
        if (next_coin) {
            /* There will be at least one more string to add to the list,
             * use a comma.
             */
            stringbuffer_append_string(buf, ", ");
        } else {
            stringbuffer_append_string(buf, " and ");
        }
        if (num == 1)
            stringbuffer_append_printf(buf, "1 %s", coin->clone.name);
        else
            stringbuffer_append_printf(buf, "%u %ss", num, coin->clone.name);
    } while (next_coin);
 
done:
    return stringbuffer_finish(buf);
}
 
static StringBuffer *real_money_value(const object *coin, StringBuffer *buf) {
    assert(coin->type == MONEY);
    assert(buf);
 
    stringbuffer_append_printf(buf, "%ld %s", (long)coin->nrof, coin->nrof == 1 ? coin->name : coin->name_pl);
    return buf;
}
 
char *cost_str(uint64_t cost) {
    return cost_string_from_value(cost, LARGEST_COIN_GIVEN);
}
 
char *cost_approx_str(const object *tmp, object *who) {
    uint64_t approx_val = price_approx(tmp, who);
    int idskill1 = 0;
    int idskill2 = 0;
    const typedata *tmptype;
 
    StringBuffer *buf = stringbuffer_new();
 
    /* money it's pretty hard to not give the exact price, so skip all logic and just return the real value. */
    if (tmp->type == MONEY) {
        return stringbuffer_finish(real_money_value(tmp, buf));
    }
 
    tmptype = get_typedata(tmp->type);
    if (tmptype) {
        idskill1 = tmptype->identifyskill;
        idskill2 = tmptype->identifyskill2;
    }
 
    /* we show an approximate price if
     * 1) we are approximating
     * 2) there either is no id skill(s) for the item, or we don't have them
     * 3) we don't have bargaining skill either
     */
    if (!idskill1 || !find_skill_by_number(who, idskill1)) {
        if (!idskill2 || !find_skill_by_number(who, idskill2)) {
            if (!find_skill_by_number(who, SK_BARGAINING)) {
                int num;
                int cointype = LARGEST_COIN_GIVEN;
                archetype *coin = find_next_coin(approx_val, &cointype);
 
                if (coin == NULL) {
                    stringbuffer_append_string(buf, "nothing");
                    return stringbuffer_finish(buf);
                }
 
                num = approx_val/coin->clone.value;
                if (num == 1)
                    stringbuffer_append_printf(buf, "about one %s", coin->clone.name);
                else if (num < 5)
                    stringbuffer_append_printf(buf, "a few %s", coin->clone.name_pl);
                else if (num < 10)
                    stringbuffer_append_printf(buf, "several %s", coin->clone.name_pl);
                else if (num < 25)
                    stringbuffer_append_printf(buf, "a moderate amount of %s", coin->clone.name_pl);
                else if (num < 100)
                    stringbuffer_append_printf(buf, "lots of %s", coin->clone.name_pl);
                else if (num < 1000)
                    stringbuffer_append_printf(buf, "a great many %s", coin->clone.name_pl);
                else
                    stringbuffer_append_printf(buf, "a vast quantity of %s", coin->clone.name_pl);
                return stringbuffer_finish(buf);
            }
        }
    }
 
    // If we get here, return the price we guessed.
    stringbuffer_delete(buf);
    return cost_str(approx_val);
}
 
uint64_t query_money(const object *op) {
    uint64_t total = 0;
 
    if (op->type != PLAYER && op->type != CONTAINER) {
        LOG(llevError, "Query money called with non player/container\n");
        return 0;
    }
    FOR_INV_PREPARE(op, tmp) {
        if (tmp->type == MONEY) {
            total += (uint64_t)tmp->nrof*(uint64_t)tmp->value;
        } else if (tmp->type == CONTAINER
        && QUERY_FLAG(tmp, FLAG_APPLIED)
        && (tmp->race == NULL || strstr(tmp->race, "gold"))) {
            total += query_money(tmp);
        }
    } FOR_INV_FINISH();
    return total;
}
 
int pay_for_amount(uint64_t to_pay, object *pl) {
    if (to_pay == 0)
        return 1;
    if (to_pay > query_money(pl))
        return 0;
 
    to_pay = pay_from_container(pl, pl, to_pay);
 
    FOR_INV_PREPARE(pl, pouch) {
        if (to_pay <= 0)
            break;
        if (pouch->type == CONTAINER
        && QUERY_FLAG(pouch, FLAG_APPLIED)
        && (pouch->race == NULL || strstr(pouch->race, "gold"))) {
            to_pay = pay_from_container(pl, pouch, to_pay);
        }
    } FOR_INV_FINISH();
    if (to_pay > 0) {
        LOG(llevError, "pay_for_amount: Cannot remove enough money -- %" FMT64U " remains\n", to_pay);
    }
 
    fix_object(pl);
    return 1;
}
 
int pay_for_item(object *op, object *pl, uint64_t reduction) {
    uint64_t to_pay = shop_price_buy(op, pl);
    assert(to_pay >= reduction);
    to_pay -= reduction;
 
    if (to_pay == 0)
        return 1;
    if (to_pay > query_money(pl))
        return 0;
 
    to_pay = pay_from_container(pl, pl, to_pay);
 
    FOR_INV_PREPARE(pl, pouch) {
        if (to_pay <= 0)
            break;
        if (pouch->type == CONTAINER
        && QUERY_FLAG(pouch, FLAG_APPLIED)
        && (pouch->race == NULL || strstr(pouch->race, "gold"))) {
            to_pay = pay_from_container(pl, pouch, to_pay);
        }
    } FOR_INV_FINISH();
    if (to_pay > 0) {
        LOG(llevError, "pay_for_item: Cannot remove enough money -- %" FMT64U " remains\n", to_pay);
    }
    if (settings.real_wiz == FALSE && QUERY_FLAG(pl, FLAG_WAS_WIZ))
        SET_FLAG(op, FLAG_WAS_WIZ);
    fix_object(pl);
    return 1;
}
 
static int64_t remove_value(object *coin_objs[], int64_t remain) {
    int i;
 
    for (i = 0; i < NUM_COINS; i++) {
        int count;
        int64_t num_coins;
 
        if ((int64_t)coin_objs[i]->nrof * coin_objs[i]->value > remain) {
            num_coins = remain/coin_objs[i]->value;
            if ((uint64_t)num_coins*(uint64_t)coin_objs[i]->value < (uint64_t) remain) {
                num_coins++;
            }
        } else {
            num_coins = coin_objs[i]->nrof;
        }
        remain -= (int64_t)num_coins*(int64_t)coin_objs[i]->value;
        coin_objs[i]->nrof -= num_coins;
        /* Now start making change.  Start at the coin value
         * below the one we just did, and work down to
         * the lowest value.
         */
        count = i-1;
        while (remain < 0 && count >= 0) {
            num_coins = -remain/coin_objs[count]->value;
            coin_objs[count]->nrof += num_coins;
            remain += num_coins*coin_objs[count]->value;
            count--;
        }
    }
 
    return remain;
}
 
static void add_value(object *coin_objs[], int64_t value) {
    int i;
 
    for (i = NUM_COINS-LARGEST_COIN_GIVEN-1; i >= 0; i--) {
        uint32_t nrof;
 
        nrof = (uint32_t)(value/coin_objs[i]->value);
        value -= nrof*coin_objs[i]->value;
        coin_objs[i]->nrof += nrof;
    }
}
 
static void insert_objects(object *pl, object *container, object *objects[], int objects_len) {
    int i, one = 0;
 
    for (i = 0; i < objects_len; i++) {
        if (objects[i]->nrof > 0) {
            object_insert_in_ob(objects[i], container);
            one = 1;
        } else {
            object_free_drop_inventory(objects[i]);
        }
    }
    if (one)
        esrv_update_item(UPD_WEIGHT, pl, container);
}
 
static uint64_t pay_from_container(object *pl, object *pouch, uint64_t to_pay) {
    size_t i;
    int64_t remain;
    object *coin_objs[NUM_COINS];
    object *other_money[16]; /* collects MONEY objects not matching coins[] */
    size_t other_money_len; /* number of allocated entries in other_money[] */
    archetype *at;
 
    if (pouch->type != PLAYER && pouch->type != CONTAINER)
        return to_pay;
 
    remain = to_pay;
    for (i = 0; i < NUM_COINS; i++)
        coin_objs[i] = NULL;
 
    /* This hunk should remove all the money objects from the player/container */
    other_money_len = 0;
    FOR_INV_PREPARE(pouch, tmp) {
        if (tmp->type == MONEY) {
            for (i = 0; i < NUM_COINS; i++) {
                if (!strcmp(coins[NUM_COINS-1-i], tmp->arch->name)
                && (tmp->value == tmp->arch->clone.value)) {
                    /* This should not happen, but if it does, just
                     * merge the two.
                     */
                    if (coin_objs[i] != NULL) {
                        LOG(llevError, "%s has two money entries of (%s)\n", pouch->name, coins[NUM_COINS-1-i]);
                        object_remove(tmp);
                        coin_objs[i]->nrof += tmp->nrof;
                        object_free_drop_inventory(tmp);
                    } else {
                        object_remove(tmp);
                        coin_objs[i] = tmp;
                    }
                    break;
                }
            }
            if (i == NUM_COINS) {
                if (other_money_len >= sizeof(other_money)/sizeof(*other_money)) {
                    LOG(llevError, "pay_for_item: Cannot store non-standard money object %s\n", tmp->arch->name);
                } else {
                    object_remove(tmp);
                    other_money[other_money_len++] = tmp;
                }
            }
        }
    } FOR_INV_FINISH();
 
    /* Fill in any gaps in the coin_objs array - needed to make change.      */
    /* Note that the coin_objs array goes from least value to greatest value */
    for (i = 0; i < NUM_COINS; i++)
        if (coin_objs[i] == NULL) {
            at = find_archetype(coins[NUM_COINS-1-i]);
            if (at == NULL) {
                continue;
            }
            coin_objs[i] = object_new();
            object_copy(&at->clone, coin_objs[i]);
            coin_objs[i]->nrof = 0;
        }
 
    /* Try to pay from standard coins first. */
    remain = remove_value(coin_objs, remain);
 
    /* Now pay from non-standard coins until all is paid. */
    for (i = 0; i < other_money_len && remain > 0; i++) {
        uint32_t nrof;
        object *coin;
 
        coin = other_money[i];
 
        /* Find the minimal number of coins to use. This prevents converting
         * excess non-standard coins to standard money.
         */
        nrof = (remain+coin->value-1)/coin->value;
        if (nrof > coin->nrof) {
            nrof = coin->nrof;
        }
        coin->nrof -= nrof;
        add_value(coin_objs, nrof*coin->value);
 
        remain = remove_value(coin_objs, remain);
    }
 
    /* re-insert remaining coins into player */
    insert_objects(pl, pouch, coin_objs, NUM_COINS);
    insert_objects(pl, pouch, other_money, other_money_len);
 
    return(remain);
}
 
uint64_t add_with_overflow(uint64_t a, uint64_t b) {
    if (a == UINT64_MAX) {
        return a;
    }
 
    if (UINT64_MAX - a < b) {
        // Overflow
        return UINT64_MAX;
    } else {
        return a + b;
    }
}
 
struct unpaid_count {
    object *pl;
    int count;
    uint64_t price;
};
 
static void unpaid_iter(object *item, void (*callback)(object *item, void *data), void *data) {
    FOR_OB_AND_BELOW_PREPARE(item) {
        if (QUERY_FLAG(item, FLAG_UNPAID)) {
            callback(item, data);
        }
        if (item->inv) {
            unpaid_iter(item->inv, callback, data);
        }
    } FOR_OB_AND_BELOW_FINISH();
}
 
static void count_unpaid_callback(object *item, void *data) {
    struct unpaid_count *args = (struct unpaid_count *)data;
    args->count++;
    args->price = add_with_overflow(args->price, shop_price_buy(item, args->pl));
}
 
static void count_unpaid(object *pl, object *item, int *unpaid_count, uint64_t *unpaid_price) {
    struct unpaid_count args = {pl, 0, 0};
    unpaid_iter(item, count_unpaid_callback, &args);
    *unpaid_count = args.count;
    *unpaid_price = args.price;
}
 
static void count_coins(object *item, uint32_t *coincount) {
    FOR_OB_AND_BELOW_PREPARE(item) {
        /* Merely converting the player's monetary wealth won't do.
         * If we did that, we could print the wrong numbers for the
         * coins, so we count the money instead.
         */
        for (int i = 0; i < NUM_COINS; i++) {
            if (!strcmp(coins[i], item->arch->name)) {
                coincount[i] += item->nrof;
                break;
            }
        }
        if (item->inv) {
            count_coins(item->inv, coincount);
        }
    } FOR_OB_AND_BELOW_FINISH();
}
 
static uint64_t compute_price_variation_with_bargaining(object *pl, uint64_t price, float max_variation) {
    object *skill = find_skill_by_number(pl, SK_BARGAINING);
    if (skill && skill->level > 0) {
        return rndm(0, price * (max_variation * skill->level / settings.max_level));
    }
    return 0;
}
 
int can_pay(object *pl) {
    int unpaid_count = 0, i;
    uint64_t unpaid_price = 0;
    uint32_t coincount[NUM_COINS];
 
    if (!pl || pl->type != PLAYER) {
        LOG(llevError, "can_pay(): called against something that isn't a player\n");
        return 0;
    }
    uint64_t player_wealth = query_money(pl);
 
    for (i = 0; i < NUM_COINS; i++)
        coincount[i] = 0;
 
    count_unpaid(pl, pl->inv, &unpaid_count, &unpaid_price);
    count_coins(pl->inv, coincount);
 
    if (unpaid_price > player_wealth) {
        char buf[MAX_BUF], coinbuf[MAX_BUF];
        int denominations = 0;
        char *value = cost_str(unpaid_price);
 
        snprintf(buf, sizeof(buf), "You have %d unpaid items that would cost you %s, ", unpaid_count, value);
        free(value);
        for (i = 0; i < NUM_COINS; i++) {
            if (coincount[i] > 0 && coins[i]) {
                if (denominations == 0)
                    snprintf(buf+strlen(buf), sizeof(buf)-strlen(buf), "but you only have");
                denominations++;
                archetype *arch = find_archetype(coins[i]);
                if (arch != NULL)
                {
                    snprintf(coinbuf, sizeof(coinbuf), " %u %s,", coincount[i], arch->clone.name_pl);
                    snprintf(buf+strlen(buf), sizeof(buf)-strlen(buf), "%s", coinbuf);
                }
            }
        }
        if (denominations == 0)
            snprintf(buf+strlen(buf), sizeof(buf)-strlen(buf), "but you don't have any money.");
        else if (denominations > 1)
            make_list_like(buf);
        draw_ext_info(NDI_UNIQUE, 0, pl, MSG_TYPE_SHOP,
                      MSG_TYPE_SHOP_PAYMENT, buf);
        return 0;
    } else
        return 1;
}
 
static void shop_pay_unpaid_callback(object *op, void *data) {
    object *pl = (object *)data;
    char name_op[MAX_BUF];
    uint64_t price = shop_price_buy(op, pl);
    uint64_t reduction = 0;
    if (!object_value_set(op, "price")) {
        // only items without a player-set price can be bargained for
        reduction = compute_price_variation_with_bargaining(pl, price, MAX_BUY_REDUCTION);
    }
    if (!pay_for_item(op, pl, reduction)) {
        uint64_t i = price - query_money(pl);
        char *missing = cost_str(i);
 
        CLEAR_FLAG(op, FLAG_UNPAID);
        query_name(op, name_op, MAX_BUF);
        draw_ext_info_format(NDI_UNIQUE, 0, pl,
                             MSG_TYPE_SHOP, MSG_TYPE_SHOP_PAYMENT,
                             "You lack %s to buy %s.",
                             missing, name_op);
        free(missing);
        SET_FLAG(op, FLAG_UNPAID);
        return;
    } else {
        // TODO: Figure out how to pass in the shop owner for player shops.
        if (events_execute_object_event(op, EVENT_BOUGHT, pl, NULL, NULL, SCRIPT_FIX_ALL) != 0)
            return;
 
        object *tmp;
        char *value = cost_str(price - reduction);
 
        CLEAR_FLAG(op, FLAG_UNPAID);
        events_execute_global_event(EVENT_GBOUGHT, op, pl, price);
        CLEAR_FLAG(op, FLAG_PLAYER_SOLD);
        query_name(op, name_op, MAX_BUF);
 
        if (reduction > 0) {
            char *reduction_str = cost_str(reduction);
            draw_ext_info_format(NDI_UNIQUE, 0, pl,
                                 MSG_TYPE_SHOP, MSG_TYPE_SHOP_PAYMENT,
                                 "You paid %s for %s after bargaining a reduction of %s.",
                                 value, name_op, reduction_str);
            change_exp(pl, reduction, "bargaining", SK_EXP_NONE);
            free(reduction_str);
        } else {
            draw_ext_info_format(NDI_UNIQUE, 0, pl,
                                 MSG_TYPE_SHOP, MSG_TYPE_SHOP_PAYMENT,
                                 "You paid %s for %s.",
                                 value, name_op);
        }
        free(value);
        tmp = object_merge(op, NULL);
        if (pl->type == PLAYER && !tmp) {
            /* If item wasn't merged we update it. If merged, object_merge() handled everything for us. */
            esrv_update_item(UPD_FLAGS|UPD_NAME, pl, op);
        }
    }
}
 
int shop_pay_unpaid(object *pl, object *op) {
    if (!op) {
        return 1;
    }
    unpaid_iter(op, shop_pay_unpaid_callback, pl);
    return 1;
}
 
void sell_item(object *op, object *pl) {
    object *tmp;
    archetype *at;
    char obj_name[MAX_BUF];
 
    query_name(op, obj_name, MAX_BUF);
 
    if (pl == NULL || pl->type != PLAYER) {
        LOG(llevDebug, "Object other than player tried to sell something.\n");
        return;
    }
 
    if (events_execute_object_event(op, EVENT_SELLING, pl, NULL, NULL, SCRIPT_FIX_ALL) != 0)
        return;
 
    object_set_value(op, CUSTOM_NAME_FIELD, NULL, 0);
 
    uint64_t price = shop_price_sell(op, pl);
    if (price == 0) {
        draw_ext_info_format(NDI_UNIQUE, 0, pl,
                             MSG_TYPE_SHOP, MSG_TYPE_SHOP_SELL,
                             "We're not interested in %s.",
                             obj_name);
        return;
    }
    events_execute_global_event(EVENT_GSOLD, op, pl, price);
 
    int64_t extra_gain = compute_price_variation_with_bargaining(pl, price, MAX_SELL_EXTRA);
    char *value_str = cost_str(price + extra_gain);
 
    if (extra_gain > 0) {
        change_exp(pl, extra_gain, "bargaining", SK_EXP_NONE);
        char *extra_str = cost_str(extra_gain);
        draw_ext_info_format(NDI_UNIQUE, 0, pl, MSG_TYPE_SHOP, MSG_TYPE_SHOP_SELL,
                "You receive %s for %s, after bargaining for %s more than proposed.", value_str, obj_name, extra_str);
        free(extra_str);
        price += extra_gain;
    } else {
        draw_ext_info_format(NDI_UNIQUE, 0, pl, MSG_TYPE_SHOP, MSG_TYPE_SHOP_SELL,
                "You receive %s for %s.", value_str, obj_name);
    }
    free(value_str);
 
    for (int count = LARGEST_COIN_GIVEN; coins[count] != NULL; count++) {
        at = find_archetype(coins[count]);
        if (at == NULL)
            LOG(llevError, "Could not find %s archetype\n", coins[count]);
        else if ((price/at->clone.value) > 0) {
            FOR_INV_PREPARE(pl, pouch) {
                if (pouch->type == CONTAINER
                && QUERY_FLAG(pouch, FLAG_APPLIED)
                && pouch->race
                && strstr(pouch->race, "gold")) {
                    int w = at->clone.weight*(100-pouch->stats.Str)/100;
                    int n = price/at->clone.value;
 
                    if (w == 0)
                        w = 1;    /* Prevent divide by zero */
                    if (n > 0
                    && (!pouch->weight_limit || pouch->carrying+w <= pouch->weight_limit)) {
                        if (pouch->weight_limit
                        && (pouch->weight_limit-pouch->carrying)/w < n)
                            n = (pouch->weight_limit-pouch->carrying)/w;
 
                        tmp = object_new();
                        object_copy(&at->clone, tmp);
                        tmp->nrof = n;
                        price -= (uint64_t)tmp->nrof*(uint64_t)tmp->value;
                        tmp = object_insert_in_ob(tmp, pouch);
                        esrv_update_item(UPD_WEIGHT, pl, pl);
                    }
                }
            } FOR_INV_FINISH();
            if (price/at->clone.value > 0) {
                tmp = object_new();
                object_copy(&at->clone, tmp);
                tmp->nrof = price/tmp->value;
                price -= (uint64_t)tmp->nrof*(uint64_t)tmp->value;
                tmp = object_insert_in_ob(tmp, pl);
                esrv_update_item(UPD_WEIGHT, pl, pl);
            }
        }
    }
 
    if (price != 0) {
        LOG(llevError, "Warning - payment not zero: %" PRIo64 "\n", price);
    }
 
    SET_FLAG(op, FLAG_UNPAID);
    identify(op);
}
 
static double shop_specialisation_ratio(const object *item, const mapstruct *map) {
    shopitems *items = map->shopitems;
    double ratio = SPECIALISATION_EFFECT, likedness = 0.001;
    int i;
 
    if (item == NULL) {
        LOG(llevError, "shop_specialisation_ratio: passed a NULL item for map %s\n", map->path);
        return 0;
    }
    if (item->type == (uint8_t)-1) {
        LOG(llevError, "shop_specialisation_ratio: passed an item with an invalid type\n");
        /*
         * I'm not really sure what the /right/ thing to do here is,
         * these types of item shouldn't exist anyway, but returning
         * the ratio is probably the best bet.."
         */
        return ratio;
    }
    if (map->shopitems) {
        for (i = 0; i < items[0].index; i++)
            if (items[i].typenum == item->type || (items[i].typenum == -1 && likedness == 0.001))
                likedness = items[i].strength/100.0;
    }
    if (likedness > 1.0) { /* someone has been rather silly with the map headers. */
        LOG(llevDebug, "shop_specialisation ratio: item type %d on map %s is above 100%%\n", item->type, map->path);
        likedness = 1.0;
    }
    if (likedness < -1.0) {
        LOG(llevDebug, "shop_specialisation ratio: item type %d on map %s is below -100%%\n", item->type, map->path);
        likedness = -1.0;
    }
    ratio = ratio+(1.0-ratio)*likedness;
    if (ratio <= 0.1)
        ratio = 0.1; /* if the ratio were much lower than this, we would get silly prices */
    return ratio;
}
 
static double shop_greed(const mapstruct *map) {
    float greed = map->shopgreed;
    if (greed == 0) {
        greed = 1;
    }
    return tanh(-greed+2.0)/2 + 0.5;
}
 
double shop_approval(const mapstruct *map, const object *player) {
    double approval = 1.0;
    if (map->shoprace) {
        approval = NEUTRAL_RATIO;
        if (player->race && !strcmp(player->race, map->shoprace))
            approval = 1.0;
    }
    return approval;
}
 
static uint64_t value_limit(uint64_t val, int quantity, const object *who, int isshop) {
    uint64_t newval, unit_price;
    mapstruct *map;
 
    unit_price = val/quantity;
    if (!isshop || !who) {
        if (unit_price > 10000)
            newval = 8000+isqrt(unit_price)*20;
        else
            newval = unit_price;
    } else {
        if (!who->map) {
            LOG(llevError, "value_limit: asked shop price for ob %s on NULL map\n", who->name);
            return val;
        }
        map = who->map;
        if (map->shopmin && unit_price < map->shopmin)
            return 0;
        else if (unit_price > map->shopmax/2)
            newval = MIN((map->shopmax/2)+isqrt(unit_price-map->shopmax/2), map->shopmax);
        else if (unit_price > 10000)
            newval = 8000+isqrt(unit_price)*20;
        else
            newval = unit_price;
    }
    newval *= quantity;
    return newval;
}
 
int shop_describe(const object *op) {
    mapstruct *map = op->map;
    /*shopitems *items=map->shopitems;*/
    int pos = 0, i;
    double opinion = 0;
    char tmp[MAX_BUF] = "\0", *value;
 
    if (op->type != PLAYER)
        return 0;
 
    /*check if there is a shop specified for this map */
    if (map->shopitems
    || map->shopgreed
    || map->shoprace
    || map->shopmin
    || map->shopmax) {
        draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SHOP, MSG_TYPE_SHOP_LISTING,
                      "From looking at the nearby shop you determine that it trades in:");
 
        if (map->shopitems) {
            for (i = 0; i < map->shopitems[0].index; i++) {
                if (map->shopitems[i].name && map->shopitems[i].strength > 10) {
                    snprintf(tmp+pos, sizeof(tmp)-pos, "%s, ", map->shopitems[i].name_pl);
                    pos += strlen(tmp+pos);
                }
            }
        }
        if (!pos)
            strcpy(tmp, "a little of everything.");
 
        /* format the string into a list */
        make_list_like(tmp);
        draw_ext_info(NDI_UNIQUE, 0, op,
                      MSG_TYPE_SHOP, MSG_TYPE_SHOP_LISTING, tmp);
 
        if (map->shopmax) {
            value = cost_str(map->shopmax);
            draw_ext_info_format(NDI_UNIQUE, 0, op,
                                 MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                                 "It won't trade for items above %s.",
                                 value);
            free(value);
        }
 
        if (map->shopmin) {
            value = cost_str(map->shopmin);
            draw_ext_info_format(NDI_UNIQUE, 0, op,
                                 MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                                 "It won't trade in items worth less than %s.",
                                 value);
            free(value);
        }
 
        if (map->shopgreed) {
            if (map->shopgreed > 2.0)
                draw_ext_info(NDI_UNIQUE, 0, op,
                              MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                              "It tends to overcharge massively.");
            else if (map->shopgreed > 1.5)
                draw_ext_info(NDI_UNIQUE, 0, op,
                              MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                              "It tends to overcharge substantially.");
            else if (map->shopgreed > 1.1)
                draw_ext_info(NDI_UNIQUE, 0, op,
                              MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                              "It tends to overcharge slightly.");
            else if (map->shopgreed < 0.9)
                draw_ext_info(NDI_UNIQUE, 0, op,
                              MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                              "It tends to undercharge.");
        }
        if (map->shoprace) {
            opinion = shop_approval(map, op);
            if (opinion > 0.8)
                draw_ext_info(NDI_UNIQUE, 0, op,
                              MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                              "You think the shopkeeper likes you.");
            else if (opinion > 0.5)
                draw_ext_info(NDI_UNIQUE, 0, op,
                              MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                              "The shopkeeper seems unconcerned by you.");
            else
                draw_ext_info(NDI_UNIQUE, 0, op,
                              MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                              "The shopkeeper seems to have taken a dislike to you.");
        }
    } else draw_ext_info(NDI_UNIQUE, 0, op, MSG_TYPE_SHOP, MSG_TYPE_SHOP_MISC,
                             "There is no shop nearby.");
 
    return 1;
}