/*
Copyright (c) 1998-2015, Enno Rehling <enno@eressea.de>
Katja Zedel <katze@felidae.kn-bremen.de
Christian Schlittchen <corwin@amber.kn-bremen.de>

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
**/

#include <platform.h>
#include <kernel/config.h>
#include "skill.h"

#include "curse.h"
#include "region.h"
#include "unit.h"

#include <kernel/attrib.h>
#include <util/goodies.h>
#include <util/language.h>
#include <util/log.h>
#include <util/rng.h>

/* libc includes */
#include <assert.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

/** skillmod attribut **/
static void init_skillmod(variant *var)
{
    var->v = calloc(sizeof(skillmod_data), 1);
}

/** temporary skill modification (NOT SAVED!). */
attrib_type at_skillmod = {
    "skillmod",
    init_skillmod,
    a_free_voidptr,
    NULL,
    NULL,                         /* can't write function pointers */
    NULL,                         /* can't read function pointers */
    NULL,
    ATF_PRESERVE
};

attrib *make_skillmod(skill_t sk, skillmod_fun special, double multiplier, int bonus)
{
    attrib *a = a_new(&at_skillmod);
    skillmod_data *smd = (skillmod_data *)a->data.v;

    smd->skill = sk;
    smd->special = special;
    smd->bonus = bonus;
    smd->multiplier = multiplier;

    return a;
}

int
skillmod(const unit * u, const region * r, skill_t sk, int value)
{
    const attrib * a = u->attribs;
    for (a = a_find((attrib *)a, &at_skillmod); a && a->type == &at_skillmod;
        a = a->next) {
        skillmod_data *smd = (skillmod_data *)a->data.v;
        if (smd->skill != NOSKILL && smd->skill != sk)
            continue;
        if (smd->special) {
            value = smd->special(u, r, sk, value);
            if (value < 0)
                return value;           /* pass errors back to caller */
        }
        if (smd->multiplier)
            value = (int)(value * smd->multiplier);
        value += smd->bonus;
    }
    return value;
}

int level_days(int level)
{
    /* FIXME STUDYDAYS * ((level + 1) * level / 2); */
    return 30 * ((level + 1) * level / 2);
}

int level(int days)
{
    int i;
    static int ldays[64];
    static bool init = false;
    if (!init) {
        init = true;
        for (i = 0; i != 64; ++i)
            ldays[i] = level_days(i + 1);
    }
    for (i = 0; i != 64; ++i)
        if (ldays[i] > days)
            return i;
    return i;
}

void sk_set(skill * sv, int level)
{
    assert(sv && level != 0);
    sv->weeks = skill_weeks(level);
    sv->level = level;
    assert(sv->weeks <= sv->level * 2 + 1);
}

static bool rule_random_progress(void)
{
    static int rule, config;
    if (config_changed(&config)) {
        rule = config_get_int("study.random_progress", 1);
    }
    return rule != 0;
}

int skill_weeks(int level)
/* how many weeks must i study to get from level to level+1 */
{
    if (rule_random_progress()) {
        int coins = 2 * level;
        int heads = 1;
        while (coins--) {
            heads += rng_int() % 2;
        }
        return heads;
    }
    return level + 1;
}

void increase_skill(unit * u, skill_t sk, int weeks)
{
    skill *sv = unit_skill(u, sk);
    assert(weeks >= 0);
    if (!sv) {
        sv = add_skill(u, sk);
    }
    while (sv->weeks <= weeks) {
        weeks -= sv->weeks;
        sk_set(sv, sv->level + 1);
    }
    sv->weeks -= weeks;
    assert(sv->weeks <= sv->level * 2 + 1);
}

void reduce_skill(unit * u, skill * sv, int weeks)
{
    int max_weeks = sv->level + 1;

    assert(weeks >= 0);
    if (rule_random_progress()) {
        max_weeks += sv->level;
    }
    sv->weeks += weeks;
    while (sv->level > 0 && sv->weeks > max_weeks) {
        sv->weeks -= sv->level;
        --sv->level;
        max_weeks -= 2;
    }
    if (sv->level == 0) {
        /* reroll */
        sv->weeks = skill_weeks(sv->level);
    }
    assert(sv->weeks <= sv->level * 2 + 1);
}

int skill_compare(const skill * sk, const skill * sc)
{
    if (sk->level > sc->level)
        return 1;
    if (sk->level < sc->level)
        return -1;
    if (sk->weeks < sc->weeks)
        return 1;
    if (sk->weeks > sc->weeks)
        return -1;
    return 0;
}