/*
 *  File:       skills.cc
 *  Summary:    Skill exercising functions.
 *  Written by: Linley Henzell
 *
 *  Change History (most recent first):
 *
 *       <3>     8/08/99        BWR             Increased skill cost in midgame
 *
 *       <2>     7/31/99        BWR             Inc skill_point granularity,
 *                                                  added MAX_SPENDING_LIMIT
 *       <1>     -/--/--        LRH             Created
 */

#include "AppHdr.h"
#include "skills.h"

#include <string.h>
#include <stdlib.h>

#include "externs.h"

#include "macro.h"
#include "player.h"
#include "skills2.h"
#include "stuff.h"


// MAX_COST_LIMIT is the maximum XP amount it will cost to raise a skill
//                by 10 skill points (ie one standard practice).
//
// MAX_SPENDING_LIMIT is the maximum XP amount we allow the player to 
//                    spend on a skill in a single raise.
//
// Note that they don't have to be equal, but it is important to make 
// sure that they're set so that the spending limit will always allow
// for 1 skill point to be earned.
#define MAX_COST_LIMIT           250
#define MAX_SPENDING_LIMIT       250

static void exercise2( char exsk );

// These values were calculated by running a simulation of gaining skills.
// The goal is to try and match the old cost system which used the player's
// experience level (which has a number of problems) so things shouldn't 
// seem too different to the player... but we still try to err on the 
// high side for the lower levels. -- bwr
int skill_cost_needed( int level )
{
    // The average starting skill total is actually lower, but 
    // some classes get about 2200, and they would probably be 
    // start around skill cost level 3 if we used the average.  -- bwr
    int ret = 2200; 

    switch (level)
    {
    case 1: ret = 0; break;

    case 2:  ret +=   250; break; //  250 -- big because of initial 25 pool
    case 3:  ret +=   350; break; //  100
    case 4:  ret +=   550; break; //  200
    case 5:  ret +=   900; break; //  350
    case 6:  ret +=  1300; break; //  400
    case 7:  ret +=  1900; break; //  600
    case 8:  ret +=  2800; break; //  900
    case 9:  ret +=  4200; break; // 1400
    case 10: ret +=  5900; break; // 1700
    case 11: ret +=  9000; break; // 3100

    default:
        ret += 9000 + (4000 * (level - 11));
        break;
    }

    return (ret);
}

void calc_total_skill_points( void )
{
    int i;

    you.total_skill_points = 0;

    for (i = 0; i < NUM_SKILLS; i++)
    {   
        you.total_skill_points += you.skill_points[i];
    }

    for (i = 1; i <= 27; i++) 
    {
        if (you.total_skill_points < skill_cost_needed(i)) 
            break;
    } 

    you.skill_cost_level = i - 1;

#if DEBUG_DIAGNOSTICS
    you.redraw_experience = 1;
#endif
}

// skill_cost_level makes skills more expensive for more experienced characters
// skill_level      makes higher skills more expensive 
static int calc_skill_cost( int skill_cost_level, int skill_level )
{
    int ret = 1 + skill_level;    

    // does not yet allow for loss of skill levels.
    if (skill_level > 9)
    {
        ret *= (skill_level - 7);
        ret /= 3;
    }

    if (skill_cost_level > 4)
        ret += skill_cost_level - 4;
    if (skill_cost_level > 7)
        ret += skill_cost_level - 7;
    if (skill_cost_level > 10)
        ret += skill_cost_level - 10;
    if (skill_cost_level > 13)
        ret += skill_cost_level - 13;
    if (skill_cost_level > 16)
        ret += skill_cost_level - 16;

    if (skill_cost_level > 10)
    {
        ret *= (skill_cost_level - 5);
        ret /= 5;
    }

    if (skill_level > 7)
        ret += 1;
    if (skill_level > 9)
        ret += 2;
    if (skill_level > 11)
        ret += 3;
    if (skill_level > 13)
        ret += 4;
    if (skill_level > 15)
        ret += 5;

    if (ret > MAX_COST_LIMIT)
        ret = MAX_COST_LIMIT;

    return (ret);
}

void exercise(char exsk, int deg)
{
    if (you.exp_available > 0 && you.skills[exsk] < 27)
    {
        while (deg > 0)
        {
            if (!you.practise_skill[exsk] && !one_chance_in(4))
                break;

            exercise2( exsk );
            deg--;
        }
    }

    return;
}                               // end exercise()

static void exercise2( char exsk )
{
    int deg = 1;
    int bonus = 0;
    char old_best_skill = best_skill(SK_FIGHTING, (NUM_SKILLS - 1), 99);

    int skill_change = calc_skill_cost(you.skill_cost_level, you.skills[exsk]);
    int i;

    // being good at some weapons makes others easier to learn:
    if (exsk < SK_SLINGS)
    {
        /* blades to blades */
        if ((exsk == SK_SHORT_BLADES || exsk == SK_LONG_SWORDS)
            && (you.skills[SK_SHORT_BLADES] > you.skills[exsk]
                || you.skills[SK_LONG_SWORDS] > you.skills[exsk]))
        {
            bonus += random2(3);
        }

        /* Axes and Polearms */
        if ((exsk == SK_AXES || exsk == SK_POLEARMS)
            && (you.skills[SK_AXES] > you.skills[exsk]
                || you.skills[SK_POLEARMS] > you.skills[exsk]))
        {
            bonus += random2(3);
        }

        /* Polearms and Staves */
        if ((exsk == SK_POLEARMS || exsk == SK_STAVES)
            && (you.skills[SK_POLEARMS] > you.skills[exsk]
                || you.skills[SK_STAVES] > you.skills[exsk]))
        {
            bonus += random2(3);
        }

        /* Axes and Maces */
        if ((exsk == SK_AXES || exsk == SK_MACES_FLAILS)
            && (you.skills[SK_AXES] > you.skills[exsk]
                || you.skills[SK_MACES_FLAILS] > you.skills[exsk]))
        {
            bonus += random2(3);
        }
    }

    // Quick fix for the fact that stealth can't be gained fast enough to
    // keep up with the monster levels, this should speed its advancement
    if (exsk == SK_STEALTH)
        bonus += random2(3);

    // spell casting is cheaper early on, and elementals hinder each other
    if (exsk >= SK_SPELLCASTING)
    {
        if (you.skill_cost_level < 5)
        {
            skill_change /= 2;
        }
        else if (you.skill_cost_level < 15)
        {
            skill_change *= (10 + (you.skill_cost_level - 5));
            skill_change /= 20;
        }

        // being good at elemental magic makes other elements harder to learn:
        if (exsk >= SK_FIRE_MAGIC && exsk <= SK_EARTH_MAGIC
            && (you.skills[SK_FIRE_MAGIC] > you.skills[exsk]
                || you.skills[SK_ICE_MAGIC] > you.skills[exsk]
                || you.skills[SK_AIR_MAGIC] > you.skills[exsk]
                || you.skills[SK_EARTH_MAGIC] > you.skills[exsk]))
        {
            if (one_chance_in(3))
                return;
        }

        // some are direct opposites
        if ((exsk == SK_FIRE_MAGIC || exsk == SK_ICE_MAGIC)
            && (you.skills[SK_FIRE_MAGIC] > you.skills[exsk]
                || you.skills[SK_ICE_MAGIC] > you.skills[exsk]))
        {
            // of course, this is cumulative with the one above.
            if (!one_chance_in(3))
                return;
        }

        if ((exsk == SK_AIR_MAGIC || exsk == SK_EARTH_MAGIC)
            && (you.skills[SK_AIR_MAGIC] > you.skills[exsk]
                || you.skills[SK_EARTH_MAGIC] > you.skills[exsk]))
        {
            if (!one_chance_in(3))
                return;
        }

        // experimental restriction (too many spell schools) -- bwr
        int skill_rank = 1;

        for (i  = SK_CONJURATIONS; i <= SK_DIVINATIONS; i++)
        {
            if (you.skills[exsk] < you.skills[i])
                skill_rank++;
        }

        // Things get progressively harder, but not harder than
        // the Fire-Air or Ice-Earth level.
        if (skill_rank > 3 && one_chance_in(10 - skill_rank))
            return;
    }

    int fraction = 0;
    int spending_limit = (you.exp_available < MAX_SPENDING_LIMIT) 
                                    ? you.exp_available : MAX_SPENDING_LIMIT;

    // handle fractional learning
    if (skill_change > spending_limit)
    {
        // This system is a bit hard on missile weapons in the late game
        // since they require expendable ammo in order to practise.
        // Increasing the "deg"ree of exercise would make missile
        // weapons too easy earlier on, so instead we're giving them
        // a special case here.
        if ((exsk != SK_DARTS && exsk != SK_BOWS && exsk != SK_CROSSBOWS)
                                        || skill_change > you.exp_available)
        {
            fraction = (spending_limit * 10) / skill_change;
            skill_change = (skill_change * fraction) / 10;

            deg = (deg * fraction) / 10;

            if (deg == 0)
                bonus = (bonus * fraction) / 10;
        }
        else
        {
            if ((skill_change / 2) > MAX_SPENDING_LIMIT)
            {
                deg = 0;
                fraction = 5;
            }
            else
            {
                deg = 1;
            }

            skill_change = spending_limit;
        }
    }

    skill_change -= random2(5);

    if (skill_change < 1)
    {
        // No free lunch, this is a problem now that we don't
        // have overspending.
        if (deg > 0 || fraction > 0 || bonus > 0)
            skill_change = 1;
        else
            skill_change = 0;
    }

    // Can safely return at any stage before this
    int skill_inc = (deg + bonus) * 10 + fraction;

    // Starting to learn skills is easier if the appropriate stat is high
    if (you.skills[exsk] == 0)
    {
        if ((exsk >= SK_FIGHTING && exsk <= SK_STAVES) || exsk == SK_ARMOUR)
        {
            // These skills are easier for the strong
            skill_inc *= ((you.strength < 5) ? 5 : you.strength);
            skill_inc /= 10;
        }
        else if (exsk >= SK_SLINGS && exsk <= SK_UNARMED_COMBAT)
        {
            // These skills are easier for the dexterous
            // Note: Armour is handled above.
            skill_inc *= ((you.dex < 5) ? 5 : you.dex);
            skill_inc /= 10;
        }
        else if (exsk >= SK_SPELLCASTING && exsk <= SK_POISON_MAGIC)
        {
            // These skills are easier for the smart
            skill_inc *= ((you.intel < 5) ? 5 : you.intel);
            skill_inc /= 10;
        }
    }

    you.skill_points[exsk] += skill_inc;
    you.exp_available -= skill_change;

    you.total_skill_points += skill_inc;
    if (you.skill_cost_level < 27
       && you.total_skill_points >= skill_cost_needed(you.skill_cost_level + 1))
    {
        you.skill_cost_level++;
    }     

    if (you.exp_available < 0)
        you.exp_available = 0;

    you.redraw_experience = 1;

/*
    New (LH): debugging bit: when you exercise a skill, displays the skill
    exercised and how much you spent on it. Too irritating to be a regular 
    WIZARD feature.

#if DEBUG_DIAGNOSTICS
    snprintf( info, INFO_SIZE, "Exercised %s * %d for %d xp.", 
             skill_name(exsk), skill_inc, skill_change );
    mpr( info, MSGCH_DIAGNOSTICS );
#endif
*/

    if (you.skill_points[exsk] >
                    (skill_exp_needed(you.skills[exsk] + 2) 
                            * species_skills(exsk, you.species) / 100))
    {
        strcpy(info, "Your ");
        strcat(info, skill_name(exsk));
        strcat(info, " skill increases!");
        mpr(info, MSGCH_INTRINSIC_GAIN);

        you.skills[exsk]++;

        // Recalculate this skill's order for tie breaking skills 
        // at its new level.   See skills2.cc::init_skill_order()
        // for more details.  -- bwr
        you.skill_order[exsk] = 0;
        for (i = SK_FIGHTING; i < NUM_SKILLS; i++)
        {
            if (i == exsk)
                continue;

            if (you.skills[i] >= you.skills[exsk])
                you.skill_order[exsk]++;
        }

        if (exsk == SK_FIGHTING)
            calc_hp();

        if (exsk == SK_INVOCATIONS || exsk == SK_EVOCATIONS 
            || exsk == SK_SPELLCASTING)
        {
            calc_mp();
        }

        if (exsk == SK_DODGING || exsk == SK_ARMOUR)
            you.redraw_evasion = 1;

        if (exsk == SK_ARMOUR || exsk == SK_SHIELDS 
                || exsk == SK_ICE_MAGIC || exsk == SK_EARTH_MAGIC
                || you.duration[ DUR_TRANSFORMATION ] > 0)
        {
            you.redraw_armour_class = 1;
        }

        const unsigned char best = best_skill( SK_FIGHTING, 
                                               (NUM_SKILLS - 1), 99 );

        const unsigned char best_spell = best_skill( SK_SPELLCASTING, 
                                                     SK_POISON_MAGIC, 99 );

        if ((exsk == SK_SPELLCASTING) 
                && (you.skills[exsk] == 1 && best_spell == SK_SPELLCASTING))
        {
            mpr("You're starting to get the hang of this magic thing.");
        }

        if (best != old_best_skill || old_best_skill == exsk)
        {
            redraw_skill( you.your_name, player_title() );
        }
    }
}                               // end exercise2()