/* SPDX-License-Identifier: MIT */
/*
 * konbattle.c
 *
 * Copyright (c) 2026 KonAki
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include "konbattle.h"

#include <math.h>
#include <string.h>

/*** random numbers ***/

static uint32_t next(kon_battle_t *bt)
{
	uint32_t x = bt->seed;

	x ^= x << 13;
	x ^= x >> 17;
	x ^= x << 5;
	bt->seed = x;
	return x;
}

/* 0 up to but not including n */
static int below(kon_battle_t *bt, int n)
{
	return n > 1 ? (int)(next(bt) % (uint32_t)n) : 0;
}

static int percent(kon_battle_t *bt, int chance)
{
	return below(bt, 100) < chance;
}

/*** formulas ***/

enum {
	F_NUM, F_A, F_B, F_VAR, F_NEG, F_NOT,
	F_ADD, F_SUB, F_MUL, F_DIV, F_MOD, F_POW, F_LT, F_GT, F_LE, F_GE, F_EQ, F_NE, F_AND, F_OR, F_SELECT,
	F_FLOOR, F_CEIL, F_ROUND, F_ABS, F_SQRT, F_MAX, F_MIN
};

#define FORMULA_STACK 32
#define FORMULA_DEPTH 24

typedef struct parser {
	kon_formula_t *f;
	const char *s;
	int at, depth, stack, ok;
} parser_t;

static void fail(parser_t *p)
{
	if (p->ok) p->f->errorAt = p->at;
	p->ok = 0;
}

static void emit(parser_t *p, int op, double n, int pushes)
{
	if (!p->ok) return;
	if (p->f->count >= (int)(sizeof p->f->ops / sizeof p->f->ops[0])) {
		fail(p);
		return;
	}
	p->f->ops[p->f->count].op = op;
	p->f->ops[p->f->count].n = n;
	p->f->count++;
	p->stack += pushes;
	if (p->stack > FORMULA_STACK || p->stack < 1) fail(p);
}

static void space(parser_t *p)
{
	while (p->s[p->at] == ' ' || p->s[p->at] == '\t' || p->s[p->at] == '\n' || p->s[p->at] == '\r') p->at++;
}

static int accept(parser_t *p, const char *token)
{
	size_t n = strlen(token);

	space(p);
	if (strncmp(p->s + p->at, token, n) != 0) return 0;
	p->at += (int)n;
	return 1;
}

static int isWord(int c)
{
	return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_';
}

static int word(parser_t *p, char *out, int size)
{
	int n = 0;

	space(p);
	while (isWord((unsigned char)p->s[p->at])) {
		if (n + 1 < size) out[n++] = p->s[p->at];
		p->at++;
	}
	out[n] = '\0';
	return n;
}

static void expression(parser_t *p);

static int statNumber(const char *name)
{
	static const char *names[KON_STATS] = {"mhp", "mmp", "atk", "def", "mat", "mdf", "agi", "luk", "hp", "mp", "tp", "level"};
	int i;

	for (i = 0; i < KON_STATS; i++) {
		if (strcmp(name, names[i]) == 0) return i;
	}
	return -1;
}

static void primary(parser_t *p)
{
	char w[32];

	space(p);
	if (!p->ok) return;
	if (p->depth++ > FORMULA_DEPTH) {
		fail(p);
		return;
	}
	if (accept(p, "(")) {
		expression(p);
		if (!accept(p, ")")) fail(p);
	} else if ((p->s[p->at] >= '0' && p->s[p->at] <= '9') || p->s[p->at] == '.') {
		double v = 0.0, scale = 1.0;
		int digits = 0;

		while (p->s[p->at] >= '0' && p->s[p->at] <= '9') {
			v = v * 10.0 + (double)(p->s[p->at++] - '0');
			digits++;
		}
		if (p->s[p->at] == '.') {
			p->at++;
			while (p->s[p->at] >= '0' && p->s[p->at] <= '9') {
				scale *= 0.1;
				v += (double)(p->s[p->at++] - '0') * scale;
				digits++;
			}
		}
		if (!digits) fail(p);
		emit(p, F_NUM, v, 1);
	} else if (word(p, w, sizeof w)) {
		if ((strcmp(w, "a") == 0 || strcmp(w, "b") == 0) && accept(p, ".")) {
			char stat[32];
			int n;

			if (!word(p, stat, sizeof stat) || (n = statNumber(stat)) < 0) fail(p);
			else emit(p, w[0] == 'a' ? F_A : F_B, (double)n, 1);
		} else if (strcmp(w, "v") == 0 && accept(p, "[")) {
			expression(p);
			if (!accept(p, "]")) fail(p);
			emit(p, F_VAR, 0.0, 0);
		} else if (strcmp(w, "Math") == 0 && accept(p, ".")) {
			static const struct { const char *name; int op, args; } fns[] = {
				{"floor", F_FLOOR, 1}, {"ceil", F_CEIL, 1}, {"round", F_ROUND, 1}, {"abs", F_ABS, 1}, {"sqrt", F_SQRT, 1},
				{"max", F_MAX, 2}, {"min", F_MIN, 2}, {"pow", F_POW, 2}
			};
			size_t i;
			int found = -1;

			if (!word(p, w, sizeof w)) fail(p);
			for (i = 0; i < sizeof fns / sizeof fns[0]; i++) {
				if (strcmp(w, fns[i].name) == 0) found = (int)i;
			}
			if (found < 0 || !accept(p, "(")) {
				fail(p);
			} else {
				expression(p);
				if (fns[found].args == 2) {
					if (!accept(p, ",")) fail(p);
					expression(p);
				}
				if (!accept(p, ")")) fail(p);
				emit(p, fns[found].op, 0.0, fns[found].args == 2 ? -1 : 0);
			}
		} else {
			fail(p);
		}
	} else {
		fail(p);
	}
	p->depth--;
}

static void unary(parser_t *p)
{
	space(p);
	if (!p->ok) return;
	if (p->depth++ > FORMULA_DEPTH) {
		fail(p);
		return;
	}
	if (accept(p, "-")) {
		unary(p);
		emit(p, F_NEG, 0.0, 0);
	} else if (accept(p, "+")) {
		unary(p);
	} else if (p->s[p->at] == '!' && p->s[p->at + 1] != '=') {
		p->at++;
		unary(p);
		emit(p, F_NOT, 0.0, 0);
	} else {
		primary(p);
	}
	p->depth--;
}

/* ** goes right to left and binds tighter than the minus in front of it */
static void power(parser_t *p)
{
	unary(p);
	space(p);
	if (p->s[p->at] == '*' && p->s[p->at + 1] == '*') {
		p->at += 2;
		if (p->depth++ > FORMULA_DEPTH) {
			fail(p);
			return;
		}
		power(p);
		p->depth--;
		emit(p, F_POW, 0.0, -1);
	}
}

static void product(parser_t *p)
{
	power(p);
	for (;;) {
		int op;

		space(p);
		if (p->s[p->at] == '*' && p->s[p->at + 1] != '*') op = F_MUL;
		else if (p->s[p->at] == '/') op = F_DIV;
		else if (p->s[p->at] == '%') op = F_MOD;
		else return;
		p->at++;
		power(p);
		emit(p, op, 0.0, -1);
	}
}

static void sum(parser_t *p)
{
	product(p);
	for (;;) {
		int op;

		space(p);
		if (p->s[p->at] == '+') op = F_ADD;
		else if (p->s[p->at] == '-') op = F_SUB;
		else return;
		p->at++;
		product(p);
		emit(p, op, 0.0, -1);
	}
}

static void relation(parser_t *p)
{
	sum(p);
	for (;;) {
		int op;

		if (accept(p, "<=")) op = F_LE;
		else if (accept(p, ">=")) op = F_GE;
		else if (accept(p, "<")) op = F_LT;
		else if (accept(p, ">")) op = F_GT;
		else return;
		sum(p);
		emit(p, op, 0.0, -1);
	}
}

static void equality(parser_t *p)
{
	relation(p);
	for (;;) {
		int op;

		if (accept(p, "===") || accept(p, "==")) op = F_EQ;
		else if (accept(p, "!==") || accept(p, "!=")) op = F_NE;
		else return;
		relation(p);
		emit(p, op, 0.0, -1);
	}
}

static void conjunction(parser_t *p)
{
	equality(p);
	while (accept(p, "&&")) {
		equality(p);
		emit(p, F_AND, 0.0, -1);
	}
}

static void disjunction(parser_t *p)
{
	conjunction(p);
	while (accept(p, "||")) {
		conjunction(p);
		emit(p, F_OR, 0.0, -1);
	}
}

static void expression(parser_t *p)
{
	disjunction(p);
	if (accept(p, "?")) {
		if (p->depth++ > FORMULA_DEPTH) {
			fail(p);
			return;
		}
		expression(p);
		if (!accept(p, ":")) fail(p);
		expression(p);
		p->depth--;
		emit(p, F_SELECT, 0.0, -2);
	}
}

int kon_formulaCompile(kon_formula_t *f, const char *text)
{
	parser_t p;

	memset(f, 0, sizeof *f);
	f->errorAt = -1;
	if (!text) {
		f->errorAt = 0;
		return 0;
	}
	p.f = f;
	p.s = text;
	p.at = p.depth = p.stack = 0;
	p.ok = 1;
	expression(&p);
	space(&p);
	if (p.ok && text[p.at] != '\0') fail(&p);
	if (p.ok && p.stack != 1) fail(&p);
	if (!p.ok) {
		f->count = 0;
		return 0;
	}
	return 1;
}

static double sane(double v)
{
	if (!(v == v)) return 0.0;
	if (v > 1e12) return 1e12;
	if (v < -1e12) return -1e12;
	return v;
}

double kon_formulaEval(const kon_formula_t *f, const kon_battle_t *battle, const kon_battler_t *a, const kon_battler_t *b)
{
	double st[FORMULA_STACK + 2];
	int sp = 0, i;

	if (f->count <= 0) return 0.0;
	for (i = 0; i < f->count; i++) {
		int op = f->ops[i].op;
		double x, y;

		switch (op) {
		case F_NUM:
			st[sp++] = f->ops[i].n;
			break;
		case F_A:
		case F_B: {
			const kon_battler_t *who = op == F_A ? a : b;

			st[sp++] = who ? (double)kon_battlerStat(battle, who, (int)f->ops[i].n) : 0.0;
			break;
		}
		case F_VAR: {
			double n = st[sp - 1];
			int id = n >= 0.0 && n < 1e9 ? (int)n : -1;

			st[sp - 1] = battle->vars && id >= 0 && id < battle->varCount ? (double)battle->vars[id] : 0.0;
			break;
		}
		case F_NEG: st[sp - 1] = -st[sp - 1]; break;
		case F_NOT: st[sp - 1] = st[sp - 1] == 0.0 ? 1.0 : 0.0; break;
		case F_FLOOR: st[sp - 1] = floor(st[sp - 1]); break;
		case F_CEIL: st[sp - 1] = ceil(st[sp - 1]); break;
		case F_ROUND: st[sp - 1] = floor(st[sp - 1] + 0.5); break;
		case F_ABS: st[sp - 1] = fabs(st[sp - 1]); break;
		case F_SQRT: st[sp - 1] = st[sp - 1] > 0.0 ? sqrt(st[sp - 1]) : 0.0; break;
		case F_SELECT:
			x = st[sp - 3] != 0.0 ? st[sp - 2] : st[sp - 1];
			sp -= 2;
			st[sp - 1] = x;
			break;
		default:
			y = st[--sp];
			x = st[sp - 1];
			switch (op) {
			case F_ADD: x = x + y; break;
			case F_SUB: x = x - y; break;
			case F_MUL: x = x * y; break;
			case F_DIV: x = y != 0.0 ? x / y : 0.0; break;
			case F_MOD: x = y != 0.0 ? fmod(x, y) : 0.0; break;
			case F_POW: x = pow(x, y); break;
			case F_LT: x = x < y; break;
			case F_GT: x = x > y; break;
			case F_LE: x = x <= y; break;
			case F_GE: x = x >= y; break;
			case F_EQ: x = x == y; break;
			case F_NE: x = x != y; break;
			case F_AND: x = x != 0.0 && y != 0.0; break;
			case F_OR: x = x != 0.0 || y != 0.0; break;
			case F_MAX: x = x > y ? x : y; break;
			case F_MIN: x = x < y ? x : y; break;
			}
			st[sp - 1] = x;
			break;
		}
		st[sp - 1] = sane(st[sp - 1]);
	}
	return sp == 1 ? st[0] : 0.0;
}

/*** battlers ***/

void kon_battlerInit(kon_battler_t *b, const char *name, int team, int level)
{
	kon_battler_t zero = {0};
	int i;

	*b = zero;
	b->name = name;
	b->team = team == KON_ENEMIES ? KON_ENEMIES : KON_PARTY;
	b->level = level;
	b->hit = 95;
	b->pdr = b->mdr = 100;
	for (i = 0; i < KON_ELEMENTS; i++) b->elementRate[i] = 100;
}

int kon_battlerHasState(const kon_battler_t *b, int id)
{
	int i;

	for (i = 0; i < b->stateCount; i++) {
		if (b->states[i].id == id) return 1;
	}
	return 0;
}

static const kon_state_t *stateOf(const kon_battle_t *battle, int id)
{
	return id >= 0 && id < battle->stateCount && battle->states ? &battle->states[id] : NULL;
}

int kon_battlerStat(const kon_battle_t *battle, const kon_battler_t *b, int stat)
{
	long value, change = 0;
	int i;

	switch (stat) {
	case KON_STAT_HP: return b->hp;
	case KON_STAT_MP: return b->mp;
	case KON_STAT_TP: return b->tp;
	case KON_STAT_LEVEL: return b->level;
	}
	if (stat < 0 || stat >= KON_PARAMS) return 0;
	for (i = 0; i < b->stateCount; i++) {
		const kon_state_t *s = stateOf(battle, b->states[i].id);

		if (s) change += s->percent[stat];
	}
	if (change < -100) change = -100;
	if (change > 10000) change = 10000;
	value = ((long)b->base[stat] + b->plus[stat]) * (100 + change) / 100;
	if (value < (stat == KON_STAT_MHP ? 1 : 0)) value = stat == KON_STAT_MHP ? 1 : 0;
	if (value > 99999999L) value = 99999999L;
	return (int)value;
}

int kon_battlerAlive(const kon_battle_t *battle, const kon_battler_t *b)
{
	int i;

	if (b->hp <= 0) return 0;
	for (i = 0; i < b->stateCount; i++) {
		const kon_state_t *s = stateOf(battle, b->states[i].id);

		if (s && s->death) return 0;
	}
	return 1;
}

static void clampBattler(const kon_battle_t *battle, kon_battler_t *b)
{
	int mhp = kon_battlerStat(battle, b, KON_STAT_MHP), mmp = kon_battlerStat(battle, b, KON_STAT_MMP);

	if (b->hp > mhp) b->hp = mhp;
	if (b->hp < 0) b->hp = 0;
	if (b->mp > mmp) b->mp = mmp;
	if (b->mp < 0) b->mp = 0;
	if (b->tp > 100) b->tp = 100;
	if (b->tp < 0) b->tp = 0;
}

static int deathState(const kon_battle_t *battle)
{
	int i;

	for (i = 0; i < battle->stateCount; i++) {
		if (battle->states[i].death) return i;
	}
	return -1;
}

static int removeState(kon_battler_t *b, int id)
{
	int i;

	for (i = 0; i < b->stateCount; i++) {
		if (b->states[i].id == id) {
			b->states[i] = b->states[--b->stateCount];
			return 1;
		}
	}
	return 0;
}

static int addState(kon_battle_t *bt, kon_battler_t *b, int id)
{
	const kon_state_t *s = stateOf(bt, id);
	int i, turns = 0;

	if (!s) return 0;
	if (s->death) {
		b->hp = 0;
		b->stateCount = 0;
	} else if (!kon_battlerAlive(bt, b)) {
		return 0;
	}
	if (s->removeAt && s->turnsMax > 0) {
		int lo = s->turnsMin > 0 ? s->turnsMin : 1;

		turns = s->turnsMax > lo ? lo + below(bt, s->turnsMax - lo + 1) : lo;
	}
	for (i = 0; i < b->stateCount; i++) {
		if (b->states[i].id == id) {
			b->states[i].turns = turns;
			return 1;
		}
	}
	if (b->stateCount >= KON_BATTLER_STATES) return 0;
	b->states[b->stateCount].id = id;
	b->states[b->stateCount].turns = turns;
	b->stateCount++;
	return 1;
}

/*** skills ***/

int kon_skillCompile(kon_skill_t *skill)
{
	if (!skill->formulaText || !skill->formulaText[0]) {
		memset(&skill->formula, 0, sizeof skill->formula);
		skill->formula.errorAt = -1;
		return 1;
	}
	return kon_formulaCompile(&skill->formula, skill->formulaText);
}

/*** battle ***/

void kon_battleInit(kon_battle_t *bt, kon_battler_t *battlers, int count, const kon_state_t *states, int stateCount, uint32_t seed)
{
	kon_battle_t zero = {0};

	*bt = zero;
	bt->battlers = battlers;
	bt->count = battlers && count > 0 ? (count > KON_BATTLE_MAX ? KON_BATTLE_MAX : count) : 0;
	bt->states = states;
	bt->stateCount = states && stateCount > 0 ? stateCount : 0;
	bt->seed = seed ? seed : 0x9E3779B9u;
	bt->escapeRatio = -1.0f;
}

static int aliveNumber(const kon_battle_t *bt, int i)
{
	return i >= 0 && i < bt->count && kon_battlerAlive(bt, &bt->battlers[i]);
}

/* the battlers that can be hit by a scope for a user. returns how many, written to out */
static int friends(const kon_battle_t *bt, int user, int wantAlive, int *out)
{
	int i, n = 0;

	for (i = 0; i < bt->count; i++) {
		if (bt->battlers[i].team == bt->battlers[user].team && aliveNumber(bt, i) == wantAlive) out[n++] = i;
	}
	return n;
}

static int foes(const kon_battle_t *bt, int user, int *out)
{
	int i, n = 0;

	for (i = 0; i < bt->count; i++) {
		if (bt->battlers[i].team != bt->battlers[user].team && aliveNumber(bt, i)) out[n++] = i;
	}
	return n;
}

static int targets(kon_battle_t *bt, int user, const kon_skill_t *skill, int target, int *out)
{
	int list[KON_BATTLE_MAX], n, i, count = 0;

	if (bt->forced > 0 && (skill->scope == KON_SCOPE_ONE_ENEMY || skill->scope == KON_SCOPE_ONE_ALLY || skill->scope == KON_SCOPE_RANDOM_ENEMY)) {
		out[0] = bt->forced - 1;
		return 1;
	}
	switch (skill->scope) {
	case KON_SCOPE_USER:
		out[count++] = user;
		break;
	case KON_SCOPE_ALL_ENEMIES:
		count = foes(bt, user, out);
		break;
	case KON_SCOPE_ALL_ALLIES:
		count = friends(bt, user, 1, out);
		break;
	case KON_SCOPE_ALL_ALLIES_DEAD:
		count = friends(bt, user, 0, out);
		break;
	case KON_SCOPE_ONE_ENEMY:
		n = foes(bt, user, list);
		if (n == 0) break;
		if (target >= 0 && target < bt->count && bt->battlers[target].team != bt->battlers[user].team && aliveNumber(bt, target)) out[count++] = target;
		else out[count++] = list[below(bt, n)];
		break;
	case KON_SCOPE_RANDOM_ENEMY:
		n = foes(bt, user, list);
		for (i = 0; n > 0 && i < (skill->randomCount > 0 ? skill->randomCount : 1) && i < KON_BATTLE_MAX; i++) out[count++] = list[below(bt, n)];
		break;
	case KON_SCOPE_ONE_ALLY:
		n = friends(bt, user, 1, list);
		if (n == 0) break;
		if (target >= 0 && target < bt->count && bt->battlers[target].team == bt->battlers[user].team && aliveNumber(bt, target)) out[count++] = target;
		else out[count++] = list[below(bt, n)];
		break;
	case KON_SCOPE_ONE_ALLY_DEAD:
		n = friends(bt, user, 0, list);
		if (n == 0) break;
		if (target >= 0 && target < bt->count && bt->battlers[target].team == bt->battlers[user].team && !aliveNumber(bt, target)) out[count++] = target;
		else out[count++] = list[below(bt, n)];
		break;
	default:
		break;
	}
	return count;
}

static void resultInit(kon_result_t *r, int user, int target)
{
	kon_result_t zero = {0};

	*r = zero;
	r->user = user;
	r->target = target;
}

static void noteAdded(kon_result_t *r, int id)
{
	if (r->addedCount < KON_SKILL_STATES) r->added[r->addedCount++] = id;
}

static void noteRemoved(kon_result_t *r, int id)
{
	if (r->removedCount < KON_SKILL_STATES) r->removed[r->removedCount++] = id;
}

static int stateNoted(kon_battle_t *bt, kon_battler_t *t, int id, kon_result_t *r)
{
	int had = kon_battlerHasState(t, id);

	if (addState(bt, t, id)) {
		if (!had) noteAdded(r, id);
		return 1;
	}
	return 0;
}

/* death follows hp: dying clears the other states, coming back removes death */
static void settle(kon_battle_t *bt, kon_battler_t *t, kon_result_t *r)
{
	int death = deathState(bt);

	clampBattler(bt, t);
	if (death < 0) return;
	if (t->hp <= 0 && !kon_battlerHasState(t, death)) {
		stateNoted(bt, t, death, r);
		r->died = 1;
	} else if (t->hp > 0 && kon_battlerHasState(t, death)) {
		removeState(t, death);
		noteRemoved(r, death);
		r->revived = 1;
	}
}

static void hit(kon_battle_t *bt, int user, const kon_skill_t *skill, int target, kon_result_t *r)
{
	kon_battler_t *u = &bt->battlers[user], *t = &bt->battlers[target];
	int success = skill->successRate > 0 ? skill->successRate : 100;
	double value;
	int i, dmg;

	resultInit(r, user, target);

	if (skill->hitType == KON_HIT_PHYSICAL) {
		success = success * u->hit / 100;
		if (!percent(bt, success)) {
			r->missed = 1;
			return;
		}
		if (percent(bt, t->eva)) {
			r->evaded = 1;
			return;
		}
	} else if (skill->hitType == KON_HIT_MAGICAL) {
		if (!percent(bt, success)) {
			r->missed = 1;
			return;
		}
		if (percent(bt, t->mev)) {
			r->evaded = 1;
			return;
		}
	} else if (!percent(bt, success)) {
		r->missed = 1;
		return;
	}

	if (skill->damageType != KON_DAMAGE_NONE) {
		int recover = skill->damageType == KON_DAMAGE_HP_RECOVER || skill->damageType == KON_DAMAGE_MP_RECOVER;
		int amp;

		value = kon_formulaEval(&skill->formula, bt, u, t);
		if (skill->element > 0 && skill->element < KON_ELEMENTS) value = value * (double)t->elementRate[skill->element] / 100.0;
		if (value > 0.0) {
			if (skill->hitType == KON_HIT_PHYSICAL) value = value * (double)t->pdr / 100.0;
			else if (skill->hitType == KON_HIT_MAGICAL) value = value * (double)t->mdr / 100.0;
		}
		if (recover) value = -value;
		if (skill->critical && !recover && percent(bt, u->cri * (100 - t->cev) / 100)) {
			value *= 3.0;
			r->critical = 1;
		}
		if (value > 0.0 && t->guarding) value /= 2.0;
		amp = (int)floor(fabs(value) * (double)skill->variance / 100.0);
		if (amp > 0) value += (double)(below(bt, amp + 1) + below(bt, amp + 1) - amp);
		dmg = (int)floor(value + 0.5);
		if (dmg > 99999999) dmg = 99999999;
		if (dmg < -99999999) dmg = -99999999;

		switch (skill->damageType) {
		case KON_DAMAGE_HP:
		case KON_DAMAGE_HP_RECOVER:
		case KON_DAMAGE_HP_DRAIN: {
			int before = t->hp;

			t->hp -= dmg;
			clampBattler(bt, t);
			r->hp = t->hp - before;
			if (skill->damageType == KON_DAMAGE_HP_DRAIN) {
				int ub = u->hp;

				u->hp += -r->hp;
				clampBattler(bt, u);
				r->userHp = u->hp - ub;
			}
			break;
		}
		default: {
			int before = t->mp;

			t->mp -= dmg;
			clampBattler(bt, t);
			r->mp = t->mp - before;
			if (skill->damageType == KON_DAMAGE_MP_DRAIN) {
				int ub = u->mp;

				u->mp += -r->mp;
				clampBattler(bt, u);
				r->userMp = u->mp - ub;
			}
			break;
		}
		}
		if (r->hp < 0 && t->hp > 0) {
			for (i = t->stateCount - 1; i >= 0; i--) {
				const kon_state_t *s = stateOf(bt, t->states[i].id);

				if (s && s->removeByDamage > 0 && percent(bt, s->removeByDamage)) {
					noteRemoved(r, t->states[i].id);
					removeState(t, t->states[i].id);
				}
			}
		}
	}
	settle(bt, t, r);

	for (i = 0; i < skill->addStateCount && i < KON_SKILL_STATES; i++) {
		if (percent(bt, skill->addState[i].chance)) {
			if (stateNoted(bt, t, skill->addState[i].id, r) && t->hp <= 0) r->died = 1;
		}
	}
	for (i = 0; i < skill->removeStateCount && i < KON_SKILL_STATES; i++) {
		if (removeState(t, skill->removeState[i])) noteRemoved(r, skill->removeState[i]);
	}
	settle(bt, t, r);
	u->tp += skill->tpGain;
	clampBattler(bt, u);
}

int kon_battleUse(kon_battle_t *bt, int user, const kon_skill_t *skill, int target, kon_result_t *out, int cap)
{
	int list[KON_BATTLE_MAX], n, i, rep, made = 0, repeats;
	kon_battler_t *u;

	if (!bt || !skill || user < 0 || user >= bt->count || !aliveNumber(bt, user)) return -1;
	u = &bt->battlers[user];
	if (u->mp < skill->mpCost || u->tp < skill->tpCost) return -1;
	u->mp -= skill->mpCost;
	u->tp -= skill->tpCost;

	n = targets(bt, user, skill, target, list);
	repeats = skill->repeats > 0 ? skill->repeats : 1;
	for (i = 0; i < n; i++) {
		for (rep = 0; rep < repeats; rep++) {
			kon_result_t scratch;

			hit(bt, user, skill, list[i], made < cap && out ? &out[made] : &scratch);
			made++;
		}
	}
	return made < cap ? made : (cap > 0 ? cap : 0);
}

/*** turns ***/

int kon_battleQueue(kon_battle_t *bt, int kind, int battler, const kon_skill_t *skill, int target)
{
	kon_action_t *a;

	if (!bt || bt->queued >= KON_BATTLE_QUEUE || battler < 0 || battler >= bt->count) return 0;
	if (kind != KON_ACT_SKILL && kind != KON_ACT_GUARD && kind != KON_ACT_ESCAPE) return 0;
	if (kind == KON_ACT_SKILL && !skill) return 0;
	a = &bt->queue[bt->queued++];
	a->kind = kind;
	a->battler = battler;
	a->skill = skill;
	a->target = target;
	a->speed = 0;
	bt->sorted = 0;
	return 1;
}

static void sortQueue(kon_battle_t *bt)
{
	int i, j;

	for (i = 0; i < bt->queued; i++) {
		kon_action_t *a = &bt->queue[i];
		int agi = kon_battlerStat(bt, &bt->battlers[a->battler], KON_STAT_AGI);

		a->speed = agi + below(bt, 5 + agi / 4);
		if (a->kind == KON_ACT_GUARD) a->speed += 2000;
		else if (a->kind == KON_ACT_SKILL) a->speed += a->skill->speed;
	}
	for (i = 1; i < bt->queued; i++) {
		kon_action_t held = bt->queue[i];

		for (j = i - 1; j >= 0 && bt->queue[j].speed < held.speed; j--) bt->queue[j + 1] = bt->queue[j];
		bt->queue[j + 1] = held;
	}
	bt->sorted = 1;
	bt->next = 0;
}

static int restriction(const kon_battle_t *bt, const kon_battler_t *b)
{
	int i;

	for (i = 0; i < b->stateCount; i++) {
		const kon_state_t *s = stateOf(bt, b->states[i].id);

		if (s && s->restriction) return s->restriction;
	}
	return 0;
}

static float agility(const kon_battle_t *bt, int team)
{
	long total = 0;
	int i, n = 0;

	for (i = 0; i < bt->count; i++) {
		if (bt->battlers[i].team == team && kon_battlerAlive(bt, &bt->battlers[i])) {
			total += kon_battlerStat(bt, &bt->battlers[i], KON_STAT_AGI);
			n++;
		}
	}
	return n ? (float)total / (float)n : 0.0f;
}

static int escape(kon_battle_t *bt, int user, kon_result_t *out, int cap)
{
	kon_result_t r;
	float party = agility(bt, KON_PARTY), enemies = agility(bt, KON_ENEMIES);

	if (bt->escapeRatio < 0.0f) bt->escapeRatio = enemies > 0.0f ? 0.5f * party / enemies : 1.0f;
	resultInit(&r, user, -1);
	if ((float)below(bt, 10000) < bt->escapeRatio * 10000.0f) {
		r.escape = 2;
		bt->escaped = 1;
	} else {
		r.escape = 1;
		bt->escapeRatio += 0.1f;
	}
	if (cap > 0 && out) out[0] = r;
	return cap > 0 ? 1 : 0;
}

static void afterAction(kon_battle_t *bt, int user)
{
	kon_battler_t *b = &bt->battlers[user];
	int i;

	for (i = b->stateCount - 1; i >= 0; i--) {
		const kon_state_t *s = stateOf(bt, b->states[i].id);

		if (s && s->removeAt == 1 && b->states[i].turns > 0 && --b->states[i].turns == 0) removeState(b, b->states[i].id);
	}
}

int kon_battleNext(kon_battle_t *bt, kon_result_t *out, int cap)
{
	if (!bt) return -1;
	if (!bt->sorted) sortQueue(bt);
	while (bt->next < bt->queued) {
		kon_action_t a = bt->queue[bt->next++];
		kon_battler_t *u = &bt->battlers[a.battler];
		int n = 0, r;

		if (!kon_battlerAlive(bt, u)) continue;
		r = restriction(bt, u);
		if (r == 4) continue;
		if (r >= 1 && r <= 3 && a.kind != KON_ACT_GUARD) {
			int pool[KON_BATTLE_MAX], count = 0, i;

			for (i = 0; i < bt->count; i++) {
				int same = bt->battlers[i].team == u->team;

				if (!aliveNumber(bt, i)) continue;
				if (r == 2 || (r == 1 && !same) || (r == 3 && same)) pool[count++] = i;
			}
			if (!bt->attack || count == 0) continue;
			a.kind = KON_ACT_SKILL;
			a.skill = bt->attack;
			a.target = pool[below(bt, count)];
		}
		bt->last = a;
		if (a.kind == KON_ACT_GUARD) {
			u->guarding = 1;
		} else if (a.kind == KON_ACT_ESCAPE) {
			n = escape(bt, a.battler, out, cap);
		} else {
			bt->forced = r >= 1 && r <= 3 ? a.target + 1 : 0;
			n = kon_battleUse(bt, a.battler, a.skill, a.target, out, cap);
			bt->forced = 0;
			if (n < 0) n = 0;
		}
		afterAction(bt, a.battler);
		return n;
	}
	return -1;
}

int kon_battleEndTurn(kon_battle_t *bt, kon_result_t *out, int cap)
{
	int i, made = 0;

	if (!bt) return 0;
	for (i = 0; i < bt->count; i++) {
		kon_battler_t *b = &bt->battlers[i];
		kon_result_t r;
		int mhp, mmp, j;

		b->guarding = 0;
		if (!kon_battlerAlive(bt, b)) continue;
		resultInit(&r, i, i);
		mhp = kon_battlerStat(bt, b, KON_STAT_MHP);
		mmp = kon_battlerStat(bt, b, KON_STAT_MMP);
		{
			int hp = b->hp, mp = b->mp;

			b->hp += (int)((long)mhp * b->hrg / 100);
			b->mp += (int)((long)mmp * b->mrg / 100);
			b->tp += b->trg;
			clampBattler(bt, b);
			r.hp = b->hp - hp;
			r.mp = b->mp - mp;
		}
		for (j = b->stateCount - 1; j >= 0; j--) {
			const kon_state_t *s = stateOf(bt, b->states[j].id);

			if (s && s->removeAt == 2 && b->states[j].turns > 0 && --b->states[j].turns == 0) {
				noteRemoved(&r, b->states[j].id);
				removeState(b, b->states[j].id);
			}
		}
		settle(bt, b, &r);
		if (r.hp || r.mp || r.removedCount || r.died) {
			if (made < cap && out) out[made] = r;
			made++;
		}
	}
	bt->turn++;
	bt->queued = bt->next = bt->sorted = 0;
	return made < cap ? made : (cap > 0 ? cap : 0);
}

void kon_battleEnd(kon_battle_t *bt)
{
	int i, j;

	if (!bt) return;
	for (i = 0; i < bt->count; i++) {
		kon_battler_t *b = &bt->battlers[i];

		b->guarding = 0;
		for (j = b->stateCount - 1; j >= 0; j--) {
			const kon_state_t *s = stateOf(bt, b->states[j].id);

			if (s && s->removeAtBattleEnd && !s->death) removeState(b, b->states[j].id);
		}
		clampBattler(bt, b);
	}
	bt->queued = bt->next = bt->sorted = 0;
}

kon_outcome_t kon_battleOutcome(const kon_battle_t *bt)
{
	int i, party = 0, enemies = 0;

	if (bt->escaped) return KON_BATTLE_ESCAPED;
	for (i = 0; i < bt->count; i++) {
		if (!kon_battlerAlive(bt, &bt->battlers[i])) continue;
		if (bt->battlers[i].team == KON_PARTY) party++;
		else enemies++;
	}
	if (party == 0) return KON_BATTLE_DEFEAT;
	if (enemies == 0) return KON_BATTLE_VICTORY;
	return KON_BATTLE_ONGOING;
}