/*
 * meow_ui_anim.c — 动画基座 + UI 节拍器（§12.2）。
 *
 * 时间驱动 tween：start 记录起始时刻（meow_ui_time_ms，单调），tick 按经过时间求 t，
 * 代入 ease 得 v = from + (to-from)*ease(t)，回调 update；t 到 1 → 回调 done(canceled=0) 并回收。
 * 取消 → 回调 done(canceled=1) 并回收。静态池（≤MEOW_ANIM_MAX），热路径零 malloc。
 * 无动画时 meow_anim_tick() 仅查活动计数即返回（零开销）。
 *
 * 节拍挂接：由 meow_ui_run 主循环（on_tick 之后）与 meow_ui_feed_tick（阻塞 IME 循环）调用，
 * 不引入常驻高频轮询。modal/dialog 阻塞循环不喂 tick（动画暂停，符合「模态期不做动画」惯例）。
 */
#include "meow_ui.h"
#include "include/meow_ui_anim.h"
#include <string.h>

struct meow_anim {
    int                active;
    float              from, to;
    uint32_t           duration_ms;
    meow_ease          ease;
    uint64_t           start_ms;
    float              value;
    int                region_set;
    int                rx, ry, rw, rh;
    meow_anim_update_fn update;
    meow_anim_done_fn   done;
    void              *ctx;
};

static struct meow_anim g_pool[MEOW_ANIM_MAX];
static unsigned g_active = 0;   /* 活动动画计数（0 = 空闲，tick 直退） */

/* ---- 缓动 ---- */
float meow_ease_apply(meow_ease e, float t)
{
    if (e == MEOW_EASE_OUT) {
        /* ease-out quad */
        float u = 1.0f - t;
        return 1.0f - u * u;
    }
    if (e == MEOW_EASE_IN_OUT) {
        /* ease-in-out quad */
        if (t < 0.5f) return 2.0f * t * t;
        float u = -2.0f * t + 2.0f;
        return 1.0f - u * u * 0.5f;
    }
    if (e == MEOW_EASE_OVERSHOOT) {
        /* ease-out-back（越过目标再回稳）；t=1 → 恰为 1 */
        const float c1 = 1.70158f;
        const float c3 = c1 + 1.0f;
        float u = t - 1.0f;
        return 1.0f + c3 * u * u * u + c1 * u * u;
    }
    /* MEOW_EASE_LINEAR */
    return t;
}

/* ---- 生命周期 ---- */
meow_anim *meow_anim_start(const meow_anim_desc *d)
{
    if (!d) return NULL;
    for (int i = 0; i < MEOW_ANIM_MAX; i++) {
        struct meow_anim *a = &g_pool[i];
        if (a->active) continue;
        a->active = 1;
        a->from = d->from;
        a->to = d->to;
        a->duration_ms = d->duration_ms ? d->duration_ms : 1;   /* 0 → 瞬发（下一 tick 完成） */
        a->ease = d->ease;
        a->start_ms = meow_ui_time_ms();
        a->update = d->update;
        a->done = d->done;
        a->ctx = d->ctx;
        a->region_set = 0;
        a->value = d->from;
        g_active++;
        if (a->update) a->update(a, a->value, a->ctx);   /* 起始帧回调（t=0） */
        return a;
    }
    return NULL;   /* 池满 */
}

void meow_anim_cancel(meow_anim *a)
{
    if (!a || !a->active) return;
    a->active = 0;
    if (g_active > 0) g_active--;
    if (a->done) a->done(a, 1, a->ctx);
}

int meow_anim_active(meow_anim *a) { return (a && a->active) ? 1 : 0; }
float meow_anim_value(meow_anim *a) { return a ? a->value : 0.0f; }

void meow_anim_set_region(meow_anim *a, int x, int y, int w, int h)
{
    if (!a) return;
    if (x < 0) { a->region_set = 0; return; }
    a->region_set = 1;
    a->rx = x; a->ry = y; a->rw = w > 0 ? w : 0; a->rh = h > 0 ? h : 0;
}

/* ---- 节拍器 ---- */
unsigned meow_anim_count(void) { return (unsigned)g_active; }

void meow_anim_tick(void)
{
    if (g_active == 0) return;   /* 无动画：零开销直接返回 */
    uint64_t now = meow_ui_time_ms();
    for (int i = 0; i < MEOW_ANIM_MAX; i++) {
        struct meow_anim *a = &g_pool[i];
        if (!a->active) continue;
        uint64_t elapsed = now - a->start_ms;
        float t = (float)(elapsed) / (float)a->duration_ms;
        int finished = (t >= 1.0f);
        if (t > 1.0f) t = 1.0f;
        if (t < 0.0f) t = 0.0f;
        float v = a->from + (a->to - a->from) * meow_ease_apply(a->ease, t);
        a->value = v;
        if (a->update) a->update(a, v, a->ctx);
        if (a->region_set && a->rw > 0 && a->rh > 0)
            meow_ui_flush_region(a->rx, a->ry, a->rw, a->rh);   /* 只刷动画影响区 */
        if (finished) {
            a->active = 0;
            if (g_active > 0) g_active--;
            if (a->done) a->done(a, 0, a->ctx);
        }
    }
}