/*
 * meow_ui_view.c — meow_view 视图/页面框架骨架（§A 视图数据结构/嵌套/生命周期/页面导航）。
 *
 * meow_view 是**薄壳**：容器 + 生命周期 + 事件路由；叶子仍是 meow_widget（不改）。绘制走
 * z 序绘制物注册表（on_draw 回调，非保留——不缓存像素）。opt-in：不调 meow_view_* 的 App
 * 完全照旧（widget/activity/flush 不动）。页面模型 = 定案 b（顶层页切走 activity 栈，
 * page_push/pop/replace 包装；不做页内子导航栈，sub_push/pop 为预留扩展位 a 桩）。
 */
#include "meow_ui.h"
#include "meow_ui_internal.h"
#include "meow_ui_view.h"
#include <stdlib.h>
#include <string.h>

#define MEOW_VIEW_BY_ID_MAX 32

static meow_view *g_view_by_id[MEOW_VIEW_BY_ID_MAX];   /* id → 顶层页 view（page_push/pop 查找） */
static meow_view *g_top_view = NULL;                    /* 当前进入的顶层页 view（生命周期跟踪） */

static void run_fn(meow_view_fn f, meow_view *v)
{
    if (f) f(v, v->ctx);
}

/* 登记/清除 id→view 映射（幂等）。 */
static void view_map_set(meow_view *v)
{
    if (!v) return;
    int id = v->id;
    if (id >= 0 && id < MEOW_VIEW_BY_ID_MAX) g_view_by_id[id] = v;
}
static void view_map_clear(meow_view *v)
{
    if (!v) return;
    int id = v->id;
    if (id >= 0 && id < MEOW_VIEW_BY_ID_MAX && g_view_by_id[id] == v) g_view_by_id[id] = NULL;
}
static meow_view *view_map_get(int id)
{
    return (id >= 0 && id < MEOW_VIEW_BY_ID_MAX) ? g_view_by_id[id] : NULL;
}

/* 进入一个 view（置 ENTERED + on_enter）。 */
static void view_enter(meow_view *v)
{
    if (!v || (v->state & MEOW_VIEW_STATE_ENTERED)) return;
    v->state |= MEOW_VIEW_STATE_ENTERED;
    run_fn(v->hooks.on_enter, v);
}
/* 离开一个 view（清 ENTERED + on_leave；默认不销毁子 view/widget——弹回零重建）。 */
static void view_leave(meow_view *v)
{
    if (!v || !(v->state & MEOW_VIEW_STATE_ENTERED)) return;
    v->state &= ~MEOW_VIEW_STATE_ENTERED;
    run_fn(v->hooks.on_leave, v);
}

/* ============================================================ */
/* 生命周期                                                    */
/* ============================================================ */
meow_view *meow_view_create(int id, meow_view_type type,
                            const meow_view_hooks *hooks, void *ctx)
{
    meow_view *v = (meow_view *)calloc(1, sizeof *v);
    if (!v) return NULL;
    v->id = id;
    v->type = (type == MEOW_VIEW_CONTAINER) ? MEOW_VIEW_CONTAINER : MEOW_VIEW_ACTIVITY;
    v->x = v->y = v->w = v->h = 0;
    v->z = 0;
    v->state = MEOW_VIEW_STATE_CREATED;
    if (hooks) v->hooks = *hooks;
    v->ctx = ctx;
    view_map_set(v);
    meow_draw_view_register(v);                 /* 登记为绘制物（on_draw 经 z 序重画触发） */
    run_fn(v->hooks.on_create, v);
    if (v->hooks.on_layout) run_fn(v->hooks.on_layout, v);   /* 布局：create 后跑一次 */
    return v;
}

void meow_view_free(meow_view *v)
{
    if (!v) return;
    if (v->state & MEOW_VIEW_STATE_ENTERED) view_leave(v);
    run_fn(v->hooks.on_destroy, v);             /* 释放视图态资源 */
    view_map_clear(v);
    meow_draw_view_unregister(v);               /* 注销 z 序绘制物 */
    for (int i = 0; i < v->nwidgets; i++)       /* 叶子控件 */
        meow_widget_free(v->widgets[i]);
    v->nwidgets = 0;
    for (int i = 0; i < v->nchildren; i++)      /* 子 view 递归 */
        meow_view_free(v->children[i]);
    v->nchildren = 0;
    free(v);
}

/* ============================================================ */
/* 嵌套（组合视图树）                                          */
/* ============================================================ */
int meow_view_add_child(meow_view *parent, meow_view *child)
{
    if (!parent || !child || child == parent) return -1;
    for (int i = 0; i < parent->nchildren; i++)
        if (parent->children[i] == child) return -1;   /* 去重 */
    if (parent->nchildren >= MEOW_VIEW_MAX_CHILD) return -1;
    parent->children[parent->nchildren++] = child;
    child->parent = parent;
    return 0;
}

int meow_view_add_widget(meow_view *v, meow_widget *w)
{
    if (!v || !w) return -1;
    for (int i = 0; i < v->nwidgets; i++)
        if (v->widgets[i] == w) return -1;
    if (v->nwidgets >= MEOW_VIEW_MAX_WIDGET) return -1;
    v->widgets[v->nwidgets++] = w;
    meow_draw_widget_set_view(w, v);   /* z 深度源 = view 树；重算 auto z */
    return 0;
}

void meow_view_set_z(meow_view *v, int z)
{
    if (!v) return;
    v->z = (z < 0) ? 0 : z;
    meow_draw_view_set_z(v, v->z);
}
int meow_view_z(const meow_view *v)
{
    return v ? v->z : 0;
}

/* ============================================================ */
/* 页面导航（包装 activity 栈——唯一驱动 on_enter/on_leave）      */
/* ============================================================ */
void meow_view_page_push(int id)
{
    meow_view *cur = g_top_view;
    meow_view *next = view_map_get(id);
    if (cur && cur != next) view_leave(cur);
    meow_ui_activity_push(id);
    view_enter(next);
    g_top_view = next ? next : cur;
}

void meow_view_page_pop(void)
{
    meow_view *cur = g_top_view;
    view_leave(cur);
    meow_ui_activity_pop();
    meow_view *next = view_map_get(meow_ui_activity_active());
    view_enter(next);
    g_top_view = next ? next : NULL;
}

/* 说明（诚实）：replace 假定目标页已由 App 先 meow_view_create 指定 id 建好；本批不销毁旧页
 * 对象（保留弹回），仅 leave+enter 切换——与设计「leave+destroy 当前」的差异见汇报。 */
void meow_view_page_replace(int id)
{
    meow_view *cur = g_top_view;
    meow_view *next = view_map_get(id);
    if (cur && cur != next) view_leave(cur);
    view_enter(next);
    g_top_view = next ? next : cur;
}

/* ---- 页内子导航（预留扩展位 a 桩：本批不实现，仅返回占位）---- */
int meow_view_sub_push(meow_view *v, meow_view *sub)
{
    (void)v; (void)sub;
    return 0;   /* 预留：将来在 ACTIVITY view 内维护子栈 */
}
meow_view *meow_view_sub_pop(meow_view *v)
{
    (void)v;
    return NULL;   /* 预留 */
}

/* ============================================================ */
/* 坐标 / 查询                                                  */
/* ============================================================ */
int meow_view_screen_x(const meow_view *v)
{
    int x = v ? v->x : 0;
    const meow_view *p = v ? v->parent : NULL;
    while (p) { x += p->x; p = p->parent; }
    return x;
}
int meow_view_screen_y(const meow_view *v)
{
    int y = v ? v->y : 0;
    const meow_view *p = v ? v->parent : NULL;
    while (p) { y += p->y; p = p->parent; }
    return y;
}

meow_view *meow_view_parent(const meow_view *v) { return v ? v->parent : NULL; }
int meow_view_get_state(const meow_view *v) { return v ? (int)v->state : 0; }