/* ui/reader/reader.c — 阅读器页（ACT_READER，全屏）：左右翻页模式。
 *
 * 用户口径：优先流畅度，其次功能。翻页路径不解码、不重排：
 *   - 后台 pthread 解码窗口（当前 ±1 页），主循环只取已备好的图；
 *   - 跟手拖动只 blit 两张已缓存页图，松手后 meow_anim 一次短滑动吸附（150ms）；
 *   - 只 flush 受影响区（本页=整屏内容区）；翻页/解码/驻留耗时都 meow_log 打点。
 *
 * 页源：logic/reader/page_source 的 mr_book 契约（count/meta/open/close）。目录册
 * （文件夹即书）是第一个实现；zip 册与条漫只需另写 provider / 消费方式，本页零改动。
 * 方向：一律读 M3 的 mr_reader_get_direction()（默认 RTL），不另立全局。
 *
 * 手势（与 SDK 语义对齐，见 sdk/meow_ui_input.c touch_release）：
 *   - 左缘（x<24）向右划 = 系统返回（MEOW_SWIPE_LEFT）→ 不消费，app.c page_pop 退出；
 *   - 屏底 28px 上滑 = 系统回桌面（MEOW_EV_HOME），SDK 不分发给 App，本页不起手；
 *   - 中部横拖 = 跟手翻页（本页用 app.c 路由来的原始 down/move 自己算位移）；
 *   - tap 分区方向感知：屏左/右 1/3 = 上/下一页，中 1/3 = chrome 显隐；双击 = 放大。
 *   - 物理键不映射（app.c 只记日志）。
 *
 * 节拍：app.c 的 on_tick 只转给 library_on_tick（不在本页 scope）。本页用一条常驻
 *   meow_anim “ticker”（SDK 主循环每轮 meow_anim_tick）驱动结果收取与双击判定超时，
 *   不新增常驻轮询线程，也不改 on_tick 路由。翻页动画本身也走同一节拍。
 *
 * 生命周期：on_enter 建状态 + 建 TopAppBar + 预取首页；on_leave 全量释放（停解码线程、
 *   释放全部页图/册索引/控件）。控件在 on_enter 建 → owner=ACT_READER（非根页防泄漏）。
 */
#include "tuku_internal.h"
#include "ui/reader/reader.h"
#include "logic/reader/page_source.h"
#include "logic/reader/nav.h"

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

#define MR_WIN            3       /* 预解码窗口：当前 ±1 页 */
#define MR_TOPBAR_H       56
#define MR_SLIDE_MS       150     /* 松手后一次短滑动吸附 */
#define MR_BOUNCE_MS      120     /* 未过阈值回弹 */
#define MR_DOUBLE_MS      240     /* 单击等待窗口（区分双击） */
#define MR_ZOOM_PCT       200     /* 双击放大倍率 */
#define MR_TICK_MS        16
#define MR_PAINT_MS       16      /* 跟手拖动重绘节流（≈60fps 上限） */
#define MR_DRAG_SLOP      8       /* 小于此位移算点击 */
#define MR_ZOOM_TEMP_CAP  (6 * 1024 * 1024)   /* 缩放临时缓冲软上限（>此值降倍率，保内存） */

#define MR_REQ_MAX        8
#define MR_RES_MAX        4

/* view on_event 的事件号不在公共头（sdk/meow_ui_internal.h §6.4）；本页只用到 SWIPE=3。 */
#define MR_EV_SWIPE       3

static mr_page_ctrl g_ctrl;
static char g_dir[MR_PATH_MAX];

static mr_dir_book g_db;
static mr_book g_book;
static int g_count;                 /* 0=空册/不可读 */
static int g_open_err;
static int g_page;

static int g_vw, g_vh;              /* 内容视口 = 全屏 */
static int g_fit = MR_FIT_WIDTH;
static int g_zoom_pct = 100;
static int g_pan_x, g_pan_y;
static int g_chrome = 1;
static meow_widget *g_tb;

/* ---- 页图缓存（≤3 张 downscale 后的图）---- */
typedef struct page_slot {
    int       idx;                  /* -1=空 */
    meow_img *img;                  /* 已 downscale 的页图 */
    int       src_w, src_h;
} page_slot;
static page_slot g_slot[MR_WIN];

/* ---- 后台解码队列 ---- */
typedef struct page_req { int idx; unsigned gen; } page_req;
typedef struct page_res { int idx; unsigned gen; meow_img *img; } page_res;

static pthread_t g_worker;
static pthread_mutex_t g_lock = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t  g_cv = PTHREAD_COND_INITIALIZER;
static int g_worker_on, g_stop;
static unsigned g_gen = 1;

static page_req g_req[MR_REQ_MAX];
static int g_req_head, g_req_tail, g_req_n;
static page_res g_res[MR_RES_MAX];
static int g_res_n;

/* ---- 节拍/动画 ---- */
static meow_anim *g_ticker;
static meow_anim *g_snap;           /* 翻页滑动吸附 */
static meow_anim *g_bounce;         /* 未过阈值回弹 */
static int g_slide_delta;           /* 翻页目标增量（动画中） */
static int g_slide_from;            /* 进场页起点（px） */
static int g_anim_v;                /* 进场页当前位移（px） */
static uint64_t g_flip_t0;
static uint64_t g_last_tick;
static uint64_t g_last_paint;
static int g_quitting;              /* on_leave 期间抑制回调 */

/* ---- 跟手拖动 ---- */
static int g_dragging;              /* 1=本次按下正在拖动 */
static int g_drag_mode;             /* 0=无 1=横滑翻页 2=放大平移 */
static int g_drag_x0, g_drag_y0;
static int g_drag_off;              /* 当前页水平位移（px） */
static int g_drag_pan_x0, g_drag_pan_y0;
static int g_touch_moved;           /* 本次按下是否已产生 >slop 的位移 */

/* ---- 单击延迟（双击判定窗口）---- */
static int g_tap_pending;
static int g_tap_x, g_tap_y;
static uint64_t g_tap_ms;
static uint64_t g_last_tap_ms;              /* 上一次点击（跨按下保持，双击判定用） */
static int g_last_tap_x, g_last_tap_y;

/* ============================================================ */
/* 页源解码回调（注入 logic 层的 mr_book 契约；可在后台线程调用） */
/* ============================================================ */
static meow_img *reader_load_page(const char *path, void *ud, int maxdim)
{
    (void)ud;
    meow_img *im = meow_img_load_file(path);
    if (!im) return NULL;
    meow_img *small = meow_img_downscale(im, maxdim);   /* 大图先缩再驻留 */
    if (small) { meow_img_free(im); im = small; }
    return im;
}

static void reader_unload_page(meow_img *img)
{
    meow_img_free(img);
}

/* ============================================================ */
/* 内存观测（验收用：进出 reader 对比）                          */
/* ============================================================ */
static long mem_kb(const char *path, const char *key)
{
    FILE *f = fopen(path, "r");
    if (!f) return -1;
    char line[128];
    long v = -1;
    size_t kl = strlen(key);
    while (fgets(line, sizeof line, f)) {
        if (strncmp(line, key, kl) == 0) { v = strtol(line + kl, NULL, 10); break; }
    }
    fclose(f);
    return v;
}

static int resident_pages(void)
{
    int n = 0;
    for (int i = 0; i < MR_WIN; i++)
        if (g_slot[i].img) n++;
    return n;
}

static long resident_bytes(void)
{
    long b = 0;
    for (int i = 0; i < MR_WIN; i++)
        if (g_slot[i].img) b += (long)g_slot[i].src_w * g_slot[i].src_h * 4;
    return b;
}

static void log_mem(const char *tag)
{
    meow_log(MEOW_LOG_INFO, "reader mem[%s]: avail=%ldKB rss=%ldKB pages=%d img=%ldKB",
             tag, mem_kb("/proc/meminfo", "MemAvailable:"),
             mem_kb("/proc/self/status", "VmRSS:"), resident_pages(), resident_bytes() / 1024);
}

/* ============================================================ */
/* 页图缓存                                                      */
/* ============================================================ */
static page_slot *slot_find(int idx)
{
    if (idx < 0) return NULL;
    for (int i = 0; i < MR_WIN; i++)
        if (g_slot[i].idx == idx && g_slot[i].img) return &g_slot[i];
    return NULL;
}

static void slot_clear(int i)
{
    if (i < 0 || i >= MR_WIN) return;
    if (g_slot[i].img) meow_img_free(g_slot[i].img);
    g_slot[i].img = NULL;
    g_slot[i].idx = -1;
    g_slot[i].src_w = g_slot[i].src_h = 0;
}

static void slots_free_all(void)
{
    for (int i = 0; i < MR_WIN; i++) slot_clear(i);
}

/* 放进缓存；缓存满时淘汰离当前页最远的一张。返回 1=已放入。 */
static int slot_put(int idx, meow_img *img)
{
    if (!img || idx < 0) return 0;
    int empty = -1, far = -1, far_d = -1;
    for (int i = 0; i < MR_WIN; i++) {
        if (g_slot[i].idx == idx && g_slot[i].img) { meow_img_free(img); return 0; }
        if (!g_slot[i].img && empty < 0) empty = i;
        int d = !g_slot[i].img ? -1 : abs(g_slot[i].idx - g_page);
        if (d > far_d) { far_d = d; far = i; }
    }
    int i = empty >= 0 ? empty : far;
    if (i < 0) { meow_img_free(img); return 0; }
    slot_clear(i);
    g_slot[i].idx = idx;
    g_slot[i].img = img;
    g_slot[i].src_w = meow_img_w(img);
    g_slot[i].src_h = meow_img_h(img);
    return 1;
}

/* 当前窗口：正常=当前±1；放大时只驻留当前页（给缩放临时缓冲让内存）。 */
static int in_window(int idx)
{
    if (g_count <= 0 || idx < 0 || idx >= g_count) return 0;
    if (g_zoom_pct > 100) return idx == g_page;
    return idx >= g_page - 1 && idx <= g_page + 1;
}

/* ============================================================ */
/* 后台解码                                                      */
/* ============================================================ */
static int req_queued(int idx)
{
    for (int i = 0; i < g_req_n; i++) {
        int p = (g_req_head + i) % MR_REQ_MAX;
        if (g_req[p].idx == idx) return 1;
    }
    return 0;
}

static void queue_page(int idx)
{
    if (!mr_book_valid(&g_book) || idx < 0 || idx >= g_count) return;
    if (slot_find(idx)) return;
    pthread_mutex_lock(&g_lock);
    if (!g_stop && !req_queued(idx) && g_req_n < MR_REQ_MAX) {
        g_req[g_req_tail].idx = idx;
        g_req[g_req_tail].gen = g_gen;
        g_req_tail = (g_req_tail + 1) % MR_REQ_MAX;
        g_req_n++;
        pthread_cond_signal(&g_cv);
    }
    pthread_mutex_unlock(&g_lock);
}

static void *reader_worker(void *arg)
{
    (void)arg;
    for (;;) {
        page_req req;
        pthread_mutex_lock(&g_lock);
        while (!g_stop && g_req_n == 0) pthread_cond_wait(&g_cv, &g_lock);
        if (g_stop) { pthread_mutex_unlock(&g_lock); break; }
        req = g_req[g_req_head];
        g_req_head = (g_req_head + 1) % MR_REQ_MAX;
        g_req_n--;
        pthread_mutex_unlock(&g_lock);

        uint64_t t0 = meow_ui_time_ms();
        meow_img *img = mr_book_open(&g_book, req.idx);
        uint64_t dt = meow_ui_time_ms() - t0;
        int w = img ? meow_img_w(img) : 0;
        int h = img ? meow_img_h(img) : 0;
        meow_log(MEOW_LOG_INFO, "reader decode page=%d ms=%llu %dx%d %s",
                 req.idx, (unsigned long long)dt, w, h, img ? "ok" : "fail");

        pthread_mutex_lock(&g_lock);
        if (img && !g_stop && g_res_n < MR_RES_MAX) {
            g_res[g_res_n].idx = req.idx;
            g_res[g_res_n].gen = req.gen;
            g_res[g_res_n].img = img;
            g_res_n++;
            img = NULL;
        }
        pthread_mutex_unlock(&g_lock);
        if (img) meow_img_free(img);
    }
    return NULL;
}

static void worker_start(void)
{
    if (g_worker_on) return;
    g_stop = 0;
    if (pthread_create(&g_worker, NULL, reader_worker, NULL) == 0) g_worker_on = 1;
}

static void worker_stop(void)
{
    if (!g_worker_on) return;
    pthread_mutex_lock(&g_lock);
    g_stop = 1;
    pthread_cond_broadcast(&g_cv);
    pthread_mutex_unlock(&g_lock);
    pthread_join(g_worker, NULL);
    g_worker_on = 0;

    pthread_mutex_lock(&g_lock);
    for (int i = 0; i < g_res_n; i++) meow_img_free(g_res[i].img);
    g_res_n = 0;
    g_req_n = 0;
    g_req_head = g_req_tail = 0;
    pthread_mutex_unlock(&g_lock);
}

/* 丢弃窗口外的排队请求（主线程调用）。 */
static void queue_prune(void)
{
    pthread_mutex_lock(&g_lock);
    page_req keep[MR_REQ_MAX];
    int n = 0;
    for (int i = 0; i < g_req_n; i++) {
        page_req r = g_req[(g_req_head + i) % MR_REQ_MAX];
        if (r.gen == g_gen && in_window(r.idx)) keep[n++] = r;
    }
    for (int i = 0; i < n; i++) g_req[i] = keep[i];
    g_req_head = 0;
    g_req_tail = n;
    g_req_n = n;
    pthread_mutex_unlock(&g_lock);
}

/* 收取后台结果：只留窗口内新页。返回 1=有图落位。 */
static int results_drain(void)
{
    page_res got[MR_RES_MAX];
    int n;
    pthread_mutex_lock(&g_lock);
    n = g_res_n;
    for (int i = 0; i < n; i++) got[i] = g_res[i];
    g_res_n = 0;
    pthread_mutex_unlock(&g_lock);

    int changed = 0;
    for (int i = 0; i < n; i++) {
        if (got[i].gen == g_gen && in_window(got[i].idx) && !slot_find(got[i].idx)) {
            if (slot_put(got[i].idx, got[i].img)) changed = 1;
        } else {
            meow_img_free(got[i].img);
        }
    }
    return changed;
}

/* 窗口随当前页移动：淘汰窗口外图 → 清掉窗口外请求 → 补齐缺失页（当前页优先）。 */
static void window_update(void)
{
    for (int i = 0; i < MR_WIN; i++)
        if (g_slot[i].idx >= 0 && !in_window(g_slot[i].idx)) slot_clear(i);
    queue_prune();

    queue_page(g_page);
    if (g_page - 1 >= 0) queue_page(g_page - 1);
    if (g_page + 1 < g_count) queue_page(g_page + 1);
}

/* ============================================================ */
/* 布局/绘制                                                     */
/* ============================================================ */
static void page_target_size(const page_slot *s, int *w, int *h)
{
    *w = *h = 0;
    if (!s) return;
    if (mr_nav_fit_size(g_fit, s->src_w, s->src_h, g_vw, g_vh, w, h) != 0) return;
    if (g_zoom_pct != 100) mr_nav_zoom_size(*w, *h, g_zoom_pct, w, h);
}

static void current_geom(int *w, int *h)
{
    page_slot *s = slot_find(g_page);
    if (s) { page_target_size(s, w, h); return; }
    /* 页未就绪：用 meta 估算，保证平移/缩放的夹取稳定。 */
    int sw = 0, sh = 0;
    if (mr_book_meta(&g_book, g_page, &sw, &sh) && sw > 0 && sh > 0) {
        mr_nav_fit_size(g_fit, sw, sh, g_vw, g_vh, w, h);
        if (g_zoom_pct != 100) mr_nav_zoom_size(*w, *h, g_zoom_pct, w, h);
        return;
    }
    *w = g_vw;
    *h = g_vh;
}

static void clamp_pan(void)
{
    int w, h;
    current_geom(&w, &h);
    mr_nav_pan_clamp(w, h, g_vw, g_vh, &g_pan_x, &g_pan_y);
}

/* 内容是否超出视口（原始档的方图/宽图即使不放大也需要平移）。 */
static int content_overflow(void)
{
    int w, h;
    current_geom(&w, &h);
    return w > g_vw || h > g_vh;
}

/* 平移模式：放大，或原始档溢出。此时单指拖动=平移，左右 tap=平移步进。 */
static int pan_mode(void)
{
    return g_zoom_pct > 100 || content_overflow();
}

/* 画一页（带水平位移）；图与目标尺寸相等时走原生 blit（翻页热路径），否则最近邻缩放。 */
static void draw_page_at(int idx, int off_x, int off_y)
{
    page_slot *s = slot_find(idx);
    if (!s) return;
    int w, h;
    page_target_size(s, &w, &h);
    if (w <= 0 || h <= 0) return;
    int x = (g_vw - w) / 2 + g_pan_x + off_x;
    int y = (g_vh - h) / 2 + g_pan_y + off_y;
    if (w == s->src_w && h == s->src_h) meow_ui_img(x, y, s->img);
    else meow_ui_img_scaled(x, y, w, h, s->img);
}

static void reader_draw(meow_view *v, const meow_theme *th, void *ctx)
{
    (void)v; (void)ctx;
    int w = g_vw, h = g_vh;

    if (g_open_err) {
        meow_ui_text_center(w / 2, h / 2 - 20, "无法打开目录", th->font_title, th->onSurface);
        meow_ui_text_center(w / 2, h / 2 + 24, g_dir, th->font_body, th->onSurfaceVariant);
        return;
    }
    if (g_count <= 0) {
        meow_ui_text_center(w / 2, h / 2 - 20, "空册", th->font_title, th->onSurface);
        meow_ui_text_center(w / 2, h / 2 + 24, "这个文件夹里没有图片", th->font_body,
                            th->onSurfaceVariant);
        return;
    }

    if (g_slide_delta != 0) {
        /* 动画帧：进场页从 from 滑到 0，当前页同步让位（只 blit 两张已缓存页图）。 */
        draw_page_at(g_page, g_anim_v - g_slide_from, 0);
        draw_page_at(g_page + g_slide_delta, g_anim_v, 0);
        return;
    }

    if (g_drag_mode == 1 && g_drag_off != 0) {
        /* 跟手：当前页按位移走，相邻页在另一侧同时露出（未就绪就只画当前页）。 */
        int rtl = mr_reader_get_direction() == MR_DIR_RTL;
        int delta = mr_nav_swipe_delta(rtl, g_drag_off);
        int target = mr_nav_clamp_page(g_page + delta, g_count);
        if (target != g_page && slot_find(target)) {
            int from = mr_nav_slide_from(rtl, delta, g_vw);
            draw_page_at(target, g_drag_off + from, 0);
        }
        draw_page_at(g_page, g_drag_off, 0);
        return;
    }

    draw_page_at(g_page, 0, 0);
    if (!slot_find(g_page)) {
        meow_ui_text_center(w / 2, h / 2, "加载中…", th->font_body, th->onSurfaceVariant);
    }
}

/* ============================================================ */
/* 状态动作                                                      */
/* ============================================================ */
static void update_title(void)
{
    if (!g_tb) return;
    static const char *const fit_name[MR_FIT_COUNT] = { "适宽", "适高", "原始" };
    const char *fit = (g_fit >= 0 && g_fit < MR_FIT_COUNT) ? fit_name[g_fit] : "适宽";
    char buf[64];
    if (g_count > 0) snprintf(buf, sizeof buf, "%d / %d  %s", g_page + 1, g_count, fit);
    else snprintf(buf, sizeof buf, "0 / 0");
    meow_topappbar_set_title(g_tb, buf);
}

static void set_fit(int fit)
{
    g_fit = (fit < 0 || fit >= MR_FIT_COUNT) ? MR_FIT_WIDTH : fit;
    g_zoom_pct = 100;
    g_pan_x = g_pan_y = 0;
    update_title();
    meow_ui_invalidate(0, 0, g_vw, g_vh);
}

static void set_chrome(int on)
{
    on = on ? 1 : 0;
    if (g_chrome == on) return;
    g_chrome = on;
    if (g_tb) meow_widget_set_rect(g_tb, 0, on ? 0 : -MR_TOPBAR_H, g_vw, MR_TOPBAR_H);
    meow_ui_invalidate(0, 0, g_vw, MR_TOPBAR_H);
}

/* 平移（dx>0 = 内容右移）；放大或原始档溢出时可用。 */
static void pan_by(int dx, int dy)
{
    if (!pan_mode()) return;
    g_pan_x += dx;
    g_pan_y += dy;
    clamp_pan();
    meow_ui_invalidate(0, 0, g_vw, g_vh);
}

static void commit_page(int target)
{
    target = mr_nav_clamp_page(target, g_count);
    if (target < 0) return;
    g_page = target;
    g_zoom_pct = 100;
    g_pan_x = g_pan_y = 0;
    window_update();
    update_title();
    meow_ui_invalidate(0, 0, g_vw, g_vh);
}

/* ---- 翻页滑动吸附 ---- */
static void slide_update(meow_anim *a, float value, void *ctx)
{
    (void)a; (void)ctx;
    g_anim_v = (int)value;
    meow_ui_invalidate(0, 0, g_vw, g_vh);
}

static void slide_done(meow_anim *a, int canceled, void *ctx)
{
    (void)a; (void)ctx;
    g_snap = NULL;
    if (g_quitting) return;
    int delta = g_slide_delta;
    g_slide_delta = 0;
    g_slide_from = 0;
    g_anim_v = 0;
    if (!canceled && delta)
        commit_page(g_page + delta);
    else
        meow_ui_invalidate(0, 0, g_vw, g_vh);
    meow_log(MEOW_LOG_INFO, "reader flip done page=%d/%d total_ms=%llu",
             g_page + 1, g_count,
             (unsigned long long)(meow_ui_time_ms() - g_flip_t0));
}

/* 从 start_off（松手时的位移，无跟手时为 0）滑到目标页。1=动画已启动。 */
static int start_slide(int delta, int start_off)
{
    if (g_snap || g_bounce) return 0;
    int rtl = mr_reader_get_direction() == MR_DIR_RTL;
    g_slide_delta = delta;
    g_slide_from = mr_nav_slide_from(rtl, delta, g_vw);
    g_anim_v = start_off + g_slide_from;
    meow_anim_desc d = {
        (float)g_anim_v, 0.0f, MR_SLIDE_MS, MEOW_EASE_OUT,
        slide_update, slide_done, NULL,
    };
    uint64_t t0 = meow_ui_time_ms();
    g_snap = meow_anim_start(&d);                  /* start 即回调 update：首帧在这里绘制 */
    uint64_t dt = meow_ui_time_ms() - t0;
    if (!g_snap) {
        g_slide_delta = 0;
        g_slide_from = 0;
        g_anim_v = 0;
        commit_page(g_page + delta);
        return 0;
    }
    meow_log(MEOW_LOG_INFO, "reader slide first_frame_ms=%llu page=%d->%d",
             (unsigned long long)dt, g_page + 1, g_page + delta + 1);
    return 1;
}

/* ---- 未过阈值回弹 ---- */
static void bounce_update(meow_anim *a, float value, void *ctx)
{
    (void)a; (void)ctx;
    g_drag_off = (int)value;
    meow_ui_invalidate(0, 0, g_vw, g_vh);
}

static void bounce_done(meow_anim *a, int canceled, void *ctx)
{
    (void)a; (void)canceled; (void)ctx;
    g_bounce = NULL;
    g_drag_off = 0;
    g_drag_mode = 0;
    if (!g_quitting) meow_ui_invalidate(0, 0, g_vw, g_vh);
}

static void start_bounce(int from_off)
{
    if (g_bounce || g_snap) { g_drag_off = 0; g_drag_mode = 0; return; }
    meow_anim_desc d = {
        (float)from_off, 0.0f, MR_BOUNCE_MS, MEOW_EASE_OUT,
        bounce_update, bounce_done, NULL,
    };
    g_bounce = meow_anim_start(&d);
    if (!g_bounce) { g_drag_off = 0; g_drag_mode = 0; meow_ui_invalidate(0, 0, g_vw, g_vh); }
}

/* 点击触发的翻页（无跟手位移）。 */
static void page_flip(int delta)
{
    if (delta == 0 || g_count <= 0) return;
    int target = mr_nav_clamp_page(g_page + delta, g_count);
    if (target == g_page) return;                  /* 首/末页不动 */
    if (g_snap || g_bounce) return;                /* 短动画中忽略连点 */
    if (g_zoom_pct != 100) {                       /* 翻页回到基准缩放 */
        g_zoom_pct = 100;
        g_pan_x = g_pan_y = 0;
    }
    results_drain();

    g_flip_t0 = meow_ui_time_ms();
    if (slot_find(target)) {
        if (start_slide(delta, 0))
            meow_log(MEOW_LOG_INFO, "reader flip %d->%d hit", g_page + 1, target + 1);
        else
            meow_log(MEOW_LOG_INFO, "reader flip %d->%d hit (no anim slot)", g_page + 1, target + 1);
    } else {
        meow_log(MEOW_LOG_INFO, "reader flip %d->%d miss (decode pending)", g_page + 1, target + 1);
        commit_page(target);
    }
}

/* ============================================================ */
/* 跟手拖动                                                      */
/* ============================================================ */
static void drag_paint(void)
{
    uint64_t now = meow_ui_time_ms();
    int gap = g_zoom_pct > 100 ? 33 : MR_PAINT_MS;   /* 缩放帧要重采样：30fps 上限 */
    if (now - g_last_paint < (uint64_t)gap) return;
    g_last_paint = now;
    meow_ui_invalidate(0, 0, g_vw, g_vh);
}

/* 松手：过阈值且目标页已缓存 → 从当前位移吸附过去；否则回弹。 */
static void drag_finish(void)
{
    if (!g_dragging) return;
    g_dragging = 0;
    int dx = g_drag_off;
    int mode = g_drag_mode;
    g_drag_off = 0;
    g_drag_mode = 0;

    if (mode != 1 || abs(dx) < MR_DRAG_SLOP) {
        meow_ui_invalidate(0, 0, g_vw, g_vh);
        return;
    }
    int rtl = mr_reader_get_direction() == MR_DIR_RTL;
    int delta = mr_nav_swipe_delta(rtl, dx);
    int target = mr_nav_clamp_page(g_page + delta, g_count);
    if (target != g_page && mr_nav_commit(dx, g_vw)) {
        g_flip_t0 = meow_ui_time_ms();
        if (slot_find(target) && start_slide(delta, dx)) {
            meow_log(MEOW_LOG_INFO, "reader drag flip %d->%d hit", g_page + 1, target + 1);
        } else {
            meow_log(MEOW_LOG_INFO, "reader drag flip %d->%d miss (decode pending)",
                     g_page + 1, target + 1);
            commit_page(target);
        }
    } else {
        g_drag_off = dx;                 /* start_bounce 从这里起 */
        g_drag_mode = 1;
        start_bounce(dx);
    }
}

void reader_on_touch_down(int x, int y)
{
    if (!g_ctrl.active || g_quitting) return;
    if (g_count <= 0) return;
    if (y >= g_vh - 28) return;                   /* 屏底热区：系统回桌面，勿劫持 */
    if (x < 24) return;                           /* 左缘：系统返回手势，勿劫持 */
    if (g_chrome && y < MR_TOPBAR_H) return;      /* chrome 上的点击交给 tap */
    if (g_snap || g_bounce) return;               /* 短动画中不接新手势 */

    g_dragging = 1;
    g_drag_mode = pan_mode() ? 2 : 1;
    g_drag_x0 = x;
    g_drag_y0 = y;
    g_drag_off = 0;
    g_drag_pan_x0 = g_pan_x;
    g_drag_pan_y0 = g_pan_y;
    g_touch_moved = 0;
}

void reader_on_touch_move(int x, int y)
{
    if (!g_ctrl.active || !g_dragging || g_quitting) return;
    int dx = x - g_drag_x0;
    int dy = y - g_drag_y0;
    int adx = abs(dx), ady = abs(dy);
    if (!g_touch_moved && (adx >= MR_DRAG_SLOP || ady >= MR_DRAG_SLOP)) {
        g_touch_moved = 1;
        g_tap_pending = 0;                        /* 变成拖动：作废未决单击 */
        g_last_tap_ms = 0;
    }

    if (g_drag_mode == 2) {                       /* 放大态：单指拖拽平移 */
        g_pan_x = g_drag_pan_x0 + dx;
        g_pan_y = g_drag_pan_y0 + dy;
        clamp_pan();
        drag_paint();
        return;
    }

    /* 竖向主导 → 放弃横滑翻页（松手后不算点击，见 reader_on_tap）。 */
    if (ady > adx * 3 / 2 && ady > 16) {
        g_dragging = 0;
        g_drag_mode = 0;
        g_drag_off = 0;
        meow_ui_invalidate(0, 0, g_vw, g_vh);
        return;
    }

    int rtl = mr_reader_get_direction() == MR_DIR_RTL;
    int delta = mr_nav_swipe_delta(rtl, dx);
    int target = mr_nav_clamp_page(g_page + delta, g_count);
    int off = dx;
    if (target == g_page) {                       /* 首/末页：橡皮筋 */
        int lim = g_vw / 4;
        if (off > lim) off = lim;
        if (off < -lim) off = -lim;
    }
    g_drag_off = off;
    drag_paint();
}

/* ============================================================ */
/* 单击 / 双击                                                   */
/* ============================================================ */
static void tap_topbar(int x, int y)
{
    if (!g_tb) return;
    int hit = meow_topappbar_hit(g_tb, x, y);
    if (hit == MEOW_TOPBAR_BACK) {
        meow_view_page_pop();
        return;
    }
    if (hit >= 0) set_fit(mr_nav_fit_next(g_fit));
}

static void tap_content(int x, int y)
{
    (void)y;
    if (g_count <= 0) return;
    int zone = mr_nav_tap_zone(x, g_vw);
    if (zone == MR_ZONE_MIDDLE) {
        set_chrome(!g_chrome);
        return;
    }
    if (pan_mode()) {
        /* 平移模式：左右分区改为平移步进（配合拖拽，补齐两个方向）。 */
        pan_by(zone == MR_ZONE_LEFT ? g_vw / 3 : -g_vw / 3, 0);
        return;
    }
    page_flip(mr_nav_tap_delta(mr_reader_get_direction() == MR_DIR_RTL, zone));
}

static void tap_double(int x, int y)
{
    if (g_count <= 0) return;
    if (g_zoom_pct > 100) {
        g_zoom_pct = 100;
        g_pan_x = g_pan_y = 0;
    } else {
        /* 以双击点为锚放大：该点保持在手指下（再夹到可平移范围）。
         * 倍率按内存纪律夹取：缩放临时缓冲 = 目标宽×高×4，超过软上限就降档。 */
        int bw = 0, bh = 0;
        current_geom(&bw, &bh);
        int z = MR_ZOOM_PCT;
        while (z > 100 && (long long)bw * bh * 4 * z * z / 10000 > MR_ZOOM_TEMP_CAP) z -= 25;
        g_zoom_pct = z;
        g_pan_x = (g_vw / 2 - x) * (z - 100) / 100;
        g_pan_y = (g_vh / 2 - y) * (z - 100) / 100;
        clamp_pan();
    }
    window_update();
    meow_ui_invalidate(0, 0, g_vw, g_vh);
}

static void tap_flush(void)
{
    if (!g_tap_pending) return;
    g_tap_pending = 0;
    int x = g_tap_x, y = g_tap_y;
    if (g_chrome && y >= 0 && y < MR_TOPBAR_H) tap_topbar(x, y);
    else tap_content(x, y);
}

void reader_on_tap(int x, int y)
{
    if (!g_ctrl.active || g_quitting) return;

    /* 跟手手势收尾：移动过就按拖动处理（过阈值翻页 / 否则回弹），不再当点击。 */
    if (g_dragging) {
        if (g_touch_moved) {
            drag_finish();
            g_touch_moved = 0;
            return;
        }
        g_dragging = 0;
        g_drag_mode = 0;
        g_drag_off = 0;
    } else if (g_touch_moved) {
        g_touch_moved = 0;                        /* 竖向拖动被 SDK 报成 TAP：忽略 */
        return;
    }
    g_touch_moved = 0;

    /* chrome 上的点击即时生效，不参与双击判定。 */
    if (g_chrome && y >= 0 && y < MR_TOPBAR_H) {
        g_tap_pending = 0;
        g_last_tap_ms = 0;
        tap_topbar(x, y);
        return;
    }

    uint64_t now = meow_ui_time_ms();
    if (g_last_tap_ms && now - g_last_tap_ms <= MR_DOUBLE_MS &&
        abs(x - g_last_tap_x) <= 48 && abs(y - g_last_tap_y) <= 48) {
        g_tap_pending = 0;                        /* 取消第一击的单击动作 */
        g_last_tap_ms = 0;
        tap_double(x, y);
        return;
    }
    tap_flush();                                  /* 上一击已过期：先执行 */
    g_tap_pending = 1;
    g_tap_x = x;
    g_tap_y = y;
    g_tap_ms = now;
    g_last_tap_ms = now;
    g_last_tap_x = x;
    g_last_tap_y = y;
    if (!g_ticker) tap_flush();                   /* 无节拍器兜底：不延迟单击 */
}

/* ============================================================ */
/* 节拍：收结果 + 单击超时                                       */
/* ============================================================ */
static void reader_tick(void)
{
    if (!g_ctrl.active || g_quitting) return;
    uint64_t now = meow_ui_time_ms();
    if (now - g_last_tick < MR_TICK_MS) return;
    g_last_tick = now;

    int had_current = slot_find(g_page) != NULL;
    if (results_drain() && !had_current && slot_find(g_page) && !g_dragging)
        meow_ui_invalidate(0, 0, g_vw, g_vh);

    if (g_tap_pending && now - g_tap_ms >= MR_DOUBLE_MS) tap_flush();
}

static void ticker_update(meow_anim *a, float value, void *ctx)
{
    (void)a; (void)value; (void)ctx;
    reader_tick();
}

static void ticker_done(meow_anim *a, int canceled, void *ctx)
{
    (void)a; (void)ctx;
    g_ticker = NULL;
    if (canceled || g_quitting || !g_ctrl.active) return;
    meow_anim_desc d = { 0.0f, 1.0f, 0xFFFFFFFFu, MEOW_EASE_LINEAR,
                         ticker_update, ticker_done, NULL };
    g_ticker = meow_anim_start(&d);
}

static void ticker_start(void)
{
    if (g_ticker) return;
    meow_anim_desc d = { 0.0f, 1.0f, 0xFFFFFFFFu, MEOW_EASE_LINEAR,
                         ticker_update, ticker_done, NULL };
    g_ticker = meow_anim_start(&d);
    if (!g_ticker) meow_log(MEOW_LOG_WARN, "reader ticker unavailable (anim pool full)");
}

/* ============================================================ */
/* 输入：滑动手势（view on_event，先于 app.c 的 on_swipe）        */
/* ============================================================ */
static int reader_event(meow_view *v, int ev, int a, int b, void *ctx)
{
    (void)v; (void)ctx;
    if (!g_ctrl.active || g_quitting) return 0;
    if (ev != MR_EV_SWIPE) return 0;

    if (a == MEOW_SWIPE_LEFT) {                   /* 左缘返回：交给 app.c page_pop */
        g_dragging = 0;
        g_drag_mode = 0;
        g_drag_off = 0;
        g_touch_moved = 0;
        return 0;
    }
    if (a == MEOW_SWIPE_RIGHT) {
        if (g_dragging) { drag_finish(); return 1; }
        if (g_count <= 0) return 1;
        if (pan_mode()) { pan_by(b, 0); return 1; }
        page_flip(mr_nav_swipe_delta(mr_reader_get_direction() == MR_DIR_RTL, b));
        return 1;
    }
    if (a == MEOW_SWIPE_UP || a == MEOW_SWIPE_DOWN) {
        if (g_dragging) { drag_finish(); return 1; }
        if (pan_mode()) {                         /* 放大 / 原始档溢出：纵向滑动平移 */
            pan_by(0, a == MEOW_SWIPE_DOWN ? b : -b);
            return 1;
        }
        return 0;                                 /* 未放大：纵向滑动不归本页 */
    }
    return 0;
}

/* ============================================================ */
/* view 生命周期                                                 */
/* ============================================================ */
static void reader_state_reset(void)
{
    slots_free_all();                           /* 静态槽位初值是 idx=0/img=NULL，先清空 */
    g_count = 0;
    g_open_err = 0;
    g_page = 0;
    g_fit = MR_FIT_WIDTH;
    g_zoom_pct = 100;
    g_pan_x = g_pan_y = 0;
    g_chrome = 1;
    g_slide_delta = 0;
    g_slide_from = 0;
    g_anim_v = 0;
    g_dragging = 0;
    g_drag_mode = 0;
    g_drag_off = 0;
    g_touch_moved = 0;
    g_tap_pending = 0;
    g_last_tap_ms = 0;
    g_quitting = 0;
}

static void reader_page_enter(meow_view *v, void *ctx)
{
    mr_page_ctrl *c = (mr_page_ctrl *)ctx;
    c->active = 1;
    g_quitting = 0;

    g_vw = meow_ui_width();
    g_vh = meow_ui_height();
    v->x = 0;
    v->y = 0;
    v->w = g_vw;
    v->h = g_vh;

    meow_ui_set_fullscreen(1);
    const meow_theme *th = meow_theme_get();
    meow_ui_set_page_bg(th->surface);

    reader_state_reset();
    g_gen++;                                   /* 作废旧册的异步结果 */
    g_last_tick = 0;
    g_last_paint = 0;

    /* 非根页：控件在 on_enter 建 → owner=ACT_READER（§6.1 跨页泄漏防线）。 */
    if (!g_tb) g_tb = meow_topappbar_create(0, 0, g_vw, MR_TOPBAR_H, "");
    if (g_tb) {
        meow_topappbar_set_back(g_tb, 1);
        int ai = meow_topappbar_add_action(g_tb, "");
        if (ai >= 0) meow_topappbar_set_item_icon(g_tb, ai, MEOW_ICON_REFRESH);
        meow_widget_set_rect(g_tb, 0, 0, g_vw, MR_TOPBAR_H);
    }

    /* 页源：目录册（文件夹即书）。maxdim 取屏幕长边，页图驻留 ≈ 屏宽×屏高×4。 */
    int maxdim = g_vw > g_vh ? g_vw : g_vh;
    int n = mr_dir_book_init(&g_db, g_dir, maxdim,
                             reader_load_page, reader_unload_page, NULL);
    if (n < 0) {
        g_open_err = 1;
        meow_log(MEOW_LOG_WARN, "reader open failed: %s", g_dir);
    } else {
        g_count = n;
    }
    mr_dir_book_bind(&g_book, g_count > 0 ? &g_db : NULL);

    worker_start();
    if (!g_worker_on && g_count > 0) {
        /* 线程创建失败：退化为主线程同步解第一页（保证不是纯白屏）。 */
        meow_img *first = mr_book_open(&g_book, 0);
        if (first) slot_put(0, first);
        meow_log(MEOW_LOG_WARN, "reader worker unavailable, sync first page");
    }
    window_update();                           /* 当前页优先进队 */
    ticker_start();
    update_title();

    meow_log(MEOW_LOG_INFO, "reader enter dir=%s pages=%d fit=%d", g_dir, g_count, g_fit);
    log_mem("enter");
    mr_nav_report();
    meow_ui_paint_full();

    /* 首页解码是异步的：先给一帧文字/页码，结果在 tick 里落位。 */
    reader_tick();
}

static void reader_page_leave(meow_view *v, void *ctx)
{
    (void)v;
    ((mr_page_ctrl *)ctx)->active = 0;
    g_quitting = 1;

    if (g_snap) { meow_anim_cancel(g_snap); g_snap = NULL; }
    if (g_bounce) { meow_anim_cancel(g_bounce); g_bounce = NULL; }
    if (g_ticker) { meow_anim_cancel(g_ticker); g_ticker = NULL; }

    worker_stop();                             /* 先停线程，再释放册/图 */
    slots_free_all();
    mr_book_destroy(&g_book);
    mr_dir_book_free(&g_db);

    if (g_tb) { meow_widget_free(g_tb); g_tb = NULL; }

    g_dragging = 0;
    g_drag_mode = 0;
    g_drag_off = 0;
    g_tap_pending = 0;
    g_slide_delta = 0;
    g_slide_from = 0;
    g_anim_v = 0;

    log_mem("leave");
    meow_ui_set_fullscreen(0);
}

meow_view *reader_view_create(void)
{
    static const meow_view_hooks h = {
        .on_enter = reader_page_enter,
        .on_leave = reader_page_leave,
        .on_draw  = reader_draw,
        .on_event = reader_event,
    };
    return meow_view_create(ACT_READER, MEOW_VIEW_ACTIVITY, &h, &g_ctrl);
}

/* ============================================================ */
/* 书库 → 阅读器导航（app.c / library.c 既有接缝）               */
/* ============================================================ */
const char *mr_reader_dir(void)
{
    return g_dir;
}

void mr_reader_open_dir(const char *path)
{
    if (!path) return;
    snprintf(g_dir, sizeof g_dir, "%s", path);
    meow_log(MEOW_LOG_INFO, "reader open: %s", g_dir);
    meow_view_page_push(ACT_READER);
}