/* play/mem_watch.c — 边播边监控**取证**实现（接口见 mem_watch.h；agent 32bit 大文件 OOM 取证）。
 *
 * 归属演进（2026-09-02 定案，ARCHITECTURE_PRINCIPLES ③混合）：**降载决策上收通用层**——
 *   A（DONTNEED 治理）+ C（/proc/meminfo Cached 监控）分别归 SDK meow_cachegov / meow_svc_perf；
 *   本模块退化为「RssAnon 取证」：低频读 /proc/self/status（优先 RssAnon，缺失回退 VmRSS），
 *   记录匿名内存峰值，**仅供日志**。不再驱动下载/预取降载（那由 meow_cachegov_download_paused
 *   / prefetch_paused 查询）。**绝不打断解码/播放**。
 *
 * 阈值滞后（仅用于取证 level 标注）：
 *   kb >= CRITICAL → level=2；kb >= HIGH 且当前<2 → level=1；kb <= LOW → level=0；其它保持。
 * 本模块自含：只依赖 pthread + meow_log（SDK 日志），不依赖 core/app 其它 TU。
 */
#include "mem_watch.h"
#include "../sdk/include/meow_ui_log.h"

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

/* 默认阈值（设备缺省；宿主单测用 env/force 桩覆盖） */
#define MEM_WATCH_PERIOD_MS      500
#define MEM_WATCH_HIGH_KB        (30 * 1024)
#define MEM_WATCH_LOW_KB         (20 * 1024)
#define MEM_WATCH_CRITICAL_KB    (40 * 1024)

struct mw_cfg {
    int   period_ms;
    long  high_kb;
    long  low_kb;
    long  critical_kb;
};

static struct mw_cfg g_cfg = {
    .period_ms   = MEM_WATCH_PERIOD_MS,
    .high_kb     = MEM_WATCH_HIGH_KB,
    .low_kb      = MEM_WATCH_LOW_KB,
    .critical_kb = MEM_WATCH_CRITICAL_KB,
};

static pthread_mutex_t g_mu        = PTHREAD_MUTEX_INITIALIZER;
static pthread_t       g_thr;
static int             g_thr_on;
static volatile int    g_quit;
static long            g_rss_anon_kb;   /* 最近一次采样（KB；-1=不可读） */
static long            g_peak_song_kb;  /* 本曲匿名峰值（song_begin 清零） */
static int             g_level;         /* NCM_MEM_LVL_*（仅取证日志） */
static long            g_forced_kb = -1;  /* 宿主桩 ≥0 时替代真读 */

/* env 覆盖阈值：非法值回落默认。 */
static int env_int(const char *k, int def)
{
    const char *e = getenv(k);
    if (!e || !e[0]) return def;
    int v = atoi(e);
    return v > 0 ? v : def;
}
static long env_long(const char *k, long def)
{
    const char *e = getenv(k);
    if (!e || !e[0]) return def;
    long v = atol(e);
    return v > 0 ? v : def;
}

/* 读匿名 RSS（KB）。优先 RssAnon；缺则回退 VmRSS；都无 → -1。 */
static long read_rss_kb(void)
{
    pthread_mutex_lock(&g_mu);
    long forced = g_forced_kb;
    pthread_mutex_unlock(&g_mu);
    if (forced >= 0) return forced;

    FILE *fp = fopen("/proc/self/status", "r");
    if (!fp) return -1;
    char line[256];
    long anon = -1, rss = -1;
    while (fgets(line, sizeof line, fp))
        if (!strncmp(line, "RssAnon:", 8)) anon = atol(line + 8);
        else if (rss < 0 && !strncmp(line, "VmRSS:", 6)) rss = atol(line + 6);
    fclose(fp);
    return anon >= 0 ? anon : rss;
}

static const char *level_str(int lvl)
{
    switch (lvl) {
        case NCM_MEM_LVL_HIGH:     return "high";
        case NCM_MEM_LVL_CRITICAL: return "critical";
        default:                   return "normal";
    }
}

static void *watch_thread(void *arg)
{
    (void)arg;
    while (!g_quit) {
        long kb = read_rss_kb();
        int lvl;
        pthread_mutex_lock(&g_mu);
        g_rss_anon_kb = kb;
        if (kb > g_peak_song_kb) g_peak_song_kb = kb;
        long hi = g_cfg.high_kb, lo = g_cfg.low_kb, cr = g_cfg.critical_kb;
        /* 滞后三档（仅取证 level 标注） */
        if (kb >= cr)                              lvl = NCM_MEM_LVL_CRITICAL;
        else if (kb >= hi)                         lvl = (g_level == NCM_MEM_LVL_CRITICAL) ? NCM_MEM_LVL_CRITICAL : NCM_MEM_LVL_HIGH;
        else if (kb <= lo)                         lvl = NCM_MEM_LVL_NORMAL;
        else                                       lvl = g_level;   /* 滞后带：保持 */
        if (lvl != g_level) {
            meow_log(MEOW_LOG_INFO,
                     "[mem] rss_anon=%ldKB peak=%ldKB level=%s (H=%ldK/L=%ldK/C=%ldK)",
                     kb, g_peak_song_kb, level_str(lvl), hi, lo, cr);
        }
        g_level = lvl;
        pthread_mutex_unlock(&g_mu);
        usleep((useconds_t)g_cfg.period_ms * 1000u);
    }
    return NULL;
}

int mem_watch_start(void)
{
    pthread_mutex_lock(&g_mu);
    if (g_thr_on) { pthread_mutex_unlock(&g_mu); return 0; }
    /* 开关（默认开；NCM_MEM_WATCH_ENABLED=0/off 关闭监控，行为退化为旧版零侵入） */
    const char *en = getenv("NCM_MEM_WATCH_ENABLED");
    if (en && (!en[0] || !strcmp(en, "0") || !strcmp(en, "off") || !strcmp(en, "false"))) {
        pthread_mutex_unlock(&g_mu);
        meow_log(MEOW_LOG_INFO, "[mem] watch disabled (NCM_MEM_WATCH_ENABLED=%s)", en);
        return 0;
    }
    /* 阈值 env 覆盖（宿主单测） */
    g_cfg.period_ms   = env_int("NCM_MEM_WATCH_PERIOD_MS", MEM_WATCH_PERIOD_MS);
    g_cfg.high_kb     = env_long("NCM_MEM_WATCH_HIGH_KB", MEM_WATCH_HIGH_KB);
    g_cfg.low_kb      = env_long("NCM_MEM_WATCH_LOW_KB", MEM_WATCH_LOW_KB);
    g_cfg.critical_kb = env_long("NCM_MEM_WATCH_CRITICAL_KB", MEM_WATCH_CRITICAL_KB);
    g_quit = 0;
    pthread_attr_t a;
    pthread_attr_init(&a);
    pthread_attr_setstacksize(&a, (size_t)(128 * 1024));   /* 同 ncm_thread_create 128KB（内存瘦身，OOM 修复） */
    int rc = pthread_create(&g_thr, &a, watch_thread, NULL);
    pthread_attr_destroy(&a);
    if (rc != 0) { pthread_mutex_unlock(&g_mu); return -1; }
    g_thr_on = 1;
    pthread_mutex_unlock(&g_mu);
    meow_log(MEOW_LOG_INFO,
             "[mem] watch started period=%dms H=%ldK L=%ldK C=%ldK (RssAnon 优先)",
             g_cfg.period_ms, g_cfg.high_kb, g_cfg.low_kb, g_cfg.critical_kb);
    return 0;
}

void mem_watch_stop(void)
{
    g_quit = 1;
    pthread_mutex_lock(&g_mu);
    if (g_thr_on) { g_thr_on = 0; pthread_detach(g_thr); }
    pthread_mutex_unlock(&g_mu);
}

int mem_watch_level(void)
{
    pthread_mutex_lock(&g_mu);
    int v = g_level;
    pthread_mutex_unlock(&g_mu);
    return v;
}

long mem_watch_rss_anon_kb(void)
{
    pthread_mutex_lock(&g_mu);
    long v = g_rss_anon_kb;
    pthread_mutex_unlock(&g_mu);
    return v;
}

void mem_watch_song_begin(void)
{
    long kb = read_rss_kb();          /* 起播即采样当前内存，本曲峰值从当前起算 */
    pthread_mutex_lock(&g_mu);
    g_peak_song_kb = kb;
    pthread_mutex_unlock(&g_mu);
    meow_log(MEOW_LOG_INFO, "[mem] song begin rss_anon=%ldKB", kb);
}

/* 播完/切歌释放钩子之后调用：落本曲峰值 + 重置计数。 */
void mem_watch_song_end(void)
{
    pthread_mutex_lock(&g_mu);
    long peak = g_peak_song_kb;
    g_peak_song_kb = g_rss_anon_kb;
    pthread_mutex_unlock(&g_mu);
    meow_log(MEOW_LOG_INFO, "[mem] song end peak_anon=%ldKB (released)", peak);
}

void mem_watch_set_forced_kb(long kb)
{
    pthread_mutex_lock(&g_mu);
    g_forced_kb = kb;
    pthread_mutex_unlock(&g_mu);
}