/* bench/cover_chain_sim.c — 封面链离线回归（0 真实请求，REPORT §18）。
 *
 * 驱动真实 app/logic/cover.c（worker 线程/ncm_cache LRU/cover_current.jpg 落盘），
 * HTTP 端点为本地合成 stub（按 URL 生成可区分内容，可注入失败次数模拟慢/坏网络），
 * meow_img 为假句柄（嵌内容哈希，不真解码 JPEG——测的是链路逻辑不是解码器）。
 *
 * 用例：
 *   T1 首次请求 → 封面出现（内容哈希对得上 URL）；
 *   T2 定居后 worker **不忙等**：cover_changed() 在 1.2s 内不得再置位
 *      （§18 前：成功后不清目标 → 每圈解码+换入+g_gen++ 死循环，CPU 占满且播放页每帧
 *       整盘重绘——本用例在旧代码上必 FAIL）；
 *   T3 切歌换 URL → 封面换入新内容 + cover_current.jpg 同步更新（launcher 媒体卡片读它）；
 *   T4 重复请求同一 URL → 去重（0 新增 HTTP，0 换入）；
 *   T5 网络失败 ×2 后退避重试成功（不无声死等）；
 *   T6 连续失败 ≥8 次放弃（目标清除，不永久占 worker）；
 *   T7 空/NULL URL 忽略；cover_cache_reset 清空。
 *
 * 编译（宿主，ncm_app 目录下；weak cover_put 兼容 §18 前的 cover.c 做对照）：
 *   gcc -O2 -ffunction-sections -DJSMN_HEADER -I. -I../sdk -I../meow_launcherd \
 *       -Icore -Ivendor/jsmn -c bench/cover_chain_sim.c -o /tmp/cs.o
 *   gcc -O2 -ffunction-sections -DJSMN_HEADER -I. -I../sdk -I../meow_launcherd \
 *       -Icore -Ivendor/jsmn -c app/logic/cover.c -o /tmp/cs_cover.o
 *   gcc -O2 -ffunction-sections -DJSMN_HEADER -Icore -c core/ncm_cache.c -o /tmp/cs_cache.o
 *   gcc -O2 -ffunction-sections -DJSMN_HEADER -Icore -c core/ncm_store.c -o /tmp/cs_store.o
 *   gcc -O2 -Wl,--gc-sections -o cover_chain_sim /tmp/cs.o /tmp/cs_cover.o /tmp/cs_cache.o \
 *       /tmp/cs_store.o -lpthread
 * 运行：./cover_chain_sim  （0 网络；PASS/FAIL 退出码）
 */
#include "../app/ncm_app_internal.h"
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <unistd.h>
#include <sys/stat.h>

ncm_app_state_t g_st;
volatile int    g_app_quit = 0;
int             g_host_mock = 0;

/* ---- 公共 stub ---- */
size_t ncm_strlcpy(char *dst, const char *src, size_t sz)
{
    size_t n = 0;
    if (sz) {
        while (src[n] && n < sz - 1) { dst[n] = src[n]; n++; }
        dst[n] = 0;
    }
    while (src[n]) n++;
    return n;
}

static int g_log_warns;
void meow_log(meow_log_level lvl, const char *fmt, ...)
{
    if (lvl >= MEOW_LOG_WARN) g_log_warns++;
    (void)fmt;
}

/* ---- 假 meow_img：嵌内容 FNV 哈希（链路验证用，不真解码） ---- */
struct meow_img { unsigned long hash; int len; int freed; };

static unsigned long fnv1a(const unsigned char *p, size_t n)
{
    unsigned long h = 1469598103934665603UL;
    for (size_t i = 0; i < n; i++) { h ^= p[i]; h *= 1099511628211UL; }
    return h;
}

meow_img *meow_img_load_mem(const void *buf, int len)
{
    if (!buf || len <= 0) return NULL;
    meow_img *im = (meow_img *)malloc(sizeof *im);
    if (!im) return NULL;
    im->hash = fnv1a((const unsigned char *)buf, (size_t)len);
    im->len = len;
    im->freed = 0;
    return im;
}

void meow_img_free(meow_img *im)
{
    if (!im) return;
    im->freed = 1;
    free(im);
}

/* §18 前的 cover.c 无 cover_put：weak 空实现让同一 sim 可对照旧代码（新代码强符号覆盖）。 */
__attribute__((weak)) void cover_put(void) { }

/* ---- HTTP stub：内容 = djb2(url) 填充 4KB（每 URL 唯一）；可注入失败/延迟 ---- */
static int   g_http_calls;
static int   g_fail_next;      /* 剩余注入失败次数 */
static int   g_delay_ms;       /* 模拟慢网络 */

static unsigned long djb2(const char *s)
{
    unsigned long h = 5381;
    while (*s) h = ((h << 5) + h) + (unsigned char)*s++;
    return h;
}

int ncm_http_request(const ncm_http_req_t *req, char *buf, size_t buf_sz, ncm_http_resp_t *resp)
{
    g_http_calls++;
    if (g_fail_next > 0) { g_fail_next--; return NCM_ERR_IO; }
    if (g_delay_ms > 0) usleep((useconds_t)g_delay_ms * 1000);
    size_t n = 4096 < buf_sz ? 4096 : buf_sz;
    unsigned long h = djb2(req->url);
    for (size_t i = 0; i < n; i++) buf[i] = (char)((h >> ((i % 8) * 8)) ^ (unsigned char)i);
    memset(resp, 0, sizeof *resp);
    resp->status = 200;
    resp->body = buf;
    resp->body_len = n;
    resp->content_length = n;
    return NCM_OK;
}

/* URL 期望内容哈希（与 stub 生成式一致） */
static unsigned long url_hash(const char *url)
{
    unsigned char tmp[4096];
    unsigned long h = djb2(url);
    for (size_t i = 0; i < sizeof tmp; i++) tmp[i] = (unsigned char)((h >> ((i % 8) * 8)) ^ (unsigned char)i);
    return fnv1a(tmp, sizeof tmp);
}

static int g_fail;
#define CHECK(cond, fmt, ...) do { \
    if (cond) printf("  PASS  " fmt "\n", ##__VA_ARGS__); \
    else { printf("  FAIL  " fmt "\n", ##__VA_ARGS__); g_fail = 1; } \
} while (0)

/* 轮询等待封面内容变成 want_hash（≤ ms）。返回 1=达成。 */
static int wait_cover_hash(unsigned long want, int ms)
{
    for (int t = 0; t < ms; t += 20) {
        meow_img *im = cover_get();
        unsigned long h = im ? im->hash : 0;
        cover_put();
        if (h == want) return 1;
        usleep(20 * 1000);
    }
    return 0;
}

static unsigned long cur_cover_hash(void)
{
    meow_img *im = cover_get();
    unsigned long h = im ? im->hash : 0;
    cover_put();
    return h;
}

/* 读 cover_current.jpg 并哈希（验证 launcher 媒体卡片读的文件同步更新）。 */
static unsigned long curjpg_hash(void)
{
    char path[600];
    snprintf(path, sizeof path, "%s/cover_current.jpg", g_st.cache_dir);
    FILE *f = fopen(path, "rb");
    if (!f) return 0;
    unsigned char b[4096];
    size_t n = fread(b, 1, sizeof b, f);
    fclose(f);
    return n ? fnv1a(b, n) : 0;
}

#define URL_A "http://p1.music.126.net/albumA/xxx.jpg"
#define URL_B "http://p1.music.126.net/albumB/yyy.jpg"
#define URL_C "http://p1.music.126.net/albumC/zzz.jpg"
#define URL_D "http://p1.music.126.net/albumD/www.jpg"

int main(void)
{
    if (system("rm -rf /tmp/ncm_cover_sim") != 0) { printf("FAIL  rm /tmp cache\n"); return 1; }
    memset(&g_st, 0, sizeof g_st);
    snprintf(g_st.cache_dir, sizeof g_st.cache_dir, "/tmp/ncm_cover_sim");
    ncm_cache_init(&g_st.ctx.cache, g_st.cache_dir);

    printf("== T1: first request -> cover appears ==\n");
    cover_request(URL_A);
    CHECK(wait_cover_hash(url_hash(URL_A), 3000), "cover A shown (hash match)");
    CHECK(g_http_calls == 1, "http calls=%d (expect 1)", g_http_calls);
    CHECK(curjpg_hash() == url_hash(URL_A), "cover_current.jpg == A");

    printf("== T2: settle -> worker idle (no busy loop) ==\n");
    cover_ack();
    int churn = 0;
    for (int t = 0; t < 1200; t += 10) { if (cover_changed()) churn++; usleep(10 * 1000); }
    CHECK(churn == 0, "cover_changed churn in 1.2s = %d (expect 0; §18 前=忙等死循环)", churn);
    CHECK(g_http_calls == 1, "http calls=%d (still 1)", g_http_calls);

    printf("== T3: switch song -> cover switches + cover_current.jpg updated ==\n");
    cover_request(URL_B);
    CHECK(wait_cover_hash(url_hash(URL_B), 3000), "cover switched to B");
    CHECK(curjpg_hash() == url_hash(URL_B), "cover_current.jpg == B");
    CHECK(g_http_calls == 2, "http calls=%d (expect 2)", g_http_calls);
    cover_ack();
    usleep(400 * 1000);
    CHECK(!cover_changed(), "no churn after switch");

    printf("== T4: re-request same url -> dedup ==\n");
    cover_request(URL_B);
    usleep(500 * 1000);
    CHECK(g_http_calls == 2, "http calls=%d (still 2, dedup)", g_http_calls);

    printf("== T5: flaky network x2 -> backoff retry succeeds ==\n");
    g_fail_next = 2;
    cover_request(URL_C);
    CHECK(wait_cover_hash(url_hash(URL_C), 8000), "cover C after retries");
    CHECK(g_http_calls >= 5, "http calls=%d (>=5: 2 fails + 1 ok for C)", g_http_calls);
    CHECK(g_log_warns >= 2, "warn logs=%d (failures logged, 不无声)", g_log_warns);

    printf("== T6: permanent failure -> give up after %d tries ==\n", 8);
    g_fail_next = 100;
    int before = g_http_calls;
    cover_request(URL_D);
    usleep(25 * 1000 * 1000 / 10);   /* ~2.5s 不够 8 次退避（0.5+1+2+4*5=23.5s），分段等 */
    for (int t = 0; t < 30 && g_http_calls - before < 8; t++) usleep(1000 * 1000);
    int tries = g_http_calls - before;
    CHECK(tries == 8, "give up after tries=%d (expect 8)", tries);
    CHECK(cur_cover_hash() == url_hash(URL_C), "old cover C retained after give-up");
    usleep(600 * 1000);
    CHECK(g_http_calls - before == 8, "no further retries after give-up (calls=%d)",
          g_http_calls - before);

    printf("== T7: null/empty + reset ==\n");
    cover_request(NULL);
    cover_request("");
    CHECK(g_http_calls == before + 8, "null/empty ignored (calls=%d)", g_http_calls);
    cover_cache_reset();
    CHECK(cur_cover_hash() == 0, "reset -> cover cleared");
    g_fail_next = 0;

    printf(g_fail ? "== COVER CHAIN SIM: FAIL ==\n" : "== COVER CHAIN SIM: ALL PASS ==\n");
    return g_fail;
}