/* test/shelf_index_bench.c — M32 索引方案可行性计时（宿主，纯 C + clock_gettime）。
 *
 * 用法：
 *   ./shelf_index_bench_host [bench|indexonly] [root]
 *     bench      —— 建虚拟书库（默认 452 目录 / 688 本，贴合真机 434/595 量级）并计时
 *     indexonly  —— 只载入已有索引一次（供 `strace -e getdents64` 断言「载入不 readdir」）
 *
 * 为什么宿主数字不能直接当真机用：宿主是 ext4/f2fs 热缓存（每次 stat ~1µs），真机 TF 卡是
 * exFAT（M28 实测 1079 次 stat = 160–170ms，约 150µs/次）。本工具用来量**调用次数与代码路径**
 * 的相对成本；绝对毫秒按 M28 的每次 stat/条目成本外推（见报文）。
 *
 * 计时口径：
 *   - stat_all     ：先 opendir 走一遍把目录列表收好（不计时），再单独循环 stat（计时的只有 stat）；
 *   - full_scan    ：shelf_scan_books_ex（生产全量扫描形态，ts_fn=NULL）；
 *   - scan+save    ：全量扫描 + 索引落盘（生产「无索引首次进入」路径）；
 *   - index_load   ：shelf_index_load 命中（生产「有索引首次进入」路径，ts_fn=NULL 以隔离进度读）；
 *   - index_read   ：单次 open+fstat+read 整个索引文件（校验之前的纯 IO 成本）。
 */
#include "shelf_model.h"
#include "shelf_index.h"

#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>

static char g_cfgdir[500];
const char *meow_config_dir(void) { return g_cfgdir; }

static double now_ms(void)
{
    struct timespec ts;
    clock_gettime(CLOCK_MONOTONIC, &ts);
    return (double)ts.tv_sec * 1000.0 + (double)ts.tv_nsec / 1e6;
}

static void mkdirs(const char *path)
{
    char t[600];
    snprintf(t, sizeof t, "%s", path);
    for (char *p = t + 1; *p; p++) {
        if (*p == '/') { *p = 0; mkdir(t, 0755); *p = '/'; }
    }
    mkdir(t, 0755);
}

static void put_file(const char *path, long size)
{
    FILE *f = fopen(path, "wb");
    if (!f) return;
    fseek(f, size > 0 ? size - 1 : 0, SEEK_SET);
    fputc('x', f);
    fclose(f);
}

/* 虚拟书库：精确复刻真机量级 —— 434 个目录 / 595 本书 / 51 个 .rar（不支持格式）。
 *   根 1 + 一级 10 + 「400+本高质量完本合集」下 40 分类 + 382 作品目录 + 轻小说/子目录 1 = 434；
 *   书 = 382 作品 × 1 + 其它 9 个一级目录 × 20 + 根 3 + 子目录 30 = 595。 */
static int make_library(const char *root)
{
    char p[600];
    DIR *d = opendir(root);
    if (d) { closedir(d); return 0; }   /* 已存在：复用 */
    mkdirs(root);
    const char *l1[] = { "400+本高质量完本合集", "轻小说", "玄幻", "都市", "科幻",
                         "历史", "武侠", "游戏", "悬疑", "同人科幻" };
    for (size_t i = 0; i < sizeof l1 / sizeof l1[0]; i++) {
        snprintf(p, sizeof p, "%s/%s", root, l1[i]); mkdirs(p);
    }
    int works = 0, rar = 0;
    /* 40 个分类目录，382 个作品目录（前 22 个分类各 10 个，其余各 9 个）：
     * 1 根 + 10 一级 + 40 分类 + 382 作品 + 1 子目录 = 434 个目录。 */
    for (int c = 1; c <= 40; c++) {
        snprintf(p, sizeof p, "%s/400+本高质量完本合集/%02d、分类%d", root, c, c); mkdirs(p);
        int nw = (c <= 22) ? 10 : 9;
        for (int w = 1; w <= nw; w++, works++) {
            char wd[600];
            snprintf(wd, sizeof wd, "%s/400+本高质量完本合集/%02d、分类%d/%02d、作品%d",
                     root, c, c, w, w);
            mkdirs(wd);
            snprintf(p, sizeof p, "%s/第1卷.txt", wd);
            put_file(p, 1024 + (long)((works * 7919) % 200000));
            if ((works % 7) == 0 && rar < 51) { snprintf(p, sizeof p, "%s/合集.rar", wd); put_file(p, 1000); rar++; }
        }
    }
    for (size_t i = 1; i < sizeof l1 / sizeof l1[0]; i++) {
        for (int b = 1; b <= 20; b++) {
            snprintf(p, sizeof p, "%s/%s/书%d.txt", root, l1[i], b);
            put_file(p, 4096);
        }
    }
    for (int b = 1; b <= 3; b++) {
        snprintf(p, sizeof p, "%s/根下%d.txt", root, b);
        put_file(p, 2048);
    }
    snprintf(p, sizeof p, "%s/轻小说/子目录", root); mkdirs(p);
    for (int b = 1; b <= 30; b++) {
        snprintf(p, sizeof p, "%s/轻小说/子目录/深%d.txt", root, b);
        put_file(p, 4096);
    }
    /* 补齐 51 个 rar（若作品目录里不够，放到一级目录） */
    while (rar < 51) {
        snprintf(p, sizeof p, "%s/玄幻/压缩%d.rar", root, rar);
        put_file(p, 100);
        rar++;
    }
    return 1;
}

/* 收集目录列表（不计时；用于单独量 stat 成本）。 */
static int collect_dirs(const char *dir, char paths[][512], int max, int n, int depth)
{
    if (depth > 8 || n >= max) return n;
    DIR *d = opendir(dir);
    if (!d) return n;
    struct dirent *e;
    while ((e = readdir(d))) {
        if (e->d_name[0] == '.') continue;
        char path[512];
        if (snprintf(path, sizeof path, "%s/%s", dir, e->d_name) >= (int)sizeof path) continue;
        struct stat st;
        if (stat(path, &st) != 0) continue;
        if (S_ISDIR(st.st_mode) && n < max) {
            snprintf(paths[n], 512, "%s", path);
            n = collect_dirs(path, paths, max, n + 1, depth + 1);
        }
    }
    closedir(d);
    return n;
}

static int count_files(const char *dir, int depth)
{
    if (depth > 8) return 0;
    DIR *d = opendir(dir);
    if (!d) return 0;
    int n = 0;
    struct dirent *e;
    while ((e = readdir(d))) {
        if (e->d_name[0] == '.') continue;
        char path[512];
        snprintf(path, sizeof path, "%s/%s", dir, e->d_name);
        struct stat st;
        if (stat(path, &st) != 0) continue;
        if (S_ISDIR(st.st_mode)) n += count_files(path, depth + 1);
        else n++;
    }
    closedir(d);
    return n;
}

int main(int argc, char **argv)
{
    const char *mode = (argc > 1) ? argv[1] : "bench";
    const char *tmp = getenv("TMPDIR");
    if (!tmp || !tmp[0]) tmp = "/tmp";
    char base[500], root[520];
    if (argc > 2) snprintf(base, sizeof base, "%s", argv[2]);
    else snprintf(base, sizeof base, "%s/m32bench", tmp);
    snprintf(root, sizeof root, "%s/Books", base);
    snprintf(g_cfgdir, sizeof g_cfgdir, "%s/data", base);
    mkdirs(g_cfgdir);

    static shelf_book books[SHELF_MAX_BOOKS];
    shelf_scan_report rep;

    if (strcmp(mode, "indexonly") == 0) {
        int hit = shelf_index_load(root, books, SHELF_MAX_BOOKS, NULL, &rep);
        printf("indexonly hit=%d nbooks=%d\n", hit, rep.nbooks);
        return hit ? 0 : 1;
    }

    int created = make_library(root);
    static char dirs[4096][512];
    snprintf(dirs[0], 512, "%s", root);
    int nd = 1 + collect_dirs(root, dirs, 4096, 0, 0);
    int nfiles = count_files(root, 0);
    printf("library: %s (%s) dirs=%d files=%d\n", root, created ? "created" : "reused", nd, nfiles);

    /* ① 目录逐个 stat（校验索引的唯一 IO） */
    struct stat st;
    int reps = 20;
    double t0 = now_ms();
    for (int r = 0; r < reps; r++)
        for (int i = 0; i < nd; i++) stat(dirs[i], &st);
    double t1 = now_ms();
    printf("stat_all_dirs: %d x%d = %.2f ms total, %.3f ms/pass, %.2f us/stat\n",
           nd, reps, t1 - t0, (t1 - t0) / reps, (t1 - t0) * 1000.0 / (reps * nd));

    /* ② 全量扫描（无 ts） */
    double best_scan = 1e9, best_save = 1e9;
    int n = 0;
    for (int r = 0; r < 3; r++) {
        double a = now_ms();
        n = shelf_scan_books_ex(root, books, SHELF_MAX_BOOKS, NULL, &rep, NULL, NULL);
        double b = now_ms();
        if (b - a < best_scan) best_scan = b - a;
    }
    printf("full_scan: books=%d truncated=%d depth_skipped=%d best=%.2f ms\n",
           n, rep.truncated, rep.depth_skipped, best_scan);
    int scan_trunc = rep.truncated, scan_skip = rep.depth_skipped;

    /* ③ 全量扫描 + 写索引 */
    for (int r = 0; r < 3; r++) {
        double a = now_ms();
        shelf_idx_writer *w = shelf_index_writer_open(root);
        int n2 = shelf_scan_books_ex(root, books, SHELF_MAX_BOOKS, NULL, &rep,
                                     w ? shelf_index_writer_dir : NULL, w);
        int ok = w ? shelf_index_writer_commit(w, books, n2, &rep) : 0;
        double b = now_ms();
        if (b - a < best_save) best_save = b - a;
        if (r == 0) printf("scan+save: scan_books=%d index_commit=%d\n", n2, ok);
    }
    printf("scan+save: best=%.2f ms\n", best_save);

    /* ④ 索引命中（不含 ts 读取） */
    double best_load = 1e9;
    int hit = 0, ln = 0;
    for (int r = 0; r < 5; r++) {
        double a = now_ms();
        hit = shelf_index_load(root, books, SHELF_MAX_BOOKS, NULL, &rep);
        double b = now_ms();
        ln = rep.nbooks;
        if (b - a < best_load) best_load = b - a;
    }
    printf("index_load: hit=%d nbooks=%d best=%.2f ms\n", hit, ln, best_load);

    /* ⑤ 索引文件大小 + 单次顺序读成本 */
    char ip[600];
    if (shelf_index_path(root, ip, sizeof ip) == 0 && stat(ip, &st) == 0) {
        char *buf = (char *)malloc((size_t)st.st_size);
        double a = now_ms();
        for (int r = 0; r < 20 && buf; r++) {
            FILE *f = fopen(ip, "rb");
            if (f) { if (fread(buf, 1, (size_t)st.st_size, f) != (size_t)st.st_size) { /* 短读 */ } fclose(f); }
        }
        double b = now_ms();
        printf("index_file: %lld bytes, open+read %.3f ms/pass\n",
               (long long)st.st_size, buf ? (b - a) / 20 : 0.0);
        free(buf);
    }

    /* ⑥ 生产路径估算：索引命中 + 595 次 rdprog_load（M28 实测 40–50ms，未在此重复测） */
    printf("NOTE 生产路径 = index_load + rdprog_load×nbooks（M28: 40–50ms）+ build_rows(<20ms)\n");

    /* ⑦ 模拟真机书库的正确性断言：595 本全可见、无截断、无超深跳过，索引与扫描同数。 */
    int pass = (n == 595 && ln == 595 && hit == 1 && scan_trunc == 0 && scan_skip == 0);
    printf("CHECK library_sim scan_books=%d load_books=%d hit=%d truncated=%d depth_skipped=%d -> %s\n",
           n, ln, hit, scan_trunc, scan_skip, pass ? "PASS" : "FAIL");
    return pass ? 0 : 1;
}