/* logic/library.c — 书库文件管理器模型：单层枚举 + 纯内存行合成（纯 C）。
 *
 * 扫描（mr_library_scan）与 os.meow.files 的 fsx_scan_dir 同构：
 *   - 一次 opendir/readdir，逐项 lstat（只认目录、受支持图片、.cbz/.zip；符号链接跳过防环）；
 *   - 隐藏项（"." 开头，含 . ..）跳过；空目录/无图目录/系统目录照常列出；
 *   - 排序：目录优先，组内按 mr_natural_cmp 自然升序；
 *   - 副标题（类型 · 大小）在扫描期生成一次，渲染期不再做任何格式化/IO；
 *   - 条目到 MR_LIB_SCAN_MAX 后仍有条目 → 截断标注。
 *
 * 阅读器辅助（与列表模型解耦）：mr_library_dir_has_images 单层判据 +
 * mr_book_adjacent(_ex) 兄弟册衔接（M7/M11 阅读器翻到相邻册用）。
 */
#include "library.h"

#include <ctype.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/stat.h>

#ifdef MR_LIBRARY_TEST_HOOKS
static mr_library_io_stats g_io;

void mr_library_test_io_reset(void)
{
    memset(&g_io, 0, sizeof g_io);
}

void mr_library_test_io_get(mr_library_io_stats *out)
{
    if (out) *out = g_io;
}

#define IO_OPEN()    (g_io.opendirs++)
#define IO_READDIR() (g_io.readdirs++)
#define IO_LSTAT()   (g_io.lstats++)
#else
#define IO_OPEN()    ((void)0)
#define IO_READDIR() ((void)0)
#define IO_LSTAT()   ((void)0)
#endif

/* 系统目录不参与**册间衔接**（M7 兄弟册表）；浏览本身已放开（不隐藏）。 */
static int ignored_dir_name(const char *name)
{
    static const char *const skip[] = { "MeowAPPs", "MeowData", "MeowOS", "lost+found" };
    if (!name || name[0] == '.') return 1;
    for (unsigned i = 0; i < sizeof skip / sizeof skip[0]; i++)
        if (strcmp(name, skip[i]) == 0) return 1;
    return 0;
}

static int copy_str(char *dst, int dstsz, const char *src)
{
    if (!dst || dstsz <= 0) return -1;
    if (!src) { dst[0] = '\0'; return 0; }
    int n = (int)strlen(src);
    if (n >= dstsz) return -1;
    memcpy(dst, src, (size_t)n + 1);
    return 0;
}

static int join_path(char *out, int outsz, const char *dir, const char *name)
{
    if (!out || outsz <= 0 || !dir || !name) return -1;
    int n;
    size_t dl = strlen(dir);
    if (dl > 0 && dir[dl - 1] == '/')
        n = snprintf(out, (size_t)outsz, "%s%s", dir, name);
    else
        n = snprintf(out, (size_t)outsz, "%s/%s", dir, name);
    return (n > 0 && n < outsz) ? 0 : -1;
}

int mr_path_is_image(const char *name)
{
    if (!name) return 0;
    const char *dot = strrchr(name, '.');
    if (!dot || dot == name) return 0;
    dot++;
    return strcasecmp(dot, "png") == 0 || strcasecmp(dot, "jpg") == 0 ||
           strcasecmp(dot, "jpeg") == 0 || strcasecmp(dot, "bmp") == 0;
}

int mr_path_is_archive(const char *name)
{
    if (!name) return 0;
    const char *dot = strrchr(name, '.');
    if (!dot || dot == name) return 0;
    dot++;
    return strcasecmp(dot, "cbz") == 0 || strcasecmp(dot, "zip") == 0;
}

int mr_natural_cmp(const char *a, const char *b)
{
    const unsigned char *pa = (const unsigned char *)a;
    const unsigned char *pb = (const unsigned char *)b;
    if (!a || !b) return (a == b) ? 0 : (a ? 1 : -1);

    while (*pa && *pb) {
        if (isdigit(*pa) && isdigit(*pb)) {
            const unsigned char *za = pa, *zb = pb;
            while (*pa == '0') pa++;
            while (*pb == '0') pb++;
            const unsigned char *da = pa, *db = pb;
            while (isdigit(*pa)) pa++;
            while (isdigit(*pb)) pb++;

            size_t la = (size_t)(pa - da), lb = (size_t)(pb - db);
            if (la != lb) return la < lb ? -1 : 1;
            if (la > 0) {
                int c = memcmp(da, db, la);
                if (c != 0) return c < 0 ? -1 : 1;
            }
            size_t oa = (size_t)(da - za), ob = (size_t)(db - zb);
            if (oa != ob) return oa < ob ? -1 : 1;
            continue;
        }

        int ca = tolower(*pa), cb = tolower(*pb);
        if (ca != cb) return ca < cb ? -1 : 1;
        pa++;
        pb++;
    }
    if (*pa) return 1;
    if (*pb) return -1;
    return strcmp(a, b) < 0 ? -1 : (strcmp(a, b) > 0 ? 1 : 0);
}

/* ============================================================ */
/* 扫描 / 排序 / 行合成                                           */
/* ============================================================ */
static void fmt_size(long long size, char *out, int outsz)
{
    if (size < 0) size = 0;
    static const char *const unit[] = { "B", "KB", "MB", "GB" };
    double v = (double)size;
    int i = 0;
    while (v >= 1024.0 && i < 3) { v /= 1024.0; i++; }
    if (i == 0) snprintf(out, (size_t)outsz, "%lld B", size);
    else        snprintf(out, (size_t)outsz, "%.1f %s", v, unit[i]);
}

/* 副标题只在扫描期生成一次（渲染期零格式化）。 */
static void format_subtitle(mr_library_entry *e)
{
    char sz[32];
    switch (e->kind) {
    case MR_LIB_KIND_DIR:
        snprintf(e->subtitle, sizeof e->subtitle, "文件夹");
        break;
    case MR_LIB_KIND_ARCHIVE:
        fmt_size(e->size, sz, (int)sizeof sz);
        snprintf(e->subtitle, sizeof e->subtitle, "档案册 · %s", sz);
        break;
    default:
        fmt_size(e->size, sz, (int)sizeof sz);
        snprintf(e->subtitle, sizeof e->subtitle, "图片 · %s", sz);
        break;
    }
}

void mr_library_free(mr_library *lib)
{
    if (!lib) return;
    free(lib->items);
    lib->items = NULL;
    lib->count = 0;
    lib->cap = 0;
    lib->truncated = 0;
}

static int lib_add(mr_library *lib, const mr_library_entry *e)
{
    if (lib->count >= lib->cap) {
        int cap = lib->cap ? lib->cap * 2 : 16;
        mr_library_entry *ni = (mr_library_entry *)realloc(lib->items,
                                                           (size_t)cap * sizeof *ni);
        if (!ni) return -1;
        lib->items = ni;
        lib->cap = cap;
    }
    lib->items[lib->count++] = *e;
    return 0;
}

/* 目录优先；组内自然序（大小写不敏感 + 原始字节兜底，结果确定）。 */
static int entry_cmp(const void *pa, const void *pb)
{
    const mr_library_entry *a = (const mr_library_entry *)pa;
    const mr_library_entry *b = (const mr_library_entry *)pb;
    int ad = (a->kind == MR_LIB_KIND_DIR), bd = (b->kind == MR_LIB_KIND_DIR);
    if (ad != bd) return ad ? -1 : 1;
    return mr_natural_cmp(a->name, b->name);
}

static int add_entry(mr_library *lib, const char *name, const char *full,
                     int kind, const struct stat *st)
{
    mr_library_entry e;
    memset(&e, 0, sizeof e);
    if (copy_str(e.name, (int)sizeof e.name, name) != 0) return 0;
    if (copy_str(e.path, (int)sizeof e.path, full) != 0) return 0;
    e.kind = kind;
    e.size = (kind == MR_LIB_KIND_DIR) ? 0 : (long long)st->st_size;
    format_subtitle(&e);
    return lib_add(lib, &e);
}

int mr_library_scan(mr_library *lib, const char *dir, int max_depth)
{
    (void)max_depth;   /* 兼容旧签名：扫描不递归 */
    if (!lib) return -1;
    mr_library_free(lib);
    if (!dir || !dir[0]) return -1;

    IO_OPEN();
    DIR *d = opendir(dir);
    if (!d) return -1;

    struct dirent *de;
    while ((de = readdir(d)) != NULL) {
        IO_READDIR();
        const char *name = de->d_name;
        if (name[0] == '.') continue;      /* . .. 与隐藏项 */

        char full[MR_PATH_MAX];
        if (join_path(full, (int)sizeof full, dir, name) != 0) continue;

        IO_LSTAT();
        struct stat st;
        if (lstat(full, &st) != 0) continue;
        if (S_ISLNK(st.st_mode)) continue;

        int kind;
        if (S_ISDIR(st.st_mode))                       kind = MR_LIB_KIND_DIR;
        else if (!S_ISREG(st.st_mode))                 continue;
        else if (mr_path_is_image(name))               kind = MR_LIB_KIND_IMAGE;
        else if (mr_path_is_archive(name))             kind = MR_LIB_KIND_ARCHIVE;
        else                                           continue;

        if (lib->count >= MR_LIB_SCAN_MAX) { lib->truncated = 1; break; }
        if (add_entry(lib, name, full, kind, &st) != 0) {
            closedir(d);
            mr_library_free(lib);
            return -1;
        }
    }
    closedir(d);

    if (lib->count > 1)
        qsort(lib->items, (size_t)lib->count, sizeof *lib->items, entry_cmp);
    return lib->count;
}

int mr_library_row_at(const mr_library *lib, int idx, mr_library_row *out)
{
    static char trunc_sub[96];
    static int  trunc_ready;

    if (!lib || !out) return 0;
    if (idx == lib->count && lib->truncated) {
        if (!trunc_ready) {
            /* 截断只是列表显示上限：图片仍能从任一可见图片进入阅读器后翻到，
             * 文案不要让人误以为「没有更多图片」。 */
            snprintf(trunc_sub, sizeof trunc_sub,
                     "仅显示前 %d 项（图片可在阅读器中翻到）", MR_LIB_SCAN_MAX);
            trunc_ready = 1;
        }
        memset(out, 0, sizeof *out);
        out->title = "已截断";
        out->subtitle = trunc_sub;
        out->disabled = 1;
        out->index = -1;
        return 1;
    }
    if (idx < 0 || idx >= lib->count) return 0;

    const mr_library_entry *e = &lib->items[idx];
    memset(out, 0, sizeof *out);
    out->title = e->name;
    out->subtitle = e->subtitle;
    out->kind = e->kind;
    out->index = idx;
    return 1;
}

int mr_path_within_root(const char *path, const char *root)
{
    if (!path || !path[0] || !root || !root[0]) return 0;
    size_t rl = strlen(root);
    while (rl > 1 && root[rl - 1] == '/') rl--;
    if (rl == 1 && root[0] == '/') return path[0] == '/';
    if (strncmp(path, root, rl) != 0) return 0;
    char c = path[rl];
    return c == '\0' || c == '/';
}

int mr_path_parent(const char *path, char *out, int outsz)
{
    if (!path || !out || outsz <= 0) return -1;
    size_t n = strlen(path);
    while (n > 1 && path[n - 1] == '/') n--;
    if (n <= 1) {
        if (outsz < 2) return -1;
        out[0] = '/';
        out[1] = '\0';
        return 0;
    }
    while (n > 0 && path[n - 1] != '/') n--;
    while (n > 1 && path[n - 1] == '/') n--;
    if (n >= (size_t)outsz) return -1;
    memcpy(out, path, n);
    out[n] = '\0';
    return 0;
}

/* ============================================================ */
/* 册间衔接（M7 / M11）                                          */
/* ============================================================ */
int mr_library_dir_has_images(const char *dir)
{
    if (!dir || !dir[0]) return 0;
    IO_OPEN();
    DIR *d = opendir(dir);
    if (!d) return 0;

    int found = 0;
    struct dirent *de;
    while ((de = readdir(d)) != NULL) {
        IO_READDIR();
        const char *name = de->d_name;
        if (name[0] == '.' || !mr_path_is_image(name)) continue;
        char full[MR_PATH_MAX];
        if (join_path(full, (int)sizeof full, dir, name) != 0) continue;
        IO_LSTAT();
        struct stat st;
        if (lstat(full, &st) != 0 || !S_ISREG(st.st_mode)) continue;
        found = 1;
        break;
    }
    closedir(d);
    return found;
}

static int name_ptr_cmp(const void *pa, const void *pb)
{
    const char *a = *(const char *const *)pa;
    const char *b = *(const char *const *)pb;
    return mr_natural_cmp(a, b);
}

/* 兄弟册判据（M11）：目录=直接含图；普通文件=档案册且有图片页。
 * 两者同列，交给 name_ptr_cmp 自然序混排。 */
static int sibling_is_book(const char *full, const struct stat *st,
                           mr_lib_archive_fn probe, void *ud)
{
    if (S_ISDIR(st->st_mode)) return mr_library_dir_has_images(full);
    if (S_ISREG(st->st_mode)) {
        const char *slash = strrchr(full, '/');
        const char *name = slash ? slash + 1 : full;
        if (!mr_path_is_archive(name)) return 0;
        if (!probe) return 0;
        int n = probe(full, ud);
        return n > 0;
    }
    return 0;
}

int mr_book_adjacent_ex(const char *dir, int delta, char *out, int outsz,
                        mr_lib_archive_fn archive_pages, void *ud)
{
    if (!out || outsz <= 0) return -1;
    out[0] = '\0';
    if (!dir || !dir[0] || (delta != 1 && delta != -1)) return -1;

    char norm[MR_PATH_MAX];
    size_t dl = strlen(dir);
    while (dl > 1 && dir[dl - 1] == '/') dl--;
    if (dl >= sizeof norm) return -1;
    memcpy(norm, dir, dl);
    norm[dl] = '\0';

    const char *slash = strrchr(norm, '/');
    if (!slash || !slash[1]) return -1;
    const char *cur = slash + 1;

    char parent[MR_PATH_MAX];
    if (mr_path_parent(norm, parent, (int)sizeof parent) != 0) return -1;

    DIR *d = opendir(parent);
    if (!d) return 0;

    char **names = NULL;
    int n = 0, cap = 0;
    struct dirent *de;
    while ((de = readdir(d)) != NULL) {
        const char *name = de->d_name;
        if (strcmp(name, ".") == 0 || strcmp(name, "..") == 0) continue;
        if (ignored_dir_name(name)) continue;

        char full[MR_PATH_MAX];
        if (join_path(full, (int)sizeof full, parent, name) != 0) continue;
        struct stat st;
        if (lstat(full, &st) != 0) continue;
        if (S_ISLNK(st.st_mode)) continue;
        if (!sibling_is_book(full, &st, archive_pages, ud)) continue;

        if (n >= cap) {
            int nc = cap ? cap * 2 : 16;
            char **nn = (char **)realloc(names, (size_t)nc * sizeof *nn);
            if (!nn) break;
            names = nn;
            cap = nc;
        }
        size_t len = strlen(name);
        names[n] = (char *)malloc(len + 1);
        if (!names[n]) break;
        memcpy(names[n], name, len + 1);
        n++;
    }
    closedir(d);

    int rc = 0;
    if (n > 1) qsort(names, (size_t)n, sizeof *names, name_ptr_cmp);
    int idx = -1;
    for (int i = 0; i < n; i++)
        if (strcmp(names[i], cur) == 0) { idx = i; break; }
    int target = idx + delta;
    if (idx >= 0 && target >= 0 && target < n) {
        if (join_path(out, outsz, parent, names[target]) == 0) rc = 1;
    }
    for (int i = 0; i < n; i++) free(names[i]);
    free(names);
    return rc;
}

int mr_book_adjacent_rooted(const char *dir, int delta, const char *root,
                            mr_lib_archive_fn archive_pages, void *ud,
                            char *out, int outsz)
{
    if (!out || outsz <= 0) return -1;
    out[0] = '\0';
    if (!dir || !dir[0] || !root || !root[0]) return -1;
    /* 只允许在浏览根内翻册：当前册或相邻册越根一律当「没有相邻册」。 */
    if (!mr_path_within_root(dir, root)) return 0;

    int r = mr_book_adjacent_ex(dir, delta, out, outsz, archive_pages, ud);
    if (r != 1) return r;
    if (!mr_path_within_root(out, root)) {
        out[0] = '\0';
        return 0;
    }
    return 1;
}

int mr_book_adjacent(const char *dir, int delta, char *out, int outsz)
{
    return mr_book_adjacent_ex(dir, delta, out, outsz, NULL, NULL);
}