/* logic/library.c — 书库目录扫描 + 自然排序（纯 C）。
 *
 * 扫描分两步：
 *   1) scan_info()：递归探测一个目录是否「最终含图」，并带回直接图片数 / 含图子目录数 /
 *      缩略图源（优先本目录自然序第一张，其次第一个含图子目录）；
 *   2) mr_library_scan()：只对目标目录的**直接子目录**调用 scan_info()，把 nav=1 的目录
 *      收进结果并自然排序——因此根视图不会列出后代条目，进入子目录时再重新扫描该层。
 *
 * 内存：条目数组倍增分配；路径/名称定长，随 mr_library_free() 释放。
 *
 * M7 追加（不改扫描语义）：
 *   - 续读角标：含图册的副标题后缀「· 续读 Pn」（读 logic/reader 的每册 last page）；
 *   - 册间衔接：mr_book_adjacent 给出同父目录下按书库自然序的相邻「含图册」，
 *     供阅读器末页前进/首页后退跨册；mr_library_dir_has_images 是共享的「是不是一本书」判据。
 *
 * M11 追加（档案册，仍然不改目录扫描的主体语义）：
 *   - 目标目录的**直接子文件**里 .cbz/.zip 也成行（行=文件名+档内页数，has_images=1）；
 *   - 档案册探测由调用方注入（mr_lib_archive_fn），logic 层不依赖 zip 容器；
 *     不注入时所有 *_ex 入口与 M7 行为逐字一致；
 *   - 册间衔接的兄弟表从「含图目录」扩成「含图目录 ∪ 含图片页的档案册」，同列自然序。
 *   小函数边界（add_dir_entry / add_archive_entry / entry_subtitle / entry_badge /
 *   sibling_is_book）刻意留给 M13 的书库重写复用。
 */
#include "library.h"
#include "logic/reader.h"   /* mr_cont_badge：书库行续读角标（M7） */

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

/* 系统目录不参与书库（SD 根上的 MeowOS 目录树）。 */
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);
}

typedef struct scan_info {
    int  pages;                   /* 直接图片数 */
    int  subdirs;                 /* 含图子目录数 */
    int  archives;                /* 直接档案册数（.cbz/.zip 且探测到图片页） */
    int  nav;                     /* 1=本目录最终含书（可直接看或可导航到书） */
    char cover[MR_PATH_MAX];      /* 缩略图源 */
    char first_name[MR_NAME_MAX]; /* 本目录自然序第一张图片的文件名（比较用） */
} scan_info;

/* 档案册探测（UI 注入；NULL=纯目录书库，行为与 M7 一致）。 */
static int archive_pages_at(mr_lib_archive_fn probe, void *ud, const char *path)
{
    if (!probe || !path || !path[0]) return 0;
    int n = probe(path, ud);
    return n > 0 ? n : 0;
}

static void scan_dir(const char *path, int depth, int max_depth, scan_info *si,
                     mr_lib_archive_fn probe, void *ud)
{
    memset(si, 0, sizeof *si);
    DIR *d = opendir(path);
    if (!d) return;

    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, path, name) != 0) continue;

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

        if (S_ISDIR(st.st_mode)) {
            if (depth >= max_depth) continue;
            scan_info child;
            scan_dir(full, depth + 1, max_depth, &child, probe, ud);
            if (!child.nav) continue;
            si->subdirs++;
            if (!si->cover[0] && child.cover[0])
                copy_str(si->cover, (int)sizeof si->cover, child.cover);
        } else if (S_ISREG(st.st_mode)) {
            if (mr_path_is_image(name)) {
                si->pages++;
                if (!si->first_name[0] || mr_natural_cmp(name, si->first_name) < 0) {
                    copy_str(si->first_name, (int)sizeof si->first_name, name);
                    copy_str(si->cover, (int)sizeof si->cover, full);
                }
            } else if (mr_path_is_archive(name)) {
                if (archive_pages_at(probe, ud, full) > 0) si->archives++;
            }
        }
    }
    closedir(d);
    si->nav = (si->pages > 0 || si->subdirs > 0 || si->archives > 0);
}

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

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;
    return mr_natural_cmp(a->name, b->name);
}

/* 副标题（M11 扩展）：直接含图 → pages；只有档案册 → books；否则 folders。 */
static void entry_subtitle(mr_library_entry *e, int archive_books)
{
    if (e->has_images)
        snprintf(e->subtitle, sizeof e->subtitle, "%d page%s", e->pages,
                 e->pages == 1 ? "" : "s");
    else if (archive_books > 0)
        snprintf(e->subtitle, sizeof e->subtitle, "%d book%s", archive_books,
                 archive_books == 1 ? "" : "s");
    else
        snprintf(e->subtitle, sizeof e->subtitle, "%d folder%s", e->subdirs,
                 e->subdirs == 1 ? "" : "s");
}

/* 续读角标（M7）：有 last page 记录的册，在副标题后缀「· 续读 Pn」。
 * 档案册以档案路径为册标识，同一套逻辑复用。
 * config 读失败/无记录时 mr_cont_badge 返回 0，副标题保持原样。 */
static void entry_badge(mr_library_entry *e)
{
    if (!e->has_images) return;
    char badge[24];
    if (!mr_cont_badge(e->path, badge, (int)sizeof badge)) return;
    int used = (int)strlen(e->subtitle);
    if (used < (int)sizeof e->subtitle - 2)
        snprintf(e->subtitle + used, sizeof e->subtitle - (size_t)used, " · %s", badge);
}

/* 文件夹册（含可导航中间目录）一行。 */
static int add_dir_entry(mr_library *lib, const char *name, const char *full,
                         const scan_info *si)
{
    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;
    copy_str(e.cover, (int)sizeof e.cover, si->cover);
    e.pages = si->pages;
    e.subdirs = si->subdirs;
    e.has_images = (si->pages > 0);
    entry_subtitle(&e, si->archives);
    entry_badge(&e);
    return lib_add(lib, &e);
}

/* 档案册（.cbz/.zip）一行：文件即一本书，点入直接阅读。
 * cover 留空——缩略图由 UI 解压档内首图（mr_zip_cover_path）生成。 */
static int add_archive_entry(mr_library *lib, const char *name, const char *full,
                             int pages)
{
    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.pages = pages;
    e.subdirs = 0;
    e.has_images = 1;
    snprintf(e.subtitle, sizeof e.subtitle, "%d page%s", pages, pages == 1 ? "" : "s");
    entry_badge(&e);
    return lib_add(lib, &e);
}

int mr_library_scan_ex(mr_library *lib, const char *dir, int max_depth,
                       mr_lib_archive_fn archive_pages, void *ud)
{
    if (!lib) return -1;
    mr_library_free(lib);
    if (!dir || !dir[0]) return -1;

    if (max_depth <= 0 || max_depth > MR_LIB_MAX_DEPTH) max_depth = MR_LIB_MAX_DEPTH;

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

    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, dir, name) != 0) continue;

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

        int rc = 0;
        if (S_ISDIR(st.st_mode)) {
            scan_info si;
            scan_dir(full, 1, max_depth, &si, archive_pages, ud);
            if (!si.nav) continue;
            rc = add_dir_entry(lib, name, full, &si);
        } else if (S_ISREG(st.st_mode) && mr_path_is_archive(name)) {
            int pages = archive_pages_at(archive_pages, ud, full);
            if (pages <= 0) continue;              /* 坏档/无图片页：不当书 */
            rc = add_archive_entry(lib, name, full, pages);
        } else {
            continue;
        }
        if (rc != 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_scan(mr_library *lib, const char *dir, int max_depth)
{
    return mr_library_scan_ex(lib, dir, max_depth, NULL, NULL);
}

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）                                                */
/* ============================================================ */
int mr_library_dir_has_images(const char *dir)
{
    if (!dir || !dir[0]) return 0;
    DIR *d = opendir(dir);
    if (!d) return 0;

    int found = 0;
    struct dirent *de;
    while ((de = readdir(d)) != NULL) {
        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;
        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;
        return archive_pages_at(probe, ud, full) > 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 || 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(const char *dir, int delta, char *out, int outsz)
{
    return mr_book_adjacent_ex(dir, delta, out, outsz, NULL, NULL);
}