#include <c_FileIter.h>
#include <stdio.h>
#include <c_Memory.h>

/* ------------------------------------------------------------------------------------------------------------------ */
/*  */


#ifdef _WIN32
    #include <windows.h>
    typedef struct {
        HANDLE hFind;
        WIN32_FIND_DATAA findData;
    } WinIterCtx;
#else

#ifndef _FILE_OFFSET_BITS
#define _FILE_OFFSET_BITS 64
#endif

#include <sys/types.h>
#include <dirent.h>
#include <sys/stat.h>
#include <unistd.h>

typedef struct {
    DIR* dir;
} PosixIterCtx;

#endif


/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

// 内部辅助函数：获取下一个有效条目（过滤 "." 和 ".."）
static void c_FileIter_InternalFetch(c_FileIter_t* iter) {
#ifdef _WIN32
    WinIterCtx* ctx = (WinIterCtx*)iter->internal_ctx;
    while (FindNextFileA(ctx->hFind, &ctx->findData)) {
        if (strcmp(ctx->findData.cFileName, ".") == 0 || strcmp(ctx->findData.cFileName, "..") == 0) {
            continue; // 过滤
        }
        // 填充缓存
        strncpy(iter->current.name, ctx->findData.cFileName, sizeof(iter->current.name) - 1);
        iter->current.name[sizeof(iter->current.name) - 1] = '\0';

        if (ctx->findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
            iter->current.type = C_FILE_TYPE_DIR;
            iter->current.size = 0;
        } else {
            iter->current.type = C_FILE_TYPE_REGULAR;
            iter->current.size = ((unsigned long long)ctx->findData.nFileSizeHigh << 32) | ctx->findData.nFileSizeLow;
        }
        iter->has_next = C_TRUE;
        return;
    }
#else
    PosixIterCtx* ctx = (PosixIterCtx*)iter->internal_ctx;
    struct dirent* entry;
    while ((entry = readdir(ctx->dir)) != NULL) {
        if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
            continue; // 过滤
        }
        // 填充名字
        strncpy(iter->current.name, entry->d_name, sizeof(iter->current.name) - 1);
        iter->current.name[sizeof(iter->current.name) - 1] = '\0';

        // 组装完整路径获取大文件大小及类型
        char full_path[512];
        snprintf(full_path, sizeof(full_path), "%s/%s", iter->base_path, entry->d_name);
        struct stat stat_buf;

        if (stat(full_path, &stat_buf) == 0) {
            iter->current.size = (unsigned long long)stat_buf.st_size;
            if (S_ISDIR(stat_buf.st_mode)) {
                iter->current.type = C_FILE_TYPE_DIR;
            } else if (S_ISREG(stat_buf.st_mode)) {
                iter->current.type = C_FILE_TYPE_REGULAR;
            } else {
                iter->current.type = C_FILE_TYPE_UNKNOWN;
            }
        } else {
            iter->current.type = C_FILE_TYPE_UNKNOWN;
            iter->current.size = 0;
        }
        iter->has_next = C_TRUE;
        return;
    }
#endif

    // 没有更多文件了，触发自动资源清理
    iter->has_next = C_FALSE;
    if (iter->internal_ctx) {
#ifdef _WIN32
        FindClose(((WinIterCtx*)iter->internal_ctx)->hFind);
#else
        closedir(((PosixIterCtx*)iter->internal_ctx)->dir);
#endif
        C_FREE(iter->internal_ctx);
        iter->internal_ctx = NULL;
    }
}


/* ------------------------------------------------------------------------------------------------------------------ */
/*  */

c_err_t c_FileIter_Init(c_FileIter_t* iter, const char* dirpath) {
    if (!iter || !dirpath) return C_ERR_FAIL;

    iter->internal_ctx = NULL;
    iter->has_next = C_FALSE;
    strncpy(iter->base_path, dirpath, sizeof(iter->base_path) - 1);
    iter->base_path[sizeof(iter->base_path) - 1] = '\0';

#ifdef _WIN32
    WinIterCtx* ctx = (WinIterCtx*)C_ALLOC(sizeof(WinIterCtx));
    if (!ctx) return C_ERR_FAIL;

    char search_path[512];
    snprintf(search_path, sizeof(search_path), "%s\\*", dirpath);

    ctx->hFind = FindFirstFile(search_path, &ctx->findData);
    if (ctx->hFind == INVALID_HANDLE_VALUE) {
        C_FREE(ctx);
        return C_ERR_FAIL;
    }
    iter->internal_ctx = ctx;

    // 检查第一个读取到的是否是 "." 或 ".."，如果是，则继续查找有效文件
    if (strcmp(ctx->findData.cFileName, ".") == 0 || strcmp(ctx->findData.cFileName, "..") == 0) {
        c_FileIter_InternalFetch(iter);
    } else {
        strncpy(iter->current.name, ctx->findData.cFileName, sizeof(iter->current.name) - 1);
        iter->current.name[sizeof(iter->current.name) - 1] = '\0';
        if (ctx->findData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
            iter->current.type = C_FILE_TYPE_DIR;
            iter->current.size = 0;
        } else {
            iter->current.type = C_FILE_TYPE_REGULAR;
            iter->current.size = ((unsigned long long)ctx->findData.nFileSizeHigh << 32) | ctx->findData.nFileSizeLow;
        }
        iter->has_next = C_TRUE;
    }
#else
    PosixIterCtx* ctx = (PosixIterCtx*)C_ALLOC(sizeof(PosixIterCtx));
    if (!ctx) return C_ERR_FAIL;

    ctx->dir = opendir(dirpath);
    if (!ctx->dir) {
        C_FREE(ctx);
        return C_ERR_FAIL;
    }
    iter->internal_ctx = ctx;

    // 触发预读第一项
    c_FileIter_InternalFetch(iter);
#endif

    return C_ERR_OK;
}

c_bool_t c_FileIter_HasNext(c_FileIter_t* iter) {
    return (iter != NULL) ? iter->has_next : C_FALSE;
}

void c_FileIter_Next(c_FileIter_t* iter) {
    if (iter && iter->has_next) {
        c_FileIter_InternalFetch(iter);
    }
}

const c_FileEntry_t* c_FileIter_Get(c_FileIter_t* iter) {
    if (iter && iter->has_next) {
        return &(iter->current);
    }
    return NULL;
}

c_err_t c_FileIter_Remove(c_FileIter_t* iter) {
    if (!iter || !iter->has_next) return C_ERR_FAIL;

    char full_path[512];
#ifdef _WIN32
    snprintf(full_path, sizeof(full_path), "%s\\%s", iter->base_path, iter->current.name);
#else
    snprintf(full_path, sizeof(full_path), "%s/%s", iter->base_path, iter->current.name);
#endif

    int res = -1;
    if (iter->current.type == C_FILE_TYPE_DIR) {
#ifdef _WIN32
        res = RemoveDirectory(full_path) ? 0 : -1;
#else
        res = rmdir(full_path);
#endif
    } else {
#ifdef _WIN32
        res = DeleteFile(full_path) ? 0 : -1;
#else
        res = unlink(full_path);
#endif
    }

    // 执行完物理删除后，提前释放当前迭代器的内部流句柄，防止调用者后续发生未知异常
    iter->has_next = C_FALSE;
    if (iter->internal_ctx) {
#ifdef _WIN32
        FindClose(((WinIterCtx*)iter->internal_ctx)->hFind);
#else
        closedir(((PosixIterCtx*)iter->internal_ctx)->dir);
#endif
        C_FREE(iter->internal_ctx);
        iter->internal_ctx = NULL;
    }

    return (res == 0) ? C_ERR_OK : C_ERR_FAIL;
}