/* mbed Microcontroller Library
 * Copyright (c) 2018 ARM Limited
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "FileSystemStore.h"
#include "Dir.h"
#include "File.h"
#include "BlockDevice.h"
#include "mbed_error.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#include "mbed_trace.h"
#define TRACE_GROUP "FSST"

#define FSST_REVISION 1
#define FSST_MAGIC 0x46535354 // "FSST" hex 'magic' signature

#ifndef FSST_FOLDER_PATH
#define FSST_FOLDER_PATH "kvstore" //default FileSystemStore folder path on fs
#endif

static const uint32_t supported_flags = mbed::KVStore::WRITE_ONCE_FLAG;

using namespace mbed;

// incremental set handle
typedef struct {
    char *key;
    uint32_t create_flags;
    size_t data_size;
    File *file_handle;
} inc_set_handle_t;

// iterator handle
typedef struct {
    void *dir_handle;
    char *prefix;
} key_iterator_handle_t;

// Local Functions
static char *string_ndup(const char *src, size_t size);


// Class Functions
FileSystemStore::FileSystemStore(FileSystem *fs) : _fs(fs),
    _is_initialized(false)
{

}

int FileSystemStore::init()
{
    int status = MBED_SUCCESS;

    _mutex.lock();

    _cfg_fs_path_size = strlen(FSST_FOLDER_PATH);
    _cfg_fs_path = string_ndup(FSST_FOLDER_PATH, _cfg_fs_path_size);
    _full_path_key = new char[_cfg_fs_path_size + KVStore::MAX_KEY_SIZE + 1];
    memset(_full_path_key, 0, (_cfg_fs_path_size + KVStore::MAX_KEY_SIZE + 1));
    strncpy(_full_path_key, _cfg_fs_path, _cfg_fs_path_size);
    _full_path_key[_cfg_fs_path_size] = '/';
    _cur_inc_data_size = 0;
    _cur_inc_set_handle = NULL;
    Dir kv_dir;

    if (kv_dir.open(_fs, _cfg_fs_path) != 0) {
        tr_info("KV Dir: %s, doesnt exist - creating new.. ", _cfg_fs_path); //TBD verify ERRNO NOEXIST
        if (_fs->mkdir(_cfg_fs_path,/* which flags ? */0777) != 0) {
            tr_error("KV Dir: %s, mkdir failed.. ", _cfg_fs_path); //TBD verify ERRNO NOEXIST
            status = MBED_ERROR_FAILED_OPERATION ;
            goto exit_point;
        }
    } else {
        tr_info("KV Dir: %s, exists(verified) - now closing it", _cfg_fs_path);
        if (kv_dir.close() != 0) {
            tr_error("KV Dir: %s, dir_close failed", _cfg_fs_path); //TBD verify ERRNO NOEXIST
        }
    }

    _is_initialized = true;
exit_point:

    _mutex.unlock();

    return status;

}

int FileSystemStore::deinit()
{
    _mutex.lock();
    _is_initialized = false;
    delete[] _cfg_fs_path;
    delete[] _full_path_key;
    _mutex.unlock();
    return MBED_SUCCESS;

}

int FileSystemStore::reset()
{
    int status = MBED_SUCCESS;
    Dir kv_dir;
    struct dirent dir_ent;

    _mutex.lock();
    if (false == _is_initialized) {
        status = MBED_ERROR_NOT_READY;
        goto exit_point;
    }

    kv_dir.open(_fs, _cfg_fs_path);

    while (kv_dir.read(&dir_ent) != 0) {
        tr_info("Looping FSST folder: %s, File - %s", _cfg_fs_path, dir_ent.d_name);
        if (dir_ent.d_type != DT_REG) {
            tr_error("KV_Dir should contain only Regular File - %s", dir_ent.d_name);
            continue;
        }
        // Build File's full path name and delete it (even if write-onced)
        _build_full_path_key(dir_ent.d_name);
        _fs->remove(_full_path_key);
    }

    kv_dir.close();

exit_point:
    _mutex.unlock();
    return status;
}

int FileSystemStore::set(const char *key, const void *buffer, size_t size, uint32_t create_flags)
{
    int status = MBED_SUCCESS;
    set_handle_t handle;

    if (false == _is_initialized) {
        status = MBED_ERROR_NOT_READY;
        goto exit_point;
    }

    if ((!is_valid_key(key)) || ((buffer == NULL) && (size > 0))) {
        status = MBED_ERROR_INVALID_ARGUMENT;
        goto exit_point;
    }

    status = set_start(&handle, key, size, create_flags);
    if (status != MBED_SUCCESS) {
        tr_error("FSST Set set_start Failed: %d", status);
        goto exit_point;
    }

    status = set_add_data(handle, buffer, size);
    if (status != MBED_SUCCESS) {
        tr_error("FSST Set set_add_data Failed: %d", status);
        set_finalize(handle);
        goto exit_point;
    }

    status = set_finalize(handle);
    if (status != MBED_SUCCESS) {
        tr_error("FSST Set set_finalize Failed: %d", status);
        goto exit_point;
    }

exit_point:

    return status;
}

int FileSystemStore::get(const char *key, void *buffer, size_t buffer_size, size_t *actual_size, size_t offset)
{
    int status = MBED_SUCCESS;

    File kv_file;
    size_t kv_file_size = 0;
    size_t value_actual_size = 0;

    _mutex.lock();

    if (false == _is_initialized) {
        status = MBED_ERROR_NOT_READY;
        goto exit_point;
    }

    key_metadata_t key_metadata;

    if ((status = _verify_key_file(key, &key_metadata, &kv_file)) != MBED_SUCCESS) {
        tr_error("File Verification failed, status: %d", status);
        goto exit_point;
    }

    kv_file_size = kv_file.size() - key_metadata.metadata_size;
    // Actual size is the minimum of buffer_size and remainder of data in file (file's data size - offset)
    value_actual_size = buffer_size;
    if (offset > kv_file_size) {
        status = MBED_ERROR_INVALID_SIZE;
        goto exit_point;
    } else if ((kv_file_size - offset) < buffer_size) {
        value_actual_size = kv_file_size - offset;
    }

    if ((buffer == NULL) && (value_actual_size > 0)) {
        status = MBED_ERROR_INVALID_DATA_DETECTED;
        goto exit_point;
    }

    if (actual_size != NULL) {
        *actual_size = value_actual_size;
    }

    kv_file.seek(key_metadata.metadata_size + offset, SEEK_SET);
    // Read remainder of data
    kv_file.read(buffer, value_actual_size);

exit_point:
    if ((status == MBED_SUCCESS) ||
            (status == MBED_ERROR_INVALID_DATA_DETECTED)) {
        kv_file.close();
    }
    _mutex.unlock();

    return status;
}

int FileSystemStore::get_info(const char *key, info_t *info)
{
    int status = MBED_SUCCESS;
    File kv_file;

    _mutex.lock();

    if (false == _is_initialized) {
        status = MBED_ERROR_NOT_READY;
        goto exit_point;
    }

    key_metadata_t key_metadata;

    if ((status = _verify_key_file(key, &key_metadata, &kv_file)) != MBED_SUCCESS) {
        tr_error("File Verification failed, status: %d", status);
        goto exit_point;
    }

    if (info != NULL) {
        info->size = kv_file.size() - key_metadata.metadata_size;
        info->flags = key_metadata.user_flags;
    }

exit_point:
    if ((status == MBED_SUCCESS) ||
            (status == MBED_ERROR_INVALID_DATA_DETECTED)) {
        kv_file.close();
    }
    _mutex.unlock();

    return status;
}

int FileSystemStore::remove(const char *key)
{
    File kv_file;
    key_metadata_t key_metadata;

    _mutex.lock();

    int status = MBED_SUCCESS;

    if (false == _is_initialized) {
        status = MBED_ERROR_NOT_READY;
        goto exit_point;
    }

    /* If File Exists and is Valid, then check its Write Once Flag to verify its disabled before removing */
    /* If File exists and is not valid, or is Valid and not Write-Onced then remove it */
    if ((status = _verify_key_file(key, &key_metadata, &kv_file)) == MBED_SUCCESS) {
        tr_error("File: %s, Exists Verifying Write Once Disabled before setting new value", _full_path_key);
        if (key_metadata.user_flags & KVStore::WRITE_ONCE_FLAG) {
            kv_file.close();
            status = MBED_ERROR_WRITE_PROTECTED;
            goto exit_point;
        }
    } else if ((status == MBED_ERROR_ITEM_NOT_FOUND) ||
               (status == MBED_ERROR_INVALID_ARGUMENT)) {
        goto exit_point;
    }
    kv_file.close();

    if (0 != _fs->remove(_full_path_key)) {
        status =  MBED_ERROR_FAILED_OPERATION;
    }

exit_point:
    _mutex.unlock();
    return status;
}

// Incremental set API
int FileSystemStore::set_start(set_handle_t *handle, const char *key, size_t final_data_size, uint32_t create_flags)
{
    int status = MBED_SUCCESS;
    inc_set_handle_t *set_handle = NULL;
    File *kv_file;
    key_metadata_t key_metadata;
    int key_len = 0;

    if (create_flags & ~supported_flags) {
        return MBED_ERROR_INVALID_ARGUMENT;
    }

    // Only a single key file can be incrementaly editted at a time
    _mutex.lock();

    kv_file = new File;

    if (handle == NULL) {
        status = MBED_ERROR_INVALID_ARGUMENT;
        goto exit_point;
    }

    /* If File Exists and is Valid, then check its Write Once Flag to verify its disabled before setting */
    /* If File exists and is not valid, or is Valid and not Write-Onced then erase it */
    status = _verify_key_file(key, &key_metadata, kv_file);

    if (status == MBED_ERROR_INVALID_ARGUMENT) {
        tr_error("File Verification failed, status: %d", status);
        goto exit_point;
    }

    if (status == MBED_SUCCESS) {
        tr_info("File: %s, Exists. Verifying Write Once Disabled before setting new value", _full_path_key);
        if (key_metadata.user_flags & KVStore::WRITE_ONCE_FLAG) {
            kv_file->close();
            status = MBED_ERROR_WRITE_PROTECTED;
            goto exit_point;
        }
    }

    /* For Success (not write_once) and for corrupted data close file before recreating it as a new file */
    if (status != MBED_ERROR_ITEM_NOT_FOUND) {
        kv_file->close();
    }

    if ((status = kv_file->open(_fs, _full_path_key, O_WRONLY | O_CREAT | O_TRUNC)) != MBED_SUCCESS) {
        tr_info("set_start failed to open: %s, for writing, err: %d", _full_path_key, status);
        status = MBED_ERROR_FAILED_OPERATION ;
        goto exit_point;
    }
    _cur_inc_data_size = 0;

    set_handle = new inc_set_handle_t;
    set_handle->create_flags = create_flags;
    set_handle->data_size = final_data_size;
    set_handle->file_handle = kv_file;
    key_len = strlen(key);
    set_handle->key = string_ndup(key, key_len);
    *handle = (set_handle_t)set_handle;
    _cur_inc_set_handle = *handle;

    key_metadata.magic = FSST_MAGIC;
    key_metadata.metadata_size = sizeof(key_metadata_t);
    key_metadata.revision = FSST_REVISION;
    key_metadata.user_flags = create_flags;
    kv_file->write(&key_metadata, sizeof(key_metadata_t));

exit_point:
    if (status != MBED_SUCCESS) {
        delete kv_file;
        _mutex.unlock();
    }
    return status;
}

int FileSystemStore::set_add_data(set_handle_t handle, const void *value_data, size_t data_size)
{
    int status = MBED_SUCCESS;
    size_t added_data = 0;
    inc_set_handle_t *set_handle = (inc_set_handle_t *)handle;
    File *kv_file;

    if (((value_data == NULL) && (data_size > 0)) || (handle == NULL) || (handle != _cur_inc_set_handle)) {
        status = MBED_ERROR_INVALID_ARGUMENT;
        goto exit_point;
    }

    // Single key incrementally edited, can be edited from multiple threads - lock to protect
    _inc_data_add_mutex.lock();
    if ((_cur_inc_data_size + data_size) > set_handle->data_size) {
        tr_warning("Added Data(%d) will exceed set_start final size(%d) - not adding data to file: %s",
                   _cur_inc_data_size + data_size, set_handle->data_size, _full_path_key);
        status = MBED_ERROR_INVALID_SIZE;
        goto exit_point;
    }

    kv_file = set_handle->file_handle;

    added_data = kv_file->write(value_data, data_size);
    if (added_data != data_size) {
        status = MBED_ERROR_FAILED_OPERATION ;
    }
    _cur_inc_data_size += added_data;

exit_point:
    if (status != MBED_ERROR_INVALID_ARGUMENT) {
        _inc_data_add_mutex.unlock();
    }

    return status;
}

int FileSystemStore::set_finalize(set_handle_t handle)
{
    int status = MBED_SUCCESS;
    inc_set_handle_t *set_handle = NULL;

    if ((handle == NULL) || (handle != _cur_inc_set_handle)) {
        status =  MBED_ERROR_INVALID_ARGUMENT;
        goto exit_point;
    }

    set_handle = (inc_set_handle_t *)handle;

    if (set_handle->key == NULL) {
        status = MBED_ERROR_INVALID_DATA_DETECTED;
    } else {
        if (_cur_inc_data_size != set_handle->data_size) {
            tr_error("Accumulated Data (%d) size doesn't match set_start final size (%d) - file: %s", _cur_inc_data_size,
                     set_handle->data_size, _full_path_key);
            status = MBED_ERROR_INVALID_SIZE;
            _fs->remove(_full_path_key);
        }
        delete[] set_handle->key;
    }

    set_handle->file_handle->close();
    delete set_handle->file_handle;
    delete set_handle;
    _cur_inc_data_size = 0;
    _cur_inc_set_handle = NULL;

exit_point:
    if (status != MBED_ERROR_INVALID_ARGUMENT) {
        _mutex.unlock();
    }

    return status;
}

int FileSystemStore::iterator_open(iterator_t *it, const char *prefix)
{
    int status = MBED_SUCCESS;
    Dir *kv_dir = NULL;
    key_iterator_handle_t *key_it = NULL;

    if (it == NULL) {
        return MBED_ERROR_INVALID_ARGUMENT;
    }

    _mutex.lock();
    if (false == _is_initialized) {
        status = MBED_ERROR_NOT_READY;
        goto exit_point;
    }
    key_it = new key_iterator_handle_t;
    key_it->dir_handle = NULL;
    key_it->prefix = NULL;
    if (prefix != NULL) {
        key_it->prefix = string_ndup(prefix, KVStore::MAX_KEY_SIZE);
    }

    kv_dir = new Dir;
    if (kv_dir->open(_fs, _cfg_fs_path) != 0) {
        tr_error("KV Dir: %s, doesnt exist", _cfg_fs_path); //TBD verify ERRNO NOEXIST
        delete kv_dir;
        if (key_it->prefix != NULL) {
            delete[] key_it->prefix;
        }
        delete key_it;
        status = MBED_ERROR_ITEM_NOT_FOUND;
        goto exit_point;
    }

    key_it->dir_handle = kv_dir;

    *it = (iterator_t)key_it;

exit_point:
    _mutex.unlock();

    return status;
}

int FileSystemStore::iterator_next(iterator_t it, char *key, size_t key_size)
{
    Dir *kv_dir;
    struct dirent kv_dir_ent;
    int status = MBED_ERROR_ITEM_NOT_FOUND;
    key_iterator_handle_t *key_it = NULL;
    size_t key_name_size = KVStore::MAX_KEY_SIZE;
    if (key_size < key_name_size) {
        key_name_size = key_size;
    }

    _mutex.lock();
    if (false == _is_initialized) {
        status = MBED_ERROR_NOT_READY;
        goto exit_point;
    }

    key_it = (key_iterator_handle_t *)it;

    if (key_name_size < strlen(key_it->prefix)) {
        status = MBED_ERROR_INVALID_SIZE;
        goto exit_point;
    }

    kv_dir = (Dir *)key_it->dir_handle;

    while (kv_dir->read(&kv_dir_ent) != 0) {
        if (kv_dir_ent.d_type != DT_REG) {
            tr_error("KV_Dir should contain only Regular File - %s", kv_dir_ent.d_name);
            continue;
        }

        if ((key_it->prefix == NULL) ||
                (strncmp(kv_dir_ent.d_name, key_it->prefix, strlen(key_it->prefix)) == 0)) {
            if (key_name_size < strlen(kv_dir_ent.d_name)) {
                status = MBED_ERROR_INVALID_SIZE;
                break;
            }
            strncpy(key, kv_dir_ent.d_name, key_name_size);
            key[key_name_size - 1] = '\0';
            status = MBED_SUCCESS;
            break;
        }
    }

exit_point:
    _mutex.unlock();
    return status;
}

int FileSystemStore::iterator_close(iterator_t it)
{
    int status = MBED_SUCCESS;
    key_iterator_handle_t *key_it = (key_iterator_handle_t *)it;

    _mutex.lock();
    if (key_it == NULL) {
        status = MBED_ERROR_INVALID_ARGUMENT;
        goto exit_point;
    }

    if (key_it->prefix != NULL) {
        delete[] key_it->prefix;
    }

    ((Dir *)(key_it->dir_handle))->close();

    if (key_it->dir_handle != NULL) {
        delete ((Dir *)(key_it->dir_handle));
    }
    delete key_it;

exit_point:
    _mutex.unlock();
    return status;
}

int FileSystemStore::_verify_key_file(const char *key, key_metadata_t *key_metadata, File *kv_file)
{
    int status = MBED_SUCCESS;

    if (!is_valid_key(key)) {
        status = MBED_ERROR_INVALID_ARGUMENT;
        goto exit_point;
    }

    _build_full_path_key(key);

    if (0 != kv_file->open(_fs, _full_path_key, O_RDONLY)) {
        tr_info("Couldn't read: %s", _full_path_key);
        status = MBED_ERROR_ITEM_NOT_FOUND;
        goto exit_point;
    }

    //Read Metadata
    kv_file->read(key_metadata, sizeof(key_metadata_t));

    if ((key_metadata->magic != FSST_MAGIC) ||
            (key_metadata->revision > FSST_REVISION)) {
        status = MBED_ERROR_INVALID_DATA_DETECTED;
        goto exit_point;
    }

exit_point:
    return status;
}

int FileSystemStore::_build_full_path_key(const char *key_src)
{
    strncpy(&_full_path_key[_cfg_fs_path_size + 1/* for path's \ */], key_src, KVStore::MAX_KEY_SIZE);
    _full_path_key[(_cfg_fs_path_size + KVStore::MAX_KEY_SIZE)] = '\0';
    return 0;
}

// Local Functions
static char *string_ndup(const char *src, size_t size)
{
    char *string_copy = new char[size + 1];
    strncpy(string_copy, src, size);
    string_copy[size] = '\0';
    return string_copy;
}