/*
 * Copyright (C) 2017 BlueKitchen GmbH
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the copyright holders nor the names of
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BLUEKITCHEN
 * GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 */

#define BTSTACK_FILE__ "btstack_tlv_posix.c"

#include "btstack_tlv.h"
#include "btstack_tlv_posix.h"
#include "btstack_debug.h"
#include "btstack_util.h"
#include "btstack_debug.h"
#include "string.h"

#include <stdlib.h>
#include <string.h>


// Header:
// - Magic: 'BTstack'
// - Status:
//   - bits 765432: reserved
//	 - bits 10:     epoch

// Entries
// - Tag: 32 bit
// - Len: 32 bit
// - Value: Len in bytes

#define BTSTACK_TLV_HEADER_LEN 8

#define MAX_TLV_VALUE_SIZE 2048

static const char * btstack_tlv_header_magic = "BTstack";

#define DUMMY_SIZE 4
typedef struct tlv_entry {
	void   * next;
	uint32_t tag;
	uint32_t len;
	uint8_t  value[DUMMY_SIZE];	// dummy size
} tlv_entry_t;

// testing support
static bool btstack_tlv_posix_read_only = false;

static void btstack_tlv_posix_append_tag(btstack_tlv_posix_t * self, uint32_t tag, const uint8_t * data, uint32_t data_size){

	if (!self->file) return;

	log_info("append tag %04x, len %u", tag, data_size);

	uint8_t header[8];
	big_endian_store_32(header, 0, tag);
	big_endian_store_32(header, 4, data_size);
	size_t written_header = fwrite(header, 1, sizeof(header), self->file);
	if (written_header != sizeof(header)) return;
	if (data_size > 0) {
		size_t written_value = fwrite(data, 1, data_size, self->file);
		if (written_value != data_size) return;
	}
	fflush(self->file);
}

static tlv_entry_t * btstack_tlv_posix_find_entry(btstack_tlv_posix_t * self, uint32_t tag){
	btstack_linked_list_iterator_t it;
	btstack_linked_list_iterator_init(&it, &self->entry_list);
	while (btstack_linked_list_iterator_has_next(&it)){
		tlv_entry_t * entry = (tlv_entry_t*) btstack_linked_list_iterator_next(&it);
		if (entry->tag != tag) continue;
		return entry;
	}
	return NULL;
}

/**
 * Delete Tag
 * @param tag
 */
static void btstack_tlv_posix_delete_tag(void * context, uint32_t tag){
	btstack_tlv_posix_t * self = (btstack_tlv_posix_t *) context;
	btstack_linked_list_iterator_t it;
	btstack_linked_list_iterator_init(&it, &self->entry_list);
	while (btstack_linked_list_iterator_has_next(&it)){
		tlv_entry_t * entry = (tlv_entry_t*) btstack_linked_list_iterator_next(&it);
		if (entry->tag != tag) continue;
		btstack_linked_list_iterator_remove(&it);
		free(entry);
		btstack_tlv_posix_append_tag(self, tag, NULL, 0);
		return;
	}
}

/**
 * Get Value for Tag
 * @param tag
 * @param buffer
 * @param buffer_size
 * @returns size of value
 */
static int btstack_tlv_posix_get_tag(void * context, uint32_t tag, uint8_t * buffer, uint32_t buffer_size){
	btstack_tlv_posix_t * self = (btstack_tlv_posix_t *) context;
	tlv_entry_t * entry = btstack_tlv_posix_find_entry(self, tag);
	// not found
	if (!entry) return 0;
	// return len if buffer = NULL
	if (!buffer) return entry->len;
	// otherwise copy data into buffer
	uint16_t bytes_to_copy = btstack_min(buffer_size, entry->len);
	memcpy(buffer, &entry->value[0], bytes_to_copy);
	return bytes_to_copy;
}

/**
 * Store Tag 
 * @param tag
 * @param data
 * @param data_size
 */
static int btstack_tlv_posix_store_tag(void * context, uint32_t tag, const uint8_t * data, uint32_t data_size){
	btstack_tlv_posix_t * self = (btstack_tlv_posix_t *) context;

	// enforce arbitrary max value size
	btstack_assert(data_size <= MAX_TLV_VALUE_SIZE);

	// remove old entry
	tlv_entry_t * old_entry = btstack_tlv_posix_find_entry(self, tag);
	if (old_entry){
		btstack_linked_list_remove(&self->entry_list, (btstack_linked_item_t *) old_entry);
		free(old_entry);
	}

	// create new entry
	uint32_t entry_size = sizeof(tlv_entry_t) - DUMMY_SIZE + data_size;
	tlv_entry_t * new_entry = (tlv_entry_t *) malloc(entry_size);
	if (!new_entry) return 0;
	memset(new_entry, 0, entry_size);
	new_entry->tag = tag;
	new_entry->len = data_size;
	memcpy(&new_entry->value[0], data, data_size);

	// append new entry
	btstack_linked_list_add(&self->entry_list, (btstack_linked_item_t *) new_entry);

	// write new tag
	btstack_tlv_posix_append_tag(self, tag, data, data_size);

	return 0;
}

// returns 0 on success
static int btstack_tlv_posix_read_db(btstack_tlv_posix_t * self){
	// open file
	log_info("open db %s", self->db_path);
    const char * mode = btstack_tlv_posix_read_only ? "r" : "r+";
    self->file = fopen(self->db_path, mode);
    uint8_t header[BTSTACK_TLV_HEADER_LEN];
    if (self->file){
    	// checker header
	    size_t objects_read = fread(header, 1, BTSTACK_TLV_HEADER_LEN, self->file );
	    int file_valid = 0;
	    if (objects_read == BTSTACK_TLV_HEADER_LEN){
	    	if (memcmp(header, btstack_tlv_header_magic, strlen(btstack_tlv_header_magic)) == 0){
		    	log_info("BTstack Magic Header found");
		    	// read entries
		    	while (true){
					uint8_t entry[8];
					size_t 	entries_read = fread(entry, 1, sizeof(entry), self->file);
					if (entries_read == 0){
						// EOF, we're good
						file_valid = 1;
						break;
					}
					if (entries_read != sizeof(entry)) break;

                    uint32_t tag = big_endian_read_32(entry, 0);
                    uint32_t len = big_endian_read_32(entry, 4);

                    // arbitrary safety check: values <= MAX_TLV_VALUE_SIZE
                    if (len > MAX_TLV_VALUE_SIZE) break;

                    // create new entry for regular tag
                    tlv_entry_t * new_entry = NULL;
                    if (len > 0) {
                        new_entry = (tlv_entry_t *) malloc(sizeof(tlv_entry_t) - DUMMY_SIZE + len);
                        if (!new_entry) return 0;
                        new_entry->tag = tag;
                        new_entry->len = len;

                        // read
                        size_t value_read = fread(&new_entry->value[0], 1, len, self->file);
                        if (value_read != len) break;
                    }

                    // remove old entry
                    tlv_entry_t * old_entry = btstack_tlv_posix_find_entry(self, tag);
                    if (old_entry){
                        btstack_linked_list_remove(&self->entry_list, (btstack_linked_item_t *) old_entry);
                        free(old_entry);
                    }

                    // append new entry
                    if (new_entry){
	                    btstack_linked_list_add(&self->entry_list, (btstack_linked_item_t *) new_entry);
                    }
		    	}
	    	}
	    }
	    if (!file_valid) {
	    	log_info("file invalid, re-create");
    		fclose(self->file);
    		self->file = NULL;
	    }
    }

    // close file in read-only mode
    if (btstack_tlv_posix_read_only && (self->file != NULL)){
        fclose(self->file);
        self->file = NULL;
        return 0;
    }

    if (!self->file){
    	// create truncate file
	    self->file = fopen(self->db_path,"w+");
        if (!self->file) {
            log_error("failed to create file");
            return -1;
        }
	    memset(header, 0, sizeof(header));
	    strcpy((char *)header, btstack_tlv_header_magic);
	    fwrite(header, 1, sizeof(header), self->file);
	    // write out all valid entries (if any)
		btstack_linked_list_iterator_t it;
		btstack_linked_list_iterator_init(&it, &self->entry_list);
		while (btstack_linked_list_iterator_has_next(&it)){
			tlv_entry_t * entry = (tlv_entry_t*) btstack_linked_list_iterator_next(&it);
			btstack_tlv_posix_append_tag(self, entry->tag, &entry->value[0], entry->len);
		}
    }
	return 0;
}

static const btstack_tlv_t btstack_tlv_posix = {
	/* int  (*get_tag)(..);     */ &btstack_tlv_posix_get_tag,
	/* int (*store_tag)(..);    */ &btstack_tlv_posix_store_tag,
	/* void (*delete_tag)(v..); */ &btstack_tlv_posix_delete_tag,
};

/**
 * Init Tag Length Value Store
 */
const btstack_tlv_t * btstack_tlv_posix_init_instance(btstack_tlv_posix_t * self, const char * db_path){
	memset(self, 0, sizeof(btstack_tlv_posix_t));
	self->db_path = db_path;

	// read DB
    if (db_path != NULL){
        btstack_tlv_posix_read_db(self);
    }
	return &btstack_tlv_posix;
}

void btstack_tlv_posix_set_read_only(void){
    btstack_tlv_posix_read_only = true;
}

/**
 * Free TLV entries
 * @param self
 */
void btstack_tlv_posix_deinit(btstack_tlv_posix_t * self){
    // free all entries
    btstack_linked_list_iterator_t it;
    btstack_linked_list_iterator_init(&it, &self->entry_list);
    while (btstack_linked_list_iterator_has_next(&it)){
        tlv_entry_t * entry = (tlv_entry_t*) btstack_linked_list_iterator_next(&it);
		btstack_linked_list_iterator_remove(&it);
		free(entry);
    }
    btstack_tlv_posix_read_only = true;
}