// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// 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 <stdlib.h>
#include <assert.h>
#include <string.h>
#include <stdio.h>
#include <sys/lock.h>

#include "esp_attr.h"
#include "esp_flash_data_types.h"
#include "esp_spi_flash.h"
#include "esp_partition.h"
#include "esp_flash_encrypt.h"
#include "esp_log.h"


#ifndef NDEBUG
// Enable built-in checks in queue.h in debug builds
#define INVARIANTS
#endif
#include "rom/queue.h"


typedef struct partition_list_item_ {
    esp_partition_t info;
    SLIST_ENTRY(partition_list_item_) next;
} partition_list_item_t;

typedef struct esp_partition_iterator_opaque_ {
    esp_partition_type_t type;                  // requested type
    esp_partition_subtype_t subtype;               // requested subtype
    const char* label;                          // requested label (can be NULL)
    partition_list_item_t* next_item;     // next item to iterate to
    esp_partition_t* info;                // pointer to info (it is redundant, but makes code more readable)
} esp_partition_iterator_opaque_t;


static esp_partition_iterator_opaque_t* iterator_create(esp_partition_type_t type, esp_partition_subtype_t subtype, const char* label);
static esp_err_t load_partitions();


static SLIST_HEAD(partition_list_head_, partition_list_item_) s_partition_list =
        SLIST_HEAD_INITIALIZER(s_partition_list);
static _lock_t s_partition_list_lock;


esp_partition_iterator_t esp_partition_find(esp_partition_type_t type,
        esp_partition_subtype_t subtype, const char* label)
{
    if (SLIST_EMPTY(&s_partition_list)) {
        // only lock if list is empty (and check again after acquiring lock)
        _lock_acquire(&s_partition_list_lock);
        esp_err_t err = ESP_OK;
        if (SLIST_EMPTY(&s_partition_list)) {
            err = load_partitions();
        }
        _lock_release(&s_partition_list_lock);
        if (err != ESP_OK) {
            return NULL;
        }
    }
    // create an iterator pointing to the start of the list
    // (next item will be the first one)
    esp_partition_iterator_t it = iterator_create(type, subtype, label);
    // advance iterator to the next item which matches constraints
    it = esp_partition_next(it);
    // if nothing found, it == NULL and iterator has been released
    return it;
}

esp_partition_iterator_t esp_partition_next(esp_partition_iterator_t it)
{
    assert(it);
    // iterator reached the end of linked list?
    if (it->next_item == NULL) {
        esp_partition_iterator_release(it);
        return NULL;
    }
    _lock_acquire(&s_partition_list_lock);
    for (; it->next_item != NULL; it->next_item = SLIST_NEXT(it->next_item, next)) {
        esp_partition_t* p = &it->next_item->info;
        if (it->type != p->type) {
            continue;
        }
        if (it->subtype != 0xff && it->subtype != p->subtype) {
            continue;
        }
        if (it->label != NULL && strcmp(it->label, p->label) != 0) {
            continue;
        }
        // all constraints match, bail out
        break;
    }
    _lock_release(&s_partition_list_lock);
    if (it->next_item == NULL) {
        esp_partition_iterator_release(it);
        return NULL;
    }
    it->info = &it->next_item->info;
    it->next_item = SLIST_NEXT(it->next_item, next);
    return it;
}

const esp_partition_t* esp_partition_find_first(esp_partition_type_t type,
        esp_partition_subtype_t subtype, const char* label)
{
    esp_partition_iterator_t it = esp_partition_find(type, subtype, label);
    if (it == NULL) {
        return NULL;
    }
    const esp_partition_t* res = esp_partition_get(it);
    esp_partition_iterator_release(it);
    return res;
}

static esp_partition_iterator_opaque_t* iterator_create(esp_partition_type_t type,
        esp_partition_subtype_t subtype, const char* label)
{
    esp_partition_iterator_opaque_t* it =
            (esp_partition_iterator_opaque_t*) malloc(sizeof(esp_partition_iterator_opaque_t));
    it->type = type;
    it->subtype = subtype;
    it->label = label;
    it->next_item = SLIST_FIRST(&s_partition_list);
    it->info = NULL;
    return it;
}

// Create linked list of partition_list_item_t structures.
// This function is called only once, with s_partition_list_lock taken.
static esp_err_t load_partitions()
{
    const uint32_t* ptr;
    spi_flash_mmap_handle_t handle;
    // map 64kB block where partition table is located
    esp_err_t err = spi_flash_mmap(ESP_PARTITION_TABLE_ADDR & 0xffff0000,
            SPI_FLASH_SEC_SIZE, SPI_FLASH_MMAP_DATA, (const void**) &ptr, &handle);
    if (err != ESP_OK) {
        return err;
    }
    // calculate partition address within mmap-ed region
    const esp_partition_info_t* it = (const esp_partition_info_t*)
            (ptr + (ESP_PARTITION_TABLE_ADDR & 0xffff) / sizeof(*ptr));
    const esp_partition_info_t* end = it + SPI_FLASH_SEC_SIZE / sizeof(*it);
    // tail of the linked list of partitions
    partition_list_item_t* last = NULL;
    for (; it != end; ++it) {
        if (it->magic != ESP_PARTITION_MAGIC) {
            break;
        }
        // allocate new linked list item and populate it with data from partition table
        partition_list_item_t* item = (partition_list_item_t*) malloc(sizeof(partition_list_item_t));
        item->info.address = it->pos.offset;
        item->info.size = it->pos.size;
        item->info.type = it->type;
        item->info.subtype = it->subtype;
        item->info.encrypted = it->flags & PART_FLAG_ENCRYPTED;
        if (esp_flash_encryption_enabled() && (
                it->type == PART_TYPE_APP
                || (it->type == PART_TYPE_DATA && it->subtype == PART_SUBTYPE_DATA_OTA))) {
            /* If encryption is turned on, all app partitions and OTA data
               are always encrypted */
            item->info.encrypted = true;
        }

        // it->label may not be zero-terminated
        strncpy(item->info.label, (const char*) it->label, sizeof(it->label));
        item->info.label[sizeof(it->label)] = 0;
        // add it to the list
        if (last == NULL) {
            SLIST_INSERT_HEAD(&s_partition_list, item, next);
        } else {
            SLIST_INSERT_AFTER(last, item, next);
        }
        last = item;
    }
    spi_flash_munmap(handle);
    return ESP_OK;
}

void esp_partition_iterator_release(esp_partition_iterator_t iterator)
{
    // iterator == NULL is okay
    free(iterator);
}

const esp_partition_t* esp_partition_get(esp_partition_iterator_t iterator)
{
    assert(iterator != NULL);
    return iterator->info;
}

const esp_partition_t *esp_partition_verify(const esp_partition_t *partition)
{
    assert(partition != NULL);
    const char *label = (strlen(partition->label) > 0) ? partition->label : NULL;
    esp_partition_iterator_t it = esp_partition_find(partition->type,
                                                     partition->subtype,
                                                     label);
    while (it != NULL) {
        const esp_partition_t *p = esp_partition_get(it);
        /* Can't memcmp() whole structure here as padding contents may be different */
        if (p->address == partition->address
            && partition->size == p->size
            && partition->encrypted == p->encrypted) {
            esp_partition_iterator_release(it);
            return p;
        }
        it = esp_partition_next(it);
    }
    esp_partition_iterator_release(it);
    return NULL;
}

esp_err_t esp_partition_read(const esp_partition_t* partition,
        size_t src_offset, void* dst, size_t size)
{
    assert(partition != NULL);
    if (src_offset > partition->size) {
        return ESP_ERR_INVALID_ARG;
    }
    if (src_offset + size > partition->size) {
        return ESP_ERR_INVALID_SIZE;
    }

    if (!partition->encrypted) {
        return spi_flash_read(partition->address + src_offset, dst, size);
    } else {
        /* Encrypted partitions need to be read via a cache mapping */
        const void *buf;
        spi_flash_mmap_handle_t handle;
        esp_err_t err;

        err = esp_partition_mmap(partition, src_offset, size,
                                 SPI_FLASH_MMAP_DATA, &buf, &handle);
        if (err != ESP_OK) {
            return err;
        }
        memcpy(dst, buf, size);
        spi_flash_munmap(handle);
        return ESP_OK;
    }
}

esp_err_t esp_partition_write(const esp_partition_t* partition,
                             size_t dst_offset, const void* src, size_t size)
{
    assert(partition != NULL);
    if (dst_offset > partition->size) {
        return ESP_ERR_INVALID_ARG;
    }
    if (dst_offset + size > partition->size) {
        return ESP_ERR_INVALID_SIZE;
    }
    dst_offset = partition->address + dst_offset;
    if (partition->encrypted) {
        return spi_flash_write_encrypted(dst_offset, src, size);
    } else {
        return spi_flash_write(dst_offset, src, size);
    }
}

esp_err_t esp_partition_erase_range(const esp_partition_t* partition,
                                    size_t start_addr, size_t size)
{
    assert(partition != NULL);
    if (start_addr > partition->size) {
        return ESP_ERR_INVALID_ARG;
    }
    if (start_addr + size > partition->size) {
        return ESP_ERR_INVALID_SIZE;
    }
    if (size % SPI_FLASH_SEC_SIZE != 0) {
        return ESP_ERR_INVALID_SIZE;
    }
    if (start_addr % SPI_FLASH_SEC_SIZE != 0) {
        return ESP_ERR_INVALID_ARG;
    }
    return spi_flash_erase_range(partition->address + start_addr, size);

}

/*
 * Note: current implementation ignores the possibility of multiple regions in the same partition being
 * mapped. Reference counting and address space re-use is delegated to spi_flash_mmap.
 *
 * If this becomes a performance issue (i.e. if we need to map multiple regions within the partition),
 * we can add esp_partition_mmapv which will accept an array of offsets and sizes, and return array of
 * mmaped pointers, and a single handle for all these regions.
 */
esp_err_t esp_partition_mmap(const esp_partition_t* partition, uint32_t offset, uint32_t size,
                             spi_flash_mmap_memory_t memory,
                             const void** out_ptr, spi_flash_mmap_handle_t* out_handle)
{
    assert(partition != NULL);
    if (offset > partition->size) {
        return ESP_ERR_INVALID_ARG;
    }
    if (offset + size > partition->size) {
        return ESP_ERR_INVALID_SIZE;
    }
    size_t phys_addr = partition->address + offset;
    // offset within 64kB block
    size_t region_offset = phys_addr & 0xffff;
    size_t mmap_addr = phys_addr & 0xffff0000;
    esp_err_t rc = spi_flash_mmap(mmap_addr, size, memory, out_ptr, out_handle);
    // adjust returned pointer to point to the correct offset
    if (rc == ESP_OK) {
        *out_ptr = (void*) (((ptrdiff_t) *out_ptr) + region_offset);
    }
    return rc;
}
