/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

#define LOG_MODULE_NAME mcumgr_flash_mgmt
#define LOG_LEVEL CONFIG_IMG_MANAGER_LOG_LEVEL
#include <logging/log.h>
LOG_MODULE_REGISTER(LOG_MODULE_NAME);

#include <assert.h>
#include <drivers/flash.h>
#include <storage/flash_map.h>
#include <zephyr.h>
#include <soc.h>
#include <init.h>
#include <dfu/mcuboot.h>
#include <dfu/flash_img.h>
#include <mgmt/mgmt.h>
#include <img_mgmt/img_mgmt_impl.h>
#include <img_mgmt/img_mgmt.h>
#include <img_mgmt/image.h>
#include "../../../src/img_mgmt_priv.h"

/**
 * Determines if the specified area of flash is completely unwritten.
 */
static int
zephyr_img_mgmt_flash_check_empty(uint8_t fa_id, bool *out_empty)
{
    const struct flash_area *fa;
    uint32_t data[16];
    off_t addr;
    off_t end;
    int bytes_to_read;
    int rc;
    int i;

    rc = flash_area_open(fa_id, &fa);
    if (rc != 0) {
        return MGMT_ERR_EUNKNOWN;
    }

    assert(fa->fa_size % 4 == 0);

    end = fa->fa_size;
    for (addr = 0; addr < end; addr += sizeof data) {
        if (end - addr < sizeof data) {
            bytes_to_read = end - addr;
        } else {
            bytes_to_read = sizeof data;
        }

        rc = flash_area_read(fa, addr, data, bytes_to_read);
        if (rc != 0) {
            flash_area_close(fa);
            return MGMT_ERR_EUNKNOWN;
        }

        for (i = 0; i < bytes_to_read / 4; i++) {
            if (data[i] != 0xffffffff) {
                *out_empty = false;
                flash_area_close(fa);
                return 0;
            }
        }
    }

    *out_empty = true;
    flash_area_close(fa);
    return 0;
}

/**
 * Get flash_area ID for a image slot number.
 */
static uint8_t
zephyr_img_mgmt_flash_area_id(int slot)
{
    uint8_t fa_id;

    switch (slot) {
    case 0:
        fa_id = FLASH_AREA_ID(image_0);
        break;

    case 1:
        fa_id = FLASH_AREA_ID(image_1);
        break;

    default:
        assert(0);
        fa_id = FLASH_AREA_ID(image_1);
        break;
    }

    return fa_id;
}

static int
img_mgmt_find_best_area_id(void)
{
    struct image_version ver;
    int best = -1;
    int i;
    int rc;

    for (i = 0; i < 2; i++) {
        rc = img_mgmt_read_info(i, &ver, NULL, NULL);
        if (rc < 0) {
            continue;
        }
        if (rc == 0) {
            /* Image in slot is ok. */
            if (img_mgmt_slot_in_use(i)) {
                /* Slot is in use; can't use this. */
                continue;
            } else {
                /*
                 * Not active slot, but image is ok. Use it if there are
                 * no better candidates.
                 */
                best = i;
            }
            continue;
        }
        best = i;
        break;
    }
    if (best >= 0) {
        best = zephyr_img_mgmt_flash_area_id(best);
    }
    return best;
}

/**
 * Compares two image version numbers in a semver-compatible way.
 *
 * @param a                     The first version to compare.
 * @param b                     The second version to compare.
 *
 * @return                      -1 if a < b
 * @return                       0 if a = b
 * @return                       1 if a > b
 */
static int
img_mgmt_vercmp(const struct image_version *a, const struct image_version *b)
{
    if (a->iv_major < b->iv_major) {
        return -1;
    } else if (a->iv_major > b->iv_major) {
        return 1;
    }

    if (a->iv_minor < b->iv_minor) {
        return -1;
    } else if (a->iv_minor > b->iv_minor) {
        return 1;
    }

    if (a->iv_revision < b->iv_revision) {
        return -1;
    } else if (a->iv_revision > b->iv_revision) {
        return 1;
    }

    /* Note: For semver compatibility, don't compare the 32-bit build num. */

    return 0;
}

int
img_mgmt_impl_erase_slot(void)
{
    bool empty;
    int rc;

    rc = zephyr_img_mgmt_flash_check_empty(FLASH_AREA_ID(image_1),
                                           &empty);
    if (rc != 0) {
        return MGMT_ERR_EUNKNOWN;
    }

    if (!empty) {
        rc = boot_erase_img_bank(FLASH_AREA_ID(image_1));
        if (rc != 0) {
            return MGMT_ERR_EUNKNOWN;
        }
    }

    return 0;
}

int
img_mgmt_impl_write_pending(int slot, bool permanent)
{
    int rc;

    if (slot != 1) {
        return MGMT_ERR_EINVAL;
    }

    rc = boot_request_upgrade(permanent);
    if (rc != 0) {
        return MGMT_ERR_EUNKNOWN;
    }

    return 0;
}

int
img_mgmt_impl_write_confirmed(void)
{
    int rc;

    rc = boot_write_img_confirmed();
    if (rc != 0) {
        return MGMT_ERR_EUNKNOWN;
    }

    return 0;
}

int
img_mgmt_impl_read(int slot, unsigned int offset, void *dst,
                   unsigned int num_bytes)
{
    const struct flash_area *fa;
    int rc;

    rc = flash_area_open(zephyr_img_mgmt_flash_area_id(slot), &fa);
    if (rc != 0) {
      return MGMT_ERR_EUNKNOWN;
    }

    rc = flash_area_read(fa, offset, dst, num_bytes);
    flash_area_close(fa);

    if (rc != 0) {
      return MGMT_ERR_EUNKNOWN;
    }

    return 0;
}

int
img_mgmt_impl_write_image_data(unsigned int offset, const void *data,
                               unsigned int num_bytes, bool last)
{
	int rc;
#if (CONFIG_HEAP_MEM_POOL_SIZE > 0)
	static struct flash_img_context *ctx = NULL;
#else
	static struct flash_img_context ctx_data;
#define ctx (&ctx_data)
#endif

#if (CONFIG_HEAP_MEM_POOL_SIZE > 0)
	if (offset != 0 && ctx == NULL) {
		return MGMT_ERR_EUNKNOWN;
	}
#endif

	if (offset == 0) {
#if (CONFIG_HEAP_MEM_POOL_SIZE > 0)
		if (ctx == NULL) {
			ctx = k_malloc(sizeof(*ctx));

			if (ctx == NULL) {
				return MGMT_ERR_ENOMEM;
			}
		}
#endif
		rc = flash_img_init(ctx);

		if (rc != 0) {
			return MGMT_ERR_EUNKNOWN;
		}
	}

	if (offset != ctx->stream.bytes_written + ctx->stream.buf_bytes) {
		return MGMT_ERR_EUNKNOWN;
	}

	/* Cast away const. */
	rc = flash_img_buffered_write(ctx, (void *)data, num_bytes, last);
	if (rc != 0) {
		return MGMT_ERR_EUNKNOWN;
	}

#if (CONFIG_HEAP_MEM_POOL_SIZE > 0)
	if (last) {
		k_free(ctx);
		ctx = NULL;
	}
#endif

	return 0;
}

int
img_mgmt_impl_erase_image_data(unsigned int off, unsigned int num_bytes)
{
    const struct flash_area *fa;
    int rc;

    if (off != 0) {
        rc = MGMT_ERR_EINVAL;
        goto end;
    }

    rc = flash_area_open(FLASH_AREA_ID(image_1), &fa);
    if (rc != 0) {
        LOG_ERR("Can't bind to the flash area (err %d)", rc);
        rc = MGMT_ERR_EUNKNOWN;
        goto end;
    }

    /* align requested erase size to the erase-block-size */
    struct device *dev = flash_area_get_device(fa);
    struct flash_pages_info page;
    off_t page_offset = fa->fa_off + num_bytes - 1;

    rc = flash_get_page_info_by_offs(dev, page_offset, &page);
    if (rc != 0) {
        LOG_ERR("bad offset (0x%lx)", (long)page_offset);
        rc = MGMT_ERR_EUNKNOWN;
        goto end_fa;
    }

    size_t erase_size = page.start_offset + page.size - fa->fa_off;
    
    rc = flash_area_erase(fa, 0, erase_size);

    if (rc != 0) {
        LOG_ERR("image slot erase of 0x%zx bytes failed (err %d)", erase_size,
                rc);
        rc = MGMT_ERR_EUNKNOWN;
        goto end_fa;
    }

    LOG_INF("Erased 0x%zx bytes of image slot", erase_size);

    /* erase the image trailer area if it was not erased */
    off = BOOT_TRAILER_IMG_STATUS_OFFS(fa);
    if (off >= erase_size) {
        rc = flash_get_page_info_by_offs(dev, fa->fa_off + off, &page);

        off = page.start_offset - fa->fa_off;
        erase_size = fa->fa_size - off;

        rc = flash_area_erase(fa, off, erase_size);
        if (rc != 0) {
            LOG_ERR("image slot trailer erase of 0x%zx bytes failed (err %d)",
                    erase_size, rc);
            rc = MGMT_ERR_EUNKNOWN;
            goto end_fa;
        }

        LOG_INF("Erased 0x%zx bytes of image slot trailer", erase_size);
    }

    rc = 0;

end_fa:
    flash_area_close(fa);
end:
    return rc;
}

#if IMG_MGMT_LAZY_ERASE
int img_mgmt_impl_erase_if_needed(uint32_t off, uint32_t len)
{
    /* This is done internally to the flash_img API. */
    return 0;
}
#endif

int
img_mgmt_impl_swap_type(void)
{
    switch (mcuboot_swap_type()) {
    case BOOT_SWAP_TYPE_NONE:
        return IMG_MGMT_SWAP_TYPE_NONE;
    case BOOT_SWAP_TYPE_TEST:
        return IMG_MGMT_SWAP_TYPE_TEST;
    case BOOT_SWAP_TYPE_PERM:
        return IMG_MGMT_SWAP_TYPE_PERM;
    case BOOT_SWAP_TYPE_REVERT:
        return IMG_MGMT_SWAP_TYPE_REVERT;
    default:
        assert(0);
        return IMG_MGMT_SWAP_TYPE_NONE;
    }
}

/**
 * Verifies an upload request and indicates the actions that should be taken
 * during processing of the request.  This is a "read only" function in the
 * sense that it doesn't write anything to flash and doesn't modify any global
 * variables.
 *
 * @param req                   The upload request to inspect.
 * @param action                On success, gets populated with information
 *                                  about how to process the request.
 *
 * @return                      0 if processing should occur;
 *                              A MGMT_ERR code if an error response should be
 *                                  sent instead.
 */
int
img_mgmt_impl_upload_inspect(const struct img_mgmt_upload_req *req,
                             struct img_mgmt_upload_action *action,
                             const char **errstr)
{
    const struct image_header *hdr;
    const struct flash_area *fa;
    struct image_version cur_ver;
    uint8_t rem_bytes;
    bool empty;
    int rc;

    memset(action, 0, sizeof *action);

    if (req->off == -1) {
        /* Request did not include an `off` field. */
        *errstr = img_mgmt_err_str_hdr_malformed;
        return MGMT_ERR_EINVAL;
    }

    if (req->off == 0) {
        /* First upload chunk. */
        if (req->data_len < sizeof(struct image_header)) {
            /*
             * Image header is the first thing in the image.
             */
            *errstr = img_mgmt_err_str_hdr_malformed;
            return MGMT_ERR_EINVAL;
        }

        if (req->size == -1) {
            /* Request did not include a `len` field. */
            *errstr = img_mgmt_err_str_hdr_malformed;
            return MGMT_ERR_EINVAL;
        }
        action->size = req->size;

        hdr = (struct image_header *)req->img_data;
        if (hdr->ih_magic != IMAGE_MAGIC) {
            *errstr = img_mgmt_err_str_magic_mismatch;
            return MGMT_ERR_EINVAL;
        }

        if (req->data_sha_len > IMG_MGMT_DATA_SHA_LEN) {
            return MGMT_ERR_EINVAL;
        }

        /*
         * If request includes proper data hash we can check whether there is
         * upload in progress (interrupted due to e.g. link disconnection) with
         * the same data hash so we can just resume it by simply including
         * current upload offset in response.
         */
        if ((req->data_sha_len > 0) && (g_img_mgmt_state.area_id != -1)) {
            if ((g_img_mgmt_state.data_sha_len == req->data_sha_len) &&
                            !memcmp(g_img_mgmt_state.data_sha, req->data_sha,
                                                        req->data_sha_len)) {
                return 0;
            }
        }

        action->area_id = img_mgmt_find_best_area_id();
        if (action->area_id < 0) {
            /* No slot where to upload! */
            *errstr = img_mgmt_err_str_no_slot;
            return MGMT_ERR_ENOMEM;
        }

        if (req->upgrade) {
            /* User specified upgrade-only.  Make sure new image version is
             * greater than that of the currently running image.
             */
            rc = img_mgmt_my_version(&cur_ver);
            if (rc != 0) {
                return MGMT_ERR_EUNKNOWN;
            }

            if (img_mgmt_vercmp(&cur_ver, &hdr->ih_ver) >= 0) {
                *errstr = img_mgmt_err_str_downgrade;
                return MGMT_ERR_EBADSTATE;
            }
        }

#if IMG_MGMT_LAZY_ERASE
        (void) empty;
#else
        rc = zephyr_img_mgmt_flash_check_empty(action->area_id, &empty);
        if (rc) {
            return MGMT_ERR_EUNKNOWN;
        }

        action->erase = !empty;
#endif
    } else {
        /* Continuation of upload. */
        action->area_id = g_img_mgmt_state.area_id;
        action->size = g_img_mgmt_state.size;

        if (req->off != g_img_mgmt_state.off) {
            /*
             * Invalid offset. Drop the data, and respond with the offset we're
             * expecting data for.
             */
            return 0;
        }
    }

    /* Calculate size of flash write. */
    action->write_bytes = req->data_len;
    if (req->off + req->data_len < action->size) {
        /*
         * Respect flash write alignment if not in the last block
         */
        rc = flash_area_open(action->area_id, &fa);
        if (rc) {
            *errstr = img_mgmt_err_str_flash_open_failed;
            return MGMT_ERR_EUNKNOWN;
        }

        rem_bytes = req->data_len % flash_area_align(fa);
        flash_area_close(fa);

        if (rem_bytes) {
            action->write_bytes -= rem_bytes;
        }
    }

    action->proceed = true;
    return 0;
}