# Part of Odoo. See LICENSE file for full copyright and licensing details.

import base64
import logging
from datetime import timedelta

import requests
from requests.exceptions import ConnectionError as RequestConnectionError

from odoo import _, api, fields, models
from odoo.exceptions import UserError

_logger = logging.getLogger(__name__)


class ProductFetchImageWizard(models.TransientModel):
    _name = 'product.fetch.image.wizard'
    _description = "Fetch product images from Google Images based on the product's barcode number."

    _session = requests.Session()

    @api.model
    def default_get(self, fields_list):
        # Check that the cron has not been deleted and raise an error if so
        ir_cron_fetch_image = self.env.ref(
            'product_images.ir_cron_fetch_image', raise_if_not_found=False
        )
        if not ir_cron_fetch_image:
            raise UserError(_(
                "The scheduled action \"Product Images: Get product images from Google\" has "
                "been deleted. Please contact your administrator to have the action restored "
                "or to reinstall the module \"product_images\"."
            ))

        # Check that the cron is not already triggered and raise an error if so
        cron_triggers_count = self.env['ir.cron.trigger'].search_count(
            [('cron_id', '=', ir_cron_fetch_image.id)]
        )
        if cron_triggers_count > 0:
            raise UserError(_(
                "A task to process products in the background is already running. Please try again"
                "later."
            ))

        # Check if API keys are set without retrieving the values to avoid leaking them
        ICP = self.env['ir.config_parameter']
        google_pse_id_is_set = bool(ICP.get_param('google.pse.id'))
        google_custom_search_key_is_set = bool(ICP.get_param('google.custom_search.key'))
        if not (google_pse_id_is_set and google_custom_search_key_is_set):
            raise UserError(_(
                "The API Key and Search Engine ID must be set in the General Settings."
            ))

        # Compute default values
        if self._context.get('active_model') == 'product.template':
            product_ids = self.env['product.template'].browse(
                self._context.get('active_ids')
            ).product_variant_ids
        else:
            product_ids = self.env['product.product'].browse(
                self._context.get('active_ids')
            )
        nb_products_selected = len(product_ids)
        products_to_process = product_ids.filtered(lambda p: not p.image_1920 and p.barcode)
        nb_products_to_process = len(products_to_process)
        nb_products_unable_to_process = nb_products_selected - nb_products_to_process
        defaults = super().default_get(fields_list)
        defaults.update(
            products_to_process=products_to_process,
            nb_products_selected=nb_products_selected,
            nb_products_to_process=nb_products_to_process,
            nb_products_unable_to_process=nb_products_unable_to_process,
        )
        return defaults

    nb_products_selected = fields.Integer(string="Number of selected products", readonly=True)
    products_to_process = fields.Many2many(
        comodel_name='product.product',
        help="The list of selected products that meet the criteria (have a barcode and no image)",
    )
    nb_products_to_process = fields.Integer(string="Number of products to process", readonly=True)
    nb_products_unable_to_process = fields.Integer(
        string="Number of product unprocessable", readonly=True
    )

    def action_fetch_image(self):
        """ Fetch the images of the first ten products and delegate the remaining to the cron.

        The first ten images are immediately fetched to improve the user experience. This way, they
        can immediately browse the processed products and be assured that the task is running well.
        Also, if any error occurs, it can be thrown to the user. Then, a cron job is triggered to be
        run as soon as possible, unless the daily request limit has been reached. In that case, the
        cron job is scheduled to run a day later.

        :return: A notification to inform the user about the outcome of the action
        :rtype: dict
        """
        self.products_to_process.image_fetch_pending = True  # Flag products to process for the cron

        # Process the first 10 products immediately
        matching_images_count = self._process_products(self._get_products_to_process(10))

        if self._get_products_to_process(1):  # Delegate remaining products to the cron
            # Check that the cron has not been deleted and raise an error if so
            ir_cron_fetch_image = self.env.ref(
                'product_images.ir_cron_fetch_image', raise_if_not_found=False
            )
            if not ir_cron_fetch_image:
                raise UserError(_(
                    "The scheduled action \"Product Images: Get product images from Google\" has "
                    "been deleted. Please contact your administrator to have the action restored "
                    "or to reinstall the module \"product_images\"."
                ))

            # Check that the cron is not already triggered and create a new trigger if not
            cron_triggers_count = self.env['ir.cron.trigger'].search_count(
                [('cron_id', '=', ir_cron_fetch_image.id)]
            )
            if cron_triggers_count == 0:
                self.with_context(automatically_triggered=False)._trigger_fetch_images_cron()
            message = _(
                "Products are processed in the background. Images will be updated progressively."
            )
            warning_type = 'success'
        else:
            message = _(
                "%(matching_images_count)s matching images have been found for %(product_count)s "
                "products.",
                matching_images_count=matching_images_count,
                product_count=len(self.products_to_process)
            )
            warning_type = 'success' if matching_images_count > 0 else 'warning'
        return {
            'type': 'ir.actions.client',
            'tag': 'display_notification',
            'params': {
                'title': _("Product images"),
                'type': warning_type,
                'message': message,
                'next': {'type': 'ir.actions.act_window_close'},
            }
        }

    def _cron_fetch_image(self):
        """ Fetch images of a list of products using their barcode.

        This method is called from a cron job. If the daily request limit is reached, the cron job
        is scheduled to run again a day later.

        :return: None
        """
        # Retrieve 100 products at a time to limit the run time and avoid reaching Google's default
        # rate limit.
        self._process_products(self._get_products_to_process(100))
        if self._get_products_to_process(1):
            self.with_context(automatically_triggered=True)._trigger_fetch_images_cron(
                fields.Datetime.now() + timedelta(minutes=1.0)
            )

    def _get_products_to_process(self, limit=10000):
        """ Get the products that need to be processed and meet the criteria.

        The criteria are to have a barcode and no image. If `products_to_process` is not populated,
        the DB is searched to find matching product records.

        :param int limit: The maximum number of records to return, defaulting to 10000 to match
                          Google's API default rate limit
        :return: The products that meet the criteria
        :rtype: recordset of `product.product`
        """
        products_to_process = self.products_to_process or self.env['product.product'].search(
            [('image_fetch_pending', '=', True)], limit=limit
        )
        return products_to_process.filtered(
            # p.image_fetch_pending needed for self.products_to_process's records that might already
            # have been processed but not yet removed from the list when called from
            # action_fetch_image.
            lambda p: not p.image_1920 and p.barcode and p.image_fetch_pending
        )[:limit]  # Apply the limit after the filter with self.products_to_process for more results

    def _process_products(self, products_to_process):
        """ Fetch an image from the Google Custom Search API for each product.

        We fetch the 10 first image URLs and save the first valid image.

        :param recordset products_to_process: The products for which an image must be fetched, as a
                                              `product.product` recordset
        :return: The number of products for which a matching image was found
        :rtype: int
        :raises UserError: If the project is misconfigured on Google's side
        :raises UserError: If the API Key or Search Engine ID is incorrect
        """
        if not products_to_process:
            return 0

        nb_service_unavailable_codes = 0
        nb_timeouts = 0
        for product in products_to_process:
            # Fetch image URLs and handle eventual errors
            try:
                response = self._fetch_image_urls_from_google(product.barcode)
                if response.status_code == requests.codes.forbidden:
                    raise UserError(_(
                        "The Custom Search API is not enabled in your Google project. Please visit "
                        "your Google Cloud Platform project page and enable it, then retry. If you "
                        "enabled this API recently, please wait a few minutes and retry."
                    ))
                elif response.status_code == requests.codes.service_unavailable:
                    nb_service_unavailable_codes += 1
                    if nb_service_unavailable_codes <= 3:  # Temporary loss of service
                        continue  # Let the image of this product be fetched by the next cron run

                    # The service has not responded more  han 3 times, stop trying for now and wait
                    # for the next cron run.
                    self.with_context(automatically_triggered=True)._trigger_fetch_images_cron(
                        fields.Datetime.now() + timedelta(hours=1.0)
                    )
                    _logger.warning(
                        "received too many service_unavailable responses. delegating remaining "
                        "images to next cron run."
                    )
                    break
                elif response.status_code == requests.codes.too_many_requests:
                    self.with_context(automatically_triggered=True)._trigger_fetch_images_cron(
                        fields.Datetime.now() + timedelta(days=1.0)
                    )
                    _logger.warning(
                        "search quota exceeded. delegating remaining images to next cron run."
                    )
                    break
                elif response.status_code == requests.codes.bad_request:
                    raise UserError(_(
                        "Your API Key or your Search Engine ID is incorrect."
                    ))
            except (RequestConnectionError):
                nb_timeouts += 1
                if nb_timeouts <= 3:  # Temporary loss of service
                    continue  # Let the image of this product be fetched by the next cron run

                # The service has not responded more  han 3 times, stop trying for now and wait for
                # the next cron run.
                self.with_context(automatically_triggered=True)._trigger_fetch_images_cron(
                    fields.Datetime.now() + timedelta(hours=1.0)
                )
                _logger.warning(
                    "encountered too many timeouts. delegating remaining images to next cron run."
                )
                break

            # Fetch image and handle possible error
            response_content = response.json()
            if int(response_content['searchInformation']['totalResults']) > 0:
                for item in response_content['items']:  # Only populated if totalResults > 0
                    try:
                        image = self._get_image_from_url(item['link'])
                        if image:
                            product.image_1920 = image
                            break  # Stop at the first valid image
                    except (
                        RequestConnectionError,
                        UserError,  # Raised when the image couldn't be decoded as base64
                    ):
                        pass  # Move on to the next image

            product.image_fetch_pending = False
            self.env.cr.commit()  # Commit every image in case the cron is killed

        return len(products_to_process.filtered('image_1920'))

    def _fetch_image_urls_from_google(self, barcode):
        """ Fetch the first 10 image URLs from the Google Custom Search API.

        :param string barcode: A product's barcode
        :return: A response or None
        :rtype: Response
        """
        if not barcode:
            return

        ICP = self.env['ir.config_parameter']
        return self._session.get(
            url='https://customsearch.googleapis.com/customsearch/v1',
            params={
                'cx': ICP.get_param('google.pse.id').strip(),
                'safe': 'active',
                'searchType': 'image',
                'key': ICP.get_param('google.custom_search.key').strip(),
                'rights': 'cc_publicdomain,cc_attribute,cc_sharealike',
                'imgSize': 'large',
                'imgType': 'photo',
                'fields': 'searchInformation/totalResults,items(link)',
                'q': barcode,
            }
        )

    def _get_image_from_url(self, url):
        """ Retrieve an image from the URL.

        If the url contains 'x-raw-image:///', the request failed or the response header
        'Content-Type' does not contain 'image/', return None

        :param string url: url of an image
        :return: The retrieved image or None
        :rtype: bytes
        """
        image = None
        if 'x-raw-image:///' not in url:  # Ignore images with incorrect link
            response = self._session.get(url, timeout=5)
            if response.status_code == requests.codes.ok \
                and 'image/' in response.headers['Content-Type']:  # Ignore non-image results
                image = base64.b64encode(response.content)
        return image

    def _trigger_fetch_images_cron(self, at=None):
        """ Create a trigger for the con `ir_cron_fetch_image`.

        By default the cron is scheduled to be executed as soon as possible but
        the optional `at` argument may be given to delay the execution later
        with a precision down to 1 minute.

        :param Optional[datetime.datetime] at:
            When to execute the cron, at one moments in time instead of as soon as possible.
        """
        self.env.ref('product_images.ir_cron_fetch_image')._trigger(at)
        # If two `ir_cron_fetch_image` are triggered automatically, and the first one is not
        # committed, the constrains will return a ValidationError and roll back to the last commit,
        # leaving no `ir_cron_fetch_image` in the schedule.
        self.env.cr.commit()
