import base64
import itertools
import json
import uuid
from datetime import datetime
from functools import partial
from io import BytesIO
from zipfile import BadZipFile

from flask import (
    abort,
    current_app,
    flash,
    redirect,
    render_template,
    request,
    send_file,
    url_for,
)
from notifications_utils.insensitive_dict import InsensitiveDict
from notifications_utils.pdf import pdf_page_count
from notifications_utils.postal_address import PostalAddress
from notifications_utils.recipients import RecipientCSV
from notifications_utils.sanitise_text import SanitiseASCII
from PyPDF2.errors import PdfReadError
from requests import RequestException
from xlrd.biffh import XLRDError
from xlrd.xldate import XLDateError

from app import (
    current_service,
    notification_api_client,
    service_api_client,
    upload_api_client,
)
from app.extensions import antivirus_client
from app.main import main
from app.main.forms import CsvUploadForm, LetterUploadPostageForm, PDFUploadForm
from app.models.contact_list import ContactList
from app.s3_client.s3_letter_upload_client import (
    LetterNotFoundError,
    backup_original_letter_to_s3,
    get_letter_metadata,
    get_letter_pdf_and_metadata,
    get_transient_letter_file_location,
    upload_letter_to_s3,
)
from app.template_previews import TemplatePreview, sanitise_letter
from app.utils import unicode_truncate
from app.utils.csv import Spreadsheet, get_errors_for_csv
from app.utils.letters import (
    get_letter_printing_statement,
    get_letter_validation_error,
)
from app.utils.pagination import (
    generate_next_dict,
    generate_previous_dict,
    get_page_from_request,
)
from app.utils.templates import get_sample_template, get_template
from app.utils.user import user_has_permissions

MAX_FILE_UPLOAD_SIZE = 2 * 1024 * 1024  # 2MB


@main.route("/services/<uuid:service_id>/uploads")
@user_has_permissions()
def uploads(service_id):
    # No tests have been written, this has been quickly prepared for user research.
    # It's also very like that a new view will be created to show uploads.
    uploads = current_service.get_page_of_uploads(page=request.args.get('page'))

    prev_page = None
    if uploads.prev_page:
        prev_page = generate_previous_dict('main.uploads', service_id, uploads.current_page)
    next_page = None
    if uploads.next_page:
        next_page = generate_next_dict('main.uploads', service_id, uploads.current_page)

    if uploads.current_page == 1:
        listed_uploads = (
            current_service.contact_lists +
            current_service.scheduled_jobs +
            uploads
        )
    else:
        listed_uploads = uploads

    return render_template(
        'views/jobs/jobs.html',
        jobs=listed_uploads,
        prev_page=prev_page,
        next_page=next_page,
        now=datetime.utcnow().isoformat(),
    )


@main.route("/services/<uuid:service_id>/uploaded-letters/<simple_date:letter_print_day>")
@user_has_permissions()
def uploaded_letters(service_id, letter_print_day):
    page = get_page_from_request()
    if page is None:
        abort(404, "Invalid page argument ({}).".format(request.args.get('page')))
    uploaded_letters = upload_api_client.get_letters_by_service_and_print_day(
        current_service.id, letter_print_day=letter_print_day, page=page,
    )

    prev_page = None
    if uploaded_letters['links'].get('prev'):
        prev_page = generate_previous_dict('.uploaded_letters', service_id, page, url_args={
            'letter_print_day': letter_print_day
        })
    next_page = None
    if uploaded_letters['links'].get('next'):
        next_page = generate_next_dict('.uploaded_letters', service_id, page, url_args={
            'letter_print_day': letter_print_day
        })
    return render_template(
        'views/uploads/uploaded-letters.html',
        notifications=add_preview_of_content_uploaded_letters(
            uploaded_letters['notifications']
        ),
        prev_page=prev_page,
        next_page=next_page,
        show_pagination=True,
        total=uploaded_letters['total'],
        letter_printing_statement=get_letter_printing_statement(
            'created',
            letter_print_day,
        ),
        letter_print_day=letter_print_day,
        single_notification_url=partial(
            url_for,
            '.view_notification',
            service_id=current_service.id,
            from_uploaded_letters=letter_print_day,
        )
    )


def add_preview_of_content_uploaded_letters(notifications):

    for notification in notifications:
        yield(dict(
            preview_of_content=', '.join(notification.pop('to').splitlines()),
            to=notification['client_reference'],
            **notification
        ))


@main.route("/services/<uuid:service_id>/upload-letter", methods=['GET', 'POST'])
@user_has_permissions('send_messages')
def upload_letter(service_id):
    form = PDFUploadForm()
    error = {}

    if form.validate_on_submit():
        pdf_file_bytes = form.file.data.read()
        original_filename = form.file.data.filename

        if current_app.config['ANTIVIRUS_ENABLED']:
            virus_free = antivirus_client.scan(BytesIO(pdf_file_bytes))
            if not virus_free:
                return invalid_upload_error('Your file contains a virus')

        if len(pdf_file_bytes) > MAX_FILE_UPLOAD_SIZE:
            return invalid_upload_error('Your file is too big', 'Files must be smaller than 2MB.')

        try:
            # TODO: get page count from the sanitise response once template preview handles malformed files nicely
            page_count = pdf_page_count(BytesIO(pdf_file_bytes))
        except PdfReadError:
            current_app.logger.error('Invalid PDF uploaded for service_id: {}'.format(service_id))
            return invalid_upload_error(
                "There’s a problem with your file",
                'Notify cannot read this PDF.<br>Save a new copy of your file and try again.'
            )

        upload_id = uuid.uuid4()
        file_location = get_transient_letter_file_location(service_id, upload_id)

        try:
            response = sanitise_letter(
                BytesIO(pdf_file_bytes),
                upload_id=upload_id,
                allow_international_letters=current_service.has_permission(
                    'international_letters'
                ),
            )
            response.raise_for_status()
        except RequestException as ex:
            if ex.response is not None and ex.response.status_code == 400:
                validation_failed_message = response.json().get('message')
                invalid_pages = response.json().get('invalid_pages')

                status = 'invalid'
                upload_letter_to_s3(
                    pdf_file_bytes,
                    file_location=file_location,
                    status=status,
                    page_count=page_count,
                    filename=original_filename,
                    message=validation_failed_message,
                    invalid_pages=invalid_pages)
            else:
                raise ex
        else:
            response = response.json()
            recipient = response['recipient_address']
            status = 'valid'
            file_contents = base64.b64decode(response['file'].encode())

            upload_letter_to_s3(
                file_contents,
                file_location=file_location,
                status=status,
                page_count=page_count,
                filename=original_filename,
                recipient=recipient)

            backup_original_letter_to_s3(
                pdf_file_bytes,
                upload_id=upload_id,
            )

        return redirect(
            url_for(
                'main.uploaded_letter_preview',
                service_id=current_service.id,
                file_id=upload_id,
            )
        )

    if form.file.errors:
        error = _get_error_from_upload_form(form.file.errors[0])

    return render_template(
        'views/uploads/choose-file.html',
        error=error,
        form=form
    )


def invalid_upload_error(error_title, error_detail=None):
    return render_template(
        'views/uploads/choose-file.html',
        error={'title': error_title, 'detail': error_detail},
        form=PDFUploadForm()
    ), 400


def _get_error_from_upload_form(form_errors):
    error = {}
    if 'PDF' in form_errors:
        error['title'] = 'Wrong file type'
        error['detail'] = form_errors
    else:  # No file was uploaded error
        error['title'] = form_errors

    return error


@main.route("/services/<uuid:service_id>/preview-letter/<uuid:file_id>")
@user_has_permissions('send_messages')
def uploaded_letter_preview(service_id, file_id):
    re_upload_form = PDFUploadForm()

    try:
        metadata = get_letter_metadata(service_id, file_id)
    except LetterNotFoundError as e:
        current_app.logger.warning(e)

        # If the file is missing it's likely because this is a duplicate
        # request, the notification already exists and the file has been
        # moved to a different bucket. Note that the ID of a precompiled
        # notification is always set to the file_id.
        return redirect(url_for(
            '.view_notification',
            service_id=service_id,
            notification_id=file_id,
        ))

    original_filename = metadata.get('filename')
    page_count = metadata.get('page_count')
    status = metadata.get('status')
    error_shortcode = metadata.get('message')
    invalid_pages = metadata.get('invalid_pages')
    postal_address = PostalAddress(metadata.get('recipient', ''))

    if invalid_pages:
        invalid_pages = json.loads(invalid_pages)

    error_message = get_letter_validation_error(error_shortcode, invalid_pages, page_count)
    template_dict = service_api_client.get_precompiled_template(service_id)
    # Override pre compiled letter template postage to none as it has not yet been picked even though
    # the pre compiled letter template has its postage set as second class as the DB currently requires
    # a non null value of postage for letter templates
    template_dict['postage'] = None

    form = LetterUploadPostageForm(
        postage_zone=postal_address.postage
    )

    template = get_template(
        template_dict,
        service_id,
        letter_preview_url=url_for(
            '.view_letter_upload_as_preview',
            service_id=service_id,
            file_id=file_id
        ),
        page_count=page_count
    )

    return render_template(
        'views/uploads/preview.html',
        original_filename=original_filename,
        template=template,
        status=status,
        file_id=file_id,
        message=error_message,
        error_code=error_shortcode,
        form=form,
        allowed_file_extensions=Spreadsheet.ALLOWED_FILE_EXTENSIONS,
        postal_address=postal_address,
        re_upload_form=re_upload_form
    )


@main.route("/services/<uuid:service_id>/preview-letter-image/<uuid:file_id>")
@user_has_permissions('send_messages')
def view_letter_upload_as_preview(service_id, file_id):
    try:
        page = int(request.args.get('page'))
    except ValueError:
        abort(400)

    pdf_file, metadata = get_letter_pdf_and_metadata(service_id, file_id)
    invalid_pages = json.loads(metadata.get('invalid_pages', '[]'))

    if (
        metadata.get('message') == 'content-outside-printable-area' and
        page in invalid_pages
    ):
        return TemplatePreview.from_invalid_pdf_file(pdf_file, page)
    else:
        return TemplatePreview.from_valid_pdf_file(pdf_file, page)


@main.route("/services/<uuid:service_id>/upload-letter/send/<uuid:file_id>", methods=['POST'])
@user_has_permissions('send_messages', restrict_admin_usage=True)
def send_uploaded_letter(service_id, file_id):
    if not current_service.has_permission('letter'):
        abort(403)

    try:
        metadata = get_letter_metadata(service_id, file_id)
    except LetterNotFoundError as e:
        current_app.logger.warning(e)

        # If the file is missing it's likely because this is a duplicate
        # request, the notification already exists and the file has been
        # moved to a different bucket. Note that the ID of a precompiled
        # notification is always set to the file_id.
        return redirect(url_for(
            '.view_notification',
            service_id=service_id,
            notification_id=file_id,
        ))

    if metadata.get('status') != 'valid':
        abort(403)

    postal_address = PostalAddress(metadata.get('recipient'))

    form = LetterUploadPostageForm(
        postage_zone=postal_address.postage
    )

    if not form.validate_on_submit():
        return uploaded_letter_preview(service_id, file_id)

    notification_api_client.send_precompiled_letter(
        service_id,
        metadata.get('filename'),
        file_id,
        form.postage.data,
        postal_address.raw_address,
    )

    return redirect(url_for(
        '.view_notification',
        service_id=service_id,
        notification_id=file_id,
    ))


@main.route("/services/<uuid:service_id>/upload-contact-list", methods=['GET', 'POST'])
@user_has_permissions('send_messages')
def upload_contact_list(service_id):
    form = CsvUploadForm()

    if form.validate_on_submit():
        try:
            upload_id = ContactList.upload(
                current_service.id,
                Spreadsheet.from_file_form(form).as_dict,
            )
            file_name_metadata = unicode_truncate(
                SanitiseASCII.encode(form.file.data.filename),
                1600
            )
            ContactList.set_metadata(
                current_service.id,
                upload_id,
                original_file_name=file_name_metadata
            )
            return redirect(url_for(
                '.check_contact_list',
                service_id=service_id,
                upload_id=upload_id,
            ))
        except (UnicodeDecodeError, BadZipFile, XLRDError):
            flash('Could not read {}. Try using a different file format.'.format(
                form.file.data.filename
            ))
        except (XLDateError):
            flash((
                '{} contains numbers or dates that Notify cannot understand. '
                'Try formatting all columns as ‘text’ or export your file as CSV.'
            ).format(
                form.file.data.filename
            ))
    elif form.errors:
        # just show the first error, as we don't expect the form to have more
        # than one, since it only has one field
        first_field_errors = list(form.errors.values())[0]
        flash(first_field_errors[0])

    return render_template(
        'views/uploads/contact-list/upload.html',
        form=form,
        allowed_file_extensions=Spreadsheet.ALLOWED_FILE_EXTENSIONS,
    )


@main.route(
    "/services/<uuid:service_id>/check-contact-list/<uuid:upload_id>",
    methods=['GET', 'POST'],
)
@user_has_permissions('send_messages')
def check_contact_list(service_id, upload_id):

    form = CsvUploadForm()

    contents = ContactList.download(service_id, upload_id)
    first_row = contents.splitlines()[0].strip().rstrip(',') if contents else ''
    original_file_name = ContactList.get_metadata(service_id, upload_id).get('original_file_name', '')

    template_type = InsensitiveDict({
        'email address': 'email',
        'phone number': 'sms',
    }).get(first_row)

    recipients = RecipientCSV(
        contents,
        template=get_sample_template(template_type or 'sms'),
        guestlist=itertools.chain.from_iterable(
            [user.name, user.mobile_number, user.email_address]
            for user in current_service.active_users
        ) if current_service.trial_mode else None,
        allow_international_sms=current_service.has_permission('international_sms'),
        max_initial_rows_shown=50,
        max_errors_shown=50,
    )

    non_empty_column_headers = list(filter(None, recipients.column_headers))

    if len(non_empty_column_headers) > 1 or not template_type or not recipients:
        return render_template(
            'views/uploads/contact-list/too-many-columns.html',
            recipients=recipients,
            original_file_name=original_file_name,
            template_type=template_type,
            form=form,
            allowed_file_extensions=Spreadsheet.ALLOWED_FILE_EXTENSIONS
        )

    if recipients.too_many_rows or not len(recipients):
        return render_template(
            'views/uploads/contact-list/column-errors.html',
            recipients=recipients,
            original_file_name=original_file_name,
            form=form,
            allowed_file_extensions=Spreadsheet.ALLOWED_FILE_EXTENSIONS
        )

    row_errors = get_errors_for_csv(recipients, template_type)
    if row_errors:
        return render_template(
            'views/uploads/contact-list/row-errors.html',
            recipients=recipients,
            original_file_name=original_file_name,
            row_errors=row_errors,
            form=form,
            allowed_file_extensions=Spreadsheet.ALLOWED_FILE_EXTENSIONS
        )

    if recipients.has_errors:
        return render_template(
            'views/uploads/contact-list/column-errors.html',
            recipients=recipients,
            original_file_name=original_file_name,
            form=form,
            allowed_file_extensions=Spreadsheet.ALLOWED_FILE_EXTENSIONS
        )

    metadata_kwargs = {
        'row_count': len(recipients),
        'valid': True,
        'original_file_name': original_file_name,
        'template_type': template_type
    }

    ContactList.set_metadata(service_id, upload_id, **metadata_kwargs)

    return render_template(
        'views/uploads/contact-list/ok.html',
        recipients=recipients,
        original_file_name=original_file_name,
        upload_id=upload_id,
    )


@main.route("/services/<uuid:service_id>/save-contact-list/<uuid:upload_id>", methods=['POST'])
@user_has_permissions('send_messages')
def save_contact_list(service_id, upload_id):
    ContactList.create(current_service.id, upload_id)
    return redirect(url_for(
        '.uploads',
        service_id=current_service.id,
    ))


@main.route("/services/<uuid:service_id>/contact-list/<uuid:contact_list_id>", methods=['GET'])
@user_has_permissions('send_messages')
def contact_list(service_id, contact_list_id):
    contact_list = ContactList.from_id(contact_list_id, service_id=service_id)
    return render_template(
        'views/uploads/contact-list/contact-list.html',
        contact_list=contact_list,
        jobs=contact_list.get_jobs(
            page=1,
            limit_days=current_service.get_days_of_retention(contact_list.template_type),
        ),
    )


@main.route("/services/<uuid:service_id>/contact-list/<uuid:contact_list_id>/delete", methods=['GET', 'POST'])
@user_has_permissions('manage_templates')
def delete_contact_list(service_id, contact_list_id):
    contact_list = ContactList.from_id(contact_list_id, service_id=service_id)

    if request.method == 'POST':
        contact_list.delete()
        return redirect(url_for(
            '.uploads',
            service_id=service_id,
        ))

    flash([
        f"Are you sure you want to delete ‘{contact_list.original_file_name}’?",
    ], 'delete')

    return render_template(
        'views/uploads/contact-list/contact-list.html',
        contact_list=contact_list,
        confirm_delete_banner=True,
    )


@main.route("/services/<uuid:service_id>/contact-list/<uuid:contact_list_id>.csv", methods=['GET'])
@user_has_permissions('send_messages')
def download_contact_list(service_id, contact_list_id):
    contact_list = ContactList.from_id(contact_list_id, service_id=service_id)
    return send_file(
        path_or_file=BytesIO(contact_list.contents.encode('utf-8')),
        attachment_filename=contact_list.saved_file_name,
        as_attachment=True,
    )