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 botocore.exceptions import ClientError
from flask import (
    abort,
    current_app,
    flash,
    redirect,
    render_template,
    request,
    send_file,
    url_for,
)
from notifications_utils.columns import Columns
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.utils 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 (
    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 (
    Spreadsheet,
    generate_next_dict,
    generate_previous_dict,
    get_errors_for_csv,
    get_letter_printing_statement,
    get_letter_validation_error,
    get_page_from_request,
    get_sample_template,
    get_template,
    unicode_truncate,
    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.info('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),
                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)

        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 ClientError as e:
        # if the file's not there, it's probably because we've already created the notification and the letter has been
        # moved to the normal letters-pdf bucket. So lets just bounce out to the notification page
        if e.response['Error']['Code'] == 'NoSuchKey':
            return redirect(url_for(
                '.view_notification',
                service_id=service_id,
                notification_id=file_id,
            ))
        else:
            raise

    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,
        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)

    metadata = get_letter_metadata(service_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
            ))

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


@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 = {
        'emailaddress': 'email',
        'phonenumber': 'sms',
    }.get(Columns.make_key(first_row))

    recipients = RecipientCSV(
        contents,
        template=get_sample_template(template_type or 'sms'),
        whitelist=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,
        )

    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,
        )

    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,
        )

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

    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):
    return render_template(
        'views/uploads/contact-list/contact-list.html',
        contact_list=ContactList.from_id(contact_list_id, service_id=service_id),
    )


@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(
        filename_or_fp=BytesIO(contact_list.contents.encode('utf-8')),
        attachment_filename=contact_list.saved_file_name,
        as_attachment=True,
    )