"""
Student and course analytics.

Serve miscellaneous course and student data
"""
import datetime
import json

from django.conf import settings
from django.contrib.auth.models import User
from django.core.exceptions import ObjectDoesNotExist
from django.core.serializers.json import DjangoJSONEncoder
from django.core.urlresolvers import reverse
from django.db.models import Count, Q
from edx_proctoring.api import get_exam_violation_report
from opaque_keys.edx.keys import UsageKey

import xmodule.graders as xmgraders
from certificates.models import CertificateStatuses, GeneratedCertificate
from courseware.models import StudentModule
from lms.djangoapps.grades.context import grading_context_for_course
from lms.djangoapps.verify_student.models import SoftwareSecurePhotoVerification
from openedx.core.djangoapps.site_configuration import helpers as configuration_helpers
from shoppingcart.models import (
    CouponRedemption,
    CourseRegCodeItem,
    CourseRegistrationCodeInvoiceItem,
    PaidCourseRegistration,
    RegistrationCodeRedemption
)
from student.models import CourseEnrollment, CourseEnrollmentAllowed

STUDENT_FEATURES = ('id', 'username', 'first_name', 'last_name', 'is_staff', 'email')
PROFILE_FEATURES = ('name', 'language', 'location', 'year_of_birth', 'gender',
                    'level_of_education', 'mailing_address', 'goals', 'meta',
                    'city', 'country')
ORDER_ITEM_FEATURES = ('list_price', 'unit_cost', 'status')
ORDER_FEATURES = ('purchase_time',)

SALE_FEATURES = ('total_amount', 'company_name', 'company_contact_name', 'company_contact_email', 'recipient_name',
                 'recipient_email', 'customer_reference_number', 'internal_reference', 'created')

SALE_ORDER_FEATURES = ('id', 'company_name', 'company_contact_name', 'company_contact_email', 'purchase_time',
                       'customer_reference_number', 'recipient_name', 'recipient_email', 'bill_to_street1',
                       'bill_to_street2', 'bill_to_city', 'bill_to_state', 'bill_to_postalcode',
                       'bill_to_country', 'order_type', 'created')

AVAILABLE_FEATURES = STUDENT_FEATURES + PROFILE_FEATURES
COURSE_REGISTRATION_FEATURES = ('code', 'course_id', 'created_by', 'created_at', 'is_valid')
COUPON_FEATURES = ('code', 'course_id', 'percentage_discount', 'description', 'expiration_date', 'is_active')
CERTIFICATE_FEATURES = ('course_id', 'mode', 'status', 'grade', 'created_date', 'is_active', 'error_reason')

UNAVAILABLE = "[unavailable]"


def sale_order_record_features(course_id, features):
    """
    Return list of sale orders features as dictionaries.

    sales_records(course_id, ['company_name, total_codes', total_amount])
    would return [
        {'company_name': 'group_A', 'total_codes': '1', total_amount:'total_amount1 in decimal'.}
        {'company_name': 'group_B', 'total_codes': '2', total_amount:'total_amount2 in decimal'.}
        {'company_name': 'group_C', 'total_codes': '3', total_amount:'total_amount3 in decimal'.}
    ]
    """
    purchased_courses = PaidCourseRegistration.objects.filter(
        Q(course_id=course_id),
        Q(status='purchased') | Q(status='refunded')
    ).order_by('order')

    purchased_course_reg_codes = CourseRegCodeItem.objects.filter(
        Q(course_id=course_id),
        Q(status='purchased') | Q(status='refunded')
    ).order_by('order')

    def sale_order_info(purchased_course, features):
        """
        convert purchase transactions to dictionary
        """

        sale_order_features = [x for x in SALE_ORDER_FEATURES if x in features]
        order_item_features = [x for x in ORDER_ITEM_FEATURES if x in features]

        # Extracting order information
        sale_order_dict = dict((feature, getattr(purchased_course.order, feature))
                               for feature in sale_order_features)

        quantity = int(purchased_course.qty)
        unit_cost = float(purchased_course.unit_cost)
        sale_order_dict.update({"quantity": quantity})
        sale_order_dict.update({"total_amount": quantity * unit_cost})

        sale_order_dict.update({"logged_in_username": purchased_course.order.user.username})
        sale_order_dict.update({"logged_in_email": purchased_course.order.user.email})

        # Extracting OrderItem information of unit_cost, list_price and status
        order_item_dict = dict((feature, getattr(purchased_course, feature, None))
                               for feature in order_item_features)

        order_item_dict['list_price'] = purchased_course.get_list_price()

        sale_order_dict.update(
            {"total_discount": (order_item_dict['list_price'] - order_item_dict['unit_cost']) * quantity}
        )

        order_item_dict.update({"coupon_code": 'N/A'})

        coupon_redemption = CouponRedemption.objects.select_related('coupon').filter(order_id=purchased_course.order_id)
        # if coupon is redeemed against the order, update the information in the order_item_dict
        if coupon_redemption.exists():
            coupon_codes = [redemption.coupon.code for redemption in coupon_redemption]
            order_item_dict.update({'coupon_code': ", ".join(coupon_codes)})

        sale_order_dict.update(dict(order_item_dict.items()))

        return sale_order_dict

    csv_data = [sale_order_info(purchased_course, features) for purchased_course in purchased_courses]
    csv_data.extend(
        [sale_order_info(purchased_course_reg_code, features)
         for purchased_course_reg_code in purchased_course_reg_codes]
    )
    return csv_data


def sale_record_features(course_id, features):
    """
    Return list of sales features as dictionaries.

    sales_records(course_id, ['company_name, total_codes', total_amount])
    would return [
        {'company_name': 'group_A', 'total_codes': '1', total_amount:'total_amount1 in decimal'.}
        {'company_name': 'group_B', 'total_codes': '2', total_amount:'total_amount2 in decimal'.}
        {'company_name': 'group_C', 'total_codes': '3', total_amount:'total_amount3 in decimal'.}
    ]
    """
    sales = CourseRegistrationCodeInvoiceItem.objects.select_related('invoice').filter(course_id=course_id)

    def sale_records_info(sale, features):
        """
        Convert sales records to dictionary

        """
        invoice = sale.invoice
        sale_features = [x for x in SALE_FEATURES if x in features]
        course_reg_features = [x for x in COURSE_REGISTRATION_FEATURES if x in features]

        # Extracting sale information
        sale_dict = dict((feature, getattr(invoice, feature))
                         for feature in sale_features)

        total_used_codes = RegistrationCodeRedemption.objects.filter(
            registration_code__in=sale.courseregistrationcode_set.all()
        ).count()
        sale_dict.update({"invoice_number": invoice.id})
        sale_dict.update({"total_codes": sale.courseregistrationcode_set.all().count()})
        sale_dict.update({'total_used_codes': total_used_codes})

        codes = [reg_code.code for reg_code in sale.courseregistrationcode_set.all()]

        # Extracting registration code information
        if len(codes) > 0:
            obj_course_reg_code = sale.courseregistrationcode_set.all()[:1].get()
            course_reg_dict = dict((feature, getattr(obj_course_reg_code, feature))
                                   for feature in course_reg_features)
        else:
            course_reg_dict = dict((feature, None)
                                   for feature in course_reg_features)

        course_reg_dict['course_id'] = course_id.to_deprecated_string()
        course_reg_dict.update({'codes': ", ".join(codes)})
        sale_dict.update(dict(course_reg_dict.items()))

        return sale_dict

    return [sale_records_info(sale, features) for sale in sales]


def issued_certificates(course_key, features):
    """
    Return list of issued certificates as dictionaries against the given course key.

    issued_certificates(course_key, features)
    would return [
        {course_id: 'abc', 'total_issued_certificate': '5', 'mode': 'honor'}
        {course_id: 'abc', 'total_issued_certificate': '10', 'mode': 'verified'}
        {course_id: 'abc', 'total_issued_certificate': '15', 'mode': 'Professional Education'}
    ]
    """

    report_run_date = datetime.date.today().strftime("%B %d, %Y")
    certificate_features = [x for x in CERTIFICATE_FEATURES if x in features]
    generated_certificates = list(GeneratedCertificate.eligible_certificates.filter(
        course_id=course_key,
        status=CertificateStatuses.downloadable
    ).values(*certificate_features).annotate(total_issued_certificate=Count('mode')))

    # Report run date
    for data in generated_certificates:
        data['report_run_date'] = report_run_date
        data['course_id'] = str(data['course_id'])

    return generated_certificates


def enrolled_students_features(course_key, features):
    """
    Return list of student features as dictionaries.

    enrolled_students_features(course_key, ['username', 'first_name'])
    would return [
        {'username': 'username1', 'first_name': 'firstname1'}
        {'username': 'username2', 'first_name': 'firstname2'}
        {'username': 'username3', 'first_name': 'firstname3'}
    ]
    """
    include_cohort_column = 'cohort' in features
    include_team_column = 'team' in features
    include_enrollment_mode = 'enrollment_mode' in features
    include_verification_status = 'verification_status' in features

    students = User.objects.filter(
        courseenrollment__course_id=course_key,
        courseenrollment__is_active=1,
    ).order_by('username').select_related('profile')

    if include_cohort_column:
        students = students.prefetch_related('course_groups')

    if include_team_column:
        students = students.prefetch_related('teams')

    def extract_attr(student, feature):
        """Evaluate a student attribute that is ready for JSON serialization"""
        attr = getattr(student, feature)
        try:
            DjangoJSONEncoder().default(attr)
            return attr
        except TypeError:
            return unicode(attr)

    def extract_student(student, features):
        """ convert student to dictionary """
        student_features = [x for x in STUDENT_FEATURES if x in features]
        profile_features = [x for x in PROFILE_FEATURES if x in features]

        # For data extractions on the 'meta' field
        # the feature name should be in the format of 'meta.foo' where
        # 'foo' is the keyname in the meta dictionary
        meta_features = []
        for feature in features:
            if 'meta.' in feature:
                meta_key = feature.split('.')[1]
                meta_features.append((feature, meta_key))

        student_dict = dict((feature, extract_attr(student, feature))
                            for feature in student_features)
        profile = student.profile
        if profile is not None:
            profile_dict = dict((feature, extract_attr(profile, feature))
                                for feature in profile_features)
            student_dict.update(profile_dict)

            # now fetch the requested meta fields
            meta_dict = json.loads(profile.meta) if profile.meta else {}
            for meta_feature, meta_key in meta_features:
                student_dict[meta_feature] = meta_dict.get(meta_key)

        if include_cohort_column:
            # Note that we use student.course_groups.all() here instead of
            # student.course_groups.filter(). The latter creates a fresh query,
            # therefore negating the performance gain from prefetch_related().
            student_dict['cohort'] = next(
                (cohort.name for cohort in student.course_groups.all() if cohort.course_id == course_key),
                "[unassigned]"
            )

        if include_team_column:
            student_dict['team'] = next(
                (team.name for team in student.teams.all() if team.course_id == course_key),
                UNAVAILABLE
            )

        if include_enrollment_mode or include_verification_status:
            enrollment_mode = CourseEnrollment.enrollment_mode_for_user(student, course_key)[0]
            if include_verification_status:
                student_dict['verification_status'] = SoftwareSecurePhotoVerification.verification_status_for_user(
                    student,
                    course_key,
                    enrollment_mode
                )
            if include_enrollment_mode:
                student_dict['enrollment_mode'] = enrollment_mode

        return student_dict

    return [extract_student(student, features) for student in students]


def list_may_enroll(course_key, features):
    """
    Return info about students who may enroll in a course as a dict.

    list_may_enroll(course_key, ['email'])
    would return [
        {'email': 'email1'}
        {'email': 'email2'}
        {'email': 'email3'}
    ]

    Note that result does not include students who may enroll and have
    already done so.
    """
    may_enroll_and_unenrolled = CourseEnrollmentAllowed.may_enroll_and_unenrolled(course_key)

    def extract_student(student, features):
        """
        Build dict containing information about a single student.
        """
        return dict((feature, getattr(student, feature)) for feature in features)

    return [extract_student(student, features) for student in may_enroll_and_unenrolled]


def get_proctored_exam_results(course_key, features):
    """
    Return info about proctored exam results in a course as a dict.
    """
    comment_statuses = ['Rules Violation', 'Suspicious']

    def extract_details(exam_attempt, features):
        """
        Build dict containing information about a single student exam_attempt.
        """
        proctored_exam = dict(
            (feature, exam_attempt.get(feature)) for feature in features if feature in exam_attempt
        )

        for status in comment_statuses:
            comment_list = exam_attempt.get(
                '{status} Comments'.format(status=status),
                []
            )
            proctored_exam.update({
                '{status} Count'.format(status=status): len(comment_list),
                '{status} Comments'.format(status=status): '; '.join(comment_list),
            })

        return proctored_exam

    exam_attempts = get_exam_violation_report(course_key)
    return [extract_details(exam_attempt, features) for exam_attempt in exam_attempts]


def coupon_codes_features(features, coupons_list, course_id):
    """
    Return list of Coupon Codes as dictionaries.

    coupon_codes_features
    would return [
        {'course_id': 'edX/Open_DemoX/edx_demo_course,, 'discount': '213'  ..... }
        {'course_id': 'edX/Open_DemoX/edx_demo_course,, 'discount': '234'  ..... }
    ]
    """

    def extract_coupon(coupon, features):
        """ convert coupon_codes to dictionary
        :param coupon_codes:
        :param features:
        """
        coupon_features = [x for x in COUPON_FEATURES if x in features]

        coupon_dict = dict((feature, getattr(coupon, feature)) for feature in coupon_features)
        coupon_redemptions = coupon.couponredemption_set.filter(
            order__status="purchased"
        )

        coupon_dict['code_redeemed_count'] = coupon_redemptions.count()

        seats_purchased_using_coupon = 0
        total_discounted_amount = 0
        for coupon_redemption in coupon_redemptions:
            cart_items = coupon_redemption.order.orderitem_set.all().select_subclasses()
            found_items = []
            for item in cart_items:
                if getattr(item, 'course_id', None):
                    if item.course_id == course_id:
                        found_items.append(item)
            for order_item in found_items:
                seats_purchased_using_coupon += order_item.qty
                discounted_amount_for_item = float(
                    order_item.list_price * order_item.qty) * (float(coupon.percentage_discount) / 100)
                total_discounted_amount += discounted_amount_for_item

        coupon_dict['total_discounted_seats'] = seats_purchased_using_coupon
        coupon_dict['total_discounted_amount'] = total_discounted_amount

        # We have to capture the redeemed_by value in the case of the downloading and spent registration
        # codes csv. In the case of active and generated registration codes the redeemed_by value will be None.
        # They have not been redeemed yet

        coupon_dict['expiration_date'] = coupon.display_expiry_date
        coupon_dict['course_id'] = coupon_dict['course_id'].to_deprecated_string()
        return coupon_dict
    return [extract_coupon(coupon, features) for coupon in coupons_list]


def list_problem_responses(course_key, problem_location):
    """
    Return responses to a given problem as a dict.

    list_problem_responses(course_key, problem_location)

    would return [
        {'username': u'user1', 'state': u'...'},
        {'username': u'user2', 'state': u'...'},
        {'username': u'user3', 'state': u'...'},
    ]

    where `state` represents a student's response to the problem
    identified by `problem_location`.
    """
    problem_key = UsageKey.from_string(problem_location)
    # Are we dealing with an "old-style" problem location?
    run = problem_key.run
    if not run:
        problem_key = UsageKey.from_string(problem_location).map_into_course(course_key)
    if problem_key.course_key != course_key:
        return []

    smdat = StudentModule.objects.filter(
        course_id=course_key,
        module_state_key=problem_key
    )
    smdat = smdat.order_by('student')

    return [
        {'username': response.student.username, 'state': response.state}
        for response in smdat
    ]


def course_registration_features(features, registration_codes, csv_type):
    """
    Return list of Course Registration Codes as dictionaries.

    course_registration_features
    would return [
        {'code': 'code1', 'course_id': 'edX/Open_DemoX/edx_demo_course, ..... }
        {'code': 'code2', 'course_id': 'edX/Open_DemoX/edx_demo_course, ..... }
    ]
    """

    def extract_course_registration(registration_code, features, csv_type):
        """ convert registration_code to dictionary
        :param registration_code:
        :param features:
        :param csv_type:
        """
        site_name = configuration_helpers.get_value('SITE_NAME', settings.SITE_NAME)
        registration_features = [x for x in COURSE_REGISTRATION_FEATURES if x in features]

        course_registration_dict = dict((feature, getattr(registration_code, feature)) for feature in registration_features)
        course_registration_dict['company_name'] = None
        if registration_code.invoice_item:
            course_registration_dict['company_name'] = registration_code.invoice_item.invoice.company_name
        course_registration_dict['redeemed_by'] = None
        if registration_code.invoice_item:
            sale_invoice = registration_code.invoice_item.invoice
            course_registration_dict['invoice_id'] = sale_invoice.id
            course_registration_dict['purchaser'] = sale_invoice.recipient_name
            course_registration_dict['customer_reference_number'] = sale_invoice.customer_reference_number
            course_registration_dict['internal_reference'] = sale_invoice.internal_reference

        course_registration_dict['redeem_code_url'] = 'http://{base_url}{redeem_code_url}'.format(
            base_url=site_name,
            redeem_code_url=reverse('register_code_redemption',
                                    kwargs={'registration_code': registration_code.code})
        )
        # we have to capture the redeemed_by value in the case of the downloading and spent registration
        # codes csv. In the case of active and generated registration codes the redeemed_by value will be None.
        #  They have not been redeemed yet
        if csv_type is not None:
            try:
                redemption_set = registration_code.registrationcoderedemption_set
                redeemed_by = redemption_set.get(registration_code=registration_code).redeemed_by
                course_registration_dict['redeemed_by'] = redeemed_by.email
            except ObjectDoesNotExist:
                pass

        course_registration_dict['course_id'] = course_registration_dict['course_id'].to_deprecated_string()
        return course_registration_dict
    return [extract_course_registration(code, features, csv_type) for code in registration_codes]


def dump_grading_context(course):
    """
    Render information about course grading context
    (e.g. which problems are graded in what assignments)
    Useful for debugging grading_policy.json and policy.json

    Returns HTML string
    """
    hbar = "{}\n".format("-" * 77)
    msg = hbar
    msg += "Course grader:\n"

    msg += '%s\n' % course.grader.__class__
    graders = {}
    if isinstance(course.grader, xmgraders.WeightedSubsectionsGrader):
        msg += '\n'
        msg += "Graded sections:\n"
        for subgrader, category, weight in course.grader.subgraders:
            msg += "  subgrader=%s, type=%s, category=%s, weight=%s\n"\
                % (subgrader.__class__, subgrader.type, category, weight)
            subgrader.index = 1
            graders[subgrader.type] = subgrader
    msg += hbar
    msg += "Listing grading context for course %s\n" % course.id.to_deprecated_string()

    gcontext = grading_context_for_course(course)
    msg += "graded sections:\n"

    msg += '%s\n' % gcontext['all_graded_subsections_by_type'].keys()
    for (gsomething, gsvals) in gcontext['all_graded_subsections_by_type'].items():
        msg += "--> Section %s:\n" % (gsomething)
        for sec in gsvals:
            sdesc = sec['subsection_block']
            frmat = getattr(sdesc, 'format', None)
            aname = ''
            if frmat in graders:
                gform = graders[frmat]
                aname = '%s %02d' % (gform.short_label, gform.index)
                gform.index += 1
            elif sdesc.display_name in graders:
                gform = graders[sdesc.display_name]
                aname = '%s' % gform.short_label
            notes = ''
            if getattr(sdesc, 'score_by_attempt', False):
                notes = ', score by attempt!'
            msg += "      %s (format=%s, Assignment=%s%s)\n"\
                % (sdesc.display_name, frmat, aname, notes)
    msg += "all graded blocks:\n"
    msg += "length=%d\n" % gcontext['count_all_graded_blocks']
    msg = '<pre>%s</pre>' % msg.replace('<', '&lt;')
    return msg
