import datetime
from collections import defaultdict
from io import BytesIO
from itertools import chain
from typing import Generator, Any, List

import pandas as pd
from reportlab.lib import colors
from reportlab.lib.enums import TA_CENTER
from reportlab.lib.styles import getSampleStyleSheet
from reportlab.lib.units import mm, inch
from reportlab.platypus import SimpleDocTemplate, Paragraph, PageBreak, Table

from .exceptions import InvalidNameOrTypeHeaderException
from ..students.models import Student
from ..examination_schedule.models import Enrollment


def check_columns(df: pd.DataFrame) -> bool:
    headers = set(df.keys().values)
    columns = ['NAZWISKO', 'IMIE', 'INDEKS', 'PESEL', 'EMAIL']

    if len(headers - set(columns)) != 0:
        return False

    flag = True
    col_types = ['object', 'object', 'int', 'float64', 'object']

    for name, col_type in zip(columns, col_types):
        if not str(df.dtypes[name]).startswith(col_type):
            flag = False
            break

    return flag


def parse_csv(file, mode) -> Generator[Student, Any, None]:
    df = pd.read_csv(file)

    if not check_columns(df):
        raise InvalidNameOrTypeHeaderException

    students = (Student(last_name=dict(item.items())['NAZWISKO'],
                        first_name=dict(item.items())['IMIE'],
                        index=dict(item.items())['INDEKS'],
                        pesel=str(int(dict(item.items())['PESEL'])) if not pd.isna(
                            dict(item.items())['PESEL']) else None,
                        email=dict(item.items())['EMAIL'],
                        mode=mode)
                for _, item in df.iterrows())

    return students


def generate_csv(students: List[Student]) -> str:
    headers = ['PESEL', 'INDEKS', 'IMIE', 'NAZWISKO', 'EMAIL', 'CDYD_KOD', 'PRZ_KOD', 'TZAJ_KOD', 'GR_NR', 'PRG_KOD']
    data = [(student.pesel, student.index, student.first_name, student.last_name, student.email,
             student.group.cdyd_kod, student.group.prz_kod, student.group.tzaj_kod, student.group.project_supervisor_id,
             None) for student in students]
    dataframe = defaultdict(list)
    for row in data:
        for idx, item in enumerate(row):
            dataframe[headers[idx]].append(item)

    df = pd.DataFrame(dataframe)
    return df.to_csv(index=False)


def generate_examination_schedule_pdf_file(title: str, nested_enrollments: List[List[Enrollment]]) -> bytes:
    pagesize = (297 * mm, 210 * mm)
    headers = ["lp.", "Godzina", "Nazwa projektu", "Opiekun", "Zespol", "Komisja"]
    pdf_buffer = BytesIO()
    my_doc = SimpleDocTemplate(
        pdf_buffer,
        pagesize=pagesize,
        topMargin=1 * inch,
        leftMargin=1 * inch,
        rightMargin=1 * inch,
        bottomMargin=1 * inch,
        title=title
    )

    style = getSampleStyleSheet()
    bodyText = style['BodyText']
    bodyText.fontName = 'Helvetica'
    normal = style["Heading1"]
    normal.alignment = TA_CENTER
    flowables = []

    # print(nested_enrollments)
    for enrollments in nested_enrollments:
        if len(enrollments) == 0:
            continue
        date = datetime.datetime.strftime(enrollments[0].start_date, '%d/%m/%Y')
        paragraph_1 = Paragraph(f"{title} ~ {date}", normal)
        flowables.append(paragraph_1)
        data = [headers]

        for idx, e in enumerate(enrollments, start=1):
            new_date = e.start_date + datetime.timedelta(hours=2)
            group_name = e.group.name if e.group is not None else ""
            if group_name != '':
                ps = e.group.project_supervisor
                project_supervisor_fullname = f"{ps.first_name[0]}. {ps.last_name}"
                students = e.group.students
                # print(students)
                team = ", ".join([f"{s.first_name} {s.last_name}" for s in students])
            else:
                project_supervisor_fullname = ""
                team = ""

            members = e.committee.members
            # print(members)
            if len(members) == 0:
                committee = ''
            else:
                members_iter = (f"{m.first_name[0]} {m.last_name}" for m in members)
                if project_supervisor_fullname != '':
                    members_iter = chain(members_iter, [project_supervisor_fullname])

                committee = ", ".join(members_iter)

            data.append([str(idx), new_date.strftime("%H:%M"),
                         Paragraph(group_name, bodyText),
                         Paragraph(project_supervisor_fullname, bodyText),
                         Paragraph(team, bodyText),
                         Paragraph(committee, bodyText),
                         ])
        # print(data)

        table = Table(data=data,
                      style=[
                          ('GRID', (0, 0), (-1, -1), 0.5, colors.black),
                          ('BACKGROUND', (0, 0), (-1, 0), colors.HexColor("#A6F1A6")),
                          ('BACKGROUND', (0, 0), (1, -1), colors.HexColor("#A6F1A6"))
                      ],
                      colWidths=[0.25 * inch, 0.7 * inch, 1.6 * inch, 1.5 * inch, 4 * inch, 3 * inch]
                      )
        flowables.append(table)
        flowables.append(PageBreak())

    my_doc.build(flowables)
    pdf_value = pdf_buffer.getvalue()
    pdf_buffer.close()
    return pdf_value