import copy
from collections import defaultdict
from datetime import datetime, timedelta
from io import BytesIO
from typing import Generator, Union, Any, List, Tuple
from pathlib import Path

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 reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from werkzeug.datastructures import FileStorage

from .exceptions import InvalidNameOrTypeHeaderException
from ..students.models import Student, Group
from ..examination_schedule.models import TermOfDefence


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: FileStorage) -> 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'])
                for _, item in df.iterrows())

    return students


def generate_csv(students_and_groups: List[Tuple[Student, Group]]) -> 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,
             group.cdyd_kod, group.prz_kod, group.tzaj_kod, group.project_supervisor_id,
             None) for student, group in students_and_groups]
    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_range_dates(start_date: datetime, end_date: datetime, step_in_minutes: int) -> \
        Generator[Union[datetime, timedelta], Any, None]:
    current_date = copy.copy(start_date)
    while True:
        next_date = current_date + timedelta(minutes=step_in_minutes)

        if next_date > end_date:
            break
        yield current_date
        current_date = copy.copy(next_date)


def generate_examination_schedule_pdf_file(title: str, nested_term_of_defences: List[List[TermOfDefence]],
                                           base_dir: Path) -> 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
    )

    pdfmetrics.registerFont(TTFont('Lato', base_dir / 'fonts' / 'Lato.ttf'))
    style = getSampleStyleSheet()
    bodyText = style['BodyText']
    bodyText.fontName = 'Lato'
    normal = style["Heading1"]
    normal.alignment = TA_CENTER
    flowables = []

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

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

            members = td.members_of_committee
            # print(members)
            if len(members) == 0:
                committee = ''
            else:
                members_iter = (f"{m.first_name[0]} {m.last_name}" for m in members)
                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