from django.http import HttpRequest, HttpResponse
from django.db.models.query import QuerySet

from openpyxl import Workbook
from openpyxl.styles import Font, PatternFill, Alignment

from datetime import date, datetime, timedelta
from typing import List
import calendar

from ..models.weekpref import WeekPreference
from ..models.missions import Training
from ..models.hourbuildings import HourBuilding

def export_selected(request: HttpRequest, queryset: QuerySet[WeekPreference]) -> HttpResponse:

    if not queryset.first():
        raise Exception("Empty queryset")
    
    # Init Variables
    year = date.today().year
    week = queryset.first().week if queryset.first() else date.today().isocalendar().week
    
    # Prepare export filename and http content
    filename = f"{year}-week{week}_export.xlsx"
    response = HttpResponse(content_type='application/vnd.openxmlformats-officedocument.spreadsheetml.sheet')
    response['Content-Disposition'] = f'attachment; filename="{filename}"'

    # Create workbook and sheet
    wb = Workbook()
    ws = wb.active
    if not ws:
        raise Exception("Export: cannot select active workbook")
    ws.title = f"{year} Week {week} Preferences"

    # Header titles  
    days = [f"{datetime.strptime(f"{year} {week} {x}", "%G %V %u").strftime("%A")} {datetime.strptime(f"{year} {week} {x}", "%G %V %u").day}" for x in range(1,8)]
    headers = ["Week", "Student", "Course", *days, "Cell.", "Mail", "Notes"]

    # Header fields positions
    student_index: int = headers.index("Student") + 1
    course_index: int = headers.index("Course") + 1
    cell_index: int = headers.index("Cell.") + 1
    mail_index: int = headers.index("Mail") + 1
    
    # Stile header
    header_fill = PatternFill("solid", fgColor="0e005c")
    bold_white = Font(color="FFFFFF", bold=True)
    bold_black = Font(color="000000", bold=True)
    center = Alignment(horizontal="center", vertical="center")

    # Scrittura header
    for col, h in enumerate(headers, start=1):
        cell = ws.cell(row=1, column=col, value=h)
        cell.fill = header_fill
        cell.font = bold_white
        cell.alignment = center

    # Scrittura dati
    row: int = 2
    row_offset: int = 0
    
    # Fill worksheet with EVERY training and hb for every student
    for i, q in enumerate(queryset.order_by("student__surname", "student__name", "student__course"), start=1):
        student_data: List[str]
        student_phone: str = q.student.phone if q.student.phone else ""
        student_email: str = q.student.email
        if q.student.course:
            student_data = [f"{q.student.surname} {q.student.name}", f"{q.student.course.ctype}-{q.student.course.cnumber}"]
        else:
            student_data = [f"{q.student.surname} {q.student.name}", f"No Course Assigned"]

        # Fill Training mission rows
        mission_name: str
        mission_days: List[str]
        mission_notes: str
        mission_data: List[List[str]] = []
        for t in Training.objects.filter(weekpref = q.id):
            if not t.mission:
                raise Exception("No Training Mission Assigned")
            mission_name = f"{t.mission.mtype}-{t.mission.mnum}"
            mission_days = [
                mission_name if t.monday else "",
                mission_name if t.tuesday else "",
                mission_name if t.wednesday else "",
                mission_name if t.thursday else "",
                mission_name if t.friday else "",
                mission_name if t.saturday else "",
                mission_name if t.sunday else ""
            ]
            mission_notes = t.notes if t.notes else "--"
            mission_data.append([str(week), *student_data, *mission_days, student_phone, student_email, mission_notes])

        # Fill HourBuilding rows
        hb_name: str
        hb_days: List[str]
        hb_notes: str
        hb_data: List[List[str]] = []
        for h in HourBuilding.objects.filter(weekpref = q.id):
            hb_name = f"HB-{h.aircraft}"
            hb_days = [
                hb_name if h.monday else "",
                hb_name if h.tuesday else "",
                hb_name if h.wednesday else "",
                hb_name if h.thursday else "",
                hb_name if h.friday else "",
                hb_name if h.saturday else "",
                hb_name if h.sunday else ""
            ]
            hb_notes = h.notes if h.notes else "--"
            hb_data.append([str(week), *student_data, *hb_days, str(q.student.phone), q.student.email, hb_notes])
         
        # Build rows for table
        student_start: int = row + row_offset
        for r in mission_data + hb_data:
            prev_cell_val: str | None = None
            merge_start: bool = False
            merge_col_start: int = 1
            for j, c in enumerate(r, start=1):
                if prev_cell_val is None:
                    prev_cell_val = c
                cell = ws.cell(row = row + row_offset, column = j, value = c)
                cell.alignment = center
                # Format Student Name
                if j == student_index:
                    cell.font = bold_black
                # Format Course Column
                if j == course_index and q.student.course:
                    cell.fill = PatternFill("solid", fgColor=str(q.student.course.color).lstrip('#').lower())
                # Merge cells in the row
                if c == prev_cell_val and not merge_start:
                    merge_start = True
                    merge_col_start = max(j-1, 1)
                elif c != prev_cell_val and merge_start:
                    merge_start = False
                    ws.merge_cells(start_row=row+row_offset, 
                                   end_row=row+row_offset, 
                                   start_column=merge_col_start,
                                    end_column=max(j-1,1))
            
            # Incement row counter
            row_offset += 1
        
        # End f preferences for this student
        student_end: int = row + row_offset -1
        # Merge Name
        ws.merge_cells(start_row=student_start, end_row=student_end, start_column=student_index, end_column=student_index)
        # Merge Course
        ws.merge_cells(start_row=student_start, end_row=student_end, start_column=course_index, end_column=course_index)
        # Merge Cell
        ws.merge_cells(start_row=student_start, end_row=student_end, start_column=cell_index, end_column=cell_index)
        # Merge Mail
        ws.merge_cells(start_row=student_start, end_row=student_end, start_column=mail_index, end_column=mail_index)

        # Save document in HttpResponse
        wb.save(response)

    return response