import logging
from io import BytesIO

import pandas as pd
from fastapi import UploadFile
from fasthtml.components import *

from myfasthtml.controls.BaseCommands import BaseCommands
from myfasthtml.controls.helpers import mk
from myfasthtml.core.commands import Command
from myfasthtml.core.dbmanager import DbObject
from myfasthtml.core.instances import MultipleInstance

logger = logging.getLogger("FileUpload")


class FileUploadState(DbObject):
  def __init__(self, owner):
    super().__init__(owner)
    with self.initializing():
      # persisted in DB
      
      # must not be persisted in DB (prefix ns_ = no_saving_)
      self.ns_file_name: str | None = None
      self.ns_sheets_names: list | None = None
      self.ns_selected_sheet_name: str | None = None
      self.ns_file_content: bytes | None = None


class Commands(BaseCommands):
  def __init__(self, owner):
    super().__init__(owner)
  
  def upload_file(self):
    return Command("UploadFile", "Upload file", self._owner.upload_file).htmx(target=f"#sn_{self._id}")


class FileUpload(MultipleInstance):
  """
  Represents a file upload component.

  This class provides functionality to handle the uploading process of a file,
  extract sheet names from an Excel file, and enables users to select a specific
  sheet for further processing. It integrates commands and state management
  to ensure smooth operation within a parent application.
  """
  
  def __init__(self, parent, _id=None, **kwargs):
    super().__init__(parent, _id=_id, **kwargs)
    self.commands = Commands(self)
    self._state = FileUploadState(self)
  
  def upload_file(self, file: UploadFile):
    logger.debug(f"upload_file: {file=}")
    if file:
      self._state.ns_file_content = file.file.read()
      self._state.ns_sheets_names = self.get_sheets_names(self._state.ns_file_content)
      self._state.ns_selected_sheet_name = self._state.ns_sheets_names[0] if len(self._state.ns_sheets_names) > 0 else 0
    
    return self.mk_sheet_selector()
  
  def mk_sheet_selector(self):
    options = [Option("Choose a file...", selected=True, disabled=True)] if self._state.ns_sheets_names is None else \
      [Option(
        name,
        selected=True if name == self._state.ns_selected_sheet_name else None,
      ) for name in self._state.ns_sheets_names]
    
    return Select(
      *options,
      name="sheet_name",
      id=f"sn_{self._id}",  # sn stands for 'sheet name'
      cls="select select-bordered select-sm w-full ml-2"
    )
  
  def get_content(self):
    return self._state.ns_file_content
    
  
  @staticmethod
  def get_sheets_names(file_content):
    try:
      excel_file = pd.ExcelFile(BytesIO(file_content))
      sheet_names = excel_file.sheet_names
    except Exception as ex:
      logger.error(f"get_sheets_names: {ex=}")
      sheet_names = []
    
    return sheet_names
  
  def render(self):
    return Div(
      Div(
        mk.mk(Input(type='file',
                    name='file',
                    id=f"fi_{self._id}",  # fn stands for 'file name'
                    value=self._state.ns_file_name,
                    hx_preserve="true",
                    hx_encoding='multipart/form-data',
                    cls="file-input file-input-bordered file-input-sm w-full",
                    ),
              command=self.commands.upload_file()
              ),
        self.mk_sheet_selector(),
        cls="flex"
      ),
      mk.dialog_buttons(),
    )
  
  def __ft__(self):
    return self.render()