import csv
import os
from io import StringIO

import frappe
from frappe import _
from frappe.utils.csvutils import read_csv_content
from frappe.utils.file_manager import save_file
from frappe.utils.xlsxutils import (
	make_xlsx,
	read_xls_file_from_attached_file,
	read_xlsx_file_from_attached_file,
)


def _trim_cell(value):
	if isinstance(value, str):
		trimmed = value.strip()
		return trimmed if trimmed else None
	return value


def _trim_rows(rows):
	trimmed_cells = 0
	out = []
	for row in rows:
		new_row = []
		for cell in row:
			if isinstance(cell, str):
				original = cell
				trimmed = _trim_cell(cell)
				if original != (trimmed or ""):
					trimmed_cells += 1
				new_row.append(trimmed)
			else:
				new_row.append(cell)
		out.append(new_row)
	return out, trimmed_cells


def _read_rows_from_content(content, extension):
	extension = (extension or "").lower()
	if extension == "csv":
		return read_csv_content(content)
	if extension == "xlsx":
		return read_xlsx_file_from_attached_file(fcontent=content)
	if extension == "xls":
		return read_xls_file_from_attached_file(content)
	frappe.throw(_("Import file must be .csv, .xlsx, or .xls"))


def _write_trimmed_content(rows, extension):
	extension = (extension or "").lower()
	if extension == "csv":
		buffer = StringIO()
		writer = csv.writer(buffer)
		for row in rows:
			writer.writerow(["" if cell is None else cell for cell in row])
		return buffer.getvalue().encode("utf-8"), "csv"

	if extension == "xls":
		extension = "xlsx"

	if extension == "xlsx":
		return make_xlsx(rows, "Import").getvalue(), "xlsx"

	frappe.throw(_("Import file must be .csv, .xlsx, or .xls"))


def _trimmed_filename(original_name, output_extension):
	base, _ = os.path.splitext(original_name or "import")
	return f"{base}_trimmed.{output_extension}"


@frappe.whitelist()
def trim_and_upload_import_file(data_import):
	doc = frappe.get_doc("Data Import", data_import)
	doc.check_permission("write")

	if not doc.import_file:
		frappe.throw(_("Attach an import file first."))

	if doc.google_sheets_url:
		frappe.throw(_("Trim and Upload is only available for attached files, not Google Sheets URLs."))

	file_name = frappe.db.get_value("File", {"file_url": doc.import_file}, "name")
	if not file_name:
		frappe.throw(_("Import file not found in File attachments."))

	source_file = frappe.get_doc("File", file_name)
	content = source_file.get_content()
	extension = os.path.splitext(source_file.file_name or doc.import_file)[1][1:].lower()

	rows = _read_rows_from_content(content, extension)
	if not rows:
		frappe.throw(_("Import file is empty."))

	trimmed_rows, trimmed_cells = _trim_rows(rows)
	output_content, output_extension = _write_trimmed_content(trimmed_rows, extension)
	output_name = _trimmed_filename(source_file.file_name or os.path.basename(doc.import_file), output_extension)

	new_file = save_file(
		output_name,
		output_content,
		dt=doc.doctype,
		dn=doc.name,
		is_private=source_file.is_private,
		df="import_file",
	)

	doc.import_file = new_file.file_url
	doc.template_options = ""
	doc.template_warnings = ""
	doc.save()

	return {
		"import_file": new_file.file_url,
		"file_name": new_file.file_name,
		"trimmed_cells": trimmed_cells,
		"summary": _("Trimmed {0} cell(s) and uploaded {1}.").format(trimmed_cells, new_file.file_name),
	}