# -*- coding: utf-8 -*-

# "fold" is a well-known Linux tool that wraps a text file at N columns, and
# optionally splits lines at spaces with the -s option. Sadly it does not work
# well with accents and other special characters bigger than one byte, as it
# will incorrectly think that the line is longer than it really is.

# "pfold" (proper fold) strives to work correctly in the aforementioned cases by
# adding Unicode support (UTF-8). It has -w/--width and -s/--spaces switches.
# It will write the result to standard output just like "fold" does.

# Usage:
#     pfold.py FILE [-s/--spaces] [-w/--width=WIDTH]


import argparse
from argparse import RawTextHelpFormatter # Show newlines in usage text.


USAGE_TEXT = (
	"Wraps FILE at WIDTH columns (default 80), optionally breaking sentences at spaces.\n"
	"The result will be written to standard output. Use redirects (>, >>) to save it.\n"
	"Unlike Linux \"fold\", it correctly supports UTF-8 (like accented characters)."
)


def main():
	argParser = argparse.ArgumentParser(description=USAGE_TEXT, formatter_class=RawTextHelpFormatter)
	argParser.add_argument("file", help="The input file to process.")
	argParser.add_argument("-s", "--spaces", required=False, action='store_true', help="Break lines at spaces.")
	argParser.add_argument("-w", "--width", dest="width", type=int, required=False, help="use WIDTH columns instead of 80.", default=80)
	args = argParser.parse_args()

	try:
		# Open the file.
		with open(args.file, "r", encoding="utf-8") as inputFile:
			# Initialize variables.
			finalResult = []
			currentLine = ""
			characterCount = 0
			lastSpacePos = -1

			# Read it line by line.
			for line in inputFile:
				# Read the line character by character.
				for char in line:
					# Do we have N characters already?
					if characterCount == args.width:
						# If character number 81 is a space, or a newline...
						if char == ' ' or char == '\n':
							finalResult.append(currentLine)
							# Reset the line data.
							currentLine = ""
							characterCount = 0
							lastSpacePos = -1
						else:
							# Do we have to wrap the line at the last space?
							if args.spaces:
								# First, we see if there was no space in this line.
								if lastSpacePos == -1:
									# In that case, this is a line filled with N symbols (letters, numbers...) and no spaces.
									finalResult.append(currentLine)
									# We begin a new line with the 81st character.
									currentLine = char
									characterCount = 1
									lastSpacePos = -1
								else:
									# We take the first part of the line, from the beginning to the last space.
									firstPart = currentLine[:lastSpacePos]
									# And the last part, from there to the end.
									lastPart = currentLine[lastSpacePos:]
									# We add the first part to the file, plus a newline.
									finalResult.append(firstPart)
									# And begin another line with the last part and the 81st character.
									currentLine = lastPart + char
									characterCount = len(currentLine)
									lastSpacePos = -1
							# Do we just wrap here?
							else:
								finalResult.append(currentLine)
								# We begin a new line with the 81st character.
								currentLine = char
								characterCount = 1
								lastSpacePos = -1
					# Still less than N characters?
					else:
						# Add to temporal line and increment count.
						currentLine += char
						characterCount += 1
						# Also, if this character is a space, we mark its position.
						if char == ' ':
							lastSpacePos = characterCount

				# Reached end of line, reset count and add to final file.
				finalResult.append(currentLine)
				currentLine = ""
				characterCount = 0
				lastSpacePos = -1

			# We print to standard output, skipping the final newline.
			print("\n".join(finalResult), end="")

	except FileNotFoundError:
		print(f"Error: The file '{args.file}' was not found.")
	except Exception as e:
		print(f"An error occurred: {e}")


if __name__ == "__main__":
	main()