# Extension to format a paragraph

# Does basic, standard text formatting, and also understands Python

# comment blocks.  Thus, for editing Python source code, this

# extension is really only suitable for reformatting these comment

# blocks or triple-quoted strings.

# Known problems with comment reformatting:

# * If there is a selection marked, and the first line of the

#   selection is not complete, the block will probably not be detected

#   as comments, and will have the normal "text formatting" rules

#   applied.

# * If a comment block has leading whitespace that mixes tabs and

#   spaces, they will not be considered part of the same block.

# * Fancy comments, like this bulleted list, arent handled :-)

import re

from configHandler import idleConf

class FormatParagraph:

    menudefs = [

        ('format', [   # /s/edit/format   dscherer@cmu.edu

            ('Format Paragraph', '<<format-paragraph>>'),

         ])

    ]

    def __init__(self, editwin):

        self.editwin = editwin

    def close(self):

        self.editwin = None

    def format_paragraph_event(self, event):

        maxformatwidth = int(idleConf.GetOption('main','FormatParagraph','paragraph'))

        text = self.editwin.text

        first, last = self.editwin.get_selection_indices()

        if first and last:

            data = text.get(first, last)

            comment_header = ''

        else:

            first, last, comment_header, data = \

                    find_paragraph(text, text.index("insert"))

        if comment_header:

            # Reformat the comment lines - convert to text sans header.

            lines = data.split("\n")

            lines = map(lambda st, l=len(comment_header): st[l:], lines)

            data = "\n".join(lines)

            # Reformat to maxformatwidth chars or a 20 char width, whichever is greater.

            format_width = max(maxformatwidth - len(comment_header), 20)

            newdata = reformat_paragraph(data, format_width)

            # re-split and re-insert the comment header.

            newdata = newdata.split("\n")

            # If the block ends in a \n, we dont want the comment

            # prefix inserted after it. (Im not sure it makes sense to

            # reformat a comment block that isnt made of complete

            # lines, but whatever!)  Can't think of a clean soltution,

            # so we hack away

            block_suffix = ""

            if not newdata[-1]:

                block_suffix = "\n"

                newdata = newdata[:-1]

            builder = lambda item, prefix=comment_header: prefix+item

            newdata = '\n'.join(map(builder, newdata)) + block_suffix

        else:

            # Just a normal text format

            newdata = reformat_paragraph(data, maxformatwidth)

        text.tag_remove("sel", "1.0", "end")

        if newdata != data:

            text.mark_set("insert", first)

            text.undo_block_start()

            text.delete(first, last)

            text.insert(first, newdata)

            text.undo_block_stop()

        else:

            text.mark_set("insert", last)

        text.see("insert")

        return "break"

def find_paragraph(text, mark):

    lineno, col = map(int, mark.split("."))

    line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)

    while text.compare("%d.0" % lineno, "<", "end") and is_all_white(line):

        lineno = lineno + 1

        line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)

    first_lineno = lineno

    comment_header = get_comment_header(line)

    comment_header_len = len(comment_header)

    while get_comment_header(line)==comment_header and \

              not is_all_white(line[comment_header_len:]):

        lineno = lineno + 1

        line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)

    last = "%d.0" % lineno

    # Search back to beginning of paragraph

    lineno = first_lineno - 1

    line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)

    while lineno > 0 and \

              get_comment_header(line)==comment_header and \

              not is_all_white(line[comment_header_len:]):

        lineno = lineno - 1

        line = text.get("%d.0" % lineno, "%d.0 lineend" % lineno)

    first = "%d.0" % (lineno+1)

    return first, last, comment_header, text.get(first, last)

def reformat_paragraph(data, limit):

    lines = data.split("\n")

    i = 0

    n = len(lines)

    while i < n and is_all_white(lines[i]):

        i = i+1

    if i >= n:

        return data

    indent1 = get_indent(lines[i])

    if i+1 < n and not is_all_white(lines[i+1]):

        indent2 = get_indent(lines[i+1])

    else:

        indent2 = indent1

    new = lines[:i]

    partial = indent1

    while i < n and not is_all_white(lines[i]):

        # XXX Should take double space after period (etc.) into account

        words = re.split("(\s+)", lines[i])

        for j in range(0, len(words), 2):

            word = words[j]

            if not word:

                continue # Can happen when line ends in whitespace

            if len((partial + word).expandtabs()) > limit and \

               partial != indent1:

                new.append(partial.rstrip())

                partial = indent2

            partial = partial + word + " "

            if j+1 < len(words) and words[j+1] != " ":

                partial = partial + " "

        i = i+1

    new.append(partial.rstrip())

    # XXX Should reformat remaining paragraphs as well

    new.extend(lines[i:])

    return "\n".join(new)

def is_all_white(line):

    return re.match(r"^\s*$", line) is not None

def get_indent(line):

    return re.match(r"^(\s*)", line).group()

def get_comment_header(line):

    m = re.match(r"^(\s*#*)", line)

    if m is None: return ""

    return m.group(1)