init

README.md

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+# Mail Format
+
+By default, this script accepts its input on `stdin` and prints to `stdout`.
+This makes it well suited for use with an editor like Helix. It has no
+dependencies besides the standard Python interpreter, and was written and tested
+against Python 3.13.2.
+
+**Features:**
+
+- Wraps emails at specified columns.
+- Automatically reflows paragraphs.
+- Squashes consecutive paragraph breaks.
+- Preserves:
+  - Any long word not broken by spaces (e.g. URLs, email addresses).
+  - Quoted lines.
+  - Indented lines.
+  - Lists.
+  - Markdown-style code blocks.
+  - Usenet-style signature block at EOF.
+  - Sign-offs.
+
+**Usage:**
+
+```
+usage: format.py [-h] [-w WIDTH] [-b] [--no-replace-whitespace] [--no-reflow]
+                 [--no-signoff] [--no-signature] [--no-squash] [-i INPUT] [-o OUTPUT]
+
+Formatter for plain text email.
+"--no-*" options are NOT passed by default.
+
+options:
+  -h, --help            show this help message and exit
+  -w, --width WIDTH     Text width for wrapping. (default: 74)
+  -b, --break-long-words
+                        Break long words while wrapping. (default: False)
+  --no-replace-whitespace
+                        Don't normalize whitespace when wrapping.
+  --no-reflow           Don't reflow lines.
+  --no-signoff          Don't preserve signoff line breaks.
+  --no-signature        Don't preserve signature block.
+  --no-squash           Don't squash consecutive paragraph breaks.
+  -i, --input INPUT     Input file. (default: STDIN)
+  -o, --output OUTPUT   Output file. (default: STDOUT)
+```

mailfmt.py

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+#!/bin/env python
+
+# Simple text-wrapping script for email.
+# Preserves code blocks, quotes, and signature.
+# Automatically joins and re-wraps paragraphs to
+# ensure even spacing & avoid ugly wrapping.
+# Preserves signoffs, eg: Yours truly,\nJohn Doe
+# Signoff heuristic:
+# 1-5 words ending with a comma, followed by
+# 1-5 words that each start with capital letters.
+# Author: Daniel Fichtinger
+# License: MIT
+
+import textwrap
+import sys
+import re
+import argparse
+
+paragraph: list[str] = []
+skipping = False
+squash = True
+prev_is_parbreak = False
+out_stream = sys.stdout
+reflow = True
+width = 74
+break_long_words = False
+replace_whitespace = True
+
+
+def pprint(string: str):
+    if not squash:
+        print(string, file=out_stream)
+    else:
+        parbreak = not string
+        global prev_is_parbreak
+        if skipping or not (parbreak and prev_is_parbreak):
+            print(string, file=out_stream)
+        prev_is_parbreak = parbreak
+
+
+def wrap(text: str):
+    return textwrap.wrap(
+        text,
+        width=width,
+        break_long_words=break_long_words,
+        replace_whitespace=replace_whitespace,
+    )
+
+
+def flush_paragraph():
+    if paragraph:
+        if reflow:
+            joined = " ".join(paragraph)
+            wrapped = wrap(joined)
+            pprint("\n".join(wrapped))
+        else:
+            for line in paragraph:
+                for wrapped_line in wrap(line):
+                    pprint(wrapped_line)
+        paragraph.clear()
+
+
+signoff_cache: str = ""
+
+
+def check_signoff(line: str) -> bool:
+    if not line:
+        return False
+    words = line.split()
+    n = len(words)
+    # first potential signoff line
+    if not signoff_cache and 1 <= n <= 5 and line[-1] == ",":
+        return True
+    # second potential line
+    elif signoff_cache and 1 <= n <= 5 and line[-1].isalpha():
+        for w in words:
+            if not w[0].isupper():
+                return False
+        return True
+    else:
+        return False
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description='Formatter for plain text email.\n"--no-*" options are NOT passed by default.',
+        epilog="""
+Author : Daniel Fichtinger
+License: MIT
+Contact: daniel@ficd.ca
+        """,
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    parser.add_argument(
+        "-w",
+        "--width",
+        required=False,
+        help="Text width for wrapping. (default: %(default)s)",
+        default=width,
+        type=int,
+    )
+    parser.add_argument(
+        "-b",
+        "--break-long-words",
+        required=False,
+        help="Break long words while wrapping. (default: %(default)s)",
+        action="store_true",
+    )
+    parser.add_argument(
+        "--no-replace-whitespace",
+        required=False,
+        help="Don't normalize whitespace when wrapping.",
+        action="store_false",
+    )
+    parser.add_argument(
+        "--no-reflow",
+        required=False,
+        help="Don't reflow lines.",
+        action="store_false",
+    )
+    parser.add_argument(
+        "--no-signoff",
+        required=False,
+        help="Don't preserve signoff line breaks.",
+        action="store_false",
+    )
+    parser.add_argument(
+        "--no-signature",
+        required=False,
+        help="Don't preserve signature block.",
+        action="store_false",
+    )
+    parser.add_argument(
+        "--no-squash",
+        required=False,
+        help="Don't squash consecutive paragraph breaks.",
+        action="store_false",
+    )
+    parser.add_argument(
+        "-i",
+        "--input",
+        required=False,
+        type=str,
+        default="STDIN",
+        help="Input file. (default: %(default)s)",
+    )
+    parser.add_argument(
+        "-o",
+        "--output",
+        required=False,
+        type=str,
+        default="STDOUT",
+        help="Output file. (default: %(default)s)",
+    )
+    args = parser.parse_args()
+    width = args.width
+    should_check_signoff = args.no_signoff
+    should_check_signature = args.no_signature
+    reflow = args.no_reflow
+    squash = args.no_squash
+    replace_whitespace = args.no_replace_whitespace
+    break_long_words = args.break_long_words
+
+    if args.input == "STDIN":
+        reader = sys.stdin
+    else:
+        with open(args.input, "r") as in_stream:
+            reader = in_stream
+    if args.output != "STDOUT":
+        out_stream = open(args.output, "w")
+
+    for line in reader:
+        line = line.rstrip()
+        if should_check_signoff:
+            is_signoff = check_signoff(line)
+            if is_signoff:
+                if not signoff_cache:
+                    signoff_cache = line
+                else:
+                    pprint(signoff_cache)
+                    pprint(line)
+                    signoff_cache = ""
+                continue
+            elif not is_signoff and signoff_cache:
+                paragraph.append(signoff_cache)
+                signoff_cache = ""
+        if line.startswith("```"):
+            flush_paragraph()
+            skipping = not skipping
+            pprint(line)
+        elif should_check_signature and line == "--":
+            flush_paragraph()
+            skipping = True
+            pprint("-- ")
+        elif not line or re.match(
+            r"^(\s+|-\s+|\+\s+|\*\s+|>\s*|#\s+|From:|To:|Cc:|Bcc:|Subject:|Reply-To:|In-Reply-To:|References:|Date:|Message-Id:|User-Agent:)",
+            line,
+        ):
+            flush_paragraph()
+            pprint(line)
+        elif skipping:
+            pprint(line)
+        else:
+            paragraph.append(line)
+    else:
+        if signoff_cache:
+            paragraph.append(signoff_cache)
+            signoff_cache = ""
+        flush_paragraph()
+    if out_stream is not None:
+        out_stream.close()
+
+# pyright: basic