md2txt/README.md

# md2amb utilities

This repository contains command line helpers for transforming Markdown into formats that work well on retro hardware or constrained text viewers. A small plugin API lets you mix-and-match parsers and renderers so additional formats can plug into the same preprocessing pipeline.

## Tools

- `md2amb.py` – converts Markdown into Amber-screen formatted text (see script for details).
- `md2txt.py` – converts Markdown into 80-column, DOS-compatible plain text with extensive formatting support. It ships with the default `markdown` parser and `text` renderer plugins, registers an optional `micron` renderer for Micron-formatted output, and exposes the core pipeline so you can add your own parser or renderer modules:
  - FIGlet-rendered headings (H1–H3) driven by optional YAML frontmatter (`h1_font`, `h2_font`, `h3_font`).
  - H4+ headings rendered in uppercase with dashed underlines.
  - Emphasis styles converted to spaced or delimited characters, e.g. `**bold**` → `B O L D`, `__strong__` → `_s_t_r_o_n_g_`, `~~strike~~` → `~s~t~r~i~k~e~`.
  - Blockquotes prefixed by `|    `, lists preserved, inline code untouched.
  - Code blocks numbered (`01 | line`), with both fenced and indented fences supported (see “Rendering Controls” for customisation).
  - Links transformed into `[label](n)` references, with footnote-style URL list at the end.
  - Optional alignment and margin controls via HTML `<p>` attributes or MultiMarkdown attribute blocks (e.g. `{:.center margin=20px}`) applied as leading spaces.
  - Recursive file includes using `![[file.md]]` or `{.include file.md}` (frontmatter inside the included file is ignored).
  - ASCII art injection with `#[label :align](art.txt)` syntax, supporting multiple art pieces per line and optional `{: .right}` style annotations.
  - Per-document toggles for code block wrapping, numbering, blockquote decoration, and list indentation spacing.

## Requirements

- Python 3.9+.
- Optional: `PyHyphen` (preferred) or `pyphen` for dictionary-driven hyphenation.
- Optional: `pyfiglet` for FIGlet headings (`pip install pyfiglet`). When unavailable, headings fall back to the H4-style renderer automatically.

## Usage

```bash
python md2txt.py input.md -o output.txt                         # convert to DOS-friendly text
python md2txt.py input.md                                      # write result to stdout
python md2txt.py input.md --width 72                           # override column width
python md2txt.py input.md --parser markdown --renderer micron  # emit Micron-formatted output
python md2txt.py input.md --renderer-option width=68           # pass KEY=VALUE to a renderer
```

`--parser` and `--renderer` select a plugin by name (defaults are `markdown` and `text`). Repeatable `--parser-option KEY=VALUE` and `--renderer-option KEY=VALUE` pairs are forwarded to the plugin factories as keyword arguments in addition to the defaults supplied by the CLI. Both scripts accept `--help` for the full option list.

## FIGlet Fonts via Frontmatter

You can set FIGlet fonts for H1–H3 per document using YAML frontmatter:

```markdown
---
h1_font: slant
h2_font: standard
h3_font: small
margin_left: 4
margin_right: 4
hyphenate: true
hyphen_lang: en_US
---

# Main Title
## Section Heading
### Subsection
```

Font names also accept the special keywords `caps` (force uppercase) and `title` (title case) for any heading. `margin_left` and `margin_right` add leading/trailing spaces to body text, `paragraph_spacing` (or `lines_between_paragraphs`) inserts blank lines between paragraphs, enabling `hyphenate` activates PyHyphen-based wrapping (optional `hyphen_lang` defaults to `en_US`), and `header_spacing` controls how many blank lines precede headings (default `2`). Set `figlet_fallback: true` to force an H4-style fallback when a FIGlet banner would overflow; when omitted (the default), the banner is kept even if it extends beyond the width.

## Styling via Attribute Blocks

You can influence alignment and margins in the source Markdown using either HTML paragraphs or MultiMarkdown attribute blocks:

```markdown
<p align="center" style="margin: 10px 20px;">
Centered paragraph with custom margins.
</p>

Paragraph styled via MMD attributes.
{: .right margin=12px }

## Centered Heading {: .center margin=8px }
```

Margins are interpreted as spaces; values using `px` are rounded to the nearest integer, and `margin: 0 auto;` centers content.

## File Includes

Two lightweight include syntaxes are recognised during preprocessing:

- `![[relative/path.md]]`
- `{.include relative/path.md}`

The paths are resolved relative to the file that contains the directive. Any YAML frontmatter in the included file is stripped before inlining, and include cycles are detected and rejected.

## ASCII Art Blocks

Inline or block-level ASCII art can be embedded directly in Markdown:

```markdown
#[dragon :left](examples/dragon.txt)
#[dragon :right](examples/dragon.txt){:.center}
#[dragon_a :left](a.txt) #[dragon_b :center](b.txt) #[dragon_c :right](c.txt)
```

- `#[label](file)` loads the contents of the text file and inserts it as a preformatted block.
- Colon tags inside the label (`:left`, `:center`, `:right`) steer the alignment of each art piece. Additional colon tags are ignored.
- When multiple directives appear on the same line, the pieces are laid out side-by-side when space permits, otherwise they fall back to stacked blocks.
- A trailing MultiMarkdown attribute block (e.g. `{:.center}`) is applied to the combined block after the art has been injected.

## Rendering Controls via Frontmatter

Fine-tune formatting by adding keys to frontmatter:

| Key | Description |
| --- | --- |
| `wrap_code_blocks: true` | Wrap fenced/indented code blocks to fit the page width instead of using a gutter. |
| `code_block_wrap: <bool or int>` | Enables wrapping; when set to an integer it also controls the extra indentation applied to wrapped continuation lines. |
| `code_block_line_numbers: false` | Disable the `01 |` gutter in wrapped or unwrapped code blocks. |
| `blockquote_bars: false` | Replace the default `|` prefix with three spaces. |
| `list_marker_indent: <int>` | Extra spaces inserted before list markers. |
| `list_text_spacing: <int>` | Spaces between the marker and the wrapped list text. |

All values are optional—defaults maintain the legacy behaviour.

## Output Line Endings

Generated text uses CRLF line endings to maintain DOS compatibility.

## Plugin Architecture

The conversion pipeline lives in `conversion_core.py` and is exposed via `run_conversion`. It is designed around lightweight factories:

- **Parser factories** receive `base_style: BlockStyle` plus any extra keyword arguments and must return an object with a `parse(lines: Iterable[str]) -> Iterator[BlockEvent | StyleUpdateEvent]` method. The bundled `MarkdownParser` implements this interface.
- **Renderer factories** receive `frontmatter: FrontMatter` and arbitrary keyword arguments and must return an object that provides `handle_event(event)` and `finalize() -> Any`. The `TextRenderer` returns a list of DOS-friendly output lines; other renderers may return any data appropriate for their target format.

Plugins register themselves through the helpers in `plugins.py`:

```python
from plugins import register_parser, register_renderer

def my_parser_factory(*, base_style, **options):
    return MyParser(base_style, **options)

register_parser("my-markdown", my_parser_factory)
```

```python
def my_renderer_factory(*, frontmatter, **options):
    return MyRenderer(frontmatter, target=options.get("target"))

register_renderer("ansi", my_renderer_factory)
```

Once registered (for example in a small module that imports `md2txt.py`), the new plugins are available via `--parser my-markdown` or `--renderer ansi`. The CLI lists registered plugin names in `--help`, and the helper functions `available_parsers()` / `available_renderers()` return the sorted names if you need to build higher-level tooling.

The shared preprocessing helpers—YAML frontmatter parsing, recursive include expansion, and ASCII art sentinels—also live in `conversion_core.py`, allowing alternate front-ends to reuse exactly the same behaviour without duplicating code.