🐛 FIX: reorder footnotes (#23)

Author: KyleKing

mdformat_footnote/__init__.py

@@ -1,5 +1,6 @@
 """An mdformat plugin for parsing/validating footnotes"""
 
 __version__ = "0.1.2"
+__plugin_name__ = "footnote"
 
-from .plugin import RENDERERS, update_mdit  # noqa: F401
+from .plugin import RENDERERS, add_cli_argument_group, update_mdit  # noqa: F401

mdformat_footnote/_helpers.py

@@ -0,0 +1,17 @@
+"""Helper functions for plugin configuration."""
+
+from __future__ import annotations
+
+from collections.abc import Mapping
+from typing import Any
+
+from . import __plugin_name__
+
+ContextOptions = Mapping[str, Any]
+
+
+def get_conf(options: ContextOptions, key: str) -> bool | str | int | None:
+    """Read setting from mdformat configuration Context."""
+    if (api := options["mdformat"].get(key)) is not None:
+        return api
+    return options["mdformat"].get("plugin", {}).get(__plugin_name__, {}).get(key)

mdformat_footnote/_reorder.py

@@ -0,0 +1,285 @@
+"""Footnote ID and subId normalization logic."""
+
+from __future__ import annotations
+
+from dataclasses import dataclass, field
+import re
+
+from markdown_it.rules_core import StateCore
+
+_FOOTNOTE_REF_PATTERN = re.compile(r"\[\^([^\]]+)\]")
+
+
+@dataclass
+class _FootnoteCategories:
+    """Categorized footnotes for reordering."""
+
+    body_referenced: list[tuple[int, str, str]]
+    nested_only: set[str]
+    fence_only: list[str]
+    true_orphans: list[str]
+
+    @property
+    def body_labels(self) -> set[str]:
+        return {label for _, _, label in self.body_referenced}
+
+
+@dataclass
+class _ReorderState:
+    """Mutable state for footnote reordering."""
+
+    old_list: dict
+    refs: dict
+    new_list: dict = field(default_factory=dict)
+    old_to_new_id: dict[int, int] = field(default_factory=dict)
+    processed: set[str] = field(default_factory=set)
+    new_id: int = 0
+
+    def _find_def_by_label(self, label: str) -> dict:
+        for fn_data in self.old_list.values():
+            if fn_data.get("label") == label:
+                return fn_data.copy()
+        return {"label": label, "count": 0}
+
+    def _find_old_id_by_label(self, label: str) -> int | None:
+        for old_id, fn_data in self.old_list.items():
+            if fn_data.get("label") == label:
+                return old_id
+        return None
+
+    def add_footnote(
+        self, label: str, label_key: str, old_id: int | None = None
+    ) -> None:
+        """Add a footnote to the new list and update mappings."""
+        if label in self.processed:
+            return
+
+        self.new_list[self.new_id] = self._find_def_by_label(label)
+
+        effective_old_id = old_id or self._find_old_id_by_label(label)
+        if effective_old_id is not None:
+            self.old_to_new_id[effective_old_id] = self.new_id
+
+        self.refs[label_key] = self.new_id
+        self.processed.add(label)
+        self.new_id += 1
+
+
+def _collect_refs_in_fences(tokens: list) -> list[str]:
+    """Collect footnote labels referenced in fence tokens, preserving order."""
+    refs: list[str] = []
+    seen: set[str] = set()
+    for token in tokens:
+        if token.type != "fence" or not token.content:
+            continue
+        for match in _FOOTNOTE_REF_PATTERN.finditer(token.content):
+            label = match.group(1)
+            if label not in seen:
+                refs.append(label)
+                seen.add(label)
+    return refs
+
+
+def _build_dependency_graph(tokens: list) -> dict[str, set[str]]:
+    """Build a graph of which footnotes reference which others."""
+    graph: dict[str, set[str]] = {}
+    current_def_label: str | None = None
+
+    for token in tokens:
+        match token.type:
+            case "footnote_reference_open":
+                current_def_label = token.meta.get("label")
+                if current_def_label:
+                    graph.setdefault(current_def_label, set())
+            case "footnote_reference_close":
+                current_def_label = None
+            case _ if current_def_label is not None:
+                _collect_nested_refs(token, graph[current_def_label])
+
+    return graph
+
+
+def _collect_nested_refs(token, ref_set: set[str]) -> None:
+    """Collect footnote labels referenced from a token and its children."""
+    if token.type == "footnote_ref" and token.meta:
+        ref_set.add(token.meta["label"])
+    for child in token.children or []:
+        _collect_nested_refs(child, ref_set)
+
+
+def _categorize_footnotes(
+    refs: dict,
+    footnote_deps: dict[str, set[str]],
+    refs_in_fences: list[str],
+) -> _FootnoteCategories:
+    """Categorize footnotes."""
+    referenced_by_footnotes: set[str] = set()
+    for refs_set in footnote_deps.values():
+        referenced_by_footnotes.update(refs_set)
+
+    refs_in_fences_set = set(refs_in_fences)
+
+    body_referenced: list[tuple[int, str, str]] = []
+    nested_only: set[str] = set()
+    fence_only_set: set[str] = set()
+    true_orphans: list[str] = []
+
+    for label_key, old_id in refs.items():
+        label = label_key[1:]
+        match (
+            old_id >= 0,
+            label in referenced_by_footnotes,
+            label in refs_in_fences_set,
+        ):
+            case (True, _, _):
+                body_referenced.append((old_id, label_key, label))
+            case (False, True, _):
+                nested_only.add(label)
+            case (False, False, True):
+                fence_only_set.add(label)
+            case _:
+                true_orphans.append(label_key)
+
+    body_referenced.sort(key=lambda x: x[0])
+    fence_only = [label for label in refs_in_fences if label in fence_only_set]
+
+    return _FootnoteCategories(body_referenced, nested_only, fence_only, true_orphans)
+
+
+def _process_nested_for_parent(
+    parent_label: str,
+    footnote_deps: dict[str, set[str]],
+    state: _ReorderState,
+    skip_labels: set[str],
+) -> None:
+    """Process nested footnotes referenced by a parent footnote."""
+    for nested_label in footnote_deps.get(parent_label, []):
+        if nested_label not in skip_labels:
+            state.add_footnote(nested_label, f":{nested_label}")
+
+
+def _build_reordered_list(
+    categories: _FootnoteCategories,
+    footnote_deps: dict[str, set[str]],
+    old_list: dict,
+    refs: dict,
+    keep_orphans: bool,
+) -> _ReorderState:
+    """Build the reordered footnote list from categorized footnotes."""
+    state = _ReorderState(old_list=old_list, refs=refs)
+    skip_labels = categories.body_labels | set(categories.true_orphans)
+
+    for old_id, label_key, label in categories.body_referenced:
+        state.add_footnote(label, label_key, old_id)
+        _process_nested_for_parent(label, footnote_deps, state, skip_labels)
+
+    for nested_label in categories.nested_only:
+        state.add_footnote(nested_label, f":{nested_label}")
+
+    for fence_label in categories.fence_only:
+        state.add_footnote(fence_label, f":{fence_label}")
+
+    if keep_orphans:
+        for orphan_key in categories.true_orphans:
+            state.add_footnote(orphan_key[1:], orphan_key)
+
+    return state
+
+
+def _update_token_ids(tokens: list, old_to_new_id: dict[int, int]) -> None:
+    """Recursively update footnote IDs in tokens."""
+    for token in tokens:
+        if token.type in ("footnote_ref", "footnote_anchor"):
+            if token.meta and (old_id := token.meta.get("id")) in old_to_new_id:
+                token.meta["id"] = old_to_new_id[old_id]
+        for child in token.children or []:
+            _update_token_ids([child], old_to_new_id)
+
+
+def _partition_refs_by_context(tokens: list) -> tuple[list, dict[str, list]]:
+    """Partition footnote refs into body refs and definition refs."""
+    body_refs: list = []
+    def_refs: dict[str, list] = {}
+    current_def_label: str | None = None
+
+    for token in tokens:
+        match token.type:
+            case "footnote_reference_open":
+                current_def_label = token.meta.get("label")
+                if current_def_label:
+                    def_refs.setdefault(current_def_label, [])
+            case "footnote_reference_close":
+                current_def_label = None
+            case _ if current_def_label is None:
+                _collect_refs(token, body_refs)
+            case _:
+                _collect_refs(token, def_refs.setdefault(current_def_label, []))
+
+    return body_refs, def_refs
+
+
+def _assign_subids_to_refs(ref_tokens: list, counters: dict[int, int]) -> None:
+    """Assign sequential subIds to a list of ref tokens."""
+    for ref_token in ref_tokens:
+        fn_id = ref_token.meta["id"]
+        ref_token.meta["subId"] = counters.get(fn_id, 0)
+        counters[fn_id] = counters.get(fn_id, 0) + 1
+
+
+def _reassign_subids(tokens: list, refs: dict, footnote_list: dict) -> None:
+    """Reassign subIds based on output order: body refs first, then definition refs."""
+    body_refs, def_refs = _partition_refs_by_context(tokens)
+    subid_counters: dict[int, int] = {}
+
+    _assign_subids_to_refs(body_refs, subid_counters)
+
+    for label_key in refs:
+        label = label_key[1:]
+        if label in def_refs:
+            _assign_subids_to_refs(def_refs[label], subid_counters)
+
+    for fn_id, count in subid_counters.items():
+        if fn_id in footnote_list:
+            footnote_list[fn_id]["count"] = count
+
+
+def _collect_refs(token, ref_list: list) -> None:
+    """Collect footnote_ref tokens from a token and its children."""
+    if token.type == "footnote_ref" and token.meta:
+        ref_list.append(token)
+    for child in token.children or []:
+        _collect_refs(child, ref_list)
+
+
+def _get_footnote_data(state: StateCore) -> tuple[dict, dict] | None:
+    """Extract footnote refs and list from state, or None if missing."""
+    footnote_data = state.env.get("footnotes", {})
+    refs = footnote_data.get("refs", {})
+    if not refs:
+        return None
+    return refs, footnote_data.get("list", {})
+
+
+def reorder_footnotes_by_definition(
+    state: StateCore, keep_orphans: bool = False
+) -> None:
+    """Reorder footnotes by reference order, fix IDs, and handle orphans."""
+    if (data := _get_footnote_data(state)) is None:
+        return
+
+    refs, old_list = data
+    footnote_deps = _build_dependency_graph(state.tokens)
+    refs_in_fences = _collect_refs_in_fences(state.tokens)
+    categories = _categorize_footnotes(refs, footnote_deps, refs_in_fences)
+
+    if not keep_orphans:
+        for orphan_key in categories.true_orphans:
+            del refs[orphan_key]
+
+    reorder_state = _build_reordered_list(
+        categories, footnote_deps, old_list, refs, keep_orphans
+    )
+
+    state.env["footnotes"]["list"] = reorder_state.new_list
+    _update_token_ids(state.tokens, reorder_state.old_to_new_id)
+    _reassign_subids(state.tokens, refs, reorder_state.new_list)

mdformat_footnote/plugin.py

@@ -1,20 +1,52 @@
 from __future__ import annotations
 
+import argparse
 from collections.abc import Mapping
+from functools import partial
 import textwrap
 
 from markdown_it import MarkdownIt
 from mdformat.renderer import RenderContext, RenderTreeNode
 from mdformat.renderer.typing import Render
 from mdit_py_plugins.footnote import footnote_plugin
 
+from ._helpers import ContextOptions, get_conf
+from ._reorder import reorder_footnotes_by_definition
+
+
+def _keep_orphans(options: ContextOptions) -> bool:
+    """Check if orphan footnotes should be preserved."""
+    return bool(get_conf(options, "keep_orphans")) or False
+
+
+def add_cli_argument_group(group: argparse._ArgumentGroup) -> None:
+    """Add options to the mdformat CLI.
+
+    Stored in `mdit.options["mdformat"]["plugin"]["footnote"]`
+    """
+    group.add_argument(
+        "--keep-footnote-orphans",
+        action="store_const",
+        const=True,
+        dest="keep_orphans",
+        help=(
+            "Keep footnote definitions that are never referenced "
+            "(default: remove them)"
+        ),
+    )
+
 
 def update_mdit(mdit: MarkdownIt) -> None:
     """Update the parser, adding the footnote plugin."""
     mdit.use(footnote_plugin)
     # Disable inline footnotes for now, since we don't have rendering
     # support for them yet.
     mdit.disable("footnote_inline")
+    # Reorder footnotes by reference order, fix IDs, and handle orphans.
+    # Must run before footnote_tail.
+    keep_orphans = _keep_orphans(mdit.options)
+    reorder_fn = partial(reorder_footnotes_by_definition, keep_orphans=keep_orphans)
+    mdit.core.ruler.before("footnote_tail", "reorder_footnotes", reorder_fn)
 
 
 def _footnote_ref_renderer(node: RenderTreeNode, context: RenderContext) -> str:

tests/fixture_helpers.py

@@ -0,0 +1,23 @@
+"""Helper utilities for loading test fixtures."""
+
+from pathlib import Path
+
+from markdown_it.utils import read_fixture_file
+
+
+def load_fixtures(filename: str) -> list[tuple[int, str, str, str]]:
+    """Load fixtures from a file in tests/fixtures/ directory."""
+    fixture_path = Path(__file__).parent / "fixtures" / filename
+    return read_fixture_file(fixture_path)
+
+
+def get_fixture(filename: str, title: str) -> tuple[str, str]:
+    """Get a specific fixture by title from a file."""
+    fixtures = load_fixtures(filename)
+    for _, fixture_title, input_text, expected_output in fixtures:
+        if fixture_title == title:
+            return input_text, expected_output
+    available = [f[1] for f in fixtures]
+    raise ValueError(
+        f"Fixture '{title}' not found in {filename}. Available: {available}"
+    )