markdown

cht/ui/markdown.py

@@ -0,0 +1,145 @@
+"""Markdown → Gtk.TextBuffer renderer.
+
+Pure functions — no app state, just TextBuffer + TextIter operations.
+"""
+
+import re
+
+from gi.repository import Gtk
+
+
+def setup_tags(buf: Gtk.TextBuffer) -> None:
+    """Create the standard set of text tags used by render()."""
+    buf.create_tag("h1", weight=700, scale=1.4)
+    buf.create_tag("h2", weight=700, scale=1.2)
+    buf.create_tag("h3", weight=700, scale=1.05)
+    buf.create_tag("bold", weight=700)
+    buf.create_tag("italic", style=2)
+    buf.create_tag("code", family="monospace", background="#2a2a2a", foreground="#e8e8e8")
+    buf.create_tag("codeblock", family="monospace", background="#1e1e1e",
+                   foreground="#e8e8e8", left_margin=16, right_margin=16,
+                   pixels_above_lines=4, pixels_below_lines=4)
+    buf.create_tag("bullet", left_margin=16)
+
+
+def render(buf: Gtk.TextBuffer, insert_iter: Gtk.TextIter, text: str) -> None:
+    """Parse *text* as lightweight Markdown and insert into *buf* at *insert_iter*."""
+    lines = text.split("\n")
+    i = 0
+    while i < len(lines):
+        line = lines[i]
+        if line.startswith("```"):
+            lang = line[3:].strip()
+            block_lines = []
+            i += 1
+            while i < len(lines) and not lines[i].startswith("```"):
+                block_lines.append(lines[i])
+                i += 1
+            code = "\n".join(block_lines) + "\n"
+            block_mark = buf.create_mark(None, insert_iter, True)
+            _insert_highlighted_code(buf, insert_iter, code, lang)
+            buf.apply_tag_by_name("codeblock", buf.get_iter_at_mark(block_mark), insert_iter)
+            buf.delete_mark(block_mark)
+            buf.insert(insert_iter, "\n")
+            i += 1
+            continue
+        header_match = re.match(r"^(#{1,3})\s+(.*)", line)
+        if header_match:
+            level = len(header_match.group(1))
+            content = header_match.group(2)
+            tag = f"h{level}"
+            mark = buf.create_mark(None, insert_iter, True)
+            buf.insert(insert_iter, content + "\n")
+            buf.apply_tag_by_name(tag, buf.get_iter_at_mark(mark), insert_iter)
+            i += 1
+            continue
+        bullet_match = re.match(r"^[\-\*]\s+(.*)", line)
+        if bullet_match:
+            _insert_inline(buf, insert_iter, "• " + bullet_match.group(1), "bullet")
+            buf.insert(insert_iter, "\n")
+            i += 1
+            continue
+        _insert_inline_line(buf, insert_iter, line)
+        buf.insert(insert_iter, "\n")
+        i += 1
+
+
+# -- private helpers --
+
+_INLINE_RE = re.compile(
+    r"(\*\*(.+?)\*\*|__(.+?)__|"
+    r"\*(.+?)\*|_(.+?)_|"
+    r"`([^`]+?)`)"
+)
+
+
+def _insert_inline(buf, it, text: str, outer_tag: str | None = None):
+    mark = buf.create_mark(None, it, True)
+    _insert_inline_line(buf, it, text)
+    if outer_tag:
+        buf.apply_tag_by_name(outer_tag, buf.get_iter_at_mark(mark), it)
+
+
+def _insert_inline_line(buf, it, text: str):
+    pos = 0
+    for m in _INLINE_RE.finditer(text):
+        if m.start() > pos:
+            buf.insert(it, text[pos:m.start()])
+        full = m.group(0)
+        if full.startswith("**") or full.startswith("__"):
+            inner = m.group(2) or m.group(3)
+            mark = buf.create_mark(None, it, True)
+            buf.insert(it, inner)
+            buf.apply_tag_by_name("bold", buf.get_iter_at_mark(mark), it)
+        elif full.startswith("*") or full.startswith("_"):
+            inner = m.group(4) or m.group(5)
+            mark = buf.create_mark(None, it, True)
+            buf.insert(it, inner)
+            buf.apply_tag_by_name("italic", buf.get_iter_at_mark(mark), it)
+        elif full.startswith("`"):
+            inner = m.group(6)
+            mark = buf.create_mark(None, it, True)
+            buf.insert(it, inner)
+            buf.apply_tag_by_name("code", buf.get_iter_at_mark(mark), it)
+        pos = m.end()
+    if pos < len(text):
+        buf.insert(it, text[pos:])
+
+
+def _insert_highlighted_code(buf, it, code: str, lang: str):
+    try:
+        from pygments.lexers import get_lexer_by_name, guess_lexer
+        from pygments.styles import get_style_by_name
+    except ImportError:
+        buf.insert(it, code)
+        return
+    try:
+        lexer = get_lexer_by_name(lang, stripall=False) if lang else guess_lexer(code)
+    except Exception:
+        try:
+            lexer = guess_lexer(code)
+        except Exception:
+            buf.insert(it, code)
+            return
+    try:
+        style = get_style_by_name("monokai")
+    except Exception:
+        buf.insert(it, code)
+        return
+    tag_table = buf.get_tag_table()
+    for ttype, value in lexer.get_tokens(code):
+        tag_name = f"pyg_{ttype}"
+        tag = tag_table.lookup(tag_name)
+        if tag is None:
+            sf = style.style_for_token(ttype)
+            tag = buf.create_tag(tag_name, family="monospace")
+            if sf.get("color"):
+                tag.set_property("foreground", f"#{sf['color']}")
+            if sf.get("bold"):
+                tag.set_property("weight", 700)
+            if sf.get("italic"):
+                tag.set_property("style", 2)
+        mark = buf.create_mark(None, it, True)
+        buf.insert(it, value)
+        buf.apply_tag(tag, buf.get_iter_at_mark(mark), it)
+        buf.delete_mark(mark)