From a9f15f5879f6f43a779af8ba5f20c957050aaac2 Mon Sep 17 00:00:00 2001
From: Archmonger <16909269+Archmonger@users.noreply.github.com>
Date: Fri, 9 Feb 2024 19:26:13 -0800
Subject: [PATCH] Link Django CSS to components (CSS Modules)

---
 requirements/pkg-deps.txt         |   1 +
 src/reactpy_django/css_modules.py | 124 ++++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+)
 create mode 100644 src/reactpy_django/css_modules.py

diff --git a/requirements/pkg-deps.txt b/requirements/pkg-deps.txt
index c6102c18..e49f12d9 100644
--- a/requirements/pkg-deps.txt
+++ b/requirements/pkg-deps.txt
@@ -7,3 +7,4 @@ dill >=0.3.5
 orjson >=3.6.0
 nest_asyncio >=1.5.0
 typing_extensions
+tinycss2 >=1.0.2
diff --git a/src/reactpy_django/css_modules.py b/src/reactpy_django/css_modules.py
new file mode 100644
index 00000000..e9263399
--- /dev/null
+++ b/src/reactpy_django/css_modules.py
@@ -0,0 +1,124 @@
+import re
+from dataclasses import dataclass, field
+from typing import Any, Literal, TypedDict
+
+import tinycss2
+from tinycss2.ast import QualifiedRule
+
+file_text = open("example.css", "r").read()
+
+
+SquareBracketValues = TypedDict(
+    "SquareBracketValues",
+    {"key": str, "operator": str | None, "value": str | list | None},
+)
+
+
+@dataclass
+class CssRule:
+    """Represents a CSS selector.
+    Examples of the parser's targets are shown below as docstrings."""
+
+    tag: str | Literal["*"] | None = None
+    """div, span"""
+    id: str | None = None
+    """#id1, #id2"""
+    classes: list[str] = field(default_factory=list)
+    """.class1, .class2"""
+    attributes: list[SquareBracketValues] = field(default_factory=list)
+    """[key=value], [key^=value]"""
+    styles: dict[str, Any] = field(default_factory=dict)
+    """color: red;"""
+    psuedo_functions: list[str] = field(default_factory=list)
+    """:not(), :nth-child()"""
+    psuedo_elements: list[str] = field(default_factory=list)
+    """:hover, :focus"""
+    psuedo_classes: list[str] = field(default_factory=list)
+    """::before, ::after"""
+
+    next: list["CssRule"] = field(default_factory=list)
+    """#current-selector #next-selector"""
+    next_operator: str = " "
+    """>, +, ~"""
+
+
+@dataclass
+class CssToPython:
+    """Performs a best-effort conversion of a CSS file into a list of Python dictionaries."""
+
+    content: str
+
+    def convert(self) -> list[CssRule]:
+        """Converts the CSS file into a list of CSS rule dictionaries."""
+        self.parsed: list[QualifiedRule] = tinycss2.parse_stylesheet(
+            self.content,
+            skip_comments=True,
+            skip_whitespace=True,
+        )
+        self.selectors: list[CssRule] = []
+
+        for style in self.parsed:
+            if style.type != "qualified-rule":
+                continue
+            selector = CssRule()
+
+            # Determine what CSS rules are defined in the selector
+            computed_rules = tinycss2.parse_declaration_list(
+                style.content, skip_comments=True, skip_whitespace=True
+            )
+            for rule in computed_rules:
+                selector.styles[rule.name] = self._parse_rule_value(rule.value)
+
+            # Parse HTML tag name from the selector
+            if style.prelude[0].type == "ident":
+                selector.tag = style.prelude[0].value
+            elif style.prelude[0].type == "literal" and style.prelude[0].value == "*":
+                selector.tag = "*"
+
+            # Parse all other attributes from the selector
+            print(style.prelude)
+            for count, token in enumerate(style.prelude):
+                if token.type == "hash":
+                    selector.id = selector.id or token.value
+                elif token.type == "literal" and token.value == ".":
+                    selector.classes.append(style.prelude[count + 1].value)
+                elif token.type == "[] block" and len(token.content) == 1:
+                    selector.attributes.append(
+                        {
+                            "key": token.content[0].value,
+                            "operator": None,
+                            "value": None,
+                        }
+                    )
+                elif token.type == "[] block" and len(token.content) == 3:
+                    selector.attributes.append(
+                        {
+                            "key": token.content[0].value,
+                            "operator": token.content[1].value,
+                            "value": token.content[2].value,
+                        }
+                    )
+                # TODO: Once we reach an operator or whitespace, recursively parse the children then break
+                # TODO: Split comma operators into separate selectors
+
+            self.selectors.append(selector)
+
+        return self.selectors
+
+    @staticmethod
+    def _flatten_whitespace(string: str) -> str:
+        return re.sub(r"\s+", " ", string).strip()
+
+    def _parse_rule_value(self, rule):
+        """Parses a single TinyCSS rule and returns Python a data type."""
+        rule = tinycss2.serialize(rule)
+        rule = self._flatten_whitespace(rule)
+        if rule.isnumeric():
+            return int(rule)
+        else:
+            return rule
+
+
+styles = CssToPython(file_text).convert()
+for style in styles:
+    print(style)