from panflute import *
import re

# Import local files
from whitespace import *
from command import *
from util import *
from context import *

def transform(e: Element, c: Context) -> Element: # Returns next sibling element to transform
	"""Transform the AST, making format-agnostic changes."""
	
	if isinstance(e, Whitespace) and bavlna(e, c):
		e = NBSP()

	if hasattr(e, "attributes"):
		# `if` attribute. Only show this element if flag is set.
		if "if" in e.attributes:
			if not c.is_flag_set(e.attributes["if"]):
				return nullify(e)
		# `ifn` attribute. Only show this element if flag is NOT set
		if "ifn" in e.attributes:
			if c.is_flag_set(e.attributes["ifn"]):
				return nullify(e)

		# `c` attribute. Execute a command with the name saved in this attribute.
		if (isinstance(e, Div) or isinstance(e, Span)) and "c" in e.attributes:
			if isinstance(e, Div):
				e = BlockCommand(*e.content, identifier=e.identifier, classes=e.classes, attributes=e.attributes)
			else:
				e = InlineCommand(*e.content, identifier=e.identifier, classes=e.classes, attributes=e.attributes)

		# `partial` attribute.
		# This is for including content from files with their own flags and
		# commands without affecting the state of the current document.
		if (isinstance(e, Div)) and "partial" in e.attributes:
			includedDoc = import_md(open(e.attributes["partial"], "r").read())
			nContext = Context(includedDoc, c)
			includedDoc = includedDoc.walk(transform, nContext)
			e = Div(*includedDoc.content)

	# Execute python code inside source code block
	if isinstance(e, CodeBlock) and hasattr(e, "classes") and "python" in e.classes and "run" in e.classes:
		e = executeCommand(e.text, None, c)

	## Command defines
	# possible TODO: def/longdef?
	if isinstance(e, CodeBlock) and hasattr(e, "classes") and "python" in e.classes and hasattr(e, "attributes"):
		e = handle_command_define(e, c)

	## Shorthands
	if isinstance(e, Span) and len(e.content) == 1 and isinstance(e.content[0], Str):
		## Handle special command shorthand [!commandname]{}
		if re.match(r"^![\w.]+$", e.content[0].text):
			e = InlineCommand(identifier=e.identifier, classes=e.classes, attributes={**e.attributes, "c": e.content[0].text[1:]})

		## Handle import [#path/file.md]{}
		# This is the exact opposite of include. We take the commands
		# and flags but drop the content.
		elif re.match(r"^#.+$", e.content[0].text):
			importedDoc = import_md(open(e.content[0].text[1:], "r").read())
			importedDoc.walk(transform, c)
			return nullify(e)

	## Execute commands
	# panflute's walk transforms the children first, then the root element, so
	# the content of the element the command receives is already transformed.
	if isinstance(e, Command):
		if not c.get_command(e.attributes["c"]):
			raise NameError(f"Command not defined '{e.attributes['c']}'.")
		e = e.replaceSelf(executeCommand(c.get_command(e.attributes["c"]), e, c))
		e.walk(transform, c)

	return e