#! /usr/bin/env python3
# encoding: utf-8
# Thomas Nagy, 2010-2015

import re
from waflib import Task, Logs
from waflib.TaskGen import extension

cy_api_pat = re.compile(r'\s*?cdef\s*?(public|api)\w*')
re_cyt = re.compile(r"""
	^\s*                           # must begin with some whitespace characters
	(?:from\s+(\w+)(?:\.\w+)*\s+)? # optionally match "from foo(.baz)" and capture foo
	c?import\s(\w+|[*])            # require "import bar" and capture bar
	""", re.M | re.VERBOSE)

@extension('.pyx')
def add_cython_file(self, node):
	"""
	Process a *.pyx* file given in the list of source files. No additional
	feature is required::

		def build(bld):
			bld(features='c cshlib pyext', source='main.c foo.pyx', target='app')
	"""
	ext = '.c'
	if 'cxx' in self.features:
		self.env.append_unique('CYTHONFLAGS', '--cplus')
		ext = '.cc'

	for x in getattr(self, 'cython_includes', []):
		# TODO re-use these nodes in "scan" below
		d = self.path.find_dir(x)
		if d:
			self.env.append_unique('CYTHONFLAGS', '-I%s' % d.abspath())

	tsk = self.create_task('cython', node, node.change_ext(ext))
	self.source += tsk.outputs

class cython(Task.Task):
	run_str = '${CYTHON} ${CYTHONFLAGS} -o ${TGT[0].abspath()} ${SRC}'
	color   = 'GREEN'

	vars    = ['INCLUDES']
	"""
	Rebuild whenever the INCLUDES change. The variables such as CYTHONFLAGS will be appended
	by the metaclass.
	"""

	ext_out = ['.h']
	"""
	The creation of a .h file is known only after the build has begun, so it is not
	possible to compute a build order just by looking at the task inputs/outputs.
	"""

	def runnable_status(self):
		"""
		Perform a double-check to add the headers created by cython
		to the output nodes. The scanner is executed only when the cython task
		must be executed (optimization).
		"""
		ret = super(cython, self).runnable_status()
		if ret == Task.ASK_LATER:
			return ret
		for x in self.generator.bld.raw_deps[self.uid()]:
			if x.startswith('header:'):
				self.outputs.append(self.inputs[0].parent.find_or_declare(x.replace('header:', '')))
		return super(cython, self).runnable_status()

	def post_run(self):
		for x in self.outputs:
			if x.name.endswith('.h'):
				if not x.exists():
					if Logs.verbose:
						Logs.warn('Expected %r', x.abspath())
					x.write('')
		return Task.Task.post_run(self)

	def scan(self):
		"""
		Return the dependent files (.pxd) by looking in the include folders.
		Put the headers to generate in the custom list "bld.raw_deps".
		To inspect the scanne results use::

			$ waf clean build --zones=deps
		"""
		node = self.inputs[0]
		txt = node.read()

		mods = set()
		for m in re_cyt.finditer(txt):
			if m.group(1):  # matches "from foo import bar"
				mods.add(m.group(1))
			else:
				mods.add(m.group(2))

		Logs.debug('cython: mods %r', mods)
		incs = getattr(self.generator, 'cython_includes', [])
		incs = [self.generator.path.find_dir(x) for x in incs]
		incs.append(node.parent)

		found = []
		missing = []
		for x in sorted(mods):
			for y in incs:
				k = y.find_resource(x + '.pxd')
				if k:
					found.append(k)
					break
			else:
				missing.append(x)

		# the cython file implicitly depends on a pxd file that might be present
		implicit = node.parent.find_resource(node.name[:-3] + 'pxd')
		if implicit:
			found.append(implicit)

		Logs.debug('cython: found %r', found)

		# Now the .h created - store them in bld.raw_deps for later use
		has_api = False
		has_public = False
		for l in txt.splitlines():
			if cy_api_pat.match(l):
				if ' api ' in l:
					has_api = True
				if ' public ' in l:
					has_public = True
		name = node.name.replace('.pyx', '')
		if has_api:
			missing.append('header:%s_api.h' % name)
		if has_public:
			missing.append('header:%s.h' % name)

		return (found, missing)

def options(ctx):
	ctx.add_option('--cython-flags', action='store', default='', help='space separated list of flags to pass to cython')

def configure(ctx):
	if not ctx.env.CC and not ctx.env.CXX:
		ctx.fatal('Load a C/C++ compiler first')
	if not ctx.env.PYTHON:
		ctx.fatal('Load the python tool first!')
	ctx.find_program('cython', var='CYTHON')
	if hasattr(ctx.options, 'cython_flags'):
		ctx.env.CYTHONFLAGS = ctx.options.cython_flags

