#!/usr/bin/env python
# encoding: utf-8
# Copyright Garmin International or its subsidiaries, 2012-2013

'''
Off-load dependency scanning from Python code to MSVC compiler

This tool is safe to load in any environment; it will only activate the
MSVC exploits when it finds that a particular taskgen uses MSVC to
compile.

Empirical testing shows about a 10% execution time savings from using
this tool as compared to c_preproc.

The technique of gutting scan() and pushing the dependency calculation
down to post_run() is cribbed from gccdeps.py.

This affects the cxx class, so make sure to load Qt5 after this tool.

Usage::

	def options(opt):
		opt.load('compiler_cxx')
	def configure(conf):
		conf.load('compiler_cxx msvcdeps')
'''

import os, sys, tempfile, threading

from waflib import Context, Errors, Logs, Task, Utils
from waflib.Tools import c_preproc, c, cxx, msvc
from waflib.TaskGen import feature, before_method

lock = threading.Lock()
nodes = {} # Cache the path -> Node lookup

PREPROCESSOR_FLAG = '/showIncludes'
INCLUDE_PATTERN = 'Note: including file:'

# Extensible by outside tools
supported_compilers = ['msvc']

@feature('c', 'cxx')
@before_method('process_source')
def apply_msvcdeps_flags(taskgen):
	if taskgen.env.CC_NAME not in supported_compilers:
		return

	for flag in ('CFLAGS', 'CXXFLAGS'):
		if taskgen.env.get_flat(flag).find(PREPROCESSOR_FLAG) < 0:
			taskgen.env.append_value(flag, PREPROCESSOR_FLAG)

	# Figure out what casing conventions the user's shell used when
	# launching Waf
	(drive, _) = os.path.splitdrive(taskgen.bld.srcnode.abspath())
	taskgen.msvcdeps_drive_lowercase = drive == drive.lower()

def path_to_node(base_node, path, cached_nodes):
	# Take the base node and the path and return a node
	# Results are cached because searching the node tree is expensive
	# The following code is executed by threads, it is not safe, so a lock is needed...
	if getattr(path, '__hash__'):
		node_lookup_key = (base_node, path)
	else:
		# Not hashable, assume it is a list and join into a string
		node_lookup_key = (base_node, os.path.sep.join(path))
	try:
		lock.acquire()
		node = cached_nodes[node_lookup_key]
	except KeyError:
		node = base_node.find_resource(path)
		cached_nodes[node_lookup_key] = node
	finally:
		lock.release()
	return node

def post_run(self):
	if self.env.CC_NAME not in supported_compilers:
		return super(self.derived_msvcdeps, self).post_run()

	# TODO this is unlikely to work with netcache
	if getattr(self, 'cached', None):
		return Task.Task.post_run(self)

	bld = self.generator.bld
	unresolved_names = []
	resolved_nodes = []

	lowercase = self.generator.msvcdeps_drive_lowercase
	correct_case_path = bld.path.abspath()
	correct_case_path_len = len(correct_case_path)
	correct_case_path_norm = os.path.normcase(correct_case_path)

	# Dynamically bind to the cache
	try:
		cached_nodes = bld.cached_nodes
	except AttributeError:
		cached_nodes = bld.cached_nodes = {}

	for path in self.msvcdeps_paths:
		node = None
		if os.path.isabs(path):
			# Force drive letter to match conventions of main source tree
			drive, tail = os.path.splitdrive(path)

			if os.path.normcase(path[:correct_case_path_len]) == correct_case_path_norm:
				# Path is in the sandbox, force it to be correct.  MSVC sometimes returns a lowercase path.
				path = correct_case_path + path[correct_case_path_len:]
			else:
				# Check the drive letter
				if lowercase and (drive != drive.lower()):
					path = drive.lower() + tail
				elif (not lowercase) and (drive != drive.upper()):
					path = drive.upper() + tail
			node = path_to_node(bld.root, path, cached_nodes)
		else:
			base_node = bld.bldnode
			# when calling find_resource, make sure the path does not begin by '..'
			path = [k for k in Utils.split_path(path) if k and k != '.']
			while path[0] == '..':
				path = path[1:]
				base_node = base_node.parent

			node = path_to_node(base_node, path, cached_nodes)

		if not node:
			raise ValueError('could not find %r for %r' % (path, self))
		else:
			if not c_preproc.go_absolute:
				if not (node.is_child_of(bld.srcnode) or node.is_child_of(bld.bldnode)):
					# System library
					Logs.debug('msvcdeps: Ignoring system include %r', node)
					continue

			if id(node) == id(self.inputs[0]):
				# Self-dependency
				continue

			resolved_nodes.append(node)

	bld.node_deps[self.uid()] = resolved_nodes
	bld.raw_deps[self.uid()] = unresolved_names

	try:
		del self.cache_sig
	except AttributeError:
		pass

	Task.Task.post_run(self)

def scan(self):
	if self.env.CC_NAME not in supported_compilers:
		return super(self.derived_msvcdeps, self).scan()

	resolved_nodes = self.generator.bld.node_deps.get(self.uid(), [])
	unresolved_names = []
	return (resolved_nodes, unresolved_names)

def sig_implicit_deps(self):
	if self.env.CC_NAME not in supported_compilers:
		return super(self.derived_msvcdeps, self).sig_implicit_deps()

	try:
		return Task.Task.sig_implicit_deps(self)
	except Errors.WafError:
		return Utils.SIG_NIL

def exec_command(self, cmd, **kw):
	if self.env.CC_NAME not in supported_compilers:
		return super(self.derived_msvcdeps, self).exec_command(cmd, **kw)

	if not 'cwd' in kw:
		kw['cwd'] = self.get_cwd()

	if self.env.PATH:
		env = kw['env'] = dict(kw.get('env') or self.env.env or os.environ)
		env['PATH'] = self.env.PATH if isinstance(self.env.PATH, str) else os.pathsep.join(self.env.PATH)

	# The Visual Studio IDE adds an environment variable that causes
	# the MS compiler to send its textual output directly to the
	# debugging window rather than normal stdout/stderr.
	#
	# This is unrecoverably bad for this tool because it will cause
	# all the dependency scanning to see an empty stdout stream and
	# assume that the file being compiled uses no headers.
	#
	# See http://blogs.msdn.com/b/freik/archive/2006/04/05/569025.aspx
	#
	# Attempting to repair the situation by deleting the offending
	# envvar at this point in tool execution will not be good enough--
	# its presence poisons the 'waf configure' step earlier. We just
	# want to put a sanity check here in order to help developers
	# quickly diagnose the issue if an otherwise-good Waf tree
	# is then executed inside the MSVS IDE.
	assert 'VS_UNICODE_OUTPUT' not in kw['env']

	cmd, args = self.split_argfile(cmd)
	try:
		(fd, tmp) = tempfile.mkstemp()
		os.write(fd, '\r\n'.join(args).encode())
		os.close(fd)

		self.msvcdeps_paths = []
		kw['env'] = kw.get('env', os.environ.copy())
		kw['cwd'] = kw.get('cwd', os.getcwd())
		kw['quiet'] = Context.STDOUT
		kw['output'] = Context.STDOUT

		out = []
		if Logs.verbose:
			Logs.debug('argfile: @%r -> %r', tmp, args)
		try:
			raw_out = self.generator.bld.cmd_and_log(cmd + ['@' + tmp], **kw)
			ret = 0
		except Errors.WafError as e:
			raw_out = e.stdout
			ret = e.returncode

		for line in raw_out.splitlines():
			if line.startswith(INCLUDE_PATTERN):
				inc_path = line[len(INCLUDE_PATTERN):].strip()
				Logs.debug('msvcdeps: Regex matched %s', inc_path)
				self.msvcdeps_paths.append(inc_path)
			else:
				out.append(line)

		# Pipe through the remaining stdout content (not related to /showIncludes)
		if self.generator.bld.logger:
			self.generator.bld.logger.debug('out: %s' % os.linesep.join(out))
		else:
			sys.stdout.write(os.linesep.join(out) + os.linesep)

		return ret
	finally:
		try:
			os.remove(tmp)
		except OSError:
			# anti-virus and indexers can keep files open -_-
			pass


def wrap_compiled_task(classname):
	derived_class = type(classname, (Task.classes[classname],), {})
	derived_class.derived_msvcdeps = derived_class
	derived_class.post_run = post_run
	derived_class.scan = scan
	derived_class.sig_implicit_deps = sig_implicit_deps
	derived_class.exec_command = exec_command

for k in ('c', 'cxx'):
	if k in Task.classes:
		wrap_compiled_task(k)

def options(opt):
	raise ValueError('Do not load msvcdeps options')

