#!/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.
'''

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)