#!/usr/bin/env python

# encoding: utf-8

# Christoph Koke, 2013

"""

Writes the c and cpp compile commands into build/compile_commands.json

see http://clang.llvm.org/docs/JSONCompilationDatabase.html

Usage:

    def configure(conf):

        conf.load('compiler_cxx')

        ...

        conf.load('clang_compilation_database')

"""

import sys, os, json, shlex, pipes

from waflib import Logs, TaskGen

from waflib.Tools import c, cxx

if sys.hexversion >= 0x3030000:

	quote = shlex.quote

else:

	quote = pipes.quote

@TaskGen.feature('*')

@TaskGen.after_method('process_use')

def collect_compilation_db_tasks(self):

	"Add a compilation database entry for compiled tasks"

	try:

		clang_db = self.bld.clang_compilation_database_tasks

	except AttributeError:

		clang_db = self.bld.clang_compilation_database_tasks = []

		self.bld.add_post_fun(write_compilation_database)

	for task in getattr(self, 'compiled_tasks', []):

		if isinstance(task, (c.c, cxx.cxx)):

			clang_db.append(task)

def write_compilation_database(ctx):

	"Write the clang compilation database as JSON"

	database_file = ctx.bldnode.make_node('compile_commands.json')

	Logs.info("Build commands will be stored in %s" % database_file.path_from(ctx.path))

	try:

		root = json.load(database_file)

	except IOError:

		root = []

	clang_db = dict((x["file"], x) for x in root)

	for task in getattr(ctx, 'clang_compilation_database_tasks', []):

		try:

			cmd = task.last_cmd

		except AttributeError:

			continue

		directory = getattr(task, 'cwd', ctx.variant_dir)

		f_node = task.inputs[0]

		filename = os.path.relpath(f_node.abspath(), directory)

		cmd = " ".join(map(quote, cmd))

		entry = {

			"directory": directory,

			"command": cmd,

			"file": filename,

		}

		clang_db[filename] = entry

	root = list(clang_db.values())

	database_file.write(json.dumps(root, indent=2))