#!/usr/bin/env python
# -*- coding: utf-8 -*-

import os
import re
import sys

EMPTY_MATCHER = re.compile(r'^\s*$')
C_COMMENT_MATCHER = re.compile(r'^/\*.*\*/', re.S)

IFDEF_MATCHER = re.compile(r'#\s*if')
ENDDEF_MATCHER = re.compile(r'#\s*endif')

USER_INCLUDE_MATCHER = re.compile(r'#\s*include\s*\"(.*)\"')
SYSTEM_INCLUDE_MATCHER = re.compile(r'#\s*include\s*<(.*)>')
PRAGMA_ONCE_MATCHER = re.compile(r'#\s*pragma\s+once')


def CollectLicenseComment(headerPath):
    with open(headerPath, "r") as headerStream:
        headerContent = headerStream.read().strip()
        commentMatch = re.match(C_COMMENT_MATCHER, headerContent)
        return commentMatch.group() if commentMatch else ""


def CollectSystemIncludes(headerPath, parsedHeaders=set()):
    with open(headerPath, "r") as headerStream:
        headerContent = headerStream.read().strip()

        if PRAGMA_ONCE_MATCHER.search(headerContent) and headerPath in parsedHeaders:
            return set()

        ifdefScopeLevel = 0
        headerIncludes = set()

        parsedHeaders.add(headerPath)
        headerLines = headerContent.split('\n')

        for headerLine in headerLines:
            if IFDEF_MATCHER.match(headerLine):
                ifdefScopeLevel += 1
            elif ENDDEF_MATCHER.match(headerLine):
                ifdefScopeLevel -= 1

            includeMatch = USER_INCLUDE_MATCHER.findall(headerLine)
            if includeMatch and ifdefScopeLevel == 0:
                internalHeaderPath = os.path.abspath(os.path.join(
                    os.path.dirname(headerPath), includeMatch[0]))
                headerIncludes = headerIncludes.union(
                    CollectSystemIncludes(internalHeaderPath, parsedHeaders))

            includeMatch = SYSTEM_INCLUDE_MATCHER.findall(headerLine)
            if includeMatch and ifdefScopeLevel == 0:
                headerIncludes.add(includeMatch[0])

        return headerIncludes


def ParseHeader(headerPath, parsedHeaders=set()):
    with open(headerPath, "r") as headerStream:
        headerContent = headerStream.read().strip()
        headerContent = re.sub(C_COMMENT_MATCHER, '', headerContent)

        if PRAGMA_ONCE_MATCHER.search(headerContent) and headerPath in parsedHeaders:
            return ""

        parsedHeaders.add(headerPath)
        headerLines = headerContent.split('\n')

        outputContent = ""
        ifdefScopeLevel = 0
        shouldSkipNextEmptyLines = True

        for headerLine in headerLines:
            if EMPTY_MATCHER.match(headerLine) and shouldSkipNextEmptyLines:
                continue

            if PRAGMA_ONCE_MATCHER.match(headerLine):
                shouldSkipNextEmptyLines = True
                continue

            if IFDEF_MATCHER.match(headerLine):
                ifdefScopeLevel += 1
            elif ENDDEF_MATCHER.match(headerLine):
                ifdefScopeLevel -= 1

            includeMatch = USER_INCLUDE_MATCHER.findall(headerLine)
            if includeMatch and ifdefScopeLevel == 0:
                internalHeaderPath = os.path.abspath(os.path.join(
                    os.path.dirname(headerPath), includeMatch[0]))
                internalHeaderContent = ParseHeader(
                    internalHeaderPath, parsedHeaders)

                outputContent += internalHeaderContent
                shouldSkipNextEmptyLines = True
                continue

            includeMatch = SYSTEM_INCLUDE_MATCHER.findall(headerLine)
            if includeMatch and ifdefScopeLevel == 0:
                shouldSkipNextEmptyLines = True
                continue

            shouldSkipNextEmptyLines = False
            outputContent += "{}\n".format(headerLine)

        return "{}\n".format(outputContent)


inputHeaderPath = os.path.abspath(sys.argv[1])
outputHeaderPath = os.path.abspath(sys.argv[2])

os.makedirs(os.path.dirname(outputHeaderPath), exist_ok=True)

with open(outputHeaderPath, "w") as outputHeaderStream:
    licenseComment = CollectLicenseComment(inputHeaderPath)
    systemIncludes = CollectSystemIncludes(inputHeaderPath)
    headersContent = ParseHeader(inputHeaderPath)

    if licenseComment:
        outputHeaderStream.write("{}\n".format(licenseComment))
        outputHeaderStream.write("\n")

    outputHeaderStream.write("#pragma once\n")
    outputHeaderStream.write("\n")

    if systemIncludes:
        for systemInclude in sorted(systemIncludes):
            outputHeaderStream.write("#include <{}>\n".format(systemInclude))
        outputHeaderStream.write("\n")

    if headersContent:
        outputHeaderStream.write(headersContent.strip())
        outputHeaderStream.write("\n")