"""
Generates documentation based off the available static analyzers checks
References Checkers.td to determine what checks exist
"""

import argparse
import subprocess
import json
import os
import re

"""Get path of script so files are always in correct directory"""
__location__ = os.path.realpath(
        os.path.join(os.getcwd(), os.path.dirname(__file__)))

"""Get dict of checker related info and parse for full check names

Returns:
  checkers: dict of checker info
"""
def get_checkers(checkers_td_directory):
  p = subprocess.Popen(["llvm-tblgen", "--dump-json", "-I",
                           checkers_td_directory, checkers_td_directory+"Checkers.td"],
                           stdout=subprocess.PIPE)
  table_entries = json.loads(p.communicate()[0])
  documentable_checkers = []
  checkers = table_entries["!instanceof"]["Checker"]
  packages = table_entries["!instanceof"]["Package"]

  for checker_ in checkers:
    checker = table_entries[checker_]
    checker_name = checker["CheckerName"]
    package_ = checker["ParentPackage"]["def"]
    package = table_entries[package_]
    package_name = package["PackageName"]
    checker_package_prefix = package_name
    parent_package_ = package["ParentPackage"]
    hidden = (checker["Hidden"] != 0) or (package["Hidden"] != 0)

    while(parent_package_ != None):
      parent_package = table_entries[parent_package_["def"]]
      checker_package_prefix = parent_package["PackageName"] + "." + checker_package_prefix
      hidden = hidden or parent_package["Hidden"] != 0
      parent_package_ = parent_package["ParentPackage"]

    full_package_name = "clang-analyzer-" + checker_package_prefix + "." + checker_name
    anchor_url = re.sub("\.", "-", checker_package_prefix + "." + checker_name).lower()

    if(not hidden and "alpha" not in full_package_name.lower()):
      checker["FullPackageName"] = full_package_name
      checker["AnchorUrl"] = anchor_url
      documentable_checkers.append(checker)

  documentable_checkers.sort(key=lambda x: x["FullPackageName"])
  return documentable_checkers

"""Generate documentation for checker

Args:
  checker: Checker for which to generate documentation.
  only_help_text: Generate documentation based off the checker description.
    Used when there is no other documentation to link to.
"""
def generate_documentation(checker, only_help_text=False):
  with open(os.path.join(__location__, checker["FullPackageName"]+".rst"),"w") as f:
    f.write(".. title:: clang-tidy - %s\n" % checker["FullPackageName"])
    if(not only_help_text):
      f.write(".. meta::\n")
      f.write("   :http-equiv=refresh: 5;URL=https://clang.llvm.org/docs/analyzer/checkers.html#%s\n" % checker["AnchorUrl"])
    f.write("\n")
    f.write("%s\n" % checker["FullPackageName"])
    f.write("=" * len(checker["FullPackageName"]) + "\n")
    f.write("\n")
    if(only_help_text):
      f.write("%s\n" % checker["HelpText"])
    else:
      f.write("The %s check is an alias, please see\n" % checker["FullPackageName"])
      f.write("`Clang Static Analyzer Available Checkers <https://clang.llvm.org/docs/analyzer/checkers.html#%s>`_\n" % checker["AnchorUrl"])
      f.write("for more information.\n")
    f.close()

"""Update list.rst to include the new checks

Args:
  checkers: dict acquired from get_checkers()
"""
def update_documentation_list(checkers):
  with open(os.path.join(__location__, "list.rst"), "r+") as f:
    f_text = f.read()
    header, check_text= f_text.split(".. toctree::\n")
    checks = check_text.split("\n")
    for checker in checkers:
      if(("   %s" % checker["FullPackageName"]) not in checks):
        checks.append("   %s" % checker["FullPackageName"])
    checks.sort()

    #Overwrite file with new data
    f.seek(0)
    f.write(header)
    f.write(".. toctree::")
    for check in checks:
      f.write("%s\n" % check)
    f.close()

default_path_monorepo = '../../../../clang/include/clang/StaticAnalyzer/Checkers/'
default_path_in_tree = '../../../../../include/clang/StaticAnalyzer/Checkers/'

def parse_arguments():
  """Set up and parse command-line arguments
  Returns:
    file_path: Path to Checkers.td"""
  usage = """Parse Checkers.td to generate documentation for static analyzer checks"""
  parse = argparse.ArgumentParser(description=usage)

  file_path_help = ("""Path to Checkers directory
                    defaults to ../../../../clang/include/clang/StaticAnalyzer/Checkers/ if it exists
                    then to ../../../../../include/clang/StaticAnalyzer/Checkers/""")

  default_path=None
  if(os.path.exists(default_path_monorepo)):
    default_path = default_path_monorepo
  elif(os.path.exists(default_path_in_tree)):
    default_path = default_path_in_tree

  parse.add_argument("file", type=str, help=file_path_help, nargs='?', default=default_path)
  args = parse.parse_args()

  if(args.file is None):
    print("Could not find Checkers directory. Please see -h")
    exit(1)

  return args.file


def main():
  file_path = parse_arguments()
  checkers = get_checkers(file_path)
  for checker in checkers:
    #No documentation nor alpha documentation
    if(checker["Documentation"][1] == 0 and checker["Documentation"][0] == 0):
      generate_documentation(checker, True)
    else:
      generate_documentation(checker)
    print("Generated documentation for: %s" % checker["FullPackageName"])
  update_documentation_list(checkers)

if __name__ == '__main__':
  main()