#!python
## Copyright (c) 2020-2021 Thakee Nathees
## Distributed Under The MIT License

## This will run a static checks on the source files, for line length,
## uses of tabs and trailing white spaces, etc.
##
## Run the file at the top level of the repository "python3 tests/check.py".

import os, sys, re
from os.path import join
from os import listdir

## A list of source files, to check if the fnv1a hash values match it's
## corresponding cstring in the CASE_ATTRIB(name, hash) macro calls.
HASH_CHECK_LIST = [
  "src/pk_core.c",
]

## A list of directory, contains C source files to perform static checks.
## This will include both '.c' and '.h' files.
C_SOURCE_DIRS = [
  "src/",
  "cli/",
  "cli/modules/",
]

## This global variable will be set to true if any check failed.
checks_failed = False

def main():
  dir = os.path.dirname(os.path.realpath(__file__))
  if dir == os.getcwd():
    print("Run the file from the top level of the repository", file=sys.stderr)
    sys.exit(1)
    
  check_fnv1_hash(HASH_CHECK_LIST)
  check_static(C_SOURCE_DIRS)
  if checks_failed:
    sys.exit(1)
  print("Static checks were passed.")

def check_fnv1_hash(sources):
  PATTERN = r'CASE_ATTRIB\(\s*"([A-Za-z0-9_]+)"\s*,\s*(0x[0-9abcdef]+)\)'
  for file in sources:
    fp = open(file, 'r')
    
    line_no = 0
    for line in fp.readlines():
      line_no += 1
      match = re.findall(PATTERN, line)
      if len(match) == 0: continue
      name, val = match[0]
      hash = hex(fnv1a_hash(name))
      
      if val == hash: continue
      report_error(f"{location(file, line_no)} - hash mismatch. "
        f"hash('{name}') = {hash} not {val}")
        
    fp.close()

## Check each source file ('.c', '.h', '.py') in the [dirs] contains tabs,
## more than 79 characters and trailing white space.
def check_static(dirs):
  valid_ext = ('.c', '.h', '.py', '.pk')
  for dir in dirs:
    
    for file in listdir(dir):
      if not file.endswith(valid_ext): continue
      if os.path.isdir(join(dir, file)): continue
      
      fp = open(join(dir, file), 'r')
      
      ## This will be set to true if the last line is empty.
      is_last_empty = False; line_no = 0
      for line in fp.readlines():
        line_no += 1; line = line[:-1] # remove the line ending.
        
        _location = location(join(dir, file), line_no)
        
        ## Check if the line contains any tabs.
        if '\t' in line:
          report_error(f"{_location} - contains tab(s) ({repr(line)}).")
            
        if len(line) >= 80:
          if 'http://' in line or 'https://' in line: continue
          report_error(
            f"{_location} - contains {len(line)} (> 79) characters.")
            
        if line.endswith(' '):
          report_error(f"{_location} - contains trailing white space.")
            
        if line == '':
          if is_last_empty:
            report_error(f"{_location} - consequent empty lines.")
          is_last_empty = True
        else:
          is_last_empty = False
        
      fp.close()
      

## Returns a formated string of the error location.
def location(file, line):
  return f"{'%-17s'%file} : {'%4s'%line}"

## FNV-1a hash. See: http://www.isthe.com/chongo/tech/comp/fnv/
def fnv1a_hash(string):
  FNV_prime_32_bit = 16777619
  FNV_offset_basis_32_bit = 2166136261
  
  hash = FNV_offset_basis_32_bit
  
  for c in string:
    hash ^= ord(c)
    hash *= FNV_prime_32_bit
    hash &= 0xffffffff ## intentional 32 bit overflow.
  return hash

def report_error(msg):
  global checks_failed
  checks_failed = True
  print(msg, file=sys.stderr)

if __name__ == '__main__':
  main()