#! /usr/bin/env python3

# pdeps
#
# Find dependencies between a bunch of Python modules.
#
# Usage:
# pdeps file1.py file2.py ...
#
# Output:
# Four tables separated by lines like '--- Closure ---':
# 1) Direct dependencies, listing which module imports which other modules
# 2) The inverse of (1)
# 3) Indirect dependencies, or the closure of the above
# 4) The inverse of (3)
#
# To do:
# - command line options to select output type
# - option to automatically scan the Python library for referenced modules
# - option to limit output to particular modules


import sys
import re
import os


# Main program
#
def main():
 args = sys.argv[1:]
 if not args:
 print('usage: pdeps file.py file.py ...')
 return 2
 #
 table = {}
 for arg in args:
 process(arg, table)
 #
 print('--- Uses ---')
 printresults(table)
 #
 print('--- Used By ---')
 inv = inverse(table)
 printresults(inv)
 #
 print('--- Closure of Uses ---')
 reach = closure(table)
 printresults(reach)
 #
 print('--- Closure of Used By ---')
 invreach = inverse(reach)
 printresults(invreach)
 #
 return 0


# Compiled regular expressions to search for import statements
#
m_import = re.compile('^[ \t]*from[ \t]+([^ \t]+)[ \t]+')
m_from = re.compile('^[ \t]*import[ \t]+([^#]+)')


# Collect data from one file
#
def process(filename, table):
 fp = open(filename, 'r')
 mod = os.path.basename(filename)
 if mod[-3:] == '.py':
 mod = mod[:-3]
 table[mod] = list = []
 while 1:
 line = fp.readline()
 if not line: break
 while line[-1:] == '\\':
 nextline = fp.readline()
 if not nextline: break
 line = line[:-1] + nextline
 m_found = m_import.match(line) or m_from.match(line)
 if m_found:
 (a, b), (a1, b1) = m_found.regs[:2]
 else: continue
 words = line[a1:b1].split(',')
 # print '#', line, words
 for word in words:
 word = word.strip()
 if word not in list:
 list.append(word)
 fp.close()


# Compute closure (this is in fact totally general)
#
def closure(table):
 modules = list(table.keys())
 #
 # Initialize reach with a copy of table
 #
 reach = {}
 for mod in modules:
 reach[mod] = table[mod][:]
 #
 # Iterate until no more change
 #
 change = 1
 while change:
 change = 0
 for mod in modules:
 for mo in reach[mod]:
 if mo in modules:
 for m in reach[mo]:
 if m not in reach[mod]:
 reach[mod].append(m)
 change = 1
 #
 return reach


# Invert a table (this is again totally general).
# All keys of the original table are made keys of the inverse,
# so there may be empty lists in the inverse.
#
def inverse(table):
 inv = {}
 for key in table.keys():
 if key not in inv:
 inv[key] = []
 for item in table[key]:
 store(inv, item, key)
 return inv


# Store "item" in "dict" under "key".
# The dictionary maps keys to lists of items.
# If there is no list for the key yet, it is created.
#
def store(dict, key, item):
 if key in dict:
 dict[key].append(item)
 else:
 dict[key] = [item]


# Tabulate results neatly
#
def printresults(table):
 modules = sorted(table.keys())
 maxlen = 0
 for mod in modules: maxlen = max(maxlen, len(mod))
 for mod in modules:
 list = sorted(table[mod])
 print(mod.ljust(maxlen), ':', end=' ')
 if mod in list:
 print('(*)', end=' ')
 for ref in list:
 print(ref, end=' ')
 print()


# Call main and honor exit status
if __name__ == '__main__':
 try:
 sys.exit(main())
 except KeyboardInterrupt:
 sys.exit(1)