#!/usr/bin/python3

import os
import hashlib
from subprocess import run

build_files_src = {}
build_files_level = {}
build_files_toBuild = {}

def check_if_file(filename, build_file_name):
    """ Checks it the given file exists, else print error and exit """
    if os.path.isfile(filename):
        return True
    else:
        print("In " + build_file_name + " : " +  filename + " is not a file")
        exit(1)

def getmd5(filename):
    """ Takes Path to a file and get it's md5sum """
    with open(filename, 'rb') as file_to_check:
        data = file_to_check.read()
        md5_returned = hashlib.md5(data).hexdigest()
    return md5_returned

def get_meta_file(filename):
    """ Takes src file name in build file and converts it to entry in .flow folder filename """
    fname = ""
    for letter in filename:
        if letter == "." or letter == "\\" or letter == "/":
            pass
        else:
            fname += letter
    return fname

def update_md5(filename):
    """ Takes the filename in .flow as var fname and updates it's md5sum value according to contents of var filename """
    fname = get_meta_file(filename)
    with open(".flow/" + fname, "w") as f:
        f.write(getmd5(filename).strip())


def getstoredmd5(filename):
    """ get value of file's md5 from .flow folder, else create entry. return the (md5, createdEntry)"""
    md5_returned = ""
    fname = get_meta_file(filename)
    if fname in os.listdir(".flow"):
        with open(".flow/" + fname, "r") as f:
            md5_returned = f.readline()
    else:
        print("INFO : md5sum entry not present for " + filename + " creating one.")
        update_md5(filename)
    return md5_returned

def recieved_file(filename, level, rebuild):
    if build_files_toBuild.get(filename, False) == False:
        build_files_toBuild[filename] = rebuild
    if build_files_level.get(filename, -1) < level:
        build_files_level[filename] = level
        pass
    
    start, mid, end = "", "", ""
    with open(filename, "r") as f:
        x = f.read().split(";!run!;")
        start = x[0]
        y = x[1].split(";!end!;")
        mid = y[0]
        end = y[1]

    # start
    src_files = []
    for line in start.split():
        entry = line.strip()
        src_files.append(entry)

    build_files_src[filename] = src_files
    
    if rebuild:
        build_files_toBuild[filename] = True
    else:
        for line in start.split():
            entry = line.strip()
            check_if_file(entry, filename)
            new_md5, old_md5 = "", ""
            new_md5 = getmd5(entry)
            old_md5 = getstoredmd5(entry)
            
            if old_md5 != new_md5:
                print(entry + " was modified")
                build_files_toBuild[filename] = True

    # mid
    if build_files_toBuild[filename]:
        with open(filename + ".temp", "w") as f:
            f.write(mid)

    # end
    for line in end.split():
        entry = line.strip()
        check_if_file(entry, filename)
        recieved_file(entry, level + 1, build_files_toBuild[filename])
        
    

def main():
    with open("build.flow", "r") as main_build_file:
        if not os.path.exists(".flow"):
            os.makedirs(".flow")
        for line in main_build_file:
            entry = line.strip()
            
            if os.path.isfile(entry):
                recieved_file(entry, 0, False)
            else:
                print("ERROR : " + entry + " is neither a file or a directory")
                exit(1)

    print(build_files_level)
    print(build_files_src)
    print(build_files_toBuild)
    print()
    print("┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ┅ ")
    print()

    """ Build by using the data structures """
    for f, x  in list(build_files_toBuild.items()):
        if x == False:
            del build_files_level[f]
            del build_files_src[f]
            del build_files_toBuild[f]

    levels_list = []
    for f,x in build_files_level.items():
        levels_list.append((f,x))

    n = len(levels_list)
    for i in range(n):
        for j in range(0, n-i-1):
            if levels_list[j][1] > levels_list[j+1][1]:
                levels_list[j], levels_list[j+1] = levels_list[j+1], levels_list[j]

    for item in levels_list:
        p = run([ "bash", item[0] + ".temp"  ])
        if p.returncode != 0:
            print(p)
            exit(p.returncode)

    for item in levels_list:
        build_file_name = item[0]
        for src_file in build_files_src[build_file_name]:
            update_md5(src_file)
        
main()