from itertools import zip_longest


def grouper(n, iterable, fillvalue=None):
    "grouper(3, 'ABCDEFG', 'x') --> ABC DEF Gxx"
    args = [iter(iterable)] * n
    return zip_longest(fillvalue=fillvalue, *args)


def part1(sections):
    # consume seed section
    _, seeds = next(sections)
    seeds = [int(s) for s in seeds]
    print(seeds)

    for name, numbers in sections:
        # item: range_start, len, offset
        #mapping = []
        #for dst, src, length in grouper(3, numbers):
            #mapping.append((src, lenght, dst))
            #src = range(int(src), int(src) + int(length))
            #dst = range(int(dst), int(dst) + int(length))
            #for k, v in zip(src, dst):
            #    mapping[k] = v
        
        # apply current mapping on input (using linear search)
        new_seeds = []
        for seed in seeds:
            for dst, src, length in grouper(3, numbers):
                src, length, dst = int(src), int(length), int(dst)
                end = dst + (length - 1)
                if src <= seed < end:
                    new_seed = seed + (dst-src)
                    new_seeds.append(new_seed)
                    break
            else:
                new_seeds.append(seed)
        seeds = new_seeds

        print(seeds)
                    

            
        #seeds = [mapping.get(s, None) or s for s in seeds]

    print(f"Part 1, lowest location number = {min(seeds)}")

def parse_input(infile):
    with open(infile) as f:
        sections = f.read().split("\n\n")
        sections = ((title, numbers) for title, numbers in (s.split(":") for s in sections))
        sections = ((title, numbers.split()) for title, numbers in sections)
        return sections


if __name__ == "__main__":
    import sys
    import os
    SCRIPTPATH = os.path.dirname(os.path.realpath(__file__))

    infile = next(iter(sys.argv[1:]), None)
    sections = parse_input(infile or os.path.join(SCRIPTPATH, "example.txt"))
    part1(sections)