import sys

#GC_content: Loop through the sequence array, calculate the gc values, output the values
def GC_content(fasta_file):
    #Loop through the file and create a sequence array
    sequences = {}
    with open(fasta_file, "r") as file:
        name = ""
        for line in file:
            line = line.strip()
            if line.startswith(">"):
                name_sub1 = line[1:]
                name_sub2 = name_sub1.split(" ")
                name = name_sub2[0]
                sequences[name] = ""
            else:
                sequences[name] += line

    #Calculate the gc values, output the values
    print("Gene stable ID" + "\t" + "Transcript stable ID" + "\t" + "Gene % GC content" + "\t" + "GC_ratio" + "\t" + "AT_ratio")
    for transcript, sequence in sequences.items():
        gc_count = sequence.count("G") + sequence.count("C")
        at_count = sequence.count("A") + sequence.count("T")
        gc_ratio = gc_count / at_count
        at_ratio = at_count / gc_count
        gc_content = (100 * gc_count) / (gc_count + at_count)
        gc_content_str = "{:.2f}".format(gc_content)

        parsed_string = transcript.split("_")
        gene_model = parsed_string[0]
        print(gene_model + "\t" + transcript + "\t" + gc_content_str + "\t" + str(gc_ratio) + "\t" + str(at_ratio))

#Call the GC_content function
GC_content(sys.argv[1])