from collections import defaultdict


class ChromosomeAnalyzer:
    def __init__(self, input_file):
        self.input_file = input_file
        self.chromosome_lengths = self.get_chromosome_lengths()

    def get_chromosome_lengths(self):
        # This method should be implemented to return actual chromosome lengths
        return {f"chr{i}": 100000000 for i in range(1, 23)} | {"chrX": 100000000, "chrY": 50000000}

    def analyze(self):
        sv_counts = defaultdict(int)
        with open(self.input_file) as f:
            for line in f:
                if line.startswith("#"):
                    continue
                fields = line.strip().split("\t")
                chrom = fields[0]
                sv_counts[chrom] += 1

        result = "Chromosome Distribution:\n"
        for chrom, count in sv_counts.items():
            density = count / (self.chromosome_lengths.get(chrom, 1) / 1000000)
            result += f"{chrom}: {count} SVs (Density: {density:.2f} SVs/Mb)\n"

        return result
