process SAMTOOLS_VIEW {
    tag "$meta.id"
    label 'process_low'

    conda (params.enable_conda ? "bioconda::samtools=1.16.1" : null)
    container "${ workflow.containerEngine == 'singularity' && !task.ext.singularity_pull_docker_container ?
        'https://depot.galaxyproject.org/singularity/samtools:1.16.1--h6899075_1' :
        'quay.io/biocontainers/samtools:1.16.1--h6899075_1' }"

    input:
    tuple val(meta), path(input), path(index)
    path fasta
    path qname

    output:
    tuple val(meta), path("*.bam"),  emit: bam,     optional: true
    tuple val(meta), path("*.cram"), emit: cram,    optional: true
    tuple val(meta), path("*.sam"),  emit: sam,     optional: true
    tuple val(meta), path("*.bai"),  emit: bai,     optional: true
    tuple val(meta), path("*.csi"),  emit: csi,     optional: true
    tuple val(meta), path("*.crai"), emit: crai,    optional: true
    path  "versions.yml",            emit: versions

    when:
    task.ext.when == null || task.ext.when

    script:
    def args = task.ext.args ?: ''
    def args2 = task.ext.args2 ?: ''
    def prefix = task.ext.prefix ?: "${meta.id}"
    def reference = fasta ? "--reference ${fasta}" : ""
    def readnames = qname ? "--qname-file ${qname}": ""
    def file_type = args.contains("--output-fmt sam") ? "sam" :
                    args.contains("--output-fmt bam") ? "bam" :
                    args.contains("--output-fmt cram") ? "cram" :
                    input.getExtension()
    if ("$input" == "${prefix}.${file_type}") error "Input and output names are the same, use \"task.ext.prefix\" to disambiguate!"
    """
    samtools \\
        view \\
        --threads ${task.cpus-1} \\
        ${reference} \\
        ${readnames} \\
        $args \\
        -o ${prefix}.${file_type} \\
        $input \\
        $args2

    cat <<-END_VERSIONS > versions.yml
    "${task.process}":
        samtools: \$(echo \$(samtools --version 2>&1) | sed 's/^.*samtools //; s/Using.*\$//')
    END_VERSIONS
    """

    stub:
    def prefix = task.ext.prefix ?: "${meta.id}"
    """
    touch ${prefix}.bam
    touch ${prefix}.cram

    cat <<-END_VERSIONS > versions.yml
    "${task.process}":
        samtools: \$(echo \$(samtools --version 2>&1) | sed 's/^.*samtools //; s/Using.*\$//')
    END_VERSIONS
    """
}
