#!/usr/bin/env bash
set -euo pipefail

cr=$(printf "\r")
status=0

for file in "$@"; do
    IFS= read -r first_line < "$file" || true

    case "$first_line" in
        "#!"*"$cr")
            echo "$file: trailing <CR> in interpreter: $first_line"
            status=1
            continue
            ;;
    esac

    if ! bash -n "$file"; then
        echo "$file: bash -n syntax check failed"
        status=1
    fi

    # Bash 5.1 requires a separator before then after a conditional command.
    if ! awk '
        /\]\][ \t]+then([ \t;]|$)/ || (continued && /^[ \t]*then([ \t;]|$)/) {
            printf "%s:%d: Bash 5.1 requires a newline or semicolon before then\n", FILENAME, NR
            failed = 1
        }
        { continued = /\]\][ \t]*\\$/ }
        END { exit failed }
    ' "$file"; then
        status=1
    fi
done

exit "$status"