_tasker_task_dirs() {
    local root d name
    if [[ -d "$PWD/tasks" ]]; then
        root="$PWD/tasks"
    else
        root="$PWD"
    fi

    shopt -s nullglob
    for d in "$root"/*/; do
        name="${d%/}"
        name="${name##*/}"
        if [[ "$name" =~ ^[0-9]{2}-[0-9]{2}-[0-9]{2}\ [0-9]{2}:[0-9]{2}:[0-9]{2}(\.[0-9]+)?$ ]]; then
            printf '%s\n' "$name"
        fi
    done
}

_tasker_completion() {
    local cur prev words cword subcommand
    COMPREPLY=()

    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"

    local commands="new list set delete"

    subcommand=""
    for word in "${COMP_WORDS[@]:1}"; do
        case "$word" in
            new|list|set|delete)
                subcommand="$word"
                break
                ;;
        esac
    done

    if [[ -z "$subcommand" ]]; then
        COMPREPLY=( $(compgen -W "$commands" -- "$cur") )
        return 0
    fi

    case "$subcommand" in
        new)
            case "$prev" in
                -p|-d)
                    return 0
                    ;;
            esac
            COMPREPLY=( $(compgen -W "-p -d" -- "$cur") )
            ;;

        list)
            case "$prev" in
                -s|--status)
                    COMPREPLY=( $(compgen -W "OPEN IN_PROGRESS CLOSED" -- "$cur") )
                    return 0
                    ;;
                -p|--priority|--min-priority|-c|--contains)
                    return 0
                    ;;
            esac
            COMPREPLY=( $(compgen -W "-s --status -p --priority --min-priority -c --contains" -- "$cur") )
            ;;

        set)
            case "$prev" in
                -s|--status)
                    COMPREPLY=( $(compgen -W "OPEN IN_PROGRESS CLOSED" -- "$cur") )
                    return 0
                    ;;
                -n|--name|-p|--priority|-d|--desc)
                    return 0
                    ;;
            esac

            if [[ "$cur" == -* ]]; then
                COMPREPLY=( $(compgen -W "-n --name -s --status -p --priority -d --desc" -- "$cur") )
            else
                COMPREPLY=( $(compgen -W "$(_tasker_task_dirs)" -- "$cur") )
            fi
            ;;

        delete)
            COMPREPLY=( $(compgen -W "$(_tasker_task_dirs)" -- "$cur") )
            ;;
    esac
}

complete -F _tasker_completion tasker