Multiple Selector

'use client';

import * as React from 'react';
import { X } from 'lucide-react';

import {
  Command,
  CommandGroup,
  CommandItem,
  CommandEmpty,
  CommandList,
} from '@/components/ui/command';
import { Command as CommandPrimitive } from 'cmdk';
import { useEffect } from 'react';
import { Badge } from '@/components/ui/badge';
import { cn } from '@/lib/utils';

export interface Option {
  value: string;
  label: string;
  disable?: boolean;
  /** fixed option that can't be removed. */
  fixed?: boolean;
  /** Group the options by providing key. */
  [key: string]: string | boolean | undefined;
}
interface GroupOption {
  [key: string]: Option[];
}

interface MultipleSelectorProps {
  value?: Option[];
  options?: Option[];
  placeholder?: string;
  /** Loading component. */
  loadingIndicator?: React.ReactNode;
  /** Empty component. */
  emptyIndicator?: React.ReactNode;
  /** Debounce time for async search. Only work with `onSearch`. */
  delay?: number;
  /** async search */
  onSearch?: (value: string) => Promise<Option[]>;
  onChange?: (options: Option[]) => void;
  /** Limit the maximum number of selected options. */
  maxSelected?: number;
  /** When the number of selected options exceeds the limit, the onMaxSelected will be called. */
  onMaxSelected?: (maxLimit: number) => void;
  /** Hide the placeholder when there are options selected. */
  hidePlaceholderWhenSelected?: boolean;
  disabled?: boolean;
  /** Group the options base on provided key. */
  groupBy?: string;
  className?: string;
  badgeClassName?: string;
  /**
   * First item selected is a default behavior by cmdk. That is why the default is true.
   * This is a workaround solution by add a dummy item.
   *
   * @reference: https://github.com/pacocoursey/cmdk/issues/171
   */
  selectFirstItem?: boolean;
  /** Allow user to create option when there is no option matched. */
  creatable?: boolean;
  /** Limit the input text length. */
  maxTextLength?: number;
}

export interface MultipleSelectorRef {
  selectedValue: Option[];
  input: HTMLInputElement;
}

export function useDebounce<T>(value: T, delay?: number): T {
  const [debouncedValue, setDebouncedValue] = React.useState<T>(value);

  useEffect(() => {
    const timer = setTimeout(() => setDebouncedValue(value), delay || 500);

    return () => {
      clearTimeout(timer);
    };
  }, [value, delay]);

  return debouncedValue;
}

function transToGroupOption(options: Option[], groupBy?: string) {
  if (options.length === 0) {
    return {};
  }
  if (!groupBy) {
    return {
      '': options,
    };
  }

  const groupOption: GroupOption = {};
  options.forEach((option) => {
    const key = (option[groupBy] as string) || '';
    if (!groupOption[key]) {
      groupOption[key] = [];
    }
    groupOption[key].push(option);
  });
  return groupOption;
}

function removePickedOption(groupOption: GroupOption, picked: Option[]) {
  const cloneOption = JSON.parse(JSON.stringify(groupOption)) as GroupOption;

  for (const [key, value] of Object.entries(cloneOption)) {
    cloneOption[key] = value.filter((val) => !picked.find((p) => p.value === val.value));
  }
  return cloneOption;
}

const MultipleSelector = React.forwardRef<MultipleSelectorRef, MultipleSelectorProps>(
  (
    {
      value,
      onChange,
      placeholder,
      options: arrayOptions = [],
      delay,
      onSearch,
      loadingIndicator,
      emptyIndicator,
      maxSelected = Number.MAX_SAFE_INTEGER,
      onMaxSelected,
      hidePlaceholderWhenSelected,
      disabled,
      groupBy,
      className,
      badgeClassName,
      selectFirstItem = true,
      creatable = false,
      maxTextLength = Number.MAX_SAFE_INTEGER,
    }: MultipleSelectorProps,
    ref: React.Ref<MultipleSelectorRef>,
  ) => {
    const inputRef = React.useRef<HTMLInputElement>(null);
    const [open, setOpen] = React.useState(false);
    const [isLoading, setIsLoading] = React.useState(false);

    const [selected, setSelected] = React.useState<Option[]>(value || []);
    const [options, setOptions] = React.useState<GroupOption>(
      transToGroupOption(arrayOptions, groupBy),
    );

    const [inputValue, setInputValue] = React.useState('');
    const debouncedSearchTerm = useDebounce(inputValue, delay || 500);

    React.useImperativeHandle(
      ref,
      () => ({
        selectedValue: [...selected],
        input: inputRef.current as HTMLInputElement,
      }),
      [selected],
    );

    const handleUnselect = React.useCallback(
      (option: Option) => {
        const newOptions = selected.filter((s) => s.value !== option.value);
        setSelected(newOptions);
        onChange?.(newOptions);
      },
      [selected],
    );

    const handleKeyDown = React.useCallback(
      (e: React.KeyboardEvent<HTMLDivElement>) => {
        const input = inputRef.current;
        if (input) {
          if (e.key === 'Delete' || e.key === 'Backspace') {
            if (input.value === '' && selected.length > 0) {
              handleUnselect(selected[selected.length - 1]);
            }
          }
          // This is not a default behaviour of the <input /> field
          if (e.key === 'Escape') {
            input.blur();
          }
        }
      },
      [selected],
    );

    useEffect(() => {
      if (value) {
        setSelected(value);
      }
    }, [value]);

    useEffect(() => {
      const exec = async () => {
        if (!debouncedSearchTerm || !onSearch) return;
        setIsLoading(true);
        const res = await onSearch?.(debouncedSearchTerm);
        setOptions(transToGroupOption(res, groupBy));
        setIsLoading(false);
      };

      void exec();
    }, [debouncedSearchTerm]);

    const CreatableItem = () => {
      if (!creatable) return undefined;

      const Item = (
        <CommandItem
          value={inputValue}
          className="cursor-pointer"
          onMouseDown={(e) => {
            e.preventDefault();
            e.stopPropagation();
          }}
          onSelect={(value: string) => {
            if (selected.length >= maxSelected) {
              onMaxSelected?.(selected.length);
              return;
            }
            setInputValue('');
            const newOptions = [...selected, { value, label: value }];
            setSelected(newOptions);
            onChange?.(newOptions);
          }}
        >{`Create "${inputValue}"`}</CommandItem>
      );

      // for normal creatable
      if (!onSearch && inputValue.length > 0) {
        return Item;
      }

      // for async search creatable. avoid showing creatable item before loading at first.
      if (onSearch && debouncedSearchTerm.length > 0 && !isLoading) {
        return Item;
      }

      return undefined;
    };

    const EmptyItem = () => {
      if (!emptyIndicator) return undefined;

      // for async search that showing emptyIndicator
      if (onSearch && !creatable && Object.keys(options).length === 0) {
        return (
          <CommandItem value="-" disabled>
            {emptyIndicator}
          </CommandItem>
        );
      }

      return <CommandEmpty>{emptyIndicator}</CommandEmpty>;
    };

    const selectables = React.useMemo<GroupOption>(
      () => removePickedOption(options, selected),
      [options, selected],
    );

    return (
      <Command
        onKeyDown={handleKeyDown}
        className="overflow-visible bg-transparent"
        shouldFilter={!onSearch} // when onSearch is provided, we don't want to filter the options.
      >
        <div
          className={cn(
            'group rounded-md border border-input px-3 py-2 text-sm ring-offset-background focus-within:ring-2 focus-within:ring-ring focus-within:ring-offset-2',
            className,
          )}
        >
          <div className="flex flex-wrap gap-1">
            {selected.map((option) => {
              return (
                <Badge
                  key={option.value}
                  className={cn(
                    'data-[disabled]:bg-muted-foreground data-[disabled]:text-muted data-[disabled]:hover:bg-muted-foreground',
                    'data-[fixed]:bg-muted-foreground data-[fixed]:text-muted data-[fixed]:hover:bg-muted-foreground',
                    badgeClassName,
                  )}
                  data-fixed={option.fixed}
                  data-disabled={disabled}
                >
                  {option.label}
                  <button
                    className={cn(
                      'ml-1 rounded-full outline-none ring-offset-background focus:ring-2 focus:ring-ring focus:ring-offset-2',
                      (disabled || option.fixed) && 'hidden',
                    )}
                    onKeyDown={(e) => {
                      if (e.key === 'Enter') {
                        handleUnselect(option);
                      }
                    }}
                    onMouseDown={(e) => {
                      e.preventDefault();
                      e.stopPropagation();
                    }}
                    onClick={() => handleUnselect(option)}
                  >
                    <X className="h-3 w-3 text-muted-foreground hover:text-foreground" />
                  </button>
                </Badge>
              );
            })}
            {/* Avoid having the "Search" Icon */}
            <CommandPrimitive.Input
              ref={inputRef}
              value={inputValue}
              disabled={disabled}
              onValueChange={setInputValue}
              onBlur={() => setOpen(false)}
              onFocus={() => setOpen(true)}
              placeholder={hidePlaceholderWhenSelected && selected.length !== 0 ? '' : placeholder}
              className="ml-2 flex-1 bg-transparent outline-none placeholder:text-muted-foreground"
              maxLength={maxTextLength}
            />
          </div>
        </div>
        <div className="relative mt-2">
          {open && (
            <CommandList className="absolute top-0 z-10 w-full rounded-md border bg-popover text-popover-foreground shadow-md outline-none animate-in">
              {isLoading ? (
                <>{loadingIndicator}</>
              ) : (
                <>
                  {EmptyItem()}
                  {CreatableItem()}
                  {!selectFirstItem && <CommandItem value="-" className="hidden" />}
                  {Object.entries(selectables).map(([key, dropdowns]) => (
                    <CommandGroup key={key} heading={key} className="h-full overflow-auto">
                      <>
                        {dropdowns.map((option) => {
                          return (
                            <CommandItem
                              key={option.value}
                              value={option.value}
                              disabled={option.disable}
                              onMouseDown={(e) => {
                                e.preventDefault();
                                e.stopPropagation();
                              }}
                              onSelect={() => {
                                if (selected.length >= maxSelected) {
                                  onMaxSelected?.(selected.length);
                                  return;
                                }
                                setInputValue('');
                                const newOptions = [...selected, option];
                                setSelected(newOptions);
                                onChange?.(newOptions);
                              }}
                              className={cn(
                                'cursor-pointer',
                                option.disable && 'cursor-default text-muted-foreground',
                              )}
                            >
                              {option.label}
                            </CommandItem>
                          );
                        })}
                      </>
                    </CommandGroup>
                  ))}
                </>
              )}
            </CommandList>
          )}
        </div>
      </Command>
    );
  },
);

MultipleSelector.displayName = 'MultipleSelector';
export default MultipleSelector;