import {
  createPrompt,
  isDownKey,
  isEnterKey,
  isNumberKey,
  isSpaceKey,
  isUpKey,
  makeTheme,
  Separator,
  useKeypress,
  useMemo,
  usePagination,
  usePrefix,
  useRef,
  useState,
  ValidationError,
} from "@inquirer/core";
import figures from "@inquirer/figures";
import ansiEscapes from "ansi-escapes";
import colors from "picocolors";

const checkboxTheme = {
  icon: {
    checked: colors.green(figures.circleFilled),
    unchecked: figures.circle,
    cursor: figures.pointer,
  },
  style: {
    disabledChoice: (text) => colors.dim(`- ${text}`),
    renderSelectedChoices: (selectedChoices) =>
      selectedChoices.map((choice) => choice.short).join(", "),
    description: (text) => colors.cyan(text),
  },
  helpMode: "auto",
};

function isSelectable(item) {
  return !Separator.isSeparator(item) && !item.disabled;
}

function isChecked(item) {
  return isSelectable(item) && Boolean(item.checked);
}

function toggle(item) {
  return isSelectable(item) ? { ...item, checked: !item.checked } : item;
}

function check(checked) {
  return function (item) {
    return isSelectable(item) ? { ...item, checked } : item;
  };
}

function normalizeChoices(choices) {
  return choices.map((choice) => {
    if (Separator.isSeparator(choice)) return choice;

    if (typeof choice === "string") {
      return {
        value: choice,
        name: choice,
        short: choice,
        disabled: false,
        checked: false,
      };
    }

    const name = choice.name ?? String(choice.value);
    return {
      value: choice.value,
      name,
      short: choice.short ?? name,
      description: choice.description,
      disabled: choice.disabled ?? false,
      checked: choice.checked ?? false,
    };
  });
}

export default createPrompt((config, done) => {
  const {
    instructions,
    pageSize = 7,
    loop = true,
    required,
    validate = () => true,
  } = config;
  const theme = makeTheme(checkboxTheme, config.theme);
  const firstRender = useRef(true);
  const [status, setStatus] = useState("idle");
  const prefix = usePrefix({ status, theme });
  const [items, setItems] = useState(
    normalizeChoices(
      typeof config.choices === "function" ? config.choices([]) : config.choices
    )
  );

  const bounds = useMemo(() => {
    const first = items.findIndex(isSelectable);
    const last = items.findLastIndex(isSelectable);

    if (first === -1) {
      throw new ValidationError(
        "[checkbox prompt] No selectable choices. All choices are disabled."
      );
    }

    return { first, last };
  }, [items]);

  const [active, setActive] = useState(bounds.first);
  const [showHelpTip, setShowHelpTip] = useState(true);
  const [errorMsg, setError] = useState();

  useKeypress(async (key) => {
    if (isEnterKey(key)) {
      const selection = items.filter(isChecked);
      const isValid = await validate([...selection]);
      if (required && !items.some(isChecked)) {
        setError("At least one choice must be selected");
      } else if (isValid === true) {
        setStatus("done");
        done(selection.map((choice) => choice.value));
      } else {
        setError(isValid || "You must select a valid value");
      }
    } else if (isUpKey(key) || isDownKey(key)) {
      if (
        loop ||
        (isUpKey(key) && active !== bounds.first) ||
        (isDownKey(key) && active !== bounds.last)
      ) {
        const offset = isUpKey(key) ? -1 : 1;
        let next = active;
        do {
          next = (next + offset + items.length) % items.length;
        } while (!isSelectable(items[next]));
        setActive(next);
      }
    } else if (isSpaceKey(key)) {
      setError(undefined);
      setShowHelpTip(false);
      let newItems = items.map((choice, i) =>
        i === active ? toggle(choice) : choice
      );
      if (typeof config.choices === "function") {
        const selected = newItems
          .filter(isChecked)
          .map((choice) => choice.value);
        const choices = config.choices(selected);
        newItems = newItems.map((choice) => {
          const updated = choices.find((c) => c.value === choice.value);
          return { ...choice, ...updated };
        });
      }
      setItems(newItems);
    } else if (key.name === "a") {
      const selectAll = items.some(
        (choice) => isSelectable(choice) && !choice.checked
      );
      setItems(items.map(check(selectAll)));
    } else if (key.name === "i") {
      setItems(items.map(toggle));
    } else if (isNumberKey(key)) {
      // Adjust index to start at 1
      const position = Number(key.name) - 1;
      const item = items[position];
      if (item != null && isSelectable(item)) {
        setActive(position);
        setItems(
          items.map((choice, i) => (i === position ? toggle(choice) : choice))
        );
      }
    }
  });

  const message = theme.style.message(config.message, status);

  let description;
  const page = usePagination({
    items,
    active,
    renderItem({ item, isActive }) {
      if (Separator.isSeparator(item)) {
        return ` ${item.separator}`;
      }

      if (item.disabled) {
        const disabledLabel =
          typeof item.disabled === "string" ? item.disabled : "(disabled)";
        return theme.style.disabledChoice(`${item.name} ${disabledLabel}`);
      }

      if (isActive) {
        description = item.description;
      }

      const checkbox = item.checked ? theme.icon.checked : theme.icon.unchecked;
      const color = isActive ? theme.style.highlight : (x) => x;

      const cursor = isActive ? theme.icon.cursor : " ";
      return color(`${cursor}${checkbox} ${item.name}`);
    },
    pageSize,
    loop,
  });

  if (status === "done") {
    const selection = items.filter(isChecked);
    const answer = theme.style.answer(
      theme.style.renderSelectedChoices(selection, items)
    );

    return `${prefix} ${message} ${answer}`;
  }

  let helpTipTop = "";
  let helpTipBottom = "";
  if (
    theme.helpMode === "always" ||
    (theme.helpMode === "auto" &&
      showHelpTip &&
      (instructions === undefined || instructions))
  ) {
    if (typeof instructions === "string") {
      helpTipTop = instructions;
    } else {
      const keys = [
        `${theme.style.key("space")} to select`,
        `${theme.style.key("a")} to toggle all`,
        `${theme.style.key("i")} to invert selection`,
        `and ${theme.style.key("enter")} to proceed`,
      ];
      helpTipTop = ` (Press ${keys.join(", ")})`;
    }

    if (
      items.length > pageSize &&
      (theme.helpMode === "always" ||
        (theme.helpMode === "auto" && firstRender.current))
    ) {
      helpTipBottom = `\n${theme.style.help("(Use arrow keys to reveal more choices)")}`;
      firstRender.current = false;
    }
  }

  const choiceDescription = description
    ? `\n${theme.style.description(description)}`
    : ``;

  let error = "";
  if (errorMsg) {
    error = `\n${theme.style.error(errorMsg)}`;
  }

  return `${prefix} ${message}${helpTipTop}\n${page}${helpTipBottom}${choiceDescription}${error}${ansiEscapes.cursorHide}`;
});

export { Separator } from "@inquirer/core";