import { ESLintUtils, TSESTree } from "@typescript-eslint/utils";

const createRule = ESLintUtils.RuleCreator(() => `https://docs.twenty.com`);

const checkIsPascalCase = (input: string): boolean => {
  const pascalCaseRegex = /^[A-Z][a-zA-Z0-9_]*/g;

  return pascalCaseRegex.test(input);
};

type ComponentType =
  | TSESTree.FunctionDeclaration
  | TSESTree.ArrowFunctionExpression
  | TSESTree.FunctionExpression;

const effectComponentsRule = createRule({
  create: (context) => {
    const checkThatNodeIsEffectComponent = (node: ComponentType) => {
      let componentName = "";
      let identifierNode = node.id;

      const isIdentifier = (
        node: TSESTree.Node | null,
      ): node is TSESTree.Identifier =>
        node?.type === TSESTree.AST_NODE_TYPES.Identifier;
      const isVariableDeclarator = (
        node: TSESTree.Node,
      ): node is TSESTree.VariableDeclarator =>
        node.type === TSESTree.AST_NODE_TYPES.VariableDeclarator;

      const isArrowFunction = (
        node: TSESTree.Node,
      ): node is TSESTree.ArrowFunctionExpression =>
        node.type === TSESTree.AST_NODE_TYPES.ArrowFunctionExpression;
      const isFunctionDeclaration = (
        node: TSESTree.Node,
      ): node is TSESTree.FunctionDeclaration =>
        node.type === TSESTree.AST_NODE_TYPES.FunctionDeclaration;
      const isFunctionExpression = (
        node: TSESTree.Node,
      ): node is TSESTree.FunctionExpression =>
        node.type === TSESTree.AST_NODE_TYPES.FunctionExpression;

      if (
        isArrowFunction(node) &&
        isVariableDeclarator(node.parent) &&
        isIdentifier(node.parent.id)
      ) {
        componentName = node.parent.id.name;
        identifierNode = node.parent.id;
      } else if (isFunctionDeclaration(node) && isIdentifier(node.id)) {
        componentName = node.id.name;
        identifierNode = node.id;
      } else if (
        isFunctionExpression(node) &&
        isVariableDeclarator(node.parent) &&
        isIdentifier(node.parent.id)
      ) {
        componentName = node.parent.id.name;
        identifierNode = node.parent.id;
      }

      if (!checkIsPascalCase(componentName)) {
        return;
      }

      const isReturningEmptyFragmentOrNull =
        // Direct return of JSX fragment, e.g., () => <></>
        (node.body.type === "JSXFragment" && node.body.children.length === 0) ||
        // Direct return of null, e.g., () => null
        (node.body.type === "Literal" && node.body.value === null) ||
        // Return JSX fragment or null from block
        (node.body.type === "BlockStatement" &&
          node.body.body.some(
            (statement) =>
              statement.type === "ReturnStatement" &&
              // Empty JSX fragment return, e.g., return <></>;
              ((statement.argument?.type === "JSXFragment" &&
                statement.argument.children.length === 0) ||
                // Empty React.Fragment return, e.g., return <React.Fragment></React.Fragment>;
                (statement.argument?.type === "JSXElement" &&
                  statement.argument.openingElement.name.type ===
                    "JSXIdentifier" &&
                  statement.argument.openingElement.name.name ===
                    "React.Fragment" &&
                  statement.argument.children.length === 0) ||
                // Literal null return, e.g., return null;
                (statement.argument?.type === "Literal" &&
                  statement.argument.value === null)),
          ));

      const hasEffectSuffix = componentName.endsWith("Effect");

      const hasEffectSuffixButIsNotEffectComponent =
        hasEffectSuffix && !isReturningEmptyFragmentOrNull;
      const isEffectComponentButDoesNotHaveEffectSuffix =
        !hasEffectSuffix && isReturningEmptyFragmentOrNull;

      if (isEffectComponentButDoesNotHaveEffectSuffix) {
        context.report({
          node,
          messageId: "effectSuffix",
          data: {
            componentName: componentName,
          },
          fix: (fixer) => {
            if (isArrowFunction(node))
              if (identifierNode) {
                return fixer.replaceText(
                  identifierNode,
                  componentName + "Effect",
                );
              }

            return null;
          },
        });
      } else if (hasEffectSuffixButIsNotEffectComponent) {
        context.report({
          node,
          messageId: "noEffectSuffix",
          data: {
            componentName: componentName,
          },
          fix: (fixer) => {
            if (identifierNode) {
              return fixer.replaceText(
                identifierNode,
                componentName.replace("Effect", ""),
              );
            }

            return null;
          },
        });
      }
    };

    return {
      ArrowFunctionExpression: checkThatNodeIsEffectComponent,
      FunctionDeclaration: checkThatNodeIsEffectComponent,
      FunctionExpression: checkThatNodeIsEffectComponent,
    };
  },
  name: "effect-components",
  meta: {
    docs: {
      description:
        "Effect components should end with the Effect suffix. This rule checks only components that are in PascalCase and that return a JSX fragment or null. Any renderProps or camelCase components are ignored.",
    },
    messages: {
      effectSuffix:
        "Effect component {{ componentName }} should end with the Effect suffix.",
      noEffectSuffix:
        "Component {{ componentName }} shouldn't end with the Effect suffix because it doesn't return a JSX fragment or null.",
    },
    type: "suggestion",
    schema: [],
    fixable: "code",
  },
  defaultOptions: [],
});

module.exports = effectComponentsRule;

export default effectComponentsRule;