import type { MetaQuery } from "@refinedev/core";
import { type DocumentNode, visit, type SelectionSetNode } from "graphql";

export const getOperationFields = (documentNode: DocumentNode) => {
  const fieldLines: string[] = [];
  let isInitialEnter = true;
  let depth = 0;
  let isNestedField = false;

  // remove `<name>_aggregate` or `<name>Aggregate` object from query
  const newDocumentNode = visit(documentNode, {
    Field: {
      enter(node) {
        if (
          node.name.value.includes("aggregate") ||
          node.name.value.includes("Aggregate")
        ) {
          return null;
        }

        return node;
      },
    },
  });

  visit(newDocumentNode, {
    Field: {
      enter(node): SelectionSetNode | void {
        if (isInitialEnter) {
          isInitialEnter = false;

          if (typeof node.selectionSet === "undefined") {
            throw new Error("Operation must have a selection set");
          }

          return node.selectionSet;
        }

        fieldLines.push(
          `${depth > 0 ? "  ".repeat(isNestedField ? depth : depth - 1) : ""}${
            node.name.value
          }${node.selectionSet ? " {" : ""}`,
        );

        if (node.selectionSet) {
          depth++;
          isNestedField = true;
        }
      },
      leave(node) {
        if (node.selectionSet) {
          depth--;
          fieldLines.push(`${"  ".repeat(depth)}}`);
          isNestedField = false;
        }
      },
    },
  });

  return fieldLines.join("\n").trim();
};

export const isMutation = (documentNode: DocumentNode) => {
  let isMutation = false;

  visit(documentNode, {
    OperationDefinition: {
      enter(node) {
        if (node.operation === "mutation") {
          isMutation = true;
        }
      },
    },
  });

  return isMutation;
};

export const metaFieldsToGqlFields = (metaFields: MetaQuery["fields"]) => {
  if (!metaFields) return "";

  const fields: string[] = [];

  metaFields.forEach((field) => {
    if (typeof field === "string") {
      fields.push(field);
    } else {
      const [key, value] = Object.entries(field)[0];
      fields.push(`${key} { ${metaFieldsToGqlFields(value)} }`);
    }
  });

  return fields.join("\n");
};