import * as utils from "../../utils";
import type {
  RuleFix,
  RuleListener
} from "@typescript-eslint/utils/dist/ts-eslint";
import { a, s } from "typescript-misc";

export enum MessageId {
  addEmptyLine = "addEmptyLine",
  removeEmptyLine = "removeEmptyLine"
}

export const switchCaseSpacing = utils.createRule({
  name: "switch-case-spacing",
  fixable: utils.Fixable.whitespace,
  messages: {
    [MessageId.addEmptyLine]: "Add empty line before switch case",
    [MessageId.removeEmptyLine]: "Remove empty line before switch case"
  },
  docs: {
    description:
      "Ensures consistent empty lines between switch case statements.",
    failExamples: `
      switch (x) {
        case 1:

        case 2:
          break;
        case 3:
      }
    `,
    passExamples: `
      switch (x) {
        case 1:
        case 2:
          break;

        case 3:
      }
    `
  },
  create: (context): RuleListener => {
    return {
      SwitchStatement: node => {
        for (const [case1, case2] of a.chain(node.cases)) {
          const fallThrough = case1.consequent.length === 0;

          const range = context.getLeadingSpaces(case2);

          const got = context.getText(range);

          const expected =
            context.eol.repeat(fallThrough ? 1 : 2) +
            s.trimLeadingEmptyLines(got);

          if (got === expected) {
            // Valid
          } else
            context.report({
              fix: (): RuleFix => {
                return { range, text: expected };
              },
              messageId: fallThrough
                ? MessageId.removeEmptyLine
                : MessageId.addEmptyLine,
              node: case2
            });
        }
      }
    };
  }
});