first-attribute-linebreak.ts

import type { AST } from "svelte-eslint-parser"
import { createRule } from "../utils"

export default createRule("first-attribute-linebreak", {
  meta: {
    docs: {
      description: "enforce the location of first attribute",
      category: "Stylistic Issues",
      recommended: false,
      conflictWithPrettier: true,
    },
    fixable: "whitespace",
    schema: [
      {
        type: "object",
        properties: {
          multiline: { enum: ["below", "beside"] },
          singleline: { enum: ["below", "beside"] },
        },
        additionalProperties: false,
      },
    ],
    messages: {
      expected: "Expected a linebreak before this attribute.",
      unexpected: "Expected no linebreak before this attribute.",
    },
    type: "layout",
  },
  create(context) {
    const multiline: "below" | "beside" =
      context.options[0]?.multiline || "below"
    const singleline: "below" | "beside" =
      context.options[0]?.singleline || "beside"
    const sourceCode = context.getSourceCode()

    /**
     * Report attribute
     */
    function report(
      firstAttribute: AST.SvelteStartTag["attributes"][number],
      location: "below" | "beside",
    ) {
      context.report({
        node: firstAttribute,
        messageId: location === "beside" ? "unexpected" : "expected",
        fix(fixer) {
          const prevToken = sourceCode.getTokenBefore(firstAttribute, {
            includeComments: true,
          })!
          return fixer.replaceTextRange(
            [prevToken.range[1], firstAttribute.range[0]],
            location === "beside" ? " " : "\n",
          )
        },
      })
    }

    return {
      SvelteStartTag(node) {
        const firstAttribute = node.attributes[0]
        if (!firstAttribute) return

        const lastAttribute = node.attributes[node.attributes.length - 1]

        const location =
          firstAttribute.loc.start.line === lastAttribute.loc.end.line
            ? singleline
            : multiline

        if (location === "beside") {
          if (node.parent.name.loc.end.line === firstAttribute.loc.start.line) {
            return
          }
        } else {
          if (node.parent.name.loc.end.line < firstAttribute.loc.start.line) {
            return
          }
        }
        report(firstAttribute, location)
      },
    }
  },
})