experimental-require-strict-events.ts

import type { AST } from "svelte-eslint-parser"

import { createRule } from "../utils"
import { findAttribute, getLangValue } from "../utils/ast-utils"

const EVENTS_TYPE_NAME = "$$Events"

export default createRule("experimental-require-strict-events", {
  meta: {
    docs: {
      description: "require the strictEvents attribute on `<script>` tags",
      category: "Experimental",
      recommended: false,
    },
    schema: [],
    messages: {
      missingStrictEvents: `The component must have the strictEvents attribute on its <script> tag or it must define the $$Events interface.`,
    },
    type: "suggestion",
  },
  create(context) {
    let isTs = false
    let hasAttribute = false
    let hasDeclaredEvents = false
    let scriptNode: AST.SvelteScriptElement
    return {
      SvelteScriptElement(node) {
        const lang = getLangValue(node)?.toLowerCase()
        isTs = lang === "ts" || lang === "typescript"
        hasAttribute = findAttribute(node, "strictEvents") !== null
        scriptNode = node
      },
      TSInterfaceDeclaration(node) {
        if (node.id.name === EVENTS_TYPE_NAME) {
          hasDeclaredEvents = true
        }
      },
      TSTypeAliasDeclaration(node) {
        if (node.id.name === EVENTS_TYPE_NAME) {
          hasDeclaredEvents = true
        }
      },
      "Program:exit"() {
        if (isTs && !hasAttribute && !hasDeclaredEvents) {
          context.report({
            node: scriptNode,
            messageId: "missingStrictEvents",
          })
        }
      },
    }
  },
})