rollup.dts.config.js

// @ts-check
import assert from 'node:assert/strict'
import { parse } from '@babel/parser'
import { existsSync, readFileSync, readdirSync, writeFileSync } from 'node:fs'
import MagicString from 'magic-string'
import dts from 'rollup-plugin-dts'

if (!existsSync('temp/packages')) {
  console.warn(
    'no temp dts files found. run `tsc -p tsconfig.build.json` first.',
  )
  process.exit(1)
}

const packages = readdirSync('temp/packages')
const targets = process.env.TARGETS ? process.env.TARGETS.split(',') : null
const targetPackages = targets
  ? packages.filter(pkg => targets.includes(pkg))
  : packages

export default targetPackages.map(
  /** @returns {import('rollup').RollupOptions} */
  pkg => {
    return {
      input: `./temp/packages/${pkg}/src/index.d.ts`,
      output: {
        file: `packages/${pkg}/dist/${pkg}.d.ts`,
        format: 'es',
      },
      plugins: [dts(), patchTypes(pkg), ...(pkg === 'vue' ? [copyMts()] : [])],
      onwarn(warning, warn) {
        // during dts rollup, everything is externalized by default
        if (
          warning.code === 'UNRESOLVED_IMPORT' &&
          !warning.exporter?.startsWith('.')
        ) {
          return
        }
        warn(warning)
      },
    }
  },
)

/**
 * Patch the dts generated by rollup-plugin-dts
 * 1. Convert all types to inline exports
 *    and remove them from the big export {} declaration
 *    otherwise it gets weird in vitepress `defineComponent` call with
 *    "the inferred type cannot be named without a reference"
 * 2. Append custom augmentations (jsx, macros)
 *
 * @param {string} pkg
 * @returns {import('rollup').Plugin}
 */
function patchTypes(pkg) {
  return {
    name: 'patch-types',
    renderChunk(code, chunk) {
      const s = new MagicString(code)
      const ast = parse(code, {
        plugins: ['typescript'],
        sourceType: 'module',
      })

      /**
       * @param {import('@babel/types').VariableDeclarator | import('@babel/types').TSTypeAliasDeclaration | import('@babel/types').TSInterfaceDeclaration | import('@babel/types').TSDeclareFunction | import('@babel/types').TSInterfaceDeclaration | import('@babel/types').TSEnumDeclaration | import('@babel/types').ClassDeclaration} node
       * @param {import('@babel/types').VariableDeclaration} [parentDecl]
       */
      function processDeclaration(node, parentDecl) {
        if (!node.id) {
          return
        }
        assert(node.id.type === 'Identifier')
        const name = node.id.name
        if (name.startsWith('_')) {
          return
        }
        shouldRemoveExport.add(name)
        if (isExported.has(name)) {
          const start = (parentDecl || node).start
          assert(typeof start === 'number')
          s.prependLeft(start, `export `)
        }
      }

      const isExported = new Set()
      const shouldRemoveExport = new Set()

      // pass 0: check all exported types
      for (const node of ast.program.body) {
        if (node.type === 'ExportNamedDeclaration' && !node.source) {
          for (let i = 0; i < node.specifiers.length; i++) {
            const spec = node.specifiers[i]
            if (spec.type === 'ExportSpecifier') {
              isExported.add(spec.local.name)
            }
          }
        }
      }

      // pass 1: add exports
      for (const node of ast.program.body) {
        if (node.type === 'VariableDeclaration') {
          processDeclaration(node.declarations[0], node)
          if (node.declarations.length > 1) {
            assert(typeof node.start === 'number')
            assert(typeof node.end === 'number')
            throw new Error(
              `unhandled declare const with more than one declarators:\n${code.slice(
                node.start,
                node.end,
              )}`,
            )
          }
        } else if (
          node.type === 'TSTypeAliasDeclaration' ||
          node.type === 'TSInterfaceDeclaration' ||
          node.type === 'TSDeclareFunction' ||
          node.type === 'TSEnumDeclaration' ||
          node.type === 'ClassDeclaration'
        ) {
          processDeclaration(node)
        }
      }

      // pass 2: remove exports
      for (const node of ast.program.body) {
        if (node.type === 'ExportNamedDeclaration' && !node.source) {
          let removed = 0
          for (let i = 0; i < node.specifiers.length; i++) {
            const spec = node.specifiers[i]
            if (
              spec.type === 'ExportSpecifier' &&
              shouldRemoveExport.has(spec.local.name)
            ) {
              assert(spec.exported.type === 'Identifier')
              const exported = spec.exported.name
              if (exported !== spec.local.name) {
                // this only happens if we have something like
                //   type Foo
                //   export { Foo as Bar }
                continue
              }
              const next = node.specifiers[i + 1]
              if (next) {
                assert(typeof spec.start === 'number')
                assert(typeof next.start === 'number')
                s.remove(spec.start, next.start)
              } else {
                // last one
                const prev = node.specifiers[i - 1]
                assert(typeof spec.start === 'number')
                assert(typeof spec.end === 'number')
                s.remove(
                  prev
                    ? (assert(typeof prev.end === 'number'), prev.end)
                    : spec.start,
                  spec.end,
                )
              }
              removed++
            }
          }
          if (removed === node.specifiers.length) {
            assert(typeof node.start === 'number')
            assert(typeof node.end === 'number')
            s.remove(node.start, node.end)
          }
        }
      }
      code = s.toString()

      // append pkg specific types
      const additionalTypeDir = `packages/${pkg}/types`
      if (existsSync(additionalTypeDir)) {
        code +=
          '\n' +
          readdirSync(additionalTypeDir)
            .map(file => readFileSync(`${additionalTypeDir}/${file}`, 'utf-8'))
            .join('\n')
      }
      return code
    },
  }
}

/**
 * According to https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-7.html#packagejson-exports-imports-and-self-referencing
 * the only way to correct provide types for both Node ESM and CJS is to have
 * two separate declaration files, so we need to copy vue.d.ts to vue.d.mts
 * upon build.
 *
 * @returns {import('rollup').Plugin}
 */
function copyMts() {
  return {
    name: 'copy-vue-mts',
    writeBundle(_, bundle) {
      assert('code' in bundle['vue.d.ts'])
      writeFileSync('packages/vue/dist/vue.d.mts', bundle['vue.d.ts'].code)
    },
  }
}