Add Home Assistant connection, import, and interaction

.gitignore

@@ -15,6 +15,7 @@ package-lock.json
 
 # Testing
 coverage
+test-results/
 
 # Turbo
 .turbo

apps/editor/app/_lib/home-assistant-auth.ts

@@ -0,0 +1,150 @@
+import { randomUUID } from 'node:crypto'
+import type { NextRequest } from 'next/server'
+
+export const HOME_ASSISTANT_OAUTH_COOKIE = 'pascal_ha_oauth'
+
+export type HomeAssistantOauthCookieState = {
+  clientId: string
+  externalUrl: string | null
+  instanceUrl: string
+  redirectUri: string
+  state: string
+}
+
+export type HomeAssistantTokenResponse = {
+  access_token: string
+  expires_in: number
+  refresh_token?: string
+  token_type: string
+}
+
+function normalizeUrlValue(value: string) {
+  return value.trim().replace(/\/$/, '')
+}
+
+export function normalizeHomeAssistantUrl(value: string) {
+  const normalized = normalizeUrlValue(value)
+  const url = new URL(normalized)
+  if (!(url.protocol === 'http:' || url.protocol === 'https:')) {
+    throw new Error('Home Assistant URL must use http or https.')
+  }
+  return url.toString().replace(/\/$/, '')
+}
+
+export function normalizeOptionalHomeAssistantUrl(value: string | null | undefined) {
+  if (!value || value.trim().length === 0) {
+    return null
+  }
+  return normalizeHomeAssistantUrl(value)
+}
+
+export function getRequestOrigin(request: NextRequest) {
+  const forwardedHost = request.headers.get('x-forwarded-host')
+  const forwardedProto = request.headers.get('x-forwarded-proto')
+  if (forwardedHost && forwardedProto) {
+    return `${forwardedProto}://${forwardedHost}`
+  }
+  return request.nextUrl.origin
+}
+
+export function buildHomeAssistantOauthState(
+  request: NextRequest,
+  instanceUrl: string,
+  externalUrl: string | null,
+): HomeAssistantOauthCookieState {
+  const clientId = getRequestOrigin(request)
+  return {
+    clientId,
+    externalUrl,
+    instanceUrl,
+    redirectUri: `${clientId}/api/home-assistant/oauth/callback`,
+    state: randomUUID(),
+  }
+}
+
+function getOauthBaseUrl(
+  oauthState: Pick<HomeAssistantOauthCookieState, 'externalUrl' | 'instanceUrl'>,
+) {
+  return oauthState.externalUrl ?? oauthState.instanceUrl
+}
+
+export function buildHomeAssistantAuthorizeUrl(oauthState: HomeAssistantOauthCookieState) {
+  const authorizeUrl = new URL('/auth/authorize', getOauthBaseUrl(oauthState))
+  authorizeUrl.searchParams.set('client_id', oauthState.clientId)
+  authorizeUrl.searchParams.set('redirect_uri', oauthState.redirectUri)
+  authorizeUrl.searchParams.set('state', oauthState.state)
+  return authorizeUrl.toString()
+}
+
+function buildTokenRequestBody(params: Record<string, string>) {
+  const body = new URLSearchParams()
+  for (const [key, value] of Object.entries(params)) {
+    body.set(key, value)
+  }
+  return body
+}
+
+async function readTokenResponse(response: Response) {
+  const payload = (await response.json()) as
+    | HomeAssistantTokenResponse
+    | {
+        error?: string
+        error_description?: string
+      }
+
+  if (!response.ok) {
+    const errorPayload = 'access_token' in payload ? null : payload
+    throw new Error(
+      errorPayload?.error_description ||
+        errorPayload?.error ||
+        'Home Assistant token request failed.',
+    )
+  }
+
+  return payload as HomeAssistantTokenResponse
+}
+
+export async function exchangeAuthorizationCode(
+  instanceUrl: string,
+  clientId: string,
+  code: string,
+  externalUrl?: string | null,
+) {
+  const tokenUrl = new URL('/auth/token', externalUrl ?? instanceUrl)
+  const response = await fetch(tokenUrl, {
+    body: buildTokenRequestBody({
+      client_id: clientId,
+      code,
+      grant_type: 'authorization_code',
+    }),
+    cache: 'no-store',
+    headers: {
+      'Content-Type': 'application/x-www-form-urlencoded',
+    },
+    method: 'POST',
+  })
+
+  return readTokenResponse(response)
+}
+
+export async function refreshHomeAssistantAccessToken(
+  instanceUrl: string,
+  clientId: string,
+  refreshToken: string,
+) {
+  const tokenUrl = new URL('/auth/token', instanceUrl)
+  const response = await fetch(tokenUrl, {
+    body: buildTokenRequestBody({
+      client_id: clientId,
+      grant_type: 'refresh_token',
+      refresh_token: refreshToken,
+    }),
+    cache: 'no-store',
+    headers: {
+      'Content-Type': 'application/x-www-form-urlencoded',
+    },
+    method: 'POST',
+  })
+
+  return readTokenResponse(response)
+}