Add ChatGPT login flow

core/app/src/main/java/com/tom/rv2ide/artificial/login/CodexLoginManager.kt

@@ -0,0 +1,337 @@
+package com.tom.rv2ide.artificial.login
+
+import android.app.Activity
+import android.content.ActivityNotFoundException
+import android.content.Context
+import android.content.Intent
+import android.net.Uri
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.coroutineContext
+import kotlinx.coroutines.ensureActive
+import kotlinx.coroutines.withContext
+import kotlinx.coroutines.withTimeout
+import okhttp3.MediaType.Companion.toMediaType
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.RequestBody.Companion.toRequestBody
+import org.json.JSONObject
+import java.io.BufferedReader
+import java.io.IOException
+import java.io.InputStreamReader
+import java.io.OutputStream
+import java.io.OutputStreamWriter
+import java.net.BindException
+import java.net.InetAddress
+import java.net.InetSocketAddress
+import java.net.ServerSocket
+import java.net.Socket
+import java.net.SocketTimeoutException
+import java.net.URLEncoder
+import java.nio.charset.StandardCharsets
+import java.security.MessageDigest
+import java.security.SecureRandom
+import java.util.Base64
+import java.util.concurrent.TimeUnit
+
+class CodexLoginManager {
+  companion object {
+    private const val CLIENT_ID = "app_EMoamEEZ73f0CkXaXp7hrann"
+    private const val AUTHORIZATION_URL = "https://auth.openai.com/oauth/authorize"
+    private const val TOKEN_URL = "https://auth.openai.com/oauth/token"
+    private const val CALLBACK_PATH = "/auth/callback"
+    private const val LOOPBACK_HOST = "127.0.0.1"
+    private const val DEFAULT_PORT = 1455
+    private const val CALLBACK_TIMEOUT_MS = 180_000L
+    private const val RESPONSE_BODY_CHARSET = "utf-8"
+    private const val ORIGINATOR_VALUE = "codex_cli_rs"
+    private val SCOPE_STRING = listOf(
+      "openid",
+      "profile",
+      "email",
+      "offline_access",
+      "api.connectors.read",
+      "api.connectors.invoke"
+    ).joinToString(" ")
+  }
+
+  private val httpClient = OkHttpClient.Builder()
+    .connectTimeout(30, TimeUnit.SECONDS)
+    .readTimeout(30, TimeUnit.SECONDS)
+    .writeTimeout(30, TimeUnit.SECONDS)
+    .build()
+
+  @Throws(IOException::class)
+  suspend fun loginWithChatGPT(context: Context): String {
+    val pkce = createPkceCodes()
+    val state = generateState()
+    val (serverSocket, actualPort) = createServerSocket()
+    val redirectUri = "http://$LOOPBACK_HOST:$actualPort$CALLBACK_PATH"
+    val authUrl = buildAuthorizationUrl(redirectUri, pkce, state)
+
+    try {
+      withContext(Dispatchers.Main) {
+        openBrowser(context, authUrl)
+      }
+
+      val callback = withTimeout(CALLBACK_TIMEOUT_MS) {
+        waitForCallback(serverSocket, state)
+      }
+
+      callback.error?.let {
+        throw IllegalStateException(callback.errorDescription ?: it)
+      }
+
+      val code = callback.code ?: throw IllegalStateException("Missing authorization code from ChatGPT login.")
+      val tokens = exchangeCodeForTokens(code, redirectUri, pkce)
+      return exchangeIdTokenForApiKey(tokens.idToken)
+    } finally {
+      try {
+        serverSocket.close()
+      } catch (_: IOException) {
+      }
+    }
+  }
+
+  private fun createServerSocket(): Pair<ServerSocket, Int> {
+    val server = ServerSocket()
+    server.reuseAddress = true
+    try {
+      server.bind(InetSocketAddress(InetAddress.getByName(LOOPBACK_HOST), DEFAULT_PORT))
+    } catch (bindException: BindException) {
+      server.bind(InetSocketAddress(InetAddress.getByName(LOOPBACK_HOST), 0))
+    }
+    return server to server.localPort
+  }
+
+  private fun buildAuthorizationUrl(redirectUri: String, pkce: PkceCodes, state: String): String {
+    val params = listOf(
+      "response_type" to "code",
+      "client_id" to CLIENT_ID,
+      "redirect_uri" to redirectUri,
+      "scope" to SCOPE_STRING,
+      "code_challenge" to pkce.codeChallenge,
+      "code_challenge_method" to "S256",
+      "id_token_add_organizations" to "true",
+      "codex_cli_simplified_flow" to "true",
+      "state" to state,
+      "originator" to ORIGINATOR_VALUE
+    )
+
+    val encoded = params.joinToString("&") { "${it.first}=${urlEncode(it.second)}" }
+    return "$AUTHORIZATION_URL?$encoded"
+  }
+
+  private fun urlEncode(value: String): String {
+    return URLEncoder.encode(value, StandardCharsets.UTF_8.name()).replace("+", "%20")
+  }
+
+  private fun openBrowser(context: Context, authUrl: String) {
+    val intent = Intent(Intent.ACTION_VIEW, Uri.parse(authUrl))
+    if (context !is Activity) {
+      intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK)
+    }
+    try {
+      context.startActivity(intent)
+    } catch (error: ActivityNotFoundException) {
+      throw IllegalStateException("No browser found to complete the ChatGPT login.", error)
+    }
+  }
+
+  private suspend fun waitForCallback(server: ServerSocket, expectedState: String): CallbackResult {
+    return withContext(Dispatchers.IO) {
+      server.soTimeout = 1_000
+      while (true) {
+        coroutineContext.ensureActive()
+        try {
+          val socket = server.accept()
+          val callback = handleSocket(socket, expectedState)
+          if (callback != null) {
+            return@withContext callback
+          }
+        } catch (socketTimeout: SocketTimeoutException) {
+          continue
+        }
+      }
+    }
+  }
+
+  private fun handleSocket(socket: Socket, expectedState: String): CallbackResult? {
+    socket.use {
+      val reader = BufferedReader(InputStreamReader(it.getInputStream()))
+      val requestLine = reader.readLine() ?: return null
+      val segments = requestLine.split(" ")
+      if (segments.size < 2) {
+        drainRequest(reader)
+        sendHttpResponse(it.getOutputStream(), 400, "Invalid request")
+        return null
+      }
+
+      val target = segments[1]
+      val uri = Uri.parse("http://$LOOPBACK_HOST$target")
+      val path = uri.path ?: ""
+      drainRequest(reader)
+
+      if (path != CALLBACK_PATH) {
+        sendHttpResponse(it.getOutputStream(), 404, "<html><body><h1>Not found</h1></body></html>")
+        return null
+      }
+
+      val code = uri.getQueryParameter("code")
+      val state = uri.getQueryParameter("state")
+      val error = uri.getQueryParameter("error")
+      val errorDescription = uri.getQueryParameter("error_description")
+      val body = when {
+        error != null -> buildErrorPage(errorDescription ?: "An error occurred")
+        code != null -> buildSuccessPage()
+        else -> buildErrorPage("Missing authorization code")
+      }
+      sendHttpResponse(it.getOutputStream(), 200, body)
+
+      if (error != null) {
+        return CallbackResult(null, state, error, errorDescription)
+      }
+
+      if (state != expectedState) {
+        return CallbackResult(null, state, "State mismatch", "The login response does not match the request state.")
+      }
+
+      return CallbackResult(code, state, null, null)
+    }
+  }
+
+  private fun drainRequest(reader: BufferedReader) {
+    while (true) {
+      val line = reader.readLine() ?: break
+      if (line.isEmpty()) {
+        break
+      }
+    }
+  }
+
+  private fun sendHttpResponse(output: OutputStream, statusCode: Int, body: String) {
+    val payload = body.toByteArray(StandardCharsets.UTF_8)
+    OutputStreamWriter(output, StandardCharsets.UTF_8).use { writer ->
+      writer.write("HTTP/1.1 $statusCode ${statusText(statusCode)}\r\n")
+      writer.write("Content-Type: text/html; charset=$RESPONSE_BODY_CHARSET\r\n")
+      writer.write("Content-Length: ${payload.size}\r\n")
+      writer.write("Connection: close\r\n")
+      writer.write("\r\n")
+      writer.flush()
+      output.write(payload)
+      output.flush()
+    }
+  }
+
+  private fun statusText(code: Int): String = when (code) {
+    200 -> "OK"
+    400 -> "Bad Request"
+    404 -> "Not Found"
+    else -> "OK"
+  }
+
+
+  private fun buildErrorPage(message: String): String {
+    return """
+      |<html>
+      |<head><title>Login error</title></head>
+      |<body>
+      |  <h1>Unable to complete login</h1>
+      |  <p>${message}</p>
+      |</body>
+      |</html>
+      |""".trimMargin()
+  }
+
+  private suspend fun exchangeCodeForTokens(code: String, redirectUri: String, pkce: PkceCodes): ExchangedTokens {
+    return withContext(Dispatchers.IO) {
+      val body = "grant_type=authorization_code&code=${urlEncode(code)}&redirect_uri=${urlEncode(redirectUri)}&client_id=${urlEncode(CLIENT_ID)}&code_verifier=${urlEncode(pkce.codeVerifier)}"
+      val request = Request.Builder()
+        .url(TOKEN_URL)
+        .header("Content-Type", "application/x-www-form-urlencoded")
+        .post(body.toRequestBody("application/x-www-form-urlencoded".toMediaType()))
+        .build()
+
+      val response = httpClient.newCall(request).execute()
+      response.use { resp ->
+        val responseBody = resp.body?.string().orEmpty()
+        if (!resp.isSuccessful) {
+          throw IOException("Token exchange failed: ${resp.code} - $responseBody")
+        }
+        val json = JSONObject(responseBody)
+        val idToken = json.optString("id_token")
+        val accessToken = json.optString("access_token")
+        val refreshToken = json.optString("refresh_token")
+        if (idToken.isBlank()) {
+          throw IllegalStateException("Token exchange did not return an id_token")
+        }
+        return@withContext ExchangedTokens(idToken, accessToken, refreshToken)
+      }
+    }
+  }
+
+  private suspend fun exchangeIdTokenForApiKey(idToken: String): String {
+    return withContext(Dispatchers.IO) {
+      val form = "grant_type=${urlEncode("urn:ietf:params:oauth:grant-type:token-exchange")}&client_id=${urlEncode(CLIENT_ID)}&requested_token=${urlEncode("openai-api-key")}&subject_token=${urlEncode(idToken)}&subject_token_type=${urlEncode("urn:ietf:params:oauth:token-type:id_token")}" 
+      val request = Request.Builder()
+        .url(TOKEN_URL)
+        .header("Content-Type", "application/x-www-form-urlencoded")
+        .post(form.toRequestBody("application/x-www-form-urlencoded".toMediaType()))
+        .build()
+
+      val response = httpClient.newCall(request).execute()
+      response.use { resp ->
+        val body = resp.body?.string().orEmpty()
+        if (!resp.isSuccessful) {
+          throw IOException("API key exchange failed: ${resp.code} - $body")
+        }
+        val json = JSONObject(body)
+        return@withContext json.getString("access_token")
+      }
+    }
+  }
+
+  private fun generateState(): String {
+    val bytes = ByteArray(32)
+    SecureRandom().nextBytes(bytes)
+    return Base64.getUrlEncoder().withoutPadding().encodeToString(bytes)
+  }
+  private fun createPkceCodes(): PkceCodes {
+    val random = SecureRandom()
+    val verifierBytes = ByteArray(32)
+    random.nextBytes(verifierBytes)
+    val verifier = Base64.getUrlEncoder().withoutPadding().encodeToString(verifierBytes)
+    val digest = MessageDigest.getInstance("SHA-256").digest(verifier.toByteArray(StandardCharsets.US_ASCII))
+    val challenge = Base64.getUrlEncoder().withoutPadding().encodeToString(digest)
+    return PkceCodes(verifier, challenge)
+  }
+
+  private data class CallbackResult(
+    val code: String?,
+    val state: String?,
+    val error: String?,
+    val errorDescription: String?
+  )
+
+  private data class ExchangedTokens(
+    val idToken: String,
+    val accessToken: String,
+    val refreshToken: String
+  )
+
+  private data class PkceCodes(
+    val codeVerifier: String,
+    val codeChallenge: String
+  )
+
+  private fun buildSuccessPage(): String {
+    return """
+      |<html>
+      |<head><meta charset=\"utf-8\"/><title>Login complete</title></head>
+      |<body>
+      |  <h1>Login completed</h1>
+      |  <p>The chat login completed successfully. Close this tab to return to the IDE.</p>
+      |</body>
+      |</html>
+      |""".trimMargin()
+  }
+}