// @effect-diagnostics-next-line nodeBuiltinImport:off - Effect's symlink has no type argument, and Windows needs a junction to link without elevation.
import * as NodeFSP from "node:fs/promises";

import type { AntigravityAuthMethod, ProviderInstanceId } from "@t3tools/contracts";
import * as HostProcess from "@t3tools/shared/HostProcess";
import { resolveNodeExecutable, nodeRuntimeUnavailableMessage } from "@t3tools/shared/nodeRuntime";
import * as Digest from "effect/crypto/Digest";
import * as Effect from "effect/Effect";
import * as Hex from "effect/encoding/Hex";
import * as FileSystem from "effect/FileSystem";
import * as Path from "effect/Path";
import type * as PlatformError from "effect/PlatformError";
import * as Schema from "effect/Schema";
import * as Stream from "effect/Stream";
import * as ChildProcess from "effect/process/ChildProcess";
import * as ChildProcessSpawner from "effect/process/ChildProcessSpawner";
import * as AcpErrors from "effect-acp/errors";

import { collectUint8StreamText } from "@t3tools/provider-core/server/collectStreamText";
import type * as AcpSessionRuntime from "@t3tools/provider-acp/server/AcpSessionRuntime";
import {
  antigravityUserSkillDirectories,
  resolveAntigravityUserHome,
} from "./Drivers/AntigravitySkills.ts";

export const ANTIGRAVITY_AUTH_STDOUT_PREFIX =
  "Open the following link to authenticate the ACP server: ";
export const ANTIGRAVITY_AUTH_BROWSER_MARKER = "__T3_ANTIGRAVITY_AUTH_URL__";
export const ANTIGRAVITY_SIGN_IN_REQUIRED_MESSAGE =
  "Sign in to Antigravity in Settings before you continue.";

const maxAuthorizationUrlLength = 16_384;
const maxBrowserHelperLineLength =
  Math.max(ANTIGRAVITY_AUTH_BROWSER_MARKER.length, ANTIGRAVITY_AUTH_STDOUT_PREFIX.length) +
  maxAuthorizationUrlLength +
  2;
const maxStdoutLineBytes = 16 * 1024 * 1024;
const authPrefixBytes = new TextEncoder().encode(ANTIGRAVITY_AUTH_STDOUT_PREFIX);
const decodeUrl = Schema.decodeUnknownEffect(Schema.URLFromString);
const decodeBrowserHelperUrl = Schema.decodeUnknownEffect(Schema.fromJsonString(Schema.String));
const ProfileSettingsFile = Schema.Struct({
  auth: Schema.Struct({ type: Schema.String }),
  gcp: Schema.optional(
    Schema.Struct({
      project: Schema.optional(Schema.String),
      location: Schema.optional(Schema.String),
    }),
  ),
});
const encodeProfileSettings = Schema.encodeSync(Schema.fromJsonString(ProfileSettingsFile));
const isAcpRequestError = Schema.is(AcpErrors.AcpRequestError);
const isAcpTransportError = Schema.is(AcpErrors.AcpTransportError);

// Python splits BROWSER on path separators before parsing quotes. Exit 0 on EPIPE to prevent browser fallback after cancellation.
const browserHelperSource =
  `process.stderr.on("error",()=>process.exit(0)).write(` +
  `"${ANTIGRAVITY_AUTH_BROWSER_MARKER}"+JSON.stringify(process.argv[1])+"\\n",` +
  `()=>process.exit(0))`;
const browserPreflightUrl = "https://example.invalid/t3-antigravity-browser-preflight";

const removedEnvironmentKeys = new Set([
  "GEMINI_API_KEY",
  "GOOGLE_API_KEY",
  "GOOGLE_APPLICATION_CREDENTIALS",
  "GOOGLE_CLOUD_PROJECT",
  "GOOGLE_CLOUD_LOCATION",
  "GOOGLE_CLOUD_QUOTA_PROJECT",
  "GOOGLE_GENAI_USE_VERTEXAI",
  "GCLOUD_PROJECT",
  "CLOUDSDK_CORE_PROJECT",
  "AGY_ACP_CCPA_PROJECT",
  "AGY_ACP_ENABLE_OAUTH",
  "GEMINI_HOME",
  "AGY_ACP_FORCE_FILE_STORAGE",
  "ANTIGRAVITY_HARNESS_PATH",
  "BROWSER",
  "PYTHONUNBUFFERED",
  "ELECTRON_RUN_AS_NODE",
]);

export interface AntigravityProfile {
  readonly platform: NodeJS.Platform;
  readonly geminiHome: string;
  readonly acpDirectory: string;
  readonly tokenPath: string;
  readonly tempDirectory: string;
  readonly browserCommand: string;
  readonly caBundlePath?: string;
}

export interface AntigravityAuthConfig {
  readonly authMethod: AntigravityAuthMethod;
  readonly apiKey: string;
  readonly gcpProject: string;
  readonly gcpLocation: string;
}

const ANTIGRAVITY_PERSONAL_AUTH: AntigravityAuthConfig = {
  authMethod: "oauth-personal",
  apiKey: "",
  gcpProject: "",
  gcpLocation: "",
};

export function antigravityAuthUsesBrowser(authMethod: AntigravityAuthMethod): boolean {
  return authMethod === "oauth-personal" || authMethod === "oauth-business";
}

export function antigravityAuthLabel(authMethod: AntigravityAuthMethod): string {
  switch (authMethod) {
    case "oauth-personal":
      return "Google account";
    case "oauth-business":
      return "Gemini Enterprise";
    case "gemini-api-key":
      return "Gemini API key";
    case "agent-platform":
      return "Agent Platform";
  }
}

export function antigravityAuthConfigIssue(auth: AntigravityAuthConfig): string | null {
  switch (auth.authMethod) {
    case "oauth-personal":
      return null;
    case "oauth-business":
      return auth.gcpProject && auth.gcpLocation
        ? null
        : "Gemini Enterprise needs a GCP project and location in the Antigravity provider settings.";
    case "gemini-api-key":
      return auth.apiKey ? null : "Enter a Gemini API key in the Antigravity provider settings.";
    case "agent-platform":
      return auth.apiKey || (auth.gcpProject && auth.gcpLocation)
        ? null
        : "Agent Platform needs an API key, or a GCP project and location, in the Antigravity provider settings.";
  }
}

/**
 * `auth.type` names the selected method so a native logout clears only that method's credentials
 * instead of every stored token. Never holds a credential.
 */
function antigravityProfileSettings(auth: AntigravityAuthConfig): string {
  const gcp = {
    ...(auth.gcpProject ? { project: auth.gcpProject } : {}),
    ...(auth.gcpLocation ? { location: auth.gcpLocation } : {}),
  };
  return `${encodeProfileSettings({
    auth: { type: auth.authMethod },
    ...(Object.keys(gcp).length > 0 ? { gcp } : {}),
  })}\n`;
}

export interface AntigravityAuthorizationUrl {
  readonly authorizationUrl: string;
  readonly redirectUri: string;
  readonly state: string;
}

function authSupportError(detail: string) {
  return new AcpErrors.AcpTransportError({ detail, cause: undefined });
}

export function isAntigravitySignInRequiredError(error: unknown): boolean {
  return (
    (isAcpRequestError(error) && error.code === -32000) ||
    (isAcpTransportError(error) && error.detail === ANTIGRAVITY_SIGN_IN_REQUIRED_MESSAGE)
  );
}

export interface AntigravityInstanceDirectories {
  readonly profile: string;
  /** Keep beside the profile: 120-character archive members under its longer name would exceed Windows' 260-character limit. */
  readonly runtimeTemp: string;
}

/** Hashes the instance ID so case-only differences stay separate on case-insensitive filesystems. */
export const resolveAntigravityInstanceDirectories = Effect.fn(
  "resolveAntigravityInstanceDirectories",
)(function* (stateDir: string, instanceId: ProviderInstanceId) {
  const digest = yield* Digest.Digest;
  const path = yield* Path.Path;
  const key = Hex.encode(yield* digest.digest(Digest.sha256, new TextEncoder().encode(instanceId)));
  return {
    profile: path.join(stateDir, "providers", "antigravity", key),
    runtimeTemp: path.join(stateDir, "antigravity-tmp", key.slice(0, 12)),
  } satisfies AntigravityInstanceDirectories;
});

function quoteBrowserArgument(value: string): string {
  return `'${value.replaceAll("'", `'"'"'`)}'`;
}

function antigravityEnvironment(
  profile: AntigravityProfile,
  baseEnv: NodeJS.ProcessEnv,
  auth: AntigravityAuthConfig,
  runtimeTempDirectory?: string,
) {
  // Application Default Credentials are the selected credential here, not an ambient override.
  const usesApplicationDefaultCredentials = auth.authMethod === "agent-platform" && !auth.apiKey;
  const environment: NodeJS.ProcessEnv = {};
  for (const [key, value] of Object.entries(baseEnv)) {
    // Windows treats environment keys as case-insensitive. Remove aliases too.
    const name = key.toUpperCase();
    if (
      !removedEnvironmentKeys.has(name) ||
      (usesApplicationDefaultCredentials && name === "GOOGLE_APPLICATION_CREDENTIALS")
    ) {
      environment[key] = value;
    }
  }
  // Put the GCP pair in settings.json because GOOGLE_API_KEY takes precedence in the environment.
  const credential =
    auth.authMethod === "gemini-api-key" && auth.apiKey
      ? { GEMINI_API_KEY: auth.apiKey }
      : auth.authMethod === "agent-platform" && auth.apiKey
        ? { GOOGLE_API_KEY: auth.apiKey }
        : {};
  // Each launch unpacks about 1 GB; use T3-owned temp so the driver can reclaim files after force-kill.
  const tempDirectory = runtimeTempDirectory ?? profile.tempDirectory;
  return {
    ...environment,
    ...credential,
    ...(profile.caBundlePath !== undefined &&
    baseEnv.SSL_CERT_FILE === undefined &&
    baseEnv.SSL_CERT_DIR === undefined
      ? { SSL_CERT_FILE: profile.caBundlePath }
      : {}),
    GEMINI_HOME: profile.geminiHome,
    AGY_ACP_FORCE_FILE_STORAGE: "1",
    BROWSER: profile.browserCommand,
    PYTHONUNBUFFERED: "1",
    ELECTRON_RUN_AS_NODE: "1",
    ...(profile.platform === "win32"
      ? { TEMP: tempDirectory, TMP: tempDirectory }
      : { TMPDIR: tempDirectory }),
  };
}

/** Private GEMINI_HOME isolates credentials/hooks/MCP; link global skills from the real ~/.gemini. */
const linkAntigravityUserSkills = Effect.fn("linkAntigravityUserSkills")(function* (input: {
  readonly profileDirectory: string;
  readonly userHome: string;
  readonly platform: NodeJS.Platform;
}): Effect.fn.Return<void, never, FileSystem.FileSystem | Path.Path> {
  const fs = yield* FileSystem.FileSystem;
  const path = yield* Path.Path;
  const links = antigravityUserSkillDirectories(path, input.profileDirectory);
  const targets = antigravityUserSkillDirectories(path, path.join(input.userHome, ".gemini"));
  for (const [link, target] of [
    [links[0], targets[0]],
    [links[1], targets[1]],
  ] as const) {
    yield* Effect.gen(function* () {
      // The harness creates these folders itself, and mkdir fails on a dangling link.
      if (!(yield* fs.exists(target))) {
        const linked = yield* fs.readLink(link).pipe(
          Effect.as(true),
          Effect.orElseSucceed(() => false),
        );
        if (linked) yield* fs.remove(link);
        return;
      }
      const existing = yield* fs.readLink(link).pipe(
        Effect.map((value): string | undefined => path.resolve(path.dirname(link), value)),
        Effect.catchReason("PlatformError", "NotFound", () => Effect.undefined),
        // An empty folder is the harness's placeholder from a launch without the link.
        // rmdir refuses a non-empty folder, so content added meanwhile is never deleted.
        Effect.catch((error) =>
          Effect.tryPromise(() => NodeFSP.rmdir(link)).pipe(
            Effect.as(undefined),
            Effect.mapError(() => error),
          ),
        ),
      );
      if (existing === target) return;
      if (existing !== undefined) {
        yield* fs.remove(link);
      }
      yield* fs.makeDirectory(path.dirname(link), { recursive: true });
      yield* Effect.tryPromise(() =>
        NodeFSP.symlink(target, link, input.platform === "win32" ? "junction" : "dir"),
      );
    }).pipe(
      Effect.catch((error) =>
        Effect.logWarning("Antigravity user skills are not linked into the profile.", {
          link,
          target,
          error,
        }),
      ),
    );
  }
});

export const prepareAntigravityProfile = Effect.fn("prepareAntigravityProfile")(function* (input: {
  readonly profileDirectory: string;
  readonly baseEnv?: NodeJS.ProcessEnv;
  readonly runtimeExecutablePath?: string;
  readonly platform?: NodeJS.Platform;
  readonly auth?: AntigravityAuthConfig;
  readonly userHome?: string;
  readonly tempDirectory?: string;
}) {
  const auth = input.auth ?? ANTIGRAVITY_PERSONAL_AUTH;
  const fs = yield* FileSystem.FileSystem;
  const path = yield* Path.Path;
  const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
  const platform = input.platform ?? (yield* HostProcess.Platform);
  const userHome =
    input.userHome ??
    resolveAntigravityUserHome(
      platform,
      input.baseEnv ?? process.env,
      yield* HostProcess.HomeDirectory,
    );
  const runtimeExecutablePath =
    input.runtimeExecutablePath ??
    (yield* resolveNodeExecutable("Antigravity sign-in", input.baseEnv).pipe(
      Effect.mapError(
        (cause) =>
          new AcpErrors.AcpTransportError({
            detail: nodeRuntimeUnavailableMessage("Antigravity sign-in"),
            cause,
          }),
      ),
    ));
  const helperExecutable =
    platform === "win32" ? runtimeExecutablePath.replaceAll("\\", "/") : runtimeExecutablePath;
  const browserArguments = [helperExecutable, "-e", browserHelperSource, "--", "%s"];
  const browserCommand = browserArguments.map(quoteBrowserArgument).join(" ");
  if (
    browserCommand.includes(platform === "win32" ? ";" : ":") ||
    helperExecutable.includes("\r") ||
    helperExecutable.includes("\n") ||
    helperExecutable.includes("\0") ||
    helperExecutable.includes("%s")
  ) {
    return yield* authSupportError(
      "The T3 runtime path cannot be used to suppress Antigravity browser launches.",
    );
  }

  const geminiHome = path.resolve(input.profileDirectory);
  const acpDirectory = path.join(geminiHome, "antigravity-acp");
  const tempDirectory = input.tempDirectory ?? path.join(acpDirectory, "tmp");
  let caBundlePath: string | undefined;
  if (platform === "linux") {
    // Bundled Python may look for certificates at paths absent on this distribution.
    // Relative paths would resolve differently when the agent runs in the project directory.
    for (const candidate of [
      (input.baseEnv ?? process.env).NIX_SSL_CERT_FILE,
      "/etc/ssl/certs/ca-bundle.crt",
      "/etc/ssl/certs/ca-certificates.crt",
      "/etc/pki/tls/certs/ca-bundle.crt",
      "/etc/ssl/cert.pem",
    ]) {
      if (
        candidate &&
        path.isAbsolute(candidate) &&
        (yield* fs.exists(candidate).pipe(Effect.orElseSucceed(() => false)))
      ) {
        caBundlePath = candidate;
        break;
      }
    }
  }
  const profile: AntigravityProfile = {
    platform,
    geminiHome,
    acpDirectory,
    tokenPath: path.join(acpDirectory, "acp_token.json"),
    tempDirectory,
    browserCommand,
    ...(caBundlePath === undefined ? {} : { caBundlePath }),
  };
  const environment = antigravityEnvironment(profile, input.baseEnv ?? process.env, auth);
  yield* Effect.gen(function* () {
    const child = yield* spawner.spawn(
      ChildProcess.make(helperExecutable, ["-e", browserHelperSource, "--", browserPreflightUrl], {
        env: environment,
        extendEnv: false,
        shell: false,
      }),
    );
    const [stdout, stderr, exitCode] = yield* Effect.all(
      [
        collectUint8StreamText({ stream: child.stdout, maxBytes: 4_096 }),
        collectUint8StreamText({ stream: child.stderr, maxBytes: 4_096 }),
        child.exitCode,
      ],
      { concurrency: "unbounded" },
    );
    if (
      Number(exitCode) !== 0 ||
      stdout.bytes !== 0 ||
      stdout.truncated ||
      stderr.truncated ||
      stderr.text !== `${ANTIGRAVITY_AUTH_BROWSER_MARKER}"${browserPreflightUrl}"\n`
    ) {
      return yield* authSupportError("Antigravity browser suppression could not be verified.");
    }
  }).pipe(
    Effect.scoped,
    Effect.timeoutOrElse({
      duration: "5 seconds",
      orElse: () =>
        Effect.fail(authSupportError("Antigravity browser suppression verification timed out.")),
    }),
    Effect.mapError((error) =>
      error._tag === "AcpTransportError"
        ? error
        : authSupportError("Antigravity browser suppression could not be verified."),
    ),
  );

  for (const directory of [geminiHome, acpDirectory, tempDirectory]) {
    yield* fs
      .makeDirectory(directory, { recursive: true, mode: 0o700 })
      .pipe(
        Effect.mapError(() =>
          authSupportError("The Antigravity profile directory could not be created."),
        ),
      );
    if (platform !== "win32") {
      yield* fs
        .chmod(directory, 0o700)
        .pipe(
          Effect.mapError(() =>
            authSupportError("The Antigravity profile directory permissions could not be set."),
          ),
        );
    }
  }
  yield* fs
    .writeFileString(path.join(acpDirectory, "settings.json"), antigravityProfileSettings(auth))
    .pipe(
      Effect.mapError(() =>
        authSupportError("The Antigravity profile settings could not be written."),
      ),
    );
  yield* linkAntigravityUserSkills({ profileDirectory: geminiHome, userHome, platform });
  return profile;
});

export function buildAntigravityAcpSpawnInput(input: {
  readonly installation: {
    readonly executablePath: string;
    readonly harnessPath: string;
  };
  readonly profile: AntigravityProfile;
  readonly cwd: string;
  readonly baseEnv?: NodeJS.ProcessEnv;
  readonly auth?: AntigravityAuthConfig;
  readonly runtimeTempDirectory?: string;
}): AcpSessionRuntime.AcpSpawnInput {
  return {
    command: input.installation.executablePath,
    args: input.profile.platform === "linux" ? ["--uid="] : [],
    cwd: input.cwd,
    env: {
      ...antigravityEnvironment(
        input.profile,
        input.baseEnv ?? process.env,
        input.auth ?? ANTIGRAVITY_PERSONAL_AUTH,
        input.runtimeTempDirectory,
      ),
      ANTIGRAVITY_HARNESS_PATH: input.installation.harnessPath,
    },
    extendEnv: false,
  };
}

export const parseAntigravityAuthorizationUrl = Effect.fn("parseAntigravityAuthorizationUrl")(
  function* (
    authorizationUrl: string,
  ): Effect.fn.Return<AntigravityAuthorizationUrl, AcpErrors.AcpError> {
    const invalidUrl = () =>
      authSupportError("Antigravity returned an invalid Google sign-in URL.");
    if (authorizationUrl.length > maxAuthorizationUrlLength || /\s/.test(authorizationUrl)) {
      return yield* invalidUrl();
    }
    const url = yield* decodeUrl(authorizationUrl).pipe(Effect.mapError(invalidUrl));
    const state = url.searchParams.get("state");
    const redirectUri = url.searchParams.get("redirect_uri");
    if (
      url.origin !== "https://accounts.google.com" ||
      url.pathname !== "/o/oauth2/v2/auth" ||
      url.username !== "" ||
      url.password !== "" ||
      url.hash !== "" ||
      url.searchParams.getAll("state").length !== 1 ||
      url.searchParams.getAll("redirect_uri").length !== 1 ||
      url.searchParams.getAll("response_type").length !== 1 ||
      url.searchParams.get("response_type") !== "code" ||
      state === null ||
      state.length === 0 ||
      state.length > 512 ||
      /\s/.test(state) ||
      redirectUri === null ||
      !/^http:\/\/127\.0\.0\.1:[1-9][0-9]{0,4}\/$/.test(redirectUri)
    ) {
      return yield* invalidUrl();
    }
    const redirect = yield* decodeUrl(redirectUri).pipe(Effect.mapError(invalidUrl));
    if (Number(redirect.port) < 1_024) return yield* invalidUrl();
    return { authorizationUrl, redirectUri, state };
  },
);

export function makeAntigravityStdoutTransform(
  input: {
    readonly onAuthorizationUrl?: (
      authorizationUrl: string,
    ) => Effect.Effect<void, AcpErrors.AcpError>;
  } = {},
) {
  const handleLine = Effect.fn("antigravityAuthSupport.handleStdoutLine")(function* (
    line: Uint8Array,
  ) {
    if (!authPrefixBytes.every((byte, index) => line[index] === byte)) return [line];
    const message = new TextDecoder().decode(line).replace(/\r?\n$/, "");
    const request = yield* parseAntigravityAuthorizationUrl(
      message.slice(ANTIGRAVITY_AUTH_STDOUT_PREFIX.length),
    );
    if (!input.onAuthorizationUrl) {
      return yield* authSupportError(ANTIGRAVITY_SIGN_IN_REQUIRED_MESSAGE);
    }
    yield* input.onAuthorizationUrl(request.authorizationUrl);
    return [];
  });

  return (
    stdout: ChildProcessSpawner.ChildProcessHandle["stdout"],
  ): Stream.Stream<Uint8Array, PlatformError.PlatformError | AcpErrors.AcpError> =>
    Stream.suspend(() => {
      let pending: Uint8Array[] = [];
      let pendingBytes = 0;
      const finishLine = () => {
        const line = Buffer.concat(pending, pendingBytes);
        pending = [];
        pendingBytes = 0;
        return line;
      };
      return stdout.pipe(
        Stream.mapEffect(
          Effect.fn("antigravityAuthSupport.splitStdoutLines")(function* (chunk: Uint8Array) {
            const lines: Uint8Array[] = [];
            let offset = 0;
            while (offset < chunk.byteLength) {
              const newline = chunk.indexOf(10, offset);
              const end = newline === -1 ? chunk.byteLength : newline + 1;
              const part = chunk.subarray(offset, end);
              if (pendingBytes + part.byteLength > maxStdoutLineBytes) {
                return yield* authSupportError(
                  "Antigravity sent a protocol line that is too large.",
                );
              }
              pending.push(part);
              pendingBytes += part.byteLength;
              if (newline !== -1) lines.push(finishLine());
              offset = end;
            }
            return lines;
          }),
        ),
        Stream.flatMap(Stream.fromIterable),
        Stream.concat(
          Stream.suspend(() => (pendingBytes > 0 ? Stream.succeed(finishLine()) : Stream.empty)),
        ),
        Stream.mapEffect(handleLine),
        Stream.flatMap(Stream.fromIterable),
      );
    });
}

export function makeAntigravityStderrHandler(
  input: {
    readonly onAuthorizationUrl?: (
      authorizationUrl: string,
    ) => Effect.Effect<void, AcpErrors.AcpError>;
  } = {},
) {
  let pending = "";
  const handleLine = (line: string) => {
    const message = line.endsWith("\r") ? line.slice(0, -1) : line;
    if (message.length > maxBrowserHelperLineLength) {
      return Effect.void;
    }
    const url = message.startsWith(ANTIGRAVITY_AUTH_STDOUT_PREFIX)
      ? Effect.succeed(message.slice(ANTIGRAVITY_AUTH_STDOUT_PREFIX.length))
      : message.startsWith(ANTIGRAVITY_AUTH_BROWSER_MARKER)
        ? decodeBrowserHelperUrl(message.slice(ANTIGRAVITY_AUTH_BROWSER_MARKER.length))
        : undefined;
    if (url === undefined) return Effect.void;
    return url.pipe(
      Effect.flatMap(parseAntigravityAuthorizationUrl),
      Effect.matchEffect({
        onFailure: () => Effect.void,
        onSuccess: (request) =>
          input.onAuthorizationUrl
            ? input.onAuthorizationUrl(request.authorizationUrl)
            : Effect.fail(authSupportError(ANTIGRAVITY_SIGN_IN_REQUIRED_MESSAGE)),
      }),
    );
  };

  return Effect.fn("antigravityAuthSupport.handleStderr")(function* (text: string) {
    const lines = `${pending}${text}`.split("\n");
    pending = lines.pop() ?? "";
    if (pending.length > maxBrowserHelperLineLength) pending = "";
    yield* Effect.forEach(lines, handleLine, { discard: true });
  });
}