import { runtimePrivacyEnvironment } from "../shared/runtime-privacy-environment";
import { dirname, isAbsolute, join, relative, resolve, sep } from "node:path";
import {
  OPENCODE_REMOTE_RUNTIME_ENVIRONMENT_NAMES,
  remoteRuntimeBundleManifestSchema,
  type RemoteRuntimeBundleManifest,
} from "../shared/remote-runtime-launch-contracts";
import {
  modelBridgePolicySchema,
  type ModelBridgePolicy,
} from "../shared/model-bridge-contracts";
import { assertAbsoluteManagedPath } from "./managed-paths";

const OPEN_CODE_RUNTIME_ENVIRONMENT = Object.freeze({
  OPENCODE_DISABLE_AUTOUPDATE: "1",
  OPENCODE_DISABLE_CLAUDE_CODE_SKILLS: "1",
  OPENCODE_DISABLE_EMBEDDED_WEB_UI: "1",
  OPENCODE_DISABLE_EXTERNAL_SKILLS: "1",
  OPENCODE_EXPERIMENTAL_DISABLE_FILEWATCHER: "1",
  OPENCODE_DISABLE_LSP_DOWNLOAD: "1",
  OPENCODE_DISABLE_MODELS_FETCH: "1",
  OPENCODE_DISABLE_PROJECT_CONFIG: "1",
  OPENCODE_DISABLE_SHARE: "1",
});

export type OpenCodeLaunchProfile = {
  executable: string;
  processExecutable: string;
  args: readonly string[];
  cwd: string;
  env: Readonly<NodeJS.ProcessEnv>;
};

export function createOpenCodeLaunchProfile(input: {
  manifest: RemoteRuntimeBundleManifest;
  bundleDirectory: string;
  workspaceDirectory: string;
  modelBridge?: {
    agentExecutablePath: string;
    bridgeDirectory: string;
    socketPath: string;
    policy: ModelBridgePolicy;
    sharedSessions?: boolean;
  };
}): OpenCodeLaunchProfile {
  const manifest = remoteRuntimeBundleManifestSchema.parse(input.manifest);
  const isContinue = manifest.runtimeId === "continue" && manifest.provider === "continue";
  if (
    !isContinue && (manifest.runtimeId !== "opencode" ||
    manifest.provider !== "opencode" ||
    manifest.entrypoint.identity !== "opencode-acp" ||
    manifest.entrypoint.argvPrefix.length !== 1 ||
    manifest.entrypoint.argvPrefix[0] !== "acp")
  ) {
    throw new Error("Runtime manifest is not the fixed OpenCode ACP profile");
  }
  if (isContinue && (manifest.entrypoint.identity !== "continue-acp" ||
    manifest.entrypoint.path !== "lib/continue/dist/cn.js" || manifest.entrypoint.argvPrefix.length !== 0 || !input.modelBridge)) {
    throw new Error("Continue requires its managed ACP facade and model bridge");
  }
  if (
    [...manifest.allowedEnvironmentNames].sort().join("\0") !==
    [...OPENCODE_REMOTE_RUNTIME_ENVIRONMENT_NAMES].sort().join("\0")
  ) {
    throw new Error(
      "OpenCode Runtime environment allowlist does not match the fixed profile",
    );
  }

  const bundleDirectory = assertAbsoluteManagedPath(
    resolve(input.bundleDirectory),
  );
  const workspaceDirectory = normalizedAbsolutePath(
    input.workspaceDirectory,
    "Workspace",
  );
  const modelBridge =
    input.modelBridge === undefined
      ? undefined
      : {
          agentExecutablePath: normalizedAbsolutePath(
            input.modelBridge.agentExecutablePath,
            "Agent executable",
          ),
          agentInstallationDirectory: normalizedAbsolutePath(
            dirname(input.modelBridge.agentExecutablePath),
            "Agent installation",
          ),
          bridgeDirectory: normalizedAbsolutePath(
            input.modelBridge.bridgeDirectory,
            "Model bridge",
          ),
          socketPath: normalizedAbsolutePath(
            input.modelBridge.socketPath,
            "Model bridge socket",
          ),
          policy: modelBridgePolicySchema.parse(input.modelBridge.policy),
          sharedSessions: input.modelBridge.sharedSessions === true,
        };
  if (
    modelBridge !== undefined &&
    (!isStrictDescendant(modelBridge.bridgeDirectory, modelBridge.socketPath) ||
      !isStrictDescendant(
        modelBridge.agentInstallationDirectory,
        modelBridge.agentExecutablePath,
      ))
  ) {
    throw new Error(
      "Model bridge socket or Agent executable escapes its managed directory",
    );
  }
  const executablePath = resolve(
    bundleDirectory,
    ...manifest.entrypoint.path.split("/"),
  );
  if (!isStrictDescendant(bundleDirectory, executablePath)) {
    throw new Error("OpenCode entrypoint escapes its bundle directory");
  }

  const runtimeCommand =
    modelBridge === undefined
      ? {
          executable: executablePath,
          args: [...manifest.entrypoint.argvPrefix],
        }
      : {
          executable: join(modelBridge.agentInstallationDirectory, "node"),
          args: [
            join(modelBridge.agentInstallationDirectory, "lib", "agent.cjs"),
            "model-bridge-helper",
            "--socket-path",
            modelBridge.socketPath,
            "--protocol",
            modelBridge.policy.protocol,
            "--model",
            modelBridge.policy.model,
            "--supports-image-input",
            modelBridge.policy.supportsImageInput ? "true" : "false",
            ...(modelBridge.sharedSessions ? ["--shared-sessions", "true"] : []),
            ...(isContinue ? ["--runtime-id", "continue"] : []),
            isContinue ? "--continue-entrypoint" : "--opencode-entrypoint",
            executablePath,
          ],
        };

  const environmentBase = {
    ...executeEnvironment(process.env, workspaceDirectory),
    ...runtimePrivacyEnvironment,
    ...(isContinue ? {} : { ...OPEN_CODE_RUNTIME_ENVIRONMENT,
      OPENCODE_CONFIG_DIR: join(bundleDirectory, "config", "opencode") }),
  };
  const permission = "allow";
  const environment = {
    ...environmentBase,
    ...(isContinue ? {} : { OPENCODE_CONFIG_CONTENT: JSON.stringify({
      // Native snapshot summaries are not consumed by GoodBuddy.
      snapshot: false,
      permission,
      agent: { build: { permission } },
    }) }),
  };
  return {
    ...runtimeCommand,
    processExecutable: runtimeCommand.executable,
    cwd: workspaceDirectory,
    env: environment,
  };
}

function normalizedAbsolutePath(value: string, label: string): string {
  if (value.includes("\0") || !isAbsolute(value) || resolve(value) !== value) {
    throw new Error(`${label} path must be a normalized absolute path`);
  }
  return value;
}

function executeEnvironment(
  source: Readonly<NodeJS.ProcessEnv>,
  workspaceDirectory: string,
): Readonly<NodeJS.ProcessEnv> {
  const home = usableEnvironmentValue(source.HOME)
    ? source.HOME!
    : workspaceDirectory;
  const defaults = {
    HOME: home,
    LANG: "C.UTF-8",
    LC_ALL: "C.UTF-8",
    PATH: "/usr/bin:/bin",
    TMPDIR: "/tmp",
    XDG_CACHE_HOME: join(home, ".cache"),
    XDG_CONFIG_HOME: join(home, ".config"),
    XDG_DATA_HOME: join(home, ".local", "share"),
    XDG_STATE_HOME: join(home, ".local", "state"),
  } as const;
  const environment: NodeJS.ProcessEnv = { ...source };
  for (const [name, fallback] of Object.entries(defaults)) {
    if (!usableEnvironmentValue(environment[name])) {
      environment[name] = fallback;
    }
  }
  return environment;
}

function usableEnvironmentValue(value: string | undefined): value is string {
  return value !== undefined && value.length > 0 && !value.includes("\0");
}

function isStrictDescendant(parent: string, candidate: string): boolean {
  const child = relative(parent, candidate);
  return (
    child.length > 0 &&
    child !== ".." &&
    !child.startsWith(`..${sep}`) &&
    !isAbsolute(child)
  );
}