import path from "node:path";
import type { WorkspaceRegistryConfig } from "./workspaces/types.js";

export interface AppConfig {
  host: string; port: number; harnessDir: string; thtBin: string; piBin: string;
  authMode: "none" | "mock" | "upstream";
  sessionStorage: {
    mode: "local" | "postgres";
    host?: string; port?: number; database?: string; runtimeUser?: string;
    runtimePasswordFile?: string; sslmode?: "verify-ca" | "verify-full"; sslrootcert?: string;
  };
  defaults: { provider?: string; model?: string; thinking?: string };
  maxPiProcesses: number;
  settingsFile: string;
  dataRoot?: string;
  ollamaEnsureTimeoutMs: number;
  secretsFile?: string;
  secretFiles: Readonly<Record<string, string | undefined>>;
  modelApiKeyFile?: string;
  /**
   * Local-only: when true, POST /sessions probes DWH reachability (`tht db ping`) and
   * refuses to create a session if it is down. Off by default so containers/CI never
   * pay the probe; the local dev launcher (run-stack.sh) opts in via THT_DWH_PRECHECK.
   */
  dwhPrecheck: boolean;
  workspaceRegistry: WorkspaceRegistryConfig;
}

function requiredRegistryValue(value: string, label: string): string {
  if (value.length === 0 || value.trim() !== value || value.includes("\0")) {
    throw new Error(`workspace registry ${label} configuration is invalid`);
  }
  return value;
}

function absoluteRegistryPath(value: string, label: string): string {
  const pathValue = requiredRegistryValue(value, label);
  if (!path.isAbsolute(pathValue)) {
    throw new Error(`workspace registry ${label} must be absolute`);
  }
  return pathValue;
}

function positiveImportLimit(value: string | undefined, fallback: number): number {
  const limit = Number(value ?? fallback);
  if (!Number.isSafeInteger(limit) || limit <= 0) {
    throw new Error("workspace import limit configuration is invalid");
  }
  return limit;
}

export function loadConfig(env: Record<string, string | undefined>): AppConfig {
  const authMode = env.AUTH_MODE ?? "none";
  if (!(["none", "mock", "upstream"] as const).includes(authMode as AppConfig["authMode"])) {
    throw new Error(`unsupported AUTH_MODE=${authMode}; use none, mock, or upstream`);
  }
  if (env.THOTH_PUBLIC_EXPOSURE === "true" && authMode !== "upstream") {
    throw new Error("public exposure requires AUTH_MODE=upstream behind a trusted proxy");
  }
  const sessionStorageMode = env.THT_SESSION_STORAGE ?? "local";
  if (sessionStorageMode !== "local" && sessionStorageMode !== "postgres") {
    throw new Error("session storage configuration is invalid");
  }
  if (sessionStorageMode === "local" && env.THOTH_PUBLIC_EXPOSURE === "true") {
    throw new Error("local session storage requires loopback-only deployment");
  }
  const sessionStorage: AppConfig["sessionStorage"] = { mode: sessionStorageMode };
  if (sessionStorageMode === "postgres") {
    const host = env.THT_SESSION_DB_HOST;
    const database = env.THT_SESSION_DB_NAME;
    const runtimeUser = env.THT_SESSION_RUNTIME_USER;
    const runtimePasswordFile = env.THT_SESSION_RUNTIME_PASSWORD_FILE;
    const sslmode = env.THT_SESSION_DB_SSLMODE;
    const sslrootcert = env.THT_SESSION_DB_SSLROOTCERT;
    const port = Number(env.THT_SESSION_DB_PORT ?? 5432);
    if (
      authMode !== "upstream"
      || !host || !database || !runtimeUser
      || !runtimePasswordFile || !path.isAbsolute(runtimePasswordFile)
      || (sslmode !== "verify-ca" && sslmode !== "verify-full")
      || !sslrootcert || !path.isAbsolute(sslrootcert)
      || !Number.isInteger(port) || port < 1 || port > 65535
    ) {
      if (authMode !== "upstream") {
        throw new Error("server session storage requires AUTH_MODE=upstream");
      }
      throw new Error("server session storage configuration is invalid");
    }
    sessionStorage.host = host;
    sessionStorage.port = port;
    sessionStorage.database = database;
    sessionStorage.runtimeUser = runtimeUser;
    sessionStorage.runtimePasswordFile = runtimePasswordFile;
    sessionStorage.sslmode = sslmode;
    sessionStorage.sslrootcert = sslrootcert;
  }
  const modelApiKeyFile = env.THT_MODEL_API_KEY_FILE;
  if (modelApiKeyFile !== undefined && (
    modelApiKeyFile.trim() !== modelApiKeyFile
    || modelApiKeyFile.length === 0
    || modelApiKeyFile.includes("\0")
    || !path.isAbsolute(modelApiKeyFile)
  )) {
    throw new Error("model credential configuration is invalid");
  }
  const secretsFile = env.THT_SECRETS_FILE;
  if (secretsFile !== undefined && (
    secretsFile.trim() !== secretsFile || secretsFile.length === 0 || secretsFile.includes("\0")
    || !path.isAbsolute(secretsFile)
  )) throw new Error("secret bundle configuration is invalid");
  const secretFiles: Record<string, string | undefined> = {};
  for (const name of [
    "THT_MODEL_API_KEY_SECRET_FILE", "THT_DWH_API_KEY_SECRET_FILE", "THT_VEC_API_KEY_SECRET_FILE",
    "THT_VEC_WRITE_API_KEY_SECRET_FILE", "THT_CA_SECRET_FILE", "THT_VECTOR_BOOTSTRAP_PASSWORD_SECRET_FILE",
    "THT_VECTOR_MIGRATOR_PASSWORD_SECRET_FILE", "THT_VECTOR_READER_PASSWORD_SECRET_FILE",
    "THT_VECTOR_WRITER_PASSWORD_SECRET_FILE",
  ]) secretFiles[name] = env[name];
  const registryRoot = absoluteRegistryPath(
    env.THT_WORKSPACE_REGISTRY_ROOT ?? "/data/workspace-registry",
    "root",
  );
  const registryBranch = requiredRegistryValue(env.THT_WORKSPACE_GIT_BRANCH ?? "main", "branch");
  const installationId = requiredRegistryValue(
    env.THT_WORKSPACE_INSTALLATION_ID ?? "local",
    "installation ID",
  );
  const remoteUrl = env.THT_WORKSPACE_GIT_REMOTE === undefined
    ? undefined
    : requiredRegistryValue(env.THT_WORKSPACE_GIT_REMOTE, "remote");
  const secretRoots = (env.THT_WORKSPACE_SECRET_ROOTS ?? "")
    .split(",")
    .filter((root) => root.length > 0)
    .map((root) => absoluteRegistryPath(root, "secret root"));
  const workspaceRegistry: WorkspaceRegistryConfig = {
    root: registryRoot,
    remoteUrl,
    branch: registryBranch,
    gitAuthorName: requiredRegistryValue(
      env.THT_WORKSPACE_GIT_AUTHOR_NAME ?? "Thoth Workspace Registry",
      "Git author name",
    ),
    gitAuthorEmail: requiredRegistryValue(
      env.THT_WORKSPACE_GIT_AUTHOR_EMAIL ?? "thoth-workspace-registry@localhost",
      "Git author email",
    ),
    installationId,
    secretRoots,
    maxImportBytes: positiveImportLimit(env.THT_WORKSPACE_MAX_IMPORT_BYTES, 10 * 1024 * 1024),
    maxImportEntries: positiveImportLimit(env.THT_WORKSPACE_MAX_IMPORT_ENTRIES, 32),
  };
  return {
    host: env.HOST ?? "127.0.0.1",
    port: Number(env.PORT ?? 8787),
    harnessDir: env.THT_HARNESS_DIR ?? "../harness",
    thtBin: env.THT_BIN ?? "tht",
    piBin: env.PI_BIN ?? "pi",
    authMode: authMode as AppConfig["authMode"],
    sessionStorage,
    defaults: { provider: env.PI_PROVIDER, model: env.PI_MODEL, thinking: env.PI_THINKING },
    maxPiProcesses: Number(env.MAX_PI_PROCESSES ?? 4),
    settingsFile: env.SETTINGS_FILE ?? "data/settings.json",
    dataRoot: env.THT_DATA_ROOT,
    ollamaEnsureTimeoutMs: Number(env.OLLAMA_ENSURE_TIMEOUT_MS ?? 60000),
    secretsFile,
    secretFiles,
    modelApiKeyFile,
    dwhPrecheck: env.THT_DWH_PRECHECK === "true" || env.THT_DWH_PRECHECK === "1",
    workspaceRegistry,
  };
}