/**
 * Server-side configuration, read from the environment on every request so
 * that editing `.env.local` only requires a dev-server restart.
 *
 * Never import this into a client component: it would leak the API key.
 */

import { sanitiseApiKey } from "./http-guard";
import { translate, type Locale } from "./i18n-dict";
import path from "node:path";

export type AuthMode = "user-key" | "server" | "local";

export type ServerConfig = {
  baseUrl: string;
  apiKey: string;
  authMode: AuthMode;
  visionModel: string;
  textModel: string;
  /** True when talking straight to https://ollama.com (needs an API key). */
  directCloud: boolean;
  timeoutMs: number;
  healthTimeoutMs: number;
  /** `false` sends `think: false`; `null` omits the field entirely. */
  think: boolean | null;
  defaultActivityCount: number;
  rateLimits: {
    windowMs: number;
    generate: number;
    grade: number;
    homework: number;
    health: number;
    sync: number;
  };
  sync: {
    /** Where opaque encrypted sync blobs live (SYNC_DIR). */
    dir: string;
    /** Per-blob cap in bytes (SYNC_MAX_BYTES). */
    maxBytes: number;
    /** Total cap for the whole directory in bytes (SYNC_TOTAL_BYTES). */
    totalBytes: number;
  };
};

/** What a single request should use to talk to Ollama. */
export type OllamaAuth = {
  baseUrl: string;
  apiKey: string;
  directCloud: boolean;
  authMode: AuthMode;
};

function positiveInt(value: string | undefined, fallback: number): number {
  const parsed = Number.parseInt(value ?? "", 10);
  return Number.isFinite(parsed) && parsed > 0 ? parsed : fallback;
}

function trimTrailingSlash(url: string): string {
  return url.replace(/\/+$/, "");
}

export function getServerConfig(): ServerConfig {
  const baseUrl = trimTrailingSlash(
    process.env.OLLAMA_BASE_URL?.trim() || "http://localhost:11434",
  );
  const apiKey = process.env.OLLAMA_API_KEY?.trim() || "";

  const rawAuthMode = process.env.OLLAMA_AUTH?.trim().toLowerCase();
  const authMode: AuthMode =
    rawAuthMode === "local" || rawAuthMode === "server" || rawAuthMode === "user-key"
      ? rawAuthMode
      : rawAuthMode === "none"
        ? "local"
        : "user-key";

  let directCloud = false;
  try {
    const host = new URL(baseUrl).hostname.toLowerCase();
    directCloud = host === "ollama.com" || host.endsWith(".ollama.com");
  } catch {
    directCloud = false;
  }

  const thinkRaw = process.env.OLLAMA_THINK?.trim().toLowerCase();
  const think =
    thinkRaw === "false" ? false : thinkRaw === "true" ? true : null;

  const count = Number.parseInt(
    process.env.FREEZMO_DEFAULT_ACTIVITY_COUNT ?? "",
    10,
  );

  return {
    baseUrl,
    apiKey,
    authMode,
    visionModel: process.env.VISION_MODEL?.trim() || "gemma4:31b-cloud",
    textModel: process.env.TEXT_MODEL?.trim() || "gpt-oss:120b-cloud",
    directCloud,
    timeoutMs: Number.parseInt(process.env.OLLAMA_TIMEOUT_MS ?? "", 10) || 300_000,
    healthTimeoutMs:
      Number.parseInt(process.env.OLLAMA_HEALTH_TIMEOUT_MS ?? "", 10) || 8_000,
    think,
    defaultActivityCount: Number.isFinite(count) ? Math.min(Math.max(count, 6), 20) : 10,
    rateLimits: {
      windowMs: positiveInt(process.env.RATE_LIMIT_WINDOW_MS, 300_000),
      generate: positiveInt(process.env.RATE_LIMIT_GENERATE, 12),
      grade: positiveInt(process.env.RATE_LIMIT_GRADE, 40),
      // Homework is one to two model calls, like a deck.
      homework: positiveInt(process.env.RATE_LIMIT_HOMEWORK, 12),
      health: positiveInt(process.env.RATE_LIMIT_HEALTH, 90),
      // Sync is cheap (no model calls) but shouldn't be hammered.
      sync: positiveInt(process.env.RATE_LIMIT_SYNC, 60),
    },
    sync: {
      dir: process.env.SYNC_DIR?.trim() || path.join(process.cwd(), ".freezmo", "sync"),
      maxBytes: positiveInt(process.env.SYNC_MAX_BYTES, 12 * 1024 * 1024),
      totalBytes: positiveInt(process.env.SYNC_TOTAL_BYTES, 1024 * 1024 * 1024),
    },
  };
}

/**
 * Human-readable explanation for every auth configuration problem, so the UI
 * never has to show a bare "unauthorised".
 */
const AUTH_ERROR_KEYS: Record<"missing_key" | "server_key_missing" | "local_with_cloud_url", string> = {
  missing_key: "server.authMissingKey",
  server_key_missing: "server.authServerKeyMissing",
  local_with_cloud_url: "server.authLocalCloud",
};

export function authErrorMessage(locale: Locale, error: keyof typeof AUTH_ERROR_KEYS): string {
  return translate(locale, AUTH_ERROR_KEYS[error]);
}

export function authErrorKind(error: "missing_key" | "server_key_missing" | "local_with_cloud_url"): string {
  if (error === "missing_key") return "needs_key";
  return "config";
}

/** Header a browser uses to hand over its own key for a single request. */
export const API_KEY_HEADER = "x-ollama-key";



/**
 * Works out which credentials a request may use.
 *
 *  - `user-key` (default): the key must come from the browser. Nothing is
 *    stored server-side, ever — it is used for this request and dropped.
 *  - `server`: the key comes from `.env.local` (single-user installs).
 *  - `local`: neither; a local daemon signed in with `ollama signin`.
 */
export function resolveAuth(
  config: ServerConfig,
  request: Request,
): { auth: OllamaAuth } | { error: "missing_key" | "server_key_missing" | "local_with_cloud_url" } {
  const headerKey = sanitiseApiKey(request.headers.get(API_KEY_HEADER));

  if (config.authMode === "local") {
    // A daemon without sign-in can't talk to the cloud API: catch the
    // misconfiguration here instead of returning a confusing 401 later.
    if (config.directCloud) return { error: "local_with_cloud_url" };
    return {
      auth: { baseUrl: config.baseUrl, apiKey: "", directCloud: config.directCloud, authMode: "local" },
    };
  }

  if (config.authMode === "server") {
    if (!config.apiKey) return { error: "server_key_missing" };
    return {
      auth: { baseUrl: config.baseUrl, apiKey: config.apiKey, directCloud: config.directCloud, authMode: "server" },
    };
  }

  if (!headerKey) return { error: "missing_key" };
  return {
    auth: { baseUrl: config.baseUrl, apiKey: headerKey, directCloud: config.directCloud, authMode: "user-key" },
  };
}

/**
 * Cloud models are addressed as `<model>:cloud` (or `<model>-cloud`) by a
 * local daemon, but the direct cloud API uses the plain library name
 * (`gemma4:31b-cloud` -> `gemma4:31b`, `glm-5.3-flash:cloud` -> `glm-5.3-flash`).
 * Normalise so the same .env works in both modes.
 */
export function resolveModelName(model: string, directCloud: boolean): string {
  if (!directCloud) return model;
  if (model.endsWith(":cloud")) return model.slice(0, -":cloud".length);
  if (model.endsWith("-cloud")) return model.slice(0, -"-cloud".length);
  return model;
}

/** Strip local/daemon routing suffixes so model names can be compared. */
export function canonicalModelName(model: string): string {
  return model
    .replace(/:cloud$/, "")
    .replace(/-cloud$/, "")
    .toLowerCase();
}