import { fetchWithAuth } from "./auth";
import { getPreferences } from "./preferences";
import type {
  DepseudonymizeResponse,
  EntityType,
  PlaceholderMapping,
  PseudonymizeResponse,
} from "./types";

function escapeRegExp(value: string): string {
  return value.replace(/[.*+?^${}()|[\]\\]/g, "\\$&");
}

export function normalizePseudonymizeResponse(
  response: PseudonymizeResponse,
): PseudonymizeResponse {
  const normalizedMapping: PlaceholderMapping = {};
  const strippedKeys = new Set<string>();

  for (const [key, entry] of Object.entries(response.mapping)) {
    const stripped = key.replace(/[<>]/g, "");
    normalizedMapping[`<${stripped}>`] = entry;
    strippedKeys.add(stripped);
  }

  let text = response.pseudonymized_text;
  const ordered = Array.from(strippedKeys).sort((a, b) => b.length - a.length);
  for (const stripped of ordered) {
    const bracketed = `<${stripped}>`;
    const bareRegex = new RegExp(
      `(?<![<\\w])${escapeRegExp(stripped)}(?![\\w>])`,
      "g",
    );
    text = text.replace(bareRegex, bracketed);
  }

  return {
    ...response,
    pseudonymized_text: text,
    mapping: normalizedMapping,
  };
}

export function localDepseudonymize(
  text: string,
  mapping: PlaceholderMapping,
): DepseudonymizeResponse {
  let result = text;
  let replacementsMade = 0;

  const entries = Object.entries(mapping)
    .map(([key, entry]) => ({
      stripped: key.replace(/[<>]/g, ""),
      entry,
    }))
    .sort((a, b) => b.stripped.length - a.stripped.length);

  for (const { stripped, entry } of entries) {
    const bracketed = `<${stripped}>`;
    const bracketedRegex = new RegExp(escapeRegExp(bracketed), "g");
    const bracketedMatches = result.match(bracketedRegex);
    if (bracketedMatches) {
      replacementsMade += bracketedMatches.length;
      result = result.replace(bracketedRegex, entry.original);
    }

    const bareRegex = new RegExp(`\\b${escapeRegExp(stripped)}\\b`, "g");
    const bareMatches = result.match(bareRegex);
    if (bareMatches) {
      replacementsMade += bareMatches.length;
      result = result.replace(bareRegex, entry.original);
    }
  }

  return { original_text: result, replacements_made: replacementsMade };
}

function apiUrl(path: string): string {
  return `${getPreferences().velumBaseUrl}${path}`;
}

async function parseJsonResponse<T>(response: Response): Promise<T> {
  const contentType = response.headers.get("content-type") ?? "";
  if (!response.ok) {
    const details = await response.text().catch(() => response.statusText);
    throw new Error(
      `Velum API request failed: ${response.status} ${response.statusText}: ${details}`,
    );
  }
  if (!contentType.includes("application/json")) {
    const details = await response.text().catch(() => "");
    throw new Error(
      `Velum API returned non-JSON response: ${details.slice(0, 200)}`,
    );
  }
  return (await response.json()) as T;
}

export async function getEntityTypes(): Promise<EntityType[]> {
  const response = await fetchWithAuth(apiUrl("/api/entity-types"));
  const payload = await parseJsonResponse<{ entity_types: EntityType[] }>(
    response,
  );
  return payload.entity_types;
}

export async function pseudonymize(
  text: string,
  mapping: PlaceholderMapping,
  entityTypes?: EntityType[],
): Promise<PseudonymizeResponse> {
  const response = await fetchWithAuth(apiUrl("/api/pseudonymize"), {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      text,
      mapping,
      entity_types:
        entityTypes && entityTypes.length > 0 ? entityTypes : undefined,
    }),
  });

  return parseJsonResponse<PseudonymizeResponse>(response);
}

export async function depseudonymize(
  text: string,
  mapping: PlaceholderMapping,
): Promise<DepseudonymizeResponse> {
  const response = await fetchWithAuth(apiUrl("/api/depseudonymize"), {
    method: "POST",
    headers: {
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      text,
      mapping,
    }),
  });

  return parseJsonResponse<DepseudonymizeResponse>(response);
}