/*
This file is based on the open source project https://google.github.io/sqlcommenter/
*/

import { Version } from "../conf/version";
import reqtrack from "./index";
import { traceParent } from "./tracecontext";

/* eslint-disable @typescript-eslint/no-unused-vars */

const routeKey = "route";
const controllerKey = "controller";
const actionKey = "action";
const frameworkKey = "framework";
const driverKey = "driver";
const traceparentKey = "traceparent";
const tracestateKey = "tracestate";
const applicationKey = "application";

/* eslint-enable @typescript-eslint/no-unused-vars */

/**
 * Adds a tracing comment to a query, which can then be used to trace the query
 * by the sidecar, and if supported by the database server, traced by the
 * database server too.
 *
 * (CloudSQL supports this, but not sure about other databases)
 */
export function queryWithComment(query: string, driver?: string): string {
  const ctx = reqtrack.current();
  if (ctx === undefined) {
    // If we're not tracking the request, return the query unmodified
    return query;
  }

  const tags: Record<string, string> = {
    [frameworkKey]: `encore/js/${Version}`,
    [traceparentKey]: traceParent(ctx.traceID, ctx.spanID),
  };
  if (driver !== undefined) {
    tags[driverKey] = driver;
  }

  const comment = `/*${convertMapToComment(tags)}*/`;

  // A semicolon at the end of the SQL statement means the query ends there.
  // We need to insert the comment before that to be considered as part of the SQL statemtent.
  const semicolonIndex = query.lastIndexOf(";");
  if (semicolonIndex !== -1) {
    // Check there's only whitespace after the semicolon
    const whitespace = query.substring(semicolonIndex + 1);
    if (!/^\s*$/.test(whitespace)) {
      return query + comment;
    }

    return (
      query.substring(0, semicolonIndex) +
      comment +
      query.substring(semicolonIndex)
    );
  } else {
    return query + comment;
  }
}

/**
 * ConvertMapToComment returns a comment string given a map of key-value pairs of tags.
 *
 * There are few steps involved here:
 *  - Sorting the tags by key string
 *  - url encoding the key value pairs
 *  - Formatting the key value pairs as "key1=value1,key2=value2" format.
 */
function convertMapToComment(tags: Record<string, string>): string {
  const keys = Object.keys(tags).sort();
  const pairs = keys.map(
    (key) =>
      `${encodeURIComponent(key)}='${encodeURIComponent(tags[key]).replace(
        "'",
        "\\'",
      )}'`,
  );
  return pairs.join(",");
}