import LogLevel from "./levels";
import { FieldsObject } from "./logger";
import { getStackTrace } from "./stack";

/**
 * A log hook is a function which is called with the log object, the log level, and the message
 * just before the log is written to the output.
 *
 * The logObject is the full JSON object which will be emitted, however for convenience the
 * level and message are also passed in.
 *
 * A hook is allowed to modify the log object as required.
 */
export type LogHook = (
  logObject: FieldsObject,
  level: LogLevel,
  msg: string,
) => void;

export function WithCaller(dropFrames = 0): LogHook {
  const encoreDevPkgDir = encorePackagesPath();

  return (logObject: FieldsObject) => {
    for (const frame of getStackTrace(dropFrames + 1)) {
      if (frame.file.startsWith(encoreDevPkgDir)) {
        continue;
      } else if (
        frame.file.indexOf("/.encore/build/") !== -1 ||
        frame.file.indexOf("/gen_encore.app/") !== -1
      ) {
        // Ignore generated code
        continue;
      }

      logObject.caller = `${frame.file}:${frame.line}`;
      break;
    }
  };
}

/**
 * Returns the path to the @encore.dev folder (or "packages" folder if running within the workspace)
 */
function encorePackagesPath(): string {
  const trace = getStackTrace();
  if (trace.length === 0) {
    throw new Error("unable to determine log package");
  }

  const components = trace[0].file.split("/");
  const fileName = components.pop()!;
  const last = () => components[components.length - 1];

  // Get the directory
  if (last() !== "internal") {
    // If we're compiled bundled output, the file extension will be .mjs or .js
    // so let's just return the path to the bundle
    if (fileName.endsWith(".mjs") || fileName.endsWith(".js")) {
      components.pop();
      return components.join("/") + "/";
    }
    throw new Error("unable to determine log package");
  }

  // Drop the "internal" folder
  components.pop();

  // Drop the "log" folder
  components.pop();

  // Drop the dist folder, if this is the compiled js output
  if (last() === "dist") {
    components.pop();
  }

  // Drop the "internal-runtime" folder.
  if (last() === "internal-runtime") {
    components.pop();
  }

  const suffix = last();
  if (
    suffix !== "encore.dev" &&
    suffix !== "@encore.dev" &&
    suffix !== "packages"
  ) {
    throw new Error("unable to determine encore.dev folder path");
  }

  return components.join("/") + "/";
}