"use strict";

const fs = require("fs");
const { parseOsm } = require("./osm");
const {
  buildTrafficSignalFeatures,
  buildTrafficSignalsFromFeatures,
  validateTrafficSignalFeatures,
  validateTrafficSignalSourceReferences,
} = require("./traffic-signals");

const SCHEMA = "native-traffic-signals/v1";

function loadOrGenerate(file, osmText, stopLines, intersections) {
  if (fs.existsSync(file)) {
    const document = JSON.parse(fs.readFileSync(file, "utf8"));
    try {
      return validateDocument(document, osmText);
    } catch (error) {
      // OSM edits can invalidate the stable identities in a document that was
      // itself generated from OSM. User-authored documents must remain strict.
      if (document?.provenance === "generated:osm-controls" && isStaleSourceReferenceError(error)) {
        return generate(osmText, stopLines, intersections);
      }
      throw error;
    }
  }
  return generate(osmText, stopLines, intersections);
}

function isStaleSourceReferenceError(error) {
  return error instanceof Error && /^traffic signal feature \d+: (approach_id .* is not present on OSM control|control_id .* is not present in the current OSM)/.test(error.message);
}

function generate(osmText, stopLines, intersections) {
  const controls = parseOsm(osmText).trafficSignalControls;
  return { schema: SCHEMA, provenance: "generated:osm-controls", assemblies: buildTrafficSignalFeatures(stopLines, intersections, controls) };
}

function validateDocument(value, osmText) {
  if (value?.schema !== SCHEMA) throw new Error(`Expected ${SCHEMA} signal document`);
  const assemblies = validateTrafficSignalFeatures(value.assemblies);
  if (osmText) validateTrafficSignalSourceReferences(assemblies, parseOsm(osmText).trafficSignalControls);
  return { schema: SCHEMA, provenance: value.provenance || "native", assemblies };
}

function runtime(document) { return buildTrafficSignalsFromFeatures(document.assemblies); }

module.exports = { SCHEMA, generate, loadOrGenerate, validateDocument, runtime };