// Finds PIS Codes using DB Lookups

const db = require("../services/dbAccess.services");
const clean = require("../utils/sanitizer.utils");

import type { OB_Pis_SimpleObject } from "@owlboard/ts-types";

import { logger } from "../utils/logger.utils";
import { queryAggregate } from "./dbAccess.services";
import {
  getPartialEndTiplocMatchPipeline,
  getFullTiplocMatchPipeline,
} from "../utils/pis.utils";
import { Document } from "mongodb";

export const supported = ["GW", "UK"];

async function findPisByOrigDest(start: string, end: string) {
  logger.debug(
    `pisServices.findPisByOrigDest: Searching for Orig: ${start}, Dest: ${end}`
  );
  const firstCrs = clean.cleanApiEndpointTxt(start.toLowerCase());
  const lastCrs = clean.cleanApiEndpointTxt(end.toLowerCase());
  const query = {
    stops: {
      $all: [
        { $elemMatch: { $eq: firstCrs } },
        { $elemMatch: { $eq: lastCrs } },
      ],
    },
    $expr: {
      $and: [
        { $eq: [{ $arrayElemAt: ["$stops", -1] }, lastCrs] },
        { $eq: [{ $arrayElemAt: ["$stops", 0] }, firstCrs] },
      ],
    },
  };
  const search = await db.query("pis", query);
  // Check for results, if none then try partial match
  return search;
}

async function findPisByCode(
  code: string
): Promise<OB_Pis_SimpleObject | null> {
  logger.debug(`pisServices.findPisByCode: Searching for PIS code: ${code}`);
  const cleanCode = clean.removeNonNumeric(code);
  const query = {
    code: parseInt(cleanCode),
  };
  const search = db.query("pis", query);
  return await search;
}

// Queries the database for PIS codes that match the given TIPLOC array
export async function findByTiplocArray(
  tiplocArray: string[]
): Promise<OB_Pis_SimpleObject | null> {
  // Firstly fix errant TIPLOCS such as RDNG4AB which will never return a result
  // currently only works with RDNG4AB - checks for presence of RDNG4AB first to
  // avoid iterating over every array ever searched for.
  if (tiplocArray.includes("RDNG4AB")) {
    fixErrantTiplocs(tiplocArray);
  }

  // PERFORMANCE NOTE:
  //   The majority of queries will return a full match,
  //   this means that a more performant pipeline is used
  //   to find a full match and only then are more
  //   complicated pipelines used to find partial matches
  //   if the first pipeline returns nothing.
  try {
    const exactMatch = await findExactMatchByTiploc(tiplocArray);
    if (exactMatch) {
      return convertDocument(exactMatch, "none");
    } else {
      const partialEnd = await findPartialEndMatchByTiploc(tiplocArray);
      if (partialEnd) {
        return convertDocument(partialEnd, "first");
      } else {
        // Here, I should search for a partialStart match.  For now return null.
        return null;
      }
    }
  } catch (err) {
    logger.error(err, "Error in findByTiplocArray");
    return null;
  }
}

// Uses a pipeline to find an exact match
async function findExactMatchByTiploc(array: string[]): Promise<Document> {
  const pipeline = getFullTiplocMatchPipeline(array);
  const res = await queryAggregate("pis", pipeline);
  return res[0];
}

// Uses a pipeline to find a partial match - only supporting
// codes ending with the correct stops for now.
async function findPartialEndMatchByTiploc(array: string[]): Promise<Document> {
  const pipeline = getPartialEndTiplocMatchPipeline(array);
  const res = await queryAggregate("pis", pipeline);
  return res[0];
}

function convertDocument(doc: Document, skipType: string): OB_Pis_SimpleObject {
  return {
    code: doc.code.toString(),
    toc: doc.toc,
    skipCount: doc.skipStops,
    skipType: skipType,
  };
}

// Changes any instance of 'RDNG4AB' to 'RDNGSTN'
function fixErrantTiplocs(input: string[]): void {
  input.forEach((value, index, array) => {
    if (value === "RDNG4AB") {
      array[index] = "RDNGSTN";
    }
    // Additional substitutions can be applied here
  });
}

module.exports = {
  supported,
  findPisByOrigDest,
  findPisByCode,
  findByTiplocArray,
};