import fs from "node:fs";
import path from "node:path";

const [combatRatingsPath, classScalarsPath, outputPath] = process.argv.slice(2);
if (!combatRatingsPath || !classScalarsPath || !outputPath) {
  throw new Error(
    "Usage: node extract-wow335-combat-ratings.mjs <GtCombatRatings.dbc> "
      + "<GtOCTClassCombatRatingScalar.dbc> <output.json>",
  );
}

function readWdbc(filePath) {
  const data = fs.readFileSync(filePath);
  if (data.toString("ascii", 0, 4) !== "WDBC") {
    throw new Error(`${filePath} is not a WDBC file`);
  }
  const records = data.readUInt32LE(4);
  const fields = data.readUInt32LE(8);
  const recordSize = data.readUInt32LE(12);
  const recordsEnd = 20 + records * recordSize;
  if (recordsEnd > data.length) {
    throw new Error(`${filePath} has a truncated record block`);
  }
  return { data, records, fields, recordSize };
}

const combatRatings = readWdbc(combatRatingsPath);
if (combatRatings.fields !== 1 || combatRatings.recordSize !== 4 || combatRatings.records < 2_500) {
  throw new Error("GtCombatRatings.dbc has an unexpected 3.3.5a layout");
}

const classScalars = readWdbc(classScalarsPath);
if (classScalars.fields !== 2 || classScalars.recordSize !== 8) {
  throw new Error("GtOCTClassCombatRatingScalar.dbc has an unexpected 3.3.5a layout");
}

const ratingIds = Object.freeze({
  defense: 1,
  dodge: 2,
  parry: 3,
  block: 4,
  meleeHit: 5,
  rangedHit: 6,
  spellHit: 7,
  meleeCrit: 8,
  rangedCrit: 9,
  spellCrit: 10,
  resilience: 14,
  meleeHaste: 17,
  rangedHaste: 18,
  spellHaste: 19,
  expertise: 23,
  armorPenetration: 24,
});
const maxLevel = 80;
const dbcLevelStride = 100;
const ratios = {};
for (const [name, ratingId] of Object.entries(ratingIds)) {
  ratios[name] = Array.from({ length: maxLevel }, (_, index) => (
    combatRatings.data.readFloatLE(20 + (ratingId * dbcLevelStride + index) * 4)
  ));
}

const scalarById = new Map();
for (let index = 0; index < classScalars.records; index += 1) {
  const offset = 20 + index * classScalars.recordSize;
  scalarById.set(
    classScalars.data.readUInt32LE(offset),
    classScalars.data.readFloatLE(offset + 4),
  );
}

const classIds = [1, 2, 3, 4, 5, 6, 7, 8, 9, 11];
const classRatingStride = 32;
const scalars = {};
for (const classId of classIds) {
  scalars[classId] = {};
  for (const [name, ratingId] of Object.entries(ratingIds)) {
    const scalarId = (classId - 1) * classRatingStride + ratingId + 1;
    const scalar = scalarById.get(scalarId);
    if (!Number.isFinite(scalar)) {
      throw new Error(`Missing class scalar ${scalarId} for class ${classId} and ${name}`);
    }
    scalars[classId][name] = scalar;
  }
}

const output = {
  schemaVersion: 1,
  source: "World of Warcraft 3.3.5a client GtCombatRatings/GtOCTClassCombatRatingScalar",
  maxLevel,
  ratingIds,
  ratios,
  scalars,
};
fs.mkdirSync(path.dirname(outputPath), { recursive: true });
fs.writeFileSync(outputPath, `${JSON.stringify(output)}\n`);