'use strict';

const fs = require('node:fs');
const path = require('node:path');
const { parseDsl } = require('../dsl-parser');
const { loadAtlasDirs } = require('../atlas-loader');
const { buildMap } = require('../builder');

const USAGE = 'usage: sporel-mapper build <spec.txt> <out.json> [--atlas-dir <path> ...]\n';

function parseArgs(args) {
  const positional = [];
  const atlasDirs = [];
  let i = 0;
  while (i < args.length) {
    const a = args[i];
    if (a === '--atlas-dir') {
      if (i + 1 >= args.length) {
        throw new Error(`--atlas-dir requires a path`);
      }
      atlasDirs.push(args[i + 1]);
      i += 2;
    } else {
      positional.push(a);
      i += 1;
    }
  }
  return { positional, atlasDirs };
}

function run(args, { out, err }) {
  let parsed;
  try {
    parsed = parseArgs(args);
  } catch (e) {
    err.write(`error: ${e.message}\n${USAGE}`);
    return 1;
  }
  if (parsed.positional.length !== 2) {
    err.write(USAGE);
    return 1;
  }
  const [specPath, outPath] = parsed.positional;

  let dslText;
  try {
    dslText = fs.readFileSync(specPath, 'utf8');
  } catch (e) {
    err.write(`error: cannot read ${specPath}: ${e.message}\n`);
    return 1;
  }

  let ast;
  try {
    ast = parseDsl(dslText);
  } catch (e) {
    const line = e.line || '?';
    err.write(`${specPath}:${line}: ${e.message}\n`);
    return 1;
  }

  let registry;
  try {
    const result = loadAtlasDirs(parsed.atlasDirs);
    registry = result.registry;
    for (const w of result.warnings) {
      err.write(`warning: ${w}\n`);
    }
  } catch (e) {
    err.write(`error: ${e.message}\n`);
    return 1;
  }

  const defaultId = path.basename(outPath, path.extname(outPath));
  let map;
  try {
    map = buildMap(ast, registry, { defaultId });
  } catch (e) {
    const line = e.line || '?';
    err.write(`${specPath}:${line}: ${e.message}\n`);
    return 1;
  }

  try {
    fs.writeFileSync(outPath, JSON.stringify(map, null, 2) + '\n');
  } catch (e) {
    err.write(`error: cannot write ${outPath}: ${e.message}\n`);
    return 1;
  }

  return 0;
}

module.exports = { run };