test.d

import std.stdio: writeln;
import std.array: split;
import std.string: strip, indexOf;
import re = std.regex;

struct Atom {
  string name;
  short quantity;
}

//struct Molecule {
//  Atom[] atoms;
//}

struct Molecule {
  string[] atoms;
}

struct ChemicalEquation {
  Molecule[] reactants;
  Molecule[] products;
}

void main() {
  auto input = "Al + Fe2O4 -> Fe + Al2O3";

  try {
    auto tokens = stringToChemicalEquation(input);

    writeln(tokens);
  } catch (Exception e) {
    writeln(e.msg);
  }
}

ChemicalEquation stringToChemicalEquation(string str) {
  if (indexOf(str, "->") == -1)
    throw new Exception("Il manque un produit à la réaction !");

  auto chemicalEquation = ChemicalEquation();

  auto parts = split(str, "->");
  parts = trimArray(parts);

  auto reactants = split(parts[0], "+");
  reactants = trimArray(reactants);

  auto products = split(parts[1], "+");
  products = trimArray(products);

  Molecule[] reactantsMolecules = [];

  for (auto i = 0 ; i < reactants.length ; i++) {
    auto product = reactants[i];
    auto molecule = stringToMolecule(product);

    reactantsMolecules ~= molecule;
  }

  Molecule[] productsMolecules = [];

  for (auto i = 0 ; i < products.length ; i++) {
    auto product = products[i];
    auto molecule = stringToMolecule(product);

    productsMolecules ~= molecule;
  }

  chemicalEquation.reactants = reactantsMolecules;
  chemicalEquation.products = productsMolecules;

  return chemicalEquation;
}

Molecule stringToMolecule(string str) {
  auto atoms1 = re.matchAll(str, re.regex("[A-Z][a-z]*[0-9]*"));

  string[] atoms2 = [];

  foreach (atom ; atoms1)
    atoms2 ~= atom.hit;

  auto molecule = Molecule();
  molecule.atoms = atoms2;

  return molecule;
}

string[] trimArray(string[] arr) {
  for (auto i = 0 ; i < arr.length ; i++)
    arr[i] = strip(arr[i]);

  return arr;
}