export interface IElement {
  name: string;
  radius: number;
}

export type TPeriodicTable = Record<string, IElement>;

/**
 * Layout and visual grouping for the periodic-table s, p, d, and f blocks.
 * Here `f` covers the complete detached lanthanide and actinide series.
 */
export type ElementBlock = "s" | "p" | "d" | "f";

/**
 * @description Chemical-element data plus conventional periodic-table
 * placement. `period` and `group` describe the chemistry; `row` and `column`
 * are one-based UI grid coordinates. The detached lanthanide and actinide
 * series use rows 8 and 9, columns 3–17, with `group: null`.
 *
 * @example
 * ```ts
 * const carbon = PeriodicTableElements.find(({ symbol }) => symbol === "C");
 * // carbon?.period === 2; carbon?.group === 14
 * // carbon?.row === 2; carbon?.column === 14
 * ```
 */
export interface PeriodicTableElement extends IElement {
  /** Standard chemical symbol, for example `"C"` or `"Fe"`. */
  readonly symbol: string;
  /** Atomic number, from 1 for hydrogen through 118 for oganesson. */
  readonly atomicNumber: number;
  /** Horizontal period in the chemical periodic table, from 1 through 7. */
  readonly period: number;
  /**
   * International Union of Pure and Applied Chemistry (IUPAC) group from
   * 1 through 18, or `null` for the detached f-block.
   */
  readonly group: number | null;
  /** Periodic-table block classification used for layout and visual grouping. */
  readonly block: ElementBlock;
  /** One-based visual row; rows 8 and 9 hold the detached f-block. */
  readonly row: number;
  /** One-based visual column in the conventional 18-column layout. */
  readonly column: number;
}

/**
 * Neutral-atom van der Waals radii in Å. The values are the surface radii
 * published by Charry & Tkatchenko (JCTC 2024, DOI 10.1021/acs.jctc.4c00784),
 * converted from bohr. Keeping these separate from the covalent radii below is
 * important: Spacefill is a physical size model, not a scaled bond model.
 */
export const VanDerWaalsRadii: Readonly<Record<string, number>> = {
  H: 1.675,
  // biome-ignore lint/suspicious/noApproximativeNumericConstant: published radius is exactly 1.414 Å.
  He: 1.414,
  Li: 2.799,
  Be: 2.269,
  B: 2.08,
  C: 1.91,
  N: 1.798,
  O: 1.715,
  F: 1.631,
  Ne: 1.554,
  Na: 2.797,
  Mg: 2.485,
  Al: 2.412,
  Si: 2.265,
  P: 2.139,
  S: 2.063,
  Cl: 1.981,
  Ar: 1.905,
  K: 3.037,
  Ca: 2.792,
  Sc: 2.597,
  Ti: 2.608,
  V: 2.557,
  Cr: 2.54,
  Mn: 2.468,
  Fe: 2.436,
  Co: 2.395,
  Ni: 2.355,
  Cu: 2.342,
  Zn: 2.277,
  Ga: 2.362,
  Ge: 2.288,
  As: 2.196,
  Se: 2.186,
  Br: 2.087,
  Kr: 2.021,
  Rb: 3.08,
  Sr: 2.873,
  Y: 2.794,
  Zr: 2.651,
  Nb: 2.6,
  Mo: 2.557,
  Tc: 2.522,
  Ru: 2.489,
  Rh: 2.455,
  Pd: 2.153,
  Ag: 2.395,
  Cd: 2.334,
  In: 2.453,
  Sn: 2.382,
  Sb: 2.312,
  Te: 2.271,
  I: 2.225,
  Xe: 2.167,
  Cs: 3.181,
  Ba: 3.009,
  La: 2.909,
  Ce: 2.89,
  Pr: 2.912,
  Nd: 2.896,
  Pm: 2.88,
  Sm: 2.863,
  Eu: 2.845,
  Gd: 2.785,
  Tb: 2.814,
  Dy: 2.801,
  Ho: 2.779,
  Er: 2.764,
  Tm: 2.747,
  Yb: 2.734,
  Lu: 2.728,
  Hf: 2.619,
  Ta: 2.498,
  W: 2.466,
  Re: 2.436,
  Os: 2.407,
  Ir: 2.388,
  Pt: 2.348,
  Au: 2.254,
  Hg: 2.235,
  Tl: 2.362,
  Pb: 2.342,
  Bi: 2.348,
  Po: 2.319,
  At: 2.304,
  Rn: 2.245,
  Fr: 3.077,
  Ra: 2.966,
  Ac: 2.886,
  Th: 2.916,
  Pa: 2.774,
  U: 2.705,
  Np: 2.767,
  Pu: 2.715,
  Am: 2.709,
  Cm: 2.746,
  Bk: 2.694,
  Cf: 2.683,
  Es: 2.672,
  Fm: 2.656,
  Md: 2.641,
  No: 2.644,
  Lr: 3.08,
  Rf: 2.651,
  Db: 2.304,
  Sg: 2.288,
  Bh: 2.271,
  Hs: 2.254,
  Mt: 2.236,
  Ds: 2.216,
  Rg: 2.217,
  Cn: 2.174,
  Nh: 2.186,
  Fl: 2.206,
  Mc: 2.482,
  Ts: 2.508,
  Og: 2.413,
};

const METAL_ELEMENTS = new Set([
  "Li",
  "Be",
  "Na",
  "Mg",
  "Al",
  "K",
  "Ca",
  "Sc",
  "Ti",
  "V",
  "Cr",
  "Mn",
  "Fe",
  "Co",
  "Ni",
  "Cu",
  "Zn",
  "Ga",
  "Rb",
  "Sr",
  "Y",
  "Zr",
  "Nb",
  "Mo",
  "Tc",
  "Ru",
  "Rh",
  "Pd",
  "Ag",
  "Cd",
  "In",
  "Sn",
  "Cs",
  "Ba",
  "La",
  "Ce",
  "Pr",
  "Nd",
  "Pm",
  "Sm",
  "Eu",
  "Gd",
  "Tb",
  "Dy",
  "Ho",
  "Er",
  "Tm",
  "Yb",
  "Lu",
  "Hf",
  "Ta",
  "W",
  "Re",
  "Os",
  "Ir",
  "Pt",
  "Au",
  "Hg",
  "Tl",
  "Pb",
  "Bi",
  "Po",
  "Fr",
  "Ra",
  "Ac",
  "Th",
  "Pa",
  "U",
  "Np",
  "Pu",
  "Am",
  "Cm",
  "Bk",
  "Cf",
  "Es",
  "Fm",
  "Md",
  "No",
  "Lr",
  "Rf",
  "Db",
  "Sg",
  "Bh",
  "Hs",
  "Mt",
  "Ds",
  "Rg",
  "Cn",
  "Nh",
  "Fl",
  "Mc",
  "Lv",
]);

/** Normalize aromatic/lowercase element symbols to standard notation. */
export function normalizeElement(element: string): string {
  if (element.length === 0) return element;
  return element[0].toUpperCase() + element.slice(1).toLowerCase();
}

export function getVanDerWaalsRadius(element: string): number {
  const normalized = normalizeElement(element);
  return (
    VanDerWaalsRadii[normalized] ??
    Math.max((PeriodicTable[normalized]?.radius ?? 0.8) + 0.8, 1.5)
  );
}

export function isMetalElement(element: string): boolean {
  return METAL_ELEMENTS.has(normalizeElement(element));
}

export const PeriodicTable: TPeriodicTable = {
  H: { radius: 0.38, name: "Hydrogen" },
  He: { radius: 0.32, name: "Helium" },
  Li: { radius: 1.34, name: "Lithium" },
  Be: { radius: 0.9, name: "Beryllium" },
  B: { radius: 0.82, name: "Boron" },
  C: { radius: 0.77, name: "Carbon" },
  N: { radius: 0.75, name: "Nitrogen" },
  O: { radius: 0.73, name: "Oxygen" },
  F: { radius: 0.71, name: "Fluorine" },
  Ne: { radius: 0.69, name: "Neon" },

  Na: { radius: 1.54, name: "Sodium" },
  Mg: { radius: 1.3, name: "Magnesium" },
  Al: { radius: 1.18, name: "Aluminum" },
  Si: { radius: 1.11, name: "Silicon" },
  P: { radius: 1.06, name: "Phosphorus" },
  S: { radius: 1.02, name: "Sulfur" },
  Cl: { radius: 0.99, name: "Chlorine" },
  Ar: { radius: 0.97, name: "Argon" },

  K: { radius: 1.96, name: "Potassium" },
  Ca: { radius: 1.74, name: "Calcium" },
  Sc: { radius: 1.44, name: "Scandium" },
  Ti: { radius: 1.32, name: "Titanium" },
  V: { radius: 1.22, name: "Vanadium" },
  Cr: { radius: 1.18, name: "Chromium" },
  Mn: { radius: 1.17, name: "Manganese" },
  Fe: { radius: 1.17, name: "Iron" },
  Co: { radius: 1.16, name: "Cobalt" },
  Ni: { radius: 1.15, name: "Nickel" },
  Cu: { radius: 1.17, name: "Copper" },
  Zn: { radius: 1.25, name: "Zinc" },
  Ga: { radius: 1.26, name: "Gallium" },
  Ge: { radius: 1.22, name: "Germanium" },
  As: { radius: 1.19, name: "Arsenic" },
  Se: { radius: 1.2, name: "Selenium" },
  Br: { radius: 1.2, name: "Bromine" },
  Kr: { radius: 1.16, name: "Krypton" },

  Rb: { radius: 2.1, name: "Rubidium" },
  Sr: { radius: 1.85, name: "Strontium" },
  Y: { radius: 1.63, name: "Yttrium" },
  Zr: { radius: 1.54, name: "Zirconium" },
  Nb: { radius: 1.47, name: "Niobium" },
  Mo: { radius: 1.38, name: "Molybdenum" },
  Tc: { radius: 1.28, name: "Technetium" },
  Ru: { radius: 1.25, name: "Ruthenium" },
  Rh: { radius: 1.25, name: "Rhodium" },
  Pd: { radius: 1.2, name: "Palladium" },
  Ag: { radius: 1.28, name: "Silver" },
  Cd: { radius: 1.36, name: "Cadmium" },
  In: { radius: 1.42, name: "Indium" },
  Sn: { radius: 1.4, name: "Tin" },
  Sb: { radius: 1.4, name: "Antimony" },
  Te: { radius: 1.36, name: "Tellurium" },
  I: { radius: 1.33, name: "Iodine" },
  Xe: { radius: 1.31, name: "Xenon" },

  Cs: { radius: 2.25, name: "Cesium" },
  Ba: { radius: 1.98, name: "Barium" },
  La: { radius: 1.69, name: "Lanthanum" },
  Ce: { radius: 1.65, name: "Cerium" },
  Pr: { radius: 1.65, name: "Praseodymium" },
  Nd: { radius: 1.64, name: "Neodymium" },
  Pm: { radius: 1.63, name: "Promethium" },
  Sm: { radius: 1.62, name: "Samarium" },
  Eu: { radius: 1.61, name: "Europium" },
  Gd: { radius: 1.6, name: "Gadolinium" },
  Tb: { radius: 1.59, name: "Terbium" },
  Dy: { radius: 1.58, name: "Dysprosium" },
  Ho: { radius: 1.57, name: "Holmium" },
  Er: { radius: 1.56, name: "Erbium" },
  Tm: { radius: 1.55, name: "Thulium" },
  Yb: { radius: 1.54, name: "Ytterbium" },
  Lu: { radius: 1.53, name: "Lutetium" },

  Hf: { radius: 1.52, name: "Hafnium" },
  Ta: { radius: 1.51, name: "Tantalum" },
  W: { radius: 1.5, name: "Tungsten" },
  Re: { radius: 1.49, name: "Rhenium" },
  Os: { radius: 1.48, name: "Osmium" },
  Ir: { radius: 1.47, name: "Iridium" },
  Pt: { radius: 1.46, name: "Platinum" },
  Au: { radius: 1.45, name: "Gold" },
  Hg: { radius: 1.44, name: "Mercury" },
  Tl: { radius: 1.43, name: "Thallium" },
  Pb: { radius: 1.42, name: "Lead" },
  Bi: { radius: 1.41, name: "Bismuth" },
  Po: { radius: 1.4, name: "Polonium" },
  At: { radius: 1.39, name: "Astatine" },
  Rn: { radius: 1.38, name: "Radon" },

  Fr: { radius: 1.37, name: "Francium" },
  Ra: { radius: 1.36, name: "Radium" },
  Ac: { radius: 1.35, name: "Actinium" },
  Th: { radius: 1.34, name: "Thorium" },
  Pa: { radius: 1.33, name: "Protactinium" },
  U: { radius: 1.32, name: "Uranium" },
  Np: { radius: 1.31, name: "Neptunium" },
  Pu: { radius: 1.3, name: "Plutonium" },
  Am: { radius: 1.29, name: "Americium" },
  Cm: { radius: 1.28, name: "Curium" },
  Bk: { radius: 1.27, name: "Berkelium" },
  Cf: { radius: 1.26, name: "Californium" },
  Es: { radius: 1.25, name: "Einsteinium" },
  Fm: { radius: 1.24, name: "Fermium" },
  Md: { radius: 1.23, name: "Mendelevium" },
  No: { radius: 1.22, name: "Nobelium" },
  Lr: { radius: 1.21, name: "Lawrencium" },

  Rf: { radius: 1.2, name: "Rutherfordium" },
  Db: { radius: 1.19, name: "Dubnium" },
  Sg: { radius: 1.18, name: "Seaborgium" },
  Bh: { radius: 1.17, name: "Bohrium" },
  Hs: { radius: 1.16, name: "Hassium" },
  Mt: { radius: 1.15, name: "Meitnerium" },
  Ds: { radius: 1.14, name: "Darmstadtium" },
  Rg: { radius: 1.13, name: "Roentgenium" },
  Cn: { radius: 1.12, name: "Copernicium" },
  Nh: { radius: 1.11, name: "Nihonium" },
  Fl: { radius: 1.1, name: "Flerovium" },
  Mc: { radius: 1.09, name: "Moscovium" },
  Lv: { radius: 1.08, name: "Livermorium" },
  Ts: { radius: 1.07, name: "Tennessine" },
  Og: { radius: 1.06, name: "Oganesson" },
} as const;

interface ElementPlacement {
  period: number;
  group: number | null;
  block: ElementBlock;
  row: number;
  column: number;
}

interface PeriodSegment {
  startColumn: number;
  symbols: readonly string[];
}

interface PeriodRow {
  period: number;
  segments: readonly PeriodSegment[];
}

const MainPeriodRows: readonly PeriodRow[] = [
  {
    period: 1,
    segments: [
      { startColumn: 1, symbols: ["H"] },
      { startColumn: 18, symbols: ["He"] },
    ],
  },
  {
    period: 2,
    segments: [
      { startColumn: 1, symbols: ["Li", "Be"] },
      {
        startColumn: 13,
        symbols: ["B", "C", "N", "O", "F", "Ne"],
      },
    ],
  },
  {
    period: 3,
    segments: [
      { startColumn: 1, symbols: ["Na", "Mg"] },
      {
        startColumn: 13,
        symbols: ["Al", "Si", "P", "S", "Cl", "Ar"],
      },
    ],
  },
  {
    period: 4,
    segments: [
      {
        startColumn: 1,
        symbols: [
          "K",
          "Ca",
          "Sc",
          "Ti",
          "V",
          "Cr",
          "Mn",
          "Fe",
          "Co",
          "Ni",
          "Cu",
          "Zn",
          "Ga",
          "Ge",
          "As",
          "Se",
          "Br",
          "Kr",
        ],
      },
    ],
  },
  {
    period: 5,
    segments: [
      {
        startColumn: 1,
        symbols: [
          "Rb",
          "Sr",
          "Y",
          "Zr",
          "Nb",
          "Mo",
          "Tc",
          "Ru",
          "Rh",
          "Pd",
          "Ag",
          "Cd",
          "In",
          "Sn",
          "Sb",
          "Te",
          "I",
          "Xe",
        ],
      },
    ],
  },
  {
    period: 6,
    segments: [
      { startColumn: 1, symbols: ["Cs", "Ba"] },
      {
        startColumn: 4,
        symbols: [
          "Hf",
          "Ta",
          "W",
          "Re",
          "Os",
          "Ir",
          "Pt",
          "Au",
          "Hg",
          "Tl",
          "Pb",
          "Bi",
          "Po",
          "At",
          "Rn",
        ],
      },
    ],
  },
  {
    period: 7,
    segments: [
      { startColumn: 1, symbols: ["Fr", "Ra"] },
      {
        startColumn: 4,
        symbols: [
          "Rf",
          "Db",
          "Sg",
          "Bh",
          "Hs",
          "Mt",
          "Ds",
          "Rg",
          "Cn",
          "Nh",
          "Fl",
          "Mc",
          "Lv",
          "Ts",
          "Og",
        ],
      },
    ],
  },
];

const Lanthanides = [
  "La",
  "Ce",
  "Pr",
  "Nd",
  "Pm",
  "Sm",
  "Eu",
  "Gd",
  "Tb",
  "Dy",
  "Ho",
  "Er",
  "Tm",
  "Yb",
  "Lu",
] as const;

const Actinides = [
  "Ac",
  "Th",
  "Pa",
  "U",
  "Np",
  "Pu",
  "Am",
  "Cm",
  "Bk",
  "Cf",
  "Es",
  "Fm",
  "Md",
  "No",
  "Lr",
] as const;

function blockForMainTable(symbol: string, group: number): ElementBlock {
  if (group <= 2 || symbol === "He") {
    return "s";
  }
  if (group <= 12) {
    return "d";
  }
  return "p";
}

function createElementPlacements(): ReadonlyMap<string, ElementPlacement> {
  const placements = new Map<string, ElementPlacement>();

  for (const row of MainPeriodRows) {
    for (const segment of row.segments) {
      segment.symbols.forEach((symbol, index) => {
        const column = segment.startColumn + index;
        placements.set(symbol, {
          period: row.period,
          group: column,
          block: blockForMainTable(symbol, column),
          row: row.period,
          column,
        });
      });
    }
  }

  const addFBlock = (
    symbols: readonly string[],
    period: number,
    row: number,
  ) => {
    symbols.forEach((symbol, index) => {
      placements.set(symbol, {
        period,
        group: null,
        block: "f",
        row,
        column: index + 3,
      });
    });
  };

  addFBlock(Lanthanides, 6, 8);
  addFBlock(Actinides, 7, 9);

  return placements;
}

const ElementPlacements = createElementPlacements();

/**
 * @description Complete element catalog in atomic-number order. Each frozen
 * entry carries one-based coordinates for the conventional 18-column layout.
 * The f-block—the lanthanide and actinide series commonly drawn below the main
 * table—occupies rows 8 and 9. The array and every entry are frozen at runtime.
 *
 * @example
 * ```ts
 * const iron = PeriodicTableElements.find(({ symbol }) => symbol === "Fe");
 * console.log(iron?.atomicNumber, iron?.row, iron?.column); // 26, 4, 8
 * ```
 */
export const PeriodicTableElements: readonly PeriodicTableElement[] =
  Object.freeze(
    Object.entries(PeriodicTable).map(([symbol, element], index) => {
      const placement = ElementPlacements.get(symbol);
      if (!placement) {
        throw new Error(`Missing periodic-table placement for ${symbol}`);
      }

      return Object.freeze({
        symbol,
        ...element,
        atomicNumber: index + 1,
        ...placement,
      });
    }),
  );