const IN_TO_CM = 2.54; // exact, international inch

module.exports = {
  slug: "ideal-body-weight-devine",
  title: "Ideal body weight (Devine formula)",
  deck_category: "health",
  description: "Estimates ideal body weight in kilograms from sex and height using the Devine formula.",
  inputs: [
    { name: "sex", type: "string", required: true, description: "Biological sex used by the equation", enum: ["male", "female"] },
    { name: "height", type: "number", unit: "cm or in", required: true, description: "Height", min: 0 },
    { name: "height_unit", type: "string", required: true, description: "Unit of the height value", enum: ["cm", "in"] }
  ],
  outputs: [
    { name: "ideal_body_weight_kg", unit: "kg", description: "Estimated ideal body weight" }
  ],
  steps: [
    "Convert height to inches: in = cm / 2.54 if given in centimeters.",
    "The Devine formula is defined for height at or above 60 inches (5 feet); heights below that use 60 inches as the base per the original formula's construction.",
    "For males: ideal_body_weight_kg = 50 + 2.3 * (height_in - 60).",
    "For females: ideal_body_weight_kg = 45.5 + 2.3 * (height_in - 60).",
    "Round the result to 1 decimal place."
  ],
  constants: [
    { name: "in_to_cm", value: 2.54, unit: "cm per in", source: 1 },
    { name: "male_base_kg", value: 50, unit: "kg", source: 0 },
    { name: "female_base_kg", value: 45.5, unit: "kg", source: 0 },
    { name: "per_inch_over_five_feet", value: 2.3, unit: "kg per in", source: 0 },
    { name: "base_height_in", value: 60, unit: "in", source: 0 }
  ],
  sources: [
    { kind: "edition_page", value: "Devine BJ. Gentamicin therapy. Drug Intell Clin Pharm. 1974;8:650-655.", title: "Original publication of the Devine ideal body weight formula", publisher: "Drug Intelligence and Clinical Pharmacy", retrieved_utc: "2026-09-30T19:15:00Z", note: "Source of the 50/45.5 base and 2.3 kg per inch coefficients." },
    { kind: "edition_page", value: "International Yard and Pound Agreement, 1959", title: "Exact inch to centimeter conversion factor", publisher: "NIST Handbook 44, Appendix C", retrieved_utc: "2026-09-30T19:15:00Z", note: "Defines 1 in = 2.54 cm exactly." }
  ],
  disclaimer: "General formula only. Not medical advice. Dosing decisions belong to a licensed clinician and the product's label.",
  questionText(inputs) {
    return `What is the Devine ideal body weight for a ${inputs.sex} who is ${inputs.height} ${inputs.height_unit} tall?`;
  },
  run(inputs) {
    const { sex, height, height_unit } = inputs;
    if (sex !== "male" && sex !== "female") throw new Error("sex must be male or female");
    if (typeof height !== "number" || height <= 0) throw new Error("height must be a positive number");
    let heightIn;
    if (height_unit === "cm") heightIn = height / IN_TO_CM;
    else if (height_unit === "in") heightIn = height;
    else throw new Error("height_unit must be cm or in");
    const heightInForFormula = Math.max(heightIn, 60);
    const base = sex === "male" ? 50 : 45.5;
    const ibwRaw = base + 2.3 * (heightInForFormula - 60);
    const ibw = Math.round(ibwRaw * 10) / 10;
    return { answer: `${ibw.toFixed(1)} kg`, values: { ideal_body_weight_kg: ibw } };
  },
  examples: [
    {
      name: "worked example",
      inputs: { sex: "male", height: 180, height_unit: "cm" },
      expected: { answer: "75.0 kg" },
      check: "180 / 2.54 = 70.86614 in; 70.86614 - 60 = 10.86614; 10.86614 * 2.3 = 24.99212; 50 + 24.99212 = 74.99212, rounds to 75.0."
    },
    {
      name: "test vector: female, inches",
      inputs: { sex: "female", height: 64, height_unit: "in" },
      expected: { answer: "54.7 kg" },
      check: "64 - 60 = 4; 4 * 2.3 = 9.2; 45.5 + 9.2 = 54.7."
    }
  ]
};