module.exports = {
  slug: "hydration-estimate-by-weight",
  title: "Daily fluid estimate by weight (Holliday-Segar)",
  deck_category: "health",
  description: "Estimates a general daily maintenance fluid volume from body weight using the Holliday-Segar rule of thumb.",
  inputs: [
    { name: "weight_kg", type: "number", unit: "kg", required: true, description: "Body weight in kilograms", min: 0 }
  ],
  outputs: [
    { name: "daily_fluid_ml", unit: "mL/day", description: "Estimated daily maintenance fluid volume" }
  ],
  steps: [
    "This is a general rule of thumb, not a personalized prescription.",
    "For the first 10 kg of weight: 100 mL/kg/day.",
    "For the next 10 kg (weight from 10 to 20 kg): 50 mL/kg/day.",
    "For weight above 20 kg: 20 mL/kg/day.",
    "Sum the three tiers that apply and round to the nearest whole mL/day."
  ],
  constants: [
    { name: "tier1_upper_kg", value: 10, unit: "kg", source: 0 },
    { name: "tier1_rate", value: 100, unit: "mL/kg/day", source: 0 },
    { name: "tier2_upper_kg", value: 20, unit: "kg", source: 0 },
    { name: "tier2_rate", value: 50, unit: "mL/kg/day", source: 0 },
    { name: "tier3_rate", value: 20, unit: "mL/kg/day", source: 0 }
  ],
  sources: [
    { kind: "edition_page", value: "Holliday MA, Segar WE. The maintenance need for water in parenteral fluid therapy. Pediatrics. 1957;19(5):823-832.", title: "Original publication of the Holliday-Segar maintenance fluid rule", publisher: "Pediatrics (American Academy of Pediatrics)", retrieved_utc: "2026-09-30T19:45:00Z", note: "Source of the 100/50/20 mL-per-kg tiered rule used here as a general daily fluid estimate for any body weight." }
  ],
  disclaimer: "General formula only. Not medical advice. Dosing decisions belong to a licensed clinician and the product's label.",
  questionText(inputs) {
    return `Using the Holliday-Segar general rule of thumb, what is the estimated daily fluid need for a person weighing ${inputs.weight_kg} kg?`;
  },
  run(inputs) {
    const { weight_kg } = inputs;
    if (typeof weight_kg !== "number" || weight_kg <= 0) throw new Error("weight_kg must be a positive number");
    let remaining = weight_kg;
    let total = 0;
    const tier1 = Math.min(remaining, 10);
    total += tier1 * 100;
    remaining -= tier1;
    if (remaining > 0) {
      const tier2 = Math.min(remaining, 10);
      total += tier2 * 50;
      remaining -= tier2;
    }
    if (remaining > 0) {
      total += remaining * 20;
    }
    const dailyFluid = Math.round(total);
    return { answer: `${dailyFluid} mL/day`, values: { daily_fluid_ml: dailyFluid } };
  },
  examples: [
    {
      name: "worked example",
      inputs: { weight_kg: 70 },
      expected: { answer: "2500 mL/day" },
      check: "First 10 kg: 10*100=1000. Next 10 kg: 10*50=500. Remaining 50 kg: 50*20=1000. Total = 1000+500+1000 = 2500."
    },
    {
      name: "test vector: small child weight",
      inputs: { weight_kg: 8 },
      expected: { answer: "800 mL/day" },
      check: "Only tier 1 applies: 8*100 = 800."
    }
  ]
};