How to Build a Garage Door Calculator

interface GarageDoorInput {
  widthFt: number;
  heightFt: number;
  material: 'steel' | 'aluminum' | 'wood' | 'composite' | 'fiberglass';
  insulation: 'R0' | 'R8' | 'R12' | 'R16';
  windowCount: number;
  openerType: 'chain' | 'belt' | 'wall-mount' | 'none';
  includeInstallation: boolean;
  }

  interface CostEstimate {
  doorCost: { low: number; high: number };
  openerCost: { low: number; high: number };
  installationCost: { low: number; high: number };
  totalLow: number;
  totalHigh: number;
  }

  const BASE_COST: Record<string, { low: number; high: number }> = {
  '8x7': { low: 750, high: 1200 },
  '9x7': { low: 800, high: 1400 },
  '9x8': { low: 900, high: 1500 },
  '16x7': { low: 1100, high: 2500 },
  '16x8': { low: 1300, high: 2800 },
  '18x7': { low: 1600, high: 3200 },
  '18x8': { low: 1800, high: 4000 },
  };

  const MATERIAL_MULTIPLIER = { steel: 1.0, aluminum: 1.1, wood: 2.2, composite: 1.4, fiberglass: 1.2 };
  const INSULATION_ADDER = { R0: 0, R8: 200, R12: 275, R16: 400 };
  const OPENER_COST = {
  chain: { low: 200, high: 300 },
  belt: { low: 300, high: 450 },
  'wall-mount': { low: 400, high: 600 },
  none: { low: 0, high: 0 }
  };

  function estimateGarageDoor(input: GarageDoorInput): CostEstimate {
  const sizeKey = `${input.widthFt}x${input.heightFt}`;
  const base = BASE_COST[sizeKey] ?? {
    low: input.widthFt * input.heightFt * 12,
    high: input.widthFt * input.heightFt * 22
  };

  const mult = MATERIAL_MULTIPLIER[input.material];
  const insulation = INSULATION_ADDER[input.insulation];
  const windowCost = input.windowCount * 120;
  const isDouble = input.widthFt >= 14;

  const doorLow = Math.round(base.low * mult + insulation + windowCost);
  const doorHigh = Math.round(base.high * mult + insulation + windowCost);
  const opener = OPENER_COST[input.openerType];
  const install = input.includeInstallation
    ? (isDouble ? { low: 300, high: 700 } : { low: 200, high: 500 })
    : { low: 0, high: 0 };

  return {
    doorCost: { low: doorLow, high: doorHigh },
    openerCost: opener,
    installationCost: install,
    totalLow: doorLow + opener.low + install.low,
    totalHigh: doorHigh + opener.high + install.high
  };
  }