oil-formula-calculator/frontend/src/__tests__/kitCost.test.js

import { describe, it, expect } from 'vitest'
import prodData from './fixtures/production-data.json'
import { KITS } from '../config/kits'

const oils = prodData.oils

// ---------------------------------------------------------------------------
// Replicate kit cost calculation logic from useKitCost.js (pure functions)
// ---------------------------------------------------------------------------

function resolveOilName(kitOilName) {
  if (oils[kitOilName]) return kitOilName
  const match = Object.keys(oils).find(n => n.endsWith(kitOilName) && n !== kitOilName)
  return match || kitOilName
}

function calcKitPerDrop(kit) {
  const resolved = kit.oils.map(resolveOilName)
  const bc = kit.bottleCount || {}
  let totalBottlePrice = 0
  const oilBottlePrices = {}
  for (const name of resolved) {
    const meta = oils[name]
    const count = bc[name] || 1
    const bp = meta ? meta.bottlePrice * count : 0
    oilBottlePrices[name] = bp
    totalBottlePrice += bp
  }
  if (totalBottlePrice === 0) return {}

  const totalValue = totalBottlePrice + (kit.accessoryValue || 0)
  const discountRate = Math.min(kit.price / totalValue, 1)
  const perDrop = {}
  for (const name of resolved) {
    const meta = oils[name]
    const count = bc[name] || 1
    const bp = oilBottlePrices[name]
    const kitCostForOil = bp * discountRate
    const totalDrops = meta ? meta.dropCount * count : 1
    perDrop[name] = totalDrops > 0 ? kitCostForOil / totalDrops : 0
  }
  return perDrop
}

function canMakeRecipe(kit, recipe) {
  const resolvedSet = new Set(kit.oils.map(resolveOilName))
  return recipe.ingredients.every(ing => resolvedSet.has(ing.oil))
}

function calcRecipeCostWithKit(kitPerDrop, recipe) {
  return recipe.ingredients.reduce((sum, ing) => {
    return sum + (kitPerDrop[ing.oil] || 0) * ing.drops
  }, 0)
}

function calcOriginalCost(recipe) {
  return recipe.ingredients.reduce((sum, ing) => {
    const meta = oils[ing.oil]
    if (!meta || !meta.dropCount) return sum
    return sum + (meta.bottlePrice / meta.dropCount) * ing.drops
  }, 0)
}

// ---------------------------------------------------------------------------
// Kit Configuration
// ---------------------------------------------------------------------------
describe('Kit Configuration', () => {
  it('has 4 kits defined', () => {
    expect(KITS).toHaveLength(4)
  })

  it('each kit has required fields', () => {
    for (const kit of KITS) {
      expect(kit).toHaveProperty('id')
      expect(kit).toHaveProperty('name')
      expect(kit).toHaveProperty('price')
      expect(kit).toHaveProperty('oils')
      expect(kit.price).toBeGreaterThan(0)
      expect(kit.oils.length).toBeGreaterThan(0)
    }
  })

  it('all kits include coconut oil', () => {
    for (const kit of KITS) {
      expect(kit.oils).toContain('椰子油')
    }
  })

  it('kit ids are unique', () => {
    const ids = KITS.map(k => k.id)
    expect(new Set(ids).size).toBe(ids.length)
  })

  it('芳香调理 has 9 oils at ¥1575', () => {
    const kit = KITS.find(k => k.id === 'aroma')
    expect(kit.price).toBe(1575)
    expect(kit.oils).toHaveLength(9)
  })

  it('家庭医生 has 11 oils at ¥2250', () => {
    const kit = KITS.find(k => k.id === 'family')
    expect(kit.price).toBe(2250)
    expect(kit.oils).toHaveLength(11)
  })

  it('居家呵护 has 23 oils at ¥3988', () => {
    const kit = KITS.find(k => k.id === 'home3988')
    expect(kit.price).toBe(3988)
    expect(kit.oils).toHaveLength(23)
  })

  it('全精油 has 80 oils at ¥17700 with bottleCount for coconut oil', () => {
    const kit = KITS.find(k => k.id === 'full')
    expect(kit.price).toBe(17700)
    expect(kit.oils.length).toBe(80)
    expect(kit.bottleCount).toBeDefined()
    expect(kit.bottleCount['椰子油']).toBeCloseTo(2.57, 2)
  })
})

// ---------------------------------------------------------------------------
// Oil Name Resolution
// ---------------------------------------------------------------------------
describe('Oil Name Resolution', () => {
  it('resolves exact match', () => {
    expect(resolveOilName('薰衣草')).toBe('薰衣草')
    expect(resolveOilName('乳香')).toBe('乳香')
  })

  it('resolves 牛至 to 西班牙牛至 via endsWith', () => {
    expect(resolveOilName('牛至')).toBe('西班牙牛至')
  })

  it('does NOT resolve 牛至 to 牛至呵护', () => {
    expect(resolveOilName('牛至')).not.toBe('牛至呵护')
  })

  it('returns original name for unknown oil', () => {
    expect(resolveOilName('不存在的油')).toBe('不存在的油')
  })
})

// ---------------------------------------------------------------------------
// Kit Cost Calculation
// ---------------------------------------------------------------------------
describe('Kit Cost Calculation', () => {
  it('discount rate is always <= 1 (kit never more expensive than buying individually)', () => {
    for (const kit of KITS) {
      const perDrop = calcKitPerDrop(kit)
      for (const [name, ppd] of Object.entries(perDrop)) {
        const meta = oils[name]
        if (!meta || !meta.dropCount) continue
        const originalPpd = meta.bottlePrice / meta.dropCount
        expect(ppd).toBeLessThanOrEqual(originalPpd + 0.001) // tiny float tolerance
      }
    }
  })

  it('家庭医生 discount is ~32-33%', () => {
    const kit = KITS.find(k => k.id === 'family')
    const bc = kit.bottleCount || {}
    let totalBp = 0
    for (const name of kit.oils) {
      const resolved = resolveOilName(name)
      const meta = oils[resolved]
      totalBp += meta ? meta.bottlePrice * (bc[resolved] || 1) : 0
    }
    const totalValue = totalBp + (kit.accessoryValue || 0)
    const discount = 1 - kit.price / totalValue
    expect(discount).toBeGreaterThan(0.30)
    expect(discount).toBeLessThan(0.40)
  })

  it('kit cost for a recipe is less than original cost', () => {
    const kit = KITS.find(k => k.id === 'family')
    const perDrop = calcKitPerDrop(kit)
    // 灰指甲: 西班牙牛至 + 椰子油
    const recipe = prodData.recipes.find(r => r.name === '灰指甲')
    if (recipe && canMakeRecipe(kit, recipe)) {
      const kitCost = calcRecipeCostWithKit(perDrop, recipe)
      const origCost = calcOriginalCost(recipe)
      expect(kitCost).toBeLessThan(origCost)
      expect(kitCost).toBeGreaterThan(0)
    }
  })

  it('全精油 bottleCount 2.57 makes coconut oil cheaper per drop than without multiplier', () => {
    const fullKit = KITS.find(k => k.id === 'full')
    const perDrop = calcKitPerDrop(fullKit)
    // With 2.57 bottles, per-drop cost should be roughly 1/2.57 of single-bottle kit cost
    // at the same discount rate. Just verify it's significantly less than original per-drop.
    const origPpd = oils['椰子油'].bottlePrice / oils['椰子油'].dropCount
    expect(perDrop['椰子油']).toBeLessThan(origPpd)
    expect(perDrop['椰子油']).toBeGreaterThan(0)
  })

  it('accessoryValue reduces effective oil cost', () => {
    const kit = KITS.find(k => k.id === 'family')
    // Without accessory: rate = price / totalBp
    // With accessory: rate = price / (totalBp + accessoryValue) < previous rate
    expect(kit.accessoryValue).toBeGreaterThan(0)

    const bc = kit.bottleCount || {}
    let totalBp = 0
    for (const name of kit.oils) {
      const resolved = resolveOilName(name)
      const meta = oils[resolved]
      totalBp += meta ? meta.bottlePrice * (bc[resolved] || 1) : 0
    }
    const rateWithAcc = kit.price / (totalBp + kit.accessoryValue)
    const rateWithoutAcc = kit.price / totalBp
    expect(rateWithAcc).toBeLessThan(rateWithoutAcc)
  })
})

// ---------------------------------------------------------------------------
// Recipe Matching
// ---------------------------------------------------------------------------
describe('Recipe Matching', () => {
  it('larger kits can make at least as many recipes as smaller ones', () => {
    const counts = KITS.map(kit => {
      const matched = prodData.recipes.filter(r => canMakeRecipe(kit, r))
      return { id: kit.id, count: matched.length, oilCount: kit.oils.length }
    }).sort((a, b) => a.oilCount - b.oilCount)

    for (let i = 1; i < counts.length; i++) {
      expect(counts[i].count).toBeGreaterThanOrEqual(counts[i - 1].count)
    }
  })

  it('全精油 can make the most recipes', () => {
    const fullKit = KITS.find(k => k.id === 'full')
    const fullCount = prodData.recipes.filter(r => canMakeRecipe(fullKit, r)).length

    for (const kit of KITS) {
      if (kit.id === 'full') continue
      const count = prodData.recipes.filter(r => canMakeRecipe(kit, r)).length
      expect(fullCount).toBeGreaterThanOrEqual(count)
    }
  })

  it('灰指甲 (牛至+椰子油) can be made by 家庭医生', () => {
    const kit = KITS.find(k => k.id === 'family')
    const recipe = prodData.recipes.find(r => r.name === '灰指甲')
    expect(canMakeRecipe(kit, recipe)).toBe(true)
  })

  it('recipe requiring 永久花 cannot be made by 芳香调理', () => {
    const kit = KITS.find(k => k.id === 'aroma')
    const recipe = prodData.recipes.find(r => r.name === '小v脸') // has 永久花
    expect(canMakeRecipe(kit, recipe)).toBe(false)
  })
})

// ---------------------------------------------------------------------------
// Accessory Values — PR32
// ---------------------------------------------------------------------------
describe('Accessory Values', () => {
  it('芳香调理 has no accessories', () => {
    const kit = KITS.find(k => k.id === 'aroma')
    expect(kit.accessoryValue).toBeUndefined()
  })

  it('家庭医生 accessories = 475 (香薰机375 + 木盒100)', () => {
    const kit = KITS.find(k => k.id === 'family')
    expect(kit.accessoryValue).toBe(475)
  })

  it('居家呵护 accessories = 585 (香薰机375 + 竹木架210)', () => {
    const kit = KITS.find(k => k.id === 'home3988')
    expect(kit.accessoryValue).toBe(585)
  })

  it('全精油 accessories = 795 (香薰机375 + 竹木架210×2)', () => {
    const kit = KITS.find(k => k.id === 'full')
    expect(kit.accessoryValue).toBe(795)
  })
})

// ---------------------------------------------------------------------------
// Discount Rate Calculation — PR32
// ---------------------------------------------------------------------------
describe('Discount Rate', () => {
  function calcDiscountRate(kit) {
    const resolved = kit.oils.map(resolveOilName)
    const bc = kit.bottleCount || {}
    let totalBP = 0
    for (const name of resolved) {
      const meta = oils[name]
      totalBP += meta ? meta.bottlePrice * (bc[name] || 1) : 0
    }
    const totalValue = totalBP + (kit.accessoryValue || 0)
    return totalValue > 0 ? Math.min(kit.price / totalValue, 1) : 1
  }

  it('all kits have discount rate < 1 (套装比单买便宜)', () => {
    for (const kit of KITS) {
      const rate = calcDiscountRate(kit)
      expect(rate).toBeLessThan(1)
      expect(rate).toBeGreaterThan(0)
    }
  })

  it('全精油 discount rate ≈ 0.69', () => {
    const kit = KITS.find(k => k.id === 'full')
    const rate = calcDiscountRate(kit)
    expect(rate).toBeGreaterThan(0.65)
    expect(rate).toBeLessThan(0.75)
  })

  it('larger kits have better discounts', () => {
    const rates = KITS.map(k => ({ id: k.id, rate: calcDiscountRate(k), count: k.oils.length }))
    rates.sort((a, b) => a.count - b.count)
    // Generally larger kits should have lower discount rate (better deal)
    // At minimum, the largest kit should have a lower rate than the smallest
    expect(rates[rates.length - 1].rate).toBeLessThanOrEqual(rates[0].rate)
  })

  it('kit cost per recipe should be less than original cost', () => {
    for (const kit of KITS) {
      const perDrop = calcKitPerDrop(kit)
      const recipes = prodData.recipes.filter(r => canMakeRecipe(kit, r))
      for (const r of recipes.slice(0, 5)) {
        const kitCost = calcRecipeCostWithKit(perDrop, r)
        const originalCost = calcOriginalCost(r)
        expect(kitCost).toBeLessThanOrEqual(originalCost + 0.01)
      }
    }
  })
})