import { describe, it } from 'node:test'
import assert from 'node:assert'
import {
  getTotalBudget,
  getTotalSpent,
  getRemaining,
  getProgressPercent,
  addTransaction,
  removeTransaction,
  rollOverMonth,
  computeLifestyleCreep,
  getNetWorth,
} from '../src/lib/budget.js'
import type { Category, Transaction } from '../src/types.js'

const baseCats: Category[] = [
  { id: 'food', name: 'Food', budget: 500, spent: 100, color: '#4CAF50', isSinkingFund: false, rolloverEnabled: false, rolloverAmount: 0 },
  { id: 'vacation', name: 'Vacation', budget: 200, spent: 0, color: '#00BCD4', isSinkingFund: true, rolloverEnabled: true, rolloverAmount: 50 },
]

describe('getTotalBudget', () => {
  it('sums category budgets including rollover', () => {
    assert.strictEqual(getTotalBudget(baseCats), 750)
  })
})

describe('getTotalSpent', () => {
  it('sums category spending', () => {
    assert.strictEqual(getTotalSpent(baseCats), 100)
  })
})

describe('getRemaining', () => {
  it('computes remaining for non-sinking fund', () => {
    assert.strictEqual(getRemaining(baseCats[0]), 400)
  })
  it('includes rollover for sinking fund', () => {
    assert.strictEqual(getRemaining(baseCats[1]), 250)
  })
})

describe('getProgressPercent', () => {
  it('returns correct percent', () => {
    assert.strictEqual(getProgressPercent(baseCats[0]), 20)
  })
  it('caps at 100', () => {
    const cat: Category = { ...baseCats[0], spent: 600 }
    assert.strictEqual(getProgressPercent(cat), 100)
  })
})

describe('addTransaction', () => {
  it('adds a simple transaction', () => {
    const tx: Transaction = { id: '1', date: '2024-01-01', amount: 50, merchant: 'Store', categoryId: 'food', description: '', isSplit: false }
    const result = addTransaction(baseCats, [], tx)
    assert.strictEqual(result.categories[0].spent, 150)
    assert.strictEqual(result.transactions.length, 1)
  })
  it('adds a split transaction', () => {
    const tx: Transaction = {
      id: '2', date: '2024-01-01', amount: 100, merchant: 'Amazon', categoryId: 'food', description: '', isSplit: true,
      items: [{ name: 'Food', amount: 60, categoryId: 'food' }, { name: 'Thing', amount: 40, categoryId: 'vacation' }],
      originalAmount: 100,
    }
    const result = addTransaction(baseCats, [], tx)
    assert.strictEqual(result.categories[0].spent, 160)
    assert.strictEqual(result.categories[1].spent, 40)
  })
})

describe('removeTransaction', () => {
  it('removes a transaction and reverts spending', () => {
    const tx: Transaction = { id: '1', date: '2024-01-01', amount: 50, merchant: 'Store', categoryId: 'food', description: '', isSplit: false }
    const added = addTransaction(baseCats, [], tx)
    const result = removeTransaction(added.categories, added.transactions, '1')
    assert.strictEqual(result.categories[0].spent, 100)
    assert.strictEqual(result.transactions.length, 0)
  })
})

describe('rollOverMonth', () => {
  it('rolls over remaining to next month for sinking funds', () => {
    const cats = rollOverMonth(baseCats)
    assert.strictEqual(cats[1].rolloverAmount, 300)
    assert.strictEqual(cats[1].spent, 0)
  })
  it('does not roll over non-sinking funds', () => {
    const cats = rollOverMonth(baseCats)
    assert.strictEqual(cats[0].rolloverAmount, 0)
    assert.strictEqual(cats[0].spent, 0)
  })
})

describe('computeLifestyleCreep', () => {
  it('computes year-over-year changes', () => {
    const snapshots = [
      { month: '2023-06', categories: { food: { budget: 400, spent: 300 } }, netWorth: 10000 },
      { month: '2024-06', categories: { food: { budget: 500, spent: 350 } }, netWorth: 12000 },
    ]
    const creep = computeLifestyleCreep(snapshots, '2024-06')
    assert.strictEqual(creep.length, 1)
    assert.strictEqual(creep[0].changePercent, 25)
    assert.strictEqual(creep[0].isInflation, true)
  })
})

describe('getNetWorth', () => {
  it('sums all account balances', () => {
    const accounts = [{ id: '1', name: 'A', type: 'checking' as const, balance: 1000 }, { id: '2', name: 'B', type: 'savings' as const, balance: 2000 }]
    assert.strictEqual(getNetWorth(accounts), 3000)
  })
})