import { describe, it, expect } from 'vitest'
import type { VatDeclarationRutor } from '@/types'
import { runVatDeclarationChecks } from '../vat-declaration-checks'

const emptyRutor: VatDeclarationRutor = {
  ruta05: 0, ruta06: 0, ruta07: 0, ruta08: 0,
  ruta10: 0, ruta11: 0, ruta12: 0,
  ruta20: 0, ruta21: 0, ruta22: 0, ruta23: 0, ruta24: 0,
  ruta30: 0, ruta31: 0, ruta32: 0,
  ruta35: 0, ruta36: 0, ruta37: 0, ruta38: 0,
  ruta39: 0, ruta40: 0, ruta41: 0, ruta42: 0,
  ruta48: 0, ruta49: 0,
  ruta50: 0, ruta60: 0, ruta61: 0, ruta62: 0,
}

describe('runVatDeclarationChecks', () => {
  it('returns empty findings for a balanced sales-only declaration', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta05: 100000,
      ruta10: 25000,
      ruta49: 25000,
    }
    expect(runVatDeclarationChecks(rutor)).toEqual([])
  })

  it('returns empty findings for a balanced declaration with RC basis + output VAT', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta21: 10000, // EU services basis
      ruta30: 2500,  // RC output VAT
      ruta48: 2500,  // matching input VAT
      ruta49: 0,
    }
    expect(runVatDeclarationChecks(rutor)).toEqual([])
  })

  // FK004 mirror: SKV's primary rejection signal we want to catch locally.
  it('flags ERROR when ruta 30-32 populated but ruta 20-24 is empty', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta05: 78852,
      ruta10: 19713,
      ruta30: 2500,
      ruta48: 2500,
      ruta49: 19713,
    }
    const findings = runVatDeclarationChecks(rutor)
    const fk004 = findings.find((f) => f.code === 'RC_BASIS_MISSING')
    expect(fk004).toBeDefined()
    expect(fk004?.status).toBe('ERROR')
    expect(fk004?.message).toMatch(/ruta 30-32/)
    expect(fk004?.message).toMatch(/ruta 20-24/)
  })

  it('flags ERROR when basis is present but no output RC VAT', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta21: 10000,
      ruta48: 2500,
      ruta49: -2500,
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'RC_OUTPUT_MISSING')?.status).toBe('ERROR')
  })

  it('warns when input VAT is materially smaller than RC output VAT', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta21: 10000,
      ruta30: 2500,
      ruta48: 100, // Calculated input VAT missing — should be ~2500
      ruta49: 2400,
    }
    const findings = runVatDeclarationChecks(rutor)
    const mismatch = findings.find((f) => f.code === 'RC_INPUT_VAT_MISMATCH')
    expect(mismatch?.status).toBe('WARNING')
  })

  // FK009 detection: if our calculator and SKV's recomputed sum disagree
  // we flag locally so we never submit a drift.
  it('flags ERROR when ruta49 drifts from the canonical formula', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta10: 100,
      ruta48: 20,
      ruta49: 99, // wrong — should be 80
    }
    const findings = runVatDeclarationChecks(rutor)
    const drift = findings.find((f) => f.code === 'SUMMA_MOMS_DRIFT')
    expect(drift?.status).toBe('ERROR')
  })

  it('ignores fractional-öre drift (≤ 0.5 SEK)', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta10: 100.30,
      ruta48: 20.10,
      ruta49: 80.20, // canonical formula exactly, only fractional öre
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'SUMMA_MOMS_DRIFT')).toBeUndefined()
  })

  // SKV §4.1.1.4 rule 1 — taxable sales base without output VAT.
  it('flags ERROR when taxable sales (ruta 05) booked without output VAT', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta05: 10000,
      // ruta 10/11/12 all zero — SKV rule 1 violation
      ruta49: 0,
    }
    const findings = runVatDeclarationChecks(rutor)
    const finding = findings.find((f) => f.code === 'TAXABLE_SALES_WITHOUT_OUTPUT')
    expect(finding?.status).toBe('ERROR')
    expect(finding?.message).toMatch(/försäljning/)
    expect(finding?.message).toMatch(/utgående moms/)
  })

  it('flags ERROR for ruta 06 (uttag) without output VAT', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta06: 5000,
      ruta49: 0,
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'TAXABLE_SALES_WITHOUT_OUTPUT')?.status).toBe('ERROR')
  })

  it('does not flag taxable sales without output VAT when output VAT is present', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta05: 10000,
      ruta10: 2500,
      ruta49: 2500,
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'TAXABLE_SALES_WITHOUT_OUTPUT')).toBeUndefined()
  })

  // Mirror: output VAT without taxable sales base.
  it('flags ERROR when output VAT booked without taxable sales base', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      // No ruta 05/06/07/08
      ruta10: 2500,
      ruta49: 2500,
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'OUTPUT_VAT_WITHOUT_SALES_BASE')?.status).toBe('ERROR')
  })

  // SKV §4.1.1.4 rule 5 — import base without import output VAT.
  it('flags ERROR when import base (ruta 50) without import output VAT', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta50: 10000,
      // ruta 60/61/62 all zero
      ruta48: 0,
      ruta49: 0,
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'IMPORT_BASE_WITHOUT_OUTPUT')?.status).toBe('ERROR')
  })

  // SKV §4.1.1.4 rule 6 — import output VAT without import base.
  it('flags ERROR when import output VAT (ruta 60) without ruta 50', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta60: 2500,
      ruta48: 2500,
      ruta49: 0,
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'IMPORT_OUTPUT_WITHOUT_BASE')?.status).toBe('ERROR')
  })

  it('does not flag import checks when both base and output VAT are present', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta50: 10000,
      ruta60: 2500,
      ruta48: 2500,
      ruta49: 0,
    }
    const findings = runVatDeclarationChecks(rutor)
    expect(findings.find((f) => f.code === 'IMPORT_BASE_WITHOUT_OUTPUT')).toBeUndefined()
    expect(findings.find((f) => f.code === 'IMPORT_OUTPUT_WITHOUT_BASE')).toBeUndefined()
  })

  // Multiple findings should surface together so the user sees the whole picture.
  it('reports multiple distinct findings for a deeply broken declaration', () => {
    const rutor: VatDeclarationRutor = {
      ...emptyRutor,
      ruta05: 10000,    // taxable sales but no output VAT
      ruta30: 2500,     // RC output but no RC basis
      ruta50: 5000,     // import base but no import output
      ruta48: 0,
      ruta49: 2500,
    }
    const findings = runVatDeclarationChecks(rutor)
    const codes = findings.map((f) => f.code).sort()
    expect(codes).toContain('TAXABLE_SALES_WITHOUT_OUTPUT')
    expect(codes).toContain('RC_BASIS_MISSING')
    expect(codes).toContain('IMPORT_BASE_WITHOUT_OUTPUT')
  })
})