/**
 * derived-field.test.ts — the « colonne dérivée » engine (§ the fil rouge):
 * a read member whose value lives behind a navigation or inside a dated
 * child. The four client workarounds it closes: PlateNumber (open
 * registration), CurrentMileage (latest reading), OfficeName (open site
 * assignment), Email (User navigation).
 */
import { describe, it, expect } from 'vitest'
import { generate } from '../generate.js'
import { validate } from '../validate.js'
import { ScaffoldBusinessInputSchema, type ScaffoldBusinessInput } from '../types.js'

function spec(fields: object[]): ScaffoldBusinessInput {
  return ScaffoldBusinessInputSchema.parse({
    name: 'Vehicle',
    pluralName: 'Vehicles',
    module: 'parc',
    appCode: 'Demo',
    applicationCode: 'flotte',
    namespace: 'Demo',
    // Display is not this suite's subject — Vehicle has no Name-family column
    // (its identity is the derived plate), so opt out consciously (§26: the
    // silent first-string/GUID fallback is gone).
    displayNameExpr: 'Id',
    fields,
    businessRules: [],
    customActions: [],
    projectPath: '/tmp/project',
  })
}

const svcOf = (s: ScaffoldBusinessInput) =>
  generate(s).find(f => f.path.endsWith('/VehicleService.cs'))!.content
const dtoOf = (s: ScaffoldBusinessInput) =>
  generate(s).find(f => /DTOs\/.*\.cs$/.test(f.path))!.content

describe('scaffold-business / derived fields — the fil-rouge projections', () => {
  it('child open-period: the open registration plate projects EF-translatably, nullable', () => {
    const s = spec([
      { name: 'Vin', type: 'string', required: true },
      { name: 'PlateNumber', type: 'string', required: false, derived: { kind: 'child', collection: 'Registrations', select: 'PlateNumber', pick: { mode: 'open-period', endField: 'EndDate' } } },
    ])
    const svc = svcOf(s)
    expect(svc).toContain('x.Registrations.Where(c => c.EndDate == null).Select(c => c.PlateNumber).FirstOrDefault()')
    // Read surfaces carry it; write surfaces never do.
    const dto = dtoOf(s)
    expect(dto).toMatch(/record VehicleListDto\([\s\S]*?string\? PlateNumber,/)
    expect(dto).not.toMatch(/record CreateVehicleDto\([\s\S]*?PlateNumber/)
    expect(dto).not.toMatch(/record UpdateVehicleDto\([\s\S]*?PlateNumber/)
  })

  it('child latest: the last odometer reading projects with a nullable value-type cast', () => {
    const s = spec([
      { name: 'Vin', type: 'string', required: true },
      { name: 'CurrentMileage', type: 'int', required: false, derived: { kind: 'child', collection: 'OdometerReadings', select: 'Mileage', pick: { mode: 'latest', dateField: 'ReadingDate' } } },
    ])
    expect(svcOf(s)).toContain('x.OdometerReadings.OrderByDescending(c => c.ReadingDate).Select(c => (int?)c.Mileage).FirstOrDefault()')
    expect(dtoOf(s)).toMatch(/int\? CurrentMileage,/)
  })

  it('nav: a nullable-FK hop guards the read (the Email-from-User shape)', () => {
    const s = spec([
      { name: 'UserId', type: 'guid', required: false },
      { name: 'Email', type: 'string', required: false, derived: { kind: 'nav', nav: 'User', property: 'Email' } },
    ])
    expect(svcOf(s)).toContain('(x.UserId != null ? x.User!.Email : null)')
  })

  it('nav: a required FK reads straight through', () => {
    const s = spec([
      { name: 'OfficeId', type: 'guid', required: true },
      { name: 'OfficeName', type: 'string', required: false, derived: { kind: 'nav', nav: 'Office', property: 'Name' } },
    ])
    expect(svcOf(s)).toContain('x.Office.Name')
  })

  it('a derived member is never searchable nor a sort arm (v1 boundary)', () => {
    const s = spec([
      { name: 'Vin', type: 'string', required: true },
      { name: 'PlateNumber', type: 'string', required: false, derived: { kind: 'child', collection: 'Registrations', select: 'PlateNumber', pick: { mode: 'open-period', endField: 'EndDate' } } },
    ])
    const svc = svcOf(s)
    const searchIdx = svc.indexOf('EF.Functions.Like(x.Vin')
    expect(searchIdx).toBeGreaterThan(-1)
    expect(svc).not.toContain('EF.Functions.Like(x.Registrations')
    expect(svc).not.toContain('"platenumber" => ')
  })

  it('validate: derived × formula/source is refused, and derived + required too', () => {
    const both = validate({
      ...spec([{ name: 'Vin', type: 'string', required: true }]),
      fields: [{ name: 'X', type: 'string', required: false, formula: 'Vin', derived: { kind: 'nav', nav: 'User', property: 'Email' } }],
    })
    expect(both.valid).toBe(false)
    expect(both.errors.some(e => /mutually exclusive/.test(e))).toBe(true)
    const req = validate({
      ...spec([{ name: 'Vin', type: 'string', required: true }]),
      fields: [{ name: 'X', type: 'string', required: true, derived: { kind: 'nav', nav: 'User', property: 'Email' } }],
    })
    expect(req.valid).toBe(false)
    expect(req.errors.some(e => /cannot be required/.test(e))).toBe(true)
  })
})