/**
 * split-component-registry — lossless monolith → per-module migration.
 *
 * Pins the zero-loss contract: statements carried VERBATIM (meta 3rd arg
 * included), fail-closed on anything unattributable (key without 2 segments,
 * unknown top-level statement, phantom import, existing per-module target),
 * idempotent no-op on an already-migrated aggregate, and the full pipeline
 * (split plan → write → in-process re-aggregation with
 * overwriteLegacyAggregate) leaving a clean per-module layout.
 */
import { describe, it, expect, beforeEach, afterEach } from 'vitest'
import fs from 'node:fs'
import os from 'node:os'
import path from 'node:path'
import { generate } from '../generate.js'
import { generate as aggregateGenerate } from '../../aggregate-component-registry/generate.js'
import { writeGeneratedFilesAtomic } from '../../aggregate-component-registry/write.js'
import { buildRegistryIndex } from '../../../../../../lib/registry-index.js'
import type { SplitComponentRegistryInput } from '../types.js'

let web: string

beforeEach(() => {
  web = fs.mkdtempSync(path.join(os.tmpdir(), 'split-'))
})

afterEach(() => {
  fs.rmSync(web, { recursive: true, force: true })
})

function write(rel: string, content: string): void {
  const abs = path.join(web, rel)
  fs.mkdirSync(path.dirname(abs), { recursive: true })
  fs.writeFileSync(abs, content)
}

function spec(overrides: Partial<SplitComponentRegistryInput> = {}): SplitComponentRegistryInput {
  return {
    projectPath: web,
    registryFile: 'src/extensions/componentRegistry.generated.ts',
    dry_run: false,
    backup: true,
    aggregate: true,
    ...overrides,
  }
}

const MONOLITH = `// ============================================================================
// componentRegistry.generated.ts — Auto-generated by SmartStack MCP
// ============================================================================
import { lazy } from 'react';
import { PageRegistry, lazyWithRetry } from '@atlashub/smartstack';

// Fleet
PageRegistry.register('fleet.bikes', lazy(() => import('@/pages/fleet/bikes/FleetBikeListPage')));
PageRegistry.register('fleet.bikes.detail', lazy(() => import('@/pages/fleet/bikes/FleetBikeDetailPage')), {
  mobile: { support: 'adapted', offlineCapable: true },
});
const StationsPage = lazyWithRetry(() => import('@/pages/fleet/stations/StationsPage').then((m) => ({ default: m.StationsPage })));
PageRegistry.register('fleet.stations', StationsPage);
// Billing
PageRegistry.register('billing.invoices', lazy(() => import('@/pages/billing/invoices/InvoicesListPage')));
`

function writeMonolithPages(): void {
  write('src/pages/fleet/bikes/FleetBikeListPage.tsx', 'export default () => null\n')
  write('src/pages/fleet/bikes/FleetBikeDetailPage.tsx', 'export default () => null\n')
  write('src/pages/fleet/stations/StationsPage.tsx', 'export const StationsPage = () => null\n')
  write('src/pages/billing/invoices/InvoicesListPage.tsx', 'export default () => null\n')
}

describe('split-component-registry — nominal split', () => {
  it('splits the monolith into per-module files, statements verbatim, keys complete', () => {
    write('src/extensions/componentRegistry.generated.ts', MONOLITH)
    writeMonolithPages()

    const plan = generate(spec())
    expect(plan.errors).toEqual([])
    expect(plan.noop).toBe(false)
    expect(plan.keysMigrated).toBe(4)
    expect(plan.moduleFiles.map((f) => f.moduleId).sort()).toEqual(['billing-invoices', 'fleet-bikes', 'fleet-stations'])

    const bikes = plan.moduleFiles.find((f) => f.moduleId === 'fleet-bikes')!
    expect(bikes.path).toBe('src/extensions/fleet-bikesRegistry.ts')
    expect(bikes.keys).toEqual(['fleet.bikes', 'fleet.bikes.detail'])
    // statements verbatim — inline lazy + the meta 3rd argument survive byte-for-byte
    expect(bikes.content).toContain("PageRegistry.register('fleet.bikes', lazy(() => import('@/pages/fleet/bikes/FleetBikeListPage')));")
    expect(bikes.content).toContain("mobile: { support: 'adapted', offlineCapable: true }")
    // only the imports the statements need
    expect(bikes.content).toContain("import { lazy } from 'react';")
    expect(bikes.content).toContain("import { PageRegistry, lazyWithRetry } from '@atlashub/smartstack';")

    const stations = plan.moduleFiles.find((f) => f.moduleId === 'fleet-stations')!
    // the const binding travels with its registration, .then continuation intact
    expect(stations.content).toContain('const StationsPage = lazyWithRetry(() =>')
    expect(stations.content).toContain('.then((m) => ({ default: m.StationsPage }))')
    expect(stations.content).toContain("PageRegistry.register('fleet.stations', StationsPage);")
  })

  it('full pipeline: write the split then re-aggregate with overwriteLegacyAggregate → clean per-module layout', () => {
    write('src/extensions/componentRegistry.generated.ts', MONOLITH)
    writeMonolithPages()

    const plan = generate(spec())
    expect(plan.errors).toEqual([])
    writeGeneratedFilesAtomic(web, plan.moduleFiles.map((f) => ({ path: f.path, content: f.content })))

    // the guard fires without the escape hatch (monolith still on disk)
    const refused = aggregateGenerate({ projectPath: web, exclude: [] })
    expect(refused.errors[0]).toContain('registry.mixed-layout')

    const agg = aggregateGenerate({ projectPath: web, exclude: [], overwriteLegacyAggregate: true })
    expect(agg.errors).toEqual([])
    expect(agg.unresolved).toEqual([])
    expect(agg.collisions).toEqual([])
    writeGeneratedFilesAtomic(web, agg.files)

    const index = buildRegistryIndex(web)
    expect(index.layout).toBe('per-module')
    expect([...index.byKey.keys()].sort()).toEqual(['billing.invoices', 'fleet.bikes', 'fleet.bikes.detail', 'fleet.stations'])
  })

  it('idempotence: a clean aggregate (already migrated) is a no-op', () => {
    write('src/extensions/componentRegistry.generated.ts', `import './fleet-bikesRegistry';\n`)
    const plan = generate(spec())
    expect(plan.noop).toBe(true)
    expect(plan.errors).toEqual([])
    expect(plan.moduleFiles).toEqual([])
  })
})

describe('split-component-registry — fail-closed', () => {
  it('a key with fewer than 2 dotted segments aborts with zero module files', () => {
    write(
      'src/extensions/componentRegistry.generated.ts',
      `import { lazy } from 'react';
import { PageRegistry } from '@atlashub/smartstack';
PageRegistry.register('dashboard', lazy(() => import('@/pages/Dashboard')));
`,
    )
    write('src/pages/Dashboard.tsx', 'export default () => null\n')
    const plan = generate(spec())
    expect(plan.errors).toHaveLength(1)
    expect(plan.errors[0]).toContain("Cannot attribute componentKey 'dashboard'")
    expect(plan.moduleFiles).toEqual([])
  })

  it('an unknown top-level statement aborts; a moduleResources side-effect import is dropped with a warning', () => {
    write(
      'src/extensions/componentRegistry.generated.ts',
      `import { lazy } from 'react';
import { PageRegistry } from '@atlashub/smartstack';
import './moduleResources.generated';
i18next.init({ lng: 'fr' });
PageRegistry.register('fleet.bikes', lazy(() => import('@/pages/fleet/bikes/FleetBikeListPage')));
`,
    )
    write('src/pages/fleet/bikes/FleetBikeListPage.tsx', 'export default () => null\n')
    const plan = generate(spec())
    expect(plan.errors.some((e) => e.includes('Unmigratable top-level statement') && e.includes('i18next.init'))).toBe(true)
    expect(plan.moduleFiles).toEqual([])
    expect(plan.droppedSideEffects).toEqual(['./moduleResources.generated'])
    expect(plan.warnings.some((w) => w.includes('moduleResources'))).toBe(true)
  })

  it('a phantom import aborts BEFORE any write is planned', () => {
    write(
      'src/extensions/componentRegistry.generated.ts',
      `import { lazy } from 'react';
import { PageRegistry } from '@atlashub/smartstack';
PageRegistry.register('fleet.bikes', lazy(() => import('@/pages/fleet/bikes/DeletedPage')));
`,
    )
    const plan = generate(spec())
    expect(plan.errors).toHaveLength(1)
    expect(plan.errors[0]).toContain('ALREADY dead')
    expect(plan.moduleFiles).toEqual([])
  })

  it('an untraceable component reference aborts', () => {
    write(
      'src/extensions/componentRegistry.generated.ts',
      `import { PageRegistry } from '@atlashub/smartstack';
PageRegistry.register('fleet.bikes', MysteryPage);
`,
    )
    const plan = generate(spec())
    expect(plan.errors).toHaveLength(1)
    expect(plan.errors[0]).toContain('provenance')
    expect(plan.moduleFiles).toEqual([])
  })

  it('appCode control: a stray app segment aborts', () => {
    write(
      'src/extensions/componentRegistry.generated.ts',
      `import { lazy } from 'react';
import { PageRegistry } from '@atlashub/smartstack';
PageRegistry.register('billing.invoices', lazy(() => import('@/pages/billing/invoices/InvoicesListPage')));
`,
    )
    write('src/pages/billing/invoices/InvoicesListPage.tsx', 'export default () => null\n')
    const plan = generate(spec({ appCode: 'fleet' }))
    expect(plan.errors).toHaveLength(1)
    expect(plan.errors[0]).toContain("app segment 'billing'")
  })
})

describe('split-component-registry — mixed layout reconciliation', () => {
  const PER_MODULE = `import { PageRegistry, lazyWithRetry } from '@atlashub/smartstack';
const B = lazyWithRetry(() => import('@/pages/fleet/bikes/BikesListPage'));
PageRegistry.register('fleet.bikes', B);
`

  it('a monolith key an existing per-module registry owns is dropped with a warning', () => {
    write(
      'src/extensions/componentRegistry.generated.ts',
      `import { lazy } from 'react';
import { PageRegistry } from '@atlashub/smartstack';
PageRegistry.register('fleet.bikes', lazy(() => import('@/pages/fleet/bikes/FleetBikeListPage')));
PageRegistry.register('billing.invoices', lazy(() => import('@/pages/billing/invoices/InvoicesListPage')));
`,
    )
    write('src/extensions/fleet-bikesRegistry.ts', PER_MODULE)
    write('src/pages/fleet/bikes/BikesListPage.tsx', 'export default () => null\n')
    write('src/pages/fleet/bikes/FleetBikeListPage.tsx', 'export default () => null\n')
    write('src/pages/billing/invoices/InvoicesListPage.tsx', 'export default () => null\n')

    const plan = generate(spec())
    expect(plan.errors).toEqual([])
    expect(plan.droppedDuplicates).toEqual(['fleet.bikes'])
    expect(plan.warnings.some((w) => w.includes('already owned by'))).toBe(true)
    expect(plan.moduleFiles.map((f) => f.moduleId)).toEqual(['billing-invoices'])
  })

  it('remaining keys targeting a module whose file already exists → hard error (never merge)', () => {
    write(
      'src/extensions/componentRegistry.generated.ts',
      `import { lazy } from 'react';
import { PageRegistry } from '@atlashub/smartstack';
PageRegistry.register('fleet.bikes.detail', lazy(() => import('@/pages/fleet/bikes/FleetBikeDetailPage')));
`,
    )
    write('src/extensions/fleet-bikesRegistry.ts', PER_MODULE)
    write('src/pages/fleet/bikes/BikesListPage.tsx', 'export default () => null\n')
    write('src/pages/fleet/bikes/FleetBikeDetailPage.tsx', 'export default () => null\n')

    const plan = generate(spec())
    expect(plan.errors).toHaveLength(1)
    expect(plan.errors[0]).toContain('refusing to merge')
    expect(plan.moduleFiles).toEqual([])
  })
})