import { describe, it, expect } from 'vitest'
import { scanReducer, INITIAL_SCAN_STATE, type ScanState } from '../src/scan/reducer.js'
import type { Candidate, Item, ReleasePreview } from '../src/types.js'

const candidate: Candidate = {
  id: 1001,
  artist: 'The Cinematic Orchestra',
  title: 'Motion',
  year: 1999,
  formats: ['CD'],
  labels: ['Ninja Tune'],
  country: 'UK',
  catno: 'ZENCD012',
  thumbUrl: 'https://img/x.jpg',
}

const preview: ReleasePreview = {
  release: { ...candidate, genres: [], tracklist: [], coverUrl: null, barcodes: ['5021592210629'] },
  duplicate: false,
  ripMatch: 'not_ripped',
  matchCandidates: [],
}

const item: Item = {
  id: 1,
  discogsReleaseId: 1001,
  title: 'Motion',
  artist: 'The Cinematic Orchestra',
  year: 1999,
  formats: ['CD'],
  genres: [],
  labels: ['Ninja Tune'],
  tracklist: [],
  catno: 'ZENCD012',
  country: 'UK',
  artworkUrl: null,
  barcodes: ['5021592210629'],
  dateAdded: '2026-08-29',
  ripOverride: null,
  ripStatus: 'not_ripped',
}

function stateOf(phase: ScanState['phase']): ScanState {
  let state = INITIAL_SCAN_STATE
  const steps: Parameters<typeof scanReducer>[1][] = [
    { type: 'DETECT', code: '5021592210629' },
    { type: 'CANDIDATES', code: '5021592210629', candidates: [candidate] },
    { type: 'SELECT', candidate },
    { type: 'PREVIEW', preview },
    { type: 'ADD_START' },
    { type: 'ADDED', item },
  ]
  const order: ScanState['phase'][] = ['scan', 'looking', 'candidates', 'confirm', 'confirm', 'confirm', 'added']
  const idx = order.indexOf(phase)
  if (idx < 0) return state
  for (let i = 1; i <= idx; i++) state = scanReducer(state, steps[i - 1]!)
  return state
}

describe('scanReducer', () => {
  it('DETECT from scan → looking', () => {
    const next = scanReducer(INITIAL_SCAN_STATE, { type: 'DETECT', code: '123' })
    expect(next).toEqual({ phase: 'looking', code: '123' })
  })

  it('DETECT is ignored unless scanning (prevents duplicate lookups)', () => {
    const looking = stateOf('looking')
    expect(scanReducer(looking, { type: 'DETECT', code: '999' })).toBe(looking)
  })

  it('CANDIDATES from looking → candidates', () => {
    const next = scanReducer(stateOf('looking'), {
      type: 'CANDIDATES',
      code: '5021592210629',
      candidates: [candidate],
    })
    expect(next.phase).toBe('candidates')
  })

  it('NOT_FOUND from looking → error not_found', () => {
    const next = scanReducer(stateOf('looking'), { type: 'NOT_FOUND', code: '123' })
    expect(next).toEqual({ phase: 'error', kind: 'not_found', code: '123' })
  })

  it('ERROR maps kinds', () => {
    const next = scanReducer(stateOf('looking'), { type: 'ERROR', kind: 'no_discogs_token', code: '123' })
    expect(next).toEqual({ phase: 'error', kind: 'no_discogs_token', code: '123' })
  })

  it('SELECT from candidates → confirm with candidate, no preview yet', () => {
    const next = scanReducer(stateOf('candidates'), { type: 'SELECT', candidate })
    expect(next.phase).toBe('confirm')
    if (next.phase === 'confirm') {
      expect(next.candidate).toBe(candidate)
      expect(next.preview).toBeNull()
      expect(next.adding).toBe(false)
      expect(next.matchAlbumId).toBeNull()
    }
  })

  it('PREVIEW fills the confirm phase', () => {
    const next = scanReducer(stateOf('confirm'), { type: 'PREVIEW', preview })
    if (next.phase === 'confirm') expect(next.preview).toBe(preview)
    else throw new Error('expected confirm')
  })

  it('SET_MATCH / CLEAR_MATCH only in confirm', () => {
    const confirm = stateOf('confirm')
    const set = scanReducer(confirm, { type: 'SET_MATCH', albumId: 7 })
    if (set.phase === 'confirm') expect(set.matchAlbumId).toBe(7)
    const cleared = scanReducer(set, { type: 'CLEAR_MATCH' })
    if (cleared.phase === 'confirm') expect(cleared.matchAlbumId).toBeNull()
    expect(scanReducer(stateOf('scan'), { type: 'SET_MATCH', albumId: 7 })).toBe(stateOf('scan'))
  })

  it('ADD_START → ADDED', () => {
    const confirm = scanReducer(stateOf('confirm'), { type: 'PREVIEW', preview })
    const starting = scanReducer(confirm, { type: 'ADD_START' })
    if (starting.phase === 'confirm') expect(starting.adding).toBe(true)
    const added = scanReducer(starting, { type: 'ADDED', item })
    expect(added).toEqual({ phase: 'added', item })
  })

  it('ADD_ERROR stores the message without leaving confirm', () => {
    const confirm = scanReducer(stateOf('confirm'), { type: 'PREVIEW', preview })
    const starting = scanReducer(confirm, { type: 'ADD_START' })
    const next = scanReducer(starting, { type: 'ADD_ERROR', message: 'duplicate' })
    if (next.phase === 'confirm') {
      expect(next.adding).toBe(false)
      expect(next.addError).toBe('duplicate')
    } else {
      throw new Error('expected confirm')
    }
  })

  it('RESET returns to scan from anywhere', () => {
    for (const phase of ['looking', 'candidates', 'confirm', 'added', 'error'] as const) {
      expect(scanReducer(stateOf(phase), { type: 'RESET' })).toEqual({ phase: 'scan' })
    }
  })
})