import type { Candidate, Item, ReleasePreview } from '../types.js'

export type ScanErrorKind = 'not_found' | 'no_discogs_token' | 'rate_limited' | 'server'

export type ScanState =
  | { phase: 'scan' }
  | { phase: 'looking'; code: string }
  | { phase: 'candidates'; code: string; candidates: Candidate[] }
  | {
      phase: 'confirm'
      code: string | null
      candidate: Candidate
      preview: ReleasePreview | null
      matchAlbumId: number | null
      adding: boolean
      addError: string | null
    }
  | { phase: 'added'; item: Item }
  | { phase: 'error'; kind: ScanErrorKind; code: string | null }

export const INITIAL_SCAN_STATE: ScanState = { phase: 'scan' }

export type ScanAction =
  | { type: 'DETECT'; code: string }
  | { type: 'CANDIDATES'; code: string; candidates: Candidate[] }
  | { type: 'NOT_FOUND'; code: string }
  | { type: 'ERROR'; kind: ScanErrorKind; code: string | null }
  | { type: 'SELECT'; candidate: Candidate }
  | { type: 'PREVIEW'; preview: ReleasePreview }
  | { type: 'SET_MATCH'; albumId: number }
  | { type: 'CLEAR_MATCH' }
  | { type: 'ADD_START' }
  | { type: 'ADDED'; item: Item }
  | { type: 'ADD_ERROR'; message: string }
  | { type: 'RESET' }

export function scanReducer(state: ScanState, action: ScanAction): ScanState {
  switch (action.type) {
    case 'DETECT':
      return state.phase === 'scan' ? { phase: 'looking', code: action.code } : state
    case 'CANDIDATES':
      return state.phase === 'looking' ? { phase: 'candidates', code: action.code, candidates: action.candidates } : state
    case 'NOT_FOUND':
      return state.phase === 'looking' ? { phase: 'error', kind: 'not_found', code: action.code } : state
    case 'ERROR':
      return state.phase === 'looking' || state.phase === 'candidates' || state.phase === 'confirm'
        ? { phase: 'error', kind: action.kind, code: action.code }
        : state
    case 'SELECT':
      return state.phase === 'candidates'
        ? {
            phase: 'confirm',
            code: state.code,
            candidate: action.candidate,
            preview: null,
            matchAlbumId: null,
            adding: false,
            addError: null,
          }
        : state
    case 'PREVIEW':
      return state.phase === 'confirm' ? { ...state, preview: action.preview } : state
    case 'SET_MATCH':
      return state.phase === 'confirm' ? { ...state, matchAlbumId: action.albumId } : state
    case 'CLEAR_MATCH':
      return state.phase === 'confirm' ? { ...state, matchAlbumId: null } : state
    case 'ADD_START':
      return state.phase === 'confirm' && state.preview ? { ...state, adding: true, addError: null } : state
    case 'ADDED':
      return state.phase === 'confirm' ? { phase: 'added', item: action.item } : state
    case 'ADD_ERROR':
      return state.phase === 'confirm' ? { ...state, adding: false, addError: action.message } : state
    case 'RESET':
      return INITIAL_SCAN_STATE
  }
}