import { useState, useCallback } from 'react'

export interface TokenEntry {
  id: string
  token: string
  label: string
}

const TOKENS_KEY = 'rcs_tokens'
const ACTIVE_TOKEN_KEY = 'rcs_uuid'
const DEFAULT_ID = '__default__'

function generateId(): string {
  return `tk_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 8)}`
}

/** Ensure the existing rcs_uuid is present as the default token entry */
function ensureDefault(tokens: TokenEntry[]): TokenEntry[] {
  if (tokens.some(t => t.id === DEFAULT_ID)) return tokens
  let uuid: string | null = null
  try {
    uuid = localStorage.getItem('rcs_uuid')
  } catch {
    // ignore
  }
  if (!uuid) return tokens
  return [{ id: DEFAULT_ID, token: uuid, label: 'Default' }, ...tokens]
}

function loadTokens(): TokenEntry[] {
  let tokens: TokenEntry[] = []
  try {
    const raw = localStorage.getItem(TOKENS_KEY)
    if (raw) {
      const parsed = JSON.parse(raw)
      if (Array.isArray(parsed)) tokens = parsed
    }
  } catch {
    // ignore
  }
  return ensureDefault(tokens)
}

function loadActiveTokenId(tokens: TokenEntry[]): string {
  // Try saved active token
  try {
    const saved = localStorage.getItem(ACTIVE_TOKEN_KEY)
    if (saved && tokens.some(t => t.id === saved)) return saved
  } catch {
    // ignore
  }
  // Fall back to default (rcs_uuid) entry
  const defaultEntry = tokens.find(t => t.id === DEFAULT_ID)
  if (defaultEntry) return defaultEntry.id
  // Fall back to first entry
  return tokens[0]?.id ?? DEFAULT_ID
}

export function useTokens() {
  const [tokens, setTokens] = useState<TokenEntry[]>(loadTokens)
  const [activeTokenId, setActiveTokenIdState] = useState<string>(() =>
    loadActiveTokenId(loadTokens()),
  )

  const persistTokens = useCallback((next: TokenEntry[]) => {
    setTokens(next)
    try {
      localStorage.setItem(TOKENS_KEY, JSON.stringify(next))
    } catch {
      // ignore
    }
  }, [])

  const setActiveTokenId = useCallback((id: string) => {
    setActiveTokenIdState(id)
    try {
      localStorage.setItem(ACTIVE_TOKEN_KEY, id)
      location.reload() // Reload to ensure api client picks up new token from localStorage
    } catch {
      // ignore
    }
  }, [])

  const addToken = useCallback(
    (token: string, label: string): string | null => {
      const trimmed = token.trim()
      if (!trimmed) return 'Token is required'
      const entry: TokenEntry = {
        id: generateId(),
        token: trimmed,
        label: label.trim() || trimmed.slice(0, 8),
      }
      const next = [...tokens, entry]
      persistTokens(next)
      return null
    },
    [tokens, persistTokens],
  )

  const removeToken = useCallback(
    (id: string) => {
      if (id === DEFAULT_ID) return // Cannot remove default
      const next = tokens.filter(t => t.id !== id)
      persistTokens(next)
      if (activeTokenId === id) {
        setActiveTokenId(DEFAULT_ID)
      }
    },
    [tokens, persistTokens, activeTokenId, setActiveTokenId],
  )

  const updateToken = useCallback(
    (id: string, label: string) => {
      const next = tokens.map(t => (t.id === id ? { ...t, label } : t))
      persistTokens(next)
    },
    [tokens, persistTokens],
  )

  const activeToken =
    tokens.find(t => t.id === activeTokenId) ?? tokens[0] ?? null
  const activeLabel = activeToken?.label ?? 'Default'
  const activeTokenValue = activeToken?.token ?? null

  return {
    tokens,
    activeTokenId,
    activeToken,
    activeLabel,
    activeTokenValue,
    setActiveTokenId,
    addToken,
    removeToken,
    updateToken,
  }
}