import { existsSync, readFileSync, rmSync, writeFileSync } from 'node:fs'
import { join } from 'node:path'

import { app, safeStorage } from 'electron/main'

export interface DesktopLoginCredentials {
  identifier: string
  password: string
}

interface PersistedLoginCredentials {
  version?: number
  identifier?: unknown
  encryptedPassword?: unknown
}

function credentialsPath(): string {
  return join(app.getPath('userData'), 'login-credentials.json')
}

function normalizeCredentials(input: unknown): PersistedLoginCredentials {
  if (!input || typeof input !== 'object') {
    return {}
  }
  return input as PersistedLoginCredentials
}

export function getSavedLoginCredentials(): DesktopLoginCredentials | null {
  try {
    if (!existsSync(credentialsPath())) {
      return null
    }

    const persisted = normalizeCredentials(JSON.parse(readFileSync(credentialsPath(), 'utf8')))
    const identifier = typeof persisted.identifier === 'string' ? persisted.identifier : ''
    const encryptedPassword =
      typeof persisted.encryptedPassword === 'string' ? persisted.encryptedPassword : ''

    if (!identifier || !encryptedPassword || !safeStorage.isEncryptionAvailable()) {
      return null
    }

    const password = safeStorage.decryptString(Buffer.from(encryptedPassword, 'base64'))
    return password ? { identifier, password } : null
  } catch (error) {
    console.warn('[login-credentials] read failed', {
      message: error instanceof Error ? error.message : String(error),
    })
    return null
  }
}

export function saveLoginCredentials(credentials: DesktopLoginCredentials): DesktopLoginCredentials {
  const identifier = credentials.identifier.trim()
  if (!identifier || !credentials.password) {
    clearSavedLoginCredentials()
    return { identifier: '', password: '' }
  }

  if (!safeStorage.isEncryptionAvailable()) {
    throw new Error('login_credentials_encryption_unavailable')
  }

  const encryptedPassword = safeStorage.encryptString(credentials.password).toString('base64')
  writeFileSync(
    credentialsPath(),
    JSON.stringify({
      version: 1,
      identifier,
      encryptedPassword,
      updatedAt: new Date().toISOString(),
    }),
    'utf8',
  )
  return { identifier, password: credentials.password }
}

export function clearSavedLoginCredentials(): null {
  try {
    rmSync(credentialsPath(), { force: true })
  } catch (error) {
    console.warn('[login-credentials] clear failed', {
      message: error instanceof Error ? error.message : String(error),
    })
  }
  return null
}