export interface EditableAccountProfile {
  realName: string
  email: string
}

export interface LoginIdentifierChangePayload {
  username: string
  phone: string
  currentPassword: string
}

export interface PasswordChangePayload {
  currentPassword: string
  newPassword: string
  confirmPassword: string
}

const EMAIL_PATTERN = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
const USERNAME_PATTERN = /^[A-Za-z][A-Za-z0-9_.@-]{3,63}$/
const MAINLAND_MOBILE_PATTERN = /^1[3-9]\d{9}$/

export function validateEditableAccountProfile(profile: EditableAccountProfile): string[] {
  const errors: string[] = []
  const realName = profile.realName.trim()
  const email = profile.email.trim()

  if (realName.length < 1 || realName.length > 64) errors.push('姓名需为 1–64 个字符')
  if (email && !EMAIL_PATTERN.test(email)) errors.push('请输入有效的邮箱地址')

  return errors
}

export function validateLoginIdentifierChange(payload: LoginIdentifierChangePayload): string[] {
  const errors: string[] = []
  if (!USERNAME_PATTERN.test(payload.username.trim())) {
    errors.push('用户名须以字母开头，并由 4–64 位字母、数字或 _.@- 组成')
  }
  if (!MAINLAND_MOBILE_PATTERN.test(payload.phone.trim())) errors.push('请输入有效的中国大陆手机号')
  if (!payload.currentPassword) errors.push('请输入当前密码')
  return errors
}

export function validatePasswordChange(payload: PasswordChangePayload): string[] {
  const errors: string[] = []

  if (!payload.currentPassword) errors.push('请输入当前密码')
  if (payload.newPassword.length < 8 || payload.newPassword.length > 64) {
    errors.push('新密码需为 8–64 个字符')
  }
  if (payload.newPassword.length >= 8 && (!/[a-zA-Z]/.test(payload.newPassword) || !/\d/.test(payload.newPassword))) {
    errors.push('新密码必须同时包含字母和数字')
  }
  if (payload.newPassword && payload.newPassword === payload.currentPassword) {
    errors.push('新密码不能与当前密码相同')
  }
  if (payload.confirmPassword !== payload.newPassword) errors.push('两次输入的新密码不一致')

  return errors
}

export type PasswordStrength = 'weak' | 'medium' | 'strong'

export function getPasswordStrength(password: string): PasswordStrength {
  let categoryCount = 0
  if (/[a-zA-Z]/.test(password)) categoryCount += 1
  if (/\d/.test(password)) categoryCount += 1
  if (/[^a-zA-Z\d]/.test(password)) categoryCount += 1

  if (password.length >= 12 && categoryCount >= 3) return 'strong'
  if (password.length >= 8 && categoryCount >= 2) return 'medium'
  return 'weak'
}