import { z } from 'zod'

export const CSP_REPORT_POLICY_VERSION = 'compat-v1'
export const CSP_REPORT_MAX_BYTES = 32 * 1024
export const CSP_REPORT_MAX_ITEMS = 20

const reportBodySchema = z.object({
  documentURL: z.string().optional(),
  documentUri: z.string().optional(),
  'document-uri': z.string().optional(),
  blockedURL: z.string().optional(),
  blockedUri: z.string().optional(),
  'blocked-uri': z.string().optional(),
  effectiveDirective: z.string().optional(),
  'effective-directive': z.string().optional(),
  violatedDirective: z.string().optional(),
  'violated-directive': z.string().optional()
}).passthrough()

const legacyReportSchema = z.object({
  'csp-report': reportBodySchema
}).passthrough()

const reportingApiReportSchema = z.object({
  type: z.string().optional(),
  body: reportBodySchema
}).passthrough()

const cspPayloadSchema = z.union([
  legacyReportSchema,
  reportingApiReportSchema,
  z.array(reportingApiReportSchema).min(1).max(CSP_REPORT_MAX_ITEMS)
])

/**
 * CSP 수집 API가 허용하는 JSON 계열 미디어 타입인지 확인한다.
 * @param {string} contentType - Content-Type 헤더
 * @returns {boolean} 허용 여부
 */
export const isSupportedCspReportContentType = (contentType) => {
  const mediaType = String(contentType || '').split(';', 1)[0].trim().toLowerCase()
  return mediaType === 'application/csp-report'
    || mediaType === 'application/reports+json'
    || mediaType === 'application/json'
    || (mediaType.startsWith('application/') && mediaType.endsWith('+json'))
}

/**
 * URL에서 쿼리와 fragment를 제외한 문서 경로만 추출한다.
 * @param {string} value - 문서 URL
 * @returns {string} 정규화된 문서 경로
 */
export const normalizeCspDocumentPath = (value) => {
  try {
    const url = new URL(String(value || ''), 'https://csp.invalid')
    const pathname = url.pathname
      .replace(/\/{2,}/g, '/')
      .slice(0, 512)
    return pathname.startsWith('/') ? pathname : '/'
  } catch {
    return '/'
  }
}

/**
 * 차단 URL에서 경로·쿼리·fragment를 제거하고 origin 수준으로 축약한다.
 * @param {string} value - 차단 URL
 * @returns {string} 차단 origin 또는 안전한 분류값
 */
export const normalizeCspBlockedOrigin = (value) => {
  const normalized = String(value || '').trim().toLowerCase()

  if (!normalized) {
    return 'unknown'
  }

  if (['inline', 'eval', 'self'].includes(normalized)) {
    return normalized
  }

  if (/^(data|blob|filesystem):/.test(normalized)) {
    return `${normalized.split(':', 1)[0]}:`
  }

  try {
    const url = new URL(normalized)
    return ['http:', 'https:'].includes(url.protocol)
      ? url.origin.slice(0, 255)
      : `${url.protocol}`.slice(0, 32)
  } catch {
    return 'unknown'
  }
}

/**
 * User-Agent 원문을 저장하지 않도록 브라우저 계열로 축약한다.
 * @param {string} userAgent - User-Agent 헤더
 * @returns {string} 브라우저 계열
 */
export const classifyCspUserAgentFamily = (userAgent) => {
  const value = String(userAgent || '')

  if (/Edg\//i.test(value)) {
    return 'Edge'
  }
  if (/Firefox\//i.test(value)) {
    return 'Firefox'
  }
  if (/Chrome\//i.test(value) || /Chromium\//i.test(value)) {
    return 'Chrome'
  }
  if (/Safari\//i.test(value) && /Version\//i.test(value)) {
    return 'Safari'
  }

  return 'Other'
}

/**
 * 지시어 이름을 집계 키로 사용할 수 있는 짧은 값으로 정규화한다.
 * @param {string} value - CSP 지시어
 * @returns {string} 정규화된 지시어
 */
const normalizeDirective = (value) => {
  const directive = String(value || '').trim().toLowerCase().split(/\s+/, 1)[0]
  return /^[a-z][a-z0-9-]{0,63}$/.test(directive) ? directive : 'unknown'
}

/**
 * CSP 보고 payload를 검증하고 개인정보가 최소화된 집계 행으로 변환한다.
 * @param {unknown} payload - JSON payload
 * @param {string} userAgent - User-Agent 헤더
 * @returns {Array<{ policyVersion: string, documentPath: string, effectiveDirective: string, blockedOrigin: string, userAgentFamily: string }>} 집계 행 목록
 */
export const parseCspReportPayload = (payload, userAgent) => {
  const parsed = cspPayloadSchema.safeParse(payload)
  if (!parsed.success) {
    throw new Error('INVALID_CSP_REPORT')
  }

  const reports = Array.isArray(parsed.data) ? parsed.data : [parsed.data]
  return reports.map((report) => {
    const body = 'csp-report' in report ? report['csp-report'] : report.body
    const documentUrl = body.documentURL || body.documentUri || body['document-uri'] || ''
    const blockedUrl = body.blockedURL || body.blockedUri || body['blocked-uri'] || ''
    const directive = body.effectiveDirective
      || body['effective-directive']
      || body.violatedDirective
      || body['violated-directive']
      || ''

    return {
      policyVersion: CSP_REPORT_POLICY_VERSION,
      documentPath: normalizeCspDocumentPath(documentUrl),
      effectiveDirective: normalizeDirective(directive),
      blockedOrigin: normalizeCspBlockedOrigin(blockedUrl),
      userAgentFamily: classifyCspUserAgentFamily(userAgent)
    }
  })
}