import axios from 'axios'

import { unwrapApiResponse } from '@/utils/api-response'
import { mockFlags } from '@/utils/mock-flags'
import { request } from '@/utils/request'

import { getMockSigningTask } from './signing'
import type {
  ApiPageResponse,
  ApiResponseOf,
  SignArtifactResponseDto,
  SignArtifactType,
  SigningArtifact,
} from './types'

const useMockData = mockFlags.signing

type ArtifactCollection = SignArtifactResponseDto[] | ApiPageResponse<SignArtifactResponseDto>

const artifactLabels: Record<string, string> = {
  ORIGINAL_PDF: 'PDF 原件',
  SIGNATURE_IMAGE: '签名原图',
  SIGNED_PDF: '签署后 PDF',
}

function formatDateTime(value: string | null | undefined) {
  if (!value) {
    return ''
  }

  const date = new Date(value)

  if (Number.isNaN(date.getTime())) {
    return value
      .replace('T', ' ')
      .replace(/\.\d+Z$/, '')
      .replace(/Z$/, '')
  }

  const pad = (part: number) => String(part).padStart(2, '0')
  return `${date.getFullYear()}-${pad(date.getMonth() + 1)}-${pad(date.getDate())} ${pad(
    date.getHours(),
  )}:${pad(date.getMinutes())}`
}

function getCollectionRecords(collection: ArtifactCollection) {
  return Array.isArray(collection) ? collection : collection.records
}

function normalizeArtifact(dto: SignArtifactResponseDto): SigningArtifact {
  const artifactType: SignArtifactType = dto.artifactType
  const label = artifactLabels[artifactType] ?? '签署文件'
  const mimeType = dto.mimeType || 'application/octet-stream'
  const extension =
    mimeType === 'application/pdf' ? 'pdf' : mimeType === 'image/png' ? 'png' : 'bin'

  return {
    id: dto.id,
    taskId: dto.taskId,
    pipelineId: dto.pipelineId,
    artifactType,
    label,
    fileName: `${label}.${extension}`,
    mimeType,
    sizeBytes: dto.sizeBytes,
    sha256: dto.sha256,
    metadata: dto.metadata ?? {},
    createdAt: formatDateTime(dto.createdAt),
  }
}

export const isArtifactMockEnabled = useMockData

/**
 * 演示签名原图产物的 id 前缀。
 * 演示环境没有文件服务，下载时靠 id 反查任务里的签名图，
 * 保证「签名原图」在演示里也是真能下载到的文件，而不是占位提示。
 */
const MOCK_SIGNATURE_PREFIX = 'mock-signature-'

function estimateDataUrlBytes(dataUrl: string) {
  const payload = dataUrl.split(',')[1]

  if (!payload) {
    return 0
  }

  // base64 每 4 个字符还原 3 字节，末尾可能有填充，这里取近似值用于展示
  return Math.floor((payload.replace(/=+$/, '').length * 3) / 4)
}

/** 演示产物：已签署且有签名图时，给出可下载的签名原图 */
function buildMockArtifacts(taskId: string): SigningArtifact[] {
  const task = getMockSigningTask(taskId)

  if (!task || task.status !== 'signed' || !task.signatureDataUrl) {
    return []
  }

  return [
    {
      id: `${MOCK_SIGNATURE_PREFIX}${task.id}`,
      taskId: task.id,
      pipelineId: `mock-pipeline-${task.id}`,
      artifactType: 'SIGNATURE_IMAGE',
      label: artifactLabels.SIGNATURE_IMAGE ?? '签名原图',
      fileName: '签名原图.png',
      mimeType: 'image/png',
      sizeBytes: estimateDataUrlBytes(task.signatureDataUrl),
      sha256: '',
      metadata: {},
      createdAt: formatDateTime(task.signedAt ?? task.updatedAt),
    },
  ]
}

/** 把签名图 dataURL 还原成可下载的二进制 Blob */
function dataUrlToBlob(dataUrl: string): Blob {
  const [meta, payload] = dataUrl.split(',')
  const mimeType = /data:([^;]+)/.exec(meta ?? '')?.[1] ?? 'application/octet-stream'

  if (!payload) {
    return new Blob([], { type: mimeType })
  }

  const binary = window.atob(payload)
  const bytes = new Uint8Array(binary.length)

  for (let index = 0; index < binary.length; index += 1) {
    bytes[index] = binary.charCodeAt(index)
  }

  return new Blob([bytes], { type: mimeType })
}

export async function getSigningArtifacts(taskId: string): Promise<SigningArtifact[]> {
  if (useMockData) {
    return buildMockArtifacts(taskId)
  }

  try {
    const response = await request.get<ApiResponseOf<ArtifactCollection>>(
      `/v1/sign-artifacts/task/${encodeURIComponent(taskId)}`,
    )

    return getCollectionRecords(unwrapApiResponse(response)).map(normalizeArtifact)
  } catch (error) {
    if (axios.isAxiosError(error) && error.response?.status === 404) {
      return []
    }

    throw error
  }
}

export async function getSigningArtifact(
  taskId: string,
  artifactId: string,
): Promise<SigningArtifact | null> {
  if (useMockData) {
    return null
  }

  try {
    const response = await request.get<ApiResponseOf<SignArtifactResponseDto>>(
      `/v1/sign-artifacts/task/${encodeURIComponent(taskId)}/${encodeURIComponent(artifactId)}`,
    )

    return normalizeArtifact(unwrapApiResponse(response))
  } catch (error) {
    if (axios.isAxiosError(error) && error.response?.status === 404) {
      return null
    }

    throw error
  }
}

export function downloadSigningArtifact(artifactId: string): Promise<Blob> {
  if (useMockData) {
    // 演示环境没有文件服务，按 id 反查任务里的签名图，返回真实的 PNG
    if (artifactId.startsWith(MOCK_SIGNATURE_PREFIX)) {
      const taskId = artifactId.slice(MOCK_SIGNATURE_PREFIX.length)
      const signatureDataUrl = getMockSigningTask(taskId)?.signatureDataUrl

      if (signatureDataUrl) {
        return Promise.resolve(dataUrlToBlob(signatureDataUrl))
      }
    }

    return Promise.resolve(new Blob(['Mock 签署文件，仅用于界面演示。'], { type: 'text/plain' }))
  }

  return request.get<Blob>(`/v1/sign-artifacts/${encodeURIComponent(artifactId)}/download`, {
    responseType: 'blob',
  })
}

/** Blob → dataURL */
function blobToDataUrl(blob: Blob): Promise<string> {
  return new Promise((resolve, reject) => {
    const reader = new FileReader()
    reader.onload = () => {
      resolve(typeof reader.result === 'string' ? reader.result : '')
    }
    reader.onerror = () => {
      reject(new Error('签名图读取失败'))
    }
    reader.readAsDataURL(blob)
  })
}

/**
 * 取回签名图并转成 dataURL，供文书渲染使用。
 *
 * 签名在后端是独立的 SIGNATURE_IMAGE 产物，任务接口（SignTaskResponseDto）
 * **不返回任何签名字段**，所以前端必须自己把它取回来——否则文书里的签名位
 * 永远是「待患者签名」，导出的 PDF 也就没有患者签名。
 *
 * 这里刻意转成 dataURL 而不是直接把下载地址塞给 <img>：文书导出 PDF 走
 * html2canvas 截图，跨域的 <img src="http://..."> 会被画布安全策略拦掉
 * （`useCORS` 只在服务端返回 CORS 响应头时才生效），表现为
 * 「页面上看得到签名、导出的 PDF 里却是空的」。
 */
export async function fetchSignatureDataUrl(artifact: SigningArtifact): Promise<string> {
  try {
    return await blobToDataUrl(await downloadSigningArtifact(artifact.id))
  } catch {
    // 取签名图失败不该让整个详情页失败：正文、审计轨迹、产物列表都还能看
    return ''
  }
}

/** Restore each position from the lossless evidence sheet; legacy images remain supported. */
export async function fetchSignatureImages(
  artifact: SigningArtifact,
): Promise<Record<string, string>> {
  const source = await fetchSignatureDataUrl(artifact)
  if (!source) return {}
  const entries = artifact.metadata.signatures
  if (!Array.isArray(entries))
    return { [String(artifact.metadata.signatureFieldId || 'signature')]: source }
  if (!entries.length) return {}
  const image = new Image()
  image.src = source
  await image.decode()
  const result: Record<string, string> = {}
  for (const entry of entries) {
    if (!entry || typeof entry !== 'object') continue
    const { field, sourceX, sourceY, imageWidth, imageHeight } = entry
    if (
      typeof field?.id !== 'string' ||
      ![sourceX, sourceY, imageWidth, imageHeight].every(Number.isInteger) ||
      sourceX < 0 ||
      sourceY < 0 ||
      imageWidth <= 0 ||
      imageHeight <= 0 ||
      sourceX + imageWidth > image.naturalWidth ||
      sourceY + imageHeight > image.naturalHeight
    )
      continue
    const canvas = document.createElement('canvas')
    canvas.width = imageWidth
    canvas.height = imageHeight
    const context = canvas.getContext('2d')
    if (!context) continue
    context.drawImage(
      image,
      sourceX,
      sourceY,
      imageWidth,
      imageHeight,
      0,
      0,
      imageWidth,
      imageHeight,
    )
    result[field.id] = canvas.toDataURL('image/png')
  }
  return result
}