"use client"

import React, {
  useState,
  useEffect,
  useRef,
  SetStateAction,
  Dispatch,
} from "react"
import { WebViewerInstance } from "@pdftron/webviewer"
import { Loader2 } from "lucide-react"
import { toast } from "sonner"

import { type GtcClauseTreeView } from "@/db/schema/gtc"

interface ClausePreviewViewerProps {
  clauses: GtcClauseTreeView[]
  document: any
  instance: WebViewerInstance | null
  setInstance: Dispatch<SetStateAction<WebViewerInstance | null>>
}

export function ClausePreviewViewer({
  clauses,
  document,
  instance,
  setInstance,
}: ClausePreviewViewerProps) {
  const [fileLoading, setFileLoading] = useState<boolean>(true)
  const viewer = useRef<HTMLDivElement>(null)
  const initialized = useRef(false)
  const isCancelled = useRef(false)

  // WebViewer 초기화
  useEffect(() => {
    if (!initialized.current && viewer.current) {
      initialized.current = true
      isCancelled.current = false

      requestAnimationFrame(() => {
        if (viewer.current) {
          import("@pdftron/webviewer").then(({ default: WebViewer }) => {
            if (isCancelled.current) {
              console.log("📛 WebViewer 초기화 취소됨")
              return
            }

            const viewerElement = viewer.current
            if (!viewerElement) return

            WebViewer(
              {
                path: "/pdftronWeb",
                licenseKey: process.env.NEXT_PUBLIC_PDFTRON_WEBVIEW_KEY,
                fullAPI: true,
                enableOfficeEditing: true,
                l: "ko",
                // 미리보기 모드로 설정
                enableReadOnlyMode: false,
              },
              viewerElement
            ).then(async (instance: WebViewerInstance) => {
              setInstance(instance)
              
              try {
                const { disableElements, enableElements, setToolbarGroup } = instance.UI

                // 미리보기에 필요한 도구만 활성화
                enableElements([
                  "toolbarGroup-View",
                  "zoomInButton",
                  "zoomOutButton",
                  "fitButton",
                  "rotateCounterClockwiseButton",
                  "rotateClockwiseButton",
                ])

                // 편집 도구는 비활성화
                disableElements([
                  "toolbarGroup-Edit",
                  "toolbarGroup-Insert",
                  "toolbarGroup-Annotate",
                  "toolbarGroup-Shapes",
                  "toolbarGroup-Forms",
                ])
                
                setToolbarGroup("toolbarGroup-View")
                
                // 조항 데이터로 문서 생성
                await generateDocumentFromClauses(instance, clauses, document)
                
              } catch (uiError) {
                console.warn("⚠️ UI 설정 중 오류:", uiError)
              } finally {
                setFileLoading(false)
              }
            }).catch((error) => {
              console.error("❌ WebViewer 초기화 실패:", error)
              setFileLoading(false)
              toast.error("뷰어 초기화에 실패했습니다.")
            })
          })
        }
      })
    }

    return () => {
      if (instance) {
        instance.UI.dispose()
      }
      isCancelled.current = true
    }
  }, [])

  // 조항 데이터로 워드 문서 생성
  const generateDocumentFromClauses = async (
    instance: WebViewerInstance, 
    clauses: GtcClauseTreeView[], 
    document: any
  ) => {
    try {
      console.log("📄 조항 기반 DOCX 문서 생성 시작:", clauses.length)
      
      // 활성화된 조항만 필터링하고 정렬
      const activeClauses = clauses
        .filter(clause => clause.isActive !== false)
        .sort((a, b) => {
          // sortOrder 또는 itemNumber로 정렬
          if (a.sortOrder && b.sortOrder) {
            return parseFloat(a.sortOrder) - parseFloat(b.sortOrder)
          }
          return a.itemNumber.localeCompare(b.itemNumber, undefined, { numeric: true })
        })

      // ✅ DOCX 문서 생성
      const docxBlob = await generateDocxDocument(activeClauses, document)
      
      // ✅ DOCX 파일로 변환
      const docxFile = new File([docxBlob], `${document?.title || 'GTC계약서'}_미리보기.docx`, { 
        type: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' 
      })
      
      // ✅ PDFTron에서 DOCX 문서로 로드
      await instance.UI.loadDocument(docxFile, {
        filename: `${document?.title || 'GTC계약서'}_미리보기.docx`,
        enableOfficeEditing: true, // DOCX 편집 모드 활성화
      })
      
      console.log("✅ DOCX 기반 문서 생성 완료")
      toast.success("Word 문서 미리보기가 생성되었습니다.")
      
    } catch (err) {
      console.error("❌ DOCX 문서 생성 중 오류:", err)
      toast.error(`문서 생성 실패: ${err instanceof Error ? err.message : '알 수 없는 오류'}`)
    }
  }

  return (
    <div className="relative w-full h-full overflow-hidden">
      <div 
        ref={viewer} 
        className="w-full h-full"
        style={{
          position: 'relative',
          overflow: 'hidden',
          contain: 'layout style paint',
        }}
      >
        {fileLoading && (
          <div className="absolute inset-0 flex flex-col items-center justify-center bg-white bg-opacity-90 z-10">
            <Loader2 className="h-8 w-8 text-blue-500 animate-spin mb-4" />
            <p className="text-sm text-muted-foreground">문서 생성 중...</p>
            <p className="text-xs text-muted-foreground mt-1">
              {clauses.filter(c => c.isActive !== false).length}개 조항 처리 중
            </p>
          </div>
        )}
      </div>
    </div>
  )
}



// ===== data URL 판별 및 디코딩 유틸 =====
function isDataUrl(url: string) {
    return /^data:/.test(url);
  }
  
  function dataUrlToUint8Array(dataUrl: string): { bytes: Uint8Array; mime: string } {
    // 형식: data:<mime>;base64,<payload>
    const match = dataUrl.match(/^data:([^;]+);base64,(.*)$/);
    if (!match) {
      // base64가 아닌 data URL도 가능하지만, 여기서는 base64만 지원
      throw new Error("지원하지 않는 data URL 형식입니다.");
    }
    const mime = match[1];
    const base64 = match[2];
    const binary = atob(base64);
    const len = binary.length;
    const bytes = new Uint8Array(len);
    for (let i = 0; i < len; i++) bytes[i] = binary.charCodeAt(i);
    return { bytes, mime };
  }
  
  // ===== helper: 이미지 불러오기 + 크기 계산 (data:, http:, / 경로 모두 지원) =====
  async function fetchImageData(url: string, maxWidthPx = 500) {
    let blob: Blob;
    let bytes: Uint8Array;
  
    if (isDataUrl(url)) {
      // data URL → Uint8Array, Blob
      const { bytes: arr, mime } = dataUrlToUint8Array(url);
      bytes = arr;
      blob = new Blob([bytes], { type: mime });
    } else {
      // http(s) 또는 상대 경로
      const res = await fetch(url, { cache: "no-store" });
      if (!res.ok) throw new Error(`이미지 다운로드 실패 (${res.status})`);
      blob = await res.blob();
      const arrayBuffer = await blob.arrayBuffer();
      bytes = new Uint8Array(arrayBuffer);
    }
  
    // 원본 크기 파악 (공통)
    const dims = await new Promise<{ width: number; height: number }>((resolve) => {
      const img = new Image();
      const objectUrl = URL.createObjectURL(blob);
      img.onload = () => {
        const width = img.naturalWidth || 800;
        const height = img.naturalHeight || 600;
        URL.revokeObjectURL(objectUrl);
        resolve({ width, height });
      };
      img.onerror = () => {
        URL.revokeObjectURL(objectUrl);
        resolve({ width: 800, height: 600 }); // 실패 시 기본값
      };
      img.src = objectUrl;
    });
  
    // 비율 유지 축소
    const scale = Math.min(1, maxWidthPx / (dims.width || maxWidthPx));
    const width = Math.round((dims.width || maxWidthPx) * scale);
    const height = Math.round((dims.height || Math.round(maxWidthPx * 0.6)) * scale);
  
    return { data: bytes, width, height };
  }

// DOCX 문서 생성 (docx 라이브러리 사용)
async function generateDocxDocument(
    clauses: GtcClauseTreeView[], 
    document: any
  ): Promise<Blob> {
    const { Document, Packer, Paragraph, TextRun, AlignmentType, ImageRun } = await import("docx");
  
    
function textToParagraphs(text: string, indentLeft: number) {
    const lines = text.split("\n");
    return [
      new Paragraph({
        children: lines
          .map((line, i) => [
            new TextRun({ text: line }),
            ...(i < lines.length - 1 ? [new TextRun({ break: 1 })] : []),
          ])
          .flat(),
        indent: { left: indentLeft },
      }),
    ];
  }
  
  const IMG_TOKEN = /!\[([^\]]+)\]/g; // 예: ![image1753698566087]


async function pushContentWithInlineImages(
    content: string,
    indentLeft: number,
    children: any[],
    imageMap: Map<string, any>
  ) {
    let lastIndex = 0;
    for (const match of content.matchAll(IMG_TOKEN)) {
      const start = match.index ?? 0;
      const end = start + match[0].length;
      const imageId = match[1];
  
      // 앞부분 텍스트
      if (start > lastIndex) {
        const txt = content.slice(lastIndex, start);
        children.push(...textToParagraphs(txt, indentLeft));
      }
  
      // 이미지 삽입
      const imgMeta = imageMap.get(imageId);
      if (imgMeta?.url) {
        const { data, width, height } = await fetchImageData(imgMeta.url, 520);
        children.push(
          new Paragraph({
            children: [
              new ImageRun({
                data,
                transformation: { width, height },
              }),
            ],
            indent: { left: indentLeft },
          })
        );
        // 사용된 이미지 표시(뒤에서 중복 추가 방지)
        imageMap.delete(imageId);
      }
      // 매칭 실패 시: 아무것도 넣지 않음(토큰 제거)
  
      lastIndex = end;
    }
  
    // 남은 꼬리 텍스트
    if (lastIndex < content.length) {
      const tail = content.slice(lastIndex);
      children.push(...textToParagraphs(tail, indentLeft));
    }
  }
  
  
    const documentTitle = document?.title || "GTC 계약서";
    const currentDate = new Date().toLocaleDateString("ko-KR");
  
    // depth 추정/정렬
    const structuredClauses = organizeClausesByHierarchy(clauses);
  
    const children: any[] = [
      new Paragraph({
        alignment: AlignmentType.CENTER,
        children: [new TextRun({ text: documentTitle, bold: true, size: 32 })],
      }),
      new Paragraph({
        alignment: AlignmentType.CENTER,
        children: [new TextRun({ text: `생성일: ${currentDate}`, size: 20, color: "666666" })],
      }),
      new Paragraph({ text: "" }),
      new Paragraph({ text: "" }),
    ];
  
    for (const clause of structuredClauses) {
      const depth = Math.min(clause.estimatedDepth || 0, 3);
      const indentLeft = depth * 400;       // 번호/제목
      const indentContent = indentLeft + 200; // 본문/이미지
  
      // 번호 + 제목
      children.push(
        new Paragraph({
          children: [
            new TextRun({ text: `${clause.itemNumber}${clause.subtitle ? "." : ""}`, bold: true, color: "2563eb" }),
            ...(clause.subtitle
              ? [new TextRun({ text: " " }), new TextRun({ text: clause.subtitle, bold: true })]
              : []),
          ],
          indent: { left: indentLeft },
        })
      );
  
      const imageMap = new Map(
        Array.isArray((clause as any).images)
          ? (clause as any).images.map((im: any) => [String(im.id), im])
          : []
      );
  
      // 내용
      const hasContent = clause.content && clause.content.trim();
      if (hasContent) {
        await pushContentWithInlineImages(clause.content!, indentContent, children, imageMap);
      }
  
    //   else {
    //     children.push(
    //       new Paragraph({
    //         // children: [new TextRun({ text: "(상세 내용 없음)", italics: true, color: "6b7280", size: 20 })],
    //         indent: { left: indentContent },
    //       })
    //     );
    //   }
  
        // 본문에 등장하지 않은 잔여 이미지(선택: 뒤에 추가)

      for (const [, imgMeta] of imageMap) {
        try {
          const { data, width, height } = await fetchImageData(imgMeta.url, 520);
          children.push(
            new Paragraph({
              children: [new ImageRun({ data, transformation: { width, height } })],
              indent: { left: indentContent },
            })
          );
        } catch (e) {
          children.push(
            new Paragraph({
              children: [new TextRun({ text: `이미지 로드 실패: ${imgMeta.fileName || imgMeta.url}`, color: "b91c1c", size: 20 })],
              indent: { left: indentContent },
            })
          );
          console.warn("이미지 로드 실패(잔여):", imgMeta, e);
        }
      }
  
      // 조항 간 간격
      children.push(new Paragraph({ text: "" }));
    }
  
    const doc = new Document({
      sections: [{ properties: {}, children }],
    });
  
    return await Packer.toBlob(doc);
  }

// 조항들을 계층구조로 정리
function organizeClausesByHierarchy(clauses: GtcClauseTreeView[]) {
  // depth가 없는 경우 itemNumber로 depth 추정
  return clauses.map(clause => ({
    ...clause,
    estimatedDepth: clause.depth ?? estimateDepthFromItemNumber(clause.itemNumber)
  })).sort((a, b) => {
    // itemNumber 기준 자연 정렬
    return a.itemNumber.localeCompare(b.itemNumber, undefined, { 
      numeric: true, 
      sensitivity: 'base' 
    })
  })
}

// itemNumber로부터 depth 추정
function estimateDepthFromItemNumber(itemNumber: string): number {
  const parts = itemNumber.split('.')
  return Math.max(0, parts.length - 1)
}