import React, { useState, useRef } from 'react';
import cx from 'classnames';
import Spin from '../../ui/Spin';
import { DocumentIcon } from '../../icons/Document';
import Modal from '../../ui/Modal';
import { useTranslation } from 'react-i18next';
import memoriApiClient from '@memori.ai/memori-api-client';
import { officeNativeExtensions } from '../../../helpers/constants';
import { isOfficeNativeFilename } from '../../../helpers/utils';
// Types
type PreviewFile = {
  name: string;
  id: string;
  content: string;
  type: 'document';
  previewUrl?: string;
  uploaded?: boolean;
  error?: boolean;
};

// Constants
const PDF_JS_VERSION = '3.11.174';
const WORKER_URL = `https://cdnjs.cloudflare.com/ajax/libs/pdf.js/${PDF_JS_VERSION}/pdf.worker.min.js`;
const PDF_JS_URL = `https://cdnjs.cloudflare.com/ajax/libs/pdf.js/${PDF_JS_VERSION}/pdf.min.js`;
const XLSX_URL =
  'https://cdn.sheetjs.com/xlsx-0.20.0/package/dist/xlsx.full.min.js';

// Add type definitions for external libraries
declare global {
  interface Window {
    pdfjsLib: any;
    XLSX: any;
  }
}

// Props interface
interface UploadDocumentsProps {
  setDocumentPreviewFiles: (
    files: {
      name: string;
      id: string;
      content: string;
      mimeType: string;
      textAssetUrl?: string;
    }[]
  ) => void;
  authToken?: string;
  client?: ReturnType<typeof memoriApiClient>;
  sessionID?: string;
  memoriID?: string;
  maxDocuments?: number;
  documentPreviewFiles: any;
  onLoadingChange?: (loading: boolean, fileCount?: number) => void;
  onDocumentError?: (error: {
    message: string;
    severity: 'error' | 'warning' | 'info';
  }) => void;
  onValidateFile?: (file: File) => boolean;
  onValidatePayloadSize?: (
    newDocuments: {
      name: string;
      id: string;
      content: string;
      mimeType: string;
    }[]
  ) => boolean | { valid: boolean; message?: string };
}

const UploadDocuments: React.FC<UploadDocumentsProps> = ({
  setDocumentPreviewFiles,
  authToken = '',
  client,
  sessionID = '',
  memoriID = '',
  maxDocuments,
  documentPreviewFiles,
  onLoadingChange,
  onDocumentError,
  onValidateFile,
  onValidatePayloadSize,
}) => {
  const { t } = useTranslation();
  const { backend } = client || {
    backend: { uploadAsset: null, uploadAssetUnlogged: null },
  };

  // State
  const [isLoading, setIsLoading] = useState(false);
  const [selectedFile, setSelectedFile] = useState<PreviewFile | null>(null);

  // Refs
  const documentInputRef = useRef<HTMLInputElement>(null);

  const setLoadingState = (loading: boolean, fileCount?: number) => {
    setIsLoading(loading);
    onLoadingChange?.(loading, fileCount);
  };

  // Document upload
  const validateDocumentFile = (file: File): boolean => {
    if (onValidateFile) {
      return onValidateFile(file);
    }
    return true;
  };

  // Validate total payload size (returns result object for conditional error display)
  const validatePayloadSize = (
    newDocuments: {
      name: string;
      id: string;
      content: string;
      mimeType: string;
    }[]
  ): { valid: boolean; message?: string } => {
    if (onValidatePayloadSize) {
      const result = onValidatePayloadSize(newDocuments);
      if (typeof result === 'boolean') {
        return result ? { valid: true } : { valid: false, message: '' };
      }
      return result;
    }
    return { valid: true };
  };

  const extractTextFromPDF = async (file: File): Promise<string> => {
    try {
      // Load PDF.js if not already loaded
      if (!window.pdfjsLib) {
        await new Promise((resolve, reject) => {
          const script = document.createElement('script');
          script.src = PDF_JS_URL;
          script.onload = () => {
            window.pdfjsLib.GlobalWorkerOptions.workerSrc = WORKER_URL;
            resolve(true);
          };
          script.onerror = reject;
          document.head.appendChild(script);
        });
      }

      // Extract text from PDF
      const arrayBuffer = await file.arrayBuffer();
      const pdf = await window.pdfjsLib.getDocument({ data: arrayBuffer })
        .promise;
      let text = '';

      // Iterate through each page and extract text
      for (let i = 1; i <= pdf.numPages; i++) {
        const page = await pdf.getPage(i);
        const content = await page.getTextContent();
        const pageText = content.items
          .filter((item: any) => item.str && typeof item.str === 'string')
          .map((item: any) => item.str)
          .join(' ');
        text += pageText + '\n';
      }

      return text;
    } catch (error) {
      console.error('PDF extraction failed:', error);
      throw new Error(
        `PDF extraction failed: ${
          error instanceof Error ? error.message : 'Unknown error'
        }`
      );
    }
  };

  const extractTextFromXLSX = async (file: File): Promise<string> => {
    try {
      if (!window.XLSX) {
        await new Promise((resolve, reject) => {
          const script = document.createElement('script');
          script.src = XLSX_URL;
          script.onload = resolve;
          script.onerror = reject;
          document.head.appendChild(script);
        });
      }

      const arrayBuffer = await file.arrayBuffer();
      const workbook = window.XLSX.read(arrayBuffer, {
        type: 'array',
        cellFormula: true,
        cellNF: true,
        cellText: true,
        cellDates: true,
      });

      let text = '';
      for (const sheetName of workbook.SheetNames) {
        const worksheet = workbook.Sheets[sheetName];
        const data = window.XLSX.utils.sheet_to_json(worksheet, {
          header: 1,
          raw: false,
        });

        const colWidths = data.reduce((widths: number[], row: any[]) => {
          row.forEach((cell, i) => {
            const cellWidth = (cell || '').toString().length;
            widths[i] = Math.max(widths[i] || 0, cellWidth);
          });
          return widths;
        }, []);

        const formattedText = data.map((row: any[]) => {
          return row
            .map((cell, i) => {
              const cellStr = (cell || '').toString();
              return cellStr.padEnd(colWidths[i] + 2);
            })
            .join('|')
            .trim();
        });

        if (formattedText.length > 0) {
          const separator = colWidths
            .map((w: number) => '-'.repeat(w + 2))
            .join('+');
          formattedText.splice(1, 0, separator);
        }

        text += `Sheet: ${sheetName}\n${formattedText.join('\n')}\n\n`;
      }

      return text;
    } catch (error) {
      console.error('XLSX extraction failed:', error);
      throw new Error(
        `XLSX extraction failed: ${
          error instanceof Error ? error.message : 'Unknown error'
        }`
      );
    }
  };

  const processDocumentFile = async (
    file: File
  ): Promise<{ text: string | null; uploadAsOriginal?: boolean }> => {
    if (isOfficeNativeFilename(file.name)) {
      return { text: null, uploadAsOriginal: true };
    }

    const ext = file.name.split('.').pop()?.toLowerCase() || '';
    try {
      let text: string | null = null;

      if (ext === 'pdf') {
        text = await extractTextFromPDF(file);
      } else if (['txt', 'md', 'json', 'csv', 'html'].includes(ext)) {
        text = await file.text();
      } else if (ext === 'xlsx') {
        text = await extractTextFromXLSX(file);
      }

      return { text };
    } catch (error) {
      console.error('Document processing failed:', error);
      throw new Error(
        `Failed to process "${file.name}": ${
          error instanceof Error ? error.message : 'Unknown error'
        }`
      );
    }
  };

  const fileToDataUrl = (file: File): Promise<string> =>
    new Promise((resolve, reject) => {
      const reader = new FileReader();
      reader.onload = e => resolve((e.target?.result as string) || '');
      reader.onerror = () => reject(new Error('File reading failed'));
      reader.readAsDataURL(file);
    });

  const uploadAssetFile = async (file: File): Promise<string> => {
    if (!client) {
      throw new Error('API client not configured properly for media upload');
    }

    const fileDataUrl = await fileToDataUrl(file);
    let response: any;
    if (authToken && backend?.uploadAsset) {
      response = await backend.uploadAsset(file.name, fileDataUrl, authToken);
    } else if (memoriID && sessionID && backend?.uploadAssetUnlogged) {
      response = await backend.uploadAssetUnlogged(
        file.name,
        fileDataUrl,
        memoriID,
        sessionID
      );
    } else {
      throw new Error('Missing required parameters for upload');
    }

    if (!response) {
      throw new Error('Upload failed');
    }
    if (response.resultCode !== 0) {
      throw new Error(response.resultMessage || 'Upload failed');
    }

    const assetURL = response.asset?.assetURL;
    if (!assetURL) {
      throw new Error('Upload failed: missing asset URL');
    }

    return assetURL;
  };

  const handleDocumentUpload = async (
    e: React.ChangeEvent<HTMLInputElement>
  ) => {
    const files = Array.from(e.target.files || []);
    if (files.length === 0) return;

    // Check current total media count (images + documents)
    const currentMediaCount = documentPreviewFiles.length;
    const remainingSlots = maxDocuments
      ? Math.max(0, maxDocuments - currentMediaCount)
      : files.length;
    const filesToProcess = files.slice(0, remainingSlots);

    if (files.length > filesToProcess.length) {
      const skipped = files.length - filesToProcess.length;
      onDocumentError?.({
        message:
          t('upload.documentsNotAddedMaxAllowed', {
            count: skipped,
            max: maxDocuments ?? 10,
            defaultValue: `${skipped} document(s) not added (maximum ${
              maxDocuments ?? 10
            } files allowed).`,
          }) ??
          `${skipped} document(s) not added (maximum ${
            maxDocuments ?? 10
          } files allowed).`,
        severity: 'warning',
      });
    }

    if (filesToProcess.length === 0) {
      if (documentInputRef.current) {
        documentInputRef.current.value = '';
      }
      return;
    }

    setLoadingState(true, filesToProcess.length);

    try {
      // Process each file
      const processedFiles: {
        name: string;
        id: string;
        content: string;
        mimeType: string;
        textAssetUrl?: string;
      }[] = [];

      let activeCount = filesToProcess.length;

      for (const file of filesToProcess) {
        if (!validateDocumentFile(file)) {
          activeCount--;
          onLoadingChange?.(true, activeCount);
          continue;
        }

        const fileId = Math.random().toString(36).substr(2, 9);

        try {
          const { text, uploadAsOriginal } = await processDocumentFile(file);

          if (uploadAsOriginal) {
            // Office native format: upload the original file as asset, no text extraction
            let assetUrl: string | undefined;
            try {
              assetUrl = await uploadAssetFile(file);
            } catch (uploadError) {
              console.error('Office asset upload failed:', uploadError);
              onDocumentError?.({
                message: t('upload.officeAssetUploadFailed', {
                  fileName: file.name,
                  defaultValue: `"${file.name}" could not be uploaded and was not added.`,
                }),
                severity: 'error',
              });
            }

            if (!assetUrl) {
              activeCount--;
              onLoadingChange?.(true, activeCount);
              continue;
            }

            processedFiles.push({
              name: file.name,
              id: fileId,
              content: '',
              mimeType: file.type,
              textAssetUrl: assetUrl,
            });
          } else if (text) {
            const baseName = file.name.replace(/\.[^/.]+$/, '') || file.name;
            const textFile = new File([text], `${baseName}.txt`, {
              type: 'text/plain',
            });

            let textAssetUrl: string | undefined;
            try {
              textAssetUrl = await uploadAssetFile(textFile);
            } catch (uploadError) {
              console.error('Text asset upload failed:', uploadError);
              onDocumentError?.({
                message: t('upload.partialAssetUploadWarning', {
                  fileName: file.name,
                  defaultValue:
                    'Some file links could not be uploaded, but the document was added anyway.',
                }),
                severity: 'warning',
              });
            }

            processedFiles.push({
              name: file.name,
              id: fileId,
              content: text,
              mimeType: file.type,
              textAssetUrl,
            });
          } else {
            activeCount--;
            onLoadingChange?.(true, activeCount);
          }
        } catch (error) {
          activeCount--;
          onLoadingChange?.(true, activeCount);
          console.error('File processing error:', error);
          onDocumentError?.({
            message: `${
              error instanceof Error ? error.message : 'Unknown error'
            }`,
            severity: 'warning',
          });
        }
      }

      if (processedFiles.length > 0) {
        setDocumentPreviewFiles(
          processedFiles.map(file => ({
            ...file,
            type: 'document',
          }))
        );
      }
    } finally {
      setLoadingState(false);
      if (documentInputRef.current) {
        documentInputRef.current.value = '';
      }
    }
  };

  return (
    <div className="memori--document-upload-wrapper">
      {/* Hidden file input */}
      <input
        ref={documentInputRef}
        type="file"
        accept={`.pdf,.txt,.md,.json,.xlsx,.csv,.html,${officeNativeExtensions.join(',')}`}
        multiple
        className="memori--upload-file-input"
        onChange={handleDocumentUpload}
      />

      {/* Upload document button */}
      <button
        className={cx(
          'memori-button',
          'memori-button--circle',
          'memori-button--icon-only',
          'memori-share-button--button',
          'memori--conversation-button',
          'memori--document-upload-button',
          { 'memori--error': false } // Removed errors.length > 0
        )}
        onClick={() => documentInputRef.current?.click()}
        disabled={
          isLoading ||
          (maxDocuments && documentPreviewFiles.length >= maxDocuments) ||
          false
        }
        title="Upload documents"
      >
        {isLoading ? (
          <Spin spinning className="memori--upload-icon" />
        ) : (
          <React.Fragment>
            <DocumentIcon className="memori--upload-icon" />
          </React.Fragment>
        )}
      </button>

      {/* Modal */}
      <Modal
        width="80%"
        widthMd="80%"
        open={!!selectedFile}
        className="memori--modal-preview-file"
        onClose={() => setSelectedFile(null)}
        closable
        title={selectedFile?.name}
      >
        <div
          className="memori--preview-content"
          style={{
            maxHeight: '70vh',
            overflowY: 'auto',
            textAlign: 'center',
            whiteSpace: 'pre-wrap',
          }}
        >
          {selectedFile?.content}
        </div>
      </Modal>
    </div>
  );
};

export default UploadDocuments;