import { BrowserWindow, dialog } from 'electron'
import { writeFileSync } from 'fs'
import type { ExportMatrixParams } from '../../shared/export-matrix'
import type { ExportChapterBlock } from '../lib/export-content'
import {
  buildExportBlocks,
  buildMdExport,
  buildTxtExport,
  resolveExportChapters
} from '../lib/export-content'
import type { BookRegistryService } from './book-registry'
import type { GlobalSettingsService } from './global-settings'

const FORMAT_EXT: Record<ExportMatrixParams['format'], string> = {
  txt: 'txt',
  md: 'md',
  docx: 'docx',
  pdf: 'pdf'
}

export class ExportMatrixService {
  constructor(
    private registry: BookRegistryService,
    private settings: GlobalSettingsService
  ) {}

  collectBlocks(params: ExportMatrixParams): ExportChapterBlock[] {
    const db = this.registry.getDb(params.bookId)
    const chapters = resolveExportChapters(db, params.scope, params.scopeId)
    if (chapters.length === 0) throw new Error('No chapters to export')
    return buildExportBlocks(db, chapters, params.options)
  }

  async exportToPath(params: ExportMatrixParams, destPath: string): Promise<void> {
    const blocks = this.collectBlocks(params)
    const book = this.registry.list().find((b) => b.id === params.bookId)
    const bookName = book?.name ?? 'export'
    const { penName } = this.settings.get()

    switch (params.format) {
      case 'txt':
        writeFileSync(destPath, buildTxtExport(blocks), 'utf8')
        break
      case 'md':
        writeFileSync(destPath, buildMdExport(blocks), 'utf8')
        break
      case 'docx':
        writeFileSync(destPath, await this.buildDocxBuffer(blocks, bookName))
        break
      case 'pdf':
        await this.exportPdf(blocks, bookName, penName, destPath)
        break
      default:
        throw new Error(`Unsupported format: ${params.format}`)
    }
  }

  async pickAndExport(params: ExportMatrixParams): Promise<string | null> {
    const ext = FORMAT_EXT[params.format]
    let destPath: string | null = null
    if (process.env.BILIN_E2E === '1' && process.env.BILIN_E2E_PDF_SAVE) {
      destPath = process.env.BILIN_E2E_PDF_SAVE
    } else {
      const book = this.registry.list().find((b) => b.id === params.bookId)
      const defaultPath = `${book?.name ?? 'export'}.${ext}`
      const { canceled, filePath } = await dialog.showSaveDialog({
        defaultPath,
        filters: [{ name: ext.toUpperCase(), extensions: [ext] }]
      })
      if (canceled || !filePath) return null
      destPath = filePath
    }
    await this.exportToPath(params, destPath)
    return destPath
  }

  private async buildDocxBuffer(blocks: ExportChapterBlock[], bookName: string): Promise<Buffer> {
    const docx = await import('docx')
    const {
      Document,
      Packer,
      Paragraph,
      TextRun,
      HeadingLevel,
      TableOfContents,
      AlignmentType,
      PageBreak
    } = docx

    const children: InstanceType<typeof Paragraph>[] = [
      new Paragraph({
        text: bookName,
        heading: HeadingLevel.TITLE,
        alignment: AlignmentType.CENTER
      }),
      new TableOfContents('目录', { hyperlink: true, headingStyleRange: '1-1' }),
      new Paragraph({ children: [new PageBreak()] })
    ]

    for (const block of blocks) {
      children.push(
        new Paragraph({
          text: block.title,
          heading: HeadingLevel.HEADING_1
        })
      )
      if (block.hasAiContent) {
        children.push(
          new Paragraph({
            children: [new TextRun({ text: '[AI生成内容]', italics: true, color: '888888' })]
          })
        )
      }
      for (const p of block.paragraphs) {
        children.push(new Paragraph({ children: [new TextRun(p)] }))
      }
      if (block.annotations.length > 0) {
        children.push(
          new Paragraph({
            children: [new TextRun({ text: '批注', bold: true })]
          })
        )
        for (const note of block.annotations) {
          children.push(
            new Paragraph({
              children: [new TextRun({ text: `• ${note}`, size: 20 })]
            })
          )
        }
      }
    }

    const doc = new Document({
      features: { updateFields: true },
      sections: [{ children }]
    })
    return Packer.toBuffer(doc)
  }

  private buildPdfHtml(blocks: ExportChapterBlock[], bookName: string, penName: string): string {
    const exportedAt = new Date().toLocaleDateString('zh-CN')
    const chaptersHtml = blocks
      .map((block, idx) => {
        const ai = block.hasAiContent ? '<p class="ai-badge">[AI生成内容]</p>' : ''
        const body = block.paragraphs.map((p) => `<p>${escapeHtml(p)}</p>`).join('')
        const notes =
          block.annotations.length > 0
            ? `<div class="annotations"><strong>批注</strong><ul>${block.annotations.map((a) => `<li>${escapeHtml(a)}</li>`).join('')}</ul></div>`
            : ''
        return `<section class="chapter"><h2>${idx + 1}. ${escapeHtml(block.title)}</h2>${ai}${body}${notes}</section>`
      })
      .join('')

    return `<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8"/>
<style>
  @page { margin: 2cm 2cm 2.5cm 2cm; }
  body { font-family: 'Noto Serif SC', Georgia, serif; font-size: 12pt; line-height: 1.8; color: #222; }
  .print-header { font-size: 9pt; color: #666; border-bottom: 1px solid #ccc; padding-bottom: 6px; margin-bottom: 24px; display: flex; justify-content: space-between; }
  .chapter { page-break-before: always; }
  .chapter:first-of-type { page-break-before: auto; }
  h2 { font-size: 16pt; margin: 0 0 12px; }
  .ai-badge { font-size: 9pt; color: #888; }
  .annotations { font-size: 9pt; color: #555; margin-top: 16px; border-top: 1px dashed #ccc; padding-top: 8px; }
  .print-footer { font-size: 9pt; color: #666; margin-top: 32px; border-top: 1px solid #ccc; padding-top: 6px; display: flex; justify-content: space-between; }
</style>
</head>
<body>
  <div class="print-header">
    <span>${escapeHtml(bookName)}</span>
    <span>笔临导出</span>
    <span></span>
  </div>
  ${chaptersHtml}
  <div class="print-footer">
    <span>${escapeHtml(penName)}</span>
    <span>${exportedAt}</span>
  </div>
</body>
</html>`
  }

  private async exportPdf(
    blocks: ExportChapterBlock[],
    bookName: string,
    penName: string,
    destPath: string
  ): Promise<void> {
    const html = this.buildPdfHtml(blocks, bookName, penName)
    const win = new BrowserWindow({
      show: false,
      webPreferences: { offscreen: true }
    })
    try {
      await win.loadURL(`data:text/html;charset=utf-8,${encodeURIComponent(html)}`)
      await new Promise<void>((resolve) => setTimeout(resolve, 300))
      const pdf = await win.webContents.printToPDF({
        printBackground: true,
        pageSize: 'A4',
        margins: { top: 0.5, bottom: 0.5, left: 0.5, right: 0.5 }
      })
      writeFileSync(destPath, pdf)
    } finally {
      win.destroy()
    }
  }
}

function escapeHtml(text: string): string {
  return text
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
}