/**
 * exportBlocksToWord — 将 ReportBlock[] 导出为 Word (.docx)
 *
 * 与 DynamicReport.tsx 对应：将 block-based 报告序列化为 docx 格式。
 */
import {
  Document,
  Packer,
  Paragraph,
  Table,
  TableRow,
  TableCell,
  TextRun,
  HeadingLevel,
  WidthType,
  BorderStyle,
  AlignmentType,
  ImageRun,
} from 'docx';
import type { ReportBlock, ConclusionReport } from '../types';

interface ExportOptions {
  title?: string;
  subtitle?: string;
  generatedAt?: string;
  conclusion?: ConclusionReport;
}

const TABLE_BORDERS = {
  top: { style: BorderStyle.SINGLE, size: 1 },
  bottom: { style: BorderStyle.SINGLE, size: 1 },
  left: { style: BorderStyle.SINGLE, size: 1 },
  right: { style: BorderStyle.SINGLE, size: 1 },
  insideHorizontal: { style: BorderStyle.SINGLE, size: 1 },
  insideVertical: { style: BorderStyle.SINGLE, size: 1 },
};

function makeRow(cells: string[], isHeader = false): TableRow {
  return new TableRow({
    children: cells.map(text =>
      new TableCell({
        children: [
          new Paragraph({
            children: [new TextRun({ text: String(text ?? '-'), bold: isHeader })],
          }),
        ],
        width: { size: Math.floor(100 / cells.length), type: WidthType.PERCENTAGE },
      })
    ),
  });
}

function blockToDocxElements(block: ReportBlock, index: number): (Paragraph | Table)[] {
  const elements: (Paragraph | Table)[] = [];

  switch (block.type) {
    case 'key_value': {
      if (block.title) {
        elements.push(new Paragraph({ text: block.title, heading: HeadingLevel.HEADING_2 }));
      }
      const items = block.items ?? [];
      if (items.length > 0) {
        elements.push(
          new Table({
            width: { size: 100, type: WidthType.PERCENTAGE },
            borders: TABLE_BORDERS,
            rows: [
              makeRow(['指标', '值'], true),
              ...items.map(it => makeRow([it.key, it.value])),
            ],
          })
        );
        elements.push(new Paragraph({ text: '' }));
      }
      break;
    }

    case 'table': {
      const headers = block.headers ?? [];
      const rawRows = block.rows ?? [];
      if (headers.length > 0 || (Array.isArray(rawRows) && rawRows.length > 0)) {
        if (block.title) {
          elements.push(
            new Paragraph({
              text: `Table ${index + 1}. ${block.title}`,
              heading: HeadingLevel.HEADING_2,
            })
          );
        }
        const tableRows: TableRow[] = [];
        if (headers.length > 0) {
          tableRows.push(makeRow(headers.map(String), true));
        }
        const normalizedRows = (Array.isArray(rawRows) ? rawRows : []).map((row: any) => {
          if (Array.isArray(row)) return row;
          if (row && typeof row === 'object') {
            return headers.length > 0 ? headers.map((h: string) => row[h] ?? '') : Object.values(row);
          }
          return [String(row ?? '')];
        });
        for (const row of normalizedRows) {
          tableRows.push(makeRow(row.map((c: any) => (c === null || c === undefined ? '-' : String(c)))));
        }
        elements.push(
          new Table({
            width: { size: 100, type: WidthType.PERCENTAGE },
            borders: TABLE_BORDERS,
            rows: tableRows,
          })
        );
        if (block.footnote) {
          elements.push(
            new Paragraph({
              children: [new TextRun({ text: block.footnote, italics: true, color: '999999', size: 18 })],
            })
          );
        }
        elements.push(new Paragraph({ text: '' }));
      }
      break;
    }

    case 'image': {
      if (block.data) {
        try {
          const raw = block.data.replace(/^data:image\/\w+;base64,/, '');
          const imageBuffer = Uint8Array.from(atob(raw), c => c.charCodeAt(0));
          if (block.title) {
            elements.push(
              new Paragraph({
                text: `Figure ${index + 1}. ${block.title}`,
                heading: HeadingLevel.HEADING_2,
              })
            );
          }
          elements.push(
            new Paragraph({
              children: [
                new ImageRun({ data: imageBuffer, transformation: { width: 450, height: 300 }, type: 'png' }),
              ],
              alignment: AlignmentType.CENTER,
            })
          );
          elements.push(new Paragraph({ text: '' }));
        } catch {
          /* skip broken image */
        }
      }
      break;
    }

    case 'markdown': {
      if (block.title) {
        elements.push(new Paragraph({ text: block.title, heading: HeadingLevel.HEADING_2 }));
      }
      if (block.content) {
        for (const line of block.content.split('\n')) {
          if (line.trim()) {
            elements.push(new Paragraph({ text: line }));
          }
        }
        elements.push(new Paragraph({ text: '' }));
      }
      break;
    }
  }

  return elements;
}

function conclusionToDocxElements(conclusion: ConclusionReport): (Paragraph | Table)[] {
  const elements: (Paragraph | Table)[] = [];

  elements.push(new Paragraph({ text: '综合结论', heading: HeadingLevel.HEADING_1 }));
  elements.push(new Paragraph({ text: '' }));

  // Executive Summary
  elements.push(new Paragraph({ text: '摘要', heading: HeadingLevel.HEADING_2 }));
  for (const line of conclusion.executive_summary.split('\n')) {
    if (line.trim()) {
      elements.push(new Paragraph({ text: line }));
    }
  }
  elements.push(new Paragraph({ text: '' }));

  // Key Findings
  if (conclusion.key_findings.length > 0) {
    elements.push(new Paragraph({ text: '主要发现', heading: HeadingLevel.HEADING_2 }));
    for (const finding of conclusion.key_findings) {
      elements.push(
        new Paragraph({
          children: [new TextRun({ text: `• ${finding}` })],
        })
      );
    }
    elements.push(new Paragraph({ text: '' }));
  }

  // Recommendations
  if (conclusion.recommendations && conclusion.recommendations.length > 0) {
    elements.push(new Paragraph({ text: '建议', heading: HeadingLevel.HEADING_2 }));
    for (const rec of conclusion.recommendations) {
      elements.push(
        new Paragraph({
          children: [new TextRun({ text: `• ${rec}` })],
        })
      );
    }
    elements.push(new Paragraph({ text: '' }));
  }

  // Limitations
  if (conclusion.limitations.length > 0) {
    elements.push(new Paragraph({ text: '局限性', heading: HeadingLevel.HEADING_2 }));
    for (const lim of conclusion.limitations) {
      elements.push(
        new Paragraph({
          children: [new TextRun({ text: `• ${lim}` })],
        })
      );
    }
    elements.push(new Paragraph({ text: '' }));
  }

  return elements;
}

export async function exportBlocksToWord(
  blocks: ReportBlock[],
  options: ExportOptions = {}
): Promise<void> {
  const now = new Date();
  const {
    title = '统计分析报告',
    subtitle,
    generatedAt = now.toLocaleString('zh-CN'),
    conclusion,
  } = options;

  const children: (Paragraph | Table)[] = [];

  children.push(
    new Paragraph({ text: title, heading: HeadingLevel.TITLE, alignment: AlignmentType.CENTER })
  );
  if (subtitle) {
    children.push(new Paragraph({ text: subtitle, alignment: AlignmentType.CENTER }));
  }
  children.push(
    new Paragraph({
      children: [new TextRun({ text: `生成时间：${generatedAt}`, italics: true, color: '666666' })],
    }),
    new Paragraph({ text: '' })
  );

  // Phase R: Conclusion section at the top (if available)
  if (conclusion) {
    children.push(...conclusionToDocxElements(conclusion));
    children.push(new Paragraph({ text: '详细分析结果', heading: HeadingLevel.HEADING_1 }));
    children.push(new Paragraph({ text: '' }));
  }

  for (let i = 0; i < blocks.length; i++) {
    children.push(...blockToDocxElements(blocks[i], i));
  }

  children.push(
    new Paragraph({ text: '' }),
    new Paragraph({
      children: [
        new TextRun({
          text: `本报告由智能统计分析系统自动生成${conclusion?.source === 'llm' ? '（结论由 AI 生成）' : ''}`,
          italics: true,
          color: '666666',
        }),
      ],
    })
  );

  const doc = new Document({ sections: [{ children }] });
  const blob = await Packer.toBlob(doc);

  const dateStr = `${now.getFullYear()}${String(now.getMonth() + 1).padStart(2, '0')}${String(now.getDate()).padStart(2, '0')}_${String(now.getHours()).padStart(2, '0')}${String(now.getMinutes()).padStart(2, '0')}`;
  const safeTitle = title.replace(/[^a-zA-Z0-9\u4e00-\u9fa5_-]/g, '_');

  const url = URL.createObjectURL(blob);
  const a = document.createElement('a');
  a.href = url;
  a.download = `${safeTitle}_${dateStr}.docx`;
  a.click();
  URL.revokeObjectURL(url);
}