// DOCX export — kept in its own module so the (large) `docx` library is only
// downloaded when the user actually exports, instead of on every page load.
import {
  BorderStyle,
  Document,
  HeadingLevel,
  Packer,
  Paragraph,
  Table,
  TableCell,
  TableRow,
  TextRun,
  WidthType,
} from 'docx';
import { formatChunkReference, getChunkVerseEntries, htmlToPlainText } from './bibleUtils.jsx';

export function createParagraphsFromText(text) {
  return text
    .split(/\n+/)
    .map((line) => line.trim())
    .filter(Boolean)
    .map((line) => new Paragraph({ children: [new TextRun({ text: line })] }));
}

const DOCX_ACCENT = 'C9A84C'; // antique gold
const DOCX_HEADING_FONT = 'Cormorant Garamond';
const DOCX_BODY_FONT = 'Lora';

export function sectionLabel(text) {
  return new Paragraph({
    spacing: { before: 240, after: 80 },
    children: [
      new TextRun({
        text: text.toUpperCase(),
        bold: true,
        color: DOCX_ACCENT,
        font: DOCX_BODY_FONT,
        size: 20,
        characterSpacing: 20,
      }),
    ],
  });
}

export async function buildStudyDocxBlob(project, chapterSummary) {
  const children = [
    new Paragraph({ text: project.title, heading: HeadingLevel.TITLE }),
    new Paragraph({
      children: [
        new TextRun({
          text: `${project.translation} — ${chapterSummary}`,
          italics: true,
          color: '7A7060',
        }),
      ],
      spacing: { after: 300 },
    }),
  ];

  const noBorder = { style: BorderStyle.NONE, size: 0, color: 'FFFFFF' };

  project.chapters.forEach((ch, chapterIndex) => {
    children.push(new Paragraph({
      text: `${ch.book} ${ch.chapter}`,
      heading: HeadingLevel.HEADING_1,
      border: { bottom: { style: BorderStyle.SINGLE, size: 6, color: DOCX_ACCENT, space: 4 } },
      spacing: { before: 360, after: 160 },
    }));
    ch.chunks.forEach((chunk) => {
      const scriptureHeading = formatChunkReference(project, chapterIndex, chunk, '-');

      const headingRuns = [new TextRun({ text: scriptureHeading, bold: true, size: 28, color: DOCX_ACCENT, font: DOCX_HEADING_FONT })];
      if (chunk.episodeNumber || chunk.episodeTitle) {
        headingRuns.push(new TextRun({
          text: `   (Session ${chunk.episodeNumber || '—'}${chunk.episodeTitle ? `: ${chunk.episodeTitle}` : ''})`,
          italics: true,
          size: 22,
          color: '7A7060',
        }));
      }
      children.push(new Paragraph({ children: headingRuns, spacing: { before: 320, after: 120 } }));

      // Scripture text in a left-bordered table cell for a "callout" look (no fill)
      const scriptureParas = getChunkVerseEntries(project, chapterIndex, chunk).map((verse) => new Paragraph({
        children: [
          new TextRun({ text: `${verse.chapter}:${verse.number} `, bold: true, color: DOCX_ACCENT }),
          new TextRun({ text: verse.text, italics: true }),
        ],
        spacing: { after: 80 },
      }));
      children.push(new Table({
        width: { size: 100, type: WidthType.PERCENTAGE },
        rows: [
          new TableRow({
            children: [
              new TableCell({
                margins: { top: 120, bottom: 120, left: 180, right: 180 },
                borders: {
                  ...{ top: noBorder, right: noBorder, bottom: noBorder },
                  left: { style: BorderStyle.SINGLE, size: 24, color: DOCX_ACCENT },
                },
                children: scriptureParas,
              }),
            ],
          }),
        ],
      }));
      children.push(new Paragraph({ text: '', spacing: { after: 120 } }));

      if (chunk.generalNotes?.trim()) {
        children.push(sectionLabel('Background / General Notes'));
        children.push(...createParagraphsFromText(chunk.generalNotes));
      }

      children.push(sectionLabel('Observation'));
      children.push(...createParagraphsFromText(chunk.observation || 'No observation.'));
      children.push(sectionLabel('Interpretation'));
      children.push(...createParagraphsFromText(chunk.interpretation || 'No interpretation.'));
      children.push(sectionLabel('Application'));
      children.push(...createParagraphsFromText(chunk.application || 'No application.'));

      if ((chunk.tags ?? []).length > 0) {
        children.push(sectionLabel('Tags'));
        children.push(new Paragraph({
          children: chunk.tags.map((tag, i) => new TextRun({
            text: i === 0 ? `#${tag}` : `   #${tag}`,
            bold: true,
            color: DOCX_ACCENT,
          })),
        }));
      }

      if ((chunk.crossReferences ?? []).length > 0) {
        children.push(sectionLabel('Cross-References'));
        children.push(new Paragraph({ text: chunk.crossReferences.join('  •  ') }));
      }

      if (chunk.greekWords.length > 0) {
        children.push(sectionLabel('Word Studies'));
        const headerCellStyle = (label) => new TableCell({
          width: { size: 20, type: WidthType.PERCENTAGE },
          borders: { bottom: { style: BorderStyle.SINGLE, size: 8, color: DOCX_ACCENT } },
          children: [new Paragraph({ children: [new TextRun({ text: label, bold: true, color: DOCX_ACCENT })] })],
        });
        const tableRows = [
          new TableRow({
            tableHeader: true,
            children: ['Strong', 'Greek', 'Transliteration', 'Part of Speech', 'Short Definition'].map(headerCellStyle),
          }),
          ...chunk.greekWords.map((word) => new TableRow({
            children: [
              new TableCell({ children: [new Paragraph(word.strongNumber || '')] }),
              new TableCell({ children: [new Paragraph(word.lexeme || '')] }),
              new TableCell({ children: [new Paragraph(word.transliteration || '')] }),
              new TableCell({ children: [new Paragraph(word.partOfSpeech || '')] }),
              new TableCell({ children: [new Paragraph(word.shortDefinition || '')] }),
            ],
          })),
        ];
        children.push(new Table({ rows: tableRows, width: { size: 100, type: WidthType.PERCENTAGE } }));
        chunk.greekWords.forEach((word) => {
          if (word.definitionHtml) {
            children.push(new Paragraph({
              spacing: { before: 180, after: 80 },
              children: [new TextRun({ text: `${word.strongNumber} — ${word.lexeme || ''}`, bold: true, color: DOCX_ACCENT })],
            }));
            children.push(...createParagraphsFromText(htmlToPlainText(word.definitionHtml)));
          }
        });
      }

      if (chunk.finalScript?.trim()) {
        children.push(sectionLabel('Final Script'));
        children.push(...createParagraphsFromText(chunk.finalScript));
      }

      children.push(new Paragraph({
        text: '',
        spacing: { after: 200 },
        border: { bottom: { style: BorderStyle.SINGLE, size: 4, color: '2A2518', space: 8 } },
      }));
    });
  });

  const doc = new Document({
    styles: {
      default: {
        document: { run: { font: DOCX_BODY_FONT, color: '0A0A08' } },
      },
      paragraphStyles: [
        {
          id: 'Title',
          name: 'Title',
          basedOn: 'Normal',
          next: 'Normal',
          run: { font: DOCX_HEADING_FONT, size: 56, bold: true, color: '0A0A08' },
        },
        {
          id: 'Heading1',
          name: 'Heading 1',
          basedOn: 'Normal',
          next: 'Normal',
          run: { font: DOCX_HEADING_FONT, size: 36, bold: true, color: '0A0A08' },
        },
        {
          id: 'Heading2',
          name: 'Heading 2',
          basedOn: 'Normal',
          next: 'Normal',
          run: { font: DOCX_HEADING_FONT, size: 30, bold: true, color: '0A0A08' },
        },
      ],
    },
    sections: [{ children }],
  });
  return Packer.toBlob(doc);
}