import { Document, Packer, Paragraph, TextRun, HeadingLevel, Table, TableRow, TableCell, WidthType, ShadingType, AlignmentType, BorderStyle, Header, ImageRun } from 'docx';
import { saveAs } from 'file-saver';

/**
 * Exports structured JSON content to a .docx file.
 * @param {Array} elements - The structured document elements.
 * @param {string} filename - The name of the file to save.
 */
/**
 * Parses markdown-style text (bold/italic) into docx TextRun objects.
 * @param {string} text 
 * @returns {TextRun[]}
 */
const parseRichText = (text, options = {}) => {
    const defaultOptions = { font: "Times New Roman", size: 22, ...options };
    if (typeof text !== 'string') return [new TextRun({ text: String(text), ...defaultOptions })];
    const parts = [];
    const regex = /(\*\*.*?\*\*|\*.*?\*)/g;
    let lastIndex = 0;
    let match;

    while ((match = regex.exec(text)) !== null) {
        if (match.index > lastIndex) {
            parts.push(new TextRun({ text: text.substring(lastIndex, match.index), ...defaultOptions }));
        }
        const content = match[0];
        if (content.startsWith('**')) {
            parts.push(new TextRun({ text: content.slice(2, -2), bold: true, ...defaultOptions }));
        } else if (content.startsWith('*')) {
            parts.push(new TextRun({ text: content.slice(1, -1), italics: true, ...defaultOptions }));
        }
        lastIndex = regex.lastIndex;
    }

    if (lastIndex < text.length) {
        parts.push(new TextRun({ text: text.substring(lastIndex), ...defaultOptions }));
    }

    return parts.length > 0 ? parts : [new TextRun({ text, ...defaultOptions })];
};

const stripPrefix = (text) => {
    if (typeof text !== 'string') return text;
    return text.replace(/^(\([a-zA-Z0-9]+\)|[a-zA-Z0-9]+[\.\)]|[\-\•])\s*/, '');
};

export const exportToDocx = async (elements, filename = 'Formatted_Document.docx', docType = 'rfp', logoBase64 = null, contractAddress = '') => {
    const isRfp = docType === 'rfp';
    const children = elements.map(el => {
        const align = el.alignment === 'center' ? AlignmentType.CENTER : AlignmentType.LEFT;
        switch (el.type) {
            case 'heading1':
                return new Paragraph({
                    children: parseRichText(el.content, { color: '000000', bold: true, size: 22 }),
                    shading: isRfp ? {
                        fill: 'FFC000',
                        type: ShadingType.CLEAR,
                        color: 'auto',
                    } : undefined,
                    spacing: {
                        before: isRfp ? 240 : 480,
                        after: isRfp ? 200 : 320,
                    },
                    alignment: align,
                });
            case 'heading2':
                return new Paragraph({
                    children: parseRichText(el.content, { size: 22, bold: true, color: '000000' }),
                    spacing: {
                        before: isRfp ? 200 : 400,
                        after: isRfp ? 160 : 240
                    },
                    alignment: align,
                });
            case 'heading3':
                return new Paragraph({
                    children: parseRichText(el.content, { size: 22, bold: true, italics: true, color: '000000' }),
                    spacing: {
                        before: isRfp ? 160 : 320,
                        after: isRfp ? 120 : 200
                    },
                    alignment: align,
                });
            case 'bulletList':
                return el.content.map(item => new Paragraph({
                    children: parseRichText(stripPrefix(item)),
                    bullet: { level: 0 },
                    indent: { left: 720, hanging: 360 },
                    spacing: {
                        before: isRfp ? 40 : 80,
                        after: isRfp ? 40 : 80
                    },
                    alignment: align,
                }));
            case 'numberedList':
                return el.content.map(item => new Paragraph({
                    children: parseRichText(stripPrefix(item)),
                    numbering: {
                        reference: 'main-numbering',
                        level: el.listType === 'lowerAlpha' ? 1 : 0
                    },
                    indent: {
                        left: el.listType === 'lowerAlpha' ? 1440 : 720,
                        hanging: 360
                    },
                    spacing: {
                        before: isRfp ? 40 : 80,
                        after: isRfp ? 40 : 80
                    },
                    alignment: align,
                }));
            case 'table':
                return new Table({
                    width: {
                        size: 100,
                        type: WidthType.PERCENTAGE,
                    },
                    rows: el.content.map(row =>
                        new TableRow({
                            children: row.map(cell =>
                                new TableCell({
                                    children: [new Paragraph({
                                        children: parseRichText(cell, { size: 22 }),
                                        spacing: { line: 360 } // 1.5 line spacing
                                    })],
                                    borders: {
                                        top: { style: BorderStyle.SINGLE, size: 2 },
                                        bottom: { style: BorderStyle.SINGLE, size: 2 },
                                        left: { style: BorderStyle.SINGLE, size: 2 },
                                        right: { style: BorderStyle.SINGLE, size: 2 },
                                    },
                                    margins: {
                                        top: 100,
                                        bottom: 100,
                                        left: 100,
                                        right: 100,
                                    },
                                    shading: {
                                        fill: 'FFFFFF',
                                        type: ShadingType.CLEAR,
                                        color: 'auto',
                                    }
                                })
                            )
                        })
                    ),
                });
            case 'paragraph':
            default:
                return new Paragraph({
                    children: parseRichText(el.content),
                    spacing: {
                        before: isRfp ? 120 : 240,
                        after: isRfp ? 120 : 240,
                        line: 360 // 1.5 line spacing
                    },
                    alignment: align,
                });
        }
    }).flat();

    const doc = new Document({
        numbering: {
            config: [
                {
                    reference: "main-numbering",
                    levels: [
                        {
                            level: 0,
                            format: "decimal",
                            text: "%1.",
                            alignment: AlignmentType.LEFT,
                            style: {
                                paragraph: {
                                    indent: { left: 720, hanging: 360 } /* 0.5" left, 0.25" hanging */
                                }
                            }
                        },
                        {
                            level: 1,
                            format: "lowerLetter",
                            text: "%2.",
                            alignment: AlignmentType.LEFT,
                            style: {
                                paragraph: {
                                    indent: { left: 1440, hanging: 360 } /* 1.0" left, 0.25" hanging */
                                }
                            }
                        },
                    ],
                },
            ],
        },
        sections: [{
            properties: {},
            headers: {
                default: new Header({
                    children: [
                        new Table({
                            width: {
                                size: 100,
                                type: WidthType.PERCENTAGE,
                            },
                            borders: {
                                top: { style: BorderStyle.NONE },
                                bottom: { style: BorderStyle.NONE },
                                left: { style: BorderStyle.NONE },
                                right: { style: BorderStyle.NONE },
                                insideVertical: { style: BorderStyle.NONE },
                                insideHorizontal: { style: BorderStyle.NONE },
                            },
                            rows: [
                                new TableRow({
                                    children: [
                                        new TableCell({
                                            width: { size: 35, type: WidthType.PERCENTAGE },
                                            children: logoBase64 ? [
                                                new Paragraph({
                                                    children: [
                                                        new ImageRun({
                                                            data: Uint8Array.from(atob(logoBase64.split(',')[1]), c => c.charCodeAt(0)),
                                                            transformation: {
                                                                width: 150,
                                                                height: 50,
                                                            },
                                                        }),
                                                    ],
                                                    alignment: AlignmentType.LEFT,
                                                })
                                            ] : [new Paragraph({})], // Fallback for empty cell
                                        }),
                                        new TableCell({
                                            width: { size: 65, type: WidthType.PERCENTAGE },
                                            verticalAlign: AlignmentType.CENTER,
                                            children: contractAddress ? [
                                                new Paragraph({
                                                    children: contractAddress.split('\n').map((line, i) =>
                                                        new TextRun({
                                                            text: line,
                                                            font: "Times New Roman",
                                                            size: 20, // 10pt
                                                            color: "000000",
                                                            break: i > 0 ? 1 : 0
                                                        })
                                                    ),
                                                    alignment: AlignmentType.RIGHT,
                                                })
                                            ] : [new Paragraph({})], // Fallback for empty cell
                                        }),
                                    ],
                                }),
                            ],
                        }),
                    ],
                }),
            },
            children: children,
        }],
    });

    const blob = await Packer.toBlob(doc);
    saveAs(blob, filename);
};