package com.megatim.manuel.core.convert;

import org.apache.poi.sl.usermodel.Placeholder;
import org.apache.poi.xslf.usermodel.XMLSlideShow;
import org.apache.poi.xslf.usermodel.XSLFShape;
import org.apache.poi.xslf.usermodel.XSLFSlide;
import org.apache.poi.xslf.usermodel.XSLFTextShape;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.file.Path;
import java.util.ArrayList;
import java.util.List;

/**
 * PowerPoint .pptx (XSLF) -> HTML : chaque diapositive est rendue en image PNG (rendu fidèle),
 * et son titre devient une entrée de la table des matières.
 */
public class PptxConverter extends AbstractHtmlConverter {

    private static final double SCALE = 2.0;

    public PptxConverter(Path outputDir) {
        super(outputDir);
    }

    @Override
    public ConversionResult convert(Path source, int order) throws IOException {
        String safe = safeBase(source, order);
        String htmlName = safe + ".html";
        List<Heading> headings = new ArrayList<>();
        List<String> images = new ArrayList<>();
        StringBuilder body = new StringBuilder();

        try (FileInputStream fis = new FileInputStream(source.toFile());
             XMLSlideShow ppt = new XMLSlideShow(fis)) {

            Dimension d = ppt.getPageSize();
            int w = (int) Math.round(d.width * SCALE);
            int h = (int) Math.round(d.height * SCALE);

            int n = 0;
            for (XSLFSlide slide : ppt.getSlides()) {
                n++;
                String title = slideTitle(slide, n);

                BufferedImage img = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
                Graphics2D g = img.createGraphics();
                applyQualityHints(g);
                g.setColor(Color.WHITE);
                g.fillRect(0, 0, w, h);
                g.scale(SCALE, SCALE);
                try {
                    slide.draw(g);
                } finally {
                    g.dispose();
                }

                String imgName = writeImagePng(safe, n, img);
                images.add(imgName);

                String anchor = safe + "_s" + n;
                headings.add(new Heading(title, 1, anchor));
                body.append("<h1 id=\"").append(anchor).append("\">").append(esc(title)).append("</h1>\n");
                body.append("<p class=\"slide\"><img src=\"").append(imgName)
                    .append("\" alt=\"").append(esc(title)).append("\"/></p>\n");
            }
        }

        String docTitle = headings.isEmpty() ? stripExt(source.getFileName().toString()) : headings.get(0).text;
        writeHtml(htmlName, docTitle, body.toString());
        return new ConversionResult(htmlName, docTitle, headings, images);
    }

    private String slideTitle(XSLFSlide slide, int n) {
        try {
            for (XSLFShape sh : slide.getShapes()) {
                if (sh instanceof XSLFTextShape) {
                    XSLFTextShape ts = (XSLFTextShape) sh;
                    Placeholder ph = ts.getPlaceholder();
                    if (ph == Placeholder.TITLE || ph == Placeholder.CENTERED_TITLE) {
                        String t = ts.getText();
                        if (t != null && !t.isBlank()) return t.trim();
                    }
                }
            }
        } catch (Exception ignore) { /* pas de titre exploitable */ }
        return "Diapositive " + n;
    }
}