import type { LawXMLStruct } from "../../../data/loaders/common";
import { imageSize } from "image-size";
import type { DOCXFigData, DOCXFigDataManager, DOCXFigEmbedFile, DOCXFigImageFile } from "./component";
import * as std from "../../../law/std";
import type { EL } from "../../../node/el";
import { decodeBase64 } from "../../../util";
import { getPdfjs } from "./getPdfjs";

function *iterateFig(el: EL): IterableIterator<std.Fig> {
    if (std.isFig(el)) yield el;
    for (const c of el.children) {
        if (typeof c === "string") continue;
        yield* iterateFig(c);
    }
}

const createCanvas = async (width: number, height: number) => {
    return (
        global.OffscreenCanvas
            ? new OffscreenCanvas(width, height)
            : (new (await import("canvas")).Canvas(width, height))
    );
};

export const pdfToPNG = async (pdfData: ArrayBuffer) => {
    const pdfjs = await getPdfjs();
    const pngs: {buf: ArrayBuffer, width: number, height: number, pageNumber: number}[] = [];
    const pdfTask = pdfjs.getDocument({ data: pdfData.slice(0) });
    const pdf = await pdfTask.promise;
    for (let i = 0; i < pdf.numPages; i++) {
        const page = await pdf.getPage(i + 1);
        const viewport = page.getViewport({ scale: 3 });
        const canvas = await createCanvas(viewport.width, viewport.height);
        const context = canvas.getContext("2d");
        if (!context) {
            console.error("pdfToPNG: Unexpected empty context");
            continue;
        }
        await page.render({
            canvasContext: context as unknown as CanvasRenderingContext2D,
            viewport,
            background: "white",
        }).promise;

        const buf = (
            ("convertToBlob" in canvas)
                ? await (await canvas.convertToBlob()).arrayBuffer()
                : canvas.toBuffer()
        );

        pngs.push({
            buf,
            width: canvas.width,
            height: canvas.height,
            pageNumber: i + 1,
        });

    }
    return pngs;
};

export const pdfPageCXMax = 5364000;
export const pdfPageCYMax = 8000000;

export const figPDFTypes = ["srcText", "embed", "render", "embedAndRender"] as const;

export interface FigDataManagerOptions {
    lawXMLStruct: LawXMLStruct,
    subsetLaw: EL,
    figPDFType?: (typeof figPDFTypes)[number],
    onProgress?: (info: {current: number, length: number, item: string}) => unknown,
}

export class FigDataManager implements DOCXFigDataManager {
    pdfIcon = {
        rId: "rPdfIcon",
        buf: decodeBase64(pdfIconBinaryBase64),
        fileName: "pdfIcon.emf",
    };
    constructor(
        public figDataMap: Map<string, DOCXFigData>,
    ) { }
    static async create(options: FigDataManagerOptions) {
        const {
            lawXMLStruct,
            subsetLaw,
            figPDFType,
            onProgress,
        } = {
            figPDFType: "embed" as const,
            ...options,
        };
        let counter = 0;
        const figDataMap: Map<string, DOCXFigData> = new Map();

        if (figPDFType === "srcText") {
            //
        } else {
            const figs = [...iterateFig(subsetLaw)];
            for (const [current, el] of figs.entries()) {
                if (onProgress) onProgress({ current, length: figs.length, item: el.attr.src });
                const src = el.attr.src;
                const blob = await lawXMLStruct.getPictBlob(src);
                if (!blob) continue;

                if (blob.type === "application/pdf") {
                    const file: DOCXFigEmbedFile | null = (
                        (figPDFType === "embed" || figPDFType === "embedAndRender")
                            ? {
                                id: 1000000 + counter,
                                rId: `fig${counter + 1}`,
                                name: src.split("/").slice(-1)[0],
                                blob,
                            }
                            : null
                    );
                    counter++;
                    const pages: DOCXFigImageFile[] | null = (
                        (figPDFType === "render" || figPDFType === "embedAndRender")
                            ? (await pdfToPNG(blob.buf)).map(({ buf, width, height, pageNumber }, i) => {
                                const cScale = Math.min(
                                    (Math.min(width * 9525, pdfPageCXMax) / (width * 9525)),
                                    (Math.min(height * 9525, pdfPageCYMax) / (height * 9525)),
                                );
                                return {
                                    id: 1000000 + counter + i,
                                    rId: `fig${counter + 1 + i}`,
                                    cx: Math.round(width * 9525 * cScale),
                                    cy: Math.round(height * 9525 * cScale),
                                    name: `${src.split("/").slice(-1)[0]}.page${pageNumber}.png`,
                                    blob: {
                                        buf,
                                        type: "image/png",
                                    },
                                };
                            })
                            : null
                    );

                    if (pages)counter += pages.length;

                    if (file) {
                        if (pages) {
                            figDataMap.set(src, { src, type: "embeddedAndRenderedPDF", file, pages });
                        } else {
                            figDataMap.set(src, { src, type: "embeddedPDF", file });
                        }
                    } else {
                        if (pages) {
                            figDataMap.set(src, { src, type: "renderedPDF", pages });
                        } else {
                            console.error("FigDataManager.create: Unexpected empty file and pages");
                        }
                    }

                } else {
                    const size = (() => {
                        try {
                            return imageSize(new Uint8Array(blob.buf));
                        } catch {
                            return null;
                        }
                    })();
                    try {
                        figDataMap.set(src, {
                            type: "image",
                            src,
                            image: {
                                id: 1000000 + counter,
                                rId: `fig${counter + 1}`,
                                cx: (size?.width ?? 100) * 9525,
                                cy: (size?.height ?? 141) * 9525,
                                name: src.split("/").slice(-1)[0],
                                blob,
                            },
                        });
                        counter++;
                    } catch {
                        //
                    }
                }
            }
        }
        return new FigDataManager(figDataMap);
    }
    getFigData(src: string): DOCXFigData | null {
        return this.figDataMap.get(src) ?? null;
    }
    getFigDataItems(): [src: string, figData: DOCXFigData][] {
        return [...this.figDataMap.entries()];
    }
}

export default FigDataManager;

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