class Annotation {
    createAnnotations(document) {
        const annotations = [];

        document.elements.forEach((element) => {
            console.log("Creating annotation for element", element.id)

            const [annotation, formField] = this.createAnnotationFromElement(element)
            annotations.push(annotation);
            annotations.push(formField);
        })

        return annotations;
    }

    async deleteAnnotations(instance) {
        let pageAnnotations = (
            await Promise.all(Array.from({ length: instance.totalPageCount }).map((_, pageIndex) =>
                instance.getAnnotations(pageIndex)
            ))
        ).flatMap((annotations) =>
            annotations.reduce((acc, annotation) => acc.concat(annotation), [])
        ).filter((annotation) => !!annotation.isSignature || annotation.description == "FRAME");
        //deleting all Annotations
        return await instance.delete(pageAnnotations);
    }

    async validateAnnotations(instance) {
        let pageAnnotations = (
            await Promise.all(Array.from({ length: instance.totalPageCount }).map((_, pageIndex) =>
                instance.getAnnotations(pageIndex)
            ))
        ).flatMap((annotations) =>
            annotations.reduce((acc, annotation) => acc.concat(annotation), [])
        ).map((annotation) => {
            console.log(annotation.toJS());
            return annotation;
        });

        return true;
    }

    createAnnotationFromElement(element) {
        const id = PSPDFKit.generateInstantId()
        const width = this.inchToPoint(element.width)
        const height = this.inchToPoint(element.height)
        const top = this.inchToPoint(element.top) - (height / 2)
        const left = this.inchToPoint(element.left) - (width / 2)
        const page = element.page - 1
        const annotation = this.createSignatureAnnotation(id, width, height, top, left, page)
        console.log(annotation)

        const formField = new PSPDFKit.FormFields.SignatureFormField({
            name: id,
            annotationIds: PSPDFKit.Immutable.List([annotation.id])
        })
        console.log(formField)

        return [annotation, formField]
    }

    createSignatureAnnotation(id, width, height, top, left, pageIndex) {
        const annotation = new PSPDFKit.Annotations.WidgetAnnotation({
            id: id,
            pageIndex: pageIndex,
            formFieldName: id,
            boundingBox: new PSPDFKit.Geometry.Rect({ width, height, top, left })
        })

        return annotation
    }

    async createAnnotationFrameBlob(receiverName, width, height) {
        const canvas = document.createElement("canvas");
        canvas.width = width;
        canvas.height = height;

        const ctx = canvas.getContext("2d");

        const date = new Date();
        const dateString = date.toLocaleDateString("de-DE");

        const signatureLength = 100;

        ctx.beginPath();

        ctx.moveTo(30, 10);
        ctx.lineTo(signatureLength, 10);

        ctx.moveTo(30, 10);
        ctx.arcTo(10, 10, 10, 30, 20);

        ctx.moveTo(10, 30);
        ctx.arcTo(10, 50, 30, 50, 20);

        ctx.moveTo(30, 50);
        ctx.lineTo(signatureLength, 50);

        ctx.strokeStyle = "darkblue";
        ctx.stroke();

        ctx.fillStyle = "black";
        ctx.font = "10px serif";
        ctx.fillText("Signed by", 30, 10)
        ctx.fillText(receiverName + ", " + dateString, 15, 60)

        return new Promise(resolve => {
            canvas.toBlob((blob) => {
                const url = URL.createObjectURL(blob);
                resolve(url)      
            })
        })
    }

    inchToPoint(inch) {
        return inch * 72;
    }
}