import source photonWasm from "photon_wasm";
import * as photon from "photon";
// arbitrary limits concerning the photo size and dimensions
// they are NOT enforced strictly enough!
const maxBytes = 10 * 1024 * 1024; // 10 MiB = 10,485,760 bytes
const maxPixels = 16000000;        // 16 megapixels
// ...
/**
 * Looks up a photo by primary key and returns and logs its decoded statistics.
 * Statistics describe Photon's RGBA8 pixels, not the source encoding's color
 * depth or metadata. Releases the decoded WASM image before returning.
 *
 * @param {string} id - uploaded_files ID represented as a string that converts
 *   to a positive JavaScript safe integer. ORDS provides variables as strings!
 * @returns {PhotoDetails} Decoded dimensions, sizes, color and pixel statistics.
 * @throws {Error} If the ID is invalid, the row is missing, the BLOB is empty,
 *   or database access, validation or decoding fails.
 */
export function photoDetails(id) {
    if (!id || typeof id !== 'string') {
        throw new Error('photoDetails() requires the ID to be a string');
    }
    // A safe integer avoids precision loss when binding the JavaScript number.
    const numericId = Number(id.trim());
    if (!Number.isSafeInteger(numericId) || numericId <= 0) {
        throw new Error('you must provide an ID greater than 0 to photoDetails()');
    }
    const result = session.execute(
        "select file_content from uploaded_files where id = :id",
        { id: { val: numericId, dir: oracledb.BIND_IN, type: oracledb.NUMBER } }
    );
    if (result.rows.length === 0) {
        throw new Error(`No photo found for ID ${id}`);
    }
    const photoBlob = result.rows[0].FILE_CONTENT;
    if (photoBlob === null || photoBlob === undefined) {
        throw new Error(`The photo BLOB with id ${id} is empty`);
    }
    // TODO: check photoBlob.length() before copying the BLOB into JavaScript.
    const bytes = photoBlob.getData();
    if (bytes.length === 0) {
        throw new Error(`The photo BLOB with id ${id} is empty`);
    }
    // TODO: size and filename are not defined in this function. This currently
    // throws ReferenceError for a nonempty BLOB. Use the BLOB length and id,
    // and move the size check above getData() to enforce it before the copy.
    if (size > maxBytes) {
        throw new Error(`The uploaded file ${filename} exceeds the 10 MiB size limit`);
    }
    // this is where the WebAssembly module is initialised. The following JavaScript
    // code calls the JS bindings, not Wasm directly. You can find the documentation
    // here: https://docs.rs/photon-rs/latest/photon_rs/index.html
    photon.initSync({ module: photonWasm });
    const image = photon.PhotonImage.new_from_byteslice(bytes);
    // TODO: enforce the 16 megapixel limit before decoding, with a second
    // check afterward before copying the decoded pixel array.
    try {
        const width = image.get_width();
        const height = image.get_height();
        // Copies RGBA8 pixels out of WASM; source bit depth is not retained.
        const pixels = image.get_raw_pixels();
        const pixelCount = width * height;
        let hasTransparency = false;
        let isGrayscale = true;
        let red = 0;
        let green = 0;
        let blue = 0;
        // Each pixel occupies four consecutive bytes: red, green, blue, alpha.
        for (let i = 0; i < pixels.length; i += 4) {
            red += pixels[i];
            green += pixels[i + 1];
            blue += pixels[i + 2];
            if (pixels[i + 3] < 255) hasTransparency = true;
            if (pixels[i] !== pixels[i + 1] || pixels[i] !== pixels[i + 2]) {
                isGrayscale = false;
            }
        }
        const details = {
            width,
            height,
            aspect_ratio: width / height,
            orientation: width === height ? "square" : width > height ? "landscape" : "portrait",
            pixel_count: pixelCount,
            megapixels: pixelCount / 1000000,
            file_size_bytes: bytes.length,
            decoded_size_bytes: pixels.length,
            color_model: "RGBA",
            channels: 4,
            bits_per_channel: 8,
            bits_per_pixel: 32,
            has_transparency: hasTransparency,
            is_grayscale: isGrayscale,
            // Arithmetic mean of all decoded pixels, including transparent ones.
            average_rgb: {
                red: red / pixelCount,
                green: green / pixelCount,
                blue: blue / pixelCount
            }
        };
        // Emits derived image statistics to the host's JavaScript log output.
        console.log(JSON.stringify(details, null, 2));
        return details;
    } finally {
        image.free();
    }
};
// ...