// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

import {IMAGE_MAX_HEIGHT} from '@constants/image';
import {calculateDimensions} from '@utils/images';

/** Preset caps loosely aligned with Adaptive Cards `Image` sizes; `stretch` matches legacy attachment `image_url`. */
export const MM_IMAGE_SIZE_CAPS: Record<MmImageSize, {maxWidth: number; maxHeight: number} | null> = {
    auto: null,
    xsmall: {maxWidth: 108, maxHeight: 64},
    small: {maxWidth: 204, maxHeight: 120},
    medium: {maxWidth: 320, maxHeight: 184},
    large: {maxWidth: 428, maxHeight: 240},
    stretch: {maxWidth: 500, maxHeight: 350},
};

export function resolveMmImageCaps(block: MmImageBlock): {maxWidth?: number; maxHeight?: number} {
    const size = block.size ?? 'stretch';
    const preset = MM_IMAGE_SIZE_CAPS[size];
    const maxWidth = block.max_width ?? preset?.maxWidth;
    const maxHeight = block.max_height ?? preset?.maxHeight;
    if (size === 'auto' && block.max_width === undefined && block.max_height === undefined) {
        return {};
    }
    const out: {maxWidth?: number; maxHeight?: number} = {};
    if (maxWidth !== undefined) {
        out.maxWidth = maxWidth;
    }
    if (maxHeight !== undefined) {
        out.maxHeight = maxHeight;
    }
    return out;
}

export type MmBlocksImageLayout = {
    width: number;
    height: number;
    galleryWidth: number;
    galleryHeight: number;
};

export function computeMmBlocksImageLayout(
    caps: {maxWidth?: number; maxHeight?: number},
    layoutWidth: number | undefined,
    metadata: PostImage | undefined,
    viewPortWidth: number,
): MmBlocksImageLayout {
    const viewport = layoutWidth ? Math.min(layoutWidth, viewPortWidth) : viewPortWidth;
    const maxW = caps.maxWidth ?? viewport;
    const maxH = caps.maxHeight ?? IMAGE_MAX_HEIGHT;

    if (metadata?.width && metadata?.height) {
        const {width, height} = calculateDimensions(
            metadata.height,
            metadata.width,
            Math.min(viewport, maxW),
            maxH,
        );
        return {
            width,
            height,
            galleryWidth: metadata.width,
            galleryHeight: metadata.height,
        };
    }

    const width = Math.min(maxW, viewport);
    const height = Math.min(maxH, Math.round(width * 0.75));
    return {
        width,
        height,
        galleryWidth: width,
        galleryHeight: height,
    };
}

export function refineMmBlocksImageLayoutFromIntrinsic(
    intrinsicWidth: number,
    intrinsicHeight: number,
    caps: {maxWidth?: number; maxHeight?: number},
    layoutWidth: number | undefined,
    viewPortWidth: number,
): MmBlocksImageLayout {
    const viewport = layoutWidth ? Math.min(layoutWidth, viewPortWidth) : viewPortWidth;
    const maxW = caps.maxWidth ?? viewport;
    const maxH = caps.maxHeight ?? IMAGE_MAX_HEIGHT;
    const {width, height} = calculateDimensions(
        intrinsicHeight,
        intrinsicWidth,
        Math.min(viewport, maxW),
        maxH,
    );
    return {
        width,
        height,
        galleryWidth: intrinsicWidth,
        galleryHeight: intrinsicHeight,
    };
}