import type {
    SvgNode,
    SvgPlugin,
    SvgPluginOptions,
} from "../../types/common.js";

export const collapseGroups: SvgPlugin = {
    name: "collapseGroups",
    apply(node: SvgNode, _options: SvgPluginOptions): SvgNode | null {
        if (node.type !== "element" || node.name !== "g") return node;
        const children = node.children ?? [];
        if (children.length !== 1) return node;

        const child = children[0]!;
        if (child.type !== "element") return node;

        const groupAttrs = node.attributes ?? {};

        // Never collapse if group has an id (may be referenced)
        if ("id" in groupAttrs) return node;

        const childAttrs = child.attributes ?? {};

        // Check for conflicting attributes
        for (const key of Object.keys(groupAttrs)) {
            if (key in childAttrs) return node;
        }

        // Merge group attrs onto child
        return {
            ...child,
            attributes: { ...groupAttrs, ...childAttrs },
        };
    },
};