import type { CpNode } from '../cp-node/cp-node.js';
import { getBranch } from '../cp-node/fs/get-branch.js';
import { getNonTerminatingOnCircle } from '../cp-node/fs/get-non-terminating-on-circle.js';


/**
 * Returns all branches associated with the give cpNode.
 * 
 * * the final `CpNode` of each branch is not returned to improve symmetry
 * 
 * @param cpNode `CpNode` representing the start vertex.
 */
function getBranches(
        cpNode: CpNode): CpNode[][] {

    const branches: CpNode[][] = [];
    const cpNodeStack: CpNode[] = [cpNode];
    const takenBranches: Set<CpNode> = new Set();
    while (cpNodeStack.length > 0) {
        const cpNode = cpNodeStack.pop()!;
        const branch = getBranch(cpNode);

        if (branch.length === 0) { continue; }

        branches.push(branch);

        const cpNodeS = branch[0];
        const cpNodeE = branch[branch.length-1].next.prevOnCircle;

        takenBranches.add(cpNodeS);
        takenBranches.add(cpNodeE);

        const _cpNodesS = getNonTerminatingOnCircle(cpNodeS, true);
        const _cpNodesE = getNonTerminatingOnCircle(cpNodeE, true);
        const cpNodesS = _cpNodesS.filter(cpNode => !takenBranches.has(cpNode));
        const cpNodesE = _cpNodesE.filter(cpNode => !takenBranches.has(cpNode));

        for (const cpNode of cpNodesS) {
            takenBranches.add(cpNode);
        }
        for (const cpNode of cpNodesE) {
            takenBranches.add(cpNode);
        }

        cpNodeStack.push(...cpNodesS, ...cpNodesE);
    }

    return branches;
}


export { getBranches }