/**
 * Onion timeline fork/merge helpers for Path Tracer UI + Seer/AI context.
 */

import { spreadStrainFromJoinLane } from './fleetTopologyEpidemiology';

export type TimelineBranchStatus =
  | 'canonical'
  | 'running'
  | 'won'
  | 'lost'
  | 'merged'
  | 'failed'
  | 'aborted';

export interface PathTraceTimelineBranch {
  id: string;
  parent_id?: string;
  fork_hop_index: number;
  target_agent_id?: string;
  target_agent_name?: string;
  persona?: string;
  spread_lanes?: string[];
  status: TimelineBranchStatus;
  mining_linked?: boolean;
  hashrate?: number;
  active_tier?: string;
  error?: string;
  is_ghost: boolean;
  created_at?: string;
  merged_at?: string;
}

export interface PathTraceTimelineWS {
  session_id: string;
  event: string;
  branch?: PathTraceTimelineBranch;
  branches?: PathTraceTimelineBranch[];
  mermaid?: string;
  target_agent_id?: string;
}

export function branchStatusLabel(status: TimelineBranchStatus): string {
  switch (status) {
    case 'canonical':
      return 'canonical';
    case 'running':
      return 'exploring';
    case 'won':
      return 'mining linked';
    case 'merged':
      return 'merged';
    case 'lost':
      return 'lost';
    case 'failed':
      return 'failed';
    case 'aborted':
      return 'aborted';
    default:
      return status;
  }
}

export function branchStatusClass(status: TimelineBranchStatus): string {
  switch (status) {
    case 'won':
    case 'merged':
      return 'won';
    case 'running':
      return 'running';
    case 'failed':
    case 'lost':
    case 'aborted':
      return 'failed';
    case 'canonical':
      return 'canonical';
    default:
      return 'ghost';
  }
}

/** Ghost branches grouped under fork hop index for tree rendering. */
export function ghostBranchesByHop(branches: PathTraceTimelineBranch[]): Map<number, PathTraceTimelineBranch[]> {
  const map = new Map<number, PathTraceTimelineBranch[]>();
  for (const b of branches) {
    if (!b.is_ghost) continue;
    const list = map.get(b.fork_hop_index) ?? [];
    list.push(b);
    map.set(b.fork_hop_index, list);
  }
  return map;
}

function branchPrimaryLane(branch: PathTraceTimelineBranch): string {
  return branch.spread_lanes?.[0]?.trim() ?? '';
}

/** Spread strain from join lane — mirrors Go SpreadStrainFromJoinLane for hospice guards. */
export function spreadStrainFromPersonaLane(lane: string): string {
  if (!lane) return '';
  return spreadStrainFromJoinLane(lane).toLowerCase();
}

export function pickMergeCandidate(
  branches: PathTraceTimelineBranch[],
  hospiceStrains?: Set<string>,
): PathTraceTimelineBranch | null {
  const hospice = hospiceStrains ?? new Set<string>();
  const eligible = (b: PathTraceTimelineBranch) => {
    const lane = branchPrimaryLane(b);
    if (!lane || hospice.size === 0) return true;
    const strain = spreadStrainFromPersonaLane(lane);
    return strain === '' || !hospice.has(strain);
  };
  const ghosts = branches.filter((b) => b.is_ghost && eligible(b));
  const won = ghosts.find((b) => b.status === 'won' || b.mining_linked);
  if (won) return won;
  const running = ghosts.find((b) => b.status === 'running');
  return running ?? null;
}

export function mergeMermaidStyles(mermaid: string): string {
  const styles = `classDef won fill:#0a3d2e,stroke:#00ffaa,color:#00ffaa
classDef running fill:#3d320a,stroke:#ffc800,color:#ffc800
classDef failed fill:#3d0a0a,stroke:#ff5050,color:#ff5050
classDef ghost fill:#1a1a2e,stroke:#888,color:#ccc`;
  if (mermaid.includes('classDef won')) return mermaid;
  return `${mermaid.trim()}\n${styles}`;
}