import type { DiagramIRV2 } from "../../model/diagram-ir.js";
import { validateDiagramIR } from "../../model/diagram-ir.js";

export interface ArchitectureSnapshot { id: string; label: string; ir: DiagramIRV2; provenance?: Record<string, unknown> }
export interface ChangeSet { added: string[]; removed: string[]; modified: string[]; unchanged: string[] }
export interface TimelapseFrame { id: string; label: string; index: number; ir: DiagramIRV2; changes: { nodes: ChangeSet; edges: ChangeSet }; provenance?: Record<string, unknown> }
export interface ArchitectureTimelapse { frames: TimelapseFrame[] }

function canonical(value: unknown): string {
  if (Array.isArray(value)) return `[${value.map(canonical).join(",")}]`;
  if (value && typeof value === "object") return `{${Object.entries(value as Record<string, unknown>).sort(([a], [b]) => a.localeCompare(b)).map(([key, item]) => `${JSON.stringify(key)}:${canonical(item)}`).join(",")}}`;
  return JSON.stringify(value);
}
function inventory(ir: DiagramIRV2, kind: "nodes" | "edges"): Map<string, unknown> {
  return new Map(ir.pages.flatMap((page) => page[kind].map((item) => [`${page.id}/${item.id}`, item] as const)));
}
function classify(previous: Map<string, unknown>, current: Map<string, unknown>): ChangeSet {
  const added: string[] = [], removed: string[] = [], modified: string[] = [], unchanged: string[] = [];
  for (const id of [...current.keys()].sort()) {
    if (!previous.has(id)) added.push(id); else if (canonical(previous.get(id)) === canonical(current.get(id))) unchanged.push(id); else modified.push(id);
  }
  for (const id of [...previous.keys()].sort()) if (!current.has(id)) removed.push(id);
  return { added, removed, modified, unchanged };
}

export function createArchitectureTimelapse(snapshots: readonly ArchitectureSnapshot[]): ArchitectureTimelapse {
  if (!Array.isArray(snapshots) || snapshots.length === 0) throw new Error("Timelapse requires at least one snapshot");
  const ids = new Set(snapshots.map((snapshot) => snapshot.id)); if (ids.size !== snapshots.length) throw new Error("Snapshot IDs must be unique");
  let previousNodes = new Map<string, unknown>(), previousEdges = new Map<string, unknown>();
  const frames = snapshots.map((snapshot, index) => {
    const ir = structuredClone(snapshot.ir); validateDiagramIR(ir);
    const currentNodes = inventory(ir, "nodes"), currentEdges = inventory(ir, "edges");
    const frame: TimelapseFrame = { id: snapshot.id, label: snapshot.label, index, ir, changes: { nodes: classify(previousNodes, currentNodes), edges: classify(previousEdges, currentEdges) }, provenance: snapshot.provenance === undefined ? undefined : structuredClone(snapshot.provenance) };
    previousNodes = currentNodes; previousEdges = currentEdges; return frame;
  });
  return { frames };
}