import type { TenantDb } from "./db";

/**
 * Ableitung des Abhängigkeitsgraphen (SPEC §4.11) aus Process,
 * ProcessAsset(role), Asset und AssetRelation. Keine redundante
 * Datenhaltung — der Graph wird bei jedem Aufruf frisch berechnet.
 *
 * Kritikalität je Knoten:
 *  - Prozess: BIA-Kritikalität (1–4), sonst 1
 *  - Asset:   max(C, I, A)
 * Kritische Kante: beide Endknoten-Kritikalität ≥ Schwellwert.
 * Kritischer Pfad: von kritischen Prozessen entlang kritischer Kanten (DFS).
 * SPOF: Asset, von dem ≥ spofMin kritische Prozesse (transitiv) abhängen.
 */

export type GraphNodeKind =
  | "process"
  | "INFORMATION"
  | "SYSTEM"
  | "APPLICATION"
  | "LOCATION"
  | "SUPPLIER"
  | "PERSON"
  | "DATA";

export type GraphNode = {
  id: string;
  entity: "process" | "asset";
  kind: GraphNodeKind;
  name: string;
  sub: string | null;
  criticality: number;
  critical: boolean;
  spof: boolean;
  dependentCriticalProcesses: number;
};

export type GraphEdge = {
  id: string;
  source: string;
  target: string;
  label: string;
  critical: boolean;
};

export type DependencyGraph = {
  nodes: GraphNode[];
  edges: GraphEdge[];
  threshold: number;
  analysis: {
    spofs: { id: string; name: string; count: number }[];
    criticalProcessCount: number;
    criticalEdgeCount: number;
    longestCriticalPath: string[]; // Knoten-Namen
  };
};

export async function buildDependencyGraph(
  db: TenantDb,
  opts: { threshold?: number; spofMin?: number } = {}
): Promise<DependencyGraph> {
  const threshold = opts.threshold ?? 3;
  const spofMin = opts.spofMin ?? 2;

  const [processes, assets, relations] = await Promise.all([
    db.process.findMany({
      include: {
        bia: { select: { criticality: true } },
        processAssets: { select: { assetId: true, role: true } },
      },
    }),
    db.asset.findMany({
      select: {
        id: true,
        name: true,
        type: true,
        confidentiality: true,
        integrity: true,
        availability: true,
      },
    }),
    db.assetRelation.findMany({ select: { assetId: true, relatedAssetId: true, type: true } }),
  ]);

  const pid = (id: string) => `p:${id}`;
  const aid = (id: string) => `a:${id}`;

  const assetCrit = new Map<string, number>();
  for (const a of assets) {
    assetCrit.set(a.id, Math.max(a.confidentiality, a.integrity, a.availability));
  }

  const nodes: GraphNode[] = [];
  const critOf = new Map<string, number>();

  for (const p of processes) {
    const c = p.bia?.criticality ?? 1;
    critOf.set(pid(p.id), c);
    nodes.push({
      id: pid(p.id),
      entity: "process",
      kind: "process",
      name: p.name,
      sub: null,
      criticality: c,
      critical: c >= threshold,
      spof: false,
      dependentCriticalProcesses: 0,
    });
  }
  for (const a of assets) {
    const c = assetCrit.get(a.id) ?? 1;
    critOf.set(aid(a.id), c);
    nodes.push({
      id: aid(a.id),
      entity: "asset",
      kind: a.type,
      name: a.name,
      sub: null,
      criticality: c,
      critical: c >= threshold,
      spof: false,
      dependentCriticalProcesses: 0,
    });
  }

  // Zwei Sichten:
  //  - adjacency (Analyse): Abhängigkeitsrichtung (Abhängiger → Abhängigkeit),
  //    Basis für kritischen Pfad, SPOF, transitive Abhängigkeiten.
  //  - edges (Anzeige): links = unterstützende Abhängigkeit, Mitte = Prozess,
  //    rechts = erzeugtes primäres Asset. Pfeile fließen sauber von links nach
  //    rechts, daher zeigen unterstützende Kanten VON der Abhängigkeit zum
  //    Nutzer/Prozess.
  const edges: GraphEdge[] = [];
  const adjacency = new Map<string, string[]>();
  const addAdj = (s: string, t: string) => {
    if (!adjacency.has(s)) adjacency.set(s, []);
    adjacency.get(s)!.push(t);
  };
  const isCritEdge = (s: string, t: string) =>
    (critOf.get(s) ?? 1) >= threshold && (critOf.get(t) ?? 1) >= threshold;

  for (const p of processes) {
    for (const pa of p.processAssets) {
      const proc = pid(p.id);
      const asset = aid(pa.assetId);
      // Analyse: Prozess ist auf alle zugeordneten Assets angewiesen (SPOF/Pfad)
      addAdj(proc, asset);
      if (pa.role === "PRIMARY") {
        // erzeugtes Asset rechts vom Prozess
        edges.push({
          id: `${proc}->${asset}`,
          source: proc,
          target: asset,
          label: "erzeugt",
          critical: isCritEdge(proc, asset),
        });
      } else {
        // unterstützendes Asset links vom Prozess (Kante zeigt zum Prozess)
        edges.push({
          id: `${asset}->${proc}`,
          source: asset,
          target: proc,
          label: "unterstützt",
          critical: isCritEdge(asset, proc),
        });
      }
    }
  }
  const assetIds = new Set(assets.map((a) => a.id));
  for (const r of relations) {
    if (!assetIds.has(r.assetId) || !assetIds.has(r.relatedAssetId)) continue;
    // Analyse: asset hängt von relatedAsset ab
    addAdj(aid(r.assetId), aid(r.relatedAssetId));
    // Anzeige: Abhängigkeit (relatedAsset) links, Nutzer (asset) rechts
    const s = aid(r.relatedAssetId);
    const t = aid(r.assetId);
    edges.push({
      id: `${s}->${t}`,
      source: s,
      target: t,
      label: "unterstützt",
      critical: isCritEdge(s, t),
    });
  }

  // Transitive Abhängigkeiten je kritischem Prozess → SPOF-Zählung je Asset
  const criticalProcesses = nodes.filter((n) => n.entity === "process" && n.critical);
  const dependents = new Map<string, Set<string>>(); // assetNodeId → Set kritischer Prozess-IDs
  for (const cp of criticalProcesses) {
    const seen = new Set<string>();
    const stack = [...(adjacency.get(cp.id) ?? [])];
    while (stack.length) {
      const cur = stack.pop()!;
      if (seen.has(cur)) continue;
      seen.add(cur);
      if (!dependents.has(cur)) dependents.set(cur, new Set());
      dependents.get(cur)!.add(cp.id);
      for (const next of adjacency.get(cur) ?? []) stack.push(next);
    }
  }

  const spofs: { id: string; name: string; count: number }[] = [];
  for (const n of nodes) {
    if (n.entity !== "asset") continue;
    const count = dependents.get(n.id)?.size ?? 0;
    n.dependentCriticalProcesses = count;
    if (count >= spofMin) {
      n.spof = true;
      spofs.push({ id: n.id, name: n.name, count });
    }
  }
  spofs.sort((a, b) => b.count - a.count);

  // Längster kritischer Pfad (Abhängigkeitskette): DFS über die Analyse-Adjazenz,
  // beschränkt auf kritische Knoten, ab kritischen Prozessen.
  const critAdj = new Map<string, string[]>();
  for (const [s, targets] of adjacency) {
    if ((critOf.get(s) ?? 1) < threshold) continue;
    const critTargets = targets.filter((t) => (critOf.get(t) ?? 1) >= threshold);
    if (critTargets.length) critAdj.set(s, critTargets);
  }
  const nameOf = new Map(nodes.map((n) => [n.id, n.name]));
  let longest: string[] = [];
  const dfs = (node: string, path: string[], visited: Set<string>) => {
    const next = critAdj.get(node) ?? [];
    if (next.length === 0) {
      if (path.length > longest.length) longest = [...path];
      return;
    }
    let extended = false;
    for (const nx of next) {
      if (visited.has(nx)) continue;
      extended = true;
      visited.add(nx);
      dfs(nx, [...path, nx], visited);
      visited.delete(nx);
    }
    if (!extended && path.length > longest.length) longest = [...path];
  };
  for (const cp of criticalProcesses) {
    dfs(cp.id, [cp.id], new Set([cp.id]));
  }

  return {
    nodes,
    edges,
    threshold,
    analysis: {
      spofs,
      criticalProcessCount: criticalProcesses.length,
      criticalEdgeCount: edges.filter((e) => e.critical).length,
      longestCriticalPath: longest.map((id) => nameOf.get(id) ?? id),
    },
  };
}