/**
 * Single canonical start node on the canvas — id and type follow workflow primary entry kind.
 */

import type { CanvasConnection, CanvasNode } from '../../editor/FlowCanvas';
import type { NodeType } from '../../../../api/workflowApi';
import type { WorkflowEntryPoint } from '../../../../api/workflowApi';
import { getLabel } from '../shared/utils';

export const CANVAS_START_NODE_ID = 'start';

/** Primary entry is always the first invocation (gear configures index 0). */
export function getPrimaryEntry(invocations: WorkflowEntryPoint[] | undefined): WorkflowEntryPoint | undefined {
  return invocations?.[0];
}

/** Kind of the primary entry (drives canvas node type) */
export function getPrimaryStartKind(invocations: WorkflowEntryPoint[] | undefined): string {
  return getPrimaryEntry(invocations)?.kind ?? 'manual';
}

function entryTitle(entry: WorkflowEntryPoint | undefined, language: string): string {
  if (!entry?.title) return '';
  const t = entry.title;
  if (typeof t === 'string') return t.trim();
  const s = t[language] || t.de || t.en || Object.values(t)[0];
  return (s != null ? String(s) : '').trim();
}

export function mapKindToNodeType(kind: string): string {
  if (kind === 'form') return 'trigger.form';
  if (kind === 'schedule') return 'trigger.schedule';
  // Immer aktiv: zunächst Standard-Start; Listener (E-Mail, Webhook, …) folgt separat
  if (kind === 'always_on') return 'trigger.manual';
  return 'trigger.manual';
}

function categoryForKind(kind: string): 'on_demand' | 'always_on' {
  if (kind === 'manual' || kind === 'form') return 'on_demand';
  return 'always_on';
}

function titleForStartNode(
  kind: string,
  invocations: WorkflowEntryPoint[],
  nodeTypes: NodeType[],
  language: string
): string {
  const custom = entryTitle(getPrimaryEntry(invocations), language);
  if (custom) return custom;
  const nt = nodeTypes.find((n) => n.id === mapKindToNodeType(kind));
  if (nt) return getLabel(nt.label, language);
  return 'Start';
}

/** Rewire connections when replacing node ids */
function rewireConnections(
  connections: CanvasConnection[],
  fromId: string,
  toId: string
): CanvasConnection[] {
  if (fromId === toId) return connections;
  return connections.map((c) => ({
    ...c,
    sourceId: c.sourceId === fromId ? toId : c.sourceId,
    targetId: c.targetId === fromId ? toId : c.targetId,
  }));
}

/** Deep-rewrite ref.nodeId in parameters (e.g. flow.ifElse condition.ref) */
function rewireRefInParams(params: unknown, fromIds: Set<string>, toId: string): unknown {
  if (params == null) return params;
  if (typeof params === 'object' && params !== null && 'type' in params && 'nodeId' in params) {
    const obj = params as { type?: string; nodeId?: string; path?: unknown };
    if (obj.type === 'ref' && typeof obj.nodeId === 'string' && fromIds.has(obj.nodeId)) {
      return { ...obj, nodeId: toId };
    }
  }
  if (Array.isArray(params)) {
    return params.map((item) => rewireRefInParams(item, fromIds, toId));
  }
  if (typeof params === 'object' && params !== null) {
    const out: Record<string, unknown> = {};
    for (const [k, v] of Object.entries(params)) {
      out[k] = rewireRefInParams(v, fromIds, toId);
    }
    return out;
  }
  return params;
}

/** Rewrite refs in all nodes' parameters when trigger id changes */
function rewireRefsInNodes(
  nodes: CanvasNode[],
  fromIds: Set<string>,
  toId: string
): CanvasNode[] {
  if (fromIds.size === 0) return nodes;
  return nodes.map((n) => {
    const p = n.parameters;
    if (!p || typeof p !== 'object') return n;
    const next = rewireRefInParams(p, fromIds, toId);
    if (next === p) return n;
    return { ...n, parameters: next as Record<string, unknown> };
  });
}

/** Remove duplicate trigger nodes; keep first, merge connections onto it */
function dedupeTriggers(
  nodes: CanvasNode[],
  connections: CanvasConnection[]
): { nodes: CanvasNode[]; connections: CanvasConnection[] } {
  const triggers = nodes.filter((n) => n.type.startsWith('trigger.'));
  if (triggers.length <= 1) return { nodes, connections };

  const keep = triggers[0];
  const removeIds = new Set(triggers.slice(1).map((n) => n.id));
  let nextConn = connections;
  for (const rid of removeIds) {
    nextConn = rewireConnections(nextConn, rid, keep.id);
  }
  const newNodes = nodes.filter((n) => !removeIds.has(n.id));
  return { nodes: newNodes, connections: nextConn };
}

/** Normalize canonical id `start` and update type/labels from primary kind */
export function syncCanvasStartNode(
  nodes: CanvasNode[],
  connections: CanvasConnection[],
  invocations: WorkflowEntryPoint[],
  nodeTypes: NodeType[],
  language: string
): { nodes: CanvasNode[]; connections: CanvasConnection[] } {
  const kind = getPrimaryStartKind(invocations);
  const targetType = mapKindToNodeType(kind);
  const title = titleForStartNode(kind, invocations, nodeTypes, language);
  const nt = nodeTypes.find((n) => n.id === targetType);
  const inputs = nt?.inputs ?? 0;
  const outputs = nt?.outputs ?? 1;

  const triggerIdsBeforeDedupe = new Set(nodes.filter((n) => n.type.startsWith('trigger.')).map((n) => n.id));
  let { nodes: ns, connections: cs } = dedupeTriggers(nodes, connections);

  let startIdx = ns.findIndex((n) => n.type.startsWith('trigger.'));
  if (startIdx === -1) {
    const newNode: CanvasNode = {
      id: CANVAS_START_NODE_ID,
      type: targetType,
      x: 100,
      y: 120,
      title,
      label: title,
      inputs,
      outputs,
      color: nt?.meta?.color as string | undefined,
      parameters: {},
    };
    ns = rewireRefsInNodes([newNode, ...ns], triggerIdsBeforeDedupe, CANVAS_START_NODE_ID);
    return { nodes: ns, connections: cs };
  }

  const current = ns[startIdx];
  const oldId = current.id;
  let nextConn = cs;
  if (oldId !== CANVAS_START_NODE_ID) {
    nextConn = rewireConnections(nextConn, oldId, CANVAS_START_NODE_ID);
  }
  ns = rewireRefsInNodes(ns, triggerIdsBeforeDedupe, CANVAS_START_NODE_ID);

  const updated: CanvasNode = {
    ...current,
    id: CANVAS_START_NODE_ID,
    type: targetType,
    title,
    label: title,
    inputs,
    outputs,
    color: nt?.meta?.color as string | undefined,
    parameters:
      targetType === current.type ? current.parameters ?? {} : preserveParametersForTypeSwitch(current, targetType),
  };

  const nextNodes = [...ns];
  nextNodes[startIdx] = updated;
  return { nodes: nextNodes, connections: nextConn };
}

function preserveParametersForTypeSwitch(node: CanvasNode, newType: string): Record<string, unknown> {
  const p = node.parameters ?? {};
  if (newType === 'trigger.form' && p.formFields) return { formFields: p.formFields };
  if (newType === 'trigger.schedule' && (p.cron || p.schedule)) {
    const out: Record<string, unknown> = {};
    if (p.cron != null) out.cron = p.cron;
    if (p.schedule != null) out.schedule = p.schedule;
    return out;
  }
  return {};
}

/** Build invocations: replace primary (index 0), keep further entries (e.g. listener config later). */
export function buildInvocationsForPrimaryKind(
  kind: string,
  existing: WorkflowEntryPoint[] | undefined,
  titleDe: string
): WorkflowEntryPoint[] {
  const list = existing ?? [];
  const primaryId =
    list[0]?.id ??
    (typeof crypto !== 'undefined' && crypto.randomUUID ? crypto.randomUUID() : `ep-${Date.now()}`);
  const category = categoryForKind(kind);
  const primary: WorkflowEntryPoint = {
    id: primaryId,
    kind,
    category,
    enabled: true,
    title: { de: titleDe, en: titleDe, fr: titleDe },
    description: {},
    config: {},
  };
  const rest = list.slice(1).filter((x) => x.id !== primaryId);
  return [primary, ...rest];
}