import type { Edge, Node } from '@xyflow/svelte';

export const JOIN_MODE_ANY = 'any';
export const JOIN_MODE_ALL = 'all';

export type JoinMode = typeof JOIN_MODE_ANY | typeof JOIN_MODE_ALL;

export type JoinModeAnalysis = {
  incomingCount: number;
  mode: JoinMode | null;
  invalidMode: boolean;
  allAllowed: boolean;
  allDisabledReason: string;
};

const text = (value: unknown) => (value == null ? '' : String(value).trim());

export function parseJoinMode(value: unknown): JoinMode | null {
  if (value === undefined) {
    return JOIN_MODE_ANY;
  }
  const normalized = text(value).toLowerCase();
  if (normalized === JOIN_MODE_ANY) {
    return JOIN_MODE_ANY;
  }
  if (normalized === JOIN_MODE_ALL) {
    return JOIN_MODE_ALL;
  }
  return null;
}

export function getJoinModeBadge(value: unknown) {
  return parseJoinMode(value) === JOIN_MODE_ALL ? '等待全部' : '';
}

export function analyzeJoinMode(
  nodes: Node[],
  edges: Edge[],
  nodeId: string,
): JoinModeAnalysis {
  const targetNode = nodes.find((node) => node.id === nodeId);
  const directInward = edges.filter((edge) => edge.target === nodeId);
  const hasJoinMode = targetNode?.data
    ? Object.prototype.hasOwnProperty.call(targetNode.data, 'joinMode')
    : false;
  const mode = parseJoinMode(targetNode?.data?.joinMode);
  const invalidMode = hasJoinMode && mode === null;

  if (!targetNode) {
    return {
      incomingCount: directInward.length,
      mode,
      invalidMode,
      allAllowed: false,
      allDisabledReason: '节点不存在，请刷新画布后重试。',
    };
  }

  if (text(targetNode.parentId)) {
    return {
      incomingCount: directInward.length,
      mode,
      invalidMode,
      allAllowed: false,
      allDisabledReason: '显式循环子图暂不支持等待全部上游，请使用“任一上游完成”。',
    };
  }

  if (directInward.length <= 1) {
    return {
      incomingCount: directInward.length,
      mode,
      invalidMode,
      allAllowed: true,
      allDisabledReason: '',
    };
  }

  const guaranteedNodes = findGuaranteedNodes(nodes, edges);
  const allAllowed = directInward.every(
    (edge) => !hasEdgeCondition(edge) && guaranteedNodes.has(edge.source),
  );
  if (allAllowed) {
    return {
      incomingCount: directInward.length,
      mode,
      invalidMode,
      allAllowed: true,
      allDisabledReason: '',
    };
  }

  let reason = '存在条件、互斥或无法证明必达的上游路径，可能永久等待。请调整连线或使用“任一上游完成”。';
  if (directInward.some(hasEdgeCondition)) {
    reason = '存在带条件的直接入边，部分入边可能不会到达。请调整连线或使用“任一上游完成”。';
  } else if (directInward.some((edge) => {
    const source = nodes.find((node) => node.id === edge.source);
    return hasAdvancedCondition(source);
  })) {
    reason = '上游节点包含高级执行条件，无法保证每条入边都会到达。请调整条件或使用“任一上游完成”。';
  }

  return {
    incomingCount: directInward.length,
    mode,
    invalidMode,
    allAllowed: false,
    allDisabledReason: reason,
  };
}

function findGuaranteedNodes(nodes: Node[], edges: Edge[]) {
  const guaranteed = new Set(
    nodes
      .filter((node) => !text(node.parentId) && node.type === 'startNode')
      .map((node) => node.id),
  );
  const inwardByTarget = new Map<string, Edge[]>();
  edges.forEach((edge) => {
    const inward = inwardByTarget.get(edge.target) || [];
    inward.push(edge);
    inwardByTarget.set(edge.target, inward);
  });

  let changed = true;
  while (changed) {
    changed = false;
    nodes.forEach((node) => {
      if (
        text(node.parentId)
        || guaranteed.has(node.id)
        || hasAdvancedCondition(node)
      ) {
        return;
      }
      const mode = parseJoinMode(node.data?.joinMode);
      if (!mode) {
        return;
      }
      const inward = inwardByTarget.get(node.id) || [];
      const isGuaranteed = mode === JOIN_MODE_ALL
        ? inward.length > 0 && inward.every(
          (edge) => !hasEdgeCondition(edge) && guaranteed.has(edge.source),
        )
        : inward.some(
          (edge) => !hasEdgeCondition(edge) && guaranteed.has(edge.source),
        );
      if (isGuaranteed) {
        guaranteed.add(node.id);
        changed = true;
      }
    });
  }
  return guaranteed;
}

function hasAdvancedCondition(node: Node | undefined) {
  return Boolean(text(node?.data?.condition));
}

function hasEdgeCondition(edge: Edge) {
  return Boolean(text(edge.data?.condition));
}