import { Op } from 'sequelize';
import { Context, utils } from '@nocobase/actions';
import { MultipleRelationRepository } from '@nocobase/database';
import WorkflowModel from '../models/Workflow';

export async function create(context: Context, next) {
  const { db } = context;
  const repository = utils.getRepositoryFromParams(context) as MultipleRelationRepository;
  const { whitelist, blacklist, updateAssociationValues, values, associatedIndex: workflowId } = context.action.params;

  context.body = await db.sequelize.transaction(async transaction => {
    const workflow = await repository.getSourceModel(transaction) as WorkflowModel;
    if (workflow.executed) {
      context.throw(400, 'Node could not be created in executed workflow');
    }

    const instance = await repository.create({
      values,
      whitelist,
      blacklist,
      updateAssociationValues,
      context,
      transaction
    });

    if (!instance.upstreamId) {
      const previousHead = await repository.findOne({
        filter: {
          id: {
            $ne: instance.id
          },
          upstreamId: null
        },
        transaction
      });
      if (previousHead) {
        await previousHead.setUpstream(instance, { transaction });
        await instance.setDownstream(previousHead, { transaction });
        instance.set('downstream', previousHead);
      }
      return instance;
    }

    const upstream = await instance.getUpstream({ transaction });

    if (instance.branchIndex == null) {
      const downstream = await upstream.getDownstream({ transaction });

      if (downstream) {
        await downstream.setUpstream(instance, { transaction });
        await instance.setDownstream(downstream, { transaction });
        instance.set('downstream', downstream);
      }

      await upstream.update({
        downstreamId: instance.id
      }, { transaction });

      upstream.set('downstream', instance);
    } else {
      const [downstream] = await upstream.getBranches({
        where: {
          id: {
            [Op.ne]: instance.id
          },
          branchIndex: instance.branchIndex
        },
        transaction
      });

      if (downstream) {
        await downstream.update({
          upstreamId: instance.id,
          branchIndex: null
        }, { transaction });
        await instance.setDownstream(downstream, { transaction });
        instance.set('downstream', downstream);
      }
    }

    instance.set('upstream', upstream);
  });

  await next();
}

function searchBranchNodes(nodes, from): any[] {
  const branchHeads = nodes
    .filter((item: any) => item.upstreamId === from.id && item.branchIndex != null);
  return branchHeads.reduce((flatten: any[], head) => flatten.concat(searchBranchDownstreams(nodes, head)), []) as any[];
}

function searchBranchDownstreams(nodes, from) {
  let result = [];
  for (let search = from; search; search = search.downstream) {
    result = [...result, search, ...searchBranchNodes(nodes, search)];
  }
  return result;
}

export async function destroy(context: Context, next) {
  const { db } = context;
  const repository = utils.getRepositoryFromParams(context) as MultipleRelationRepository;
  const { filterByTk } = context.action.params;

  context.body = await db.sequelize.transaction(async transaction => {
    const workflow = await repository.getSourceModel(transaction) as WorkflowModel;
    if (workflow.executed) {
      context.throw(400, 'Nodes in executed workflow could not be deleted');
    }

    const fields = ['id', 'upstreamId', 'downstreamId', 'branchIndex'];
    const instance = await repository.findOne({
      filterByTk,
      fields: [...fields, 'workflowId'],
      appends: ['upstream', 'downstream'],
      transaction
    });
    const { upstream, downstream } = instance.get();

    if (upstream && upstream.downstreamId === instance.id) {
      await upstream.update({
        downstreamId: instance.downstreamId
      }, { transaction });
    }

    if (downstream) {
      await downstream.update({
        upstreamId: instance.upstreamId,
        branchIndex: instance.branchIndex
      }, { transaction });
    }

    const nodes = await repository.find({
      filter: {
        workflowId: instance.workflowId
      },
      fields,
      transaction
    });
    const nodesMap = new Map();
    // make map
    nodes.forEach(item => {
      nodesMap.set(item.id, item);
    });
    // overwrite
    nodesMap.set(instance.id, instance);
    // make linked list
    nodes.forEach(item => {
      if (item.upstreamId) {
        item.upstream = nodesMap.get(item.upstreamId);
      }
      if (item.downstreamId) {
        item.downstream = nodesMap.get(item.downstreamId);
      }
    });

    const branchNodes = searchBranchNodes(nodes, instance);

    await repository.destroy({
      filterByTk: [instance.id, ...branchNodes.map(item => item.id)],
      transaction
    });

    return instance;
  });

  await next();
}

export async function update(context: Context, next) {
  const { db } = context;
  const repository = utils.getRepositoryFromParams(context);
  const { filterByTk, values, whitelist, blacklist, filter, updateAssociationValues } = context.action.params;
  context.body = await db.sequelize.transaction(async transaction => {
    // TODO(optimize): duplicated instance query
    const { workflow } = await repository.findOne({
      filterByTk,
      appends: ['workflow.executed'],
      transaction
    });
    if (workflow.executed) {
      context.throw(400, 'Nodes in executed workflow could not be reconfigured');
    }

    return repository.update({
      filterByTk,
      values,
      whitelist,
      blacklist,
      filter,
      updateAssociationValues,
      context,
      transaction
    });
  });

  await next();
}