/*
 * CloudBeaver - Cloud Database Manager
 * Copyright (C) 2020-2022 DBeaver Corp and others
 *
 * Licensed under the Apache License, Version 2.0.
 * you may not use this file except in compliance with the License.
 */

import { action, computed, observable, runInAction } from 'mobx';
import { useCallback, useEffect, useMemo, useState } from 'react';

import { IFolderExplorerContext, useExecutor, useMapResource, useObjectRef, useObservableRef, useUserData } from '@cloudbeaver/core-blocks';
import { ConnectionInfoResource } from '@cloudbeaver/core-connections';
import { useService } from '@cloudbeaver/core-di';
import { NotificationService } from '@cloudbeaver/core-events';
import { ISyncExecutor, SyncExecutor } from '@cloudbeaver/core-executor';
import { type NavNode, NavNodeInfoResource, NavTreeResource } from '@cloudbeaver/core-navigation-tree';
import { ProjectInfoResource, ProjectsService } from '@cloudbeaver/core-projects';
import { CachedMapAllKey, ResourceKeyUtils } from '@cloudbeaver/core-sdk';
import { ILoadableState, MetadataMap, throttle } from '@cloudbeaver/core-utils';

import type { IElementsTreeAction } from './IElementsTreeAction';
import type { NavigationNodeRendererComponent } from './NavigationNodeComponent';

export type IElementsTreeCustomRenderer = (nodeId: string) => NavigationNodeRendererComponent | undefined;

export interface IElementsTreeNodeExpandedInfo {
  expanded: boolean;
  expandable?: boolean;
}

export type IElementsTreeNodeExpandInfoGetter = (
  nodeId: string,
  state: ITreeNodeState
) => IElementsTreeNodeExpandedInfo | null;

export type IElementsTreeFilter = (
  filter: string,
  node: NavNode,
  children: string[],
  state: MetadataMap<string, ITreeNodeState>
) => string[];

export interface ITreeNodeState {
  selected: boolean;
  expanded: boolean;
  showInFilter: boolean;
}

interface IElementsTreeUserState {
  nodeState: Array<[string, ITreeNodeState]>;
  filter: string;
}

export interface IElementsTreeSettings {
  filter: boolean;
  filterAll: boolean;
  saveExpanded: boolean;
  foldersTree: boolean;
  saveFilter: boolean;
  showFolderExplorerPath: boolean;
  configurable: boolean;
  projects: boolean;
}

export interface IElementsTreeOptions {
  settings?: IElementsTreeSettings;
  disabled?: boolean;
  filters?: IElementsTreeFilter[];
  renderers?: IElementsTreeCustomRenderer[];
  expandStateGetters?: IElementsTreeNodeExpandInfoGetter[];
  localState?: MetadataMap<string, ITreeNodeState>;
  getChildren: (id: string) => string[] | undefined;
  loadChildren: (id: string, manual: boolean) => Promise<boolean>;
  onFilter?: (value: string) => Promise<void> | void;
  onSelect?: (node: NavNode, state: boolean) => Promise<void> | void;
  onExpand?: (node: NavNode, state: boolean) => Promise<void> | void;
  isGroup?: (node: NavNode) => boolean;
  customSelect?: (node: NavNode, multiple: boolean, nested: boolean) => Promise<void> | void;
  beforeSelect?: (node: NavNode, multiple: boolean, nested: boolean) => Promise<void> | void;
  customSelectReset?: ()=> Promise<void> | void;
}

interface IOptions extends IElementsTreeOptions {
  baseRoot: string;
  root: string;
  folderExplorer: IFolderExplorerContext;
}

export interface IElementsTree extends ILoadableState {
  actions: ISyncExecutor<IElementsTreeAction>;
  settings?: IElementsTreeSettings;
  baseRoot: string;
  root: string;
  readonly filtering: boolean;
  readonly filter: string;
  loading: boolean;
  disabled: boolean;
  renderers: IElementsTreeCustomRenderer[];
  state: MetadataMap<string, ITreeNodeState>;
  userData: IElementsTreeUserState;

  getNodeState: (nodeId: string) => ITreeNodeState;
  isNodeExpanded: (nodeId: string, ignoreFilter?: boolean) => boolean;
  isNodeExpandable: (nodeId: string) => boolean;
  getExpanded: () => string[];
  getSelected: () => string[];
  isNodeSelected: (nodeId: string) => boolean;
  isNodeIndeterminateSelected: (nodeId: string) => boolean;
  getNodeChildren: (nodeId: string) => string[];
  isGroup?: (node: NavNode) => boolean;
  setFilter: (value: string) => Promise<void>;
  select: (node: NavNode, multiple: boolean, nested: boolean) => Promise<void>;
  resetSelection(): Promise<void>;
  expand: (node: NavNode, state: boolean) => Promise<void>;
  show: (nodeId: string, parents: string[]) => Promise<void>;
  refresh: (nodeId: string) => Promise<void>;
  collapse: () => void;
}

export function useElementsTree(options: IOptions): IElementsTree {
  const projectsService = useService(ProjectsService);
  const notificationService = useService(NotificationService);
  const navNodeInfoResource = useService(NavNodeInfoResource);
  const navTreeResource = useService(NavTreeResource);
  const connectionInfoResource = useService(ConnectionInfoResource);

  const [localTreeNodesState] = useState(() => new MetadataMap<string, ITreeNodeState>(() => ({
    selected: false,
    expanded: false,
    showInFilter: false,
  })));

  options = useObjectRef(options);
  const state = options.localState || localTreeNodesState;

  const functionsRef = useObjectRef({
    async loadTree(nodeId: string) {
      await connectionInfoResource.load(CachedMapAllKey);
      const preloaded = await navTreeResource.preloadNodeParents(options.folderExplorer.state.fullPath);

      if (!preloaded) {
        return;
      }

      let children = [nodeId];

      while (children.length > 0) {
        const nextChildren: string[] = [];

        for (const child of children) {
          await navTreeResource.waitLoad();
          await navNodeInfoResource.waitLoad();

          const expanded = elementsTree.isNodeExpanded(child, true);
          if (!expanded && child !== options.root) {
            if (navNodeInfoResource.isOutdated(child)) {
              const node = navNodeInfoResource.get(child);

              if (node?.parentId !== undefined && !navTreeResource.isOutdated(node.parentId)) {
                await navNodeInfoResource.load(child);
              }
            }
            continue;
          }

          const loaded = await options.loadChildren(child, false);

          if (!loaded) {
            const node = navNodeInfoResource.get(child);

            if (node) {
              await elementsTree.expand(node, false);
            }
            continue;
          }

          nextChildren.push(...(navTreeResource.get(child) || []));
        }

        children = nextChildren;
      }
    },

    getNestedChildren(nodeId: string): string[] {
      const nestedChildren: string[] = [];
      const prevChildren = elementsTree.getNodeChildren(nodeId);
      nestedChildren.push(...prevChildren);

      while (prevChildren.length) {
        const nodeKey = prevChildren.shift()!;
        const children = elementsTree.getNodeChildren(nodeKey);
        prevChildren.push(...children);
        nestedChildren.push(...children);
      }

      return nestedChildren;
    },

    async resetSelection() {
      for (const [id, nodeState] of state) {
        if (nodeState.selected) {
          nodeState.selected = false;

          if (options.onSelect) {
            const node = navNodeInfoResource.get(id);

            if (node) {
              await options.onSelect(node, false);
            }
          }
        }
      }
    },

    async clearSelection(nodeId: string) {
      const node = navNodeInfoResource.get(nodeId);

      const ignore = node && options.isGroup?.(node)
        ? this.getNestedChildren(nodeId)
        : [];

      for (const [id, nodeState] of state) {
        if (nodeState.selected && id !== nodeId && !ignore.includes(id)) {
          nodeState.selected = false;

          if (options.onSelect) {
            const node = navNodeInfoResource.get(id);

            if (node) {
              await options.onSelect(node, false);
            }
          }
        }
      }
    },
    async setSelection(nodeId: string, selected: boolean): Promise<void> {
      const node = navNodeInfoResource.get(nodeId);

      if (!node) {
        return;
      }

      const treeNodeState = state.get(nodeId);
      const selectionState = elementsTree.isNodeSelected(nodeId);

      if (selectionState === selected) {
        return;
      }

      if (options.isGroup?.(node)) {
        const children = elementsTree.getNodeChildren(nodeId);

        for (const child of children) {
          await this.setSelection(child, selected);
        }

        if (children.length === 0) {
          return;
        }
      } else {
        treeNodeState.selected = selected;
      }

      await options.onSelect?.(node, selected);
    },
  });

  const userData = useUserData<IElementsTreeUserState>(
    `elements-tree-${options.baseRoot}`,
    () => observable<IElementsTreeUserState>({
      nodeState: [],
      filter: '',
    }),
    async data => {
      if (!options.settings?.saveFilter) {
        data.filter = '';
      }

      if (!options.settings?.saveExpanded) {
        data.nodeState = [];
      }

      state.sync(data.nodeState);

      elementsTree.loading = true;
      try {
        await functionsRef.loadTree(options.root);
      } finally {
        elementsTree.loading = false;
      }
    },
    data => (
      typeof data === 'object'
      && typeof data.filter === 'string'
      && Array.isArray(data.nodeState)
    )
  );

  const renderers = useMemo(() => options.renderers || [], [options.renderers]);

  const elementsTree = useObservableRef<IElementsTree>(() => ({
    actions: new SyncExecutor(),
    state,
    loading: options.settings?.saveExpanded || false,
    get filter(): string {
      return this.userData.filter;
    },
    get filtering() {
      return this.filter !== '';
    },
    isLoading() {
      return this.loading;
    },
    isLoaded() {
      return true;
    },
    getNodeState(nodeId: string) {
      return this.state.get(nodeId);
    },
    isNodeExpanded(nodeId: string, ignoreFilter?: boolean): boolean {
      if (nodeId === this.root) {
        return true;
      }

      if (this.filtering && this.settings?.filterAll && !ignoreFilter) {
        return this.getNodeChildren(nodeId).length > 0;
      }

      const nodeState = this.getNodeState(nodeId);
      const expanded = nodeState.expanded || nodeState.showInFilter;

      if (!expanded && options.expandStateGetters?.length) {
        return options
          .expandStateGetters
          .map(getExpandState => getExpandState(nodeId, nodeState))
          .filter(stateInfo => stateInfo !== null)
          .some(stateInfo => stateInfo?.expanded);
      }

      return expanded;
    },
    isNodeExpandable(nodeId: string): boolean {
      if (nodeId === this.root) {
        return true;
      }

      if (options.expandStateGetters?.length) {
        const nodeState = this.getNodeState(nodeId);

        return options
          .expandStateGetters
          .map(getExpandState => getExpandState(nodeId, nodeState))
          .filter(stateInfo => stateInfo !== null)
          .every(stateInfo => stateInfo?.expandable !== false);
      }

      return true;
    },
    getExpanded(): string[] {
      return Array.from(this.state).filter(([key, state]) => state.expanded).map(([key]) => key);
    },
    getSelected(): string[] {
      return Array.from(this.state).filter(([key, state]) => state.selected).map(([key]) => key);
    },
    isNodeSelected(nodeId: string): boolean {
      const node = navNodeInfoResource.get(nodeId);

      if (node && elementsTree.isGroup?.(node)) {
        const children = this.getNodeChildren(nodeId);

        if (children.length > 0) {
          return children.every(child => this.isNodeSelected(child));
        }

        return false;
      }

      return this.getNodeState(nodeId).selected;
    },
    isNodeIndeterminateSelected(nodeId: string): boolean {
      if (this.isNodeSelected(nodeId)) {
        return false;
      }

      const node = navNodeInfoResource.get(nodeId);

      if (node && elementsTree.isGroup?.(node)) {
        const children = options.getChildren(nodeId) || [];

        if (children.length > 0) {
          return children.some(child => this.isNodeSelected(child) || this.isNodeIndeterminateSelected(child));
        }

        return false;
      }

      return false;
    },
    getNodeChildren(nodeId: string): string[] {
      const node = navNodeInfoResource.get(nodeId);

      if (!node) {
        return []; // Maybe filter should accept nodeId, so we be able to apply filters to empty node
      }

      return (options.filters || [])
        .reduce(
          (children, filter) => filter(elementsTree.filter, node, children, this.state),
          options.getChildren(node.id) || []
        );
    },
    async setFilter(value: string) {
      runInAction(() => {
        this.userData.filter = value;

        for (const nodeState of this.state.values()) {
          nodeState.showInFilter = false;
        }
      });

      await options.onFilter?.(value);
    },
    collapse() {
      for (const state of this.state.values()) {
        state.expanded = false;
        state.showInFilter = false;
      }
    },
    async refresh(nodeId: string): Promise<void> {
      try {
        await navTreeResource.refreshTree(nodeId);
      } catch (exception: any) {
        notificationService.logException(exception, 'app_navigationTree_refresh_error');
      }
    },
    async show(nodeId: string, path: string[]): Promise<void> {
      const preloaded = await navTreeResource.preloadNodeParents(path, nodeId);

      if (!preloaded) {
        notificationService.logError({
          title: 'app_navigationTree_node_not_found',
          message: nodeId,
        });
      }

      if (preloaded) {
        runInAction(() => {
          for (const parent of path) {
            const state = this.getNodeState(parent);
            state.expanded = true;
          }

          const node = navNodeInfoResource.get(nodeId)!;

          this.select(node, false, false);
          this.actions.execute({ type: 'show', nodeId });
        });

        if (path.length > 0) {
          await functionsRef.loadTree(path[0]);
        }
      }
    },
    async expand(node: NavNode, state: boolean) {
      if (!this.isNodeExpandable(node.id)) {
        return;
      }

      const treeNodeState = this.state.get(node.id);

      try {
        if (state || (this.filtering && !treeNodeState.showInFilter)) {
          state = await options.loadChildren(node.id, true);
        }

        if (this.filtering) {
          treeNodeState.showInFilter = !treeNodeState.showInFilter && state;

          if (!treeNodeState.showInFilter) {
            const nested = functionsRef.getNestedChildren(node.id);

            for (const nodeId of nested) {
              const treeNodeState = this.state.get(nodeId);
              treeNodeState.showInFilter = false;
            }
          }
        } else {
          await options.onExpand?.(node, state);
          treeNodeState.expanded = state;
        }

        if (state) {
          await functionsRef.loadTree(node.id);
        }
      } catch {
        treeNodeState.expanded = false;

        if (this.filtering) {
          treeNodeState.showInFilter = false;
        }
      }
    },
    async select(node: NavNode, multiple: boolean, nested: boolean) {
      if (options.customSelect) {
        await options.customSelect(node, multiple, nested);
        return;
      }

      if (options.beforeSelect) {
        await options.beforeSelect(node, multiple, nested);
      }

      const selected = this.isNodeSelected(node.id);

      if (!multiple) {
        await functionsRef.clearSelection(node.id);

        if (selected) {
          return;
        }
      }

      await functionsRef.setSelection(node.id, !selected);
    },
    async resetSelection(): Promise<void> {
      if (options.customSelectReset) {
        await options.customSelectReset();
        return;
      }
      await functionsRef.resetSelection();
    },
  }), {
    settings: observable.ref,
    isGroup: observable.ref,
    disabled: observable.ref,
    root: observable.ref,
    filter: computed,
    filtering: computed,
    loading: observable.ref,
    renderers: observable.ref,
    baseRoot: observable.ref,
    collapse: action.bound,
    userData: observable.ref,
  }, {
    isGroup: options.isGroup,
    disabled: options.disabled,
    root: options.root,
    settings: options.settings,
    baseRoot: options.baseRoot,
    renderers,
    userData,
  }, ['isLoading', 'isLoaded']);

  function exitNodeFolder(nodeId: string) {
    runInAction(() => {
      const folderExplorer = options.folderExplorer;

      if (folderExplorer.state.fullPath.length === 1 || nodeId === options.baseRoot) {
        return;
      }

      const pathIndex = folderExplorer.state.fullPath.indexOf(nodeId);

      if (pathIndex >= 0) {
        folderExplorer.state.fullPath = folderExplorer.state.fullPath.slice(0, pathIndex);
        folderExplorer.state.folder = folderExplorer.state.fullPath[pathIndex - 1];
        folderExplorer.state.path = folderExplorer.state.fullPath.slice(0, pathIndex - 1);
      }
    });
  }

  useEffect(() => {
    functionsRef.loadTree(options.root);
  }, [options.root]);

  const loadTreeThreshold = useCallback(throttle(function refreshRoot() {
    functionsRef.loadTree(options.root);
  }, 100), []);

  useMapResource(useElementsTree, ProjectInfoResource, CachedMapAllKey, {
    onData: () => {
      loadTreeThreshold();
    },
  });

  useExecutor({
    executor: navNodeInfoResource.onDataOutdated,
    postHandlers: [loadTreeThreshold],
  });

  useExecutor({
    executor: projectsService.onActiveProjectChange,
    handlers: [loadTreeThreshold],
  });

  useExecutor({
    executor: navTreeResource.onItemAdd,
    handlers: [function exitFolder(key) {
      ResourceKeyUtils.forEach(key, key => {
        const children = navTreeResource.get(key);

        if (!children || children.length === 0) {
          exitNodeFolder(key);
        }
      });
    }],
  });

  useExecutor({
    executor: navNodeInfoResource.onItemDelete,
    handlers: [function deleteNodeState(key) {
      runInAction(() => {
        ResourceKeyUtils.forEach(key, key => {
          state.delete(key);
        });
      });
    }],
  });

  useExecutor({
    executor: navTreeResource.onItemDelete,
    handlers: [async function collapseDeletedTree(key) {
      await ResourceKeyUtils.forEachAsync(key, async key => {
        const node = navNodeInfoResource.get(key);

        if (node) {
          await elementsTree.expand(node, false);

          exitNodeFolder(key);
        }
      });
    }],
  });

  return elementsTree;
}