import * as modelUtil from 'app/client/models/modelUtil';
// This is circular import, but only for types so it's fine.
import type {DocModel, ViewFieldRec} from 'app/client/models/DocModel';
import {Style} from 'app/client/models/Styles';
import * as UserType from 'app/client/widgets/UserType';
import {ifNotSet} from 'app/common/gutil';
import * as ko from 'knockout';
import intersection from "lodash/intersection";
import isEqual from "lodash/isEqual";

export class ViewFieldConfig {
  /** If there are multiple columns selected in the viewSection */
  public multiselect: ko.Computed<boolean>;
  /** If all selected columns have the same widget list. */
  public sameWidgets: ko.Computed<boolean>;
  /** Widget options for a field or multiple fields */
  public options: CommonOptions;

  // Rest of the options mimic the same options from ViewFieldRec.
  public wrap: modelUtil.KoSaveableObservable<boolean|undefined>;
  public widget: ko.Computed<string|undefined>;
  public alignment: modelUtil.KoSaveableObservable<string|undefined>;
  public textColor: modelUtil.KoSaveableObservable<string|undefined>;
  public fillColor: modelUtil.KoSaveableObservable<string|undefined>;
  public fontBold: modelUtil.KoSaveableObservable<boolean|undefined>;
  public fontUnderline: modelUtil.KoSaveableObservable<boolean|undefined>;
  public fontItalic: modelUtil.KoSaveableObservable<boolean|undefined>;
  public fontStrikethrough: modelUtil.KoSaveableObservable<boolean|undefined>;
  private _fields: ko.PureComputed<ViewFieldRec[]>;
  constructor(private _field: ViewFieldRec, private _docModel: DocModel) {
    // Everything here will belong to a _field, this class is just a builder.
    const owner = _field;

    // Get all selected fields from the viewSection, if there is only one field
    // selected (or the selection is empty) return it in an array.
    this._fields = owner.autoDispose(ko.pureComputed(() => {
      const list = this._field.viewSection().selectedFields();
      if (!list || !list.length) {
        return [_field];
      }
      // Make extra sure that field and column is not disposed, most of the knockout
      // based entities, don't dispose their computed observables. As we keep references
      // for them, it can happen that some of them are disposed while we are still
      // computing something (mainly when columns are removed or restored using undo).
      return list.filter(f => !f.isDisposed() && !f.column().isDisposed());
    }));

    // Just a helper field to see if we have multiple selected columns or not.
    this.multiselect = owner.autoDispose(ko.pureComputed(() => this._fields().length > 1));

    // Calculate if all columns share the same allowed widget list (like for Numeric type
    // we have normal TextBox and Spinner). This will be used to allow the user to change
    // this type if such columns are selected.
    this.sameWidgets = owner.autoDispose(ko.pureComputed(() => {
      const list = this._fields();
      // If we have only one field selected, list is always the same.
      if (list.length <= 1) { return true; }
      // Now get all widget list and calculate intersection of the Sets.
      // Widget types are just strings defined in UserType.
      const widgets = list.map(c =>
        Object.keys(UserType.typeDefs[c.column().pureType()]?.widgets ?? {})
      );
      return intersection(...widgets).length === widgets[0]?.length;
    }));

    // Changing widget type is not trivial, as we need to carefully reset all
    // widget options to their default values, and there is a nuance there.
    this.widget = owner.autoDispose(ko.pureComputed({
      read: () => {
        // For single column, just return its widget type.
        if (!this.multiselect()) {
          return this._field.widget();
        }
        // If all have the same value, return it, otherwise
        // return a default value for this option "undefined"
        const values = this._fields().map(f => f.widget());
        if (allSame(values)) {
          return values[0];
        } else {
          return undefined;
        }
      },
      write: (widget) => {
        // Go through all the fields, and reset them all.
        for(const field of this._fields.peek()) {
          // Reset the entire JSON, so that all options revert to their defaults.
          const previous = field.widgetOptionsJson.peek();
          // We don't need to bundle anything (actions send in the same tick, are bundled
          // by default).
          field.widgetOptionsJson.setAndSave({
            widget,
            // Persists color settings across widgets (note: we cannot use `field.fillColor` to get the
            // current value because it returns a default value for `undefined`. Same for `field.textColor`.
            fillColor: previous.fillColor,
            textColor: previous.textColor,
          }).catch(reportError);
        }
      }
    }));

    // Calculate common options for all column types (and their widgets).
    // We will use this, to know which options are allowed to be changed
    // when multiple columns are selected.
    const commonOptions = owner.autoDispose(ko.pureComputed(() => {
      const fields = this._fields();
      // Put all options of first widget in the Set, and then remove
      // them one by one, if they are not present in other fields.
      let options: Set<string>|null = null;
      for(const field of fields) {
        // First get the data, and prepare initial set.
        const widget = field.widget() || '';
        const widgetOptions = UserType.typeDefs[field.column().pureType()]?.widgets[widget]?.options;
        if (!widgetOptions) { continue; }
        if (!options) { options = new Set(Object.keys(widgetOptions)); }
        else {
          // And now remove options that are not common.
          const newOptions = new Set(Object.keys(widgetOptions));
          for(const key of options) {
            if (!newOptions.has(key)) {
              options.delete(key);
            }
          }
        }
      }
      // Add cell style options, as they are common to all widgets.
      const result = options ?? new Set();
      result.add('textColor');
      result.add('fillColor');
      result.add('fontBold');
      result.add('fontItalic');
      result.add('fontUnderline');
      result.add('fontStrikethrough');
      result.add('rulesOptions');
      // We are leaving rules out for this moment, as this is not supported
      // at this moment.
      return result;
    }));

    // Prepare our "multi" widgetOptionsJson, that can read and save
    // options for multiple columns.
    const options = modelUtil.savingComputed({
      read: () => {
        // For one column, just proxy this to the field.
        if (!this.multiselect()) {
          return this._field.widgetOptionsJson();
        }
        // Assemble final json object.
        const result: any = {};
        // First get all widgetOption jsons from all columns/fields.
        const optionList = this._fields().map(f => f.widgetOptionsJson());
        // And fill only those that are common
        const common = commonOptions();
        for(const key of common) {
          // Setting null means that this options is there, but has no value.
          result[key] = null;
          // If all columns have the same value, use it.
          if (allSame(optionList.map(v => v[key]))) {
            result[key] = optionList[0][key] ?? null;
          }
        }
        return result;
      },
      write: (setter, value) => {
        if (!this.multiselect.peek()) {
          return setter(this._field.widgetOptionsJson, value);
        }
        // When the creator panel is saving widgetOptions, it will pass
        // our virtual widgetObject, which has nulls for mixed values.
        // If this option wasn't changed (set), we don't want to save it.
        value = {...value};
        for(const key of Object.keys(value)) {
          if (value[key] === null) {
            delete value[key];
          }
        }
        // Now update all options, for all fields, be amending the options
        // object from the field/column.
        for(const item of this._fields.peek()) {
          const previous = item.widgetOptionsJson.peek();
          setter(item.widgetOptionsJson, {
            ...previous,
            ...value,
          });
        }
      }
    });

    // We need some additional information about each property.
    this.options = owner.autoDispose(extendObservable(modelUtil.objObservable(options), {
      // Property is not supported by set of columns if it is not a common option.
      disabled: prop => ko.pureComputed(() => !commonOptions().has(prop)),
      // Property has mixed value, if no all options are the same.
      mixed: prop => ko.pureComputed(() => !allSame(this._fields().map(f => f.widgetOptionsJson.prop(prop)()))),
      // Property has empty value, if all options are empty (are null, undefined, empty Array or empty Object).
      empty: prop => ko.pureComputed(() => allEmpty(this._fields().map(f => f.widgetOptionsJson.prop(prop)()))),
    }));

    // This is repeated logic for wrap property in viewFieldRec,
    // every field has wrapping implicitly set to true on a card view.
    this.wrap = modelUtil.fieldWithDefault(
      this.options.prop('wrap'),
      () => this._field.viewSection().parentKey() !== 'record'
    );

    // Some options extracted from our "virtual" widgetOptions json. Just to make
    // them easier to use in the rest of the app.
    this.alignment = this.options.prop('alignment');
    this.textColor = this.options.prop('textColor');
    this.fillColor = this.options.prop('fillColor');
    this.fontBold = this.options.prop('fontBold');
    this.fontUnderline = this.options.prop('fontUnderline');
    this.fontItalic = this.options.prop('fontItalic');
    this.fontStrikethrough = this.options.prop('fontStrikethrough');
  }

  // Helper for Choice/ChoiceList columns, that saves widget options and renames values in a document
  // in one bundle
  public async updateChoices(renames: Record<string, string>, options: any){
    const hasRenames = !!Object.entries(renames).length;
    const tableId = this._field.column.peek().table.peek().tableId.peek();
    if (this.multiselect.peek()) {
      this._field.config.options.update(options);
      const colIds = this._fields.peek().map(f => f.colId.peek());
      return this._docModel.docData.bundleActions("Update choices configuration", () => Promise.all([
        this._field.config.options.save(),
        !hasRenames ? null : this._docModel.docData.sendActions(
          colIds.map(colId => ["RenameChoices", tableId, colId, renames])
        )
      ]));
    } else {
      const column = this._field.column.peek();
      // In case this column is being transformed - using Apply Formula to Data, bundle the action
      // together with the transformation.
      const actionOptions = {nestInActiveBundle: column.isTransforming.peek()};
      this._field.widgetOptionsJson.update(options);
      return this._docModel.docData.bundleActions("Update choices configuration", () => Promise.all([
        this._field.widgetOptionsJson.save(),
        !hasRenames ? null
        : this._docModel.docData.sendAction(["RenameChoices", tableId, column.colId.peek(), renames])
      ]), actionOptions);
    }

  }

  // Two helper methods, to support reverting viewFields style on the style
  // picker. Style picker is reverting options by remembering what was
  // there previously, and setting it back when user presses the cancel button.
  // This won't work for mixed values, as there is no previous single value.
  // To support this reverting mechanism, we will remember all styles for
  // selected fields, and revert them ourselves. Style picker will either use
  // our methods or fallback with its default behavior.
  public copyStyles() {
    return this._fields.peek().map(f => f.style.peek());
  }
  public setStyles(styles: Style[]|null) {
    if (!styles) {
      return;
    }
    for(let i = 0; i < this._fields.peek().length; i++) {
      const f = this._fields.peek()[i];
      f.style(styles[i]);
    }
  }
}

/**
 * Deeply checks that all elements in a list are equal. Equality is checked by first
 * converting "empty like" elements to null and then deeply comparing the elements.
 */
function allSame(arr: any[]) {
  if (arr.length <= 1) { return true; }
  const first = ifNotSet(arr[0], null);
  const same = arr.every(next => {
    return isEqual(ifNotSet(next, null), first);
  });
  return same;
}

/**
 * Checks if every item in a list is empty (empty like in empty string, null, undefined, empty Array or Object)
 */
function allEmpty(arr: any[]) {
  if (arr.length === 0) { return true; }
  return arr.every(item => ifNotSet(item, null) === null);
}

type CommonOptions = modelUtil.SaveableObjObservable<any> & {
  disabled(prop: string): ko.Computed<boolean>,
  mixed(prop: string): ko.Computed<boolean>,
  empty(prop: string): ko.Computed<boolean>,
}

// This is helper that adds disabled computed to an ObjObservable, it follows
// the same pattern as `prop` helper.
function extendObservable(
  obs: modelUtil.SaveableObjObservable<any>,
  options: { [key: string]: (prop: string) => ko.PureComputed<boolean> }
): CommonOptions {
  const result = obs as any;
  for(const key of Object.keys(options)) {
    const cacheKey = `__${key}`;
    result[cacheKey] = new Map();
    result[key] = (prop: string) => {
      if (!result[cacheKey].has(prop)) {
        result[cacheKey].set(prop, options[key](prop));
      }
      return result[cacheKey].get(prop);
    };
  }

  return result;
}