import * as React from "react";
import moment from "moment";
import { success, error } from "../../toast/toast";
import {
  TaggedFarmEvent, SpecialStatus, TaggedSequence, TaggedRegimen,
  ParameterApplication,
} from "farmbot";
import { ExecutableQuery } from "../interfaces";
import { formatTime, formatDate } from "./map_state_to_props_add_edit";
import {
  BlurableInput,
  Col, Row,
  SaveBtn,
  FBSelect,
  DropDownItem,
  Help,
} from "../../ui";
import { destroy, save, overwrite } from "../../api/crud";
import { history } from "../../history";
import { betterMerge, parseIntInput } from "../../util";
import { maybeWarnAboutMissedTasks } from "./util";
import { FarmEventRepeatForm } from "./farm_event_repeat_form";
import { scheduleForFarmEvent } from "./calendar/scheduler";
import { executableType } from "../util";
import { Content } from "../../constants";
import { EventTimePicker } from "./event_time_picker";
import { TzWarning } from "./tz_warning";
import { nextRegItemTimes } from "./map_state_to_props";
import { first } from "lodash";
import {
  TimeUnit, ExecutableType, FarmEvent
} from "farmbot/dist/resources/api_resources";
import { LocalsList } from "../../sequences/locals_list/locals_list";
import { ResourceIndex } from "../../resources/interfaces";
import { ShouldDisplay } from "../../devices/interfaces";
import {
  addOrEditParamApps, variableList, getRegimenVariableData
} from "../../sequences/locals_list/variable_support";
import {
  AllowedVariableNodes,
} from "../../sequences/locals_list/locals_list_support";
import { t } from "../../i18next_wrapper";
import { TimeSettings } from "../../interfaces";
import { ErrorBoundary } from "../../error_boundary";

export const NEVER: TimeUnit = "never";
/** Separate each of the form fields into their own interface. Recombined later
 * on save.
 */
export interface FarmEventViewModel {
  id: number | undefined;
  startDate: string;
  startTime: string;
  endDate: string;
  endTime: string;
  repeat: string;
  timeUnit: string;
  executable_type: string;
  executable_id: string;
  timeSettings: TimeSettings;
  body?: ParameterApplication[];
}

export type FarmEventViewModelKey = keyof FarmEventViewModel;

/** Breaks up a TaggedFarmEvent into a structure that can easily be used
 * by the edit form.
 * USE CASE EXAMPLE: We have a "date" and "time" field that are created from
 *                   a single "start_time" FarmEvent field. */
export function destructureFarmEvent(
  fe: TaggedFarmEvent, timeSettings: TimeSettings): FarmEventViewModel {

  return {
    id: fe.body.id,
    startDate: formatDate((fe.body.start_time).toString(), timeSettings),
    startTime: formatTime((fe.body.start_time).toString(), timeSettings),
    endDate: formatDate((fe.body.end_time || new Date()).toString(), timeSettings),
    endTime: formatTime((fe.body.end_time || new Date()).toString(), timeSettings),
    repeat: (fe.body.repeat || 1).toString(),
    timeUnit: fe.body.time_unit,
    executable_type: fe.body.executable_type,
    executable_id: (fe.body.executable_id || "").toString(),
    timeSettings,
    body: fe.body.body,
  };
}

const startTimeWarning = () => {
  const message =
    t("Event start time needs to be in the future, not the past.");
  const title = t("Unable to save event.");
  error(message, title);
};

const nothingToRunWarning = () => {
  const message =
    t("All items scheduled before the start time. Nothing to run.");
  const title = t("Unable to save event.");
  error(message, title);
};

type RecombineOptions = { forceRegimensToMidnight: boolean };

/** Take a FormViewModel and recombine the fields into a FarmEvent
 * that can be used to apply updates (such as a PUT request to the API). */
export function recombine(vm: FarmEventViewModel,
  options: RecombineOptions): TaggedFarmEvent["body"] {
  // Make sure that `repeat` is set to `never` when dealing with regimens.
  const isReg = vm.executable_type === "Regimen";
  const startTime = isReg && options.forceRegimensToMidnight
    ? "00:00" : vm.startTime;
  return {
    id: vm.id,
    start_time: offsetTime(vm.startDate, startTime, vm.timeSettings),
    end_time: offsetTime(vm.endDate, vm.endTime, vm.timeSettings),
    repeat: parseInt(vm.repeat, 10) || 1,
    time_unit: (isReg ? "never" : vm.timeUnit) as TimeUnit,
    executable_id: parseIntInput(vm.executable_id),
    executable_type: vm.executable_type as ("Sequence" | "Regimen"),
    body: vm.body,
  };
}

export function offsetTime(
  date: string, time: string, timeSettings: TimeSettings): string {
  const out = moment(date).utcOffset(timeSettings.utcOffset);
  const [hrs, min] = time.split(":").map(x => parseInt(x));
  out.hours(hrs);
  out.minutes(min);
  return out.toISOString();
}

export interface EditFEProps {
  deviceTimezone: string | undefined;
  executableOptions: DropDownItem[];
  repeatOptions: DropDownItem[];
  farmEvent: TaggedFarmEvent;
  dispatch: Function;
  findExecutable: ExecutableQuery;
  title: string;
  deleteBtn?: boolean;
  timeSettings: TimeSettings;
  autoSyncEnabled: boolean;
  resources: ResourceIndex;
  shouldDisplay: ShouldDisplay;
}

export interface EditFEFormState {
  /**
   * Hold a partial FarmEvent locally containing only updates made by the form.
   */
  fe: Partial<FarmEventViewModel>;
  /**
   * This form has local state and does not cause any global state changes when
   * editing.
   *
   * Example: Navigating away from the page while editing will discard changes.
   */
  specialStatusLocal: SpecialStatus;
}

export class EditFEForm extends React.Component<EditFEProps, EditFEFormState> {
  state: EditFEFormState = { fe: {}, specialStatusLocal: SpecialStatus.SAVED };

  /** API data for the FarmEvent to which form updates can be applied. */
  get viewModel() {
    return destructureFarmEvent(this.props.farmEvent, this.props.timeSettings);
  }

  get executable() {
    const et = this.fieldGet("executable_type");
    const id = parseInt(this.fieldGet("executable_id"));
    if (et === "Sequence" || et === "Regimen") {
      return this.props.findExecutable(et, id);
    } else {
      throw new Error(`${et} is not a valid executable_type`);
    }
  }

  get isReg() {
    return this.fieldGet("executable_type") === "Regimen";
  }

  /** Executable requires variables or a user has manually added bodyVariables. */
  get needsVariables() {
    const varData = this.props.resources.sequenceMetas[this.executable.uuid];
    return Object.keys(varData || {}).length > 0;
  }

  get variableData() {
    if (this.executable.kind === "Regimen") {
      const regimenVariables = this.executable.body.body;
      return getRegimenVariableData(regimenVariables, this.props.resources);
    }
    return this.props.resources.sequenceMetas[this.executable.uuid];
  }

  get bodyVariables(): ParameterApplication[] {
    return this.state.fe.body || this.props.farmEvent.body.body || [];
  }

  overwriteStateFEBody = (newBody: ParameterApplication[]) => {
    const state = this.state;
    state.fe.body = newBody;
    this.setState(state);
  }

  editBodyVariables = (bodyVariables: ParameterApplication[]) =>
    (variable: ParameterApplication) => {
      const body = addOrEditParamApps(bodyVariables, variable);
      this.overwriteStateFEBody(body);
      this.setState({ specialStatusLocal: SpecialStatus.DIRTY });
    }

  LocalsList = () => <LocalsList
    bodyVariables={this.bodyVariables}
    variableData={this.variableData}
    sequenceUuid={this.executable.uuid}
    resources={this.props.resources}
    onChange={this.editBodyVariables(this.bodyVariables)}
    allowedVariableNodes={AllowedVariableNodes.variable}
    shouldDisplay={this.props.shouldDisplay} />

  executableSet = (ddi: DropDownItem) => {
    if (ddi.value) {
      const { id, executable_type } = this.props.farmEvent.body;
      const prev_executable_type = executable_type;
      const next_executable_type = executableType(ddi.headingId);
      if (id && prev_executable_type !== next_executable_type) {
        error(t("Cannot change between Sequences and Regimens."));
        history.push("/app/designer/events");
      } else {
        const { uuid } = this.props.findExecutable(
          next_executable_type, parseInt("" + ddi.value));
        const varData = this.props.resources.sequenceMetas[uuid];
        const update: EditFEFormState = {
          fe: {
            executable_type: next_executable_type,
            executable_id: (ddi.value || "").toString(),
          },
          specialStatusLocal: SpecialStatus.DIRTY
        };
        this.overwriteStateFEBody(variableList(varData) || []);
        this.setState(betterMerge(this.state, update));
      }
    }
  }

  executableGet = (): DropDownItem => {
    const headingId: ExecutableType =
      (this.executable.kind === "Sequence") ? "Sequence" : "Regimen";
    return {
      value: this.executable.body.id || 0,
      label: this.executable.body.name,
      headingId
    };
  }

  fieldSet = (key: FarmEventViewModelKey, value: string) =>
    // A merge is required to not overwrite `fe`.
    this.setState(betterMerge(this.state, {
      fe: { [key]: value },
      specialStatusLocal: SpecialStatus.DIRTY
    }))

  fieldGet = (key: FarmEventViewModelKey): string =>
    (this.state.fe[key] || this.viewModel[key] || "").toString()

  nextItemTime = (fe: FarmEvent, now: moment.Moment
  ): moment.Moment | undefined => {
    const { timeSettings } = this.props;
    const kind = fe.executable_type;
    const start = fe.start_time;
    const isRegimen = (x: TaggedSequence | TaggedRegimen): x is TaggedRegimen =>
      !!(x.kind === "Regimen");
    switch (kind) {
      case "Sequence":
        return first(scheduleForFarmEvent(fe, now).items);
      case "Regimen":
        const r = this.props.findExecutable(kind, fe.executable_id);
        const nextItem = isRegimen(r)
          ? first(nextRegItemTimes(r.body.regimen_items, start, now, timeSettings))
          : undefined;
        const futureStartTimeFallback = moment(start) > now
          ? moment(start)
          : undefined;
        return nextItem || futureStartTimeFallback;
      default:
        throw new Error(`${kind} is not a valid executable_type`);
    }
  }

  /** Rejects save of Farm Event if: */
  maybeRejectStartTime = (f: FarmEvent, now = moment()) => {
    /** adding a new event (editing repeats for ongoing events is allowed) */
    const newEvent = this.props.title.toLowerCase().includes("add");
    /** start time is in the past */
    const inThePast = moment(f.start_time) < now;
    /** is a sequence event */
    const sequenceEvent = !this.isReg;
    return newEvent && (inThePast && sequenceEvent);
  }

  /** Merge and recombine FarmEvent form updates into and updated FarmEvent. */
  get updatedFarmEvent() {
    /** ViewModel with INVALID `body` (must be replaced). */
    const vm = betterMerge(this.viewModel, this.state.fe);
    const oldBodyData = this.needsVariables ? this.viewModel.body : [];
    vm.body = this.state.fe.body || oldBodyData;
    const opts: RecombineOptions = { forceRegimensToMidnight: true };
    return recombine(vm, opts);
  }

  /** Use the next item run time to display toast messages. */
  nextRunTimeActions = (now = moment()) => {
    const nextRun = this.nextItemTime(this.props.farmEvent.body, now);
    if (nextRun) {
      const nextRunText = this.props.autoSyncEnabled
        ? t(`The next item in this event will run {{timeFromNow}}.`,
          { timeFromNow: nextRun.from(now) })
        : t(`The next item in this event will run {{timeFromNow}}, but
      you must first SYNC YOUR DEVICE. If you do not sync, the event will
      not run.`.replace(/\s+/g, " "), { timeFromNow: nextRun.from(now) });
      success(nextRunText);
    }
  }

  /**  Once saved, if
  *    - Regimen Farm Event:
  *      * If scheduled for today, warn about the possibility of missing tasks.
  *      * Display the start time difference from now and maybe prompt to sync.
  *      * Return to calendar view.
  *    - Sequence Farm Event:
  *      * Determine the time for the next item to be run.
  *      * If auto-sync is disabled, prompt the user to sync.
  *      * Return to calendar view.
  */
  commitViewModel = (now = moment()) => {
    if (this.maybeRejectStartTime(this.updatedFarmEvent)) {
      return startTimeWarning();
    }
    if (!this.nextItemTime(this.updatedFarmEvent, now)) {
      return nothingToRunWarning();
    }
    const { dispatch } = this.props;
    dispatch(overwrite(this.props.farmEvent, this.updatedFarmEvent));
    dispatch(save(this.props.farmEvent.uuid))
      .then(() => {
        this.setState({ specialStatusLocal: SpecialStatus.SAVED });
        dispatch(maybeWarnAboutMissedTasks(this.props.farmEvent,
          () => alert(t(Content.REGIMEN_TODAY_SKIPPED_ITEM_RISK)), now));
        this.nextRunTimeActions(now);
        history.push("/app/designer/events");
      })
      .catch(() => {
        error(t("Unable to save event."));
        this.setState({ specialStatusLocal: SpecialStatus.DIRTY });
      });
  }

  render() {
    const { farmEvent } = this.props;
    return <div className="edit-farm-event-form">
      <ErrorBoundary>
        <FarmEventForm
          isRegimen={this.isReg}
          fieldGet={this.fieldGet}
          fieldSet={this.fieldSet}
          timeSettings={this.props.timeSettings}
          executableOptions={this.props.executableOptions}
          executableSet={this.executableSet}
          executableGet={this.executableGet}
          dispatch={this.props.dispatch}
          specialStatus={farmEvent.specialStatus
            || this.state.specialStatusLocal}
          onSave={() => this.commitViewModel()}>
          <ErrorBoundary>
            <this.LocalsList />
          </ErrorBoundary>
        </FarmEventForm>
      </ErrorBoundary>
      <FarmEventDeleteButton
        hidden={!this.props.deleteBtn}
        farmEvent={this.props.farmEvent}
        dispatch={this.props.dispatch} />
      <TzWarning deviceTimezone={this.props.deviceTimezone} />
    </div>;
  }
}

export interface StartTimeFormProps {
  isRegimen: boolean;
  fieldGet(key: FarmEventViewModelKey): string;
  fieldSet(key: FarmEventViewModelKey, value: string): void;
  timeSettings: TimeSettings;
}

export const StartTimeForm = (props: StartTimeFormProps) => {
  const forceMidnight = props.isRegimen;
  return <div className="start-time-form">
    <label>
      {t("Starts")}
    </label>
    <Row>
      <Col xs={6}>
        <BlurableInput
          type="date"
          className="add-event-start-date"
          name="start_date"
          value={props.fieldGet("startDate")}
          onCommit={e => props.fieldSet("startDate", e.currentTarget.value)} />
      </Col>
      <Col xs={6}>
        <EventTimePicker
          className="add-event-start-time"
          name="start_time"
          timeSettings={props.timeSettings}
          value={props.fieldGet("startTime")}
          onCommit={e => props.fieldSet("startTime", e.currentTarget.value)}
          disabled={forceMidnight}
          hidden={forceMidnight} />
      </Col>
    </Row>
  </div>;
};

export interface RepeatFormProps {
  isRegimen: boolean;
  fieldGet(key: FarmEventViewModelKey): string;
  fieldSet(key: FarmEventViewModelKey, value: string): void;
  timeSettings: TimeSettings;
}

export const RepeatForm = (props: RepeatFormProps) => {
  const allowRepeat = !props.isRegimen && props.fieldGet("timeUnit") !== NEVER;
  return <div className="farm-event-repeat-options">
    {!props.isRegimen
      ? <label>
        <input type="checkbox"
          name="timeUnit"
          onChange={e => props.fieldSet("timeUnit",
            (!e.currentTarget.checked || props.isRegimen) ? "never" : "daily")}
          disabled={props.isRegimen}
          checked={allowRepeat} />
        {t("Repeats?")}
      </label>
      : <div className={"no-repeat"} />}
    <FarmEventRepeatForm
      timeSettings={props.timeSettings}
      disabled={!allowRepeat}
      hidden={!allowRepeat}
      fieldSet={props.fieldSet}
      timeUnit={props.fieldGet("timeUnit") as TimeUnit}
      repeat={props.fieldGet("repeat")}
      endDate={props.fieldGet("endDate")}
      endTime={props.fieldGet("endTime")}
      dateError={dateCheck(props.fieldGet)}
      timeError={timeCheck(props.fieldGet, props.timeSettings)} />
  </div>;
};

export const dateCheck = (
  fieldGet: (key: FarmEventViewModelKey) => string
): string | undefined => {
  const startDate = fieldGet("startDate");
  const endDate = fieldGet("endDate");
  if (!moment(endDate).isSameOrAfter(moment(startDate))) {
    return t("End date must not be before start date.");
  }
};

export const timeCheck = (
  fieldGet: (key: FarmEventViewModelKey) => string,
  timeSettings: TimeSettings
): string | undefined => {
  const startDate = fieldGet("startDate");
  const startTime = fieldGet("startTime");
  const endDate = fieldGet("endDate");
  const endTime = fieldGet("endTime");
  const start = offsetTime(startDate, startTime, timeSettings);
  const end = offsetTime(endDate, endTime, timeSettings);
  if (moment(start).isSameOrAfter(moment(end))) {
    return t("End time must be after start time.");
  }
};

export interface FarmEventDeleteButtonProps {
  hidden: boolean;
  farmEvent: TaggedFarmEvent;
  dispatch: Function;
}

export const FarmEventDeleteButton = (props: FarmEventDeleteButtonProps) =>
  <button className="fb-button red" hidden={props.hidden}
    title={t("Delete")}
    onClick={() =>
      props.dispatch(destroy(props.farmEvent.uuid))
        .then(() => {
          history.push("/app/designer/events");
          success(t("Deleted event."), t("Deleted"));
        })}>
    {t("Delete")}
  </button>;

export interface FarmEventFormProps {
  isRegimen: boolean;
  fieldGet(key: FarmEventViewModelKey): string;
  fieldSet(key: FarmEventViewModelKey, value: string): void;
  timeSettings: TimeSettings;
  executableOptions: DropDownItem[];
  executableSet(ddi: DropDownItem): void;
  executableGet(): DropDownItem | undefined;
  dispatch: Function;
  specialStatus: SpecialStatus;
  onSave(): void;
  children?: React.ReactChild;
}

export const FarmEventForm = (props: FarmEventFormProps) => {
  const { isRegimen, fieldGet, fieldSet, timeSettings } = props;
  return <div className="farm-event-form">
    <label>
      {t("Sequence or Regimen")}
    </label>
    {props.executableOptions.length < 1 &&
      <Help
        text={Content.MISSING_EXECUTABLE}
        customIcon={"exclamation-triangle"} />}
    <FBSelect
      list={props.executableOptions}
      onChange={props.executableSet}
      selectedItem={props.executableGet()} />
    {props.children}
    <StartTimeForm
      isRegimen={isRegimen}
      fieldGet={fieldGet}
      fieldSet={fieldSet}
      timeSettings={timeSettings} />
    <RepeatForm
      isRegimen={isRegimen}
      fieldGet={fieldGet}
      fieldSet={fieldSet}
      timeSettings={props.timeSettings} />
    <SaveBtn
      status={props.specialStatus}
      onClick={props.onSave} />
  </div>;
};