import {
  BsDatepickerState, initialDatepickerState
} from './bs-datepicker.state';
import { Action } from '../../mini-ngrx/index';
import { BsDatepickerActions } from './bs-datepicker.actions';
import { calcDaysCalendar } from '../engine/calc-days-calendar';
import { formatDaysCalendar } from '../engine/format-days-calendar';
import { flagDaysCalendar } from '../engine/flag-days-calendar';
import { shiftDate, setDate } from '../../bs-moment/utils/date-setters';
import { canSwitchMode } from '../engine/view-mode';
import { formatMonthsCalendar } from '../engine/format-months-calendar';
import { flagMonthsCalendar } from '../engine/flag-months-calendar';
import {
  formatYearsCalendar, yearsPerCalendar
} from '../engine/format-years-calendar';
import { flagYearsCalendar } from '../engine/flag-years-calendar';
import { BsViewNavigationEvent, DatepickerFormatOptions } from '../models/index';
import { isArray } from '../../bs-moment/utils/type-checks';
import { startOf } from '../../bs-moment/utils/start-end-of';

export function bsDatepickerReducer(state = initialDatepickerState, action: Action): BsDatepickerState {
  switch (action.type) {
    case(BsDatepickerActions.CALCULATE): {
      return calculateReducer(state);
    }

    case(BsDatepickerActions.FORMAT): {
      return formatReducer(state, action);
    }

    case(BsDatepickerActions.FLAG): {
      return flagReducer(state, action);
    }

    case(BsDatepickerActions.NAVIGATE_OFFSET): {
      const date = shiftDate(startOf(state.view.date, 'month'), action.payload);
      const newState = {
        view: {
          mode: state.view.mode,
          date
        }
      };

      return Object.assign({}, state, newState);
    }

    case(BsDatepickerActions.NAVIGATE_TO): {
      const payload: BsViewNavigationEvent = action.payload;

      const date = setDate(state.view.date, payload.unit);
      const mode = payload.viewMode;
      const newState = {view: {date, mode}};

      return Object.assign({}, state, newState);
    }

    case(BsDatepickerActions.CHANGE_VIEWMODE): {
      if (!canSwitchMode(action.payload)) {
        return state;
      }
      const date = state.view.date;
      const mode = action.payload;
      const newState = {view: {date, mode}};

      return Object.assign({}, state, newState);
    }

    case(BsDatepickerActions.HOVER): {
      return Object.assign({}, state, {hoveredDate: action.payload});
    }

    case(BsDatepickerActions.SELECT): {
      const newState = {
        selectedDate: action.payload,
        view: state.view
      };

      if (action.payload) {
        newState.view = {
          date: action.payload,
          mode: state.view.mode
        };
      }

      return Object.assign({}, state, newState);
    }

    case(BsDatepickerActions.SET_OPTIONS): {
      const newState = action.payload;
      // looks not really good
      if (newState.value) {
        newState.view = state.view;
        if (isArray(newState.value)) {
          newState.view = {
            mode: state.view.mode,
            date: newState.value[0]
          };
          newState.selectedRange = newState.value;
        } else {
          newState.view = {
            mode: state.view.mode,
            date: newState.value
          };
          newState.selectedDate = newState.value;
        }
      }

      return Object.assign({}, state, newState);
    }

    // date range picker
    case(BsDatepickerActions.SELECT_RANGE): {
      return Object.assign({}, state, {selectedRange: action.payload});
    }

    case(BsDatepickerActions.SET_MIN_DATE): {
      return Object.assign({}, state, {
        minDate: action.payload
      });
    }
    case(BsDatepickerActions.SET_MAX_DATE): {
      return Object.assign({}, state, {
        maxDate: action.payload
      });
    }
    case(BsDatepickerActions.SET_IS_DISABLED): {
      return Object.assign({}, state, {
        isDisabled: action.payload
      });
    }

    default:
      return state;
  }
}

function calculateReducer(state: BsDatepickerState): BsDatepickerState {
  // how many calendars
  const displayMonths = state.displayMonths;
  // use selected date on initial rendering if set
  let viewDate = state.view.date;

  if (state.view.mode === 'day') {
    const monthsModel = new Array(displayMonths);
    for (let monthIndex = 0; monthIndex < displayMonths; monthIndex++) {
      // todo: for unlinked calendars it will be harder
      monthsModel[monthIndex] = calcDaysCalendar(viewDate, state.monthViewOptions);
      viewDate = shiftDate(viewDate, {month: 1});
    }

    return Object.assign({}, state, {monthsModel});
  }

  if (state.view.mode === 'month') {
    const monthsCalendar = new Array(displayMonths);
    for (let calendarIndex = 0; calendarIndex < displayMonths; calendarIndex++) {
      // todo: for unlinked calendars it will be harder
      monthsCalendar[calendarIndex] = formatMonthsCalendar(viewDate, getFormatOptions(state));
      viewDate = shiftDate(viewDate, {year: 1});
    }

    return Object.assign({}, state, {monthsCalendar});
  }

  if (state.view.mode === 'year') {
    const yearsCalendarModel = new Array(displayMonths);

    for (let calendarIndex = 0; calendarIndex < displayMonths; calendarIndex++) {
      // todo: for unlinked calendars it will be harder
      yearsCalendarModel[calendarIndex] = formatYearsCalendar(viewDate, getFormatOptions(state));
      viewDate = shiftDate(viewDate, {year: yearsPerCalendar});
    }

    return Object.assign({}, state, {yearsCalendarModel});
  }

  return state;
}

function formatReducer(state: BsDatepickerState, action: Action): BsDatepickerState {
  if (state.view.mode === 'day') {
    const formattedMonths = state.monthsModel
      .map((month, monthIndex) => formatDaysCalendar(month, getFormatOptions(state), monthIndex));

    return Object.assign({}, state, {formattedMonths});
  }

  // how many calendars
  const displayMonths = state.displayMonths;
  // check initial rendering
  // use selected date on initial rendering if set
  let viewDate = state.view.date;

  if (state.view.mode === 'month') {
    const monthsCalendar = new Array(displayMonths);
    for (let calendarIndex = 0; calendarIndex < displayMonths; calendarIndex++) {
      // todo: for unlinked calendars it will be harder
      monthsCalendar[calendarIndex] = formatMonthsCalendar(viewDate, getFormatOptions(state));
      viewDate = shiftDate(viewDate, {year: 1});
    }

    return Object.assign({}, state, {monthsCalendar});
  }

  if (state.view.mode === 'year') {
    const yearsCalendarModel = new Array(displayMonths);
    for (let calendarIndex = 0; calendarIndex < displayMonths; calendarIndex++) {
      // todo: for unlinked calendars it will be harder
      yearsCalendarModel[calendarIndex] = formatYearsCalendar(viewDate, getFormatOptions(state));
      viewDate = shiftDate(viewDate, {year: 16});
    }

    return Object.assign({}, state, {yearsCalendarModel});
  }

  return state;
}

function flagReducer(state: BsDatepickerState, action: Action): BsDatepickerState {
  if (state.view.mode === 'day') {
    const flaggedMonths = state.formattedMonths
      .map((formattedMonth, monthIndex) => flagDaysCalendar(formattedMonth, {
        isDisabled: state.isDisabled,
        minDate: state.minDate,
        maxDate: state.maxDate,
        hoveredDate: state.hoveredDate,
        selectedDate: state.selectedDate,
        selectedRange: state.selectedRange,
        displayMonths: state.displayMonths,
        monthIndex
      }));

    return Object.assign({}, state, {flaggedMonths});
  }

  if (state.view.mode === 'month') {
    const flaggedMonthsCalendar = state.monthsCalendar
      .map((formattedMonth, monthIndex) => flagMonthsCalendar(formattedMonth, {
        isDisabled: state.isDisabled,
        minDate: state.minDate,
        maxDate: state.maxDate,
        hoveredMonth: state.hoveredMonth,
        displayMonths: state.displayMonths,
        monthIndex
      }));

    return Object.assign({}, state, {flaggedMonthsCalendar});
  }

  if (state.view.mode === 'year') {
    const yearsCalendarFlagged = state.yearsCalendarModel
      .map((formattedMonth, yearIndex) => flagYearsCalendar(formattedMonth, {
        isDisabled: state.isDisabled,
        minDate: state.minDate,
        maxDate: state.maxDate,
        hoveredYear: state.hoveredYear,
        displayMonths: state.displayMonths,
        yearIndex
      }));

    return Object.assign({}, state, {yearsCalendarFlagged});
  }

  return state;
}

function getFormatOptions(state: BsDatepickerState): DatepickerFormatOptions {
  return {
    locale: state.locale,

    monthTitle: state.monthTitle,
    yearTitle: state.yearTitle,

    dayLabel: state.dayLabel,
    monthLabel: state.monthLabel,
    yearLabel: state.yearLabel,

    weekNumbers: state.weekNumbers
  };
}