import { 
    DayKey, DAY_KEYS, EXPENSE_TYPES, ExpenseRow, 
    SHIFT_TYPES, ShiftRow, make_hours, ShiftsHours, ExpensesAmount 
} from "./timesheet.types";
import { 
    isBetweenUTC, dayKeyFromDate, toTimeString, round2, 
    toUTCDateOnly, endOfDayUTC, addDays 
} from "./timesheet.helpers";
import { WeekDto, ShiftDto, TimesheetPeriodDto, DayExpensesDto, ExpenseDto } from "../dtos/timesheet-period.dto";
import { getWeekStart, getWeekEnd, formatDateISO } from "src/common/utils/date-utils";
import { makeAmounts, makeEmptyWeek } from "./timesheet.mappers";
import { toDateString }  from "src/modules/pay-periods/utils/pay-year.util";
import { MS_PER_HOUR } from "src/modules/shared/constants/date-time.constant";

    export function computeWeekRange(week_offset = 0){
        //sets current week Sunday -> Saturday
        const base   = new Date();
        const offset = new Date(base);
        offset.setDate(offset.getDate() + (week_offset * 7));

        const start = getWeekStart(offset, 0);
        const end   = getWeekEnd(start);
        const start_day       = formatDateISO(start);
        const end_day         = formatDateISO(end);
        const label = `${(start_day)}.${(end_day)}`;

        return { start, end, start_day, end_day, label }
    };

export function buildWeek( 
    week_start: Date,
    week_end:   Date,
    shifts:     ShiftRow[],
    expenses:   ExpenseRow[],
    ): WeekDto {
    const week = makeEmptyWeek(week_start);
    let all_approved = true;

    const day_times: Record<DayKey, Array<{ start: Date; end: Date }>> = DAY_KEYS.reduce((acc, key) => {
        acc[key] = []; return acc;
    }, {} as Record<DayKey, Array<{ start: Date; end: Date}>>);

    const day_hours: Record<DayKey, ShiftsHours> = DAY_KEYS.reduce((acc, key) => {
        acc[key] = make_hours(); return acc;
    }, {} as Record<DayKey, ShiftsHours>);

    const day_amounts: Record<DayKey, ExpensesAmount> = DAY_KEYS.reduce((acc, key) => {
        acc[key] = makeAmounts(); return acc;
    }, {} as Record<DayKey, ExpensesAmount>);

    const day_expense_rows: Record<DayKey, DayExpensesDto> = DAY_KEYS.reduce((acc, key) => {
        acc[key] = {
            expenses: [{
                type:    '',
                amount:  -1,
                mileage: -1,
                comment: '',
                is_approved: false,
                supervisor_comment: '',
            }],
            total_expense: -1,
            total_mileage: -1,
        };
        return acc;
    }, {} as Record<DayKey, DayExpensesDto>);

    //regroup hours per type of shifts
    const week_shifts = shifts.filter(shift => isBetweenUTC(shift.date, week_start, week_end));
    for (const shift of week_shifts) {
        const key = dayKeyFromDate(shift.date, true);
        week.shifts[key].shifts.push({
            date:        toDateString(shift.date),
            type:        shift.type,
            start_time:  toTimeString(shift.start_time),
            end_time:    toTimeString(shift.end_time),
            comment:     shift.comment,
            is_approved: shift.is_approved ?? true,
            is_remote:   shift.is_remote,
        } as ShiftDto);

        day_times[key].push({ start: shift.start_time, end: shift.end_time});

        const duration = Math.max(0, (shift.end_time.getTime() - shift.start_time.getTime())/ MS_PER_HOUR);
        const type = (shift.type || '').toUpperCase();

        if     ( type === SHIFT_TYPES.REGULAR)   day_hours[key].regular   += duration;
        else if( type === SHIFT_TYPES.EVENING)   day_hours[key].evening   += duration;
        else if( type === SHIFT_TYPES.EMERGENCY) day_hours[key].emergency += duration;
        else if( type === SHIFT_TYPES.OVERTIME)  day_hours[key].overtime  += duration;
        else if( type === SHIFT_TYPES.SICK)      day_hours[key].sick      += duration;
        else if( type === SHIFT_TYPES.VACATION)  day_hours[key].vacation  += duration;
        else if( type === SHIFT_TYPES.HOLIDAY)   day_hours[key].holiday   += duration;

        all_approved = all_approved && (shift.is_approved ?? true );
    }

    //regroupe amounts to type of expenses
    const week_expenses = expenses.filter(expense => isBetweenUTC(expense.date, week_start, week_end));
    for (const expense of week_expenses) {
        const key  = dayKeyFromDate(expense.date, true);
        const type = (expense.type || '').toUpperCase();

        const row: ExpenseDto = {
            type,
            amount:      round2(expense.amount ?? 0),
            mileage:     round2(expense.mileage ?? 0),
            comment:     expense.comment ?? '',
            is_approved: expense.is_approved ?? true,
            supervisor_comment: expense.supervisor_comment ?? '',
        };

        day_expense_rows[key].expenses.push(row);

        if(type === EXPENSE_TYPES.MILEAGE) {
            day_amounts[key].mileage += row.mileage ?? 0;
        } else {
            day_amounts[key].expense += row.amount;
        }

        all_approved = all_approved && row.is_approved;
    }

    for (const key of DAY_KEYS) {
        //return exposed dto data
        week.shifts[key].regular_hours   = round2(day_hours[key].regular);
        week.shifts[key].evening_hours   = round2(day_hours[key].evening);
        week.shifts[key].overtime_hours  = round2(day_hours[key].overtime);
        week.shifts[key].emergency_hours = round2(day_hours[key].emergency);

        //calculate gaps between shifts
        const times = day_times[key].sort((a,b) => a.start.getTime() - b.start.getTime());
        let gaps = 0;
        for (let i = 1; i < times.length; i++) {
            const gap = (times[i].start.getTime() - times[i - 1].end.getTime()) / MS_PER_HOUR;
            if(gap > 0) gaps += gap;
        }
        week.shifts[key].break_durations = round2(gaps);

        //daily totals
        const totals = day_amounts[key];

        day_expense_rows[key].total_mileage = round2(totals.mileage);
        day_expense_rows[key].total_expense = round2(totals.expense);
    }

    week.is_approved = all_approved;
    return week;
}

export function buildPeriod( 
    period_start: Date, 
    period_end: Date, 
    shifts: ShiftRow[], 
    expenses: ExpenseRow[],
    employeeFullName = ''
): TimesheetPeriodDto {
    const week1_start = toUTCDateOnly(period_start);
    const week1_end   = endOfDayUTC(addDays(week1_start, 6));
    const week2_start = toUTCDateOnly(addDays(week1_start, 7));
    const week2_end   = endOfDayUTC(period_end); 

    const weeks: WeekDto[] = [
        buildWeek(week1_start, week1_end, shifts, expenses),
        buildWeek(week2_start, week2_end, shifts, expenses),
    ];

    return {
        weeks,
        employee_full_name: employeeFullName,
    };
}