/***********************************************************************************************************************************************************************
 * File Name    : DeadlinePicker.jsx
 * Type         : Reusable Component
 * Description  : Combined date + time picker for deadline fields.
 *                Controlled via a single ISO datetime string (value / onChange).
 *                Calendar + time input live inside a Card, matching shadcn's
 *                "Date and Time Picker" pattern.
 *
 * Props:
 *   value    : string | null   — ISO datetime string e.g. "2026-06-01T10:30"
 *   onChange : (iso: string | null) => void
 *   disabled?: boolean
 ***********************************************************************************************************************************************************************/
import { useState } from 'react';
import { format, parseISO, isValid } from 'date-fns';
import { ChevronDownIcon, Clock2Icon } from 'lucide-react';

import { Button } from '@/components/ui/button';
import { Calendar } from '@/components/ui/calendar';
import { Card, CardContent, CardFooter } from '@/components/ui/card';
import { Field, FieldGroup, FieldLabel } from '@/components/ui/field';
import { InputGroup, InputGroupAddon, InputGroupInput } from '@/components/ui/input-group';
import { Popover, PopoverContent, PopoverTrigger } from '@/components/ui/popover';

// ── Helpers ───────────────────────────────────────────────────────────────────
function toDate(iso) {
    if (!iso) return undefined;
    const d = parseISO(iso);
    return isValid(d) ? d : undefined;
}

function toTimeString(iso) {
    if (!iso) return '00:00';
    const d = parseISO(iso);
    if (!isValid(d)) return '00:00';
    return format(d, 'HH:mm');
}

function buildISO(date, timeStr) {
    if (!date) return null;
    const [h = '00', m = '00'] = (timeStr ?? '00:00').split(':');
    const d = new Date(date);
    d.setHours(Number(h), Number(m), 0, 0);
    return d.toISOString();
}

// ─────────────────────────────────────────────────────────────────────────────
export default function DeadlinePicker({ value, onChange, disabled = false }) {
    const [open, setOpen] = useState(false);

    const selectedDate = toDate(value);
    const timeStr = toTimeString(value);

    const handleDateSelect = (date) => {
        onChange(buildISO(date, timeStr));
    };

    const handleTimeChange = (e) => {
        onChange(buildISO(selectedDate ?? new Date(), e.target.value));
    };

    const handleClear = () => onChange(null);

    return (
        <Popover open={open} onOpenChange={setOpen}>
            <PopoverTrigger asChild>
                <Button
                    type="button"
                    variant="outline"
                    disabled={disabled}
                    className="w-56 justify-between font-normal text-sm"
                >
                    {selectedDate
                        ? `${format(selectedDate, 'MMM d, yyyy')}  ${format(parseISO(buildISO(selectedDate, timeStr)), 'h:mm a')}`
                        : 'Select date'}
                    <ChevronDownIcon className="h-4 w-4 opacity-50" />
                </Button>
            </PopoverTrigger>
            <PopoverContent className="w-auto border-0 bg-transparent p-0 shadow-none ring-0" align="start">
                <Card size="sm" className="w-fit">
                    <CardContent>
                        <Calendar
                            mode="single"
                            selected={selectedDate}
                            captionLayout="dropdown"
                            defaultMonth={selectedDate}
                            onSelect={handleDateSelect}
                            disabled={disabled}
                            className="p-0"
                        />
                    </CardContent>
                    <CardFooter className="flex-col items-stretch gap-3 border-t bg-card">
                        <FieldGroup>
                            <Field orientation="horizontal">
                                <FieldLabel htmlFor="deadline-time">Time</FieldLabel>
                                <InputGroup>
                                    <InputGroupInput
                                        id="deadline-time"
                                        type="time"
                                        step="60"
                                        value={timeStr}
                                        onChange={handleTimeChange}
                                        disabled={disabled || !selectedDate}
                                        className="appearance-none [&::-webkit-calendar-picker-indicator]:hidden [&::-webkit-calendar-picker-indicator]:appearance-none"
                                    />
                                    <InputGroupAddon>
                                        <Clock2Icon className="text-muted-foreground" />
                                    </InputGroupAddon>
                                </InputGroup>
                            </Field>
                        </FieldGroup>
                        {value && (
                            <Button
                                type="button"
                                variant="outline"
                                size="sm"
                                disabled={disabled}
                                onClick={handleClear}
                            >
                                Clear
                            </Button>
                        )}
                    </CardFooter>
                </Card>
            </PopoverContent>
        </Popover>
    );
}