import React, { useState, useEffect } from 'react';
import { toast } from 'sonner';
import { api } from '@/api.js';
import { fmt } from '@/lib/utils';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Label } from '@/components/ui/label';
import {
  Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter,
} from '@/components/ui/dialog';

const MONTHS = [
  'January','February','March','April','May','June',
  'July','August','September','October','November','December',
];

function StartingAmountsEditDialog({ open, onClose, year, month, onSave }) {
  const [loading, setLoading] = useState(false);
  const [saving, setSaving] = useState(false);
  const [error, setError] = useState('');
  const [firstAmount, setFirstAmount] = useState('0');
  const [fifteenthAmount, setFifteenthAmount] = useState('0');
  const [otherAmount, setOtherAmount] = useState('0');
  const [preview, setPreview] = useState(null);

  const monthName = `${MONTHS[month - 1]} ${year}`;
  const localFirst = Number(firstAmount) || 0;
  const localFifteenth = Number(fifteenthAmount) || 0;
  const localOther = Number(otherAmount) || 0;
  const totalStarting = localFirst + localFifteenth + localOther;
  const paidSoFar = Number(preview?.paid_total || 0);
  const firstRemaining = localFirst - Number(preview?.paid_from_first || 0);
  const fifteenthRemaining = localFifteenth - Number(preview?.paid_from_fifteenth || 0);
  const totalRemaining = totalStarting - paidSoFar;

  useEffect(() => {
    let alive = true;
    async function loadStartingAmounts() {
      if (!open) return;
      setLoading(true);
      setError('');
      try {
        const result = await api.getMonthlyStartingAmounts(year, month);
        if (!alive) return;
        setPreview(result);
        setFirstAmount(String(result.first_amount ?? 0));
        setFifteenthAmount(String(result.fifteenth_amount ?? 0));
        setOtherAmount(String(result.other_amount ?? 0));
      } catch (err) {
        if (!alive) return;
        setError(err.message || 'Monthly starting amounts could not be loaded.');
      } finally {
        if (alive) setLoading(false);
      }
    }
    loadStartingAmounts();
    return () => { alive = false; };
  }, [open, year, month]);

  async function handleSave(e) {
    e.preventDefault();
    const first = Number(firstAmount);
    const fifteenth = Number(fifteenthAmount);
    const other = Number(otherAmount);
    if (![first, fifteenth, other].every(value => Number.isFinite(value) && value >= 0)) {
      setError('Starting amounts must be non-negative numbers.');
      return;
    }

    setSaving(true);
    setError('');
    try {
      await api.updateMonthlyStartingAmounts({
        year,
        month,
        first_amount: first,
        fifteenth_amount: fifteenth,
        other_amount: other,
      });
      toast.success('Monthly starting amounts saved.');
      onSave();
    } catch (err) {
      setError(err.message || 'Monthly starting amounts could not be saved.');
    } finally {
      setSaving(false);
    }
  }

  return (
    <Dialog open={open} onOpenChange={value => { if (!value) onClose(); }}>
      <DialogContent className="max-h-[92vh] overflow-y-auto border-border/60 bg-card/95 backdrop-blur-xl sm:max-w-lg">
        <DialogHeader>
          <DialogTitle className="text-lg font-semibold tracking-tight">Monthly Starting Amounts</DialogTitle>
          <p className="text-sm text-muted-foreground">{monthName}</p>
        </DialogHeader>

        <form id="starting-amounts-form" onSubmit={handleSave} className="space-y-5">
          {error && (
            <div className="rounded-lg border border-destructive/40 bg-destructive/10 px-3 py-2 text-sm text-destructive">
              {error}
            </div>
          )}

          <div className="grid gap-3 sm:grid-cols-3">
            <label className="space-y-1.5">
              <Label htmlFor="starting-first" className="text-xs uppercase tracking-wider text-muted-foreground">
                1st
              </Label>
              <Input
                id="starting-first"
                type="number"
                min="0"
                step="0.01"
                value={firstAmount}
                disabled={loading || saving}
                onChange={e => setFirstAmount(e.target.value)}
                className="font-mono bg-background/50 border-border/60"
              />
            </label>
            <label className="space-y-1.5">
              <Label htmlFor="starting-fifteenth" className="text-xs uppercase tracking-wider text-muted-foreground">
                15th
              </Label>
              <Input
                id="starting-fifteenth"
                type="number"
                min="0"
                step="0.01"
                value={fifteenthAmount}
                disabled={loading || saving}
                onChange={e => setFifteenthAmount(e.target.value)}
                className="font-mono bg-background/50 border-border/60"
              />
            </label>
            <label className="space-y-1.5">
              <Label htmlFor="starting-other" className="text-xs uppercase tracking-wider text-muted-foreground">
                Other
              </Label>
              <Input
                id="starting-other"
                type="number"
                min="0"
                step="0.01"
                value={otherAmount}
                disabled={loading || saving}
                onChange={e => setOtherAmount(e.target.value)}
                className="font-mono bg-background/50 border-border/60"
              />
            </label>
          </div>

          <div className="rounded-xl border border-border/60 bg-muted/35 p-4">
            <div className="grid gap-3 sm:grid-cols-3">
              <div>
                <p className="text-xs font-medium text-muted-foreground">Total starting</p>
                <p className="mt-1 font-mono text-lg font-bold">{fmt(totalStarting)}</p>
              </div>
              <div>
                <p className="text-xs font-medium text-muted-foreground">Paid so far</p>
                <p className="mt-1 font-mono text-lg font-bold text-emerald-500">{fmt(paidSoFar)}</p>
              </div>
              <div>
                <p className="text-xs font-medium text-muted-foreground">Total remaining</p>
                <p className="mt-1 font-mono text-lg font-bold">{fmt(totalRemaining)}</p>
              </div>
            </div>
            <div className="mt-4 grid gap-2 border-t border-border/60 pt-3 text-sm sm:grid-cols-3">
              <div className="flex justify-between gap-3 sm:block">
                <span className="text-muted-foreground">1st remaining</span>
                <span className="font-mono font-semibold sm:block">{fmt(firstRemaining)}</span>
              </div>
              <div className="flex justify-between gap-3 sm:block">
                <span className="text-muted-foreground">15th remaining</span>
                <span className="font-mono font-semibold sm:block">{fmt(fifteenthRemaining)}</span>
              </div>
              <div className="flex justify-between gap-3 sm:block">
                <span className="text-muted-foreground">Other</span>
                <span className="font-mono font-semibold sm:block">{fmt(localOther)}</span>
              </div>
            </div>
          </div>
        </form>

        <DialogFooter className="mt-2">
          <Button type="button" variant="ghost" disabled={saving} onClick={onClose} className="text-xs">
            Cancel
          </Button>
          <Button type="submit" form="starting-amounts-form" disabled={loading || saving} className="text-xs">
            {saving ? 'Saving...' : 'Save'}
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  );
}

export default StartingAmountsEditDialog;