'use client';

import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import { useParams } from 'next/navigation';
import { CheckCircle2, ChevronRight } from 'lucide-react';

import { Checkbox } from '@/components/ui/checkbox';
import { Button } from '@/components/ui/button';
import { apiFetch } from '@/lib/api/client';
import { toastError } from '@/lib/api/toast-error';
import { cn } from '@/lib/utils';

interface QualificationRow {
  key: string;
  label: string;
  description: string | null;
  enabled: boolean;
  displayOrder: number;
  confirmed: boolean;
  confirmedAt: string | null;
  confirmedBy: string | null;
  notes: string | null;
}

interface QualificationResponse {
  data: {
    criteria: QualificationRow[];
    fullyQualified: boolean;
  };
}

/**
 * Per-interest qualification checklist. Hidden when the port has no
 * enabled criteria. When the rep has confirmed every enabled criterion AND
 * the deal is still in 'enquiry', a soft hint surfaces a Promote button
 * that advances the stage to 'qualified' through the standard transition
 * endpoint (no override; this is the canonical adjacent move).
 */
export function QualificationChecklist({
  interestId,
  currentStage,
}: {
  interestId: string;
  currentStage: string;
}) {
  const params = useParams<{ portSlug: string }>();
  const queryClient = useQueryClient();

  const { data, isLoading } = useQuery<QualificationResponse>({
    queryKey: ['interest-qualifications', interestId],
    queryFn: () => apiFetch(`/api/v1/interests/${interestId}/qualifications`),
  });

  const toggleMutation = useMutation({
    mutationFn: async (vars: { criterionKey: string; confirmed: boolean }) =>
      apiFetch(`/api/v1/interests/${interestId}/qualifications`, {
        method: 'PUT',
        body: { criterionKey: vars.criterionKey, confirmed: vars.confirmed },
      }),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['interest-qualifications', interestId] });
    },
    onError: (err) => toastError(err),
  });

  const promoteMutation = useMutation({
    mutationFn: async () =>
      apiFetch(`/api/v1/interests/${interestId}/stage`, {
        method: 'POST',
        body: { pipelineStage: 'qualified' },
      }),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['interests', interestId] });
      queryClient.invalidateQueries({ queryKey: ['interests'] });
    },
    onError: (err) => toastError(err),
  });

  if (isLoading) return null;
  if (!data) return null;
  const criteria = data.data.criteria;
  if (criteria.length === 0) return null;

  const fullyQualified = data.data.fullyQualified;
  const showPromoteHint = fullyQualified && currentStage === 'enquiry';
  // Avoid referencing `params` in the JSX so the unused destructure passes
  // strict noUnused checks; it stays available for future deep-link hooks.
  void params;

  return (
    <section className="rounded-lg border bg-card/40 p-4 space-y-3">
      <div className="flex items-center justify-between gap-3">
        <h3 className="text-sm font-semibold">Qualification</h3>
        {fullyQualified ? (
          <span className="inline-flex items-center gap-1 text-xs text-emerald-700">
            <CheckCircle2 className="size-3.5" aria-hidden />
            All confirmed
          </span>
        ) : (
          <span className="text-xs text-muted-foreground">
            {criteria.filter((c) => c.confirmed).length} of {criteria.length} confirmed
          </span>
        )}
      </div>

      <ul className="space-y-2">
        {criteria.map((c) => (
          <li key={c.key} className="flex items-start gap-2.5">
            <Checkbox
              id={`qual-${c.key}`}
              checked={c.confirmed}
              disabled={toggleMutation.isPending}
              onCheckedChange={(v) =>
                toggleMutation.mutate({ criterionKey: c.key, confirmed: v === true })
              }
              className="mt-0.5"
            />
            <label
              htmlFor={`qual-${c.key}`}
              className={cn(
                'flex-1 text-sm cursor-pointer',
                c.confirmed ? 'text-foreground' : 'text-foreground/90',
              )}
            >
              <span
                className={cn('font-medium', c.confirmed && 'line-through text-muted-foreground')}
              >
                {c.label}
              </span>
              {c.description ? (
                <p className="mt-0.5 text-xs text-muted-foreground">{c.description}</p>
              ) : null}
            </label>
          </li>
        ))}
      </ul>

      {showPromoteHint ? (
        <div className="flex items-center justify-between rounded-md border border-emerald-200 bg-emerald-50 px-3 py-2">
          <p className="text-xs text-emerald-800">
            All criteria confirmed — this lead is ready to qualify.
          </p>
          <Button
            type="button"
            size="sm"
            className="h-7 px-2.5 text-xs"
            disabled={promoteMutation.isPending}
            onClick={() => promoteMutation.mutate()}
          >
            Promote to Qualified
            <ChevronRight className="size-3.5" aria-hidden />
          </Button>
        </div>
      ) : null}
    </section>
  );
}