'use client';

import { useState } from 'react';
import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query';
import { useParams } from 'next/navigation';
import { CheckCircle2, ChevronDown, 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;
  autoSatisfied: boolean;
  /** Human-readable explanation of what data drove auto-satisfaction
   *  (e.g. "Desired: 60 × 25 × 6 ft"). Empty when not auto-satisfied. */
  evidence: string;
}

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();
  // When the checklist is fully confirmed, default to collapsed and let
  // the rep expand on demand. `null` means "follow the auto-default";
  // an explicit boolean reflects a rep click.
  const [manuallyExpanded, setManuallyExpanded] = useState(false);

  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';
  // Auto-collapse when fully confirmed — rep can expand to inspect.
  // Force-expanded whenever there's still an outstanding item.
  const expanded = manuallyExpanded || !fullyQualified;
  // 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">
      <button
        type="button"
        onClick={() => fullyQualified && setManuallyExpanded((v) => !v)}
        className={cn(
          'flex w-full items-center justify-between gap-3 rounded-sm focus:outline-none focus-visible:ring-2 focus-visible:ring-ring',
          fullyQualified ? 'cursor-pointer' : 'cursor-default',
        )}
        aria-expanded={expanded}
        aria-controls="qualification-checklist-body"
        disabled={!fullyQualified}
      >
        <span className="flex items-center gap-2">
          <h3 className="text-sm font-semibold">Qualification</h3>
          {fullyQualified && (
            <ChevronDown
              className={cn(
                'size-3.5 text-muted-foreground transition-transform',
                !expanded && '-rotate-90',
              )}
              aria-hidden
            />
          )}
        </span>
        {fullyQualified ? (
          <span className="inline-flex items-center gap-1 text-xs text-emerald-700">
            <CheckCircle2 className="size-3.5" aria-hidden />
            All confirmed
            {!expanded && criteria.length > 0 ? (
              <span className="ml-1 text-muted-foreground">
                ({criteria.map((c) => c.label.toLowerCase()).join(' · ')})
              </span>
            ) : null}
          </span>
        ) : (
          <span className="text-xs text-muted-foreground">
            {criteria.filter((c) => c.confirmed).length} of {criteria.length} confirmed
          </span>
        )}
      </button>

      {expanded ? (
        <ul id="qualification-checklist-body" className="space-y-1.5">
          {criteria.map((c) => (
            <li
              key={c.key}
              className={cn(
                'flex items-start gap-2.5 rounded-md px-2 py-1.5 transition-colors',
                // Unconfirmed rows get a subtle amber accent (left border +
                // tinted background) so reps can scan the checklist and
                // immediately see what's outstanding. Confirmed rows stay
                // muted with line-through; auto-satisfied rows are functionally
                // confirmed and follow the confirmed styling.
                !c.confirmed && 'border-l-2 border-warning bg-warning-bg/40',
              )}
            >
              <Checkbox
                id={`qual-${c.key}`}
                checked={c.confirmed}
                // Auto-satisfied rows can't be unchecked from the UI — the
                // underlying data signal would just re-tick the box on the next
                // refetch. The rep clears the dimensions tick by removing the
                // yacht dims or desired-berth dims from the interest.
                disabled={toggleMutation.isPending || c.autoSatisfied}
                onCheckedChange={(v) =>
                  toggleMutation.mutate({ criterionKey: c.key, confirmed: v === true })
                }
                className="mt-0.5"
              />
              <label
                htmlFor={`qual-${c.key}`}
                className={cn(
                  'flex-1 text-sm',
                  c.autoSatisfied ? 'cursor-default' : 'cursor-pointer',
                  c.confirmed ? 'text-muted-foreground' : 'text-foreground',
                )}
              >
                <span className="flex flex-wrap items-center gap-1.5">
                  <span
                    className={cn(
                      'font-medium',
                      c.confirmed && 'line-through text-muted-foreground',
                    )}
                  >
                    {c.label}
                  </span>
                  {c.autoSatisfied && (
                    <span
                      className="rounded bg-emerald-100 px-1.5 py-0.5 text-[10px] font-medium uppercase tracking-wide text-emerald-800 dark:bg-emerald-950 dark:text-emerald-200"
                      title="System-derived from data on this interest"
                    >
                      Auto
                    </span>
                  )}
                </span>
                {c.description ? (
                  <p className="mt-0.5 text-xs text-muted-foreground">{c.description}</p>
                ) : null}
                {c.autoSatisfied && c.evidence ? (
                  <p className="mt-0.5 text-xs font-medium text-emerald-700 dark:text-emerald-300">
                    {c.evidence}
                  </p>
                ) : null}
              </label>
            </li>
          ))}
        </ul>
      ) : null}

      {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>
  );
}
