import { useEffect, useState } from 'react';
import {
  Button,
  Checkbox,
  Divider,
  Drawer,
  MultiSelect,
  NumberInput,
  Select,
  Stack,
  Text,
  TextInput,
} from '@mantine/core';
import { useTranslation } from 'react-i18next';
import { BilingualInput, ModalFooter } from '@ema-platform/ui';
import type { ApplicationKind, DocumentRequirement, FormSchemaPalette } from '@ema-platform/api';
import { ConditionBuilder, type ConditionValue } from './ConditionBuilder';
import type { ConditionTarget } from '../config/schema-paths';

const MIME_OPTIONS = [
  { value: 'application/pdf', label: 'PDF' },
  { value: 'image/jpeg', label: 'JPEG' },
  { value: 'image/png', label: 'PNG' },
];

type DraftRequirement = Omit<DocumentRequirement, 'id' | 'licenseTypeId' | 'isActive'>;

function emptyDraft(applicationKind: ApplicationKind): DraftRequirement {
  return {
    key: '',
    name: { en: '', am: '' },
    applicationKind,
    mode: 'ALWAYS',
    allowedMimeTypes: ['application/pdf', 'image/jpeg', 'image/png'],
    maxSizeMb: 5,
    requiresValidityDates: false,
    allowMultiple: false,
    sortOrder: 0,
  };
}

/** Adds/edits one document requirement slot for a licence type + application kind. */
export function DocumentRequirementEditorDrawer({
  opened,
  onClose,
  requirement,
  defaultApplicationKind,
  onSave,
  palette,
  conditionTargets,
  saving,
}: {
  opened: boolean;
  onClose: () => void;
  /** Null = adding a new requirement. */
  requirement: DocumentRequirement | null;
  defaultApplicationKind: ApplicationKind;
  onSave: (draft: DraftRequirement) => void;
  palette: FormSchemaPalette | undefined;
  conditionTargets: ConditionTarget[];
  saving: boolean;
}) {
  const { t } = useTranslation();
  const [draft, setDraft] = useState<DraftRequirement>(emptyDraft(defaultApplicationKind));
  const [keyError, setKeyError] = useState<string | null>(null);
  const isNew = !requirement;

  useEffect(() => {
    if (opened) {
      setDraft(
        requirement
          ? {
              key: requirement.key,
              name: { ...requirement.name },
              description: requirement.description ? { ...requirement.description } : undefined,
              applicationKind: requirement.applicationKind,
              mode: requirement.mode,
              conditionExpression: requirement.conditionExpression,
              allowedMimeTypes: requirement.allowedMimeTypes,
              maxSizeMb: requirement.maxSizeMb,
              requiresValidityDates: requirement.requiresValidityDates,
              allowMultiple: requirement.allowMultiple,
              sortOrder: requirement.sortOrder,
            }
          : emptyDraft(defaultApplicationKind),
      );
      setKeyError(null);
    }
  }, [opened, requirement, defaultApplicationKind]);

  function save() {
    if (!draft.key.trim()) {
      setKeyError(t('certReq.doc.keyRequired', 'Key is required'));
      return;
    }
    if (!draft.name.en?.trim()) return;
    // A condition is either a single-field check or an anyOf list — the CoP
    // watch_rating_certificate requirement is seeded with anyOf and no field.
    const hasCondition =
      Boolean(draft.conditionExpression?.field) ||
      Boolean(draft.conditionExpression?.anyOf?.length);
    if (
      draft.mode === 'CONDITIONAL' &&
      !hasCondition &&
      !draft.conditionExpression?.anyOf?.length
    ) {
      setKeyError(t('certReq.doc.conditionRequired', 'A conditional requirement needs a condition'));
      return;
    }
    onSave({
      ...draft,
      key: draft.key.trim(),
      conditionExpression: draft.mode === 'CONDITIONAL' ? draft.conditionExpression : undefined,
    });
  }

  return (
    <Drawer
      opened={opened}
      onClose={onClose}
      position="right"
      size="md"
      title={<Text fw={700}>{isNew ? t('certReq.doc.add', 'Add document requirement') : t('certReq.doc.edit', 'Edit document requirement')}</Text>}
    >
      <Stack gap="md">
        <TextInput
          label={t('certReq.doc.key', 'Key')}
          placeholder="bank_letter"
          required
          value={draft.key}
          error={keyError}
          disabled={!isNew}
          description={isNew ? t('certReq.doc.keyHelp', 'Stable slug identifying this document slot') : t('certReq.doc.keyLocked', 'Key cannot change once created')}
          onChange={(e) => setDraft((d) => ({ ...d, key: e.currentTarget.value }))}
        />

        <BilingualInput
          label={t('certReq.doc.name', 'Name')}
          required
          value={{ en: draft.name.en ?? '', am: draft.name.am ?? '' }}
          onChange={(v) => setDraft((d) => ({ ...d, name: v }))}
        />

        <BilingualInput
          label={t('certReq.doc.description', 'Description')}
          value={{ en: draft.description?.en ?? '', am: draft.description?.am ?? '' }}
          onChange={(v) => setDraft((d) => ({ ...d, description: v }))}
        />

        <Select
          label={t('certReq.doc.applicationKind', 'Application kind')}
          data={[
            { value: 'NEW', label: t('certReq.doc.kindNew', 'New application') },
            { value: 'RENEWAL', label: t('certReq.doc.kindRenewal', 'Renewal') },
          ]}
          value={draft.applicationKind}
          onChange={(v) => v && setDraft((d) => ({ ...d, applicationKind: v as ApplicationKind }))}
          allowDeselect={false}
          disabled={!isNew}
          description={!isNew ? t('certReq.doc.kindLocked', 'Application kind cannot change once created') : undefined}
        />

        <Select
          label={t('certReq.doc.mode', 'Mode')}
          data={[
            { value: 'ALWAYS', label: t('certReq.doc.modeAlways', 'Always required') },
            { value: 'CONDITIONAL', label: t('certReq.doc.modeConditional', 'Required when condition holds') },
            { value: 'OPTIONAL', label: t('certReq.doc.modeOptional', 'Optional upload') },
          ]}
          value={draft.mode}
          onChange={(v) => v && setDraft((d) => ({ ...d, mode: v as DraftRequirement['mode'] }))}
          allowDeselect={false}
        />

        {draft.mode === 'CONDITIONAL' && (
          <>
            <Divider label={t('certReq.condition.title', 'Condition')} labelPosition="left" />
            <ConditionBuilder
              value={(draft.conditionExpression ?? { field: '', equals: '' }) as ConditionValue}
              onChange={(v) => setDraft((d) => ({ ...d, conditionExpression: v ?? undefined }))}
              targets={conditionTargets}
              palette={palette}
              allowClear={false}
            />
          </>
        )}

        <MultiSelect
          label={t('certReq.doc.allowedTypes', 'Allowed file types')}
          data={MIME_OPTIONS}
          value={draft.allowedMimeTypes}
          onChange={(v) => setDraft((d) => ({ ...d, allowedMimeTypes: v }))}
        />

        <NumberInput
          label={t('certReq.doc.maxSize', 'Max file size (MB)')}
          min={1}
          value={draft.maxSizeMb}
          onChange={(v) => setDraft((d) => ({ ...d, maxSizeMb: typeof v === 'number' ? v : d.maxSizeMb }))}
        />

        <Checkbox
          label={t('certReq.doc.requiresValidity', 'Requires validity dates')}
          checked={draft.requiresValidityDates}
          onChange={(e) => setDraft((d) => ({ ...d, requiresValidityDates: e.currentTarget.checked }))}
        />

        <Checkbox
          label={t('certReq.doc.allowMultiple', 'Allow multiple uploads')}
          checked={draft.allowMultiple}
          onChange={(e) => setDraft((d) => ({ ...d, allowMultiple: e.currentTarget.checked }))}
        />

        <NumberInput
          label={t('certReq.doc.sortOrder', 'Sort order')}
          value={draft.sortOrder}
          onChange={(v) => setDraft((d) => ({ ...d, sortOrder: typeof v === 'number' ? v : d.sortOrder }))}
        />

        <ModalFooter>
          <Button variant="default" onClick={onClose}>{t('certReq.cancel', 'Cancel')}</Button>
          <Button color="teal" loading={saving} onClick={save}>
            {isNew ? t('certReq.doc.add', 'Add document requirement') : t('certReq.saveChanges', 'Save changes')}
          </Button>
        </ModalFooter>
      </Stack>
    </Drawer>
  );
}