import * as React from 'react';
import ReactQuill from 'react-quill';
import 'react-quill/dist/quill.snow.css';
import { Textarea } from '@/components/ui/textarea';
import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
import { Alert, AlertDescription } from '@/components/ui/alert';
import { Info } from 'lucide-react';
import { cn } from '@/components/ui/utils';

const quillModules = {
  toolbar: [
    [{ header: [1, 2, 3, false] }],
    ['bold', 'italic', 'underline'],
    [{ list: 'ordered' }, { list: 'bullet' }],
    ['link'],
    ['blockquote'],
    ['clean'],
  ],
};

const quillFormats = ['header', 'bold', 'italic', 'underline', 'list', 'bullet', 'link', 'blockquote'];

/** Handlebars helpers/partials or full HTML docs must be edited as source — rich editors strip or corrupt them. */
export function requiresAdvancedHtmlEditing(html: string): boolean {
  const s = html || '';
  return (
    /\{\{\s*[>#\/]/.test(s) ||
    /\{\{>\s*\w+/.test(s) ||
    /<!DOCTYPE/i.test(s) ||
    /<html[\s>]/i.test(s) ||
    /<\/html>/i.test(s) ||
    /<style\b/i.test(s) ||
    /<head[\s>]/i.test(s)
  );
}

export type EmailTemplateBodyEditorHandle = {
  insertPlaceholder: (placeholder: string) => void;
};

type Props = {
  value: string;
  onChange: (html: string) => void;
  /** visual | html */
  tab: string;
  onTabChange: (v: string) => void;
  textareaRef: React.RefObject<HTMLTextAreaElement>;
};

export const EmailTemplateBodyEditor = React.forwardRef<EmailTemplateBodyEditorHandle, Props>(
  ({ value, onChange, tab, onTabChange, textareaRef }, ref) => {
    const quillRef = React.useRef<ReactQuill>(null);
    const advanced = React.useMemo(() => requiresAdvancedHtmlEditing(value), [value]);

    React.useImperativeHandle(ref, () => ({
      insertPlaceholder: (placeholder: string) => {
        const token = `{{${placeholder}}}`;
        if (tab === 'html' && textareaRef.current) {
          const el = textareaRef.current;
          const start = el.selectionStart ?? 0;
          const end = el.selectionEnd ?? 0;
          const next = value.slice(0, start) + token + value.slice(end);
          onChange(next);
          requestAnimationFrame(() => {
            el.focus();
            const pos = start + token.length;
            el.setSelectionRange(pos, pos);
          });
          return;
        }
        const editor = quillRef.current?.getEditor?.();
        if (!editor) return;
        const range = editor.getSelection(true);
        const idx = range?.index ?? editor.getLength();
        editor.insertText(idx, token, 'user');
      },
    }));

    return (
      <div className="flex flex-col gap-2 flex-1 min-h-0">
        <Tabs value={tab} onValueChange={onTabChange} className="flex flex-col flex-1 gap-2 min-h-0">
          <TabsList className="w-fit">
            <TabsTrigger value="visual" disabled={advanced} className="text-xs">
              Rich text
            </TabsTrigger>
            <TabsTrigger value="html" className="text-xs font-mono">
              HTML source
            </TabsTrigger>
          </TabsList>

          {advanced && (
            <Alert className="border-amber-200 bg-amber-50 py-2">
              <Info className="h-4 w-4 text-amber-700" />
              <AlertDescription className="text-[11px] text-amber-900">
                This template uses layout partials (<code className="font-mono">{'{{> ...}}'}</code>), block helpers, or a full HTML
                document. Edit it in <strong>HTML source</strong> so nothing is stripped. Use placeholders on the left to insert
                fields safely.
              </AlertDescription>
            </Alert>
          )}

          <TabsContent value="visual" className="flex-1 flex flex-col gap-2 mt-2 min-h-[420px] data-[state=inactive]:hidden">
            <div
              className={cn(
                'email-quill rounded-md border border-slate-200 bg-white overflow-hidden flex flex-col flex-1',
                '[&_.ql-toolbar]:border-slate-200 [&_.ql-toolbar]:bg-slate-50',
                '[&_.ql-container]:border-0 [&_.ql-editor]:min-h-[380px] [&_.ql-editor]:text-sm [&_.ql-editor]:text-slate-900'
              )}
            >
              <ReactQuill
                ref={quillRef}
                theme="snow"
                value={value || ''}
                onChange={onChange}
                modules={quillModules}
                formats={quillFormats}
              />
            </div>
            <p className="text-[10px] text-slate-500">
              Use headings, lists, and links. Insert dynamic fields from <strong>Available Placeholders</strong> on the left.
            </p>
          </TabsContent>

          <TabsContent value="html" className="flex-1 flex flex-col mt-2 min-h-[420px] data-[state=inactive]:hidden">
            <Textarea
              ref={textareaRef}
              placeholder="Raw HTML / Handlebars — use for partials {{> ...}} or full layouts"
              className="flex-1 min-h-[420px] font-mono text-xs text-slate-900 bg-slate-900/5 focus:bg-white p-4 resize-y"
              value={value || ''}
              onChange={(e) => onChange(e.target.value)}
              spellCheck={false}
            />
            <p className="text-[10px] text-slate-500 mt-1">
              Full control for <code className="font-mono">{'{{> email_header}}'}</code>, styles, and edge cases. Backend still
              sanitizes on save.
            </p>
          </TabsContent>
        </Tabs>
      </div>
    );
  }
);

EmailTemplateBodyEditor.displayName = 'EmailTemplateBodyEditor';