"use client";
import React, { useState, useRef, useEffect } from "react";
import { marked } from "marked";
import DOMPurify from "dompurify";
import { useI18n } from "@/lib/i18n";

interface MarkdownNoteEditorProps {
  value: string;
  onChange: (newValue: string) => void;
  onSave?: () => void;
}

export function MarkdownNoteEditor({ value, onChange, onSave }: MarkdownNoteEditorProps) {
  const { t } = useI18n();
  // Default to preview mode as requested
  const [mode, setMode] = useState<"edit" | "preview">("preview");
  const textareaRef = useRef<HTMLTextAreaElement>(null);
  const previewRef = useRef<HTMLDivElement>(null);

  // Reset to preview whenever value or active task changes
  useEffect(() => {
    // Keep preview mode as primary
  }, []);

  // Configure marked to open links in new tabs safely
  useEffect(() => {
    const renderer = new marked.Renderer();
    renderer.link = ({ href, title, text }: { href: string; title?: string | null; text: string }) => {
      const titleAttr = title ? ` title="${title}"` : "";
      return `<a href="${href}" target="_blank" rel="noopener noreferrer"${titleAttr} class="markdown-link">${text}</a>`;
    };
    marked.use({ renderer, breaks: true, gfm: true });
  }, []);

  // Keyboard shortcuts
  const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
    if ((e.ctrlKey || e.metaKey) && e.key === "s") {
      e.preventDefault();
      if (onSave) onSave();
    } else if (e.key === "Tab") {
      e.preventDefault();
      const ta = textareaRef.current;
      if (!ta) return;
      const start = ta.selectionStart;
      const end = ta.selectionEnd;
      const newVal = value.slice(0, start) + "  " + value.slice(end);
      onChange(newVal);
      requestAnimationFrame(() => {
        ta.selectionStart = ta.selectionEnd = start + 2;
      });
    }
  };

  // Convert markdown to sanitized HTML with safe links
  const renderMarkdownHtml = () => {
    if (!value || !value.trim()) {
      return `<div style="color: var(--text-tertiary); font-style: italic; user-select: none; line-height: 1.6;">${t("notesPlaceholder")}</div>`;
    }

    try {
      const textWithLinks = value.replace(
        /(^|[^"'])(https?:\/\/[^\s<]+)/g,
        (match, prefix, url) => {
          if (match.includes("](") || match.includes('href="')) return match;
          return `${prefix}[${url}](${url})`;
        }
      );

      const rawHtml = marked.parse(textWithLinks, { breaks: true, gfm: true }) as string;

      return DOMPurify.sanitize(rawHtml, {
        ALLOWED_TAGS: [
          "h1", "h2", "h3", "h4", "h5", "h6", "p", "a", "span", "strong", "em", "del", "s",
          "ul", "ol", "li", "code", "pre", "blockquote", "hr", "br", "table", "thead", "tbody",
          "tr", "th", "td"
        ],
        ALLOWED_ATTR: ["href", "title", "target", "rel", "class", "style"],
        ALLOWED_URI_REGEXP: /^(?:(?:https?|mailto):|[^a-z]|[a-z+.\-]+(?:[^a-z+.\-:]|$))/i,
        ADD_ATTR: ["target", "rel", "class"],
      });
    } catch {
      return value;
    }
  };

  return (
    <div
      style={{
        display: "flex",
        flexDirection: "column",
        height: "100%",
        width: "100%",
        minHeight: 0,
        position: "relative",
      }}
    >
      {/* Minimal Header with Mode Switcher */}
      <div
        style={{
          display: "flex",
          alignItems: "center",
          justifyContent: "space-between",
          padding: "4px 8px 8px 8px",
          flexShrink: 0,
        }}
      >
        <span style={{ fontSize: 11, fontWeight: 700, letterSpacing: "0.05em", color: "var(--text-tertiary)" }}>
          {t("notes").toUpperCase()}
        </span>

        {/* Minimal Matte One-touch Mode Toggle */}
        <button
          type="button"
          className="btn btn-ghost btn-sm"
          style={{
            fontSize: 11.5,
            padding: "2px 8px",
            height: 24,
            borderRadius: "var(--radius-sm)",
            border: "1px solid var(--border)",
            background: mode === "edit" ? "var(--accent-light)" : "var(--bg-secondary)",
            color: mode === "edit" ? "var(--accent)" : "var(--text-secondary)",
            fontWeight: 600,
            cursor: "pointer",
            transition: "all var(--dur-fast)",
          }}
          onClick={() => {
            if (mode === "preview") {
              setMode("edit");
              setTimeout(() => textareaRef.current?.focus(), 50);
            } else {
              setMode("preview");
            }
          }}
          title={mode === "preview" ? "Switch to Edit" : "Switch to Preview"}
        >
          {mode === "preview" ? "✏️ Edit" : "👁️ Preview"}
        </button>
      </div>

      {/* Editor / Preview Area */}
      <div
        style={{
          flex: 1,
          minHeight: 0,
          display: "flex",
          flexDirection: "column",
          position: "relative",
          background: "var(--bg-primary)",
          borderRadius: "var(--radius-md)",
          border: "1px solid var(--border)",
          overflow: "hidden",
        }}
      >
        {mode === "edit" ? (
          <textarea
            ref={textareaRef}
            className="note-editor-textarea"
            style={{
              flex: 1,
              width: "100%",
              height: "100%",
              padding: "10px 12px",
              background: "transparent",
              border: "none",
              outline: "none",
              color: "var(--text-primary)",
              fontSize: 13.5,
              lineHeight: 1.6,
              resize: "none",
              fontFamily: "inherit",
              boxSizing: "border-box",
            }}
            placeholder={t("notesPlaceholder")}
            value={value}
            onChange={(e) => onChange(e.target.value)}
            onKeyDown={handleKeyDown}
            onBlur={() => {
              if (onSave) onSave();
            }}
          />
        ) : (
          <div
            ref={previewRef}
            className="note-editor-preview"
            style={{
              flex: 1,
              width: "100%",
              height: "100%",
              padding: "10px 12px",
              overflowY: "auto",
              color: "var(--text-primary)",
              fontSize: 13.5,
              lineHeight: 1.6,
              boxSizing: "border-box",
              cursor: "text",
            }}
            dangerouslySetInnerHTML={{ __html: renderMarkdownHtml() }}
            onClick={() => {
              setMode("edit");
              setTimeout(() => textareaRef.current?.focus(), 50);
            }}
          />
        )}
      </div>
    </div>
  );
}