/**
 * Converts an EditorJS JSON output (string or object) into an HTML string.
 * Supports all block types used in the CMS blog editor.
 */
export function editorjsToHtml(raw: string | object | null | undefined): string {
  if (!raw) return "";

  let data: { blocks?: Array<{ type: string; data: Record<string, unknown> }> };

  if (typeof raw === "string") {
    try {
      data = JSON.parse(raw);
    } catch {
      // Not JSON — treat as plain HTML string (legacy content)
      return raw;
    }
  } else {
    data = raw as typeof data;
  }

  if (!data || !Array.isArray(data.blocks) || data.blocks.length === 0) {
    return "";
  }

  return data.blocks.map(renderBlock).join("\n");
}

function esc(text: unknown): string {
  return String(text ?? "")
    .replace(/&/g, "&amp;")
    .replace(/</g, "&lt;")
    .replace(/>/g, "&gt;")
    .replace(/"/g, "&quot;");
}

function renderBlock(block: { type: string; data: Record<string, unknown> }): string {
  const { type, data } = block;

  switch (type) {
    case "paragraph": {
      const text = data.text as string ?? "";
      return `<p>${text}</p>`;
    }

    case "header": {
      const level = Number(data.level) || 2;
      const tag = `h${Math.min(Math.max(level, 1), 6)}`;
      return `<${tag}>${data.text}</${tag}>`;
    }

    case "list": {
      const style = data.style === "ordered" ? "ol" : "ul";
      const items = (data.items as string[]) ?? [];
      const lis = items.map((item) => `<li>${item}</li>`).join("\n");
      return `<${style}>\n${lis}\n</${style}>`;
    }

    case "checklist": {
      const items = (data.items as Array<{ text: string; checked: boolean }>) ?? [];
      const lis = items
        .map(
          (item) =>
            `<li class="editorjs-checklist-item${item.checked ? " checked" : ""}">` +
            `<span class="editorjs-checkbox">${item.checked ? "✓" : "○"}</span> ${item.text}` +
            `</li>`
        )
        .join("\n");
      return `<ul class="editorjs-checklist">\n${lis}\n</ul>`;
    }

    case "image": {
      const file = (data.file as { url?: string }) ?? {};
      const url = file.url ?? (data.url as string) ?? "";
      const caption = (data.caption as string) ?? "";
      const stretched = data.stretched ? ' class="editorjs-image-stretched"' : "";
      const withBg = data.withBackground ? ' style="background:#f5f5f5; padding:1rem;"' : "";
      return (
        `<figure${withBg}>` +
        `<img src="${esc(url)}" alt="${esc(caption)}"${stretched} loading="lazy" />` +
        (caption ? `<figcaption>${caption}</figcaption>` : "") +
        `</figure>`
      );
    }

    case "quote": {
      const text = data.text as string ?? "";
      const caption = data.caption as string ?? "";
      return (
        `<blockquote class="editorjs-quote">` +
        `<p>${text}</p>` +
        (caption ? `<cite>${caption}</cite>` : "") +
        `</blockquote>`
      );
    }

    case "code": {
      return `<pre><code>${esc(data.code)}</code></pre>`;
    }

    case "delimiter": {
      return `<hr class="editorjs-delimiter" />`;
    }

    case "table": {
      const content = (data.content as string[][]) ?? [];
      const withHeadings = data.withHeadings as boolean;
      const rows = content.map((row, rowIdx) => {
        const tag = withHeadings && rowIdx === 0 ? "th" : "td";
        const cells = row.map((cell) => `<${tag}>${cell}</${tag}>`).join("");
        return `<tr>${cells}</tr>`;
      });
      return `<table class="editorjs-table">\n${rows.join("\n")}\n</table>`;
    }

    case "embed": {
      const service = (data.service as string ?? "").toLowerCase();
      const embedUrl = (data.embed as string) ?? "";
      const caption = (data.caption as string) ?? "";
      const width = (data.width as number) ?? 560;
      const height = (data.height as number) ?? 315;

      // EditorJS Embed stores the ready-to-use iframe src in data.embed
      let iframeSrc = esc(embedUrl);

      // Fallback: if data.embed is the watch URL, convert it
      if (service === "youtube" && iframeSrc.includes("watch?v=")) {
        iframeSrc = iframeSrc.replace("watch?v=", "embed/").split("&")[0];
      } else if (service === "vimeo" && !iframeSrc.includes("player.vimeo.com")) {
        const vimeoId = iframeSrc.split("/").pop() ?? "";
        iframeSrc = `https://player.vimeo.com/video/${vimeoId}`;
      }

      return (
        `<figure class="editorjs-embed">` +
        `<iframe src="${iframeSrc}" width="${width}" height="${height}" frameborder="0" allowfullscreen loading="lazy"></iframe>` +
        (caption ? `<figcaption>${caption}</figcaption>` : "") +
        `</figure>`
      );
    }


    default:
      // Unknown block — skip silently
      return "";
  }
}