import { visit } from 'unist-util-visit';
import type { Plugin } from 'unified';
import type { Root, PhrasingContent } from "mdast";

const alertRegex = /^\[!(NOTE|TIP|IMPORTANT|WARNING|CAUTION)\]/i;
const alertLegacyRegex = /^\[!(NOTE|TIP|IMPORTANT|WARNING|CAUTION)(\/.*)?\]/i;

type Option = {
  /**
   * Use the legacy title format, which includes a slash and a title after the alert type.
   * 
   * Enabling legacyTitle allows modifying the title, but this is not GitHub standard.
   */
  legacyTitle?: boolean;
  /**
   * The tag name of the alert container. default is `div`.
   * or you can use `blockquote` for semantic HTML.
   */
  tagName?: string;
}

/**
 * Alerts are a Markdown extension based on the blockquote syntax that you can use to emphasize critical information.
 * On GitHub, they are displayed with distinctive colors and icons to indicate the significance of the content.
 * https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax#alerts
 */
export const remarkAlert: Plugin<[Option?], Root> = ({ legacyTitle = false, tagName = "div" } = {}) => {
  return (tree) => {
    visit(tree, "blockquote", (node, index, parent) => {
      let alertType = '';
      let title = '';
      let isNext = true;
      let child = node.children.map((item) => {
        if (isNext && item.type === "paragraph") {
          const firstNode = item.children[0];
          const text = firstNode.type === 'text' ? firstNode.value : '';
          const reg = legacyTitle ? alertLegacyRegex : alertRegex;
          const match = text.match(reg);
          if (match) {
            isNext = false;
            alertType = match[1].toLocaleLowerCase();
            title = legacyTitle ? match[2] || alertType.toLocaleUpperCase() : alertType.toLocaleUpperCase();
            if (text.includes('\n')) {
              item.children[0] = {
                type: 'text',
                value: text.replace(reg, '').replace(/^\n+/, ''),
              };
            }

            if (!text.includes('\n')) {
              const itemChild: Array<PhrasingContent> = [];
              item.children.forEach((item, idx) => {
                if (idx == 0) return;
                if (idx == 1 && item.type === 'break') {
                  return;
                }
                itemChild.push(item);
              });
              item.children = [...itemChild];
            }
          }
        }
        return item;
      })

      if (!!alertType) {
        node.data = {
          hName: tagName,
          hProperties: {
            class: `markdown-alert markdown-alert-${alertType}`,
            dir: 'auto'
          },
        }
        child.unshift({
          type: "paragraph",
          children: [
            getAlertIcon(alertType as IconType),
            {
              type: "text",
              value: title.replace(/^\//, ''),
            }
          ],
          data: {
            hProperties: {
              class: "markdown-alert-title",
              dir: "auto"
            }
          }
        })
      }
      node.children = [...child];
    });
  };
};

export default remarkAlert;

export function getAlertIcon(type: IconType): PhrasingContent {
  let pathD = pathData[type] ?? '';
  return {
    type: "emphasis",
    data: {
      hName: "svg",
      hProperties: {
        class: "octicon",
        viewBox: '0 0 16 16',
        width: '16',
        height: '16',
        ariaHidden: 'true',
      },
    },
    children: [
      {
        type: "emphasis",
        data: {
          hName: "path",
          hProperties: {
            d: pathD
          }
        },
        children: []
      }
    ]
  }
}

type IconType = 'note' | 'tip' | 'important' | 'warning' | 'caution';

const pathData: Record<IconType, string> = {
  note: 'M0 8a8 8 0 1 1 16 0A8 8 0 0 1 0 8Zm8-6.5a6.5 6.5 0 1 0 0 13 6.5 6.5 0 0 0 0-13ZM6.5 7.75A.75.75 0 0 1 7.25 7h1a.75.75 0 0 1 .75.75v2.75h.25a.75.75 0 0 1 0 1.5h-2a.75.75 0 0 1 0-1.5h.25v-2h-.25a.75.75 0 0 1-.75-.75ZM8 6a1 1 0 1 1 0-2 1 1 0 0 1 0 2Z',
  tip: 'M8 1.5c-2.363 0-4 1.69-4 3.75 0 .984.424 1.625.984 2.304l.214.253c.223.264.47.556.673.848.284.411.537.896.621 1.49a.75.75 0 0 1-1.484.211c-.04-.282-.163-.547-.37-.847a8.456 8.456 0 0 0-.542-.68c-.084-.1-.173-.205-.268-.32C3.201 7.75 2.5 6.766 2.5 5.25 2.5 2.31 4.863 0 8 0s5.5 2.31 5.5 5.25c0 1.516-.701 2.5-1.328 3.259-.095.115-.184.22-.268.319-.207.245-.383.453-.541.681-.208.3-.33.565-.37.847a.751.751 0 0 1-1.485-.212c.084-.593.337-1.078.621-1.489.203-.292.45-.584.673-.848.075-.088.147-.173.213-.253.561-.679.985-1.32.985-2.304 0-2.06-1.637-3.75-4-3.75ZM5.75 12h4.5a.75.75 0 0 1 0 1.5h-4.5a.75.75 0 0 1 0-1.5ZM6 15.25a.75.75 0 0 1 .75-.75h2.5a.75.75 0 0 1 0 1.5h-2.5a.75.75 0 0 1-.75-.75Z',
  important:
    'M0 1.75C0 .784.784 0 1.75 0h12.5C15.216 0 16 .784 16 1.75v9.5A1.75 1.75 0 0 1 14.25 13H8.06l-2.573 2.573A1.458 1.458 0 0 1 3 14.543V13H1.75A1.75 1.75 0 0 1 0 11.25Zm1.75-.25a.25.25 0 0 0-.25.25v9.5c0 .138.112.25.25.25h2a.75.75 0 0 1 .75.75v2.19l2.72-2.72a.749.749 0 0 1 .53-.22h6.5a.25.25 0 0 0 .25-.25v-9.5a.25.25 0 0 0-.25-.25Zm7 2.25v2.5a.75.75 0 0 1-1.5 0v-2.5a.75.75 0 0 1 1.5 0ZM9 9a1 1 0 1 1-2 0 1 1 0 0 1 2 0Z',
  warning:
    'M6.457 1.047c.659-1.234 2.427-1.234 3.086 0l6.082 11.378A1.75 1.75 0 0 1 14.082 15H1.918a1.75 1.75 0 0 1-1.543-2.575Zm1.763.707a.25.25 0 0 0-.44 0L1.698 13.132a.25.25 0 0 0 .22.368h12.164a.25.25 0 0 0 .22-.368Zm.53 3.996v2.5a.75.75 0 0 1-1.5 0v-2.5a.75.75 0 0 1 1.5 0ZM9 11a1 1 0 1 1-2 0 1 1 0 0 1 2 0Z',
  caution:
    'M4.47.22A.749.749 0 0 1 5 0h6c.199 0 .389.079.53.22l4.25 4.25c.141.14.22.331.22.53v6a.749.749 0 0 1-.22.53l-4.25 4.25A.749.749 0 0 1 11 16H5a.749.749 0 0 1-.53-.22L.22 11.53A.749.749 0 0 1 0 11V5c0-.199.079-.389.22-.53Zm.84 1.28L1.5 5.31v5.38l3.81 3.81h5.38l3.81-3.81V5.31L10.69 1.5ZM8 4a.75.75 0 0 1 .75.75v3.5a.75.75 0 0 1-1.5 0v-3.5A.75.75 0 0 1 8 4Zm0 8a1 1 0 1 1 0-2 1 1 0 0 1 0 2Z',
};