import unified from "unified";
import remarkParse from "remark-parse";
import remarkStringify from "remark-stringify";
// @ts-ignore
import mdastToString from "mdast-util-to-string";

export const BumpLevels = {
  dep: 0,
  patch: 1,
  minor: 2,
  major: 3
} as const;

export function getChangelogEntry(changelog: string, version: string) {
  let ast = unified()
    .use(remarkParse)
    .parse(changelog);

  let highestLevel: number = BumpLevels.dep;

  let nodes = ast.children as Array<any>;
  let headingStartInfo:
    | {
        index: number;
        depth: number;
      }
    | undefined;
  let endIndex: number | undefined;

  for (let i = 0; i < nodes.length; i++) {
    let node = nodes[i];
    if (node.type === "heading") {
      let stringified: string = mdastToString(node);
      let match = stringified.toLowerCase().match(/(major|minor|patch)/);
      if (match !== null) {
        let level = BumpLevels[match[0] as "major" | "minor" | "patch"];
        highestLevel = Math.max(level, highestLevel);
      }
      if (headingStartInfo === undefined && stringified === version) {
        headingStartInfo = {
          index: i,
          depth: node.depth
        };
        continue;
      }
      if (
        endIndex === undefined &&
        headingStartInfo !== undefined &&
        headingStartInfo.depth === node.depth
      ) {
        endIndex = i;
        break;
      }
    }
  }
  if (headingStartInfo) {
    ast.children = (ast.children as any).slice(
      headingStartInfo.index + 1,
      endIndex
    );
  }
  return {
    content: unified()
      .use(remarkStringify)
      .stringify(ast),
    highestLevel: highestLevel
  };
}