import { YAML } from "$sb/syscalls.ts";
import { LintDiagnostic } from "$sb/types.ts";
import {
  findNodeOfType,
  renderToText,
  traverseTreeAsync,
} from "$sb/lib/tree.ts";
import { LintEvent } from "$sb/app_event.ts";

export async function lintYAML({ tree }: LintEvent): Promise<LintDiagnostic[]> {
  const diagnostics: LintDiagnostic[] = [];
  await traverseTreeAsync(tree, async (node) => {
    if (node.type === "FrontMatterCode") {
      const lintResult = await lintYaml(
        renderToText(node),
        node.from!,
      );
      if (lintResult) {
        diagnostics.push(lintResult);
      }
      return true;
    }
    if (node.type === "FencedCode") {
      const codeInfo = findNodeOfType(node, "CodeInfo")!;
      if (!codeInfo) {
        return true;
      }
      const codeLang = codeInfo.children![0].text!;
      // All known YAML formats
      if (
        codeLang === "template" || codeLang === "yaml" ||
        codeLang.startsWith("#")
      ) {
        const codeText = findNodeOfType(node, "CodeText");
        if (!codeText) {
          return true;
        }
        const yamlCode = renderToText(codeText);
        const lintResult = await lintYaml(
          yamlCode,
          codeText.from!,
        );
        if (lintResult) {
          diagnostics.push(lintResult);
        }
        return true;
      }
    }
    return false;
  });
  return diagnostics;
}

const errorRegex = /\((\d+):(\d+)\)/;

async function lintYaml(
  yamlText: string,
  from: number,
): Promise<LintDiagnostic | undefined> {
  try {
    await YAML.parse(yamlText);
  } catch (e) {
    const errorMatch = errorRegex.exec(e.message);
    if (errorMatch) {
      console.log("YAML error", e.message);
      const line = parseInt(errorMatch[1], 10) - 1;
      const yamlLines = yamlText.split("\n");
      let pos = from;
      for (let i = 0; i < line; i++) {
        pos += yamlLines[i].length + 1;
      }
      const endPos = pos + yamlLines[line]?.length || pos;

      return {
        from: pos,
        to: endPos,
        severity: "error",
        message: e.message,
      };
    }
  }
}