import { build, stop, Plugin } from "https://deno.land/x/esbuild@v0.20.0/mod.js";
import {
  denoResolverPlugin,
  denoLoaderPlugin
} from "https://deno.land/x/esbuild_deno_loader@0.9.0/mod.ts";
import { gray } from "https://deno.land/std@0.215.0/fmt/colors.ts";
import { toFileUrl } from "https://deno.land/std@0.213.0/path/mod.ts";

/** keyが親ファイルパス, valueがそのファイルでimportしたファイルのパスリスト */
const ancestors = new Map<string, string[]>;
let entryPoint = "";

function* makeTree(
  parent: string,
  // parentからの相対URLで表示したいときtrue
  relative?: boolean,
  viewedPath?: Set<string>,
): Generator<string> {
  const childs = ancestors.get(parent);
  if (!childs) return;
  viewedPath ??= new Set<string>();
  viewedPath.add(parent);
  for (let i = 0; i < childs.length; i++) {
    const child = childs[i];
    const relativePath = decodeURIComponent(
      relative ? makeRelative(new URL(parent), new URL(child)) : child,
    );
    const lastOne = i + 1 === childs.length;
    const branch = lastOne ? "└─ " : "├─ ";
    // 一度読み込んだものは灰色で表示する
    if (viewedPath.has(child)) {
      yield `${branch}${gray(relativePath)}`;
      continue;
    }
    yield `${branch}${relativePath}`;
    viewedPath.add(child);
    const indent = lastOne ? "   " : "│  ";
    for (const line of makeTree(child, relative ?? false, viewedPath)) {
      yield `${indent}${line}`;
    }
  }
}

const listPlugin: Plugin = {
  name: "list-imports",
  setup: ({ onResolve, resolve }) => {
    onResolve({ filter: /.*/,  }, (args) => {
      /**
       * The following codes come from https://github.com/lucacasonato/esbuild_deno_loader/blob/0.9.0/src/plugin_deno_resolver.ts
       * Copyright (c) 2021 Luca Casonato. All rights reserved. MIT license.
       */
      // 
      // The first pass resolver performs synchronous resolution. This
      // includes relative to absolute specifier resolution and import map
      // resolution.

      // We have to first determine the referrer URL to use when resolving
      // the specifier. This is either the importer URL, or the resolveDir
      // URL if the importer is not specified (ie if the specifier is at the
      // root).
      let referrer: URL;
      if (args.importer !== "") {
        if (args.namespace === "") {
          throw new Error("[assert] namespace is empty");
        }
        referrer = new URL(`${args.namespace}:${args.importer}`);
      } else if (args.resolveDir !== "") {
        referrer = new URL(`${toFileUrl(args.resolveDir).href}/`);
      } else {
        return undefined;
      }

      // We can then resolve the specifier relative to the referrer URL. If
      // an import map is specified, we use that to resolve the specifier.
      const resolved = new URL(args.path, referrer);
      if (args.kind === "entry-point") {
        entryPoint = resolved.href;
      } else {
        ancestors.set(
          referrer.href,
          [...(ancestors.get(referrer.href) ?? []), resolved.href]
        );
      }
      return undefined;
    });
  },
};

await build({
  plugins: [listPlugin, denoResolverPlugin(), denoLoaderPlugin()],
  entryPoints: [Deno.args[0]],
  bundle: true,
  write: false,
  format: "esm",
  minify: true,
  charset: "utf8",
});
stop();

console.log(entryPoint);
for (const line of makeTree(entryPoint)) {
  console.log(line);
}