#!/usr/bin/env deno --allow-run --allow-write
// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
// This script formats the given source files. If the files are omitted, it
// formats the all files in the repository.
import {
  args,
  platform,
  readAll,
  lstat,
  exit,
  run,
  readFile,
  writeFile
} from "deno";
import { xrun } from "./util.ts";
import { parse } from "../flags/mod.ts";
import { prettier, prettierPlugins } from "./prettier.ts";

const HELP_MESSAGE = `
Formats the given files. If no arg is passed, then formats the all files.

Usage: deno prettier/main.ts [options] [files...]

Options:
  -H, --help                 Show this help message and exit.
  --check                    Check if the source files are formatted.
  --ignore <path>            Ignore the given path(s).

Example:
  deno prettier/main.ts script1.ts script2.js
                             Formats the files

  deno prettier/main.ts --check script1.ts script2.js
                             Checks if the files are formatted

  deno prettier/main.ts
                             Formats the all files in the repository
`;

// Available parsers
type ParserLabel = "typescript" | "babel" | "markdown" | "json";

const encoder = new TextEncoder();
const decoder = new TextDecoder();

// Lists files in the given directory.
// TODO: Replace git usage with deno's API calls
async function listFiles(dir: string = "."): Promise<string[]> {
  return decoder
    .decode(
      await readAll(
        xrun({
          args: ["git", "ls-files", dir],
          stdout: "piped"
        }).stdout
      )
    )
    .trim()
    .split(/\r?\n/);
}

async function getSourceFiles(args: string[]): Promise<string[]> {
  if (args.length === 0) {
    return listFiles();
  }

  const results = args.map(async path => {
    if ((await lstat(path)).isDirectory()) {
      return listFiles(path);
    }

    return path;
  });

  return [].concat(...(await Promise.all(results)));
}

// Filters out the files which contains any pattern in the given ignoreList.
function filterIgnoreList(files: string[], ignoreList: string[]) {
  return files.filter(path =>
    ignoreList.every(pattern => !path.includes(pattern))
  );
}

async function readFileIfExists(filename: string): Promise<string | null> {
  let data;
  try {
    data = await readFile(filename);
  } catch (e) {
    // The file is deleted. Returns null.
    return null;
  }

  return decoder.decode(data);
}

/**
 * Checks if the file has been formatted with prettier.
 */
async function checkFile(
  filename: string,
  parser: ParserLabel
): Promise<boolean> {
  const text = await readFileIfExists(filename);

  if (!text) {
    // The file is deleted. Skip.
    return;
  }

  const formatted = prettier.check(text, {
    parser,
    plugins: prettierPlugins
  });

  if (!formatted) {
    // TODO: print some diff info here to show why this failed
    console.error(`${filename} ... Not formatted`);
  }

  return formatted;
}

/**
 * Formats the given file.
 */
async function formatFile(
  filename: string,
  parser: ParserLabel
): Promise<void> {
  const text = await readFileIfExists(filename);

  if (!text) {
    // The file is deleted. Skip.
    return;
  }

  const formatted = prettier.format(text, {
    parser,
    plugins: prettierPlugins
  });

  if (text !== formatted) {
    console.log(`Formatting ${filename}`);
    await writeFile(filename, encoder.encode(formatted));
  }
}

/**
 * Selects the right prettier parser for the given path.
 */
function selectParser(path: string): ParserLabel | null {
  if (/\.ts$/.test(path)) {
    return "typescript";
  } else if (/\.js$/.test(path)) {
    return "babel";
  } else if (/\.json$/.test(path)) {
    return "json";
  } else if (/\.md$/.test(path)) {
    return "markdown";
  }

  return null;
}

/**
 * Checks if the files of the given paths have been formatted with prettier.
 * If paths are empty, then checks all the files.
 */
async function checkSourceFiles(
  args: string[],
  ignoreList: string[]
): Promise<void> {
  const checks = [];

  filterIgnoreList(await getSourceFiles(args), ignoreList).forEach(file => {
    const parser = selectParser(file);
    if (parser) {
      checks.push(checkFile(file, parser));
    }
  });

  const results = await Promise.all(checks);

  if (results.every(result => result)) {
    console.log("Every file is formatted");
    exit(0);
  } else {
    console.log("Some files are not formatted");
    exit(1);
  }
}

/**
 * Formats the files of the given paths with prettier.
 * If paths are empty, then formats all the files.
 */
async function formatSourceFiles(
  args: string[],
  ignoreList: string[]
): Promise<void> {
  const formats = [];

  filterIgnoreList(await getSourceFiles(args), ignoreList).forEach(file => {
    const parser = selectParser(file);
    if (parser) {
      formats.push(formatFile(file, parser));
    }
  });

  await Promise.all(formats);
  exit(0);
}

async function main(opts) {
  const { help, ignore, check, _: args } = opts;

  if (help) {
    console.log(HELP_MESSAGE);
    exit(0);
  }

  const ignoreList: string[] = Array.isArray(ignore) ? ignore : [ignore];

  try {
    if (check) {
      await checkSourceFiles(args, ignoreList);
    } else {
      await formatSourceFiles(args, ignoreList);
    }
  } catch (e) {
    console.log(e);
    exit(1);
  }
}

main(
  parse(args.slice(1), {
    string: ["ignore"],
    boolean: ["check", "help"],
    default: {
      ignore: []
    },
    alias: {
      H: "help"
    }
  })
);