const pug = require("pug");
const sass = require("sass");
const fs = require("fs").promises;
const os = require("os");
const crypto = require("crypto");
const path = require("path");
const pj = path.join;
const babel = require("@babel/core");
const fetch = require("node-fetch");
const chalk = require("chalk");
const hint = require("jshint").JSHINT;

process.chdir(pj(__dirname, "src"));

const buildDir = "../build";

const validationQueue = [];
const validationHost =
  os.hostname() === "future"
    ? "http://localhost:8888/"
    : "http://validator.w3.org/nu/";
const static = new Map();
const links = new Map();
const pugLocals = { static, links };

const spec = require("./spec.js");

function hash(buffer) {
  return crypto.createHash("sha256").update(buffer).digest("hex").slice(0, 10);
}

function validate(filename, body, type) {
  const promise = fetch(validationHost + "?out=json", {
    method: "POST",
    body,
    headers: {
      "content-type": `text/${type}; charset=UTF-8`,
    },
  })
    .then((res) => res.json())
    .then((root) => {
      return function cont() {
        let concerningMessages = 0;
        for (const message of root.messages) {
          if (message.hiliteStart) {
            let type = message.type;
            if (message.type === "error") {
              type = chalk.red("error");
            } else if (message.type === "warning") {
              type = chalk.yellow("warning");
            } else {
              continue; // don't care about info
            }
            let match;
            if (
              (match = message.message.match(
                /Property “([\w-]+)” doesn't exist.$/
              ))
            ) {
              // allow these properties specifically
              if (
                [
                  "scrollbar-width",
                  "scrollbar-color",
                  "overflow-anchor",
                ].includes(match[1])
              ) {
                continue;
              }
            }
            concerningMessages++;
            console.log(`validation: ${type} in ${filename}`);
            console.log(`    ${message.message}`);
            const text = message.extract
              .replace(/\n/g, "⏎")
              .replace(/\t/g, " ");
            console.log(
              chalk.grey(
                "    " +
                  text.slice(0, message.hiliteStart) +
                  chalk.inverse(
                    text.substr(message.hiliteStart, message.hiliteLength)
                  ) +
                  text.slice(message.hiliteStart + message.hiliteLength)
              )
            );
          } else {
            console.log(message);
          }
        }
        if (!concerningMessages) {
          console.log(`validation: ${chalk.green("ok")} for ${filename}`);
        }
      };
    });
  validationQueue.push(promise);
  return promise;
}

function runHint(filename, source) {
  hint(source, {
    esversion: 9,
    undef: true,
    // unused: true,
    loopfunc: true,
    globals: ["console", "URLSearchParams"],
    browser: true,
    asi: true,
  });
  const result = hint.data();
  let problems = 0;
  if (result.errors) {
    for (const error of result.errors) {
      if (error.evidence) {
        const text = error.evidence.replace(/\t/g, "    ");
        if (["W014"].includes(error.code)) continue;
        let type = error.code.startsWith("W")
          ? chalk.yellow("warning")
          : chalk.red("error");
        console.log(`hint: ${type} in ${filename}`);
        console.log(
          `    ${error.line}:${error.character}: ${error.reason} (${error.code})`
        );
        console.log(
          chalk.gray(
            "    " +
              text.slice(0, error.character) +
              chalk.inverse(text.substr(error.character, 1)) +
              text.slice(error.character + 1)
          )
        );
        problems++;
      }
    }
  }
  if (problems) {
    console.log(`hint: ${chalk.cyan(problems + " problems")} in ${filename}`);
  } else {
    console.log(`hint: ${chalk.green("ok")} for ${filename}`);
  }
}

async function addFile(sourcePath, targetPath) {
  const contents = await fs.readFile(pj(".", sourcePath), { encoding: null });
  static.set(sourcePath, `${targetPath}?static=${hash(contents)}`);
  fs.writeFile(pj(buildDir, targetPath), contents);
}

async function addJS(sourcePath, targetPath) {
  const source = await fs.readFile(pj(".", sourcePath), { encoding: "utf8" });
  static.set(sourcePath, `${targetPath}?static=${hash(source)}`);
  runHint(sourcePath, source);
  fs.writeFile(pj(buildDir, targetPath), source);
}

async function addSass(sourcePath, targetPath) {
  const renderedCSS = sass.renderSync({
    file: pj(".", sourcePath),
    outputStyle: "expanded",
    indentType: "tab",
    indentWidth: 1,
    functions: {
      "static($name)": function (name) {
        if (!(name instanceof sass.types.String)) {
          throw "$name: expected a string";
        }
        const result = static.get(name.getValue());
        if (typeof result === "string") {
          return new sass.types.String(result);
        } else {
          throw new Error(
            "static file '" + name.getValue() + "' does not exist"
          );
        }
      },
    },
  }).css;
  static.set(sourcePath, `${targetPath}?static=${hash(renderedCSS)}`);
  validate(sourcePath, renderedCSS, "css");
  await fs.writeFile(pj(buildDir, targetPath), renderedCSS);
}

async function addPug(sourcePath, targetPath) {
  function getRelative(staticTarget) {
    const pathLayer = (
      path.dirname(targetPath).replace(/\/$/, "").match(/\//g) || []
    ).length;
    const prefix = Array(pathLayer).fill("../").join("");
    const result = prefix + staticTarget.replace(/^\//, "");
    if (result) return result;
    else return "./";
  }
  function getStatic(target) {
    return getRelative(static.get(target));
  }
  function getStaticName(target) {
    return getRelative(static.get(target)).replace(/\?.*$/, "");
  }
  function getLink(target) {
    return getRelative(links.get(target));
  }
  const renderedHTML = pug.compileFile(pj(".", sourcePath), { pretty: true })({
    getStatic,
    getStaticName,
    getLink,
    ...pugLocals,
  });
  let renderedWithoutPHP = renderedHTML.replace(/<\?(?:php|=).*?\?>/gms, "");
  validate(sourcePath, renderedWithoutPHP, "html");
  await fs.writeFile(pj(buildDir, targetPath), renderedHTML);
}

async function addBabel(sourcePath, targetPath) {
  const originalCode = await fs.readFile(pj(".", sourcePath), "utf8");

  const compiled = babel.transformSync(originalCode, {
    sourceMaps: false,
    sourceType: "script",
    presets: [
      [
        "@babel/env",
        {
          targets: {
            ie: 11,
          },
        },
      ],
    ],
    generatorOpts: {
      comments: false,
      minified: false,
      sourceMaps: false,
    },
  });

  const filenameWithQuery = `${targetPath}?static=${hash(compiled.code)}`;

  static.set(sourcePath, filenameWithQuery);

  await Promise.all([
    fs.writeFile(pj(buildDir, targetPath), originalCode),
    fs.writeFile(pj(buildDir, minFilename), compiled.code),
    fs.writeFile(pj(buildDir, mapFilename), JSON.stringify(compiled.map)),
  ]);
}

(async () => {
  // Stage 1: Register
  for (const item of spec) {
    if (item.type === "pug") {
      links.set(item.source, item.target.replace(/index.html$/, ""));
    }
  }

  // Stage 2: Build
  for (const item of spec) {
    if (item.type === "file") {
      await addFile(item.source, item.target);
    } else if (item.type === "js") {
      await addJS(item.source, item.target);
    } else if (item.type === "sass") {
      await addSass(item.source, item.target);
    } else if (item.type === "babel") {
      await addBabel(item.source, item.target);
    } else if (item.type === "pug") {
      await addPug(item.source, item.target);
    } else {
      throw new Error("Unknown item type: " + item.type);
    }
  }

  console.log(chalk.green("All files emitted."));

  await Promise.all(validationQueue).then((v) => {
    console.log(`validation: using host ${chalk.cyan(validationHost)}`);
    v.forEach((cont) => cont());
  });

  console.log(chalk.green("Build complete.") + "\n\n------------\n");
})();