sebmck/6to5

// @flow

import browserslist from "browserslist";
import findSuggestion from "levenary";
import invariant from "invariant";
import browserModulesData from "@babel/compat-data/native-modules";

import {
  semverify,
  semverMin,
  isUnreleasedVersion,
  getLowestUnreleased,
} from "./utils";
import { browserNameMap } from "./targets";
import { TargetNames } from "./options";
import type { Target, Targets, InputTargets, Browsers } from "./types";

export type { Targets, InputTargets };

export { prettifyTargets } from "./pretty";
export { getInclusionReasons } from "./debug";
export { default as filterItems, isRequired } from "./filter-items";
export { unreleasedLabels } from "./targets";

const browserslistDefaults = browserslist.defaults;

const validBrowserslistTargets = [
  ...Object.keys(browserslist.data),
  ...Object.keys(browserslist.aliases),
];

function objectToBrowserslist(object: Targets): Array<string> {
  return Object.keys(object).reduce((list, targetName) => {
    if (validBrowserslistTargets.indexOf(targetName) >= 0) {
      const targetVersion = object[targetName];
      return list.concat(`${targetName} ${targetVersion}`);
    }
    return list;
  }, []);
}

function validateTargetNames(targets: InputTargets): Targets {
  const validTargets = Object.keys(TargetNames);
  for (const target in targets) {
    if (!TargetNames[target]) {
      throw new Error(
        `Invalid Option: '${target}' is not a valid target
        Maybe you meant to use '${findSuggestion(target, validTargets)}'?`,
      );
    }
  }

  // $FlowIgnore
  return targets;
}

export function isBrowsersQueryValid(browsers: Browsers | Targets): boolean {
  return typeof browsers === "string" || Array.isArray(browsers);
}

function validateBrowsers(browsers: Browsers | void) {
  invariant(
    typeof browsers === "undefined" || isBrowsersQueryValid(browsers),
    `Invalid Option: '${String(browsers)}' is not a valid browserslist query`,
  );

  return browsers;
}

function getLowestVersions(browsers: Array<string>): Targets {
  return browsers.reduce((all: Object, browser: string): Object => {
    const [browserName, browserVersion] = browser.split(" ");
    const normalizedBrowserName = browserNameMap[browserName];

    if (!normalizedBrowserName) {
      return all;
    }

    try {
      // Browser version can return as "10.0-10.2"
      const splitVersion = browserVersion.split("-")[0].toLowerCase();
      const isSplitUnreleased = isUnreleasedVersion(splitVersion, browserName);

      if (!all[normalizedBrowserName]) {
        all[normalizedBrowserName] = isSplitUnreleased
          ? splitVersion
          : semverify(splitVersion);
        return all;
      }

      const version = all[normalizedBrowserName];
      const isUnreleased = isUnreleasedVersion(version, browserName);

      if (isUnreleased && isSplitUnreleased) {
        all[normalizedBrowserName] = getLowestUnreleased(
          version,
          splitVersion,
          browserName,
        );
      } else if (isUnreleased) {
        all[normalizedBrowserName] = semverify(splitVersion);
      } else if (!isUnreleased && !isSplitUnreleased) {
        const parsedBrowserVersion = semverify(splitVersion);

        all[normalizedBrowserName] = semverMin(version, parsedBrowserVersion);
      }
    } catch (e) {}

    return all;
  }, {});
}

function outputDecimalWarning(decimalTargets: Array<Object>): void {
  if (!decimalTargets?.length) {
    return;
  }

  console.log("Warning, the following targets are using a decimal version:");
  console.log("");
  decimalTargets.forEach(({ target, value }) =>
    console.log(`  ${target}: ${value}`),
  );
  console.log("");
  console.log(
    "We recommend using a string for minor/patch versions to avoid numbers like 6.10",
  );
  console.log("getting parsed as 6.1, which can lead to unexpected behavior.");
  console.log("");
}

function semverifyTarget(target, value) {
  try {
    return semverify(value);
  } catch (error) {
    throw new Error(
      `Invalid Option: '${value}' is not a valid value for 'targets.${target}'.`,
    );
  }
}

const targetParserMap = {
  __default(target, value) {
    const version = isUnreleasedVersion(value, target)
      ? value.toLowerCase()
      : semverifyTarget(target, value);
    return [target, version];
  },

  // Parse `node: true` and `node: "current"` to version
  node(target, value) {
    const parsed =
      value === true || value === "current"
        ? process.versions.node
        : semverifyTarget(target, value);
    return [target, parsed];
  },
};

type ParsedResult = {
  targets: Targets,
  decimalWarnings: Array<Object>,
};

export default function getTargets(
  inputTargets: InputTargets = {},
  options: Object = {},
): Targets {
  const targetOpts: Targets = {};
  let { browsers } = inputTargets;

  // `esmodules` as a target indicates the specific set of browsers supporting ES Modules.
  // These values OVERRIDE the `browsers` field.
  if (inputTargets.esmodules) {
    const supportsESModules = browserModulesData["es6.module"];
    browsers = Object.keys(supportsESModules)
      .map(browser => `${browser} ${supportsESModules[browser]}`)
      .join(", ");
  }

  // Parse browsers target via browserslist
  const browsersquery = validateBrowsers(browsers);

  // Remove esmodules after being consumed to fix `hasTargets` below
  const input = { ...inputTargets };
  delete input.esmodules;
  delete input.browsers;

  let targets: Targets = validateTargetNames(input);

  const shouldParseBrowsers = !!browsersquery;
  const hasTargets = shouldParseBrowsers || Object.keys(targets).length > 0;
  const shouldSearchForConfig =
    !options.ignoreBrowserslistConfig && !hasTargets;

  if (shouldParseBrowsers || shouldSearchForConfig) {
    // If no targets are passed, we need to overwrite browserslist's defaults
    // so that we enable all transforms (acting like the now deprecated
    // preset-latest).
    //
    // Note, if browserslist resolves the config (ex. package.json), then usage
    // of `defaults` in queries will be different since we don't want to break
    // the behavior of "no targets is the same as preset-latest".
    if (!hasTargets) {
      browserslist.defaults = objectToBrowserslist(targets);
    }

    const browsers = browserslist(browsersquery, {
      path: options.configPath,
      mobileToDesktop: true,
      env: options.browserslistEnv,
    });

    const queryBrowsers = getLowestVersions(browsers);
    targets = Object.assign(queryBrowsers, targets);

    // Reset browserslist defaults
    browserslist.defaults = browserslistDefaults;
  }

  // Parse remaining targets
  const parsed = (Object.keys(targets): Array<Target>).sort().reduce(
    (results: ParsedResult, target: $Keys<Targets>): ParsedResult => {
      const value = targets[target];

      // Warn when specifying minor/patch as a decimal
      if (typeof value === "number" && value % 1 !== 0) {
        results.decimalWarnings.push({ target, value });
      }

      // Check if we have a target parser?
      // $FlowIgnore - Flow doesn't like that some targetParserMap[target] might be missing
      const parser = targetParserMap[target] ?? targetParserMap.__default;
      const [parsedTarget, parsedValue] = parser(target, value);

      if (parsedValue) {
        // Merge (lowest wins)
        results.targets[parsedTarget] = parsedValue;
      }

      return results;
    },
    {
      targets: targetOpts,
      decimalWarnings: [],
    },
  );

  outputDecimalWarning(parsed.decimalWarnings);

  return parsed.targets;
}