import { parseHeader, stringifyHeader, validateHeader } from './header.ts';
import type { BasicCommit, Commit, Header, Options, Result } from './types.ts';
import { isValidString } from './utils.ts';

/**
 * Receives a full commit message `string` and parses it into an `Commit` object
 * and returns it.
 * Basically the same as [.parse](#parse), except that
 * it only can accept single string.
 *
 * _The `parse*` methods are not doing any checking and validation,
 * so you may want to pass the result to `validateCommit` or `checkCommit`,
 * or to `validateCommit` with `ret` option set to `true`._
 *
 * @example
 * import { parseCommit } from 'parse-commit-message';
 *
 * const commitObj = parseCommit('foo: bar qux\n\nokey dude');
 * console.log(commitObj);
 * // => {
 * //   header: { type: 'foo', scope: null, subject: 'bar qux' },
 * //   body: 'okey dude',
 * //   footer: null,
 * // }
 *
 * @name  .parseCommit
 * @param {string} commit a message like `'fix(foo): bar baz\n\nSome awesome body!'`
 * @param {object} options options to control the header regex and case sensitivity
 * @param {RegExp|string} options.headerRegex string regular expression or instance of RegExp
 * @param {boolean} options.caseSensitive whether or not to be case sensitive, defaults to `false`
 * @returns {Commit} a standard object like `{ header: Header, body?, footer? }`
 * @public
 */
export function parseCommit(commit: string, options?: Options): Commit {
  if (!isValidString(commit)) {
    throw new TypeError(`expect \`commit\` to be non empty string`);
  }

  const header = parseHeader(commit, options);
  const [body = null, footer = null] = commit.split('\n\n').slice(1);

  return { header, body, footer };
}

/**
 * Receives a `Commit` object, validates it using `validateCommit`,
 * builds a "commit" string and returns it. Method throws if problems found.
 * Basically the same as [.stringify](#stringify), except that
 * it only can accept single `Commit` object.
 *
 * @example
 * import { stringifyCommit } from 'parse-commit-message';
 *
 * const commitStr = stringifyCommit({
 *   header: { type: 'foo', subject: 'bar qux' },
 *   body: 'okey dude',
 * });
 * console.log(commitStr); // => 'foo: bar qux\n\nokey dude'
 *
 * @name  .stringifyCommit
 * @param {Commit} commit a `Commit` object like `{ header: Header, body?, footer? }`
 * @param {object} options options to control the header regex and case sensitivity
 * @param {RegExp|string} options.headerRegex string regular expression or instance of RegExp
 * @param {boolean} options.caseSensitive whether or not to be case sensitive, defaults to `false`
 * @returns {string} a commit nessage stirng like `'fix(foo): bar baz'`
 * @public
 */
export function stringifyCommit(commit: Commit | BasicCommit, options?: Options): string {
  const result = validateCommit(commit, options);

  if (result.error || !result.value) {
    const err = result.error || new TypeError('expect `commit` to be a valid object');
    throw err;
  }

  const header = stringifyHeader(result.value.header, options);
  const EOL = '\n';

  result.value.body = result.value.body ? EOL + EOL + result.value.body : '';
  result.value.footer = result.value.footer ? EOL + EOL + result.value.footer : '';

  return `${header}${result.value.body}${result.value.footer}`;
}

/**
 * Validates given `Commit` object and returns `Result`.
 * Basically the same as [.validate](#validate), except that
 * it only can accept single `Commit` object.
 *
 * @example
 * import { validateCommit } from 'parse-commit-message';
 *
 * const commit = {
 *   header: { type: 'foo', subject: 'bar qux' },
 *   body: 'okey dude',
 * };
 *
 * const commitIsValid = validateCommit(commit);
 * console.log(commitIsValid); // => true
 *
 * const { value } = validateCommit(commit, true);
 * console.log(value);
 * // => {
 * //   header: { type: 'foo', scope: null, subject: 'bar qux' },
 * //   body: 'okey dude',
 * //   footer: null,
 * // }
 *
 * @name  .validateCommit
 * @param {Commit|BasicCommit} commit a `Commit` like `{ header: Header, body?, footer? }`
 * @param {object} options options to control the header regex and case sensitivity
 * @param {RegExp|string} options.headerRegex string regular expression or instance of RegExp
 * @param {boolean} options.caseSensitive whether or not to be case sensitive, defaults to `false`
 * @returns {Result} an object like `{ value: Array<Commit>, error: Error }`
 * @public
 */
export function validateCommit(
  commit: Commit | BasicCommit,
  options?: Options,
): Result<Commit | BasicCommit> {
  const result = {} as Result<Commit | BasicCommit>;

  try {
    result.value = checkCommit(commit, options) as Commit | BasicCommit;
  } catch (err) {
    return { error: err } as Result<any>;
  }

  return result as Result<Commit | BasicCommit>;
}

/**
 * Receives a `Commit` and checks if it is valid. Method throws if problems found.
 * Basically the same as [.check](#check), except that
 * it only can accept single `Commit` object.
 *
 * @example
 * import { checkCommit } from 'parse-commit-message';
 *
 * try {
 *   checkCommit({ header: { type: 'fix' } });
 * } catch(err) {
 *   console.log(err);
 *   // => TypeError: header.subject should be non empty string
 * }
 *
 * // throws because can accept only Commit objects
 * checkCommit('foo bar baz');
 * checkCommit(123);
 * checkCommit([{ header: { type: 'foo', subject: 'bar' } }]);
 *
 * @name  .checkCommit
 * @param {Commit} commit a `Commit` like `{ header: Header, body?, footer? }`
 * @param {object} options options to control the header regex and case sensitivity
 * @param {RegExp|string} options.headerRegex string regular expression or instance of RegExp
 * @param {boolean} options.caseSensitive whether or not to be case sensitive, defaults to `false`
 * @returns {Commit} returns the same as given if no problems, otherwise it will throw.
 * @public
 */
export function checkCommit(commit: Commit | BasicCommit, options?: Options): Commit {
  const { error, value: headerObj } = validateHeader(commit.header, options) as {
    error?: Error;
    value: Header;
  };
  if (error) {
    throw error;
  }

  const isValidBody =
    'body' in commit && commit.body !== null ? typeof commit.body === 'string' : true;

  if (!isValidBody) {
    throw new TypeError('commit.body should be string when given');
  }

  const isValid =
    'footer' in commit && commit.footer !== null ? typeof commit.footer === 'string' : true;

  if (!isValid) {
    throw new TypeError('commit.footer should be string when given');
  }

  return { body: null, footer: null, ...commit, header: headerObj };
}