#!/usr/bin/env python

from __future__ import print_function

import argparse
import os
import subprocess
import sys

from test_util import TestFailedError, prepareForIncrParse, run_command


def main():
    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description='Utility for testing incremental syntax parsing',
        epilog='''
    Based of a single template the utility generates a pre-edit and a post-edit
    file. It then verifies that incrementally parsing the post-edit file base
    on the pre-edit file results in the same syntax tree as reparsing the
    post-edit file from scratch.

    To generate the pre-edit and the post-edit file from the template, it
    operates on markers of the form:

        <<test_case<pre|||post>>>

    These placeholders are replaced by:
      - 'pre' if a different test case than 'test_case' is run
      - 'pre' for the pre-edit version of 'test_case'
      - 'post' for the post-edit version of 'test_case'
    ''')
    parser.add_argument(
        'file', type=argparse.FileType(),
        help='The template file to test')
    parser.add_argument(
        '--test-case', default='',
        help='The test case to execute. If no test case is specified all \
              unnamed substitutions are applied')
    parser.add_argument(
        '--temp-dir', required=True,
        help='A temporary directory where pre-edit and post-edit files can be \
              saved')
    parser.add_argument(
        '--swiftsyntax-lit-test-helper', required=True,
        help='The path to the lit-test-helper binary of SwiftSyntax')

    args = parser.parse_args(sys.argv[1:])

    test_file = args.file.name
    test_file_name = os.path.basename(test_file)
    test_case = args.test_case
    temp_dir = args.temp_dir
    swiftsyntax_lit_test_helper = args.swiftsyntax_lit_test_helper

    if not os.path.exists(temp_dir):
        os.makedirs(temp_dir)

    pre_edit_file = temp_dir + '/' + test_file_name + '.' + test_case + \
        '.pre.swift'
    post_edit_file = temp_dir + '/' + test_file_name + '.' + test_case + \
        '.post.swift'
    after_roundtrip_file = temp_dir + '/' + test_file_name + '.' \
        + test_case + '.post_after_roundtrip.swift'

    # =========================================================================
    # First generate the pre-edit and post-edit Swift file and gather the edits
    # and expected reparse regions. This is the parser for the special edit
    # markup for testing incremental parsing
    # =========================================================================

    # Gather command line arguments for swift-syntax-test specifiying the
    # performed edits in this list
    incremental_edit_args = []
    reparse_args = []
    try:
        prepareForIncrParse(test_file=test_file, test_case=test_case,
                            pre_edit_file=pre_edit_file,
                            post_edit_file=post_edit_file,
                            incremental_edit_args=incremental_edit_args,
                            reparse_args=reparse_args)
    except TestFailedError as e:
        print('Test case "%s" of %s FAILed' % (test_case, test_file),
              file=sys.stderr)
        print(e.message, file=sys.stderr)
        sys.exit(1)

    try:
        run_command([swiftsyntax_lit_test_helper, '-parse-incremental'] +
                    ['-old-source-file', pre_edit_file] +
                    ['-source-file', post_edit_file] +
                    incremental_edit_args + reparse_args +
                    ['-out', after_roundtrip_file])
    except subprocess.CalledProcessError as e:
        print('Test case "%s" of %s FAILed' % (test_case, test_file),
              file=sys.stderr)
        print('Parsing the swift file failed:\n', file=sys.stderr)
        print(e.output, file=sys.stderr)
        sys.exit(1)

    # Check if the two syntax trees are the same
    try:
        run_command(
            [
                'diff', '-u',
                post_edit_file,
                after_roundtrip_file
            ])
    except subprocess.CalledProcessError as e:
        print('Test case "%s" of %s FAILed' % (test_case, test_file),
              file=sys.stderr)
        print('Source file after incrementally parsing '
              'does not match post-edit source file:\n\n',
              file=sys.stderr)
        print(e.output, file=sys.stderr)
        sys.exit(1)


if __name__ == '__main__':
    main()