"""test_pdfforms_writer.py - Unit tests for PDF writer"""
# Copyright © 2020  Brett Smith
# License: AGPLv3-or-later WITH Beancount-Plugin-Additional-Permission-1.0
#
# Full copyright and licensing details can be found at toplevel file
# LICENSE.txt in the repository.

import codecs
import io
import logging
import re
import shutil

from pathlib import Path

import pytest
import yaml

from . import testutil
from pdfminer.pdfdocument import PDFDocument
from pdfminer.pdfparser import PDFParser
from pdfminer.pdftypes import resolve1
from pdfminer.psparser import PSLiteral

from conservancy_beancount.pdfforms import fill as fillmod

PDFTK = shutil.which('pdftk')
# Per the PDF spec, 7.2.2 "Character Set" Table 1
WHITESPACE = b'\x00\x09\x0A\x0C\x0D\x20'
WHITESPACE_RE = re.compile(b'[' + WHITESPACE + b']+')

@pytest.fixture(scope='module')
def writer():
    return fillmod.PDFWriter()

def expected_re(expected):
    pattern = re.escape(expected)
    # Unescape some things that don't strictly need to be escaped.
    pattern = re.sub(rb'\\(<|>| )', rb'\1', pattern)
    # Allow arbitrary whitespace around punctuation tokens.
    pattern = re.sub(rb'(<<|>>|\\\[|\\\])', rb'\\s*\1\\s*', pattern)
    # Allow any kind of whitespace where any is required.
    pattern = WHITESPACE_RE.sub(rb'\\s+', pattern)
    return pattern

def utf16_str(s):
    return b''.join([
        b'(',
        codecs.BOM_UTF16_BE,
        s.encode('utf-16be'),
        b')',
    ])

def open_pdf(source):
    if isinstance(source, Path):
        source = source.open('rb')
    else:
        source.seek(0)
    return PDFDocument(PDFParser(source))

def merge_form(yaml_fills, form_filename='form1.fdf', form_key='FDF'):
    with testutil.test_path(f'pdfforms/{form_filename}') as fdf_path:
        pdf = open_pdf(fdf_path)
        pdf_fields = resolve1(pdf.catalog[form_key])['Fields']
        return fillmod.merge_form(yaml_fills, pdf_fields)

@pytest.mark.parametrize('source,expected', [
    (None, b'null'),
    (True, b'true'),
    (False, b'false'),
    (0, b'0'),
    (1, b'1'),
    (345, b'345'),
    (34.56, b'34.56'),
    ('', b'()'),
    ('ascii', b'(ascii)'),
    (')parens(', br'(\)parens\()'),
    ('UTF—16', utf16_str('UTF—16')),
    (')¤(', utf16_str(r'\)¤\(')),
    (PSLiteral('lit'), b'/lit'),
    (PSLiteral('# header'), b'/#23#20header'),
])
def test_write_scalar(writer, source, expected):
    actual = b''.join(writer.emit(source)).strip(WHITESPACE)
    assert actual == expected

@pytest.mark.parametrize('source,expected', [
    ([], b'[]'),
    ([1, 2, 3], b'[1 2 3]'),
    ([[1, 3], [2, 4], []], b'[[1 3][2 4][]]'),
    ({}, b'<<>>'),
    ({'Yes': True, 'No': False}, b'<</Yes true /No false>>'),
    ({'Kids': [1, 2, 3]}, b'<</Kids [1 2 3]>>'),
])
def test_write_compound(writer, source, expected):
    pattern = expected_re(expected)
    actual = b''.join(writer.emit(source))
    assert re.fullmatch(pattern, actual)

def test_write_document(writer):
    pysrc = {'FDF': {'Fields': [
        {'FT': PSLiteral('Tx'), 'T': 'text'},
        {'FT': PSLiteral('Btn'), 'T': 'check'},
    ]}}
    doc = io.BytesIO()
    writer.write_document(pysrc, doc)
    pdf = open_pdf(doc)
    assert len(pdf.catalog) == 1
    actual = resolve1(pdf.catalog['FDF'])
    assert len(actual) == 1
    f1, f2 = actual['Fields']
    assert f1['FT'].name == 'Tx'
    assert f1['T'] == b'text'
    assert f2['FT'].name == 'Btn'
    assert f2['T'] == b'check'

def test_merge():
    with testutil.test_path('pdfforms/form1_fill.yml').open() as yaml_file:
        form_yaml = yaml.safe_load(yaml_file)['fields']
    actual, errors = merge_form(form_yaml)
    assert not errors
    expected = {
        'text1_0': 'text 1.0',
        'button1_0': PSLiteral('1'),
        'button1_1': None,
        'text1_1': 'text 1.1',
        'text2_0': 'text 2.0',
        'button2_0': None,
        'button2_1': PSLiteral('2'),
    }
    for field in actual:
        try:
            expect_value = expected.pop(field['T'])
        except KeyError:
            pass
        else:
            actual_value = field.get('V')
            if isinstance(expect_value, PSLiteral):
                assert actual_value.name == expect_value.name
            else:
                assert actual_value == expect_value
        actual.extend(field.get('Kids', ()))
    assert not expected, "not all expected fields found in filled form data"

@pytest.mark.parametrize('name', [None, 'nonesuchfield'])
def test_merge_bad_name(name):
    fill = {'fdf': {}}
    if name is not None:
        fill['fdf']['name'] = name
    _, errors = merge_form([fill])
    error, = errors
    assert error.level >= logging.ERROR
    assert error.yaml_index == 0
    assert error.name == name

@pytest.mark.parametrize('name,yaml_type', [
    ('topform.text1_0', 'Btn'),
    ('topform.button1.button1_0', 'Tx'),
])
def test_merge_yaml_wrong_type(name, yaml_type):
    fill = {'fdf': {'name': name, 'type': yaml_type}}
    _, errors = merge_form([fill])
    error, = errors
    assert error.level >= logging.WARNING
    assert error.yaml_index == 0
    assert error.name == name

@pytest.mark.parametrize('value', ['', ' ', 'readwrite'])
def test_merge_readonly_field(value):
    fill = [{
        'fdf': {'name': 'topform.text2_R'},
        'value': value,
    }]
    _, errors = merge_form(fill)
    error, = errors
    assert error.level >= logging.WARNING
    assert error.yaml_index == 0
    assert error.name == 'topform.text2_R'

@pytest.mark.parametrize('value', [None, True, 'Yes'])
def test_merge_nonterminal_field(value):
    yaml_fills = [{
        'fdf': {'name': 'topform.button1'},
        'value': value,
    }]
    _, errors = merge_form(yaml_fills)
    if value is None:
        assert not errors
    else:
        error, = errors
        assert error.level >= logging.WARNING
        assert error.yaml_index == 0
        assert error.name == 'topform.button1'

@pytest.mark.parametrize('value', [None, True, 'Yes'])
def test_merge_unsupported_field_type(value):
    yaml_fills = [{
        'fdf': {'name': 'topform.submit', 'type': 'Btn'},
        'value': value,
    }]
    _, errors = merge_form(yaml_fills)
    if value is None:
        assert not errors
    else:
        error, = errors
        assert error.level >= logging.WARNING
        assert error.yaml_index == 0
        assert error.name == 'topform.submit'

@pytest.mark.parametrize('value', [True, False, [], {}])
def test_merge_unsupported_text_value(value):
    yaml_fills = [{
        'fdf': {'name': 'topform.text1_0'},
        'value': value,
    }]
    _, errors = merge_form(yaml_fills)
    error, = errors
    assert error.level >= logging.ERROR
    assert error.yaml_index == 0
    assert error.name == 'topform.text1_0'

@pytest.mark.parametrize('value', ['', 'Off', 'Yes', [], {}])
def test_merge_unsupported_checkbox_value(value):
    yaml_fills = [{
        'fdf': {'name': 'topform.button1.button1_0'},
        'value': value,
    }]
    _, errors = merge_form(yaml_fills)
    error, = errors
    assert error.level >= logging.ERROR
    assert error.yaml_index == 0
    assert error.name == 'topform.button1.button1_0'

def test_generate():
    source = [
        {'fdf': {'name': 'form.text', 'type': 'Tx'}, 'value': 'generated'},
        {'fdf': {'name': 'form.button', 'type': 'Btn'}, 'value': True},
    ]
    actual, errors = fillmod.generate_form(source)
    assert not errors
    form_root, = actual
    assert form_root['T'] == 'form'
    assert 'V' not in form_root
    text, checkbox = form_root['Kids']
    assert text['T'] == 'text'
    assert text['V'] == 'generated'
    assert not text.get('Kids')
    assert checkbox['T'] == 'button'
    assert checkbox['V'].name == 'Yes'
    assert not checkbox.get('Kids')

@pytest.mark.parametrize('options,value', [
    (['1'], True),
    (['1'], False),
    (['On', 'Off'], True),
    (['On', 'Off'], False),
])
def test_generate_checkbox_with_options(options, value):
    source = [{
        'fdf': {'name': 'cbox', 'type': 'Btn', 'options': options},
        'value': value,
    }]
    actual, errors = fillmod.generate_form(source)
    assert not errors
    assert actual[0]['V'].name == (options[0] if value else 'Off')

@pytest.mark.parametrize('yaml_type', [None, 'Ch', 'Sig'])
def test_generate_unsupported_field_type(yaml_type):
    source = [{
        'fdf': {'name': 'badtype', 'type': yaml_type},
        'value': 'unsupported type value',
    }]
    if yaml_type is None:
        del source[0]['fdf']['type']
    _, errors = fillmod.generate_form(source)
    error, = errors
    assert error.level >= logging.ERROR
    assert error.yaml_index == 0
    assert error.name == 'badtype'

def test_generate_invalid_field_type():
    source = [{
        'fdf': {'name': 'badtype', 'type': '<unknown>'},
        'value': 'unsupported type value',
    }]
    _, errors = fillmod.generate_form(source)
    assert errors
    found_msg = False
    for error in errors:
        assert error.level >= logging.ERROR
        assert error.yaml_index == 0
        assert error.name == 'badtype'
        found_msg = found_msg or '<unknown>' in error.errdesc
    assert found_msg, "no errors mentioned unknown field type"

@pytest.mark.parametrize('value', [True, False, [], {}])
def test_generate_unsupported_text_value(value):
    source = [{
        'fdf': {'name': 'badtext', 'type': 'Tx'},
        'value': value,
    }]
    _, errors = fillmod.generate_form(source)
    error, = errors
    assert error.level >= logging.ERROR
    assert error.yaml_index == 0
    assert error.name == 'badtext'

@pytest.mark.parametrize('value', ['', 'Off', 'Yes', [], {}])
def test_generate_unsupported_checkbox_value(value):
    source = [{
        'fdf': {'name': 'badbutton', 'type': 'Btn'},
        'value': value,
    }]
    _, errors = fillmod.generate_form(source)
    error, = errors
    assert error.level >= logging.ERROR
    assert error.yaml_index == 0
    assert error.name == 'badbutton'

def test_main_generate_fdf():
    arglist = ['--output-file=-', str(testutil.test_path('pdfforms/form1_fill.yml'))]
    stdout = io.BytesIO()
    stderr = io.StringIO()
    retcode = fillmod.main(arglist, stdout, stderr)
    assert retcode == 0
    assert not stderr.getvalue()
    patterns = iter(expected_re(p) for p in [
            b'/T (text1_0)',
            b'/V (text 1.0)',
            b'/T (button1_0)',
            b'/V /1',
            b'/T (text2_0)',
            b'/V (text 2.0)',
            b'/T (button2_1)',
            b'/V /2',
    ])
    pattern = next(patterns)
    stdout.seek(0)
    for line in stdout:
        if re.search(pattern, line):
            try:
                pattern = next(patterns)
            except StopIteration:
                break
    else:
        pytest.fail(f"pattern {pattern!r} not found in FDF output")

@pytest.mark.skipif(not PDFTK, reason="need pdftk installed")
@pytest.mark.xfail(reason="`pdftk fill_form` expects a full PDF")
def test_main_fill_pdf():
    arglist = [
        '--pdftk', PDFTK,
        '--output-file', '-',
        str(testutil.test_path('pdfforms/form1_fill.yml')),
        str(testutil.test_path('pdfforms/form1.fdf')),
    ]
    stdout = io.BytesIO()
    stderr = io.StringIO()
    retcode = fillmod.main(arglist, stdout, stderr)
    assert retcode == 0
    assert not stderr.getvalue()
    patterns = iter(expected_re(p) for p in [
            b'/T (text1_0)',
            b'/V (text 1.0)',
            b'/T (button1_0)',
            b'/V /1',
            b'/T (text2_0)',
            b'/V (text 2.0)',
            b'/T (button2_1)',
            b'/V /2',
    ])
    pattern = next(patterns)
    stdout.seek(0)
    for line in stdout:
        if re.search(pattern, line):
            try:
                pattern = next(patterns)
            except StopIteration:
                break
    else:
        pytest.fail(f"pattern {pattern!r} not found in FDF output")