import datetime
from io import BytesIO
import os
import shutil

import numpy as np
from packaging.version import parse as parse_version
import pytest

import matplotlib as mpl
import matplotlib.pyplot as plt
from matplotlib.testing import _has_tex_package, _check_for_pgf
from matplotlib.testing.compare import compare_images, ImageComparisonFailure
from matplotlib.backends.backend_pgf import PdfPages, _tex_escape
from matplotlib.testing.decorators import (
    _image_directories, check_figures_equal, image_comparison)
from matplotlib.testing._markers import (
    needs_ghostscript, needs_pgf_lualatex, needs_pgf_pdflatex,
    needs_pgf_xelatex)


baseline_dir, result_dir = _image_directories(lambda: 'dummy func')


def compare_figure(fname, savefig_kwargs={}, tol=0):
    actual = os.path.join(result_dir, fname)
    plt.savefig(actual, **savefig_kwargs)

    expected = os.path.join(result_dir, "expected_%s" % fname)
    shutil.copyfile(os.path.join(baseline_dir, fname), expected)
    err = compare_images(expected, actual, tol=tol)
    if err:
        raise ImageComparisonFailure(err)


@pytest.mark.parametrize('plain_text, escaped_text', [
    (r'quad_sum: $\sum x_i^2$', r'quad_sum: \(\displaystyle \sum x_i^2\)'),
    ('% not a comment', r'\% not a comment'),
    ('^not', r'\^not'),
])
def test_tex_escape(plain_text, escaped_text):
    assert _tex_escape(plain_text) == escaped_text


@needs_pgf_xelatex
@pytest.mark.backend('pgf')
def test_tex_special_chars(tmp_path):
    fig = plt.figure()
    fig.text(.5, .5, "_^ $a_b^c$")
    fig.savefig(tmp_path / "test.pdf")  # Should not error.


def create_figure():
    plt.figure()
    x = np.linspace(0, 1, 15)

    # line plot
    plt.plot(x, x ** 2, "b-")

    # marker
    plt.plot(x, 1 - x**2, "g>")

    # filled paths and patterns
    plt.fill_between([0., .4], [.4, 0.], hatch='//', facecolor="lightgray",
                     edgecolor="red")
    plt.fill([3, 3, .8, .8, 3], [2, -2, -2, 0, 2], "b")

    # text and typesetting
    plt.plot([0.9], [0.5], "ro", markersize=3)
    plt.text(0.9, 0.5, 'unicode (ü, °, µ) and math ($\\mu_i = x_i^2$)',
             ha='right', fontsize=20)
    plt.ylabel('sans-serif, blue, $\\frac{\\sqrt{x}}{y^2}$..',
               family='sans-serif', color='blue')

    plt.xlim(0, 1)
    plt.ylim(0, 1)


# test compiling a figure to pdf with xelatex
@needs_pgf_xelatex
@pytest.mark.backend('pgf')
@image_comparison(['pgf_xelatex.pdf'], style='default')
def test_xelatex():
    rc_xelatex = {'font.family': 'serif',
                  'pgf.rcfonts': False}
    mpl.rcParams.update(rc_xelatex)
    create_figure()


try:
    _old_gs_version = \
        mpl._get_executable_info('gs').version < parse_version('9.50')
except mpl.ExecutableNotFoundError:
    _old_gs_version = True


# test compiling a figure to pdf with pdflatex
@needs_pgf_pdflatex
@pytest.mark.skipif(not _has_tex_package('ucs'), reason='needs ucs.sty')
@pytest.mark.backend('pgf')
@image_comparison(['pgf_pdflatex.pdf'], style='default',
                  tol=11.7 if _old_gs_version else 0)
def test_pdflatex():
    if os.environ.get('APPVEYOR'):
        pytest.xfail("pdflatex test does not work on appveyor due to missing "
                     "LaTeX fonts")

    rc_pdflatex = {'font.family': 'serif',
                   'pgf.rcfonts': False,
                   'pgf.texsystem': 'pdflatex',
                   'pgf.preamble': ('\\usepackage[utf8x]{inputenc}'
                                    '\\usepackage[T1]{fontenc}')}
    mpl.rcParams.update(rc_pdflatex)
    create_figure()


# test updating the rc parameters for each figure
@needs_pgf_xelatex
@needs_pgf_pdflatex
@mpl.style.context('default')
@pytest.mark.backend('pgf')
def test_rcupdate():
    rc_sets = [{'font.family': 'sans-serif',
                'font.size': 30,
                'figure.subplot.left': .2,
                'lines.markersize': 10,
                'pgf.rcfonts': False,
                'pgf.texsystem': 'xelatex'},
               {'font.family': 'monospace',
                'font.size': 10,
                'figure.subplot.left': .1,
                'lines.markersize': 20,
                'pgf.rcfonts': False,
                'pgf.texsystem': 'pdflatex',
                'pgf.preamble': ('\\usepackage[utf8x]{inputenc}'
                                 '\\usepackage[T1]{fontenc}'
                                 '\\usepackage{sfmath}')}]
    tol = [0, 13.2] if _old_gs_version else [0, 0]
    for i, rc_set in enumerate(rc_sets):
        with mpl.rc_context(rc_set):
            for substring, pkg in [('sfmath', 'sfmath'), ('utf8x', 'ucs')]:
                if (substring in mpl.rcParams['pgf.preamble']
                        and not _has_tex_package(pkg)):
                    pytest.skip(f'needs {pkg}.sty')
            create_figure()
            compare_figure(f'pgf_rcupdate{i + 1}.pdf', tol=tol[i])


# test backend-side clipping, since large numbers are not supported by TeX
@needs_pgf_xelatex
@mpl.style.context('default')
@pytest.mark.backend('pgf')
def test_pathclip():
    np.random.seed(19680801)
    mpl.rcParams.update({'font.family': 'serif', 'pgf.rcfonts': False})
    fig, axs = plt.subplots(1, 2)

    axs[0].plot([0., 1e100], [0., 1e100])
    axs[0].set_xlim(0, 1)
    axs[0].set_ylim(0, 1)

    axs[1].scatter([0, 1], [1, 1])
    axs[1].hist(np.random.normal(size=1000), bins=20, range=[-10, 10])
    axs[1].set_xscale('log')

    fig.savefig(BytesIO(), format="pdf")  # No image comparison.


# test mixed mode rendering
@needs_pgf_xelatex
@pytest.mark.backend('pgf')
@image_comparison(['pgf_mixedmode.pdf'], style='default')
def test_mixedmode():
    mpl.rcParams.update({'font.family': 'serif', 'pgf.rcfonts': False})
    Y, X = np.ogrid[-1:1:40j, -1:1:40j]
    plt.pcolor(X**2 + Y**2).set_rasterized(True)


# test bbox_inches clipping
@needs_pgf_xelatex
@mpl.style.context('default')
@pytest.mark.backend('pgf')
def test_bbox_inches():
    mpl.rcParams.update({'font.family': 'serif', 'pgf.rcfonts': False})
    fig, (ax1, ax2) = plt.subplots(1, 2)
    ax1.plot(range(5))
    ax2.plot(range(5))
    plt.tight_layout()
    bbox = ax1.get_window_extent().transformed(fig.dpi_scale_trans.inverted())
    compare_figure('pgf_bbox_inches.pdf', savefig_kwargs={'bbox_inches': bbox},
                   tol=0)


@mpl.style.context('default')
@pytest.mark.backend('pgf')
@pytest.mark.parametrize('system', [
    pytest.param('lualatex', marks=[needs_pgf_lualatex]),
    pytest.param('pdflatex', marks=[needs_pgf_pdflatex]),
    pytest.param('xelatex', marks=[needs_pgf_xelatex]),
])
def test_pdf_pages(system):
    rc_pdflatex = {
        'font.family': 'serif',
        'pgf.rcfonts': False,
        'pgf.texsystem': system,
    }
    mpl.rcParams.update(rc_pdflatex)

    fig1, ax1 = plt.subplots()
    ax1.plot(range(5))
    fig1.tight_layout()

    fig2, ax2 = plt.subplots(figsize=(3, 2))
    ax2.plot(range(5))
    fig2.tight_layout()

    path = os.path.join(result_dir, f'pdfpages_{system}.pdf')
    md = {
        'Author': 'me',
        'Title': 'Multipage PDF with pgf',
        'Subject': 'Test page',
        'Keywords': 'test,pdf,multipage',
        'ModDate': datetime.datetime(
            1968, 8, 1, tzinfo=datetime.timezone(datetime.timedelta(0))),
        'Trapped': 'Unknown'
    }

    with PdfPages(path, metadata=md) as pdf:
        pdf.savefig(fig1)
        pdf.savefig(fig2)
        pdf.savefig(fig1)

        assert pdf.get_pagecount() == 3


@mpl.style.context('default')
@pytest.mark.backend('pgf')
@pytest.mark.parametrize('system', [
    pytest.param('lualatex', marks=[needs_pgf_lualatex]),
    pytest.param('pdflatex', marks=[needs_pgf_pdflatex]),
    pytest.param('xelatex', marks=[needs_pgf_xelatex]),
])
def test_pdf_pages_metadata_check(monkeypatch, system):
    # Basically the same as test_pdf_pages, but we keep it separate to leave
    # pikepdf as an optional dependency.
    pikepdf = pytest.importorskip('pikepdf')
    monkeypatch.setenv('SOURCE_DATE_EPOCH', '0')

    mpl.rcParams.update({'pgf.texsystem': system})

    fig, ax = plt.subplots()
    ax.plot(range(5))

    md = {
        'Author': 'me',
        'Title': 'Multipage PDF with pgf',
        'Subject': 'Test page',
        'Keywords': 'test,pdf,multipage',
        'ModDate': datetime.datetime(
            1968, 8, 1, tzinfo=datetime.timezone(datetime.timedelta(0))),
        'Trapped': 'True'
    }
    path = os.path.join(result_dir, f'pdfpages_meta_check_{system}.pdf')
    with PdfPages(path, metadata=md) as pdf:
        pdf.savefig(fig)

    with pikepdf.Pdf.open(path) as pdf:
        info = {k: str(v) for k, v in pdf.docinfo.items()}

    # Not set by us, so don't bother checking.
    if '/PTEX.FullBanner' in info:
        del info['/PTEX.FullBanner']
    if '/PTEX.Fullbanner' in info:
        del info['/PTEX.Fullbanner']

    # Some LaTeX engines ignore this setting, and state themselves as producer.
    producer = info.pop('/Producer')
    assert producer == f'Matplotlib pgf backend v{mpl.__version__}' or (
            system == 'lualatex' and 'LuaTeX' in producer)

    assert info == {
        '/Author': 'me',
        '/CreationDate': 'D:19700101000000Z',
        '/Creator': f'Matplotlib v{mpl.__version__}, https://matplotlib.org',
        '/Keywords': 'test,pdf,multipage',
        '/ModDate': 'D:19680801000000Z',
        '/Subject': 'Test page',
        '/Title': 'Multipage PDF with pgf',
        '/Trapped': '/True',
    }


@needs_pgf_xelatex
def test_tex_restart_after_error():
    fig = plt.figure()
    fig.suptitle(r"\oops")
    with pytest.raises(ValueError):
        fig.savefig(BytesIO(), format="pgf")

    fig = plt.figure()  # start from scratch
    fig.suptitle(r"this is ok")
    fig.savefig(BytesIO(), format="pgf")


@needs_pgf_xelatex
def test_bbox_inches_tight():
    fig, ax = plt.subplots()
    ax.imshow([[0, 1], [2, 3]])
    fig.savefig(BytesIO(), format="pdf", backend="pgf", bbox_inches="tight")


@needs_pgf_xelatex
@needs_ghostscript
def test_png_transparency():  # Actually, also just testing that png works.
    buf = BytesIO()
    plt.figure().savefig(buf, format="png", backend="pgf", transparent=True)
    buf.seek(0)
    t = plt.imread(buf)
    assert (t[..., 3] == 0).all()  # fully transparent.


@needs_pgf_xelatex
def test_unknown_font(caplog):
    with caplog.at_level("WARNING"):
        mpl.rcParams["font.family"] = "this-font-does-not-exist"
        plt.figtext(.5, .5, "hello, world")
        plt.savefig(BytesIO(), format="pgf")
    assert "Ignoring unknown font: this-font-does-not-exist" in [
        r.getMessage() for r in caplog.records]


@check_figures_equal(extensions=["pdf"])
@pytest.mark.parametrize("texsystem", ("pdflatex", "xelatex", "lualatex"))
@pytest.mark.backend("pgf")
def test_minus_signs_with_tex(fig_test, fig_ref, texsystem):
    if not _check_for_pgf(texsystem):
        pytest.skip(texsystem + ' + pgf is required')
    mpl.rcParams["pgf.texsystem"] = texsystem
    fig_test.text(.5, .5, "$-1$")
    fig_ref.text(.5, .5, "$\N{MINUS SIGN}1$")


@pytest.mark.backend("pgf")
def test_sketch_params():
    fig, ax = plt.subplots(figsize=(3, 3))
    ax.set_xticks([])
    ax.set_yticks([])
    ax.set_frame_on(False)
    handle, = ax.plot([0, 1])
    handle.set_sketch_params(scale=5, length=30, randomness=42)

    with BytesIO() as fd:
        fig.savefig(fd, format='pgf')
        buf = fd.getvalue().decode()

    baseline = r"""\pgfpathmoveto{\pgfqpoint{0.375000in}{0.300000in}}%
\pgfpathlineto{\pgfqpoint{2.700000in}{2.700000in}}%
\usepgfmodule{decorations}%
\usepgflibrary{decorations.pathmorphing}%
\pgfkeys{/pgf/decoration/.cd, """ \
    r"""segment length = 0.150000in, amplitude = 0.100000in}%
\pgfmathsetseed{42}%
\pgfdecoratecurrentpath{random steps}%
\pgfusepath{stroke}%"""
    # \pgfdecoratecurrentpath must be after the path definition and before the
    # path is used (\pgfusepath)
    assert baseline in buf
