import re
from tempfile import TemporaryFile

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

import matplotlib as mpl
from matplotlib import dviread
from matplotlib.testing import _has_tex_package
from matplotlib.testing.decorators import check_figures_equal, image_comparison
from matplotlib.testing._markers import needs_usetex
import matplotlib.pyplot as plt


pytestmark = needs_usetex


@image_comparison(
    baseline_images=['test_usetex'],
    extensions=['pdf', 'png'],
    style="mpl20")
def test_usetex():
    mpl.rcParams['text.usetex'] = True
    fig, ax = plt.subplots()
    kwargs = {"verticalalignment": "baseline", "size": 24,
              "bbox": dict(pad=0, edgecolor="k", facecolor="none")}
    ax.text(0.2, 0.7,
            # the \LaTeX macro exercises character sizing and placement,
            # \left[ ... \right\} draw some variable-height characters,
            # \sqrt and \frac draw horizontal rules, \mathrm changes the font
            r'\LaTeX\ $\left[\int\limits_e^{2e}'
            r'\sqrt\frac{\log^3 x}{x}\,\mathrm{d}x \right\}$',
            **kwargs)
    ax.text(0.2, 0.3, "lg", **kwargs)
    ax.text(0.4, 0.3, r"$\frac{1}{2}\pi$", **kwargs)
    ax.text(0.6, 0.3, "$p^{3^A}$", **kwargs)
    ax.text(0.8, 0.3, "$p_{3_2}$", **kwargs)
    for x in {t.get_position()[0] for t in ax.texts}:
        ax.axvline(x)
    for y in {t.get_position()[1] for t in ax.texts}:
        ax.axhline(y)
    ax.set_axis_off()


@check_figures_equal(extensions=['png', 'pdf', 'svg'])
def test_empty(fig_test, fig_ref):
    mpl.rcParams['text.usetex'] = True
    fig_test.text(.5, .5, "% a comment")


@check_figures_equal(extensions=['png', 'pdf', 'svg'])
def test_unicode_minus(fig_test, fig_ref):
    mpl.rcParams['text.usetex'] = True
    fig_test.text(.5, .5, "$-$")
    fig_ref.text(.5, .5, "\N{MINUS SIGN}")


def test_mathdefault():
    plt.rcParams["axes.formatter.use_mathtext"] = True
    fig = plt.figure()
    fig.add_subplot().set_xlim(-1, 1)
    # Check that \mathdefault commands generated by tickers don't cause
    # problems when later switching usetex on.
    mpl.rcParams['text.usetex'] = True
    fig.canvas.draw()


@image_comparison(['eqnarray.png'])
def test_multiline_eqnarray():
    text = (
        r'\begin{eqnarray*}'
        r'foo\\'
        r'bar\\'
        r'baz\\'
        r'\end{eqnarray*}'
    )

    fig = plt.figure(figsize=(1, 1))
    fig.text(0.5, 0.5, text, usetex=True,
             horizontalalignment='center', verticalalignment='center')


@pytest.mark.parametrize("fontsize", [8, 10, 12])
def test_minus_no_descent(fontsize):
    # Test special-casing of minus descent in DviFont._height_depth_of, by
    # checking that overdrawing a 1 and a -1 results in an overall height
    # equivalent to drawing either of them separately.
    mpl.style.use("mpl20")
    mpl.rcParams['font.size'] = fontsize
    heights = {}
    fig = plt.figure()
    for vals in [(1,), (-1,), (-1, 1)]:
        fig.clear()
        for x in vals:
            fig.text(.5, .5, f"${x}$", usetex=True)
        fig.canvas.draw()
        # The following counts the number of non-fully-blank pixel rows.
        heights[vals] = ((np.array(fig.canvas.buffer_rgba())[..., 0] != 255)
                         .any(axis=1).sum())
    assert len({*heights.values()}) == 1


@pytest.mark.parametrize('pkg', ['xcolor', 'chemformula'])
def test_usetex_packages(pkg):
    if not _has_tex_package(pkg):
        pytest.skip(f'{pkg} is not available')
    mpl.rcParams['text.usetex'] = True

    fig = plt.figure()
    text = fig.text(0.5, 0.5, "Some text 0123456789")
    fig.canvas.draw()

    mpl.rcParams['text.latex.preamble'] = (
        r'\PassOptionsToPackage{dvipsnames}{xcolor}\usepackage{%s}' % pkg)
    fig = plt.figure()
    text2 = fig.text(0.5, 0.5, "Some text 0123456789")
    fig.canvas.draw()
    np.testing.assert_array_equal(text2.get_window_extent(),
                                  text.get_window_extent())


@pytest.mark.parametrize(
    "preamble",
    [r"\usepackage[full]{textcomp}", r"\usepackage{underscore}"],
)
def test_latex_pkg_already_loaded(preamble):
    plt.rcParams["text.latex.preamble"] = preamble
    fig = plt.figure()
    fig.text(.5, .5, "hello, world", usetex=True)
    fig.canvas.draw()


def test_usetex_with_underscore():
    plt.rcParams["text.usetex"] = True
    df = {"a_b": range(5)[::-1], "c": range(5)}
    fig, ax = plt.subplots()
    ax.plot("c", "a_b", data=df)
    ax.legend()
    ax.text(0, 0, "foo_bar", usetex=True)
    plt.draw()


@pytest.mark.flaky(reruns=3)  # Tends to hit a TeX cache lock on AppVeyor.
@pytest.mark.parametrize("fmt", ["pdf", "svg"])
def test_missing_psfont(fmt, monkeypatch):
    """An error is raised if a TeX font lacks a Type-1 equivalent"""
    monkeypatch.setattr(
        dviread.PsfontsMap, '__getitem__',
        lambda self, k: dviread.PsFont(
            texname=b'texfont', psname=b'Some Font',
            effects=None, encoding=None, filename=None))
    mpl.rcParams['text.usetex'] = True
    fig, ax = plt.subplots()
    ax.text(0.5, 0.5, 'hello')
    with TemporaryFile() as tmpfile, pytest.raises(ValueError):
        fig.savefig(tmpfile, format=fmt)


def test_pdf_type1_font_subsetting():
    """Test that fonts in PDF output are properly subset."""
    pikepdf = pytest.importorskip("pikepdf")

    mpl.rcParams["text.usetex"] = True
    mpl.rcParams["text.latex.preamble"] = r"\usepackage{amssymb}"
    fig, ax = plt.subplots()
    ax.text(0.2, 0.7, r"$\int_{-\infty}^{\aleph}\sqrt{\alpha\beta\gamma}\mathrm{d}x$")
    ax.text(0.2, 0.5, r"$\mathfrak{x}\circledcirc\mathfrak{y}\in\mathbb{R}$")

    with TemporaryFile() as tmpfile:
        fig.savefig(tmpfile, format="pdf")
        tmpfile.seek(0)
        pdf = pikepdf.Pdf.open(tmpfile)

        length = {}
        page = pdf.pages[0]
        for font_name, font in page.Resources.Font.items():
            assert font.Subtype == "/Type1", (
                f"Font {font_name}={font} is not a Type 1 font"
            )

            # Subsetted font names have a 6-character tag followed by a '+'
            base_font = str(font["/BaseFont"]).removeprefix("/")
            assert re.match(r"^[A-Z]{6}\+", base_font), (
                f"Font {font_name}={base_font} lacks a subset indicator tag"
            )
            assert "/FontFile" in font.FontDescriptor, (
                f"Type 1 font {font_name}={base_font} is not embedded"
            )
            _, original_name = base_font.split("+", 1)
            length[original_name] = len(bytes(font["/FontDescriptor"]["/FontFile"]))

    print("Embedded font stream lengths:", length)
    # We should have several fonts, each much smaller than the original.
    # I get under 10kB on my system for each font, but allow 15kB in case
    # of differences in the font files.
    assert {
        'CMEX10',
        'CMMI12',
        'CMR12',
        'CMSY10',
        'CMSY8',
        'EUFM10',
        'MSAM10',
        'MSBM10',
    }.issubset(length), "Missing expected fonts in the PDF"
    for font_name, length in length.items():
        assert length < 15_000, (
            f"Font {font_name}={length} is larger than expected"
        )

    # For comparison, lengths without subsetting on my system:
    #  'CMEX10': 29686
    #  'CMMI12': 36176
    #  'CMR12': 32157
    #  'CMSY10': 32004
    #  'CMSY8': 32061
    #  'EUFM10': 20546
    #  'MSAM10': 31199
    #  'MSBM10': 34129


try:
    _old_gs_version = mpl._get_executable_info('gs').version < parse_version('9.55')
except mpl.ExecutableNotFoundError:
    _old_gs_version = True


# TODO: tighten tolerance after baseline image is regenerated for text overhaul
@image_comparison(baseline_images=['rotation'], extensions=['eps', 'pdf', 'png', 'svg'],
                  style='mpl20', tol=3.91 if _old_gs_version else 0.2)
def test_rotation():
    mpl.rcParams['text.usetex'] = True

    fig = plt.figure()
    ax = fig.add_axes((0, 0, 1, 1))
    ax.set(xlim=(-0.5, 5), xticks=[], ylim=(-0.5, 3), yticks=[], frame_on=False)

    text = {val: val[0] for val in ['top', 'center', 'bottom', 'left', 'right']}
    text['baseline'] = 'B'
    text['center_baseline'] = 'C'

    for i, va in enumerate(['top', 'center', 'bottom', 'baseline', 'center_baseline']):
        for j, ha in enumerate(['left', 'center', 'right']):
            for k, angle in enumerate([0, 90, 180, 270]):
                k //= 2
                x = i + k / 2
                y = j + k / 2
                ax.plot(x, y, '+', c=f'C{k}', markersize=20, markeredgewidth=0.5)
                # 'My' checks full height letters plus descenders.
                ax.text(x, y, f"$\\mathrm{{My {text[ha]}{text[va]} {angle}}}$",
                        rotation=angle, horizontalalignment=ha, verticalalignment=va)


def test_unicode_sizing():
    tp = mpl.textpath.TextToPath()
    scale1 = tp.get_glyphs_tex(mpl.font_manager.FontProperties(), "W")[0][0][3]
    scale2 = tp.get_glyphs_tex(mpl.font_manager.FontProperties(), r"\textwon")[0][0][3]
    assert scale1 == scale2