"""
This is a python interface to Adobe Font Metrics Files.  Although a
number of other python implementations exist, and may be more complete
than this, it was decided not to go with them because they were
either:

  1) copyrighted or used a non-BSD compatible license

  2) had too many dependencies and a free standing lib was needed

  3) Did more than needed and it was easier to write afresh rather than
     figure out how to get just what was needed.

It is pretty easy to use, and requires only built-in python libs:

    >>> from matplotlib import rcParams
    >>> import os.path
    >>> afm_fname = os.path.join(rcParams['datapath'],
    ...                         'fonts', 'afm', 'ptmr8a.afm')
    >>>
    >>> from matplotlib.afm import AFM
    >>> with open(afm_fname) as fh:
    ...     afm = AFM(fh)
    >>> afm.string_width_height('What the heck?')
    (6220.0, 694)
    >>> afm.get_fontname()
    'Times-Roman'
    >>> afm.get_kern_dist('A', 'f')
    0
    >>> afm.get_kern_dist('A', 'y')
    -92.0
    >>> afm.get_bbox_char('!')
    [130, -9, 238, 676]

"""

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)

import six
from six.moves import map

import sys
import os
import re
from ._mathtext_data import uni2type1

# Convert string the a python type

# some afm files have floats where we are expecting ints -- there is
# probably a better way to handle this (support floats, round rather
# than truncate).  But I don't know what the best approach is now and
# this change to _to_int should at least prevent mpl from crashing on
# these JDH (2009-11-06)


def _to_int(x):
    return int(float(x))


_to_float = float


def _to_str(x):
    return x.decode('utf8')


def _to_list_of_ints(s):
    s = s.replace(b',', b' ')
    return [_to_int(val) for val in s.split()]


def _to_list_of_floats(s):
    return [_to_float(val) for val in s.split()]


def _to_bool(s):
    if s.lower().strip() in (b'false', b'0', b'no'):
        return False
    else:
        return True


def _sanity_check(fh):
    """
    Check if the file at least looks like AFM.
    If not, raise :exc:`RuntimeError`.
    """

    # Remember the file position in case the caller wants to
    # do something else with the file.
    pos = fh.tell()
    try:
        line = next(fh)
    finally:
        fh.seek(pos, 0)

    # AFM spec, Section 4: The StartFontMetrics keyword [followed by a
    # version number] must be the first line in the file, and the
    # EndFontMetrics keyword must be the last non-empty line in the
    # file. We just check the first line.
    if not line.startswith(b'StartFontMetrics'):
        raise RuntimeError('Not an AFM file')


def _parse_header(fh):
    """
    Reads the font metrics header (up to the char metrics) and returns
    a dictionary mapping *key* to *val*.  *val* will be converted to the
    appropriate python type as necessary; e.g.:

        * 'False'->False
        * '0'->0
        * '-168 -218 1000 898'-> [-168, -218, 1000, 898]

    Dictionary keys are

      StartFontMetrics, FontName, FullName, FamilyName, Weight,
      ItalicAngle, IsFixedPitch, FontBBox, UnderlinePosition,
      UnderlineThickness, Version, Notice, EncodingScheme, CapHeight,
      XHeight, Ascender, Descender, StartCharMetrics

    """
    headerConverters = {
        b'StartFontMetrics': _to_float,
        b'FontName': _to_str,
        b'FullName': _to_str,
        b'FamilyName': _to_str,
        b'Weight': _to_str,
        b'ItalicAngle': _to_float,
        b'IsFixedPitch': _to_bool,
        b'FontBBox': _to_list_of_ints,
        b'UnderlinePosition': _to_int,
        b'UnderlineThickness': _to_int,
        b'Version': _to_str,
        b'Notice': _to_str,
        b'EncodingScheme': _to_str,
        b'CapHeight': _to_float,  # Is the second version a mistake, or
        b'Capheight': _to_float,  # do some AFM files contain 'Capheight'? -JKS
        b'XHeight': _to_float,
        b'Ascender': _to_float,
        b'Descender': _to_float,
        b'StdHW': _to_float,
        b'StdVW': _to_float,
        b'StartCharMetrics': _to_int,
        b'CharacterSet': _to_str,
        b'Characters': _to_int,
        }

    d = {}
    for line in fh:
        line = line.rstrip()
        if line.startswith(b'Comment'):
            continue
        lst = line.split(b' ', 1)

        key = lst[0]
        if len(lst) == 2:
            val = lst[1]
        else:
            val = b''

        try:
            d[key] = headerConverters[key](val)
        except ValueError:
            print('Value error parsing header in AFM:',
                  key, val, file=sys.stderr)
            continue
        except KeyError:
            print('Found an unknown keyword in AFM header (was %r)' % key,
                  file=sys.stderr)
            continue
        if key == b'StartCharMetrics':
            return d
    raise RuntimeError('Bad parse')


def _parse_char_metrics(fh):
    """
    Return a character metric dictionary.  Keys are the ASCII num of
    the character, values are a (*wx*, *name*, *bbox*) tuple, where
    *wx* is the character width, *name* is the postscript language
    name, and *bbox* is a (*llx*, *lly*, *urx*, *ury*) tuple.

    This function is incomplete per the standard, but thus far parses
    all the sample afm files tried.
    """

    ascii_d = {}
    name_d = {}
    for line in fh:
        # We are defensively letting values be utf8. The spec requires
        # ascii, but there are non-compliant fonts in circulation
        line = _to_str(line.rstrip())  # Convert from byte-literal
        if line.startswith('EndCharMetrics'):
            return ascii_d, name_d
        # Split the metric line into a dictionary, keyed by metric identifiers
        vals = dict(s.strip().split(' ', 1) for s in line.split(';') if s)
        # There may be other metrics present, but only these are needed
        if not {'C', 'WX', 'N', 'B'}.issubset(vals):
            raise RuntimeError('Bad char metrics line: %s' % line)
        num = _to_int(vals['C'])
        wx = _to_float(vals['WX'])
        name = vals['N']
        bbox = _to_list_of_floats(vals['B'])
        bbox = list(map(int, bbox))
        # Workaround: If the character name is 'Euro', give it the
        # corresponding character code, according to WinAnsiEncoding (see PDF
        # Reference).
        if name == 'Euro':
            num = 128
        if num != -1:
            ascii_d[num] = (wx, name, bbox)
        name_d[name] = (wx, bbox)
    raise RuntimeError('Bad parse')


def _parse_kern_pairs(fh):
    """
    Return a kern pairs dictionary; keys are (*char1*, *char2*) tuples and
    values are the kern pair value.  For example, a kern pairs line like
    ``KPX A y -50``

    will be represented as::

      d[ ('A', 'y') ] = -50

    """

    line = next(fh)
    if not line.startswith(b'StartKernPairs'):
        raise RuntimeError('Bad start of kern pairs data: %s' % line)

    d = {}
    for line in fh:
        line = line.rstrip()
        if not line:
            continue
        if line.startswith(b'EndKernPairs'):
            next(fh)  # EndKernData
            return d
        vals = line.split()
        if len(vals) != 4 or vals[0] != b'KPX':
            raise RuntimeError('Bad kern pairs line: %s' % line)
        c1, c2, val = _to_str(vals[1]), _to_str(vals[2]), _to_float(vals[3])
        d[(c1, c2)] = val
    raise RuntimeError('Bad kern pairs parse')


def _parse_composites(fh):
    """
    Return a composites dictionary.  Keys are the names of the
    composites.  Values are a num parts list of composite information,
    with each element being a (*name*, *dx*, *dy*) tuple.  Thus a
    composites line reading:

      CC Aacute 2 ; PCC A 0 0 ; PCC acute 160 170 ;

    will be represented as::

      d['Aacute'] = [ ('A', 0, 0), ('acute', 160, 170) ]

    """
    d = {}
    for line in fh:
        line = line.rstrip()
        if not line:
            continue
        if line.startswith(b'EndComposites'):
            return d
        vals = line.split(b';')
        cc = vals[0].split()
        name, numParts = cc[1], _to_int(cc[2])
        pccParts = []
        for s in vals[1:-1]:
            pcc = s.split()
            name, dx, dy = pcc[1], _to_float(pcc[2]), _to_float(pcc[3])
            pccParts.append((name, dx, dy))
        d[name] = pccParts

    raise RuntimeError('Bad composites parse')


def _parse_optional(fh):
    """
    Parse the optional fields for kern pair data and composites

    return value is a (*kernDict*, *compositeDict*) which are the
    return values from :func:`_parse_kern_pairs`, and
    :func:`_parse_composites` if the data exists, or empty dicts
    otherwise
    """
    optional = {
        b'StartKernData': _parse_kern_pairs,
        b'StartComposites':  _parse_composites,
        }

    d = {b'StartKernData': {}, b'StartComposites': {}}
    for line in fh:
        line = line.rstrip()
        if not line:
            continue
        key = line.split()[0]

        if key in optional:
            d[key] = optional[key](fh)

    l = (d[b'StartKernData'], d[b'StartComposites'])
    return l


def parse_afm(fh):
    """
    Parse the Adobe Font Metics file in file handle *fh*. Return value
    is a (*dhead*, *dcmetrics_ascii*, *dmetrics_name*, *dkernpairs*,
    *dcomposite*) tuple where
    *dhead* is a :func:`_parse_header` dict,
    *dcmetrics_ascii* and *dcmetrics_name* are the two resulting dicts
    from :func:`_parse_char_metrics`,
    *dkernpairs* is a :func:`_parse_kern_pairs` dict (possibly {}) and
    *dcomposite* is a :func:`_parse_composites` dict (possibly {})
    """
    _sanity_check(fh)
    dhead = _parse_header(fh)
    dcmetrics_ascii, dcmetrics_name = _parse_char_metrics(fh)
    doptional = _parse_optional(fh)
    return dhead, dcmetrics_ascii, dcmetrics_name, doptional[0], doptional[1]


class AFM(object):

    def __init__(self, fh):
        """
        Parse the AFM file in file object *fh*
        """
        (dhead, dcmetrics_ascii, dcmetrics_name, dkernpairs, dcomposite) = \
            parse_afm(fh)
        self._header = dhead
        self._kern = dkernpairs
        self._metrics = dcmetrics_ascii
        self._metrics_by_name = dcmetrics_name
        self._composite = dcomposite

    def get_bbox_char(self, c, isord=False):
        if not isord:
            c = ord(c)
        wx, name, bbox = self._metrics[c]
        return bbox

    def string_width_height(self, s):
        """
        Return the string width (including kerning) and string height
        as a (*w*, *h*) tuple.
        """
        if not len(s):
            return 0, 0
        totalw = 0
        namelast = None
        miny = 1e9
        maxy = 0
        for c in s:
            if c == '\n':
                continue
            wx, name, bbox = self._metrics[ord(c)]
            l, b, w, h = bbox

            # find the width with kerning
            try:
                kp = self._kern[(namelast, name)]
            except KeyError:
                kp = 0
            totalw += wx + kp

            # find the max y
            thismax = b + h
            if thismax > maxy:
                maxy = thismax

            # find the min y
            thismin = b
            if thismin < miny:
                miny = thismin
            namelast = name

        return totalw, maxy - miny

    def get_str_bbox_and_descent(self, s):
        """
        Return the string bounding box
        """
        if not len(s):
            return 0, 0, 0, 0
        totalw = 0
        namelast = None
        miny = 1e9
        maxy = 0
        left = 0
        if not isinstance(s, six.text_type):
            s = _to_str(s)
        for c in s:
            if c == '\n':
                continue
            name = uni2type1.get(ord(c), 'question')
            try:
                wx, bbox = self._metrics_by_name[name]
            except KeyError:
                name = 'question'
                wx, bbox = self._metrics_by_name[name]
            l, b, w, h = bbox
            if l < left:
                left = l
            # find the width with kerning
            try:
                kp = self._kern[(namelast, name)]
            except KeyError:
                kp = 0
            totalw += wx + kp

            # find the max y
            thismax = b + h
            if thismax > maxy:
                maxy = thismax

            # find the min y
            thismin = b
            if thismin < miny:
                miny = thismin
            namelast = name

        return left, miny, totalw, maxy - miny, -miny

    def get_str_bbox(self, s):
        """
        Return the string bounding box
        """
        return self.get_str_bbox_and_descent(s)[:4]

    def get_name_char(self, c, isord=False):
        """
        Get the name of the character, i.e., ';' is 'semicolon'
        """
        if not isord:
            c = ord(c)
        wx, name, bbox = self._metrics[c]
        return name

    def get_width_char(self, c, isord=False):
        """
        Get the width of the character from the character metric WX
        field
        """
        if not isord:
            c = ord(c)
        wx, name, bbox = self._metrics[c]
        return wx

    def get_width_from_char_name(self, name):
        """
        Get the width of the character from a type1 character name
        """
        wx, bbox = self._metrics_by_name[name]
        return wx

    def get_height_char(self, c, isord=False):
        """
        Get the height of character *c* from the bounding box.  This
        is the ink height (space is 0)
        """
        if not isord:
            c = ord(c)
        wx, name, bbox = self._metrics[c]
        return bbox[-1]

    def get_kern_dist(self, c1, c2):
        """
        Return the kerning pair distance (possibly 0) for chars *c1*
        and *c2*
        """
        name1, name2 = self.get_name_char(c1), self.get_name_char(c2)
        return self.get_kern_dist_from_name(name1, name2)

    def get_kern_dist_from_name(self, name1, name2):
        """
        Return the kerning pair distance (possibly 0) for chars
        *name1* and *name2*
        """
        return self._kern.get((name1, name2), 0)

    def get_fontname(self):
        "Return the font name, e.g., 'Times-Roman'"
        return self._header[b'FontName']

    def get_fullname(self):
        "Return the font full name, e.g., 'Times-Roman'"
        name = self._header.get(b'FullName')
        if name is None:  # use FontName as a substitute
            name = self._header[b'FontName']
        return name

    def get_familyname(self):
        "Return the font family name, e.g., 'Times'"
        name = self._header.get(b'FamilyName')
        if name is not None:
            return name

        # FamilyName not specified so we'll make a guess
        name = self.get_fullname()
        extras = (r'(?i)([ -](regular|plain|italic|oblique|bold|semibold|'
                  r'light|ultralight|extra|condensed))+$')
        return re.sub(extras, '', name)

    @property
    def family_name(self):
        return self.get_familyname()

    def get_weight(self):
        "Return the font weight, e.g., 'Bold' or 'Roman'"
        return self._header[b'Weight']

    def get_angle(self):
        "Return the fontangle as float"
        return self._header[b'ItalicAngle']

    def get_capheight(self):
        "Return the cap height as float"
        return self._header[b'CapHeight']

    def get_xheight(self):
        "Return the xheight as float"
        return self._header[b'XHeight']

    def get_underline_thickness(self):
        "Return the underline thickness as float"
        return self._header[b'UnderlineThickness']

    def get_horizontal_stem_width(self):
        """
        Return the standard horizontal stem width as float, or *None* if
        not specified in AFM file.
        """
        return self._header.get(b'StdHW', None)

    def get_vertical_stem_width(self):
        """
        Return the standard vertical stem width as float, or *None* if
        not specified in AFM file.
        """
        return self._header.get(b'StdVW', None)
