"""
This is a backport and modernization of Cython's coverage.py support from the
3.* branch to the stable 0.29.* branch.

Most importantly for us, it includes support for coverage.py's `exclude_lines`
configuration option, allowing us to filter things like MemoryError from the
coverage reports.

It is standalone, and does not require Cython itself.

The complete license for this file can be found at:

    https://github.com/cython/cython/blob/0.29.22/LICENSE.txt

Changelog
---------

1.0.0
^^^^^
- Support for excluded_lines
- Fixed inconsistent quotations, PEP8'd.
"""
import io
import re
import os.path
import sys
from collections import defaultdict

from coverage.plugin import CoveragePlugin, FileTracer, FileReporter
from coverage.files import canonical_filename


C_FILE_EXTENSIONS = {'.c', '.cpp', '.cc', '.cxx'}
MODULE_FILE_EXTENSIONS = {'.py', '.pyx', '.pxd'} | C_FILE_EXTENSIONS


def is_package_dir(dir_path):
    for filename in ('__init__.py',
                     '__init__.pyc',
                     '__init__.pyx',
                     '__init__.pxd'):
        path = os.path.join(dir_path, filename)
        if path_exists(path):
            return 1


_match_file_encoding = re.compile(br'(\w*coding)[:=]\s*([-\w.]+)').search


def detect_opened_file_encoding(f):
    # PEPs 263 and 3120
    # Most of the time the first two lines fall in the first couple of hundred
    # chars, and this bulk read/split is much faster.
    lines = ()
    start = b''
    while len(lines) < 3:
        data = f.read(500)
        start += data
        lines = start.split(b'\n')
        if not data:
            break
    m = _match_file_encoding(lines[0])
    if m and m.group(1) != b'c_string_encoding':
        return m.group(2).decode('iso8859-1')
    elif len(lines) > 1:
        m = _match_file_encoding(lines[1])
        if m:
            return m.group(2).decode('iso8859-1')
    return 'UTF-8'


def path_exists(path):
    # try on the filesystem first
    if os.path.exists(path):
        return True
    # figure out if a PEP 302 loader is around
    try:
        loader = __loader__
        # XXX the code below assumes a 'zipimport.zipimporter' instance
        # XXX should be easy to generalize, but too lazy right now to write it
        archive_path = getattr(loader, 'archive', None)
        if archive_path:
            normpath = os.path.normpath(path)
            if normpath.startswith(archive_path):
                arcname = normpath[len(archive_path)+1:]
                try:
                    loader.get_data(arcname)
                    return True
                except IOError:
                    return False
    except NameError:
        pass
    return False


def find_root_package_dir(file_path):
    dir = os.path.dirname(file_path)
    if file_path == dir:
        return dir
    elif is_package_dir(dir):
        return find_root_package_dir(dir)
    else:
        return dir


def open_source_file(source_filename, encoding=None, error_handling=None):
    stream = None
    try:
        if encoding is None:
            # Most of the time the encoding is not specified, so try hard to
            # open the file only once.
            f = io.open(source_filename, 'rb')
            encoding = detect_opened_file_encoding(f)
            f.seek(0)
            stream = io.TextIOWrapper(
                f,
                encoding=encoding,
                errors=error_handling
            )
        else:
            stream = io.open(
                source_filename,
                encoding=encoding,
                errors=error_handling
            )

    except OSError:
        if os.path.exists(source_filename):
            raise  # File is there, but something went wrong reading from it.
        # Allow source files to be in zip files etc.
        try:
            loader = __loader__
            if source_filename.startswith(loader.archive):
                stream = open_source_from_loader(
                    loader, source_filename,
                    encoding, error_handling)
        except (NameError, AttributeError):
            pass

    if stream is None:
        raise FileNotFoundError(source_filename)

    if stream.read(1) != u'\uFEFF':
        stream.seek(0)

    return stream


def _find_c_source(base_path):
    file_exists = os.path.exists
    for ext in C_FILE_EXTENSIONS:
        file_name = base_path + ext
        if file_exists(file_name):
            return file_name
    return None


def _find_dep_file_path(main_file, file_path, relative_path_search=False):
    abs_path = os.path.abspath(file_path)
    if not os.path.exists(abs_path) and (file_path.endswith('.pxi') or
                                         relative_path_search):
        # files are looked up relative to the main source file
        rel_file_path = os.path.join(os.path.dirname(main_file), file_path)
        if os.path.exists(rel_file_path):
            abs_path = os.path.abspath(rel_file_path)

    # search sys.path for external locations if a valid file hasn't been found
    if not os.path.exists(abs_path):
        for sys_path in sys.path:
            test_path = os.path.realpath(os.path.join(sys_path, file_path))
            if os.path.exists(test_path):
                return canonical_filename(test_path)

    return canonical_filename(abs_path)


class Plugin(CoveragePlugin):
    # map from traced file paths to absolute file paths
    _file_path_map = None
    # map from traced file paths to corresponding C files
    _c_files_map = None
    # map from parsed C files to their content
    _parsed_c_files = None
    # map from traced files to lines that are excluded from coverage
    _excluded_lines_map = None
    # list of regex patterns for lines to exclude
    _excluded_line_patterns = ()

    def sys_info(self):
        return []

    def configure(self, config):
        # Entry point for coverage "configurer".
        # Read the regular expressions from the coverage config that match
        # lines to be excluded from coverage.
        self._excluded_line_patterns = config.get_option(
            'report:exclude_lines'
        )

    def file_tracer(self, filename):
        """
        Try to find a C source file for a file path found by the tracer.
        """
        if filename.startswith('<') or filename.startswith('memory:'):
            return None
        c_file = py_file = None
        filename = canonical_filename(os.path.abspath(filename))
        if self._c_files_map and filename in self._c_files_map:
            c_file = self._c_files_map[filename][0]

        if c_file is None:
            c_file, py_file = self._find_source_files(filename)
            if not c_file:
                return None  # unknown file

            # parse all source file paths and lines from C file
            # to learn about all relevant source files right away (pyx/pxi/pxd)
            # FIXME: this might already be too late if the first executed line
            #        is not from the main .pyx file but a file with a different
            #        name than the .c file (which prevents us from finding the
            #        .c file)
            _, code = self._read_source_lines(c_file, filename)
            if code is None:
                return None  # no source found

        if self._file_path_map is None:
            self._file_path_map = {}

        return CythonModuleTracer(
            filename,
            py_file,
            c_file,
            self._c_files_map,
            self._file_path_map
        )

    def file_reporter(self, filename):
        # TODO: let coverage.py handle .py files itself
        # ext = os.path.splitext(filename)[1].lower()
        # if ext == '.py':
        #     from coverage.python import PythonFileReporter
        #     return PythonFileReporter(filename)

        filename = canonical_filename(os.path.abspath(filename))
        if self._c_files_map and filename in self._c_files_map:
            c_file, rel_file_path, code = self._c_files_map[filename]
        else:
            c_file, _ = self._find_source_files(filename)
            if not c_file:
                return None  # unknown file

            rel_file_path, code = self._read_source_lines(c_file, filename)
            if code is None:
                return None  # no source found

        return CythonModuleReporter(
            c_file,
            filename,
            rel_file_path,
            code,
            self._excluded_lines_map.get(rel_file_path, frozenset())
        )

    def _find_source_files(self, filename):
        basename, ext = os.path.splitext(filename)
        ext = ext.lower()
        if ext in MODULE_FILE_EXTENSIONS:
            pass
        elif ext == '.pyd':
            # Windows extension module
            platform_suffix = re.search(
                r'[.]cp[0-9]+-win[_a-z0-9]*$',
                basename,
                re.I
            )

            if platform_suffix:
                basename = basename[:platform_suffix.start()]
        elif ext == '.so':
            # Linux/Unix/Mac extension module
            platform_suffix = re.search(
                r'[.](?:cpython|pypy)-[0-9]+[-_a-z0-9]*$',
                basename,
                re.I
            )

            if platform_suffix:
                basename = basename[:platform_suffix.start()]
        elif ext == '.pxi':
            # if we get here, it means that the first traced line of a Cython
            # module was not in the main module but in an include file, so try
            # a little harder to find the main source file
            self._find_c_source_files(os.path.dirname(filename), filename)
            if filename in self._c_files_map:
                return self._c_files_map[filename][0], None
        else:
            # none of our business
            return None, None

        if ext in C_FILE_EXTENSIONS:
            c_file = filename
        else:
            c_file = _find_c_source(basename)

        if c_file is None:
            # a module "pkg/mod.so" can have a source file "pkg/pkg.mod.c"
            package_root = find_root_package_dir(filename)
            package_path = os.path.relpath(
                basename,
                package_root
            ).split(os.path.sep)

            if len(package_path) > 1:
                test_basepath = os.path.join(
                    os.path.dirname(filename),
                    '.'.join(package_path)
                )
                c_file = _find_c_source(test_basepath)

        py_source_file = None
        if c_file:
            py_source_file = os.path.splitext(c_file)[0] + '.py'
            if not os.path.exists(py_source_file):
                py_source_file = None

            try:
                with open(c_file, 'rb') as f:
                    if b'/* Generated by Cython ' not in f.read(30):
                        return None, None  # not a Cython file
            except (IOError, OSError):
                c_file = None

        return c_file, py_source_file

    def _find_c_source_files(self, dir_path, source_file):
        """
        Desperately parse all C files in the directory or its package parents
        (not re-descending) to find the (included) source file in one of them.
        """
        if not os.path.isdir(dir_path):
            return

        splitext = os.path.splitext
        for filename in os.listdir(dir_path):
            ext = splitext(filename)[1].lower()
            if ext in C_FILE_EXTENSIONS:
                self._read_source_lines(
                    os.path.join(dir_path, filename),
                    source_file
                )
                if source_file in self._c_files_map:
                    return

        # not found? then try one package up
        if is_package_dir(dir_path):
            self._find_c_source_files(os.path.dirname(dir_path), source_file)

    def _read_source_lines(self, c_file, sourcefile):
        """
        Parse a Cython generated C/C++ source file and find the executable
        lines.  Each executable line starts with a comment header that states
        source file and line number, as well as the surrounding range of source
        code lines.
        """
        if self._parsed_c_files is None:
            self._parsed_c_files = {}
        if c_file in self._parsed_c_files:
            code_lines = self._parsed_c_files[c_file]
        else:
            code_lines = self._parse_cfile_lines(c_file)
            self._parsed_c_files[c_file] = code_lines

        if self._c_files_map is None:
            self._c_files_map = {}

        for filename, code in code_lines.items():
            abs_path = _find_dep_file_path(c_file, filename,
                                           relative_path_search=True)
            self._c_files_map[abs_path] = (c_file, filename, code)

        if sourcefile not in self._c_files_map:
            return (None,) * 2  # e.g. shared library file
        return self._c_files_map[sourcefile][1:]

    def _parse_cfile_lines(self, c_file):
        """
        Parse a C file and extract all source file lines that generated
        executable code.
        """
        match_source_path_line = re.compile(r' */[*] +"(.*)":([0-9]+)$').match
        match_current_code_line = re.compile(r' *[*] (.*) # <<<<<<+$').match
        match_comment_end = re.compile(r' *[*]/$').match
        match_trace_line = re.compile(r' *__Pyx_TraceLine\(([0-9]+),').match
        not_executable = re.compile(
            r'\s*c(?:type)?def\s+'
            r'(?:(?:public|external)\s+)?'
            r'(?:struct|union|enum|class)'
            r'(\s+[^:]+|)\s*:'
        ).match

        line_is_excluded = None
        if self._excluded_line_patterns:
            line_is_excluded = re.compile(
                '|'.join([
                    '(?:{0})'.format(regex)
                    for regex in self._excluded_line_patterns
                ])
            ).search

        code_lines = defaultdict(dict)
        executable_lines = defaultdict(set)
        current_filename = None

        if self._excluded_lines_map is None:
            self._excluded_lines_map = defaultdict(set)

        with open(c_file) as lines:
            lines = iter(lines)
            for line in lines:
                match = match_source_path_line(line)
                if not match:
                    if ('__Pyx_TraceLine(' in line and
                            current_filename is not None):
                        trace_line = match_trace_line(line)
                        if trace_line:
                            executable_lines[current_filename].add(
                                int(trace_line.group(1))
                            )
                    continue

                filename, lineno = match.groups()
                current_filename = filename
                lineno = int(lineno)
                for comment_line in lines:
                    match = match_current_code_line(comment_line)
                    if match:
                        code_line = match.group(1).rstrip()
                        if not_executable(code_line):
                            break
                        if (line_is_excluded is not None and
                                line_is_excluded(code_line)):
                            self._excluded_lines_map[filename].add(lineno)
                            break
                        code_lines[filename][lineno] = code_line
                        break
                    elif match_comment_end(comment_line):
                        # unexpected comment format - false positive?
                        break

        # Remove lines that generated code but are not traceable.
        for filename, lines in code_lines.items():
            dead_lines = set(lines).difference(
                executable_lines.get(filename, ())
            )
            for lineno in dead_lines:
                del lines[lineno]
        return code_lines


class CythonModuleTracer(FileTracer):
    """
    Find the Python/Cython source file for a Cython module.
    """
    def __init__(self, module_file, py_file, c_file, c_files_map,
                 file_path_map):
        super(CythonModuleTracer, self).__init__()
        self.module_file = module_file
        self.py_file = py_file
        self.c_file = c_file
        self._c_files_map = c_files_map
        self._file_path_map = file_path_map

    def has_dynamic_source_filename(self):
        return True

    def dynamic_source_filename(self, filename, frame):
        """
        Determine source file path.  Called by the function call tracer.
        """
        source_file = frame.f_code.co_filename
        try:
            return self._file_path_map[source_file]
        except KeyError:
            pass

        abs_path = _find_dep_file_path(filename, source_file)

        if self.py_file and source_file[-3:].lower() == '.py':
            # always let coverage.py handle this case itself
            self._file_path_map[source_file] = self.py_file
            return self.py_file

        assert self._c_files_map is not None
        if abs_path not in self._c_files_map:
            self._c_files_map[abs_path] = (self.c_file, source_file, None)
        self._file_path_map[source_file] = abs_path
        return abs_path


class CythonModuleReporter(FileReporter):
    """
    Provide detailed trace information for one source file to coverage.py.
    """
    def __init__(self, c_file, source_file, rel_file_path, code,
                 excluded_lines):
        super(CythonModuleReporter, self).__init__(source_file)
        self.name = rel_file_path
        self.c_file = c_file
        self._code = code
        self._excluded_lines = excluded_lines

    def lines(self):
        """
        Return set of line numbers that are possibly executable.
        """
        return set(self._code)

    def excluded_lines(self):
        """
        Return set of line numbers that are excluded from coverage.
        """
        return self._excluded_lines

    def _iter_source_tokens(self):
        current_line = 1
        for line_no, code_line in sorted(self._code.items()):
            while line_no > current_line:
                yield []
                current_line += 1
            yield [('txt', code_line)]
            current_line += 1

    def source(self):
        """
        Return the source code of the file as a string.
        """
        if os.path.exists(self.filename):
            with open_source_file(self.filename) as f:
                return f.read()
        else:
            return '\n'.join(
                (tokens[0][1] if tokens else '')
                for tokens in self._iter_source_tokens())

    def source_token_lines(self):
        """
        Iterate over the source code tokens.
        """
        if os.path.exists(self.filename):
            with open_source_file(self.filename) as f:
                for line in f:
                    yield [('txt', line.rstrip('\n'))]
        else:
            for line in self._iter_source_tokens():
                yield [('txt', line)]


def coverage_init(reg, options):
    plugin = Plugin()
    reg.add_configurer(plugin)
    reg.add_file_tracer(plugin)
