"""
A Cython plugin for coverage.py

Requires the coverage package at least in version 4.0 (which added the plugin API).
"""

import re
import os.path
from collections import defaultdict

from coverage.plugin import CoveragePlugin, FileTracer, FileReporter  # requires coverage.py 4.0+

from .Utils import find_root_package_dir, is_package_dir, open_source_file


from . import __version__


def _find_c_source(base_path):
    if os.path.exists(base_path + '.c'):
        c_file = base_path + '.c'
    elif os.path.exists(base_path + '.cpp'):
        c_file = base_path + '.cpp'
    else:
        c_file = None
    return c_file


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

    def sys_info(self):
        return [('Cython version', __version__)]

    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 = 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

            # 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)
            self._parse_lines(c_file, filename)

        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):
        if os.path.splitext(filename)[1].lower() not in ('.pyx', '.pxi', '.pxd'):
            return None  # let coverage.py handle it (e.g. .py files)

        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._parse_lines(c_file, filename)
        return CythonModuleReporter(c_file, filename, rel_file_path, code)

    def _find_source_files(self, filename):
        basename, ext = os.path.splitext(filename)
        ext = ext.lower()
        if ext in ('.py', '.pyx', '.pxd', '.c', '.cpp'):
            pass
        elif ext in ('.so', '.pyd'):
            platform_suffix = re.search(r'[.]cpython-[0-9]+[a-z]*$', 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

        c_file = filename if ext in ('.c', '.cpp') else _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.uncached(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  # 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', '.cpp'):
                self._parse_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 _parse_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:
            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
            not_executable = re.compile(
                r'\s*c(?:type)?def\s+'
                r'(?:(?:public|external)\s+)?'
                r'(?:struct|union|enum|class)'
                r'(\s+[^:]+|)\s*:'
            ).match

            code_lines = defaultdict(dict)
            filenames = set()
            with open(c_file) as lines:
                lines = iter(lines)
                for line in lines:
                    match = match_source_path_line(line)
                    if not match:
                        continue
                    filename, lineno = match.groups()
                    filenames.add(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
                            code_lines[filename][lineno] = code_line
                            break
                        elif match_comment_end(comment_line):
                            # unexpected comment format - false positive?
                            break

            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.iteritems():
            abs_path = _find_dep_file_path(c_file, filename)
            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:]


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 = os.path.abspath(source_file)

        if self.py_file and source_file.lower().endswith('.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):
        super(CythonModuleReporter, self).__init__(source_file)
        self.name = rel_file_path
        self.c_file = c_file
        self._code = code

    def statements(self):
        return self._code.viewkeys()

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

    def source(self):
        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):
        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)]
