"""Analyze python import statements."""
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

import ast
import os

from . import types as t

from .io import (
    read_binary_file,
)

from .util import (
    display,
    ApplicationError,
    is_subdir,
)

from .data import (
    data_context,
)

VIRTUAL_PACKAGES = set([
    'ansible.module_utils.six',
])


def get_python_module_utils_imports(compile_targets):
    """Return a dictionary of module_utils names mapped to sets of python file paths.
    :type compile_targets: list[TestTarget]
    :rtype: dict[str, set[str]]
    """

    module_utils = enumerate_module_utils()

    virtual_utils = set(m for m in module_utils if any(m.startswith('%s.' % v) for v in VIRTUAL_PACKAGES))
    module_utils -= virtual_utils

    imports_by_target_path = {}

    for target in compile_targets:
        imports_by_target_path[target.path] = extract_python_module_utils_imports(target.path, module_utils)

    def recurse_import(import_name, depth=0, seen=None):  # type: (str, int, t.Optional[t.Set[str]]) -> t.Set[str]
        """Recursively expand module_utils imports from module_utils files."""
        display.info('module_utils import: %s%s' % ('  ' * depth, import_name), verbosity=4)

        if seen is None:
            seen = set([import_name])

        results = set([import_name])

        # virtual packages depend on the modules they contain instead of the reverse
        if import_name in VIRTUAL_PACKAGES:
            for sub_import in sorted(virtual_utils):
                if sub_import.startswith('%s.' % import_name):
                    if sub_import in seen:
                        continue

                    seen.add(sub_import)

                    matches = sorted(recurse_import(sub_import, depth + 1, seen))

                    for result in matches:
                        results.add(result)

        import_path = get_import_path(import_name)

        if import_path not in imports_by_target_path:
            import_path = get_import_path(import_name, package=True)

            if import_path not in imports_by_target_path:
                raise ApplicationError('Cannot determine path for module_utils import: %s' % import_name)

        # process imports in reverse so the deepest imports come first
        for name in sorted(imports_by_target_path[import_path], reverse=True):
            if name in virtual_utils:
                continue

            if name in seen:
                continue

            seen.add(name)

            matches = sorted(recurse_import(name, depth + 1, seen))

            for result in matches:
                results.add(result)

        return results

    for module_util in module_utils:
        # recurse over module_utils imports while excluding self
        module_util_imports = recurse_import(module_util)
        module_util_imports.remove(module_util)

        # add recursive imports to all path entries which import this module_util
        for target_path in imports_by_target_path:
            if module_util in imports_by_target_path[target_path]:
                for module_util_import in sorted(module_util_imports):
                    if module_util_import not in imports_by_target_path[target_path]:
                        display.info('%s inherits import %s via %s' % (target_path, module_util_import, module_util), verbosity=6)
                        imports_by_target_path[target_path].add(module_util_import)

    imports = dict([(module_util, set()) for module_util in module_utils | virtual_utils])

    for target_path in imports_by_target_path:
        for module_util in imports_by_target_path[target_path]:
            imports[module_util].add(target_path)

    # for purposes of mapping module_utils to paths, treat imports of virtual utils the same as the parent package
    for virtual_util in virtual_utils:
        parent_package = '.'.join(virtual_util.split('.')[:-1])
        imports[virtual_util] = imports[parent_package]
        display.info('%s reports imports from parent package %s' % (virtual_util, parent_package), verbosity=6)

    for module_util in sorted(imports):
        if not imports[module_util]:
            display.warning('No imports found which use the "%s" module_util.' % module_util)

    return imports


def get_python_module_utils_name(path):  # type: (str) -> str
    """Return a namespace and name from the given module_utils path."""
    base_path = data_context().content.module_utils_path

    if data_context().content.collection:
        prefix = 'ansible_collections.' + data_context().content.collection.prefix + 'plugins.module_utils.'
    else:
        prefix = 'ansible.module_utils.'

    if path.endswith('/__init__.py'):
        path = os.path.dirname(path)

    name = prefix + os.path.splitext(os.path.relpath(path, base_path))[0].replace(os.path.sep, '.')

    return name


def enumerate_module_utils():
    """Return a list of available module_utils imports.
    :rtype: set[str]
    """
    module_utils = []

    for path in data_context().content.walk_files(data_context().content.module_utils_path):
        ext = os.path.splitext(path)[1]

        if ext != '.py':
            continue

        if os.path.getsize(path) == 0:
            continue

        module_utils.append(get_python_module_utils_name(path))

    return set(module_utils)


def extract_python_module_utils_imports(path, module_utils):
    """Return a list of module_utils imports found in the specified source file.
    :type path: str
    :type module_utils: set[str]
    :rtype: set[str]
    """
    # Python code must be read as bytes to avoid a SyntaxError when the source uses comments to declare the file encoding.
    # See: https://www.python.org/dev/peps/pep-0263
    # Specifically: If a Unicode string with a coding declaration is passed to compile(), a SyntaxError will be raised.
    code = read_binary_file(path)

    try:
        tree = ast.parse(code)
    except SyntaxError as ex:
        # Treat this error as a warning so tests can be executed as best as possible.
        # The compile test will detect and report this syntax error.
        display.warning('%s:%s Syntax error extracting module_utils imports: %s' % (path, ex.lineno, ex.msg))
        return set()

    finder = ModuleUtilFinder(path, module_utils)
    finder.visit(tree)
    return finder.imports


def get_import_path(name, package=False):  # type: (str, bool) -> str
    """Return a path from an import name."""
    if package:
        filename = os.path.join(name.replace('.', '/'), '__init__.py')
    else:
        filename = '%s.py' % name.replace('.', '/')

    if name.startswith('ansible.module_utils.'):
        path = os.path.join('lib', filename)
    elif data_context().content.collection and name.startswith('ansible_collections.%s.plugins.module_utils.' % data_context().content.collection.full_name):
        path = '/'.join(filename.split('/')[3:])
    else:
        raise Exception('Unexpected import name: %s' % name)

    return path


class ModuleUtilFinder(ast.NodeVisitor):
    """AST visitor to find valid module_utils imports."""
    def __init__(self, path, module_utils):
        """Return a list of module_utils imports found in the specified source file.
        :type path: str
        :type module_utils: set[str]
        """
        self.path = path
        self.module_utils = module_utils
        self.imports = set()

        # implicitly import parent package

        if path.endswith('/__init__.py'):
            path = os.path.split(path)[0]

        if path.startswith('lib/ansible/module_utils/'):
            package = os.path.split(path)[0].replace('/', '.')[4:]

            if package != 'ansible.module_utils' and package not in VIRTUAL_PACKAGES:
                self.add_import(package, 0)

    # noinspection PyPep8Naming
    # pylint: disable=locally-disabled, invalid-name
    def visit_Import(self, node):
        """
        :type node: ast.Import
        """
        self.generic_visit(node)

        # import ansible.module_utils.MODULE[.MODULE]
        # import ansible_collections.{ns}.{col}.plugins.module_utils.module_utils.MODULE[.MODULE]
        self.add_imports([alias.name for alias in node.names], node.lineno)

    # noinspection PyPep8Naming
    # pylint: disable=locally-disabled, invalid-name
    def visit_ImportFrom(self, node):
        """
        :type node: ast.ImportFrom
        """
        self.generic_visit(node)

        if not node.module:
            return

        if not node.module.startswith('ansible'):
            return

        # from ansible.module_utils import MODULE[, MODULE]
        # from ansible.module_utils.MODULE[.MODULE] import MODULE[, MODULE]
        # from ansible_collections.{ns}.{col}.plugins.module_utils import MODULE[, MODULE]
        # from ansible_collections.{ns}.{col}.plugins.module_utils.MODULE[.MODULE] import MODULE[, MODULE]
        self.add_imports(['%s.%s' % (node.module, alias.name) for alias in node.names], node.lineno)

    def add_import(self, name, line_number):
        """
        :type name: str
        :type line_number: int
        """
        import_name = name

        while self.is_module_util_name(name):
            if name in self.module_utils:
                if name not in self.imports:
                    display.info('%s:%d imports module_utils: %s' % (self.path, line_number, name), verbosity=5)
                    self.imports.add(name)

                return  # duplicate imports are ignored

            name = '.'.join(name.split('.')[:-1])

        if is_subdir(self.path, data_context().content.test_path):
            return  # invalid imports in tests are ignored

        # Treat this error as a warning so tests can be executed as best as possible.
        # This error should be detected by unit or integration tests.
        display.warning('%s:%d Invalid module_utils import: %s' % (self.path, line_number, import_name))

    def add_imports(self, names, line_no):  # type: (t.List[str], int) -> None
        """Add the given import names if they are module_utils imports."""
        for name in names:
            if self.is_module_util_name(name):
                self.add_import(name, line_no)

    @staticmethod
    def is_module_util_name(name):  # type: (str) -> bool
        """Return True if the given name is a module_util name for the content under test. External module_utils are ignored."""
        if data_context().content.is_ansible and name.startswith('ansible.module_utils.'):
            return True

        if data_context().content.collection and name.startswith('ansible_collections.%s.plugins.module_utils.' % data_context().content.collection.full_name):
            return True

        return False