import os
import re
import sys
import shutil
from docs.docs_writer import DocsWriter

# Small trick so importing telethon_generator works
sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..'))

from telethon_generator.parser import TLParser, TLObject


# TLObject -> Python class name
def get_class_name(tlobject):
    """Gets the class name following the Python style guidelines, in ThisClassFormat"""
    # Courtesy of http://stackoverflow.com/a/31531797/4759433
    name = tlobject.name if isinstance(tlobject, TLObject) else tlobject
    result = re.sub(r'_([a-z])', lambda m: m.group(1).upper(), name)

    # Replace '_' with '' once again to make sure it doesn't appear on the name
    result = result[:1].upper() + result[1:].replace('_', '')

    # If it's a function, let it end with "Request" to identify them more easily
    if isinstance(tlobject, TLObject) and tlobject.is_function:
        result += 'Request'

    return result


# TLObject -> filename
def get_file_name(tlobject, add_extension=False):
    """Gets the file name in file_name_format.html for the given TLObject.
       Only its name may also be given if the full TLObject is not available"""
    if isinstance(tlobject, TLObject):
        name = tlobject.name
    else:
        name = tlobject

    # Courtesy of http://stackoverflow.com/a/1176023/4759433
    s1 = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', name)
    result = re.sub('([a-z0-9])([A-Z])', r'\1_\2', s1).lower()
    if add_extension:
        return result + '.html'
    else:
        return result


def get_create_path_for(tlobject):
    """Gets the file path (and creates the parent directories)
       for the given 'tlobject', relative to nothing; only its local path"""

    # Determine the output directory
    out_dir = 'methods' if tlobject.is_function else 'constructors'

    if tlobject.namespace:
        out_dir = os.path.join(out_dir, tlobject.namespace)

    # Ensure that it exists
    os.makedirs(out_dir, exist_ok=True)

    # Return the resulting filename
    return os.path.join(out_dir, get_file_name(tlobject, add_extension=True))


def get_path_for_type(type, relative_to='.'):
    """Similar to getting the path for a TLObject, it might not be possible
       to have the TLObject itself but rather its name (the type);
       this method works in the same way, returning a relative path"""
    if type.lower() in {'int', 'long', 'int128', 'int256', 'double',
                        'vector', 'string', 'bool', 'true', 'bytes', 'date'}:
        path = 'index.html#%s' % type.lower()

    elif '.' in type:
        # If it's not a core type, then it has to be a custom Telegram type
        namespace, name = type.split('.')
        path = 'types/%s/%s' % (namespace, get_file_name(name, add_extension=True))
    else:
        path = 'types/%s' % get_file_name(type, add_extension=True)

    return get_relative_path(path, relative_to)


# Destination path from the current position -> relative to the given path
def get_relative_path(destination, relative_to):
    if os.path.isfile(relative_to):
        relative_to = os.path.dirname(relative_to)

    return os.path.relpath(destination, start=relative_to)


def get_relative_paths(original, relative_to):
    """Converts the dictionary of 'original' paths to relative paths
       starting from the given 'relative_to' file"""
    return {k: get_relative_path(v, relative_to) for k, v in original.items()}


# Generate a index.html file for the given folder
def find_title(html_file):
    """Finds the <title> for the given HTML file, returns (Unknown) if not found"""
    with open(html_file) as handle:
        for line in handle:
            if '<title>' in line:
                # + 7 to skip len('<title>')
                return line[line.index('<title>') + 7:line.index('</title>')]

    return '(Unknown)'


def build_menu(docs, filename, relative_main_index):
    """Builds the menu using the given DocumentWriter up to 'filename',
       which must be a file (it cannot be a directory)"""
    # TODO Maybe this could be part of DocsWriter itself, "build path menu"
    docs.add_menu('API', relative_main_index)

    items = filename.split('/')
    for i in range(len(items) - 1):
        item = items[i]
        link = '../' * (len(items) - (i + 2))
        link += 'index.html'
        docs.add_menu(item.title(), link=link)

    if items[-1] != 'index.html':
        docs.add_menu(os.path.splitext(items[-1])[0])
    docs.end_menu()


def generate_index(folder, original_paths):
    """Generates the index file for the specified folder"""

    # Determine the namespaces listed here (as subfolders)
    # and the files (.html files) that we should link to
    namespaces = []
    files = []
    for item in os.listdir(folder):
        if os.path.isdir(os.path.join(folder, item)):
            namespaces.append(item)
        elif item != 'index.html':
            files.append(item)

    # We work with relative paths
    paths = get_relative_paths(original_paths, relative_to=folder)

    # Now that everything is setup, write the index.html file
    filename = os.path.join(folder, 'index.html')
    with DocsWriter(filename, type_to_path_function=get_path_for_type) as docs:
        # Title should be the current folder name
        docs.write_head(folder.title(), relative_css_path=paths['css'])

        docs.set_menu_separator(paths['arrow'])
        build_menu(docs, filename, relative_main_index=paths['index_all'])

        docs.write_title(folder.title())

        if namespaces:
            docs.write_title('Namespaces', level=3)
            docs.begin_table(4)
            for namespace in namespaces:
                # For every namespace, also write the index of it
                generate_index(os.path.join(folder, namespace), original_paths)
                docs.add_row(namespace.title(),
                             link=os.path.join(namespace, 'index.html'))

            docs.end_table()

        docs.write_title('Available items')
        docs.begin_table(2)
        for file in files:
            docs.add_row(find_title(os.path.join(folder, file)),
                         link=file)
        docs.end_table()
        docs.end_body()


def generate_documentation(scheme_file):
    """Generates the documentation HTML files from from scheme.tl to /methods and /constructors, etc."""
    original_paths = {
        'css': 'css/docs.css',
        'arrow': 'img/arrow.svg',
        'index_all': 'index.html',
        'index_types': 'types/index.html',
        'index_methods': 'methods/index.html',
        'index_constructors': 'constructors/index.html'
    }

    tlobjects = tuple(TLParser.parse_file(scheme_file))

    print('Generating constructors and functions documentation...')
    for tlobject in tlobjects:
        filename = get_create_path_for(tlobject)

        # Determine the relative paths for this file
        paths = get_relative_paths(original_paths, relative_to=filename)

        with DocsWriter(filename, type_to_path_function=get_path_for_type) as docs:
            docs.write_head(
                title=get_class_name(tlobject),
                relative_css_path=paths['css'])

            # Create the menu (path to the current TLObject)
            docs.set_menu_separator(paths['arrow'])
            build_menu(docs, filename, relative_main_index=paths['index_all'])

            # Create the page title
            docs.write_title(get_class_name(tlobject))

            # Write the code definition for this TLObject
            docs.write_code(tlobject)

            docs.write_title('Parameters' if tlobject.is_function else 'Members', level=3)

            # Sort the arguments in the same way they're sorted on the generated code (flags go last)
            args = sorted([a for a in tlobject.args if
                           not a.flag_indicator and not a.generic_definition],
                          key=lambda a: a.is_flag)
            if args:
                # Writing parameters
                docs.begin_table(column_count=3)

                for arg in args:
                    # Name row
                    docs.add_row(arg.name,
                                 bold=True)

                    # Type row
                    if arg.is_generic:
                        docs.add_row('!' + arg.type, align='center')
                    else:
                        docs.add_row(arg.type,
                                     link=get_path_for_type(arg.type, relative_to=filename),
                                     align='center')

                    # Create a description for this argument
                    description = ''
                    if arg.is_vector:
                        description += 'A list must be supplied for this argument. '
                    if arg.is_generic:
                        description += 'A different MTProtoRequest must be supplied for this argument. '
                    if arg.is_flag:
                        description += 'This argument can be omitted. '

                    docs.add_row(description.strip())

                docs.end_table()
            else:
                if tlobject.is_function:
                    docs.write_text('This request takes no input parameters.')
                else:
                    docs.write_text('This type has no members.')

            docs.end_body()

    # Find all the available types (which are not the same as the constructors)
    # Each type has a list of constructors associated to it, so it should be a map
    print('Generating types documentation...')
    tltypes = {}
    tlfunctions = {}
    for tlobject in tlobjects:
        # Select to which dictionary we want to store this type
        dictionary = tlfunctions if tlobject.is_function else tltypes

        if tlobject.result in dictionary:
            dictionary[tlobject.result].append(tlobject)
        else:
            dictionary[tlobject.result] = [tlobject]

    for tltype, constructors in tltypes.items():
        filename = get_path_for_type(tltype)
        out_dir = os.path.dirname(filename)
        os.makedirs(out_dir, exist_ok=True)

        # Since we don't have access to the full TLObject, split the type into namespace.name
        if '.' in tltype:
            namespace, name = tltype.split('.')
        else:
            namespace, name = None, tltype

        # Determine the relative paths for this file
        paths = get_relative_paths(original_paths, relative_to=out_dir)

        with DocsWriter(filename, type_to_path_function=get_path_for_type) as docs:
            docs.write_head(
                title=get_class_name(name),
                relative_css_path=paths['css'])

            docs.set_menu_separator(paths['arrow'])
            build_menu(docs, filename, relative_main_index=paths['index_all'])

            # Main file title
            docs.write_title(get_class_name(name))

            docs.write_title('Available constructors', level=3)
            if not constructors:
                docs.write_text('This type has no constructors available.')
            elif len(constructors) == 1:
                docs.write_text('This type has one constructor available.')
            else:
                docs.write_text('This type has %d constructors available.' % len(constructors))

            docs.begin_table(2)
            for constructor in constructors:
                # Constructor full name
                link = get_create_path_for(constructor)
                link = get_relative_path(link, relative_to=filename)
                docs.add_row(get_class_name(constructor), link=link)
            docs.end_table()

            docs.write_title('Methods returning this type', level=3)
            functions = tlfunctions.get(tltype, [])
            if not functions:
                docs.write_text('No method returns this type.')
            elif len(functions) == 1:
                docs.write_text('Only the following method returns this type.')
            else:
                docs.write_text('The following %d methods return this type as a result.' % len(functions))

            docs.begin_table(2)
            for function in functions:
                link = get_create_path_for(function)
                link = get_relative_path(link, relative_to=filename)
                docs.add_row(get_class_name(function), link=link)
            docs.end_table()
            docs.end_body()

    # After everything's been written, generate an index.html file for every folder.
    # This will be done automatically and not taking into account any additional
    # information that we have available, simply a file listing all the others
    # accessible by clicking on their title
    print('Generating indices...')
    for folder in ['types', 'methods', 'constructors']:
        generate_index(folder, original_paths)

    # Write the final core index, the main index for the rest of files
    layer = TLParser.find_layer(scheme_file)
    types = set()
    methods = []
    for tlobject in tlobjects:
        if tlobject.is_function:
            methods.append(tlobject)

        types.add(tlobject.result)

    types = sorted(types)
    methods = sorted(methods, key=lambda m: m.name)

    request_names = ', '.join('"' + get_class_name(m) + '"' for m in methods)
    type_names = ', '.join('"' + get_class_name(t) + '"' for t in types)

    request_urls = ', '.join('"' + get_create_path_for(m) + '"' for m in methods)
    type_urls = ', '.join('"' + get_path_for_type(t) + '"' for t in types)

    replace_dict = {
        'type_count': len(types),
        'method_count': len(methods),
        'constructor_count': len(tlobjects) - len(methods),
        'layer': layer,

        'request_names': request_names,
        'type_names': type_names,
        'request_urls': request_urls,
        'type_urls': type_urls
    }

    with open('../res/core.html') as infile:
        with open(original_paths['index_all'], 'w') as outfile:
            text = infile.read()
            for key, value in replace_dict.items():
                text = text.replace('{' + key + '}', str(value))

            outfile.write(text)

    # Everything done
    print('Documentation generated.')


def copy_resources():
    for d in ['css', 'img']:
        os.makedirs(d, exist_ok=True)

    shutil.copy('../res/img/arrow.svg', 'img')
    shutil.copy('../res/css/docs.css', 'css')


if __name__ == '__main__':
    os.makedirs('generated', exist_ok=True)
    os.chdir('generated')
    generate_documentation('../../telethon_generator/scheme.tl')
    copy_resources()