# -*- coding: utf-8 -*-

# Copyright 2017-2018 Mike Fährmann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.

"""Utility functions and classes"""

import re
import os
import sys
import shutil
import string
import _string
import sqlite3
import datetime
import operator
import itertools
import urllib.parse
from . import text, exception


def bencode(num, alphabet="0123456789"):
    """Encode an integer into a base-N encoded string"""
    data = ""
    base = len(alphabet)
    while num:
        num, remainder = divmod(num, base)
        data = alphabet[remainder] + data
    return data


def bdecode(data, alphabet="0123456789"):
    """Decode a base-N encoded string ( N = len(alphabet) )"""
    num = 0
    base = len(alphabet)
    for c in data:
        num *= base
        num += alphabet.index(c)
    return num


def advance(iterable, num):
    """"Advance the iterable by 'num' steps"""
    iterator = iter(iterable)
    next(itertools.islice(iterator, num, num), None)
    return iterator


def raises(obj):
    """Returns a function that raises 'obj' as exception"""
    def wrap():
        raise obj
    return wrap


def combine_dict(a, b):
    """Recursively combine the contents of 'b' into 'a'"""
    for key, value in b.items():
        if key in a and isinstance(value, dict) and isinstance(a[key], dict):
            combine_dict(a[key], value)
        else:
            a[key] = value
    return a


def transform_dict(a, func):
    """Recursively apply 'func' to all values in 'a'"""
    for key, value in a.items():
        if isinstance(value, dict):
            transform_dict(value, func)
        else:
            a[key] = func(value)


def number_to_string(value):
    """Convert numbers (int, float) to string; Return everything else as is."""
    return str(value) if isinstance(value, (int, float)) else value


def expand_path(path):
    """Expand environment variables and tildes (~)"""
    if not path:
        return path
    if not isinstance(path, str):
        path = os.path.join(*path)
    return os.path.expandvars(os.path.expanduser(path))


def code_to_language(code, default=None):
    """Map an ISO 639-1 language code to its actual name"""
    return CODES.get((code or "").lower(), default)


def language_to_code(lang, default=None):
    """Map a language name to its ISO 639-1 code"""
    if lang is None:
        return default
    lang = lang.capitalize()
    for code, language in CODES.items():
        if language == lang:
            return code
    return default


CODES = {
    "ar": "Arabic",
    "bg": "Bulgarian",
    "ca": "Catalan",
    "cs": "Czech",
    "da": "Danish",
    "de": "German",
    "el": "Greek",
    "en": "English",
    "es": "Spanish",
    "fi": "Finnish",
    "fr": "French",
    "he": "Hebrew",
    "hu": "Hungarian",
    "id": "Indonesian",
    "it": "Italian",
    "jp": "Japanese",
    "ko": "Korean",
    "ms": "Malay",
    "nl": "Dutch",
    "no": "Norwegian",
    "pl": "Polish",
    "pt": "Portuguese",
    "ro": "Romanian",
    "ru": "Russian",
    "sv": "Swedish",
    "th": "Thai",
    "tr": "Turkish",
    "vi": "Vietnamese",
    "zh": "Chinese",
}

SPECIAL_EXTRACTORS = {"oauth", "recursive", "test"}


def build_predicate(predicates):
    if not predicates:
        return lambda url, kwds: True
    elif len(predicates) == 1:
        return predicates[0]
    else:
        return ChainPredicate(predicates)


class RangePredicate():
    """Predicate; True if the current index is in the given range"""
    def __init__(self, rangespec):
        self.ranges = self.optimize_range(self.parse_range(rangespec))
        self.index = 0

        if self.ranges:
            self.lower, self.upper = self.ranges[0][0], self.ranges[-1][1]
        else:
            self.lower, self.upper = 0, 0

    def __call__(self, url, kwds):
        self.index += 1

        if self.index > self.upper:
            raise exception.StopExtraction()

        for lower, upper in self.ranges:
            if lower <= self.index <= upper:
                return True
        return False

    @staticmethod
    def parse_range(rangespec):
        """Parse an integer range string and return the resulting ranges

        Examples:
            parse_range("-2,4,6-8,10-") -> [(1,2), (4,4), (6,8), (10,INTMAX)]
            parse_range(" - 3 , 4-  4, 2-6") -> [(1,3), (4,4), (2,6)]
        """
        ranges = []

        for group in rangespec.split(","):
            if not group:
                continue
            first, sep, last = group.partition("-")
            if not sep:
                beg = end = int(first)
            else:
                beg = int(first) if first.strip() else 1
                end = int(last) if last.strip() else sys.maxsize
            ranges.append((beg, end) if beg <= end else (end, beg))

        return ranges

    @staticmethod
    def optimize_range(ranges):
        """Simplify/Combine a parsed list of ranges

        Examples:
            optimize_range([(2,4), (4,6), (5,8)]) -> [(2,8)]
            optimize_range([(1,1), (2,2), (3,6), (8,9))]) -> [(1,6), (8,9)]
        """
        if len(ranges) <= 1:
            return ranges

        ranges.sort()
        riter = iter(ranges)
        result = []

        beg, end = next(riter)
        for lower, upper in riter:
            if lower > end+1:
                result.append((beg, end))
                beg, end = lower, upper
            elif upper > end:
                end = upper
        result.append((beg, end))
        return result


class UniquePredicate():
    """Predicate; True if given URL has not been encountered before"""
    def __init__(self):
        self.urls = set()

    def __call__(self, url, kwds):
        if url.startswith("text:"):
            return True
        if url not in self.urls:
            self.urls.add(url)
            return True
        return False


class FilterPredicate():
    """Predicate; True if evaluating the given expression returns True"""
    globalsdict = {
        "parse_int": text.parse_int,
        "urlsplit": urllib.parse.urlsplit,
        "datetime": datetime.datetime,
        "abort": raises(exception.StopExtraction()),
        "re": re,
    }

    def __init__(self, filterexpr, target="image"):
        name = "<{} filter>".format(target)
        self.codeobj = compile(filterexpr, name, "eval")

    def __call__(self, url, kwds):
        try:
            return eval(self.codeobj, self.globalsdict, kwds)
        except exception.GalleryDLException:
            raise
        except Exception as exc:
            raise exception.FilterError(exc)


class ChainPredicate():
    """Predicate; True if all of its predicates return True"""
    def __init__(self, predicates):
        self.predicates = predicates

    def __call__(self, url, kwds):
        for pred in self.predicates:
            if not pred(url, kwds):
                return False
        return True


class ExtendedUrl():
    """URL with attached config key-value pairs"""
    def __init__(self, url, gconf, lconf):
        self.value, self.gconfig, self.lconfig = url, gconf, lconf

    def __str__(self):
        return self.value


class Formatter():
    """Custom, extended version of string.Formatter

    This string formatter implementation is a mostly performance-optimized
    variant of the original string.Formatter class. Unnecessary features have
    been removed (positional arguments, unused argument check) and new
    formatting options have been added.

    Extra Conversions:
    - "l": calls str.lower on the target value
    - "u": calls str.upper
    - "c": calls str.capitalize
    - "C": calls string.capwords
    - "U": calls urllib.parse.unquote
    - Example: {f!l} -> "example"; {f!u} -> "EXAMPLE"

    Extra Format Specifiers:
    - "?<before>/<after>/":
        Adds <before> and <after> to the actual value if it evaluates to True.
        Otherwise the whole replacement field becomes an empty string.
        Example: {f:?-+/+-/} -> "-+Example+-" (if "f" contains "Example")
                             -> ""            (if "f" is None, 0, "")

    - "L<maxlen>/<replacement>/":
        Replaces the output with <replacement> if its length (in characters)
        exceeds <maxlen>. Otherwise everything is left as is.
        Example: {f:L5/too long/} -> "foo"      (if "f" is "foo")
                                  -> "too long" (if "f" is "foobar")
    """
    conversions = {
        "l": str.lower,
        "u": str.upper,
        "c": str.capitalize,
        "C": string.capwords,
        "U": urllib.parse.unquote,
        "s": str,
        "r": repr,
        "a": ascii,
    }

    def __init__(self, format_string, default=None):
        self.default = default
        self.result = []
        self.fields = []

        for literal_text, field_name, format_spec, conversion in \
                _string.formatter_parser(format_string):
            if literal_text:
                self.result.append(literal_text)
            if field_name:
                self.fields.append((
                    len(self.result),
                    self._field_access(field_name, format_spec, conversion)
                ))
                self.result.append("")

    def format_map(self, kwargs):
        """Apply 'kwargs' to the initial format_string and return its result"""
        for index, func in self.fields:
            self.result[index] = func(kwargs)
        return "".join(self.result)

    def _field_access(self, field_name, format_spec, conversion):
        first, rest = _string.formatter_field_name_split(field_name)

        funcs = []
        for is_attr, key in rest:
            if is_attr:
                func = operator.attrgetter
            elif ":" in key:
                func = self._slicegetter
            else:
                func = operator.itemgetter
            funcs.append(func(key))

        if conversion:
            funcs.append(self.conversions[conversion])

        if format_spec:
            if format_spec[0] == "?":
                func = self._format_optional
            elif format_spec[0] == "L":
                func = self._format_maxlen
            else:
                func = self._format_default
            fmt = func(format_spec)
        else:
            fmt = str

        if funcs:
            return self._apply(first, funcs, fmt)
        return self._apply_simple(first, fmt)

    def _apply_simple(self, key, fmt):
        def wrap(obj):
            if key in obj:
                obj = obj[key]
            else:
                obj = self.default
            return fmt(obj)
        return wrap

    def _apply(self, key, funcs, fmt):
        def wrap(obj):
            if key in obj:
                obj = obj[key]
                for func in funcs:
                    obj = func(obj)
            else:
                obj = self.default
            return fmt(obj)
        return wrap

    @staticmethod
    def _slicegetter(key):
        start, _, stop = key.partition(":")
        stop, _, step = stop.partition(":")
        start = int(start) if start else None
        stop = int(stop) if stop else None
        step = int(step) if step else None
        return operator.itemgetter(slice(start, stop, step))

    @staticmethod
    def _format_optional(format_spec):
        def wrap(obj):
            if not obj:
                return ""
            return before + format(obj, format_spec) + after
        before, after, format_spec = format_spec.split("/", 2)
        before = before[1:]
        return wrap

    @staticmethod
    def _format_maxlen(format_spec):
        def wrap(obj):
            obj = format(obj, format_spec)
            return obj if len(obj) <= maxlen else replacement
        maxlen, replacement, format_spec = format_spec.split("/", 2)
        maxlen = text.parse_int(maxlen[1:])
        return wrap

    @staticmethod
    def _format_default(format_spec):
        def wrap(obj):
            return format(obj, format_spec)
        return wrap


class PathFormat():

    def __init__(self, extractor):
        self.filename_fmt = extractor.config(
            "filename", extractor.filename_fmt)
        self.directory_fmt = extractor.config(
            "directory", extractor.directory_fmt)
        self.kwdefault = extractor.config("keywords-default")

        try:
            self.formatter = Formatter(self.filename_fmt, self.kwdefault)
        except Exception as exc:
            raise exception.FormatError(exc, "filename")

        self.delete = False
        self.has_extension = False
        self.keywords = {}
        self.filename = ""
        self.directory = self.realdirectory = ""
        self.path = self.realpath = self.temppath = ""

        self.basedirectory = expand_path(
            extractor.config("base-directory", (".", "gallery-dl")))
        if os.altsep:
            self.basedirectory = self.basedirectory.replace(os.altsep, os.sep)

    def open(self, mode="wb"):
        """Open file and return a corresponding file object"""
        return open(self.temppath, mode)

    def exists(self, archive=None):
        """Return True if the file exists on disk or in 'archive'"""
        if (archive and archive.check(self.keywords) or
                self.has_extension and os.path.exists(self.realpath)):
            if not self.has_extension:
                # adjust display name
                self.set_extension("")
                if self.path[-1] == ".":
                    self.path = self.path[:-1]
            return True
        return False

    def set_directory(self, keywords):
        """Build directory path and create it if necessary"""
        try:
            segments = [
                text.clean_path(
                    Formatter(segment, self.kwdefault)
                    .format_map(keywords).strip())
                for segment in self.directory_fmt
            ]
        except Exception as exc:
            raise exception.FormatError(exc, "directory")

        self.directory = os.path.join(
            self.basedirectory,
            *segments
        )

        # remove trailing path separator;
        # occurs if the last argument to os.path.join() is an empty string
        if self.directory[-1] == os.sep:
            self.directory = self.directory[:-1]

        self.realdirectory = self.adjust_path(self.directory)
        os.makedirs(self.realdirectory, exist_ok=True)

    def set_keywords(self, keywords):
        """Set filename keywords"""
        self.keywords = keywords
        self.temppath = ""
        self.has_extension = bool(keywords.get("extension"))
        if self.has_extension:
            self.build_path()

    def set_extension(self, extension, real=True):
        """Set the 'extension' keyword"""
        self.has_extension = real
        self.keywords["extension"] = extension
        self.build_path()

    def build_path(self):
        """Use filename-keywords and directory to build a full path"""
        try:
            self.filename = text.clean_path(
                self.formatter.format_map(self.keywords))
        except Exception as exc:
            raise exception.FormatError(exc, "filename")

        filename = os.sep + self.filename
        self.path = self.directory + filename
        self.realpath = self.realdirectory + filename
        if not self.temppath:
            self.temppath = self.realpath

    def part_enable(self, part_directory=None):
        """Enable .part file usage"""
        if self.has_extension:
            self.temppath += ".part"
        else:
            self.set_extension("part", False)
        if part_directory:
            self.temppath = os.path.join(
                part_directory,
                os.path.basename(self.temppath),
            )

    def part_size(self):
        """Return size of .part file"""
        try:
            return os.stat(self.temppath).st_size
        except OSError:
            pass
        return 0

    def finalize(self):
        """Move tempfile to its target location"""
        if self.delete:
            self.delete = False
            os.unlink(self.temppath)
            return

        if self.temppath == self.realpath:
            return

        try:
            os.replace(self.temppath, self.realpath)
            return
        except OSError:
            pass

        shutil.copyfile(self.temppath, self.realpath)
        os.unlink(self.temppath)

    @staticmethod
    def adjust_path(path):
        """Enable longer-than-260-character paths on windows"""
        return "\\\\?\\" + os.path.abspath(path) if os.name == "nt" else path


class DownloadArchive():

    def __init__(self, path, extractor):
        con = sqlite3.connect(path)
        con.isolation_level = None
        self.cursor = con.cursor()
        self.cursor.execute("CREATE TABLE IF NOT EXISTS archive "
                            "(entry PRIMARY KEY) WITHOUT ROWID")
        self.keygen = (extractor.category + extractor.config(
            "archive-format", extractor.archive_fmt)
        ).format_map

    def check(self, kwdict):
        """Return True if item described by 'kwdict' exists in archive"""
        key = self.keygen(kwdict)
        self.cursor.execute(
            "SELECT 1 FROM archive WHERE entry=? LIMIT 1", (key,))
        return self.cursor.fetchone()

    def add(self, kwdict):
        """Add item described by 'kwdict' to archive"""
        key = self.keygen(kwdict)
        self.cursor.execute(
            "INSERT OR IGNORE INTO archive VALUES (?)", (key,))