# coding=utf-8

import dateutil.parser
import logging
import os
import re
import uuid

from collections import OrderedDict
from fuzzywuzzy import fuzz

from django.conf import settings
try:
    from django.core.urlresolvers import reverse
except ImportError:
    from django.urls import reverse
from django.db import models
from django.template.defaultfilters import slugify
from django.utils import timezone

from .managers import LogManager


class MatchingModel(models.Model):

    MATCH_ANY = 1
    MATCH_ALL = 2
    MATCH_LITERAL = 3
    MATCH_REGEX = 4
    MATCH_FUZZY = 5
    MATCHING_ALGORITHMS = (
        (MATCH_ANY, "Any"),
        (MATCH_ALL, "All"),
        (MATCH_LITERAL, "Literal"),
        (MATCH_REGEX, "Regular Expression"),
        (MATCH_FUZZY, "Fuzzy Match"),
    )

    name = models.CharField(max_length=128, unique=True)
    slug = models.SlugField(blank=True)

    match = models.CharField(max_length=256, blank=True)
    matching_algorithm = models.PositiveIntegerField(
        choices=MATCHING_ALGORITHMS,
        default=MATCH_ANY,
        help_text=(
            "Which algorithm you want to use when matching text to the OCR'd "
            "PDF.  Here, \"any\" looks for any occurrence of any word "
            "provided in the PDF, while \"all\" requires that every word "
            "provided appear in the PDF, albeit not in the order provided.  A "
            "\"literal\" match means that the text you enter must appear in "
            "the PDF exactly as you've entered it, and \"regular expression\" "
            "uses a regex to match the PDF.  (If you don't know what a regex "
            "is, you probably don't want this option.)  Finally, a \"fuzzy "
            "match\" looks for words or phrases that are mostly—but not "
            "exactly—the same, which can be useful for matching against "
            "documents containg imperfections that foil accurate OCR."
        )
    )

    is_insensitive = models.BooleanField(default=True)

    class Meta:
        abstract = True
        ordering = ("name",)

    def __str__(self):
        return self.name

    @property
    def conditions(self):
        return "{}: \"{}\" ({})".format(
            self.name, self.match, self.get_matching_algorithm_display())

    @classmethod
    def match_all(cls, text, tags=None):

        if tags is None:
            tags = cls.objects.all()

        text = text.lower()
        for tag in tags:
            if tag.matches(text):
                yield tag

    def matches(self, text):

        search_kwargs = {}

        # Check that match is not empty
        if self.match.strip() == "":
            return False

        if self.is_insensitive:
            search_kwargs = {"flags": re.IGNORECASE}

        if self.matching_algorithm == self.MATCH_ALL:
            for word in self._split_match():
                search_result = re.search(
                    r"\b{}\b".format(word), text, **search_kwargs)
                if not search_result:
                    return False
            return True

        if self.matching_algorithm == self.MATCH_ANY:
            for word in self._split_match():
                if re.search(r"\b{}\b".format(word), text, **search_kwargs):
                    return True
            return False

        if self.matching_algorithm == self.MATCH_LITERAL:
            return bool(re.search(
                r"\b{}\b".format(self.match), text, **search_kwargs))

        if self.matching_algorithm == self.MATCH_REGEX:
            return bool(re.search(
                re.compile(self.match, **search_kwargs), text))

        if self.matching_algorithm == self.MATCH_FUZZY:
            match = re.sub(r'[^\w\s]', '', self.match)
            text = re.sub(r'[^\w\s]', '', text)
            if self.is_insensitive:
                match = match.lower()
                text = text.lower()

            return True if fuzz.partial_ratio(match, text) >= 90 else False

        raise NotImplementedError("Unsupported matching algorithm")

    def _split_match(self):
        """
        Splits the match to individual keywords, getting rid of unnecessary
        spaces and grouping quoted words together.

        Example:
          '  some random  words "with   quotes  " and   spaces'
            ==>
          ["some", "random", "words", "with+quotes", "and", "spaces"]
        """
        findterms = re.compile(r'"([^"]+)"|(\S+)').findall
        normspace = re.compile(r"\s+").sub
        return [
            normspace(" ", (t[0] or t[1]).strip()).replace(" ", r"\s+")
            for t in findterms(self.match)
        ]

    def save(self, *args, **kwargs):

        self.match = self.match.lower()

        if not self.slug:
            self.slug = slugify(self.name)

        models.Model.save(self, *args, **kwargs)


class Correspondent(MatchingModel):

    # This regex is probably more restrictive than it needs to be, but it's
    # better safe than sorry.
    SAFE_REGEX = re.compile(r"^[\w\- ,.']+$")

    class Meta:
        ordering = ("name",)


class Tag(MatchingModel):

    COLOURS = (
        (1, "#a6cee3"),
        (2, "#1f78b4"),
        (3, "#b2df8a"),
        (4, "#33a02c"),
        (5, "#fb9a99"),
        (6, "#e31a1c"),
        (7, "#fdbf6f"),
        (8, "#ff7f00"),
        (9, "#cab2d6"),
        (10, "#6a3d9a"),
        (11, "#b15928"),
        (12, "#000000"),
        (13, "#cccccc")
    )

    colour = models.PositiveIntegerField(choices=COLOURS, default=1)


class Document(models.Model):

    TYPE_PDF = "pdf"
    TYPE_PNG = "png"
    TYPE_JPG = "jpg"
    TYPE_GIF = "gif"
    TYPE_TIF = "tiff"
    TYPE_TXT = "txt"
    TYPE_CSV = "csv"
    TYPE_MD  = "md"
    TYPES = (TYPE_PDF, TYPE_PNG, TYPE_JPG, TYPE_GIF, TYPE_TIF,
             TYPE_TXT, TYPE_CSV, TYPE_MD)

    STORAGE_TYPE_UNENCRYPTED = "unencrypted"
    STORAGE_TYPE_GPG = "gpg"
    STORAGE_TYPES = (
        (STORAGE_TYPE_UNENCRYPTED, "Unencrypted"),
        (STORAGE_TYPE_GPG, "Encrypted with GNU Privacy Guard")
    )

    correspondent = models.ForeignKey(
        Correspondent,
        blank=True,
        null=True,
        related_name="documents",
        on_delete=models.SET_NULL
    )

    title = models.CharField(max_length=128, blank=True, db_index=True)

    content = models.TextField(
        db_index=True,
        blank=True,
        help_text="The raw, text-only data of the document.  This field is "
                  "primarily used for searching."
    )

    file_type = models.CharField(
        max_length=4,
        editable=False,
        choices=tuple([(t, t.upper()) for t in TYPES])
    )

    tags = models.ManyToManyField(
        Tag, related_name="documents", blank=True)

    checksum = models.CharField(
        max_length=32,
        editable=False,
        unique=True,
        help_text="The checksum of the original document (before it was "
                  "encrypted).  We use this to prevent duplicate document "
                  "imports."
    )

    created = models.DateTimeField(
        default=timezone.now, db_index=True)
    modified = models.DateTimeField(
        auto_now=True, editable=False, db_index=True)

    storage_type = models.CharField(
        max_length=11,
        choices=STORAGE_TYPES,
        default=STORAGE_TYPE_UNENCRYPTED,
        editable=False
    )

    added = models.DateTimeField(
        default=timezone.now, editable=False, db_index=True)

    class Meta:
        ordering = ("correspondent", "title")

    def __str__(self):
        created = self.created.strftime("%Y%m%d%H%M%S")
        if self.correspondent and self.title:
            return "{}: {} - {}".format(
                created, self.correspondent, self.title)
        if self.correspondent or self.title:
            return "{}: {}".format(created, self.correspondent or self.title)
        return str(created)

    @property
    def source_path(self):

        file_name = "{:07}.{}".format(self.pk, self.file_type)
        if self.storage_type == self.STORAGE_TYPE_GPG:
            file_name += ".gpg"

        return os.path.join(
            settings.MEDIA_ROOT,
            "documents",
            "originals",
            file_name
        )

    @property
    def source_file(self):
        return open(self.source_path, "rb")

    @property
    def file_name(self):
        return slugify(str(self)) + "." + self.file_type

    @property
    def download_url(self):
        return reverse("fetch", kwargs={"kind": "doc", "pk": self.pk})

    @property
    def thumbnail_path(self):

        file_name = "{:07}.png".format(self.pk)
        if self.storage_type == self.STORAGE_TYPE_GPG:
            file_name += ".gpg"

        return os.path.join(
            settings.MEDIA_ROOT,
            "documents",
            "thumbnails",
            file_name
        )

    @property
    def thumbnail_file(self):
        return open(self.thumbnail_path, "rb")

    @property
    def thumbnail_url(self):
        return reverse("fetch", kwargs={"kind": "thumb", "pk": self.pk})


class Log(models.Model):

    LEVELS = (
        (logging.DEBUG, "Debugging"),
        (logging.INFO, "Informational"),
        (logging.WARNING, "Warning"),
        (logging.ERROR, "Error"),
        (logging.CRITICAL, "Critical"),
    )

    group = models.UUIDField(blank=True)
    message = models.TextField()
    level = models.PositiveIntegerField(choices=LEVELS, default=logging.INFO)
    created = models.DateTimeField(auto_now_add=True)
    modified = models.DateTimeField(auto_now=True)

    objects = LogManager()

    class Meta:
        ordering = ("-modified",)

    def __str__(self):
        return self.message

    def save(self, *args, **kwargs):
        """
        To allow for the case where we don't want to group the message, we
        shouldn't force the caller to specify a one-time group value.  However,
        allowing group=None means that the manager can't differentiate the
        different un-grouped messages, so instead we set a random one here.
        """

        if not self.group:
            self.group = uuid.uuid4()

        models.Model.save(self, *args, **kwargs)


class FileInfo:

    # This epic regex *almost* worked for our needs, so I'm keeping it here for
    # posterity, in the hopes that we might find a way to make it work one day.
    ALMOST_REGEX = re.compile(
        r"^((?P<date>\d\d\d\d\d\d\d\d\d\d\d\d\d\dZ){separator})?"
        r"((?P<correspondent>{non_separated_word}+){separator})??"
        r"(?P<title>{non_separated_word}+)"
        r"({separator}(?P<tags>[a-z,0-9-]+))?"
        r"\.(?P<extension>[a-zA-Z.-]+)$".format(
            separator=r"\s+-\s+",
            non_separated_word=r"([\w,. ]|([^\s]-))"
        )
    )

    formats = "pdf|jpe?g|png|gif|tiff?|te?xt|md|csv"
    REGEXES = OrderedDict([
        ("created-correspondent-title-tags", re.compile(
            r"^(?P<created>\d\d\d\d\d\d\d\d(\d\d\d\d\d\d)?Z) - "
            r"(?P<correspondent>.*) - "
            r"(?P<title>.*) - "
            r"(?P<tags>[a-z0-9\-,]*)"
            r"\.(?P<extension>{})$".format(formats),
            flags=re.IGNORECASE
        )),
        ("created-title-tags", re.compile(
            r"^(?P<created>\d\d\d\d\d\d\d\d(\d\d\d\d\d\d)?Z) - "
            r"(?P<title>.*) - "
            r"(?P<tags>[a-z0-9\-,]*)"
            r"\.(?P<extension>{})$".format(formats),
            flags=re.IGNORECASE
        )),
        ("created-correspondent-title", re.compile(
            r"^(?P<created>\d\d\d\d\d\d\d\d(\d\d\d\d\d\d)?Z) - "
            r"(?P<correspondent>.*) - "
            r"(?P<title>.*)"
            r"\.(?P<extension>{})$".format(formats),
            flags=re.IGNORECASE
        )),
        ("created-title", re.compile(
            r"^(?P<created>\d\d\d\d\d\d\d\d(\d\d\d\d\d\d)?Z) - "
            r"(?P<title>.*)"
            r"\.(?P<extension>{})$".format(formats),
            flags=re.IGNORECASE
        )),
        ("correspondent-title-tags", re.compile(
            r"(?P<correspondent>.*) - "
            r"(?P<title>.*) - "
            r"(?P<tags>[a-z0-9\-,]*)"
            r"\.(?P<extension>{})$".format(formats),
            flags=re.IGNORECASE
        )),
        ("correspondent-title", re.compile(
            r"(?P<correspondent>.*) - "
            r"(?P<title>.*)?"
            r"\.(?P<extension>{})$".format(formats),
            flags=re.IGNORECASE
        )),
        ("title", re.compile(
            r"(?P<title>.*)"
            r"\.(?P<extension>{})$".format(formats),
            flags=re.IGNORECASE
        ))
    ])

    def __init__(self, created=None, correspondent=None, title=None, tags=(),
                 extension=None):

        self.created = created
        self.title = title
        self.extension = extension
        self.correspondent = correspondent
        self.tags = tags

    @classmethod
    def _get_created(cls, created):
        try:
            return dateutil.parser.parse("{:0<14}Z".format(created[:-1]))
        except ValueError:
            return None

    @classmethod
    def _get_correspondent(cls, name):
        if not name:
            return None
        return Correspondent.objects.get_or_create(name=name, defaults={
            "slug": slugify(name)
        })[0]

    @classmethod
    def _get_title(cls, title):
        return title

    @classmethod
    def _get_tags(cls, tags):
        r = []
        for t in tags.split(","):
            r.append(Tag.objects.get_or_create(
                slug=t.lower(),
                defaults={"name": t}
            )[0])
        return tuple(r)

    @classmethod
    def _get_extension(cls, extension):
        r = extension.lower()
        if r == "jpeg":
            return "jpg"
        if r == "tif":
            return "tiff"
        return r

    @classmethod
    def _mangle_property(cls, properties, name):
        if name in properties:
            properties[name] = getattr(cls, "_get_{}".format(name))(
                properties[name]
            )

    @classmethod
    def from_path(cls, path):
        """
        We use a crude naming convention to make handling the correspondent,
        title, and tags easier:
          "<date> - <correspondent> - <title> - <tags>.<suffix>"
          "<correspondent> - <title> - <tags>.<suffix>"
          "<correspondent> - <title>.<suffix>"
          "<title>.<suffix>"
        """

        for regex in cls.REGEXES.values():
            m = regex.match(os.path.basename(path))
            if m:
                properties = m.groupdict()
                cls._mangle_property(properties, "created")
                cls._mangle_property(properties, "correspondent")
                cls._mangle_property(properties, "title")
                cls._mangle_property(properties, "tags")
                cls._mangle_property(properties, "extension")
                return cls(**properties)