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

from collections import OrderedDict
from fuzzywuzzy import fuzz

from django.conf import settings
from django.core.urlresolvers 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(object):
        abstract = True

    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.match.split(" "):
                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.match.split(" "):
                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 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(object):
        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"
    TYPES = (TYPE_PDF, TYPE_PNG, TYPE_JPG, TYPE_GIF, TYPE_TIF,)

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

    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)

    class Meta(object):
        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):
        return os.path.join(
            settings.MEDIA_ROOT,
            "documents",
            "originals",
            "{:07}.{}.gpg".format(self.pk, self.file_type)
        )

    @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):
        return os.path.join(
            settings.MEDIA_ROOT,
            "documents",
            "thumbnails",
            "{:07}.png.gpg".format(self.pk)
        )

    @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(object):
        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(object):

    # 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]-))"
        )
    )

    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>pdf|jpe?g|png|gif|tiff)$",
            flags=re.IGNORECASE
        )),
        ("created-title-tags", re.compile(
            r"^(?P<created>\d\d\d\d\d\d\d\d(\d\d\d\d\d\d)?Z) - "
            r"(?P<title>.*) - "
            r"(?P<tags>[a-z0-9\-,]*)"
            r"\.(?P<extension>pdf|jpe?g|png|gif|tiff)$",
            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>pdf|jpe?g|png|gif|tiff)$",
            flags=re.IGNORECASE
        )),
        ("created-title", re.compile(
            r"^(?P<created>\d\d\d\d\d\d\d\d(\d\d\d\d\d\d)?Z) - "
            r"(?P<title>.*)"
            r"\.(?P<extension>pdf|jpe?g|png|gif|tiff)$",
            flags=re.IGNORECASE
        )),
        ("correspondent-title-tags", re.compile(
            r"(?P<correspondent>.*) - "
            r"(?P<title>.*) - "
            r"(?P<tags>[a-z0-9\-,]*)"
            r"\.(?P<extension>pdf|jpe?g|png|gif|tiff)$",
            flags=re.IGNORECASE
        )),
        ("correspondent-title", re.compile(
            r"(?P<correspondent>.*) - "
            r"(?P<title>.*)?"
            r"\.(?P<extension>pdf|jpe?g|png|gif|tiff)$",
            flags=re.IGNORECASE
        )),
        ("title", re.compile(
            r"(?P<title>.*)"
            r"\.(?P<extension>pdf|jpe?g|png|gif|tiff)$",
            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):
        return dateutil.parser.parse("{:0<14}Z".format(created[:-1]))

    @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, defaults={"name": t})[0])
        return tuple(r)

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