from os import SCHED_OTHER
from django.conf import settings
from django.shortcuts import resolve_url
from django.db import models
from django.utils.text import slugify
from django.utils.timezone import now
from django.utils.functional import cached_property
from django.core.files.storage import get_storage_class
from django.db.models import Q, Count, Min, Max

import re

from byostorage.user import BYOStorage
from byostorage.cached import CachedStorage

from library.music_tags import MusicTag
from interface.utils import sign_data

import logging

#from polyphonic.settings import LIBRARY_STORAGE
logger = logging.getLogger(__name__)

#try:
#    library_storage = get_storage_class(settings.LIBRARY_STORAGE)()
#except (ImportError, AttributeError):
#    logger.exception("Failed to load library storage")
#    library_storage = get_storage_class()()
#logger.info("Library storage: %s", library_storage.__class__.__name__)

# FIXME: move back to settings
library_storage = CachedStorage(BYOStorage())

class Orchestration(models.Model):
    """
    Stores a list of instrument codes as a single entry (space delimited).
    Can be global or ensemble specific
    """
    # TODO: change ensemble to collection
    #ensemble = models.ForeignKey('interface.Ensemble', on_delete=models.CASCADE, related_name="orchestrations", null=True, blank=True)
    collection = models.ForeignKey('Collection', on_delete=models.CASCADE, related_name="custom_orchestrations", null=True, blank=True)
    name = models.CharField(max_length=100)
    instruments = models.TextField()

    def as_list(self):
        tags = [ t.strip() for t in self.instruments.split(' ') ]
        return [ (t, MusicTag.from_tag(t)) for t in tags if t ]
    
    def tag_order(self):
        tags = [ t.strip() for t in self.instruments.split(' ') if t ]
        order = {'score': 0}
        for i, t in enumerate(tags):
            order.setdefault(t.strip('-0123456789'), i*2+1)
            
        return order

    def sorter(self):
        tag_order = self.tag_order()
        def f(x):
            return (tag_order.get(x[0].strip('-0123456789'), 1000), x[0])
        return f

    def save(self):
        self.as_list()
        super(Orchestration, self).save()

    def __str__(self):
        return self.name

class ProjectItem(models.Model):
    """
    ProjectItem represents a Work attached to a Project e.g. item in set list or programme
    It also allows works to be shared from one ensemble to another on a per-project basis.
    """
    project = models.ForeignKey('interface.Project', on_delete=models.CASCADE, related_name='items')
    work = models.ForeignKey('Work', on_delete=models.CASCADE, related_name='project_items')
    checkout = models.DateTimeField()
    due = models.DateTimeField(null=True, blank=True)
    returned = models.DateTimeField(null=True, blank=True)
    approved_by = models.ForeignKey('auth.User', on_delete=models.CASCADE)
    order = models.SmallIntegerField(default=0)
    section = models.CharField(max_length=100, blank=True)
    

    class Meta:
        ordering = ['order', 'work']

    def __str__(self):
        return f"<{self.project_id}:{slugify(self.work.name)}>"

class Collection(models.Model):
    """
    A logical collection of works, typically owned by an organisation or person (physical or virtual)
    """
    name = models.CharField(max_length=255,
            help_text="Name of the collection")
    prefix = models.SlugField(max_length=30, default="default",
            help_text="Folder to store works in")
    administrators = models.ManyToManyField('auth.User', related_name="collections", 
            help_text="Administrators for this collection")
    location = models.CharField(max_length=100, 
            help_text="Physical location (institution, town...)", blank=True)
    storage = models.ForeignKey('byostorage.UserStorage', on_delete=models.CASCADE, null=True, blank=True, 
            help_text="User storage for documents")
    notes = models.TextField(blank=True, 
            help_text="Publicly visible notes about collection and loans policy (markdown format)")
    nonce = models.SmallIntegerField(default=1,
            help_text="Increment this to reset the authentication links")

    def meta(self, name):
        items = WorkMeta.objects.filter(work__collection=self.pk, name=name).values_list('value', flat=True).distinct()
        return items

    @property
    def tags(self):
        return self.meta('tag')

    @property
    def genres(self):
        return self.meta('genre')    
    
    def has_administrator(self, user):
        if not user.is_authenticated:
            return False
        if user.is_superuser:
            return True
        return user.pk in self.administrators.values_list('pk', flat=True)

    def get_absolute_url(self):
        return resolve_url('collection_work_list', self.pk)

    def auth(self):
        return sign_data(f'{self.pk}-{self.nonce}', 12)
    
    def __str__(self):
        return self.name

class EnsembleAccess(models.Model):
    """
    Can have different access levels to a collection
    """

    ACCESS_UNLIMITED = 1
    ACCESS_APPROVED = 2

    ACCESS_TYPES = (
        (ACCESS_UNLIMITED, 'Unlimited'),
        (ACCESS_APPROVED, 'Approval required'),
    )

    ensemble = models.ForeignKey('interface.Ensemble', on_delete=models.CASCADE, related_name="allowed_collections")
    collection = models.ForeignKey(Collection, on_delete=models.CASCADE, related_name="allowed_ensembles")
    access_type = models.PositiveSmallIntegerField(choices=ACCESS_TYPES, default=2)

    class Meta:
        verbose_name_plural = "Ensemble access"


class Work(models.Model):
    """
    A musical work 'owned' by a collection from a licencing perspective.
    """
    LICENCE_PUBLIC = 2
    LICENCE_EXPIRED = 4
    LICENCE_RECORDING = 5
    LICENCE_PERFORMANCE = 6
    LICENCE_PERUSAL = 8
    LICENCE_NONE = 10

    LICENCE_TYPES = (
        (LICENCE_PUBLIC, 'Public Domain'),
        (LICENCE_EXPIRED, 'Copyright Expired'),
        (LICENCE_RECORDING, 'Recording Licence'),
        (LICENCE_PERFORMANCE, 'Performance Licence'),
        (LICENCE_PERUSAL, 'Perusal Licence'),
        (LICENCE_NONE, 'Internal use only'),
    )
    
    name = models.CharField(max_length=255, help_text="Original name of the work")
    edition = models.CharField(max_length=255, blank=True,
            help_text="Edition details to distinguish multiple versions")
    parent = models.ForeignKey('Work', null=True, blank=True, on_delete=models.SET_NULL, related_name="related_works",
            help_text="Arrangement of another work or part of an anthology")
    composer = models.CharField(max_length=255, default='Anon',
            help_text="Composer or compilation editor. Use <b>Surname, Initial</b> for easy searching")

    orchestration = models.ForeignKey(Orchestration, on_delete=models.SET_DEFAULT, default=1, help_text="Orchestration for the work")
    original_parts = models.JSONField(default=dict, blank=True, help_text="Original printed parts (IMSLP format)")

    # Collection details
    collection = models.ForeignKey(Collection, on_delete=models.CASCADE, related_name="works")
    code = models.CharField(max_length=100, blank=True, help_text="Collection specific code or number. Will be auto-generated if not supplied")
    licence = models.PositiveSmallIntegerField(choices=LICENCE_TYPES, default=6, help_text="Copyright status")
    max_projects = models.IntegerField(default=1, help_text="How many active projects can this work be attached to")
    
    # Extra info
    running_time = models.DurationField(null=True, blank=True, help_text="Running time in mm:ss format")
    notes = models.TextField(blank=True)

    # Allocation to projects 
    projects = models.ManyToManyField('interface.Project', through='ProjectItem', related_name="works", help_text="Current usage")

    @property
    def folder(self):
        return f"{slugify(self.composer)}/{slugify(self.name)}-{self.pk:04d}"

    def extract(self, *tags):

        qs = self.docs.filter(sections__tag__in=tags)
        qs = qs.annotate(Count('sections'), end=Min('sections__end'), start=Max('sections__start')) \
            .filter(sections__count=len(tags))
        
        return list(qs.values_list('upload', 'start', 'end'))

    @property
    def digital_parts(self):
        sections = [ (s.tag, s) for s in Section.objects.filter(doc__work=self.pk) ]
        sections.sort(key=self.orchestration.sorter())
        return [ s[1] for s in sections ]

    @property
    def physical_parts(self):
        if not self.original_parts:
            return []
        parts = list(self.original_parts.items())
        parts.sort(key=self.orchestration.sorter())
        return [ (MusicTag.from_tag(x[0]), x[1]) for x in parts ]

    @property
    def tags(self):
        return self.meta_info.filter(name='tag').values_list('value', flat=True)

    @property
    def meta(self):
        return self.meta_info.exclude(name='tag')

    @property
    def active_projects(self):
        return self.projects.filter(active=True)

    @property
    def current_loans(self):
        return self.project_items.filter(checkout__lte=now(), returned=None).select_related('project')

    @cached_property
    def loans(self):
        try:
            return self.loan_count
        except AttributeError:
            return self.project_items.filter(checkout__lte=now(), returned=None).count()

    @property
    def is_available(self):
        if self.max_projects < 0:
            return True
        return self.max_projects > self.loans

    @property
    def available(self):
        if self.max_projects < 0:
            return 'Unlimited'
        a = self.max_projects - self.loans
        return '{0} of {1}'.format(max(a, 0), self.max_projects)

    @property
    def identifier(self):

        if self.code:
            return self.code;

        composer = self.composer or "Anon"
        composer = re.sub('[^\w]', '', composer)
        words = self.name.split()
        work = words[0][:3]

        return f"{composer[:4]}-{work}-{self.pk:05d}".upper()

    def assigned_instruments(self):
        return Section.objects.filter(doc__work_id=self.pk).values_list('tag', flat=True)

    def unassigned_instruments(self):
        assigned = set(self.assigned_instruments())
        return [ x for x in self.orchestration.as_list() if not x[0] in assigned ]

    def __str__(self):
        return f"{self.name} ({self.composer})"

class WorkMeta(models.Model):

    META_CHOICES = (
        ('tag', 'Tag'),
        ('arr', 'Arranger'),
        ('lyrics', 'Lyracist'),
        ('genre', 'Genre'),
        ('style', 'Style'),
        ('orchestration', 'Orchestration'),
    )
    
    work = models.ForeignKey(Work, on_delete=models.CASCADE, related_name='meta_info')
    name = models.SlugField(max_length=20, choices=META_CHOICES)
    value = models.CharField(max_length=255)

def doc_upload_filename(doc, filename):
    collection = doc.work.collection
    storage = collection.storage
    if not storage:
        raise RuntimeError("Collection has no storage attached")
    return f'{storage}:library/{collection.prefix}/{doc.work.folder}/{filename}'

class Document(models.Model):
    """
    Document represents a single file stored in the storage backend.
    """

    DOCTYPE_PDF = 1
    DOCTYPE_AUDIO = 2
    DOCTYPE_VIDEO = 3
    DOCTYPE_SOURCE = 4

    DOCTYPES = (
        (DOCTYPE_PDF, 'PDF'),
        (DOCTYPE_AUDIO, 'Audio'),
        (DOCTYPE_VIDEO, 'Video'),
        (DOCTYPE_SOURCE, 'Source'),
    )

    work = models.ForeignKey('Work', on_delete=models.CASCADE, related_name="docs")
    doctype = models.PositiveSmallIntegerField(choices=DOCTYPES, default=DOCTYPE_PDF)
    upload = models.FileField(upload_to=doc_upload_filename, storage=library_storage)
    created = models.DateTimeField(auto_now_add=True)
    version = models.CharField(max_length=30, blank=True)

    def delete(self, *args, **kwargs):
        self.upload.delete(save=False)
        return super().delete(*args, **kwargs)

    def __str__(self):
        return self.upload.name

class Section(models.Model):
    """
    Section is a tagged portion of a Document
    """
    
    PAGE_AUTO = 0
    PAGE_LEFT = 1
    PAGE_RIGHT = 2

    PAGE_PREFERENCE = (
        (PAGE_AUTO, 'auto'),
        (PAGE_LEFT, 'left'),
        (PAGE_RIGHT, 'right'),
    )


    doc = models.ForeignKey(Document, on_delete=models.CASCADE, related_name="sections")
    tag = models.CharField(max_length=50, blank=True)
    start = models.SmallIntegerField(null=True, blank=True)
    end = models.SmallIntegerField(null=True, blank=True)
    page = models.SmallIntegerField(default=PAGE_AUTO, choices=PAGE_PREFERENCE) # NOT CURRENTLY USED

    class Meta:
        ordering = ['doc', 'start', 'pk']

    @property
    def music_tag(self):
        return MusicTag.from_tag(self.tag)

    @property
    def name(self):
        return str(self.music_tag)

    @property
    def bulma_class(self):
        return "success" if self.music_tag.is_general else 'info'

    @property
    def filename(self):
        return slugify(f'{self.doc.work.name} - {self.name}').title() + '.pdf'

    @property 
    def pagerange(self):
        if self.start:
            if self.end:
                return f"{self.start}-{self.end}"
            return str(self.start)
        return "all"

    def __str__(self):
        return self.name