import math
import os
import re
from pathlib import Path
from urllib.parse import urljoin

from django.conf import settings
from django.db import models
from django.urls import reverse

from troggle.core.utils import height_from_utm, throw

# from troggle.core.models.troggle import DataIssue # circular import. Hmm

class SurvexFile(models.Model):
    path = models.CharField(max_length=200)
    #survexdirectory = models.ForeignKey("SurvexDirectory", blank=True, null=True, on_delete=models.SET_NULL)
    primary = models.ForeignKey(
        "SurvexFile", related_name="primarysurvex", blank=True, null=True, on_delete=models.SET_NULL
        )
    cave = models.ForeignKey("Cave", blank=True, null=True, on_delete=models.SET_NULL)

    class Meta:
        ordering = ("id",)

    # Don't change from the default as that breaks troggle webpages and internal referencing!
    # def __str__(self):
    # return "[SurvexFile:"+str(self.path) + "-" + str(self.survexdirectory) + "-" + str(self.cave)+"]"

    def exists(self):
        """This is only used within the Django templates
        """
        fname = Path(settings.SURVEX_DATA, self.path + ".svx")
        return fname.is_file()

    # Don't change from the default as that breaks troggle webpages and internal referencing!
    # def __str__(self):
    # return "[SurvexFile:"+str(self.path) + "-" + str(self.survexdirectory) + "-" + str(self.cave)+"]"

    def __str__(self):
        return self.path


class SurvexStationLookUpManager(models.Manager):
    """what this does, 
    https://docs.djangoproject.com/en/dev/topics/db/managers/
    This changes the .objects thinggy to use a case-insensitive match name__iexact
    so that now SurvexStation.objects.lookup() works as a case-insensitive match
    """
    def lookup(self, name):
        blocknames, sep, stationname = name.rpartition(".")
        return self.get(block=SurvexBlock.objects.lookup(blocknames), name__iexact=stationname)


class SurvexStation(models.Model):
    name = models.CharField(max_length=100)
    # block = models.ForeignKey("SurvexBlock", null=True, on_delete=models.SET_NULL)
    # block not used since 2020. survex stations objects are only used for entrance locations and all taken from the .3d file
    objects = SurvexStationLookUpManager() # overwrites SurvexStation.objects and enables lookup() 
    x = models.FloatField(blank=True, null=True)
    y = models.FloatField(blank=True, null=True)
    z = models.FloatField(blank=True, null=True)
    entrance = models.ForeignKey("Entrance", blank=True, null=True, on_delete=models.SET_NULL)

    class Meta:
        ordering = ("id",)

    def __str__(self):
        return self.name and str(self.name) or "no name"
        
    def latlong(self):
        return utmToLatLng(33, self.x, self.y, northernHemisphere=True)
    def lat(self):
        return utmToLatLng(33, self.x, self.y, northernHemisphere=True)[0]
    def long(self):
        return utmToLatLng(33, self.x, self.y, northernHemisphere=True)[1]
        
    def srtm_alt(self):
        """Caches the srtm data so that searches are not done twice on the same page"""
        if not hasattr(self,"srtm"):
           self.srtm = height_from_utm(self.x, self.y) # height, distance from reference point
        return self.srtm # (nearest point, nearest distance)
 
    def srtm_diff(self):
        alt, ref = self.srtm_alt()
        
        diff = alt - self.z
        if diff >= 0.3:
            colour = "blue"
            sign = "+"
        elif diff <= -0.3:
            colour = "red"
            sign = ""
        else:
            diff = 0
            colour = "grey"
            sign = ""
       
            
        if abs(diff) > 60:
            weight = "bold"
        else:
            weight = "normal"
            
        diff_str = f"<span style='color:{colour}; font-weight:{weight}'>{sign}{diff:.0f}</span>"
        
        if ref >= throw:
            colour = "grey"
            weight = "normal"
            diff = "XX"
            ref = float("nan")
            diff_str = f"<span style='color:{colour}'>XX</span>"
            
        return diff_str, ref
 
        
    

def utmToLatLng(zone, easting, northing, northernHemisphere=True): # move this to utils.py ?
    if not northernHemisphere:
        northing = 10000000 - northing

    a = 6378137
    e = 0.081819191
    e1sq = 0.006739497
    k0 = 0.9996

    arc = northing / k0
    mu = arc / (a * (1 - math.pow(e, 2) / 4.0 - 3 * math.pow(e, 4) / 64.0 - 5 * math.pow(e, 6) / 256.0))

    ei = (1 - math.pow((1 - e * e), (1 / 2.0))) / (1 + math.pow((1 - e * e), (1 / 2.0)))

    ca = 3 * ei / 2 - 27 * math.pow(ei, 3) / 32.0

    cb = 21 * math.pow(ei, 2) / 16 - 55 * math.pow(ei, 4) / 32
    cc = 151 * math.pow(ei, 3) / 96
    cd = 1097 * math.pow(ei, 4) / 512
    phi1 = mu + ca * math.sin(2 * mu) + cb * math.sin(4 * mu) + cc * math.sin(6 * mu) + cd * math.sin(8 * mu)

    n0 = a / math.pow((1 - math.pow((e * math.sin(phi1)), 2)), (1 / 2.0))

    r0 = a * (1 - e * e) / math.pow((1 - math.pow((e * math.sin(phi1)), 2)), (3 / 2.0))
    fact1 = n0 * math.tan(phi1) / r0

    _a1 = 500000 - easting
    dd0 = _a1 / (n0 * k0)
    fact2 = dd0 * dd0 / 2

    t0 = math.pow(math.tan(phi1), 2)
    Q0 = e1sq * math.pow(math.cos(phi1), 2)
    fact3 = (5 + 3 * t0 + 10 * Q0 - 4 * Q0 * Q0 - 9 * e1sq) * math.pow(dd0, 4) / 24

    fact4 = (61 + 90 * t0 + 298 * Q0 + 45 * t0 * t0 - 252 * e1sq - 3 * Q0 * Q0) * math.pow(dd0, 6) / 720

    lof1 = _a1 / (n0 * k0)
    lof2 = (1 + 2 * t0 + Q0) * math.pow(dd0, 3) / 6.0
    lof3 = (5 - 2 * Q0 + 28 * t0 - 3 * math.pow(Q0, 2) + 8 * e1sq + 24 * math.pow(t0, 2)) * math.pow(dd0, 5) / 120
    _a2 = (lof1 - lof2 + lof3) / math.cos(phi1)
    _a3 = _a2 * 180 / math.pi

    latitude = 180 * (phi1 - fact1 * (fact2 + fact3 + fact4)) / math.pi

    if not northernHemisphere:
        latitude = -latitude

    longitude = ((zone > 0) and (6 * zone - 183.0) or 3.0) - _a3

    return (latitude, longitude)

#
# Single SurvexBlock
#
class SurvexBlockLookUpManager(models.Manager):
    """what this does,  
    https://docs.djangoproject.com/en/dev/topics/db/managers/ 
    
    This adds a method to the .objects thinggy to use a case-insensitive match name__iexact
    so that now SurvexBlock.objects.lookup() works as a case-insensitive match.
    This is used in lookup() in SurvexStationLookUpManager()  
    which is used in Entrance().other_location() which is used in the Cave webpage
    """
    def lookup(self, name):
        if name == "":
            blocknames = []
        else:
            blocknames = name.split(".")
        block = SurvexBlock.objects.get(parent=None, survexfile__path=settings.SURVEX_TOPNAME)
        for blockname in blocknames:
            block = SurvexBlock.objects.get(parent=block, name__iexact=blockname)
        return block


class SurvexBlock(models.Model):
    """One begin..end block within a survex file. The basic element of a survey trip.
    Multiple anonymous survex blocks are possible within the same surfex file
    Blocks can span several *included survexfile though.
    """

    objects = SurvexBlockLookUpManager() # overwrites SurvexBlock.objects and enables lookup()
    name = models.CharField(max_length=100)
    title = models.CharField(max_length=200)
    parent = models.ForeignKey("SurvexBlock", blank=True, null=True, on_delete=models.SET_NULL)

    date = models.DateField(blank=True, null=True)
    expedition = models.ForeignKey("Expedition", blank=True, null=True, on_delete=models.SET_NULL)
    # if the survexfile object is deleted, then all the survex-blocks in it should be too,
    # though a block can span more than one file...
    survexfile = models.ForeignKey("SurvexFile", blank=True, null=True, on_delete=models.CASCADE)
    # survexpath = models.CharField(max_length=200, blank=True, null=True)  No need for this anymore

    scanswallet = models.ForeignKey(
        "Wallet", null=True, on_delete=models.SET_NULL
    )  # only ONE wallet per block. The most recent seen overwites.. ugh.

    legsall = models.IntegerField(null=True)  # summary data for this block
    legslength = models.FloatField(null=True)

    class Meta:
        ordering = ("id",)

    def __str__(self):
        return self.name and str(self.name) or "no_name-#" + str(self.id)

    def isSurvexBlock(self):  # Function used in templates
        return True

    def DayIndex(self):
        """This is used to set different colours for the different trips on
        the calendar view of the expedition"""
        # print(f"SurvexBlock DayIndex {self.name} '{self.date}'  {len(list(SurvexBlock.objects.filter(date=self.date)))} on this date")
        mx = 10
        todays = list(SurvexBlock.objects.filter(date=self.date))
        if self in todays:
            index = todays.index(self)
        else:
            print(f"DayIndex: Synchronization error in survex blocks. Restart server or do full reset.  {self}")
            index = 0
        if index not in range(0, mx):
            print(f"DayIndex: More than {mx-1} SurvexBlock items on one day '{index}' {self}, restarting colour sequence.")
            index = index % mx
        return index


class SurvexPersonRole(models.Model):
    """The CASCADE means that if a SurvexBlock or a Person is deleted, then the SurvexPersonRole 
    is deleted too
    """
    survexblock = models.ForeignKey("SurvexBlock", on_delete=models.CASCADE)
    # increasing levels of precision, Surely we only need survexblock and (either person or personexpedition)?
    personname = models.CharField(max_length=100)
    person = models.ForeignKey("Person", blank=True, null=True, on_delete=models.CASCADE) # not needed
    personexpedition = models.ForeignKey("PersonExpedition", blank=True, null=True, on_delete=models.SET_NULL)

    def __str__(self):
        return str(self.personname) + " - " + str(self.survexblock)


class SingleScan(models.Model):
    """A single file holding an image. Could be raw notes, an elevation plot or whatever"""

    ffile = models.CharField(max_length=200)
    name = models.CharField(max_length=200)
    wallet = models.ForeignKey("Wallet", null=True, on_delete=models.SET_NULL)

    class Meta:
        ordering = ("name",)

    def get_absolute_url(self):
        # we do not use URL_ROOT any more.
        return reverse("scansingle", kwargs={"path": re.sub("#", "%23", self.wallet.walletname), "file": self.name})

    def __str__(self):
        return "Scan Image: " + str(self.name) + " in " + str(self.wallet)


class DrawingFile(models.Model):
    """A file holding a Therion (several types) or a Tunnel drawing
    Most of the implied capabilities are not implemented yet"""

    dwgpath = models.CharField(max_length=200)
    dwgname = models.CharField(max_length=200)
    dwgwallets = models.ManyToManyField("Wallet")  # implicitly links via folders to scans to SVX files
    scans = models.ManyToManyField("SingleScan")  # implicitly links via scans to SVX files
    dwgcontains = models.ManyToManyField("DrawingFile")  # case when its a frame type
    filesize = models.IntegerField(default=0)
    npaths = models.IntegerField(default=0)
    survexfiles = models.ManyToManyField("SurvexFile")  # direct link to SVX files - not populated yet

    class Meta:
        ordering = ("dwgpath",)

    def __str__(self):
        return "Drawing File: " + str(self.dwgname) + " (" + str(self.filesize) + " bytes)"