# Copyright 2003-2009 by Bartek Wilczynski.  All rights reserved.
# This code is part of the Biopython distribution and governed by its
# license.  Please see the LICENSE file that should have been included
# as part of this package.
"""Implementation of sequence motifs (PRIVATE).
"""

from __future__ import print_function

from Bio._py3k import range

from Bio.Seq import Seq
from Bio.SubsMat import FreqTable
from Bio.Alphabet import IUPAC
import math, random

class Motif(object):
    """
    A class representing sequence motifs.
    """
    def __init__(self,alphabet=IUPAC.unambiguous_dna):
        self.instances = []
        self.has_instances=False
        self.counts = {}
        self.has_counts=False
        self.mask = []
        self._pwm_is_current = False
        self._pwm = []
        self._log_odds_is_current = False
        self._log_odds = []
        self.alphabet=alphabet
        self.length=None
        self.background=dict((n, 1.0/len(self.alphabet.letters)) \
                             for n in self.alphabet.letters)
        self.beta=1.0
        self.info=None
        self.name=""

    def _check_length(self, len):
        # TODO - Change parameter name (len clashes with built in function)?
        if self.length is None:
            self.length = len
        elif self.length != len:
            raise ValueError("You can't change the length of the motif "
                             "%r %r %r" % (self.length, self.instances, len))

    def _check_alphabet(self, alphabet):
        if self.alphabet is None:
            self.alphabet=alphabet
        elif self.alphabet != alphabet:
                raise ValueError("Wrong Alphabet")
        
    def add_instance(self, instance):
        """
        adds new instance to the motif
        """
        self._check_alphabet(instance.alphabet)
        self._check_length(len(instance))
        if self.has_counts:
            for i in range(self.length):
                let=instance[i]
                self.counts[let][i]+=1

        if self.has_instances or not self.has_counts:
            self.instances.append(instance)
            self.has_instances=True
            
        self._pwm_is_current = False
        self._log_odds_is_current = False

 
    def set_mask(self, mask):
        """
        sets the mask for the motif

        The mask should be a string containing asterisks in the position of significant columns and spaces in other columns
        """
        self._check_length(len(mask))
        self.mask=[]
        for char in mask:
            if char=="*":
                self.mask.append(1)
            elif char==" ":
                self.mask.append(0)
            else:
                raise ValueError("Mask should contain only '*' or ' ' and not a '%s'"%char)
    
    def pwm(self,laplace=True):
        """
        returns the PWM computed for the set of instances

        if laplace=True (default), pseudocounts equal to self.background multiplied by self.beta are added to all positions.
        """
        
        if self._pwm_is_current:
            return self._pwm
        #we need to compute new pwm
        self._pwm = []
        for i in range(self.length):
            dict = {}
            #filling the dict with 0's
            for letter in self.alphabet.letters:
                if laplace:
                    dict[letter]=self.beta*self.background[letter]
                else:
                    dict[letter]=0.0
            if self.has_counts:
                #taking the raw counts
                for letter in self.alphabet.letters:
                    dict[letter]+=self.counts[letter][i]
            elif self.has_instances:
                #counting the occurences of letters in instances
                for seq in self.instances:
                    #dict[seq[i]]=dict[seq[i]]+1
                    try:
                        dict[seq[i]]+=1
                    except KeyError: #we need to ignore non-alphabet letters
                        pass
            self._pwm.append(FreqTable.FreqTable(dict, FreqTable.COUNT, self.alphabet)) 
        self._pwm_is_current=1
        return self._pwm

    def log_odds(self,laplace=True):
        """
        returns the logg odds matrix computed for the set of instances
        """
        
        if self._log_odds_is_current:
            return self._log_odds
        #we need to compute new pwm
        self._log_odds = []
        pwm=self.pwm(laplace)
        for i in range(self.length):
            d = {}
            for a in self.alphabet.letters:
                    d[a]=math.log(pwm[i][a]/self.background[a], 2)
            self._log_odds.append(d)
        self._log_odds_is_current=1
        return self._log_odds

    def ic(self):
        """Method returning the information content of a motif.
        """
        res=0
        pwm=self.pwm()
        for i in range(self.length):
            res+=2
            for a in self.alphabet.letters:
                if pwm[i][a]!=0:
                    res+=pwm[i][a]*math.log(pwm[i][a], 2)
        return res

    def exp_score(self,st_dev=False):
        """
        Computes expected score of motif's instance and its standard deviation
        """
        exs=0.0
        var=0.0
        pwm=self.pwm()
        for i in range(self.length):
            ex1=0.0
            ex2=0.0
            for a in self.alphabet.letters:
                if pwm[i][a]!=0:
                    ex1+=pwm[i][a]*(math.log(pwm[i][a], 2)-math.log(self.background[a], 2))
                    ex2+=pwm[i][a]*(math.log(pwm[i][a], 2)-math.log(self.background[a], 2))**2
            exs+=ex1
            var+=ex2-ex1**2
        if st_dev:
            return exs, math.sqrt(var)
        else:
            return exs

    def search_instances(self, sequence):
        """
        a generator function, returning found positions of instances of the motif in a given sequence
        """
        if not self.has_instances:
            raise ValueError ("This motif has no instances")
        for pos in range(0, len(sequence)-self.length+1):
            for instance in self.instances:
                if instance.tostring()==sequence[pos:pos+self.length].tostring():
                    yield(pos, instance)
                    break # no other instance will fit (we don't want to return multiple hits)

    def score_hit(self,sequence,position,normalized=0,masked=0):
        """
        give the pwm score for a given position
        """
        lo=self.log_odds()
        score = 0.0
        for pos in range(self.length):
            a = sequence[position+pos]
            if not masked or self.mask[pos]:
                try:
                    score += lo[pos][a]
                except:
                    pass
        if normalized:
            if not masked:
                score/=self.length
            else:
                score/=len([x for x in self.mask if x])
        return score
    
    def search_pwm(self,sequence,normalized=0,masked=0,threshold=0.0,both=True):
        """
        a generator function, returning found hits in a given sequence with the pwm score higher than the threshold
        """
        if both:
            rc = self.reverse_complement()
            
        sequence=sequence.tostring().upper()
        for pos in range(0, len(sequence)-self.length+1):
            score = self.score_hit(sequence, pos, normalized, masked)
            if score > threshold:
                yield (pos, score)
            if both:
                rev_score = rc.score_hit(sequence, pos, normalized, masked)
                if rev_score > threshold:
                    yield (-pos, rev_score)

    def dist_pearson(self, motif, masked = 0):
        """
        return the similarity score based on pearson correlation for the given motif against self.

        We use the Pearson's correlation of the respective probabilities.
        """

        if self.alphabet != motif.alphabet:
            raise ValueError("Cannot compare motifs with different alphabets")

        max_p=-2
        for offset in range(-self.length+1, motif.length):
            if offset<0:
                p = self.dist_pearson_at(motif, -offset)
            else: #offset>=0
                p = motif.dist_pearson_at(self, offset)
            
            if max_p<p:
                max_p=p
                max_o=-offset
        return 1-max_p, max_o

    def dist_pearson_at(self, motif, offset):
        sxx = 0 # \sum x^2
        sxy = 0 # \sum x \cdot y
        sx = 0  # \sum x
        sy = 0  # \sum y
        syy = 0 # \sum x^2
        norm=max(self.length, offset+motif.length)
        
        for pos in range(max(self.length, offset+motif.length)):
            for l in self.alphabet.letters:
                xi = self[pos][l]
                yi = motif[pos-offset][l]
                sx = sx + xi
                sy = sy + yi
                sxx = sxx + xi * xi
                syy = syy + yi * yi
                sxy = sxy + xi * yi

        norm *= len(self.alphabet.letters)
        s1 = (sxy - sx*sy*1.0/norm)
        s2 = (norm*sxx - sx*sx*1.0)*(norm*syy- sy*sy*1.0)
        return s1/math.sqrt(s2)

    def dist_product(self, other):
        """
        A similarity measure taking into account a product probability of generating overlaping instances of two motifs
        """
        max_p=0.0
        for offset in range(-self.length+1, other.length):
            if offset<0:
                p = self.dist_product_at(other, -offset)
            else: #offset>=0
                p = other.dist_product_at(self, offset)
            if max_p<p:
                max_p=p
                max_o=-offset
        return 1-max_p/self.dist_product_at(self, 0), max_o
            
    def dist_product_at(self, other, offset):
        s=0
        for i in range(max(self.length, offset+other.length)):
            f1=self[i]
            f2=other[i-offset]
            for n, b in self.background.items():
                s+=b*f1[n]*f2[n]
        return s/i

    def dist_dpq(self, other):
        r"""Calculates the DPQ distance measure between motifs.

        It is calculated as a maximal value of DPQ formula (shown using LaTeX
        markup, familiar to mathematicians):
        
        \sqrt{\sum_{i=1}^{alignment.len()} \sum_{k=1}^alphabet.len() \
        \{ m1[i].freq(alphabet[k])*log_2(m1[i].freq(alphabet[k])/m2[i].freq(alphabet[k])) +
           m2[i].freq(alphabet[k])*log_2(m2[i].freq(alphabet[k])/m1[i].freq(alphabet[k]))
        }
        
        over possible non-spaced alignemts of two motifs.  See this reference:

        D. M Endres and J. E Schindelin, "A new metric for probability
        distributions", IEEE transactions on Information Theory 49, no. 7
        (July 2003): 1858-1860.
        """
        
        min_d=float("inf")
        min_o=-1
        d_s=[]
        for offset in range(-self.length+1, other.length):
            #print("%2.3d"%offset)
            if offset<0:
                d = self.dist_dpq_at(other, -offset)
                overlap = self.length+offset
            else: #offset>=0
                d = other.dist_dpq_at(self, offset)
                overlap = other.length-offset
            overlap = min(self.length, other.length, overlap)
            out = self.length+other.length - 2*overlap
            #print("%f %f %f" % (d,1.0*(overlap+out)/overlap,d*(overlap+out)/overlap))
            #d = d/(2*overlap)
            d = (d/(out+overlap))*(2*overlap+out)/(2*overlap)
            #print(d)
            d_s.append((offset, d))
            if min_d > d:
                min_d = d
                min_o = -offset
        return min_d, min_o #,d_s
            
    def dist_dpq_at(self, other, offset):
        """
        calculates the dist_dpq measure with a given offset.

        offset should satisfy 0<=offset<=len(self)
        """
        def dpq (f1, f2, alpha):
            s=0
            for n in alpha.letters:
                avg=(f1[n]+f2[n])/2
                s+=f1[n]*math.log(f1[n]/avg, 2)+f2[n]*math.log(f2[n]/avg, 2)
            return math.sqrt(s)
                
        s=0        
        for i in range(max(self.length, offset+other.length)):
            f1=self[i]
            f2=other[i-offset]
            s+=dpq(f1, f2, self.alphabet)
        return s
            
    def _read(self, stream):
        """Reads the motif from the stream (in AlignAce format).

        the self.alphabet variable must be set beforehand.
        If the last line contains asterisks it is used for setting mask
        """
        
        while True:
            ln = stream.readline()
            if "*" in ln:
                self.set_mask(ln.strip("\n\c"))
                break
            self.add_instance(Seq(ln.strip(), self.alphabet))
        
    def __str__(self,masked=False):
        """ string representation of a motif.
        """
        str = ""
        for inst in self.instances:
            str = str + inst.tostring() + "\n"

        if masked:
            for i in range(self.length):
                if self.mask[i]:
                    str = str + "*"
                else:
                    str = str + " "
            str = str + "\n"
        return str

    def __len__(self):
        """return the length of a motif

        Please use this method (i.e. invoke len(m)) instead of refering to the m.length directly.
        """
        if self.length is None:
            return 0
        else:
            return self.length
        
    def _write(self, stream):
        """
        writes the motif to the stream
        """

        stream.write(self.__str__())
            
            

    def _to_fasta(self):
        """
        FASTA representation of motif
        """
        if not self.has_instances:
            self.make_instances_from_counts()
        str = ""
        for i, inst in enumerate(self.instances):
            str = str + ">instance%d\n"%i + inst.tostring() + "\n"
            
        return str       

    def reverse_complement(self):
        """
        Gives the reverse complement of the motif
        """
        res = Motif()
        if self.has_instances:
            for i in self.instances:
                res.add_instance(i.reverse_complement())
        else: # has counts
            res.has_counts=True
            res.counts["A"]=self.counts["T"][:]
            res.counts["T"]=self.counts["A"][:]
            res.counts["G"]=self.counts["C"][:]
            res.counts["C"]=self.counts["G"][:]
            res.counts["A"].reverse()
            res.counts["C"].reverse()
            res.counts["G"].reverse()
            res.counts["T"].reverse()
            res.length=self.length
        res.mask = self.mask
        return res

        
    def _from_jaspar_pfm(self,stream,make_instances=False):
        """
        reads the motif from Jaspar .pfm file

        The instances are fake, but the pwm is accurate.
        """
        return self._from_horiz_matrix(stream, letters="ACGT", make_instances=make_instances)

    def _from_vert_matrix(self,stream,letters=None,make_instances=False):
        """reads a vertical count matrix from stream and fill in the counts.
        """

        self.counts = {}
        self.has_counts = True
        if letters is None:
            letters = self.alphabet.letters
        self.length = 0
        for i in letters:
            self.counts[i] = []
        for ln in stream.readlines():
            rec = [float(x) for x in ln.strip().split()]
            for k, v in zip(letters, rec):
                self.counts[k].append(v)
            self.length += 1
        self.set_mask("*"*self.length)
        if make_instances is True:
            self.make_instances_from_counts()
        return self
        
    def _from_horiz_matrix(self,stream,letters=None,make_instances=False):
        """reads a horizontal count matrix from stream and fill in the counts.
        """
        if letters is None:
            letters=self.alphabet.letters
        self.counts = {}
        self.has_counts=True

        for i in letters:
            ln = stream.readline().strip().split()
            #if there is a letter in the beginning, ignore it
            if ln[0] == i:
                ln = ln[1:]
            #print(ln)
            try:
                self.counts[i] = [int(x) for x in ln]
            except ValueError: #not integers
                self.counts[i] = [float(x) for x in ln]
            #print(counts[i])
        
        s = sum(self.counts[nuc][0] for nuc in letters)
        l = len(self.counts[letters[0]])
        self.length=l
        self.set_mask("*"*l)
        if make_instances is True:
            self.make_instances_from_counts()
        return self
        

    def make_instances_from_counts(self):
        """Creates "fake" instances for a motif created from a count matrix.

        In case the sums of counts are different for different columnes, the
        shorter columns are padded with background.
        """
        alpha = "".join(self.alphabet.letters)
        #col[i] is a column taken from aligned motif instances
        col = []
        self.has_instances = True
        self.instances = []
        s = sum(self.counts[nuc][0] for nuc in self.alphabet.letters)
        for i in range(self.length):
            col.append("")
            for n in self.alphabet.letters:
                col[i] = col[i] + n*(self.counts[n][i])
            if len(col[i]) < s:
                print("WARNING, column too short %i %i" % (len(col[i]), s))
                col[i] += (alpha*s)[:(s-len(col[i]))]
            #print("column %i, %s" % (i, col[i]))
        #iterate over instances
        for i in range(s): 
            inst = "" #start with empty seq
            for j in range(self.length): #iterate over positions
                inst += col[j][i]
            #print("%i %s" % (i,inst)
            inst = Seq(inst, self.alphabet)                
            self.add_instance(inst)
        return self.instances

    def make_counts_from_instances(self):
        """Creates the count matrix for a motif with instances.

        """
        #make strings for "columns" of motifs
        #col[i] is a column taken from aligned motif instances
        counts={}
        for a in self.alphabet.letters:
            counts[a]=[]
        self.has_counts=True
        s = len(self.instances)
        for i in range(self.length):
            ci = dict((a, 0) for a in self.alphabet.letters)
            for inst in self.instances:
                ci[inst[i]]+=1
            for a in self.alphabet.letters:
                counts[a].append(ci[a])
        self.counts=counts
        return counts

    def _from_jaspar_sites(self, stream):
        """
        reads the motif from Jaspar .sites file

        The instances and pwm are OK.
        """
        
        while True:
            ln = stream.readline()# read the header "$>...."
            if ln=="" or ln[0]!=">":
                break
            
            ln=stream.readline().strip()#read the actual sequence
            i=0
            while ln[i]==ln[i].lower():
                i+=1
            inst=""
            while i<len(ln) and ln[i]==ln[i].upper():
                inst+=ln[i]
                i+=1
            inst=Seq(inst, self.alphabet)                
            self.add_instance(inst)

        self.set_mask("*"*len(inst))
        return self


    def __getitem__(self, index):
        """Returns the probability distribution over symbols at a given position, padding with background.

        If the requested index is out of bounds, the returned distribution comes from background.
        """
        if index in range(self.length):
            return self.pwm()[index]
        else:
            return self.background

    def consensus(self):
        """Returns the consensus sequence of a motif.
        """
        res=""
        for i in range(self.length):
            max_f=0
            max_n="X"
            for n in sorted(self[i]):
                if self[i][n]>max_f:
                    max_f=self[i][n]
                    max_n=n
            res+=max_n
        return Seq(res, self.alphabet)

    def anticonsensus(self):
        """returns the least probable pattern to be generated from this motif.
        """
        res=""
        for i in range(self.length):
            min_f=10.0
            min_n="X"
            for n in sorted(self[i]):
                if self[i][n]<min_f:
                    min_f=self[i][n]
                    min_n=n
            res+=min_n
        return Seq(res, self.alphabet)

    def max_score(self):
        """Maximal possible score for this motif.

        returns the score computed for the consensus sequence.
        """
        return self.score_hit(self.consensus(), 0)
    
    def min_score(self):
        """Minimal possible score for this motif.

        returns the score computed for the anticonsensus sequence.
        """
        return self.score_hit(self.anticonsensus(), 0)

    def weblogo(self,fname,format="PNG",**kwds):
        """
        uses the Berkeley weblogo service to download and save a weblogo of itself
        
        requires an internet connection.
        The parameters from **kwds are passed directly to the weblogo server.
        """
        from Bio._py3k import urlopen, urlencode, Request

        al= self._to_fasta()
        url = 'http://weblogo.berkeley.edu/logo.cgi'
        values = {'sequence': al,
                  'format': format,
                  'logowidth': '18',
                  'logoheight': '5',
                  'logounits': 'cm',
                  'kind': 'AUTO',
                  'firstnum': "1",
                  'command': 'Create Logo',
                  'smallsamplecorrection': "on",
                  'symbolsperline': 32,
                  'res': '96',
                  'res_units': 'ppi',
                  'antialias': 'on',
                  'title': '',
                  'barbits': '',
                  'xaxis': 'on',
                  'xaxis_label': '',
                  'yaxis': 'on',
                  'yaxis_label': '',
                  'showends': 'on',
                  'shrink': '0.5',
                  'fineprint': 'on',
                  'ticbits': '1',
                  'colorscheme': 'DEFAULT',
                  'color1': 'green',
                  'color2': 'blue',
                  'color3': 'red',
                  'color4': 'black',
                  'color5': 'purple',
                  'color6': 'orange',
                  'color1': 'black',
                  }
        for k, v in kwds.items():
            values[k]=str(v)
            
        data = urlencode(values)
        req = Request(url, data)
        response = urlopen(req)
        with open(fname,"w") as f:
            im=response.read()
            f.write(im)
  

    def _to_transfac(self):
        """Write the representation of a motif in TRANSFAC format
        """
        res="XX\nTY Motif\n" #header
        try:
            res+="ID %s\n"%self.name
        except:
            pass
        res+="BF undef\nP0"
        for a in self.alphabet.letters:
            res+=" %s"%a
        res+="\n"
        if not self.has_counts:
            self.make_counts_from_instances()
        for i in range(self.length):
            if i<9:
                res+="0%d"%(i+1)
            else:
                res+="%d"%(i+1)
            for a in self.alphabet.letters:
                res+=" %d"%self.counts[a][i]
            res+="\n"
        res+="XX\n"
        return res

    def _to_vertical_matrix(self,letters=None):
        """Return string representation of the motif as  a matrix.
        
        """
        if letters is None:
            letters = self.alphabet.letters
        self._pwm_is_current=False
        pwm = self.pwm(laplace=False)
        res = ""
        for i in range(self.length):
            res += "\t".join(str(pwm[i][a]) for a in letters)
            res += "\n"
        return res
    
    def _to_horizontal_matrix(self,letters=None,normalized=True):
        """Return string representation of the motif as  a matrix.
        
        """
        if letters is None:
            letters = self.alphabet.letters
        res = ""
        if normalized: #output PWM
            self._pwm_is_current=False
            mat=self.pwm(laplace=False)
            for a in letters:
                res += "\t".join(str(mat[i][a]) for i in range(self.length))
                res += "\n"
        else: #output counts
            if not self.has_counts:
                self.make_counts_from_instances()
            mat = self.counts
            for a in letters:
                res += "\t".join(str(mat[a][i]) for i in range(self.length))
                res += "\n"
        return res

    def _to_jaspar_pfm(self):
        """Returns the pfm representation of the motif
        """
        return self._to_horizontal_matrix(normalized=False, letters="ACGT")

    def format(self, format):
        """Returns a string representation of the Motif in a given format

        Currently supported fromats:
         - jaspar-pfm : JASPAR Position Frequency Matrix
         - transfac : TRANSFAC like files
         - fasta : FASTA file with instances
        """

        formatters={
            "jaspar-pfm":   self._to_jaspar_pfm,
            "transfac":     self._to_transfac,
            "fasta":       self._to_fasta,
            }

        try:
            return formatters[format]()
        except KeyError:
            raise ValueError("Wrong format type")

    def scanPWM(self, seq):
        """Matrix of log-odds scores for a nucleotide sequence.
 
        scans a nucleotide sequence and returns the matrix of log-odds
        scores for all positions.

        - the result is a one-dimensional list or numpy array
        - the sequence can only be a DNA sequence
        - the search is performed only on one strand
        """
        #TODO - Code itself tolerates ambiguous bases (as NaN).
        if not isinstance(self.alphabet, IUPAC.IUPACUnambiguousDNA):
            raise ValueError("PSSM has wrong alphabet: %s - Use only with DNA motifs" \
                                 % self.alphabet)
        if not isinstance(seq.alphabet, IUPAC.IUPACUnambiguousDNA):
            raise ValueError("Sequence has wrong alphabet: %r - Use only with DNA sequences" \
                                 % sequence.alphabet)

        seq = seq.tostring()

        # check if the fast C code can be used
        try:
            import _pwm
        except ImportError:
            # use the slower Python code otherwise
            return self._pwm_calculate(seq)
        
        # get the log-odds matrix into a proper shape
        # (each row contains sorted (ACGT) log-odds values)
        logodds=[[y[1] for y in sorted(x.items())] for x in self.log_odds()]
        return _pwm.calculate(seq, logodds)

    def _pwm_calculate(self, sequence):
        logodds = self.log_odds()
        m = len(logodds)
        s = len(sequence)
        n = s - m + 1
        result = [None] * n
        for i in range(n):
            score = 0.0
            for j in range(m):
                c = sequence[i+j]
                temp = logodds[j].get(c)
                if temp is None:
                    break
                score += temp
            else:
                result[i] = score
        return result
