import difflib, string

from django.utils.translation import ugettext as _

def isatag(x): return x.startswith("<") and x.endswith(">")

def text_diff(a, b):

    res = []

    a, b = createlist(a), createlist(b)

    s = difflib.SequenceMatcher(isatag, a, b)

    for e in s.get_opcodes():

        if e[0] == "replace":

            res.append('<del class="diff modified">'+''.join(a[e[1]:e[2]]) + '</del><ins class="diff modified">'+''.join(b[e[3]:e[4]])+"</ins>")

        elif e[0] == "delete":

            res.append('<del class="diff">'+ ''.join(a[e[1]:e[2]]) + "</del>")

        elif e[0] == "insert":

            res.append('<ins class="diff">'+''.join(b[e[3]:e[4]]) + "</ins>")

        elif e[0] == "equal":

            res.append(''.join(b[e[3]:e[4]]))

        else: 

            raise "error parsing %s" %(e[0])

    return ''.join(res)

COLORS = [

'#FF0000',

'#EE0000',

'#DD0000',

'#CC0000',

'#BB0000',

'#AA0000',

'#990000',

'#880000',

'#770000',

]

from colorsys import hls_to_rgb, hsv_to_rgb

def generatePastelColors(n):

    s = .4

    v = .99

    return ['#'+''.join((hex(int(r*255))[2:],hex(int(g*255))[2:],hex(int(b*255))[2:])) for r,g,b in [hsv_to_rgb(h/200.,s,v) for h in range(1,100,100/n)]]

DEFAULT_COLOR = '#D9D9D9'

def get_colors(authors, last_white = False):

    """

    returns a dict for authors's colors (with last one white if 'last_white')

    """

    authors = set(authors)

    #new_colors = list(tuple(COLORS))

    new_colors = generatePastelColors(len(set(authors)))

    res = []

    if None in authors or '' in authors:

        res = [(_(u'unknown'),DEFAULT_COLOR) ]

    res.extend([(author,new_colors.pop()) for author in authors if author])

    #if authors[-1]:

    #    res[authors[-1]] = '#FFFFFF'

    return res

def text_history(versions, authors):

    res = versions[0]

    colors = get_colors(authors)

    for ind in range(len(versions)-1):

        author = authors[ind]

        color = colors.get(author,DEFAULT_COLOR)

        v_2 = versions[ind + 1]

        res = text_diff_add(v_2, res, color)

    return res,colors.items()

from cm.utils.html import surrond_text_node

def text_diff_add(a,b, color):

    res = []

    a, b = createlist(a), createlist(b)

    s = difflib.SequenceMatcher(isatag, a, b)

    for e in s.get_opcodes():

        if e[0] == "replace":

            html_chunk = ''.join(b[e[3]:e[4]])

            new_html_chunk = surrond_text_node(html_chunk,'<span style="background: %s;">' %color,'</span>')

            res.append(new_html_chunk)

            #res.append('<font style="background: %s;" class="diff modified">' %color+''.join(b[e[3]:e[4]])+"</font>")

        elif e[0] == "delete":

            pass

        elif e[0] == "insert":

            html_chunk = ''.join(b[e[3]:e[4]])

            new_html_chunk = surrond_text_node(html_chunk,'<span style="background: %s;">' %color,'</span>') 

            res.append(new_html_chunk)

            #res.append('<font style="background: %s;" class="diff">' %color+''.join(b[e[3]:e[4]]) + "</font>")

        elif e[0] == "equal":

            res.append(''.join(b[e[3]:e[4]]))

        else: 

            raise "error parsing %s" %(e[0])

    return ''.join(res)

def createlist(x, b=0):

    mode = 'char'

    cur = ''

    out = []

    for c in x:

        if mode == 'tag':

            if c == '>': 

                if b: cur += ']'

                else: cur += c

                out.append(cur); cur = ''; mode = 'char'

            else: cur += c

        elif mode == 'char':

            if c == '<': 

                out.append(cur)

                if b: cur = '['

                else: cur = c

                mode = 'tag'            

            elif c in string.whitespace: out.append(cur+c); cur = ''

            else: cur += c

    out.append(cur)

    return filter(lambda x: x is not '', out)