def assign_colors_to_curves(blocks):
    """
    Assign a color to each curve contained in the blocks

    Parameters :

        blocks ["tag":(str),"unit":(str), "curves":[{"name":(str), "label":(str), "color":(str)}]] : a list of dictionnaries, each one representing
            a block of curves with their name, their label and their color (if found in the database), grouped by their tag (which can be the unit augmented with an index) and their unit

    Returns :
        ["tag":(str),"unit":(str), "curves":[{"name":(str), "label":(str), "color":(str), "original_color":(str)}]] : the same object as the "blocks" parameter, with the color value
            updated depending on its availability in the ColorMap, and a new "original_color" value which contains the previous "color" value
    """

    # get last value only
    for block in blocks:
        color_set = set()
        auto_curves = []
        for curve in block["curves"]:

            col = curve["color"].strip()
            c = ColorMap.to_code(col)
            if c < 0:
                valid = ColorMap.check_hex(col)
                if valid:
                    curve["original_color"] = col
                    curve["color"] = valid
                else:
                    auto_curves.append(curve)
                    curve["original_color"] = col + "?"
            else:
                color_set.add(c)
                curve["original_color"] = col
                curve["color"] = ColorMap.to_hex(c)
        c = 1 # omit white
        for curve in auto_curves:
            while c in color_set: c += 1 # find unused color
            curve["color"] = ColorMap.to_hex(c)
            c += 1

class ColorMap(object):
    '''
    ColorMap is using official CSS color names, with the exception of Green, as this
    is defined differently with X11 colors than in SEA, and used heavily in config files.
    Here Green is an alias to Lime (#00FF00) and MidGreen is #008000, which is called Green in CSS.
    The function to_code is case insensitive and accepts also names with underscores.
    The order is choosen by M. Zolliker for the SEA client, originally only the first 16 were used.
    '''
    hex_name = (("#FFFFFF","White"), ("#FF0000","Red"), ("#00FF00","Lime"), ("#0000FF","Blue"), ("#FF00FF","Magenta"),
    ("#FFFF00","Yellow"), ("#00FFFF","Cyan"), ("#000000","Black"), ("#FFA500","Orange"), ("#006400","DarkGreen"),
    ("#9400D3","DarkViolet"), ("#A52A2A","Brown"), ("#87CEEB","SkyBlue"), ("#808080","Gray"), ("#FF69B4","HotPink"),
    ("#FFFFE0","LightYellow"), ("#00FF7F","SpringGreen"), ("#000080","Navy"), ("#1E90FF","DodgerBlue"),
    ("#9ACD32","YellowGreen"), ("#008B8B","DarkCyan"), ("#808000","Olive"), ("#DEB887","BurlyWood"),
    ("#7B68EE","MediumSlateBlue"), ("#483D8B","DarkSlateBlue"), ("#98FB98","PaleGreen"), ("#FF1493","DeepPink"),
    ("#FF6347","Tomato"), ("#32CD32","LimeGreen"), ("#DDA0DD","Plum"), ("#7FFF00","Chartreuse"), ("#800080","Purple"),
    ("#00CED1","DarkTurquoise"), ("#8FBC8F","DarkSeaGreen"), ("#4682B4","SteelBlue"), ("#800000","Maroon"),
    ("#3CB371","MediumSeaGreen"), ("#FF4500","OrangeRed"), ("#BA55D3","MediumOrchid"), ("#2F4F4F","DarkSlateGray"),
    ("#CD853F","Peru"), ("#228B22","ForestGreen"), ("#48D1CC","MediumTurquoise"), ("#DC143C","Crimson"),
    ("#D3D3D3","LightGray"), ("#ADFF2F","GreenYellow"), ("#7FFFD4","Aquamarine"), ("#BC8F8F","RosyBrown"),
    ("#20B2AA","LightSeaGreen"), ("#C71585","MediumVioletRed"), ("#F0E68C","Khaki"), ("#6495ED","CornflowerBlue"),
    ("#556B2F","DarkOliveGreen"), ("#CD5C5C","IndianRed "), ("#2E8B57","SeaGreen"), ("#F08080","LightCoral"),
    ("#8A2BE2","BlueViolet"), ("#AFEEEE","PaleTurquoise"), ("#4169E1","RoyalBlue"), ("#0000CD","MediumBlue"),
    ("#B8860B","DarkGoldenRod"), ("#00BFFF","DeepSkyBlue"), ("#FFC0CB","Pink"), ("#4B0082","Indigo "), ("#A0522D","Sienna"),
    ("#FFD700","Gold"), ("#F4A460","SandyBrown"), ("#DAA520","GoldenRod"), ("#DA70D6","Orchid"), ("#E6E6FA","Lavender"),
    ("#5F9EA0","CadetBlue"), ("#D2691E","Chocolate"), ("#66CDAA","MediumAquaMarine"), ("#6B8E23","OliveDrab"),
    ("#A9A9A9","DarkGray"), ("#BDB76B","DarkKhaki"), ("#696969","DimGray"), ("#B0C4DE","LightSteelBlue"),
    ("#191970","MidnightBlue"), ("#FFE4C4","Bisque"), ("#6A5ACD","SlateBlue"), ("#EE82EE","Violet"),
    ("#8B4513","SaddleBrown"), ("#FF7F50","Coral"), ("#008000","MidGreen"), ("#DB7093","PaleVioletRed"), ("#C0C0C0","Silver"),
    ("#E0FFFF","LightCyan"), ("#9370DB","MediumPurple"), ("#FF8C00","DarkOrange"), ("#00FA9A","MediumSpringGreen"),
    ("#E9967A","DarkSalmon"), ("#778899","LightSlateGray"), ("#9932CC","DarkOrchid"), ("#EEE8AA","PaleGoldenRod"),
    ("#F8F8FF","GhostWhite"), ("#FFA07A","LightSalmon"), ("#ADD8E6","LightBlue"), ("#D8BFD8","Thistle"),
    ("#FFE4E1","MistyRose"), ("#FFDEAD","NavajoWhite"), ("#40E0D0","Turquoise"), ("#90EE90","LightGreen"),
    ("#B22222","FireBrick"), ("#008080","Teal"), ("#F0FFF0","HoneyDew"), ("#FFFACD","LemonChiffon"), ("#FFF5EE","SeaShell"),
    ("#F5F5DC","Beige"), ("#DCDCDC","Gainsboro"), ("#FA8072","Salmon"), ("#8B008B","DarkMagenta"), ("#FFB6C1","LightPink"),
    ("#708090","SlateGray"), ("#87CEFA","LightSkyBlue"), ("#FFEFD5","PapayaWhip"), ("#D2B48C","Tan"), ("#FFFFF0","Ivory"),
    ("#F0FFFF","Azure"), ("#F5DEB3","Wheat"), ("#00008B","DarkBlue"), ("#FFDAB9","PeachPuff"), ("#8B0000","DarkRed"),
    ("#FAF0E6","Linen"), ("#B0E0E6","PowderBlue"), ("#FFE4B5","Moccasin"), ("#F5F5F5","WhiteSmoke"), ("#FFF8DC","Cornsilk"),
    ("#FFFAFA","Snow"), ("#FFF0F5","LavenderBlush"), ("#FFEBCD","BlanchedAlmond"), ("#F0F8FF","AliceBlue"),
    ("#FAEBD7","AntiqueWhite"), ("#FDF5E6","OldLace"), ("#FAFAD2","LightGoldenRodYellow"), ("#F5FFFA","MintCream"),
    ("#FFFAF0","FloralWhite"), ("#7CFC00","LawnGreen"), ("#663399","RebeccaPurple"))
    codes = {}
    for i, pair in enumerate(hex_name):
        codes[pair[0]] = i
        low = pair[1].lower()
        codes[low] = i
        codes[low.replace("gray","grey")] = i
    codes["green"] = 2
    codes["fuchsia"] = 4
    codes["aqua"] = 6
        
    @staticmethod
    def to_code(colortext):
        try:
            return int(colortext)
        except ValueError:
            return ColorMap.codes.get(colortext.lower().replace("_",""),-1)
            
    @staticmethod
    def check_hex(code):
        if not code.startswith("#"):
            return None
        if len(code) == 4: # convert short code to long code
            code = code[0:2] + code[1:3] + code[2:4] + code[3]
        if len(code) != 7:
            return None
        try:
            int(code[1:], 16) # we have a valid hex color code
            return code
        except ValueError:
            return None
    
    @staticmethod
    def to_hex(code):
        try:
            return ColorMap.hex_name[code][0]
        except IndexError:
            return -1