bl_info = {
    "name": "Import Spectrum from CSV",
    "blender": (2, 93, 0),
    "category": "Node",
    "location": "Shader Editor > Add > Spectral > Import Spectrum from CSV"
}

import bpy, csv
    
from bpy_extras.io_utils import ImportHelper
from bpy.props import BoolProperty, IntProperty, StringProperty
from bpy.types import Operator

def read_spectrum_csv(context, filepath, ignore_top_rows, wavelength_column, spectrum_column, label_node):
    if context.area.type == 'NODE_EDITOR':
        nodes = context.space_data.node_tree.nodes
    else:
        nodes = context.active_object.active_material.node_tree.nodes
    
    node = nodes.new("ShaderNodeSpectrumCurve")
    mapping = node.mapping
    points = mapping.curves[0].points
    
    mapping.use_clip = False
    
    if label_node:
        node.label = bpy.path.display_name_from_filepath(filepath)
    
    mapping.extend = 'HORIZONTAL'
    
    with open(filepath) as csvfile:
        rdr = csv.reader(csvfile)
        for i, row in enumerate(rdr):
            if i < ignore_top_rows:
                continue
            
            wavelength = float(row[wavelength_column].replace(',', '.'))
            value = float(row[spectrum_column].replace(',', '.'))
            
            point_number = i - ignore_top_rows
            if point_number < len(points):
                print(f"Set point {point_number} ({wavelength}, {value})")
                point = points[point_number]
                point.location[0] = wavelength
                point.location[1] = value
            else:
                print(f"Add point {point_number} ({wavelength}, {value})")
                point = points.new(wavelength, value)    
            point.handle_type = 'VECTOR' 
    mapping.update()

    return {'FINISHED'}


class ImportSpectrumCSV(Operator, ImportHelper):
    """Import spectrum from a CSV file as Spectrum Curves node"""
    bl_idname = "node.import_spectrum_csv"
    bl_label = "Import Spectrum from CSV"

    # ImportHelper mixin class uses this
    filename_ext = ".csv"

    filter_glob: StringProperty(
        default="*.csv",
        options={'HIDDEN'},
        maxlen=255,  # Max internal buffer length, longer would be clamped.
    )
    
    ignore_top_rows: IntProperty(
        name="Ignore Top Rows",
        description="Number of rows from the top to ignore",
        default=1,
        min=0
    )
    
    wavelength_column: IntProperty(
        name="Wavelength Column",
        description="Number of the column where the wavelength data is",
        default=1,
        min=1
    )
    
    spectrum_column: IntProperty(
        name="Spectrum Column",
        description="Number of the column where the spectrum data is",
        default=2,
        min=1
    )

    label_node: BoolProperty(
        name="Label Node",
        description="Change node label to filename",
        default=True,
    )
    
    def execute(self, context):
        return read_spectrum_csv(context, self.filepath, self.ignore_top_rows, self.wavelength_column - 1, self.spectrum_column - 1, self.label_node)



def draw_menu(self, context):
    layout = self.layout
    layout.separator()
    layout.operator("node.import_spectrum_csv")
    
def register():
    bpy.utils.register_class(ImportSpectrumCSV)
    bpy.types.NODE_MT_category_SH_NEW_SPECTRAL.append(draw_menu)
    
def unregister():
    bpy.utils.unregister_class(ImportSpectrumCSV)
    bpy.types.NODE_MT_category_SH_NEW_SPECTRAL.remove(draw_menu)