info = {
    'icon': 'TRIA_DOWN_BAR',
    'description': 'Merge layers',
}

import fnmatch
import glob
import os
import re
from math import degrees, radians
from os import listdir
from os.path import basename, dirname, exists, isdir, isfile, join, splitext
from pathlib import Path
import bpy
C = bpy.context
D = bpy.data


def random_color(alpha=False):
    import random
    if alpha:
        return (random.uniform(0,1), random.uniform(0,1), random.uniform(0,1), 1)
    return (random.uniform(0,1), random.uniform(0,1), random.uniform(0,1))

def create_node(type, tree=None, **kargs):
    tree = tree or bpy.context.scene.node_tree

    node = tree.nodes.new(type)
    for k,v in kargs.items():
        setattr(node, k, v)
    
    return node

def new_aa_node(tree):
    '''create AA node'''
    aa = create_node('CompositorNodeAntiAliasing', tree) # type = ANTIALIASING
    aa.threshold = 0.5
    aa.contrast_limit = 0.5
    aa.corner_rounding = 0.25
    aa.hide = True
    return aa

def get_render_scene():
    render = bpy.data.scenes.get('Render')
    if not render:
        render = bpy.data.scenes.new('Render')
    render.use_nodes = True
    return render


def merge_layers(rlayers, obname=None):
    print(f'Merging {len(rlayers)} layers')
    print('->', [r.layer for r in rlayers])
    print()

    if not rlayers:
        return ('ERROR', 'No render layer sent to merge')

    ng = rlayers[0].outputs[0].links[0].to_node
    rlayers.sort(key=lambda x: x.location.y, reverse=True)

    # change colors of those nodes
    color = random_color()
    for n in rlayers:
        n.use_custom_color = True
        n.color = color


    # get inside socket (group input) from outside socket list (should be already ordered)
    
    ## by name
    # for i, inp in enumerate(ng.node_tree.inputs):
    #     if inp.name == 

    # by connection order

    socket_list = []
    grp_sockets = []

    for n in rlayers:
        if n.outputs[0].links[0].to_node != ng:
            print(f'Skip {n.layer}, connect to {n.outputs[0].links[0].to_node} instead of {ng.name}')
            continue
        
        sock_in = n.outputs[0].links[0].to_socket
        for i, s in enumerate(ng.inputs):
            if s == sock_in:
                print(i, s.name)
                socket_list.append(s)
                grp_sockets.append(ng.node_tree.nodes['Group Input'].outputs[i])
                break
    
    # debug
    for inp, grps in zip(socket_list, grp_sockets):
        if inp.name != grps.name:
            print(f'\n! Problem ! : {inp.name}, {grps.name}')
            return

    ## 
    # JUST CREATE ANOTHER GROUP NODE FOR THE MERGE !
    ##


def merge_selected_layers():
    '''Merge command from selected GP layers'''
    ob = bpy.context.object
    layer_names = [l.info for l in ob.data.layers if l.select and not l.hide]
    print("layer_names", layer_names)#Dbg
    
    if len(layer_names) < 2:
        print(f'Should select multiple layers for merging')
        return

    render = bpy.data.scenes.get('Render')
    if render:
        nodes = render.node_tree.nodes
    
    clean_ob_name = bpy.path.clean_name(ob.name)
    rlayers = []
    for l in layer_names:
        ## identifier is clean_name(ob.name).layer_name
        
        idname = f'{clean_ob_name}.{l}'
        
        # check the render layer that have a parent frame
        rlayer = [n for n in nodes if n.type == 'R_LAYERS' and n.layer == idname and n.parent]
        if not rlayer:
            # send to function to generate the rlayer and connect
            # rlayer = creation
            continue

        rlayers.append(rlayer)

    merge_layers(rlayers, obname=clean_ob_name)


def merge_selected_render_layers():
    '''Merge command from selected render layers nodes'''
    render = bpy.data.scenes.get('Render')
    if not render:
        print('No render scene')
        return
    
    nodes = render.node_tree.nodes
    selection = [n for n in nodes if n.select and n.type == 'R_LAYERS']
    
    # should be from the same object:
    assert all(selection[0].layer.split('.')[0] == n.layer.split('.')[0] for n in selection), 'Not every nodes start with the same object'

    # obname = selection[0].layer.split('.')[0]
    merge_layers(selection)




# merge_selected_layers() # function to merge from GP dopesheet

merge_selected_render_layers() # function to merge from nodegroup