import bpy
import bmesh
import operator
from mathutils import Vector
from collections import defaultdict
from math import pi

from . import utilities_uv


class op(bpy.types.Operator):
    bl_idname = "uv.textools_select_islands_identical"
    bl_label = "Select identical"
    bl_description = "Select identical UV islands with similar topology"
    bl_options = {'REGISTER', 'UNDO'}

    @classmethod
    def poll(cls, context):
        if not bpy.context.active_object:
            return False
        
        if bpy.context.active_object.type != 'MESH':
            return False

        #Only in Edit mode
        if bpy.context.active_object.mode != 'EDIT':
            return False

        #Only in UV editor mode
        if bpy.context.area.type != 'IMAGE_EDITOR':
            return False

        ##Requires UV map
        if not bpy.context.object.data.uv_layers:
            return False

        #Not in Synced mode
        if bpy.context.scene.tool_settings.use_uv_select_sync:
            return False

        return True


    def execute(self, context):
        swap(self, context)
        return {'FINISHED'}


def swap(self, context):

    bm = bmesh.from_edit_mesh(bpy.context.active_object.data)
    uv_layers = bm.loops.layers.uv.verify()

    # Get selected island
    islands = utilities_uv.getSelectionIslands()

    if len(islands) != 1:
        self.report({'ERROR_INVALID_INPUT'}, "Please select only 1 UV Island")
        return
    
    island_stats_source = Island_stats(islands[0])

    bpy.context.scene.tool_settings.uv_select_mode = 'FACE'
    bpy.ops.uv.select_all(action='SELECT')

    islands_all = utilities_uv.getSelectionIslands()
    islands_equal = []
    for island in islands_all:
        island_stats = Island_stats(island)

        if island_stats_source.isEqual(island_stats):
            islands_equal.append(island_stats.faces)

    print("Islands: "+str(len(islands_equal))+"x")

    bpy.ops.uv.select_all(action='DESELECT')
    for island in islands_equal:
        for face in island:
            for loop in face.loops:
                if not loop[uv_layers].select:
                    loop[uv_layers].select = True



class Island_stats:
    countFaces = 0
    countVerts = 0
    faces = []
    area = 0
    countLinkedEdges = 0
    countLinkedFaces = 0
    

    def __init__(self, faces):
        bm = bmesh.from_edit_mesh(bpy.context.active_object.data);
        uv_layers = bm.loops.layers.uv.verify();
        
        # Collect topology stats
        self.faces = faces
        verts = []
        for face in faces:
            self.countFaces+=1
            self.area+=face.calc_area()

            for loop in face.loops:
                if loop.vert not in verts:
                    verts.append(loop.vert)
                    self.countVerts+=1
                    self.countLinkedEdges+= len(loop.vert.link_edges)
                    self.countLinkedFaces+= len(loop.vert.link_faces)
        
    def isEqual(self, other):
        if self.countVerts != other.countVerts:
            return False
        if self.countFaces != other.countFaces:
            return False

        if self.countLinkedEdges != other.countLinkedEdges:
            return False
        if self.countLinkedFaces != other.countLinkedFaces:
            return False

        # area needs to be 90%+ identical
        if min(self.area, other.area)/max(self.area, other.area) < 0.7:
            return False

        return True


bpy.utils.register_class(op)