# Copyright (C) 2020 by ÿnérant, eichhornchen, nicomarg, charlse
# SPDX-License-Identifier: GPL-3.0-or-later

from random import random, randint, shuffle, choice, choices
from typing import List, Tuple

from ..interfaces import Map, Tile, Entity

DEFAULT_PARAMS = {
    "width": 120,
    "height": 35,
    "tries": 300,
    "max_rooms": 20,
    "max_room_tries": 15,
    "cross_room": 1,
    "corridor_chance": .6,
    "min_v_corr": 2,
    "max_v_corr": 6,
    "min_h_corr": 4,
    "max_h_corr": 12,
    "large_circular_room": .10,
    "circular_holes": .5,
    "loop_tries" : 40,
    "loop_max" : 5,
    "loop_threshold" : 15,
    "spawn_per_region" : [1, 2],
}

def dist(level, y1, x1, y2, x2):
    copy = [[t for t in l] for l in level]
    dist = -1
    queue, next_queue = [[y1, x1]], [0]
    while next_queue:
        next_queue = []
        dist += 1
        while queue:
            y, x = queue.pop()
            copy[y][x] = Tile.EMPTY
            if y == y2 and x == x2: 
                return dist
            for y, x in Map.neighbourhood(copy, y, x):
                if copy[y][x].can_walk():
                    next_queue.append([y, x])
        queue = next_queue
    return -1

class Generator:
    def __init__(self, params: dict = None):
        self.params = params or DEFAULT_PARAMS
        self.spawn_areas = []
        self.queued_area = None

    @staticmethod
    def room_fits(level: List[List[Tile]], y: int, x: int,
                  room: List[List[Tile]], door_y: int, door_x: int,
                  dy: int, dx: int) -> bool:
        lh, lw = len(level), len(level[0])
        rh, rw = len(room), len(room[0])
        if not(0 < y + dy < lh and 0 < x + dx < lw):
            return False
        if level[y][x] != Tile.EMPTY or level[y + dy][x + dx] != Tile.FLOOR:
            return False
        for ry in range(rh):
            for rx in range(rw):
                if room[ry][rx] == Tile.FLOOR:
                    ly, lx = y + ry - door_y, x + rx - door_x
                    # tile must be in bounds and empty
                    if not(0 <= ly < lh and 0 <= lx < lw) or \
                            level[ly][lx] == Tile.FLOOR:
                        return False
                    # so do all neighbouring tiles bc we may
                    # need to place walls there eventually
                    for ny, nx in Map.neighbourhood(level, ly, lx,
                                                    large=True, oob=True):
                        if not(0 <= ny < lh and 0 <= nx < lw) or \
                                level[ny][nx] != Tile.EMPTY:
                            return False
        return True

    @staticmethod
    def place_room(level: List[List[Tile]], y: int, x: int,
                   room: List[List[Tile]], door_y: int, door_x: int) -> None:
        rh, rw = len(room), len(room[0])
        # maybe place Tile.DOOR here ?
        level[y][x] = Tile.FLOOR
        for ry in range(rh):
            for rx in range(rw):
                if room[ry][rx] == Tile.FLOOR:
                    level[y - door_y + ry][x - door_x + rx] = Tile.FLOOR

    @staticmethod
    def add_loop(level: List[List[Tile]], y: int, x: int) -> None:
        h, w = len(level), len(level[0])
        if level[y][x] != Tile.EMPTY:
            return False
        # loop over both axis
        for dx, dy in [[0, 1], [1, 0]]:
            # then we find two floor tiles, exiting if we ever move oob
            y1, x1, y2, x2 = y, x, y, x
            while x1 >= 0 and y1 >= 0 and level[y1][x1] == Tile.EMPTY:
                y1, x1 = y1 - dy, x1 - dx
            while x2 < w and y2 < h and level[y2][x2] == Tile.EMPTY:
                y2, x2 = y2 + dy, x2 + dx
            if not(0 <= x1 <= x2 < w and 0 <= y1 <= y2 < h):
                continue

            # if adding the path would make the two tiles significantly closer
            # and its sides don't touch already placed terrain, build it
            def verify_sides():
                for Dx, Dy in [[dy, dx], [-dy, -dx]]:
                    for i in range(1, y2-y1+x2-x1):
                        if not(0<= y1+Dy+i*dy < h and 0 <= x1+Dx+i*dx < w) or \
                                level[y1+Dy+i*dy][x1+Dx+i*dx].can_walk():
                            return False
                return True
            if dist(level, y1, x1, y2, x2) < 20 and verify_sides():
                y, x = y1+dy, x1+dx
                while level[y][x] == Tile.EMPTY:
                    level[y][x] = Tile.FLOOR
                    y, x = y+dy, x+dx
                return True
        return False

    @staticmethod
    def place_walls(level: List[List[Tile]]) -> None:
        h, w = len(level), len(level[0])
        for y in range(h):
            for x in range(w):
                if not level[y][x].is_wall():
                    for ny, nx in Map.neighbourhood(level, y, x, large=True):
                        if level[ny][nx] == Tile.EMPTY:
                            level[ny][nx] = Tile.WALL

    def corr_meta_info(self) -> Tuple[int, int, int, int]:
        if random() < self.params["corridor_chance"]:
            h_sup = randint(self.params["min_v_corr"],
                            self.params["max_v_corr"]) if random() < .5 else 0
            w_sup = 0 if h_sup else randint(self.params["min_h_corr"],
                                            self.params["max_h_corr"])
            h_off = h_sup if random() < .5 else 0
            w_off = w_sup if random() < .5 else 0
            return h_sup, w_sup, h_off, w_off
        return 0, 0, 0, 0

    @staticmethod
    def build_door(room, y, x, dy, dx, length):
        rh, rw = len(room), len(room[0])
        # verify we are pointing away from a floor tile
        if not(0 <= y - dy < rh and 0 <= x - dx < rw) \
                or room[y - dy][x - dx] != Tile.FLOOR:
            return False
        # verify there's no other floor tile around us
        for ny, nx in [[y + dy, x + dx], [y - dx, x - dy],
                       [y + dx, x + dy]]:
            if 0 <= ny < rh and 0 <= nx < rw \
                    and room[ny][nx] != Tile.EMPTY:
                return False
        for i in range(length+1):
            if room[y + i * dy][x + i * dx] != Tile.EMPTY:
                return False
        for i in range(length):
            room[y + i * dy][x + i * dx] = Tile.FLOOR
        return True

    @staticmethod
    def attach_door(room: List[List[Tile]], h_sup: int, w_sup: int, 
            h_off: int, w_off: int) -> Tuple[int, int, int, int]:
        length = h_sup + w_sup
        dy, dx = 0, 0
        if length > 0:
            if h_sup:
                dy = -1 if h_off else 1
            else:
                dx = -1 if w_off else 1
        else:
            if random() < .5:
                dy = -1 if random() < .5 else 1
            else:
                dx = -1 if random() < .5 else 1

        rh, rw = len(room), len(room[0])
        yxs = [i for i in range(rh * rw)]
        shuffle(yxs)
        for pos in yxs:
            y, x = pos // rw, pos % rw
            if room[y][x] == Tile.EMPTY and \
                    Generator.build_door(room, y, x, dy, dx, length):
                break

        return y + length * dy, x + length * dx, dy, dx

    def create_circular_room(self, spawnable: bool = True) \
            -> Tuple[List[List[Tile]], int, int, int, int]:
        if random() < self.params["large_circular_room"]:
            r = randint(5, 10)
        else:
            r = randint(2, 4)

        room = []

        h_sup, w_sup, h_off, w_off = self.corr_meta_info()

        height = 2 * r + 2
        width = 2 * r + 2
        make_hole = r > 6 and random() < self.params["circular_holes"]
        r2 = 0
        if make_hole:
            r2 = randint(3, r - 3)
        for i in range(height + h_sup):
            room.append([])
            d = (i - h_off - height // 2) ** 2
            for j in range(width + w_sup):
                if d + (j - w_off - width // 2) ** 2 < r ** 2 and \
                    (not make_hole
                     or d + (j - w_off - width // 2) ** 2 >= r2 ** 2):
                    room[-1].append(Tile.FLOOR)
                else:
                    room[-1].append(Tile.EMPTY)

        if spawnable:
            self.register_spawn_area(room)
        door_y, door_x, dy, dx = self.attach_door(room, h_sup, w_sup,
                                                  h_off, w_off)

        return room, door_y, door_x, dy, dx

    def create_random_room(self, spawnable: bool = True) \
            -> Tuple[List[list], int, int, int, int]:
        return self.create_circular_room()

    def register_spawn_area(self, area:List[List[Tile]]):
        spawn_positions = []
        for y, line in enumerate(area):
            for x, tile in enumerate(line):
                if tile == Tile.FLOOR:
                    spawn_positions.append([y, x])
        self.queued_area = spawn_positions

    def update_spawnable(self, y, x):
        if self.queued_area != None:
            translated_area = [[y+ry, x+rx] for ry, rx in self.queued_area]
            self.spawn_areas.append(translated_area)
        self.queued_area = None

    def populate(self, rv):
        min_c, max_c = self.params["spawn_per_region"]
        for region in self.spawn_areas:
            entity_count = randint(min_c, max_c)
            for _dummy in range(entity_count):
                entity = choices(Entity.get_all_entity_classes(),
                                 weights=Entity.get_weights(), k=1)[0]()
                y, x = choice(region)
                entity.move(y, x)
                rv.add_entity(entity)

    def run(self) -> Map:
        height, width = self.params["height"], self.params["width"]
        level = [width * [Tile.EMPTY] for _ignored in range(height)]

        # the starting room must have no corridor
        mem, self.params["corridor_chance"] = self.params["corridor_chance"], 0
        starting_room, _, _, _, _ = self.create_random_room(spawnable = False)
        dim_v, dim_h = len(starting_room), len(starting_room[0])
        pos_y, pos_x = randint(0, height - dim_v - 1),\
            randint(0, width - dim_h - 1)
        self.place_room(level, pos_y, pos_x, starting_room, 0, 0)
        if starting_room[0][0] != Tile.FLOOR:
            level[pos_y][pos_x] = Tile.EMPTY
        self.params["corridor_chance"] = mem

        # find a starting position
        sy, sx = randint(0, height - 1), randint(0, width - 1)
        while level[sy][sx] != Tile.FLOOR:
            sy, sx = randint(0, height - 1), randint(0, width - 1)
        level[sy][sx] = Tile.LADDER

        # now we loop until we've tried enough, or we've added enough rooms
        tries, rooms_built = 0, 0
        while tries < self.params["tries"] \
                and rooms_built < self.params["max_rooms"]:

            room, door_y, door_x, dy, dx = self.create_random_room()
            positions = [i for i in range(height * width)]
            shuffle(positions)
            for pos in positions:
                y, x = pos // width, pos % width
                if self.room_fits(level, y, x, room, door_y, door_x, dy, dx):
                    self.update_spawnable(y - door_y, x - door_x)
                    self.place_room(level, y, x, room, door_y, door_x)
                    rooms_built += 1
                    break
            tries += 1

        # post-processing
        self.place_walls(level)
        tries, loops = 0, 0
        while tries < self.params["loop_tries"] and \
                loops < self.params["loop_max"]:
            tries += 1
            y, x = randint(0, height-1), randint(0, width-1)
            loops += self.add_loop(level, y, x)

        # place an exit ladder
        y, x = randint(0, height - 1), randint(0, width - 1)
        while level[y][x] != Tile.FLOOR or \
                any([level[j][i].is_wall() for j, i
                     in Map.neighbourhood(level, y, x, large=True)]):
            y, x = randint(0, height - 1), randint(0, width - 1)
        level[y][x] = Tile.LADDER

        # spawn entities
        rv = Map(width, height, level, sy, sx)
        self.populate(rv)

        return rv