from __future__ import annotations

from dataclasses import dataclass
from typing import Iterable, Optional

import pygame

from src.assets import AssetLibrary


@dataclass(frozen=True)
class LayerSpec:
    path_parts: tuple[str, ...]
    speed_factor: float
    alpha: int = 255
    colorkey: tuple[int, int, int] | None = None


class ParallaxBackground:
    """
    Parallax background using Foozle environment pack layers.

    Source images are very wide strips (e.g., 5760x360). We scale each layer to
    screen height and tile horizontally with a scrolling offset.
    """

    def __init__(self, screen_size: tuple[int, int], assets: AssetLibrary):
        self.w, self.h = screen_size
        self.assets = assets
        self.base_speed = 80.0  # px/sec; tuned for current prototype
        self.offset = 0.0

        self.layers: list[tuple[pygame.Surface, float]] = []
        self._apply_layer_specs(list(self._default_layers()))

        self.planet: Optional[pygame.Surface] = self._load_planet()
        self.planet_pos = pygame.Vector2(self.w * 0.75, self.h * 0.25)
        self.planet_speed = 10.0
        self.tint_mult = (255, 255, 255)
        self._tint_surface: Optional[pygame.Surface] = None
        self.nebula: Optional[pygame.Surface] = None
        self.nebula_factor: float = 0.10

    def set_tint_mult(self, rgb: tuple[int, int, int]) -> None:
        self.tint_mult = (int(rgb[0]), int(rgb[1]), int(rgb[2]))
        if self.tint_mult == (255, 255, 255):
            self._tint_surface = None
            return
        self._tint_surface = pygame.Surface((self.w, self.h))
        self._tint_surface.fill(self.tint_mult)

    def _default_layers(self) -> Iterable[LayerSpec]:
        # Prefer Split up layers for flexibility.
        base = (
            "Foozle_2DS0015_Void_EnvironmentPack",
            "Backgrounds",
            "PNGs",
            "Split up",
        )
        return [
            LayerSpec(base + ("Starry background  - Layer 01 - Solid colour.png",), 0.15),
            LayerSpec(base + ("Starry background  - Layer 02 - Shadows.png",), 0.35),
            LayerSpec(base + ("Starry background  - Layer 03 - Stars.png",), 0.70),
        ]

    def _apply_layer_specs(self, specs: list[LayerSpec]) -> None:
        self.layers = []
        for spec in specs:
            surf = self._load_layer(spec.path_parts)
            if surf is None:
                continue
            if spec.colorkey is not None:
                surf.set_colorkey(spec.colorkey)
            if spec.alpha != 255:
                surf.set_alpha(spec.alpha)
            self.layers.append((surf, spec.speed_factor))

    def set_layers(self, specs: Iterable[LayerSpec]) -> None:
        self._apply_layer_specs(list(specs))

    def _load_layer(self, parts: tuple[str, ...]) -> Optional[pygame.Surface]:
        path = self.assets.resolve("environment_pack", *parts[1:]) if parts[0] == "Foozle_2DS0015_Void_EnvironmentPack" else self.assets.resolve(parts[0], *parts[1:])
        if not path.exists():
            return None
        img = self.assets.load_image(path)
        # Scale to screen height, preserve aspect ratio.
        scale = self.h / img.get_height()
        new_w = max(1, int(img.get_width() * scale))
        scaled = pygame.transform.smoothscale(img, (new_w, self.h))
        return scaled

    def _load_planet(self) -> Optional[pygame.Surface]:
        path = self.assets.resolve(
            "environment_pack",
            "Planets",
            "PNGs",
            "Earth-Like planet.png",
        )
        if not path.exists():
            return None
        img = self.assets.load_image(path)
        target = 140
        scale = target / max(1, img.get_width())
        w = max(1, int(img.get_width() * scale))
        h = max(1, int(img.get_height() * scale))
        return pygame.transform.smoothscale(img, (w, h))

    def set_planet_variant(self, variant: str, *, scale: float = 1.0) -> None:
        if variant == "none":
            self.planet = None
            return
        planet_file = "Earth-Like planet.png" if variant == "glow" else "Earth-Like planet - Without back glow.png"
        path = self.assets.resolve("environment_pack", "Planets", "PNGs", planet_file)
        if not path.exists():
            self.planet = None
            return
        img = self.assets.load_image(path)
        target = int(140 * max(0.5, float(scale)))
        s = target / max(1, img.get_width())
        w = max(1, int(img.get_width() * s))
        h = max(1, int(img.get_height() * s))
        self.planet = pygame.transform.smoothscale(img, (w, h))
        self.planet_pos = pygame.Vector2(self.w * 0.75, self.h * 0.25)

    def set_nebula(
        self,
        *,
        seed: int | None,
        colors: tuple[tuple[int, int, int], ...],
        alpha: int = 80,
        factor: float = 0.10,
    ) -> None:
        self.nebula_factor = float(factor)
        if seed is None or not colors:
            self.nebula = None
            return
        import random

        rng = random.Random(int(seed))
        surf = pygame.Surface((self.w * 2, self.h), pygame.SRCALPHA)
        surf.fill((0, 0, 0, 0))
        for _ in range(30):
            col = rng.choice(list(colors))
            radius = rng.randint(90, 240)
            x = rng.randint(-radius, surf.get_width() + radius)
            y = rng.randint(-radius, self.h + radius)
            a = rng.randint(max(20, int(alpha) - 40), min(150, int(alpha) + 35))
            pygame.draw.circle(surf, (int(col[0]), int(col[1]), int(col[2]), a), (x, y), radius)
        self.nebula = surf

    def set_planet_from_layer(self, path_parts: tuple[str, ...], *, scale: float = 1.0) -> None:
        try:
            path = self.assets.resolve(path_parts[0], *path_parts[1:])
        except Exception:
            self.planet = None
            return
        if not path.exists():
            self.planet = None
            return
        img = self.assets.load_image(path)
        target = int(140 * max(0.5, float(scale)))
        s = target / max(1, img.get_width())
        w = max(1, int(img.get_width() * s))
        h = max(1, int(img.get_height() * s))
        self.planet = pygame.transform.smoothscale(img, (w, h))
        self.planet_pos = pygame.Vector2(self.w * 0.75, self.h * 0.25)

    def configure_theme(
        self,
        *,
        shadows_variant: int = 0,
        stars_variant: int = 0,
        extras: tuple[str, ...] = (),
        tint_mult: tuple[int, int, int] = (255, 255, 255),
        planet_variant: str = "glow",  # glow | noglow | none
        planet_scale: float = 1.0,
        nebula_seed: int | None = None,
        nebula_colors: tuple[tuple[int, int, int], ...] = (),
        nebula_alpha: int = 80,
    ) -> None:
        base = ("Foozle_2DS0015_Void_EnvironmentPack", "Backgrounds", "PNGs", "Split up")
        shadows_file = "Starry background  - Layer 02 - Shadows.png" if int(shadows_variant) == 0 else "Starry background  - Layer 02 - Shadows 2.png"
        stars_file = "Starry background  - Layer 03 - Stars.png" if int(stars_variant) == 0 else "Starry background  - Layer 03 - Stars 2.png"
        specs: list[LayerSpec] = [
            LayerSpec(base + ("Starry background  - Layer 01 - Solid colour.png",), 0.15),
            LayerSpec(base + (shadows_file,), 0.35),
            LayerSpec(base + (stars_file,), 0.70),
        ]
        extra_map = {
            "big_star": "Starry background - Layer X - Big Star.png",
            "big_star_2": "Starry background - Layer X - Big Star 2.png",
            "black_hole": "Starry background - Layer X -Black hole.png",
            "rotary_star": "Starry background - Layer X -Rotary Star.png",
            "rotary_star_2": "Starry background - Layer X -Rotary Star 2.png",
        }
        for key in extras:
            name = extra_map.get(str(key))
            if name:
                # Extras should be subtle; keep low opacity to avoid dominating the scene.
                specs.append(LayerSpec(base + (name,), 0.10, alpha=120))
        self._apply_layer_specs(specs)
        self.set_tint_mult(tint_mult)

        # Planet
        if planet_variant == "none":
            self.planet = None
        else:
            planet_file = "Earth-Like planet.png" if planet_variant == "glow" else "Earth-Like planet - Without back glow.png"
            path = self.assets.resolve("environment_pack", "Planets", "PNGs", planet_file)
            if path.exists():
                img = self.assets.load_image(path)
                target = int(140 * max(0.5, float(planet_scale)))
                scale = target / max(1, img.get_width())
                w = max(1, int(img.get_width() * scale))
                h = max(1, int(img.get_height() * scale))
                self.planet = pygame.transform.smoothscale(img, (w, h))
            else:
                self.planet = None
        self.planet_pos = pygame.Vector2(self.w * 0.75, self.h * 0.25)

        # Nebula overlay (procedural), wide so it tiles.
        self.set_nebula(seed=nebula_seed, colors=nebula_colors, alpha=nebula_alpha, factor=self.nebula_factor)

    def update(self, dt: float):
        self.offset += self.base_speed * dt
        if self.offset > 1_000_000:
            self.offset = 0.0

        if self.planet is not None:
            self.planet_pos.x -= self.planet_speed * dt
            if self.planet_pos.x < -200:
                self.planet_pos.x = self.w + 200

    def draw(self, surface: pygame.Surface):
        for layer, factor in self.layers:
            self._draw_tiled(surface, layer, self.offset * factor)
        if self.planet is not None:
            rect = self.planet.get_rect(center=(int(self.planet_pos.x), int(self.planet_pos.y)))
            surface.blit(self.planet, rect)
        if self.nebula is not None:
            self._draw_tiled(surface, self.nebula, self.offset * self.nebula_factor)
        if self._tint_surface is not None:
            surface.blit(self._tint_surface, (0, 0), special_flags=pygame.BLEND_RGB_MULT)

    def _draw_tiled(self, surface: pygame.Surface, img: pygame.Surface, x_offset: float):
        w = img.get_width()
        # Scroll left-to-right: subtract offset for left movement.
        x = -int(x_offset) % w
        x -= w
        while x < self.w:
            surface.blit(img, (x, 0))
            x += w