"""Item icons rendered from the jars' item models into build/field-guide/icons/.

Flat items composite their layer textures; block items get a small isometric
cube from their block model's faces; cross-shaped plants use their texture.
The PNGs are third-party assets (Cobblemon's assets are not MPL-licensed), so
they only ever go to build/ and are never committed.
"""
import io

from PIL import Image, ImageEnhance

from .datasource import split_id

S = 16
FACES = {  # texture keys tried for each visible face of a cube
    "top": ("up", "top", "end", "all", "texture", "side", "particle"),
    "left": ("south", "front", "side", "all", "texture", "north", "particle"),
    "right": ("east", "side", "all", "texture", "west", "particle"),
}
FLAT_PARENTS = ("item/generated", "item/handheld", "item/handheld_rod", "builtin/generated")
CROSS_PARENTS = ("block/cross", "block/tinted_cross", "block/flower_pot_cross", "block/crop")
FOLIAGE = (72, 181, 24)


class Icons:
    def __init__(self, stack, out_dir):
        self.stack, self.out = stack, out_dir
        self.models = {}
        self.missing = []

    def model(self, mid):
        """Merged model: (parent chain ids, textures, elements)."""
        if mid in self.models:
            return self.models[mid]
        ns, path = split_id(mid)
        d = self.stack.json(f"assets/{ns}/models/{path}.json") or {}
        chain, textures, elements = [f"{ns}:{path}"], {}, d.get("elements")
        parent = d.get("parent")
        if parent and len(chain) < 20:
            pchain, ptex, pel = self.model(parent if ":" in parent else "minecraft:" + parent)
            chain += pchain
            textures.update(ptex)
            elements = elements or pel
        textures.update(d.get("textures", {}))
        self.models[mid] = (chain, textures, elements)
        return self.models[mid]

    def texture(self, ref, textures, depth=0):
        while isinstance(ref, str) and ref.startswith("#") and depth < 10:
            ref, depth = textures.get(ref[1:]), depth + 1
        if not isinstance(ref, str):
            return None
        ns, path = split_id(ref)
        raw = self.stack.read(f"assets/{ns}/textures/{path}.png")
        if raw is None:
            return None
        img = Image.open(io.BytesIO(raw)).convert("RGBA")
        if img.height > img.width:  # animated strip: first frame
            img = img.crop((0, 0, img.width, img.width))
        return img.resize((S, S), Image.NEAREST) if img.size != (S, S) else img

    def render(self, iid):
        ns, path = split_id(iid)
        chain, tex, elements = self.model(f"{ns}:item/{path}")
        if len(chain) == 1 and not tex:
            chain, tex, elements = self.model(f"{ns}:block/{path}")
        if len(chain) == 1 and not tex:  # no model at all: KubeJS items get item/generated with their own texture
            chain, tex = [f"{ns}:item/{path}", "minecraft:item/generated"], {"layer0": f"{ns}:item/{path}"}
        names = [c.split(":", 1)[1] for c in chain]
        if any(n in FLAT_PARENTS for n in names) or any(k.startswith("layer") for k in tex):
            layers = sorted((k for k in tex if k.startswith("layer")), key=lambda k: int(k[5:] or 0))
            img = None
            for k in layers:
                t = self.texture(tex[k], tex)
                if t is not None:
                    img = t if img is None else Image.alpha_composite(img, t)
            return img.resize((32, 32), Image.NEAREST) if img else None
        if any(n in CROSS_PARENTS for n in names):
            t = self.texture(tex.get("cross") or tex.get("crop") or tex.get("plant") or tex.get("particle"), tex)
            return t.resize((32, 32), Image.NEAREST) if t else None
        faces = {}
        for face, keys in FACES.items():
            for k in keys:
                if k in tex:
                    faces[face] = self.texture(tex[k], tex)
                    if faces[face] is not None:
                        break
        if not any(v is not None for v in faces.values()):
            return None
        tinted = any(n in ("block/leaves",) for n in names) or path.endswith("leaves")
        return iso_cube(faces, tinted)

    def write_all(self, ids):
        out = {}
        for iid in sorted(ids):
            try:
                img = self.render(iid)
            except (OSError, ValueError) as e:
                self.missing.append(f"{iid}: {e}")
                img = None
            if img is None:
                self.missing.append(iid)
                continue
            ns, path = split_id(iid)
            rel = f"icons/{ns}/{path}.png"
            dst = self.out / rel
            dst.parent.mkdir(parents=True, exist_ok=True)
            img.save(dst)
            out[iid] = rel
        return out


def _tint(img, rgb):
    r, g, b, a = img.split()
    grey = img.convert("L")
    return Image.merge("RGBA", [grey.point(lambda v, c=c: v * c // 255) for c in rgb] + [a])


def iso_cube(faces, tinted=False):
    """32x32 isometric block icon from top/left/right 16x16 face textures."""
    canvas = Image.new("RGBA", (32, 32), (0, 0, 0, 0))
    geometry = {  # origin, u axis, v axis (output pixels per texture pixel)
        "top": ((16, 0), (1, 0.5), (-1, 0.5)),
        "left": ((0, 8), (1, 0.5), (0, 1)),
        "right": ((16, 16), (1, -0.5), (0, 1)),
    }
    shade = {"top": 1.0, "left": 0.8, "right": 0.62}
    for face in ("top", "left", "right"):
        tex = faces.get(face) or faces.get("top") or next(v for v in faces.values() if v is not None)
        if tinted:
            tex = _tint(tex, FOLIAGE)
        (ox, oy), (ux, uy), (vx, vy) = geometry[face]
        det = ux * vy - uy * vx
        # inverse affine: texture coords from output coords
        a, b = vy / det, -vx / det
        d, e = -uy / det, ux / det
        c, f = -(a * ox + b * oy), -(d * ox + e * oy)
        layer = tex.transform((32, 32), Image.AFFINE, (a, b, c, d, e, f), resample=Image.NEAREST,
                              fillcolor=(0, 0, 0, 0))
        if shade[face] != 1.0:
            rgb = ImageEnhance.Brightness(layer.convert("RGB")).enhance(shade[face])
            layer = Image.merge("RGBA", (*rgb.split(), layer.split()[3]))
        canvas = Image.alpha_composite(canvas, layer)
    return canvas