"""Procedural pixel-art sprites for plants and the app favicon.

Each sprite is built from a 16x16 grid: a 10-row plant "archetype" stacked on
top of a 6-row pot. Rows are authored as 8-character halves and mirrored
(`half + half[::-1]`) to get a symmetric 16-wide row, then the whole grid is
upscaled with nearest-neighbour resizing for a crisp pixel-art look.
"""

import functools
from pathlib import Path

import pandas as pd
from PIL import Image

GROWTH_CSV = "data/growth_csv/growth_ds.csv"
STATIC_DIR = Path("static")
SPRITES_DIR = STATIC_DIR / "sprites"
FAVICON_PATH = STATIC_DIR / "favicon.png"

# ── Palette ──────────────────────────────────────────────────────────────────
PALETTE = {
    ".": (0, 0, 0, 0),
    "G": (46, 125, 50, 255),    # dark leaf green
    "g": (102, 187, 106, 255),  # mid green
    "l": (197, 225, 165, 255),  # light green / highlight
    "y": (255, 213, 79, 255),   # yellow flower
    "o": (255, 152, 0, 255),    # orange flower center
    "t": (121, 85, 72, 255),    # trunk brown
    "S": (109, 76, 65, 255),    # soil
}

POT_STYLES = {
    "terracotta":   {"P": (216, 124, 90, 255), "Q": (173, 96, 68, 255),  "R": (235, 165, 138, 255)},
    "white":        {"P": (245, 245, 245, 255), "Q": (210, 210, 210, 255), "R": (255, 255, 255, 255)},
    "ceramic_blue": {"P": (84, 153, 199, 255), "Q": (55, 109, 148, 255), "R": (165, 214, 237, 255)},
    "charcoal":     {"P": (74, 74, 74, 255),   "Q": (45, 45, 45, 255),   "R": (115, 115, 115, 255)},
}
POT_NAMES = list(POT_STYLES.keys())

# ── Plant archetypes (10 half-rows, 8 chars each) ───────────────────────────
PLANT_SPRITES = {
    "cactus": [
        "........",
        "........",
        "......gg",
        "......gG",
        "..gg..gG",
        "..gG..gG",
        "..gg..gG",
        "......gG",
        "......gg",
        "......gl",
    ],
    "succulent": [
        "........",
        ".......l",
        "......gl",
        ".....Ggl",
        "....gGgl",
        "...ggGgl",
        "..gggGgl",
        ".ggggGgl",
        "ggggggGl",
        "gggggggl",
    ],
    "fern": [
        "........",
        "...gGg..",
        "..glGgl.",
        ".gGglGg.",
        "gGlgGgl.",
        "gglGglg.",
        ".gGlGg..",
        "...g.g..",
        "....g...",
        "....gg..",
    ],
    "flower": [
        "......y.",
        ".....yoy",
        "......y.",
        ".......g",
        "..g....g",
        ".gG....g",
        "..g....g",
        ".......g",
        ".......g",
        "......gg",
    ],
    "palm": [
        "..l...l.",
        ".gg...gg",
        "..gGGg..",
        "...g.g..",
        ".......t",
        ".......t",
        ".......t",
        ".......t",
        "......tt",
        "......tt",
    ],
    "trailing": [
        "........",
        ".gGggGl.",
        "gGggGgl.",
        "Gggggl..",
        "gl......",
        "Gl......",
        "gl......",
        "Gl......",
        "gl......",
        "gl......",
    ],
}
ARCHETYPES = list(PLANT_SPRITES.keys())

# ── Pot (6 half-rows, 8 chars each) ─────────────────────────────────────────
POT_BASE = [
    "...SSSSS",
    "..RPPPPP",
    "..QPPPPP",
    "...QPPPP",
    "....QPPP",
    ".....QPP",
]


# ── Genus -> (archetype, pot) mapping ───────────────────────────────────────
@functools.lru_cache(maxsize=1)
def _growth_table() -> pd.DataFrame:
    return pd.read_csv(GROWTH_CSV)


def _stable_hash(text: str) -> int:
    """Deterministic hash (stable across runs, unlike builtin hash() for str)."""
    h = 0
    for ch in text:
        h = (h * 31 + ord(ch)) & 0xFFFFFFFF
    return h


def genus_to_sprite_key(genus: str) -> tuple[str, str]:
    """Map a genus to a deterministic (plant archetype, pot style) pair."""
    df = _growth_table()
    row = df[df["Genus"] == genus]

    if row.empty:
        h = _stable_hash(genus)
        archetype = ARCHETYPES[h % len(ARCHETYPES)]
        pot = POT_NAMES[(h // len(ARCHETYPES)) % len(POT_NAMES)]
        return archetype, pot

    growth = str(row["Growth"].iloc[0]).lower()
    soil = str(row["Soil"].iloc[0]).lower()
    sunlight = str(row["Sunlight"].iloc[0]).lower()

    if "sandy" in soil and "full" in sunlight:
        archetype = "cactus" if growth == "slow" else "succulent"
    elif "indirect" in sunlight and growth in ("slow", "moderate"):
        archetype = "fern" if ("well-drained" in soil or "loamy" in soil) else "trailing"
    elif growth == "fast" and "full" in sunlight:
        archetype = "flower"
    elif growth == "slow" and "well-drained" in soil:
        archetype = "palm"
    else:
        archetype = "fern"

    pot = {"sandy": "terracotta", "well-drained": "white", "loamy": "charcoal"}.get(soil, "ceramic_blue")
    return archetype, pot


# ── Rendering ────────────────────────────────────────────────────────────────
def _build_image(half_rows: list[str], palette: dict) -> Image.Image:
    rows = [half + half[::-1] for half in half_rows]
    size = len(rows)
    img = Image.new("RGBA", (size, size), (0, 0, 0, 0))
    for y, row in enumerate(rows):
        for x, ch in enumerate(row):
            img.putpixel((x, y), palette.get(ch, (0, 0, 0, 0)))
    return img


def render_sprite(genus: str, scale: int = 8) -> Image.Image:
    """Render the pixel-art (plant + pot) sprite for a genus."""
    archetype, pot_style = genus_to_sprite_key(genus)
    half_rows = PLANT_SPRITES[archetype] + POT_BASE
    palette = {**PALETTE, **POT_STYLES[pot_style]}
    img = _build_image(half_rows, palette)
    return img.resize((img.width * scale, img.height * scale), Image.NEAREST)


def _slugify(genus: str) -> str:
    return "".join(ch.lower() if ch.isalnum() else "_" for ch in genus)


def get_sprite_path(genus: str) -> str:
    """Return the path to the (lazily rendered + cached) sprite for a genus."""
    SPRITES_DIR.mkdir(parents=True, exist_ok=True)
    path = SPRITES_DIR / f"{_slugify(genus)}.png"
    if not path.exists():
        render_sprite(genus).save(path)
    return str(path)


def ensure_favicon() -> str:
    """Return the path to the (lazily rendered + cached) app favicon."""
    STATIC_DIR.mkdir(parents=True, exist_ok=True)
    if not FAVICON_PATH.exists():
        half_rows = PLANT_SPRITES["fern"] + POT_BASE
        palette = {**PALETTE, **POT_STYLES["terracotta"]}
        img = _build_image(half_rows, palette)
        img = img.resize((img.width * 4, img.height * 4), Image.NEAREST)
        img.save(FAVICON_PATH)
    return str(FAVICON_PATH)