"""Render a Solution to a PNG image.

The renderer draws a grid mirroring the in-game inventory: each cell is a
fixed-size square; cells with slabs show the slab image (downloaded from the
CDN on first run and cached locally). Effect numbers from `compute_effects`
are overlaid on each cell.
"""

from __future__ import annotations

import os
from io import BytesIO
from typing import Dict, Optional

from PIL import Image, ImageDraw, ImageFont

from .slabs import (
    GRID_COLS,
    Placement,
    SLABS_BY_VALUE,
    compute_effects,
)
from .solver import Solution


CACHE_DIR = os.path.join(
    os.environ.get("LOCALAPPDATA")
    or os.environ.get("XDG_CACHE_HOME")
    or os.path.expanduser("~/.cache"),
    "sephiria_inv",
    "slabs",
)

CDN_BASE = "https://img.sephiria.wiki"

CELL = 96  # pixels per slot
PAD = 12
HEADER = 56
FOOTER = 40

BG_COLOR = (29, 16, 27)
CELL_BG = (50, 30, 50)
CELL_BORDER = (88, 60, 90)
POS_COLOR = (132, 220, 132)
NEG_COLOR = (240, 110, 110)
ZERO_COLOR = (160, 160, 160)
IGNORE_COLOR = (160, 160, 160)
TEXT_COLOR = (236, 226, 232)


# ---------------------------------------------------------------------------
# Asset cache
# ---------------------------------------------------------------------------


def _ensure_cache_dir() -> None:
    os.makedirs(CACHE_DIR, exist_ok=True)


def _local_path(slab_image: str) -> str:
    # slab.image is like "slabs/foo.png"; flatten to filename
    return os.path.join(CACHE_DIR, os.path.basename(slab_image))


def _fetch_image(rel_or_url: str, timeout: float = 10.0) -> Optional[Image.Image]:
    """Fetch an image from the CDN. Accepts a full URL or a 'slabs/foo.png' path."""
    _ensure_cache_dir()
    path = _local_path(rel_or_url)
    if os.path.exists(path):
        try:
            return Image.open(path).convert("RGBA")
        except Exception:
            pass
    try:
        import requests
        url = rel_or_url if rel_or_url.startswith("http") else f"{CDN_BASE}/{rel_or_url.lstrip('/')}"
        r = requests.get(url, timeout=timeout)
        if r.status_code != 200:
            return None
        with open(path, "wb") as f:
            f.write(r.content)
        return Image.open(BytesIO(r.content)).convert("RGBA")
    except Exception:
        return None


def fetch_slab_image(slab_image: str, timeout: float = 10.0) -> Optional[Image.Image]:
    """Return a PIL Image for the slab. Caches under CACHE_DIR."""
    return _fetch_image(slab_image, timeout=timeout)


def fetch_artifact_image(url: str, timeout: float = 10.0) -> Optional[Image.Image]:
    """Return a PIL Image for an artifact (full URL from artifacts.json)."""
    return _fetch_image(url, timeout=timeout)


# ---------------------------------------------------------------------------
# Font
# ---------------------------------------------------------------------------


def _load_font(size: int) -> ImageFont.ImageFont:
    candidates = [
        "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",
        "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
        "/usr/share/fonts/TTF/DejaVuSans-Bold.ttf",
        "C:\\Windows\\Fonts\\malgun.ttf",
        "C:\\Windows\\Fonts\\arial.ttf",
        "/System/Library/Fonts/Helvetica.ttc",
    ]
    for c in candidates:
        if os.path.exists(c):
            try:
                return ImageFont.truetype(c, size)
            except Exception:
                continue
    return ImageFont.load_default()


# ---------------------------------------------------------------------------
# Public API
# ---------------------------------------------------------------------------


def render_solution(
    sol: Solution,
    *,
    download: bool = True,
    title: Optional[str] = None,
) -> Image.Image:
    """Render the solution to a PIL Image."""
    grid = sol.grid
    rows = len(grid)
    width = PAD * 2 + GRID_COLS * CELL
    height = PAD * 2 + HEADER + rows * CELL + FOOTER

    img = Image.new("RGB", (width, height), BG_COLOR)
    draw = ImageDraw.Draw(img)

    title_font = _load_font(22)
    cell_font = _load_font(20)
    eff_font = _load_font(28)
    foot_font = _load_font(16)

    # Title
    txt = title or "Sephiria Inventory Optimizer"
    draw.text((PAD, PAD), txt, fill=TEXT_COLOR, font=title_font)
    draw.text(
        (PAD, PAD + 26),
        f"slots {sol.slot_num} · placed {len(sol.placements)} · score {sol.score}",
        fill=(180, 180, 180),
        font=foot_font,
    )

    # Effects map
    effects, flags = compute_effects(sol.placements, grid)
    by_slot: Dict[str, Placement] = {p.slot_id: p for p in sol.placements}

    grid_top = PAD + HEADER
    for row_cfg in grid:
        y = row_cfg["rows"]
        for x in range(row_cfg["cols"]):
            cx0 = PAD + x * CELL
            cy0 = grid_top + y * CELL
            cx1 = cx0 + CELL - 4
            cy1 = cy0 + CELL - 4
            # cell background
            draw.rounded_rectangle(
                (cx0, cy0, cx1, cy1), radius=8, fill=CELL_BG, outline=CELL_BORDER
            )

            slot_id = f"{y}-{x}"
            p = by_slot.get(slot_id)
            if p is not None:
                slab = SLABS_BY_VALUE.get(p.value)
                placed = False
                if slab is not None and download:
                    img_s = fetch_slab_image(slab.image)
                    if img_s is not None:
                        img_s = img_s.resize((CELL - 16, CELL - 16))
                        if p.rotation:
                            # PIL rotates counter-clockwise; sephiria rotation
                            # is 90°-CW per step.
                            img_s = img_s.rotate(-90 * p.rotation, expand=False)
                        img.paste(img_s, (cx0 + 6, cy0 + 6), img_s)
                        placed = True
                if not placed and slab is not None:
                    # text fallback
                    draw.text(
                        (cx0 + 6, cy0 + 6),
                        slab.ko_label,
                        fill=TEXT_COLOR,
                        font=cell_font,
                    )

                # effect overlay (top-right)
                v = effects.get(slot_id, 0)
                if flags.get(slot_id) == "ignore":
                    label = "—"
                    color = IGNORE_COLOR
                else:
                    label = f"{v:+d}" if v else "0"
                    color = (
                        POS_COLOR if v > 0 else NEG_COLOR if v < 0 else ZERO_COLOR
                    )
                tw = draw.textlength(label, font=eff_font)
                draw.text(
                    (cx1 - tw - 6, cy0 + 4),
                    label,
                    fill=color,
                    font=eff_font,
                )

    # Footer
    draw.text(
        (PAD, height - FOOTER + 8),
        "Generated by sephiria_inv_program · data from img.sephiria.wiki",
        fill=(120, 120, 120),
        font=foot_font,
    )

    return img


def save_solution(sol: Solution, out_path: str, **kwargs) -> str:
    img = render_solution(sol, **kwargs)
    img.save(out_path)
    return out_path