"""Generate the social-share card (Open Graph / Twitter image), 1200x630.

Run once; the PNG is committed to static/ and copied to the site root at build
time. The container does not need Pillow at runtime. Re-run only if the wording
or brand colours change:  python generate_og.py
"""
from __future__ import annotations

import os

from PIL import Image, ImageDraw, ImageFont

from generate_icons import make_icon

STATIC_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "static")
W, H, SS = 1200, 630, 2  # final size + supersample factor for crisp text

INK = (33, 37, 41)
GREY = (90, 99, 110)
GREEN = (26, 152, 80)
# Price legend gradient (matches the map): cheap green -> pricey red.
LEGEND = [(26, 152, 80), (145, 207, 96), (254, 224, 139), (252, 141, 89), (215, 48, 39)]

# Font candidates per weight: Arial on macOS (local), DejaVu in the container.
FONTS = {
    "bold": ["/System/Library/Fonts/Supplemental/Arial Bold.ttf",
             "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",
             "/Library/Fonts/Arial Bold.ttf"],
    "regular": ["/System/Library/Fonts/Supplemental/Arial.ttf",
                "/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
                "/Library/Fonts/Arial.ttf"],
}


def _font(weight: str, size: int) -> ImageFont.FreeTypeFont:
    for path in FONTS[weight]:
        if os.path.exists(path):
            return ImageFont.truetype(path, size)
    return ImageFont.load_default()


def _lerp(a, b, t):
    return tuple(round(a[i] + (b[i] - a[i]) * t) for i in range(3))


def _gradient_bar(draw: ImageDraw.ImageDraw, x0, y0, x1, y1) -> None:
    """Horizontal multi-stop gradient bar (the price scale)."""
    span = x1 - x0
    seg = span / (len(LEGEND) - 1)
    for x in range(x0, x1):
        f = (x - x0) / seg
        i = min(int(f), len(LEGEND) - 2)
        draw.line([(x, y0), (x, y1)], fill=_lerp(LEGEND[i], LEGEND[i + 1], f - i))


def build() -> Image.Image:
    w, h = W * SS, H * SS
    img = Image.new("RGB", (w, h), (255, 255, 255))
    d = ImageDraw.Draw(img)

    # Left: the brand icon tile.
    icon = make_icon(360 * SS, rounded=True)
    img.paste(icon, (70 * SS, (h - icon.height) // 2), icon)

    tx = 470 * SS  # text column
    d.text((tx, 160 * SS), "Prix des carburants", font=_font("bold", 60 * SS), fill=INK)
    d.text((tx, 240 * SS), "en France", font=_font("bold", 60 * SS), fill=GREEN)
    d.text((tx, 350 * SS), "Carte en temps réel — gazole, SP95,",
           font=_font("regular", 34 * SS), fill=GREY)
    d.text((tx, 396 * SS), "SP98, E85, GPL & bornes de recharge",
           font=_font("regular", 34 * SS), fill=GREY)

    _gradient_bar(d, tx, 470 * SS, (W - 80) * SS, 492 * SS)
    d.text((tx, 504 * SS), "moins cher", font=_font("regular", 26 * SS), fill=GREY)
    pricey = "plus cher"
    pf = _font("regular", 26 * SS)
    d.text(((W - 80) * SS - d.textlength(pricey, font=pf), 504 * SS), pricey, font=pf, fill=GREY)

    d.text((tx, 556 * SS), "samdnx-prix-carburant.hf.space",
           font=_font("bold", 26 * SS), fill=GREEN)

    return img.resize((W, H), Image.LANCZOS)


def save(path: str) -> None:
    """Render the card and write it to path (used at build time)."""
    build().save(path, optimize=True)


def main() -> None:
    os.makedirs(STATIC_DIR, exist_ok=True)
    out = os.path.join(STATIC_DIR, "og-card.png")
    save(out)
    print("wrote", out, f"({os.path.getsize(out) // 1024} KB)")


if __name__ == "__main__":
    main()