#!/usr/bin/env python3
"""Write OpenMapClassic's `Data/OverlayLand.lua` from the baked `MapOverlayLand` masks.

`cargo run -p benilla-app --example bake_zone_land` writes one 256x256 alpha mask per map, the
union of that map's own `WorldMapOverlay` art -- the shape of the ground it paints. Lua cannot ask
whether a texture file exists (a missing one draws as a white quad, or, as a *mask*, is silently
dropped and the whole rectangle shows), so the addon needs a table of which ids were baked. That
is all this writes.

Run it after the baker, any time the mask set changes:

    python3 scripts/overlay-land-index.py

`--dir` points at another mask folder, `--out` at another destination.
"""
import argparse
import re
import sys
from pathlib import Path

ADDON = Path(__file__).resolve().parent.parent / "benilla-config/AddOns/OpenMapClassic"

HEAD = """--------------------------------------------------------------------------------
-- Which maps have a generated land mask (Media/Textures/MapOverlayLand/<uiMapID>.tga).
--
-- GENERATED -- do not edit. `cargo run -p benilla-app --example bake_zone_land` writes the masks,
-- `scripts/overlay-land-index.py` writes this list.
--
-- Each mask is the union of that map's own `WorldMapOverlay` alpha: the pieces the game reveals
-- as you explore, cut to the shape of the ground, so the union is the map's land and nothing
-- else. `Map/Stitch.lua` cuts the unexplored darkening to it, and falls back to it for the art of
-- any map the hand-made `MapZoneSoft` set has no file for -- this realm has 175 `WorldMapArea`
-- rows against that set's 40.
--
-- A file list, not a file test, because Lua has no way to ask whether a texture exists: a mask
-- whose art is missing is dropped by the engine and the whole rectangle draws, which is the
-- "massive squares" this set exists to remove.
--------------------------------------------------------------------------------

local _, ns = ...

ns.MapOverlayLand = {
"""


def main() -> int:
    ap = argparse.ArgumentParser()
    ap.add_argument("--dir", default=str(ADDON / "Media/Textures/MapOverlayLand"))
    ap.add_argument("--out", default=str(ADDON / "Data/OverlayLand.lua"))
    args = ap.parse_args()

    folder = Path(args.dir)
    if not folder.is_dir():
        print(f"overlay-land-index: no mask folder at {folder}", file=sys.stderr)
        return 1
    ids = sorted(
        int(m.group(1))
        for p in folder.iterdir()
        if (m := re.fullmatch(r"(\d+)\.tga", p.name, re.IGNORECASE))
    )
    if not ids:
        print(f"overlay-land-index: {folder} holds no <id>.tga masks", file=sys.stderr)
        return 1

    body = []
    for i in range(0, len(ids), 8):
        body.append("\t" + " ".join(f"[{n}] = true," for n in ids[i : i + 8]))
    text = HEAD + "\n".join(body) + "\n}\n"
    Path(args.out).write_text(text, encoding="utf-8")
    print(f"overlay-land-index: {len(ids)} masks -> {args.out}")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())