#!/usr/bin/env python3
"""Generate mods/worldmap-reveal-data.lua from the client's world map DBCs.

The Reveal World Map module needs the overlays of every zone, but the game
only reports the ones a character has already explored. This script reads the
complete list from DBFilesClient\\WorldMapArea.dbc and
DBFilesClient\\WorldMapOverlay.dbc and writes it as a Lua table.

Extract both files from the highest-priority client MPQ that contains them
(any MPQ tool will do), then run:

    python gen-worldmap-reveal-data.py WorldMapArea.dbc WorldMapOverlay.dbc [out.lua]

The output defaults to ../mods/worldmap-reveal-data.lua. Run it again whenever
a client patch ships a new WorldMapOverlay.dbc.
"""
import hashlib
import struct
import sys
from pathlib import Path

# 1.12 layouts: WorldMapArea = id, map, area, name, 4 bounds (8 fields);
# WorldMapOverlay = id, mapArea, area[4], mapPointX, mapPointY, textureName,
# width, height, offsetX, offsetY, hitRect[4] (17 fields)
AREA_FIELDS, AREA_NAME = 8, 3
OVERLAY_FIELDS = 17
OV_AREA, OV_TEXTURE, OV_WIDTH, OV_HEIGHT, OV_X, OV_Y = 1, 8, 9, 10, 11, 12


def read_dbc(path, fields):
    raw = Path(path).read_bytes()
    magic, count, nfields, size, _ = struct.unpack_from("<4s4I", raw, 0)
    if magic != b"WDBC" or nfields != fields or size != fields * 4:
        sys.exit(f"{path}: expected a WDBC file with {fields} fields, got {magic!r} {nfields} fields")
    strings = raw[20 + count * size:]

    def string(offset):
        return strings[offset:strings.index(b"\0", offset)].decode("utf-8")

    rows = [struct.unpack_from(f"<{fields}I", raw, 20 + i * size) for i in range(count)]
    return rows, string, hashlib.sha1(raw).hexdigest()


def lua_string(text):
    return '"' + text.replace("\\", "\\\\").replace('"', '\\"') + '"'


def main():
    if len(sys.argv) not in (3, 4):
        sys.exit(__doc__)
    out = Path(sys.argv[3]) if len(sys.argv) == 4 else Path(__file__).resolve().parent.parent / "mods" / "worldmap-reveal-data.lua"

    areas, area_string, area_sha = read_dbc(sys.argv[1], AREA_FIELDS)
    overlays, overlay_string, overlay_sha = read_dbc(sys.argv[2], OVERLAY_FIELDS)
    zone_of = {row[0]: area_string(row[AREA_NAME]) for row in areas}

    zones, skipped = {}, 0
    for row in sorted(overlays):
        zone = zone_of.get(row[OV_AREA], "")
        texture = overlay_string(row[OV_TEXTURE])
        if not zone or not texture or not row[OV_WIDTH] or not row[OV_HEIGHT]:
            skipped += 1
            continue
        geometry = ":".join(str(row[i]) for i in (OV_WIDTH, OV_HEIGHT, OV_X, OV_Y))
        zones.setdefault(zone, []).append(f"{texture}:{geometry}")

    lines = [
        "-- Generated by tools/gen-worldmap-reveal-data.py, do not edit by hand.",
        f"-- WorldMapArea.dbc sha1 {area_sha}",
        f"-- WorldMapOverlay.dbc sha1 {overlay_sha}",
        "ShaguTweaks.MapOverlayDataOctoWoW = {",
    ]
    for zone in sorted(zones, key=str.lower):
        entries = ", ".join(lua_string(entry) for entry in zones[zone])
        lines.append(f"  [{lua_string(zone)}] = {{ {entries}, }},")
    lines.append("}")
    out.write_text("\n".join(lines) + "\n", encoding="utf-8", newline="\n")

    total = sum(len(v) for v in zones.values())
    print(f"{out}: {len(zones)} zones, {total} overlays, {skipped} rows skipped")


if __name__ == "__main__":
    main()