"""Assemble the site: blockout + terrain + street in one file, and pre-check walkability.

    B=/var/lib/flatpak/app/org.blender.Blender/x86_64/stable/active/files
    LD_LIBRARY_PATH="$B/blender/lib" "$B/blender/blender" -b --factory-startup \
      --python Tools/site_assembly.py -- --out Art/blender/site/site-2026-11-06.blend

The three source files are opened/appended, not regenerated. Objects are grouped
into `Site_Blockout`, `Site_Terrain`, and `Site_Street` so the next step — collision
authoring in Unreal — can address them by category.

The walkability check is a pre-check, not the `0.1.0` release check: it raycasts
straight down on a 1 m grid over the walking route (both sidewalks and the
designated crossing) and reports holes (no hit within 5 m) and steps (height jumps
between adjacent samples). Anything that would drop the player is caught here
rather than in the engine.
"""

import argparse
import glob
import math
import os
import shutil
import subprocess
import sys

import bpy

HERE = os.path.dirname(os.path.abspath(__file__))
sys.path.insert(0, os.path.join(HERE, "..", "Geo", "scripts"))
import osm_common as oc  # noqa: E402

ORIGIN_E = 376515.389
ORIGIN_N = 3774224.083


def find_proj():
    env = os.environ.get("PROJ_BIN")
    if env and os.path.exists(env):
        return env
    which = shutil.which("proj")
    if which:
        return which
    matches = sorted(glob.glob(os.path.expanduser(
        "~/.local/share/flatpak/app/org.qgis.qgis/x86_64/stable/*/files/bin/proj")))
    if not matches:
        raise SystemExit("no PROJ binary; set PROJ_BIN")
    return matches[0]


def project_to_local(points, proj_bin):
    """WGS84 (lat, lon) -> project-local X/Y in one PROJ call."""
    app_files = os.path.dirname(os.path.dirname(proj_bin))
    env = dict(os.environ)
    env["LD_LIBRARY_PATH"] = f"{app_files}/lib:{env.get('LD_LIBRARY_PATH', '')}"
    payload = "\n".join(f"{lon:.9f} {lat:.9f}" for lat, lon in points) + "\n"
    out = subprocess.run([proj_bin, "+proj=utm", "+zone=11", "+datum=NAD83", "-f", "%.4f"],
                         input=payload, capture_output=True, text=True, env=env, check=True)
    return [(float(a) - ORIGIN_E, float(b) - ORIGIN_N)
            for a, b in (line.split() for line in out.stdout.strip().splitlines())]


APPEND = {
    "Art/blender/terrain/terrain-2026-11-06.blend": ["Terrain_DEM"],
    "Art/blender/street/street-2026-11-06.blend": [
        "Road_Hollywood", "Sidewalk_South", "Sidewalk_North", "Kerb_South", "Kerb_North",
    ],
}
BLOCKOUT = "Art/blender/blockout/blockout-2026-11-06.blend"


def parse_args():
    argv = sys.argv
    argv = argv[argv.index("--") + 1:] if "--" in argv else []
    ap = argparse.ArgumentParser()
    ap.add_argument("--out", required=True)
    ap.add_argument("--osm", default="Geo/raw/osm-api-map-2026-11-06.osm")
    ap.add_argument("--sample", type=float, default=1.0, help="walkability sample spacing in metres")
    return ap.parse_args(argv)


def collection(name):
    coll = bpy.data.collections.get(name)
    if coll is None:
        coll = bpy.data.collections.new(name)
        bpy.context.scene.collection.children.link(coll)
    return coll


def move_to(obj, coll):
    for parent in list(obj.users_collection):
        parent.objects.unlink(obj)
    coll.objects.link(obj)


def main():
    args = parse_args()
    bpy.ops.wm.open_mainfile(filepath=os.path.abspath(BLOCKOUT))

    for path, names in APPEND.items():
        blend = os.path.abspath(path)
        if not os.path.exists(blend):
            raise SystemExit(f"missing source file: {blend}")
        for name in names:
            bpy.ops.wm.append(
                filepath=f"{blend}/Object/{name}",
                directory=f"{blend}/Object",
                filename=name,
            )

    terrain_coll = collection("Site_Terrain")
    street_coll = collection("Site_Street")
    blockout_coll = collection("Site_Blockout")

    for name in APPEND["Art/blender/street/street-2026-11-06.blend"]:
        obj = bpy.data.objects.get(name)
        if obj and name != "Terrain_DEM":
            move_to(obj, street_coll)
    for name in ("Terrain_DEM",):
        obj = bpy.data.objects.get(name)
        if obj:
            move_to(obj, terrain_coll)
    for obj in list(bpy.data.objects):
        if obj.users_collection and obj.users_collection[0].name.startswith("osm-api-map"):
            move_to(obj, blockout_coll)

    meshes = [o for o in bpy.data.objects if o.type == "MESH"]
    for obj in meshes:
        obj.data.calc_loop_triangles()
    tris = sum(len(o.data.loop_triangles) for o in meshes)
    print(f"site objects: {len(bpy.data.objects)} ({len(meshes)} mesh), "
          f"triangles {tris}, collections: {sorted(c.name for c in bpy.data.collections)}")

    # walkability pre-check
    depsgraph = bpy.context.evaluated_depsgraph_get()
    scene = bpy.context.scene

    block_coll = bpy.data.collections.get("Site_Blockout")
    blockout_names = {o.name for o in block_coll.all_objects} if block_coll else set()
    print(f"walk check ignores {len(blockout_names)} blockout objects (marquees, canopies, roofs)")

    def ground(x, y):
        """Lowest-ish walkable hit: skip building meshes such as marquees overhead."""
        origin_z = 60.0
        for _ in range(8):
            hit, loc, _n, _i, obj, _m = scene.ray_cast(
                depsgraph, (x, y, origin_z), (0.0, 0.0, -1.0), distance=200.0)
            if not hit:
                return None, None
            if obj.name not in blockout_names:
                return loc.z, obj.name
            origin_z = loc.z - 0.02
        return None, None

    nodes, ways = oc.load(os.path.abspath(args.osm))
    line, _lat0, _lon0, _lengths, block_len = oc.block_extent(
        nodes, ways, "Hollywood Boulevard", "North Orange Drive", "North Highland Avenue")

    # route in local metres: both sidewalks and the designated crossing. Points are
    # computed in the mesh frame via PROJ — the OSM spherical approximation is
    # rotated by ~0.75 deg against UTM here, which is metres over a 280 m block.
    lat0 = sum(p[0] for p in line) / len(line)
    lon0 = sum(p[1] for p in line) / len(line)

    def lat_lon(s, offset):
        return oc.point_at(line, _lengths, s, offset, lat0, lon0)

    route_specs = {
        "south sidewalk": [(s, -12.5) for s in [i * args.sample for i in range(int(block_len))]],
        "north sidewalk": [(s, 13.0) for s in [i * args.sample for i in range(int(block_len))]],
        "crossing at 130 m": [(130.0, o) for o in [i * args.sample - 12.5 for i in range(26)]],
    }
    flat = [(spec, lat_lon(s, off)) for spec, samples in route_specs.items() for s, off in samples]
    local = project_to_local([ll for _spec, ll in flat], find_proj())
    routes = {}
    for (spec, _ll), xy in zip(flat, local):
        routes.setdefault(spec, []).append(xy)

    for label, samples in routes.items():
        heights, holes = [], 0
        for x, y in samples:
            z, _hit = ground(x, y)
            if z is None:
                holes += 1
                heights.append(None)
            else:
                heights.append(z)
        deltas = [abs(b - a) for a, b in zip(heights, heights[1:])
                  if a is not None and b is not None]
        max_step = max(deltas) if deltas else float("nan")
        known = [h for h in heights if h is not None]
        print(f"  {label:18} samples {len(heights):3}  holes {holes}  "
              f"Z {min(known):+.2f}..{max(known):+.2f}  max step {max_step*100:.1f} cm")

    out = os.path.abspath(args.out)
    os.makedirs(os.path.dirname(out), exist_ok=True)
    bpy.ops.wm.save_as_mainfile(filepath=out)
    print(f"saved {out}")


if __name__ == "__main__":
    main()