"""Material assignment helpers for Blender headless renders."""
from __future__ import annotations

import os
import re as _re
import time as _time

FAILED_MATERIAL_NAME = "SCHAEFFLER_059999_FailedMaterial"


def _find_material_with_nodes(base_name: str):
    """Find a material by name that actually has shader nodes.

    Blender's USD importer creates empty stub materials (use_nodes=True,
    node_tree has 0 nodes) from USD material bindings.  When we later
    append the real material from a .blend library, Blender renames it
    with a .001/.002 suffix to avoid the name collision.

    This helper searches bpy.data.materials for the version that has
    actual shader nodes, preferring exact name match, then .NNN suffixes.
    """
    import bpy  # type: ignore[import]

    # Exact name first
    exact = bpy.data.materials.get(base_name)
    if exact and exact.node_tree and len(exact.node_tree.nodes) > 0:
        return exact

    # Search for .NNN suffixed versions
    for mat in bpy.data.materials:
        if not mat.name.startswith(base_name):
            continue
        suffix = mat.name[len(base_name):]
        if suffix == "" or _re.match(r'^\.\d{3}$', suffix):
            if mat.node_tree and len(mat.node_tree.nodes) > 0:
                return mat
    return None


def _batch_append_materials(mat_lib_path: str, names: set[str]) -> dict:
    """Append multiple materials from a .blend file in a single open.

    Uses bpy.data.libraries.load() to open the .blend once instead of
    N separate bpy.ops.wm.append() calls (each reopens the file).
    Falls back to individual append for any materials that fail to load.

    Handles empty material stubs left by Blender's USD importer: when a
    stub exists with the target name, the library material gets renamed
    with a .NNN suffix.  We find it via _find_material_with_nodes().
    """
    import bpy  # type: ignore[import]

    result: dict = {}
    if not names:
        return result

    try:
        with bpy.data.libraries.load(mat_lib_path, link=False) as (data_from, data_to):
            # data_from.materials lists all material names in the .blend
            available = set(data_from.materials)
            to_load = [n for n in names if n in available]
            not_found = names - available
            data_to.materials = to_load
        # After the context manager closes, materials are loaded into bpy.data.
        # If a USD stub occupied the name, the real material gets a .NNN suffix.
        for mat_name in to_load:
            mat = _find_material_with_nodes(mat_name)
            if mat:
                result[mat_name] = mat
                if mat.name != mat_name:
                    print(f"[blender_render] batch-appended material: {mat_name} (as '{mat.name}', stub collision)")
                else:
                    print(f"[blender_render] batch-appended material: {mat_name}")
            else:
                print(f"[blender_render] WARNING: material '{mat_name}' not found after batch append")
        if not_found:
            print(f"[blender_render] WARNING: materials not in library: {sorted(not_found)[:10]}")
    except Exception as exc:
        print(f"[blender_render] WARNING: batch append failed ({exc}), falling back to individual append")
        # Fallback: individual append for each material
        for mat_name in names:
            if mat_name in result:
                continue
            try:
                bpy.ops.wm.append(
                    filepath=f"{mat_lib_path}/Material/{mat_name}",
                    directory=f"{mat_lib_path}/Material/",
                    filename=mat_name,
                    link=False,
                )
                mat = _find_material_with_nodes(mat_name)
                if mat:
                    result[mat_name] = mat
            except Exception:
                pass

    return result


def assign_failed_material(part_obj) -> None:
    """Assign the standard fallback material (magenta) when no library material matches.

    Reuses SCHAEFFLER_059999_FailedMaterial if already loaded; otherwise
    creates a simple magenta Principled BSDF node tree.
    """
    import bpy  # type: ignore[import]

    mat = bpy.data.materials.get(FAILED_MATERIAL_NAME)
    if mat is None:
        mat = bpy.data.materials.new(name=FAILED_MATERIAL_NAME)
        mat.use_nodes = True
        bsdf = mat.node_tree.nodes.get("Principled BSDF")
        if bsdf:
            bsdf.inputs["Base Color"].default_value = (1.0, 0.0, 1.0, 1.0)  # magenta
            bsdf.inputs["Roughness"].default_value = 0.6
    part_obj.data.materials.clear()
    part_obj.data.materials.append(mat)


def build_mat_map_lower(material_map: dict) -> dict:
    """Return a lowercased version of material_map with _AF\\d+ suffix variants added.

    Both the original key and the AF-stripped key are inserted so that GLB
    object names (which may lack _AF suffixes that OCC adds to mat_map keys)
    can match in either direction.
    """
    mat_map_lower: dict = {}
    for k, v in material_map.items():
        kl = k.lower().strip()
        mat_map_lower[kl] = v
        # USD path: part_key slugs replace ALL non-alphanumeric chars with '_'
        # (same regex as generate_part_key in export_step_to_usd.py).
        # E.g. "F-802007_TR4-D1" → "f_802007_tr4_d1".  Add slug variant so
        # hyphenated OCC names match USD-imported Blender objects.
        slug_key = _re.sub(r'[^a-z0-9]+', '_', kl).strip('_')
        if slug_key and slug_key != kl:
            mat_map_lower.setdefault(slug_key, v)
        # Strip OCC assembly-frame suffixes: _AF0, _AF0_1, _AF0_1_AF0, etc.
        # Pattern matches one or more groups of _AF<n> optionally followed by
        # an instance number _<n>, anchored at end of string.
        stripped = _re.sub(r'(_af\d+(_\d+)?)+$', '', kl)
        if stripped != kl:
            mat_map_lower.setdefault(stripped, v)
            # Also slug the AF-stripped key for USD path where part_key is
            # both AF-stripped AND slugified (e.g. "ge360-hf_..." → "ge360_hf_...")
            slug_stripped = _re.sub(r'[^a-z0-9]+', '_', stripped).strip('_')
            if slug_stripped and slug_stripped != stripped:
                mat_map_lower.setdefault(slug_stripped, v)
    return mat_map_lower


def apply_material_library_direct(
    parts: list,
    mat_lib_path: str,
    material_lookup: dict[str, str],
) -> None:
    """Assign materials from library using a direct object_name → material_name mapping.

    This bypasses all name-matching heuristics — the mapping comes from USD
    customData (schaeffler:canonicalMaterialName) read via pxr after Blender import.
    Parts not present in material_lookup receive FAILED_MATERIAL_NAME.

    material_lookup: {blender_object_name: canonical_material_name}
    """
    if not mat_lib_path or not os.path.isfile(mat_lib_path):
        print(f"[blender_render] material library not found: {mat_lib_path}")
        return

    import bpy  # type: ignore[import]

    _t0 = _time.monotonic()

    # Collect unique material names needed
    needed = set(material_lookup.values())
    if not needed:
        return

    # Batch-append materials from library (single file open)
    appended: dict = {}
    _t_append = _time.monotonic()
    # Check already-loaded materials first — but skip empty stubs created by
    # Blender's USD importer (use_nodes=True but node_tree has 0 nodes).
    # Those stubs must be loaded from the library via _batch_append_materials
    # which uses _find_material_with_nodes() to resolve stub collisions.
    still_needed = set()
    for mat_name in needed:
        existing = _find_material_with_nodes(mat_name)
        if existing:
            appended[mat_name] = existing
        else:
            still_needed.add(mat_name)
    # Load remaining from .blend in one pass
    if still_needed:
        appended.update(_batch_append_materials(mat_lib_path, still_needed))
    _append_dur = _time.monotonic() - _t_append
    print(f"[blender_render] TIMING material_append_direct={_append_dur:.2f}s ({len(appended)}/{len(needed)} materials)", flush=True)

    if not appended:
        return

    assigned_count = 0
    unmatched_names = []
    for part in parts:
        mat_name = material_lookup.get(part.name)
        if mat_name and mat_name in appended:
            if part.data.users > 1:
                part.data = part.data.copy()
            part.data.materials.clear()
            part.data.materials.append(appended[mat_name])
            assigned_count += 1
        else:
            unmatched_names.append(part.name)

    _assign_dur = _time.monotonic() - _t_append - _append_dur + (_time.monotonic() - _t0 - _append_dur)
    _total = _time.monotonic() - _t0
    print(f"[blender_render] TIMING material_assign_direct={_total:.2f}s "
          f"(append={_append_dur:.2f}s, assign={_total - _append_dur:.2f}s, "
          f"{assigned_count}/{len(parts)} matched)", flush=True)
    if unmatched_names:
        print(f"[blender_render] unmatched (no primvar): {unmatched_names[:10]}", flush=True)
        for part in parts:
            if part.name in set(unmatched_names):
                if part.data.users > 1:
                    part.data = part.data.copy()
                assign_failed_material(part)


def apply_material_library(
    parts: list,
    mat_lib_path: str,
    mat_map: dict,
    part_names_ordered: list | None = None,
) -> None:
    """Append materials from library .blend and assign to parts via material_map.

    GLB-imported objects are named after STEP parts, so matching is by name
    (stripping Blender .NNN suffix for duplicates). Falls back to
    part_names_ordered index-based matching.

    mat_map: {part_name_lower: material_name}
    Parts without a match receive the FAILED_MATERIAL_NAME sentinel.
    """
    if not mat_lib_path or not os.path.isfile(mat_lib_path):
        print(f"[blender_render] material library not found: {mat_lib_path}")
        return

    import bpy  # type: ignore[import]

    _t0 = _time.monotonic()

    if part_names_ordered is None:
        part_names_ordered = []

    # Collect unique material names needed
    needed = set(mat_map.values())
    if not needed:
        return

    # Batch-append materials from library (single file open)
    appended: dict = {}
    _t_append = _time.monotonic()
    appended.update(_batch_append_materials(mat_lib_path, needed))
    _append_dur = _time.monotonic() - _t_append
    print(f"[blender_render] TIMING material_append={_append_dur:.2f}s ({len(appended)}/{len(needed)} materials)", flush=True)

    if not appended:
        return

    # Assign materials to parts — primary: name-based (GLB object names),
    # secondary: index-based via part_names_ordered
    assigned_count = 0
    unmatched_names = []
    for i, part in enumerate(parts):
        # Try name-based matching first (strip Blender .NNN suffix)
        base_name = _re.sub(r'\.\d{3}$', '', part.name)
        # Strip OCC assembly-instance suffix (_AF0, _AF1, …) — GLB object
        # names may or may not have them while mat_map keys might.
        _prev = None
        while _prev != base_name:
            _prev = base_name
            base_name = _re.sub(r'_AF\d+$', '', base_name, flags=_re.IGNORECASE)
        part_key = base_name.lower().strip()
        mat_name = mat_map.get(part_key)

        # Prefix fallback: if a mat_map key starts with our base name or
        # vice-versa, use the longest matching key (most-specific wins).
        if not mat_name:
            for key, val in sorted(mat_map.items(), key=lambda x: len(x[0]), reverse=True):
                if len(key) >= 5 and len(part_key) >= 5 and (
                    part_key.startswith(key) or key.startswith(part_key)
                ):
                    mat_name = val
                    break

        # Fall back to index-based matching via part_names_ordered
        if not mat_name and part_names_ordered and i < len(part_names_ordered):
            step_name = part_names_ordered[i]
            step_key = step_name.lower().strip()
            mat_name = mat_map.get(step_key)
            # Also try stripping AF from part_names_ordered entry
            if not mat_name:
                _p2 = None
                while _p2 != step_key:
                    _p2 = step_key
                    step_key = _re.sub(r'_af\d+$', '', step_key)
                mat_name = mat_map.get(step_key)

        if mat_name and mat_name in appended:
            part.data.materials.clear()
            part.data.materials.append(appended[mat_name])
            assigned_count += 1
        else:
            unmatched_names.append(part.name)

    _total = _time.monotonic() - _t0
    print(f"[blender_render] TIMING material_assign={_total:.2f}s "
          f"(append={_append_dur:.2f}s, match={_total - _append_dur:.2f}s, "
          f"{assigned_count}/{len(parts)} matched)", flush=True)
    if unmatched_names:
        print(f"[blender_render] unmatched parts → assigning {FAILED_MATERIAL_NAME}: {unmatched_names[:10]}", flush=True)
        unmatched_set = set(unmatched_names)
        for part in parts:
            if part.name in unmatched_set:
                if part.data.users > 1:
                    part.data = part.data.copy()
                assign_failed_material(part)