#!/usr/bin/env python3
import hashlib
import json
import os
import pathlib
import shutil
import sys
import tempfile

import bpy


ARMATURE_NAME = "WebGapArmatureAlignArmature"
OBJECT_NAME = "WebGapArmatureAlignObject"
PARENT_NAME = "WebGapArmatureAlignParent"
CHILD_NAME = "WebGapArmatureAlignChild"


def vector(value):
    return [round(float(component), 6) for component in value]


def state_report():
    armature = bpy.data.armatures.get(ARMATURE_NAME)
    obj = bpy.data.objects.get(OBJECT_NAME)
    if armature is None or obj is None or obj.type != "ARMATURE" or obj.data != armature:
        raise RuntimeError("armature.align fixture is missing")
    bones = []
    for bone in armature.bones:
        bones.append({
            "name": bone.name,
            "parent": bone.parent.name if bone.parent else None,
            "head": vector(bone.head_local),
            "tail": vector(bone.tail_local),
        })
    bones.sort(key=lambda value: value["name"])
    return {"object": OBJECT_NAME, "armature": ARMATURE_NAME, "bones": bones}


def axes_aligned(state):
    parent = next(bone for bone in state["bones"] if bone["name"] == PARENT_NAME)
    child = next(bone for bone in state["bones"] if bone["name"] == CHILD_NAME)
    axis = [parent["tail"][index] - parent["head"][index] for index in range(3)]
    child_axis = [child["tail"][index] - child["head"][index] for index in range(3)]
    cross = [axis[1] * child_axis[2] - axis[2] * child_axis[1], axis[2] * child_axis[0] - axis[0] * child_axis[2], axis[0] * child_axis[1] - axis[1] * child_axis[0]]
    return max(abs(value) for value in cross) <= 1e-5


def run_operator():
    bpy.context.view_layer.objects.active = bpy.data.objects[OBJECT_NAME]
    bpy.data.objects[OBJECT_NAME].select_set(True)
    if bpy.context.object.mode != "EDIT":
        bpy.ops.object.mode_set(mode="EDIT")
    armature = bpy.data.armatures[ARMATURE_NAME]
    parent = armature.edit_bones[PARENT_NAME]
    child = armature.edit_bones[CHILD_NAME]
    parent.select = True
    child.select = True
    armature.bones.active = armature.bones[PARENT_NAME]
    poll = bool(bpy.ops.armature.align.poll())
    if not poll:
        raise RuntimeError("ARMATURE_OT_align poll failed")
    result = bpy.ops.armature.align()
    if result != {"FINISHED"}:
        raise RuntimeError(f"ARMATURE_OT_align returned {result}")
    bpy.ops.object.mode_set(mode="OBJECT")
    return poll, result


def main():
    arguments = sys.argv[sys.argv.index("--") + 1 :]
    if len(arguments) != 2:
        raise SystemExit("usage: blender -b --factory-startup --python check-action-armature-align-desktop.py -- FIXTURE REPORT")
    fixture, output = (pathlib.Path(value).resolve() for value in arguments)
    bpy.ops.wm.open_mainfile(filepath=str(fixture), load_ui=False)
    before = state_report()
    before_child = next(bone for bone in before["bones"] if bone["name"] == CHILD_NAME)
    poll, _result = run_operator()
    after = state_report()
    already_aligned = axes_aligned(before)
    parent = next(bone for bone in after["bones"] if bone["name"] == PARENT_NAME)
    child = next(bone for bone in after["bones"] if bone["name"] == CHILD_NAME)
    if child["parent"] is not None or child["head"] != before_child["head"]:
        raise RuntimeError(f"armature.align changed unexpected parent/head state: {before} -> {after}")
    axis = [parent["tail"][index] - parent["head"][index] for index in range(3)]
    aligned_axis = [child["tail"][index] - child["head"][index] for index in range(3)]
    cross = [axis[1] * aligned_axis[2] - axis[2] * aligned_axis[1], axis[2] * aligned_axis[0] - axis[0] * aligned_axis[2], axis[0] * aligned_axis[1] - axis[1] * aligned_axis[0]]
    if max(abs(value) for value in cross) > 1e-5:
        raise RuntimeError(f"armature.align did not make child axis parallel: {before} -> {after}")

    descriptor, temporary = tempfile.mkstemp(prefix="m16-armature-align-reopen-", suffix=".blend")
    os.close(descriptor)
    temporary_path = pathlib.Path(temporary)
    try:
        bpy.ops.wm.save_as_mainfile(filepath=str(temporary_path), check_existing=False, compress=True)
        bpy.ops.wm.open_mainfile(filepath=str(temporary_path), load_ui=False)
        reopened = state_report()
        if reopened != after:
            raise RuntimeError(f"armature.align save/reopen drift: {after} != {reopened}")
        shutil.copyfile(temporary_path, fixture)
        report = {
            "schemaVersion": 1,
            "task": "M16-GAP-00215",
            "operation": "ARMATURE_ALIGN_DESKTOP",
            "fixture": str(fixture),
            "fixtureSha256": hashlib.sha256(fixture.read_bytes()).hexdigest(),
            "before": before,
            "after": reopened,
            "alreadyAligned": already_aligned,
            "poll": poll,
            "operatorStatus": "FINISHED",
            "mainMutation": "CHILD_ALIGNED_TO_PARENT",
            "saveReopen": "EXACT",
            "blenderVersion": bpy.app.version_string,
        }
        output.parent.mkdir(parents=True, exist_ok=True)
        output.write_text(json.dumps(report, indent=2, sort_keys=True) + "\n", encoding="utf-8")
        print("armature-align-desktop-ok poll=true status=FINISHED mainMutation=child_aligned_to_parent saveReopen=exact")
    finally:
        temporary_path.unlink(missing_ok=True)


if __name__ == "__main__":
    try:
        main()
    except Exception as error:
        print(f"armature-align-desktop-failed: {error}")
        raise SystemExit(1)