#!/usr/bin/env python3
"""Exercise the actual windowless ASM renderer through its public mailbox."""
import ctypes as C
import mmap
import os
from pathlib import Path
import struct
import subprocess
import time

ROOT = Path(__file__).resolve().parents[1]
SIZE, TEXTURES, PIXELS = 1357792, 2016, 1050592


def check_preview(engine, expected=None, output=None):
    name = f"Local\\EblanPreview-test-{os.getpid()}-{time.monotonic_ns()}"
    with mmap.mmap(-1, SIZE, tagname=name) as packet:
        base = C.addressof(C.c_char.from_buffer(packet))
        state = C.cast(base+8, C.POINTER(C.c_long))
        struct.pack_into("<4I3i6I", packet, 0, 0x56504245, 1, 0, os.getpid(), 160, 1024, 0,
                         0x383838, 0x222222, 0, 0, 0, 1)
        for y in range(32): packet[128+y*32+10] = 1
        # Flat red wall, other slots black; proves texture upload rather than fallback.
        packet[TEXTURES+65536:TEXTURES+2*65536] = struct.pack("<I",0xE02010)*16384
        proc = subprocess.Popen([str(engine), "--preview:"+name], cwd=ROOT,
                                creationflags=subprocess.CREATE_NO_WINDOW)

        def request():
            # Aligned DWORD stores are atomic and release-ordered on x86/x64.
            # Payload writes above finish before publishing the request.
            state[0]=1
            deadline = time.monotonic()+5
            while state[0] != 2:
                if proc.poll() is not None: raise AssertionError(f"Preview process exited: {proc.returncode}")
                if time.monotonic()>deadline: raise AssertionError("Preview renderer did not answer")
                time.sleep(.005)
            return packet[PIXELS:PIXELS+307200]

        try:
            frame=request()
            middle=struct.unpack_from("<I",frame,(120*320+160)*4)[0]
            assert middle not in (0,0x383838,0x222222), "Wall was not rendered"
            packet[128+16*32+5]=4
            changed=request()
            assert changed!=frame, "Unsaved wall change did not reach the renderer"
            packet[128+16*32+5]=0
            struct.pack_into("<2I",packet,40,1,16)
            assert not any(request()), "Full cinematic fade is not black"
            struct.pack_into("<2I",packet,40,1,0)
            packet[1920:1920+7]="Привет".encode("cp1251")+b"\0"
            subtitle=request()
            assert not any(subtitle[:8*320*4]) and not any(subtitle[188*320*4:]), "Letterbox missing"
            assert subtitle!=frame, "Subtitle overlay missing"
            # Compare the live IPC output with a direct Render3DScene regression dump.
            if expected:
                data=(ROOT/"assets/map.dat").read_bytes()
                h=struct.unpack_from("<I7HII",data)
                version=h[1]; count=h[7]
                struct.pack_into("<3i",packet,16,h[4]*64+32,h[5]*64+32,h[6])
                struct.pack_into("<5I",packet,28,h[8],h[9],count,0,0)
                packet[128:1152]=data[38:1062]
                sprites=bytearray(data[1062:1062+count*24])
                if version==1:
                    for i in range(count):
                        x,y=struct.unpack_from("<ii",sprites,i*24)
                        struct.pack_into("<ii",sprites,i*24,x>>16,y>>16)
                packet[1152:1152+len(sprites)]=sprites
                pack=(ROOT/"assets/textures/texturepack.bin").read_bytes()
                packet[TEXTURES:TEXTURES+len(pack)-8]=pack[8:]
                struct.pack_into("<I",packet,48,2)
                actual=request()
                assert actual==Path(expected).read_bytes(), "Viewport differs from the standalone ASM renderer"
                if output:
                    header=struct.pack("<2sIHHI",b"BM",307254,0,0,54)
                    header+=struct.pack("<IiiHHIIiiII",40,320,-240,1,32,0,307200,0,0,0,0)
                    Path(output).write_bytes(header+actual)
            state[0]=3
            assert proc.wait(timeout=5)==0, "Preview did not exit cleanly"
            print("PASS live ASM viewport: map edits, texture upload, letterbox, subtitles, fade and clean shutdown")
            if expected: print("PASS live viewport pixels exactly match the standalone ASM renderer")
        finally:
            if proc.poll() is None: proc.terminate(); proc.wait(timeout=5)
            del state


if __name__ == "__main__":
    check_preview(ROOT/"engine.exe")