"""M3 texel store: parse the game wire's action-0x1a texture uploads into a
handle -> (u_size, v_size, mode, RGB array) dict. Format: header[32] =
{handle, byte_size, u, v, mode, ...}, then v rows of 256 bytes, then n=u*v texels.

TEXEL WORD = [pad, B, G, R] bytes -- "SVT xbgr" (ground truth: dpl3-revive
patha/vrboard.py:448 `do_texels` + stage_assets.py:43, the actual renderer's own
decode). Byte 0 is a PAD (verified: 0 in every texel across the capture); the
colour is bytes 1,2,3 = B,G,R, so RGB = bytes (3,2,1). There is NO alpha byte --
cutout ("dpl_tex_value_cut") is done by NEAR-BLACK keying at draw time, not a
stored channel (patha/vrview_gl.py). `mode` 1 is the board's internal 8-bit
storage path; the WIRE upload is always 4 bytes/texel regardless of mode.

Reading RGB as bytes (0,1,2) = (pad,B,G) -- zero red -- was the all-CYAN bug."""
import struct
import numpy as np


def build_texstore(recs):
    store = {}
    i = 0
    while i < len(recs):
        a, p = recs[i]
        if a == 0x1a and len(p) == 32:
            h = [struct.unpack_from('<I', p, 4 * k)[0] for k in range(8)]
            handle, u, v, mode = h[0], h[2], h[3], h[4]
            rb = b''
            j = i + 1
            while j < len(recs) and recs[j][0] == 0x1a and len(recs[j][1]) == 256:
                rb += bytes(recs[j][1]); j += 1
            n = u * v
            if n and len(rb) >= n * 4:
                arr = np.frombuffer(rb[:n * 4], dtype=np.uint8).reshape(v, u, 4)
                # texel = [pad,B,G,R] -> RGB = bytes (3,2,1); v-flip (rows arrive
                # bottom-up: 'PLAYER' reads mirrored otherwise)
                rgb = arr[::-1, :, 3:0:-1].copy()          # (R,G,B) from (3,2,1)
                store[handle] = (u, v, mode, rgb)
            i = j
        else:
            i += 1
    return store