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#!/usr/bin/env python3
"""Gehirnamputation Qwen2.5-7B-Instruct: Tokens mit Doppelzeichen entfernen.

Tokenizer (JSON-Roundtrip, tokenizers 0.22.2) + Tensor-Chirurgie (embed/lm_head).
keep_ids = Filter (auf dekodiertem Text) + WHITELIST (added_tokens + special ids).
"""
import os
import json
import shutil
from collections import Counter
from pathlib import Path

os.environ.setdefault("HF_HOME", "/home/david/Schreibtisch/Platte/cache/huggingface")
os.environ.setdefault("HF_HUB_CACHE", "/home/david/Schreibtisch/Platte/cache/huggingface/hub")

import torch
from tokenizers import Tokenizer
from transformers import AutoTokenizer, AutoModelForCausalLM

MODEL_NAME = "unsloth/Qwen2.5-7B-Instruct"
TARGET_DIR = Path("/mnt/models/graf_zahl/qwen_amputated_base")
EXPECTED_KEEP = 106915


def hat_doppelzeichen(text: str) -> bool:
    counts = Counter(c.lower() for c in text if c.isalnum())
    return any(n > 1 for n in counts.values())


def map_id(value, old_to_new):
    if value is None:
        return None
    if isinstance(value, (list, tuple)):
        return [old_to_new[v] for v in value]
    return old_to_new[value]


def main():
    print("=== [1/7] keep_ids bestimmen (Filter + Whitelist) ===", flush=True)
    tok = AutoTokenizer.from_pretrained(MODEL_NAME, trust_remote_code=True)
    vocab_size = len(tok)
    d = json.loads(tok._tokenizer.to_str())
    base_vocab = d["model"]["vocab"]
    merges = d["model"]["merges"]
    added_tokens = d["added_tokens"]
    added_ids = {t["id"] for t in added_tokens}
    special_ids = set(tok.all_special_ids)

    decoded = {}
    CHUNK = 20000
    for i in range(0, vocab_size, CHUNK):
        chunk = list(range(i, min(i + CHUNK, vocab_size)))
        for tid, txt in zip(chunk, tok.batch_decode([[t] for t in chunk], skip_special_tokens=False)):
            decoded[tid] = txt

    keep_ids = [
        oid for oid in range(vocab_size)
        if (oid in added_ids) or (oid in special_ids) or not hat_doppelzeichen(decoded[oid])
    ]
    n_keep = len(keep_ids)
    print(f"  Vokabular {vocab_size} -> {n_keep} (Verlust {(vocab_size - n_keep) / vocab_size * 100:.2f}%)")
    assert n_keep == EXPECTED_KEEP, f"ERWARTET {EXPECTED_KEEP}, IST {n_keep}"

    print("=== [2/7] Mapping old_to_new_id ===", flush=True)
    old_to_new = {old: new for new, old in enumerate(keep_ids)}
    keep_set = set(keep_ids)
    assert all(old_to_new[k] == i for i, k in enumerate(keep_ids))

    print("=== [3/7] Tokenizer-JSON umbauen ===", flush=True)
    new_vocab = {raw: old_to_new[oid] for raw, oid in base_vocab.items() if oid in keep_set}
    new_added = []
    for t in added_tokens:
        nt = dict(t)
        nt["id"] = old_to_new[t["id"]]
        new_added.append(nt)
    new_merges = [
        (a, b) for a, b in merges
        if (a + b) in new_vocab and a in new_vocab and b in new_vocab
    ]
    n_merge_result_only = sum(1 for a, b in merges if (a + b) in new_vocab)
    print(f"  Basis-Vokabular: {len(base_vocab)} -> {len(new_vocab)}")
    print(f"  Added Tokens:    {len(added_tokens)} -> {len(new_added)}")
    print(f"  Merges:          {len(merges)} -> {len(new_merges)} "
          f"(nur Ergebnis-Regel haette {n_merge_result_only} behalten)")

    d["model"]["vocab"] = new_vocab
    d["model"]["merges"] = new_merges
    d["added_tokens"] = new_added
    new_raw = Tokenizer.from_str(json.dumps(d))
    assert new_raw.get_vocab_size() == n_keep, f"{new_raw.get_vocab_size()} != {n_keep}"

    print("=== [4/7] Tokenizer + Config-IDs speichern ===", flush=True)
    TARGET_DIR.mkdir(parents=True, exist_ok=True)
    tok.save_pretrained(TARGET_DIR)
    new_raw.save(str(TARGET_DIR / "tokenizer.json"))

    tc_path = TARGET_DIR / "tokenizer_config.json"
    tc = json.loads(tc_path.read_text(encoding="utf-8"))
    if "added_tokens_decoder" in tc:
        tc["added_tokens_decoder"] = {
            str(old_to_new[int(k)]): v for k, v in tc["added_tokens_decoder"].items()
        }
        tc_path.write_text(json.dumps(tc, ensure_ascii=False, indent=2), encoding="utf-8")
        print(f"  tokenizer_config.json: added_tokens_decoder auf neue IDs gemappt")

    print("=== [5/7] Modell laden (CPU, bf16) ===", flush=True)
    model = AutoModelForCausalLM.from_pretrained(
        MODEL_NAME, device_map="cpu", dtype=torch.bfloat16, trust_remote_code=True,
    )
    print(f"  embed_tokens {tuple(model.model.embed_tokens.weight.shape)}, "
          f"lm_head {tuple(model.lm_head.weight.shape)}, "
          f"tie_word_embeddings={model.config.tie_word_embeddings}")
    assert not model.config.tie_word_embeddings, "Tied embeddings: Slicing muesste anders laufen"

    print("=== [6/7] Tensor-Chirurgie + Config ===", flush=True)
    keep_tensor = torch.tensor(keep_ids, dtype=torch.long)
    with torch.no_grad():
        model.model.embed_tokens.weight.data = model.model.embed_tokens.weight.data[keep_tensor].contiguous()
        model.lm_head.weight.data = model.lm_head.weight.data[keep_tensor].contiguous()
    model.model.embed_tokens.num_embeddings = n_keep
    model.lm_head.out_features = n_keep
    model.config.vocab_size = n_keep

    for name in ("eos_token_id", "bos_token_id", "pad_token_id"):
        for cfg in (model.config, model.generation_config):
            old = getattr(cfg, name, None)
            if old is not None:
                new = map_id(old, old_to_new)
                setattr(cfg, name, new)
                print(f"  {type(cfg).__name__}.{name}: {old} -> {new}")

    assert model.model.embed_tokens.weight.shape[0] == n_keep
    assert model.lm_head.weight.shape[0] == n_keep

    print("=== [7/7] Modell speichern ===", flush=True)
    model.save_pretrained(TARGET_DIR, safe_serialization=True)
    print(f"  Gespeichert in {TARGET_DIR}")

    print("\n=== VERIFIKATION (frisch von Platte) ===", flush=True)
    new_tok = AutoTokenizer.from_pretrained(TARGET_DIR, trust_remote_code=True)
    assert len(new_tok) == n_keep, f"len(new_tok)={len(new_tok)} != {n_keep}"
    for old_id, name in ((151643, "<|endoftext|>"), (151644, "<|im_start|>"), (151645, "<|im_end|>")):
        new_id = old_to_new[old_id]
        got = new_tok.convert_ids_to_tokens(new_id)
        assert got == name, f"{name}: neue ID {new_id} liefert {got!r}"
        print(f"  {name}: {old_id} -> {new_id} OK")

    for s in ["Hallo Welt", "Zaehl bitte: YYYYYYYYYY. Wie viele Y sind das?", "Ah ah ah! 1 2 3 4 5"]:
        ids = new_tok.encode(s, add_special_tokens=False)
        assert max(ids) < n_keep
        back = new_tok.decode(ids)
        print(f"  {s!r} -> {len(ids)} Tokens -> {back!r}  {'OK' if back == s else 'ABWEICHUNG'}")
        assert back == s

    msgs = [{"role": "user", "content": "Hi"}]
    chat_text = new_tok.apply_chat_template(msgs, add_generation_prompt=True, tokenize=False)
    chat_ids = new_tok.encode(chat_text, add_special_tokens=False)
    assert max(chat_ids) < n_keep
    print(f"  Chat-Template: {len(chat_ids)} Tokens, max ID {max(chat_ids)} < {n_keep}")

    check = AutoModelForCausalLM.from_pretrained(TARGET_DIR, device_map="cpu", dtype=torch.bfloat16)
    assert check.model.embed_tokens.weight.shape[0] == n_keep
    assert check.lm_head.weight.shape[0] == n_keep
    assert check.config.vocab_size == n_keep
    ref = model.model.embed_tokens.weight[:5]
    assert torch.equal(check.model.embed_tokens.weight[:5], ref)
    print(f"  Modell neu geladen: embed/lm_head {n_keep} x {check.config.hidden_size}, Gewichte identisch")

    print("\nERFOLG: amputiertes Modell liegt unter", TARGET_DIR)


if __name__ == "__main__":
    main()