from pathlib import Path
import shutil
import re

path = Path("models/minimax_h3/pipeline.py")
backup = Path("models/minimax_h3/pipeline.py.sagefix_backup")

PATCH_MARKER = "# SAGEFIX: Qwen3-VL must use SDPA"

if not path.exists():
    raise FileNotFoundError(
        f"Couldn't find:\n  {path.resolve()}\n\n"
        "Run this script from the Wan2GP root directory."
    )

text = path.read_text(encoding="utf-8")

# ------------------------------------------------------------
# Already patched?
# ------------------------------------------------------------

if PATCH_MARKER in text:
    print("✅ MiniMax H3 Sage/Qwen fix is already installed.")
    raise SystemExit(0)


# ------------------------------------------------------------
# Locate _encode_prompt() structurally
# ------------------------------------------------------------

start = text.find("    def _encode_prompt(self, prompt, presentation):")

if start == -1:
    raise RuntimeError(
        "❌ Could not locate _encode_prompt() in pipeline.py.\n"
        "Nothing was modified."
    )

# Find the next method in the class
end_match = re.search(r"\n    def \w+\(", text[start + 5:])

if end_match:
    end = start + 5 + end_match.start()
else:
    end = len(text)

old_function = text[start:end]

print("Found current _encode_prompt():")
print("------------------------------------------------------------")
print(old_function)
print("------------------------------------------------------------")


# ------------------------------------------------------------
# Sanity checks
# ------------------------------------------------------------

required_bits = [
    "if self.fixed_prompt is not None:",
    "def encode_fn(prompts):",
    "self.text_encoder.encode(",
    "self.text_encoder_cache.encode(",
]

missing = [x for x in required_bits if x not in old_function]

if missing:
    print("❌ The function structure has changed unexpectedly.")
    print("Missing expected pieces:")
    for item in missing:
        print(f"  - {item}")

    raise RuntimeError(
        "SageFix aborted safely. Nothing was modified."
    )


# ------------------------------------------------------------
# Build replacement function
# ------------------------------------------------------------

new_function = '''    def _encode_prompt(self, prompt, presentation):
        if self.fixed_prompt is not None:
            return self.fixed_prompt.prompt_embeds.to(device=self.device, dtype=self.dtype), self.fixed_prompt.text_token_tags

        # SAGEFIX: Qwen3-VL must use SDPA
        #
        # Qwen3-VL's variable-length attention can use head dimensions
        # unsupported by SageAttention v1. Temporarily switch to SDPA
        # during prompt/reference encoding, then restore the selected
        # backend for MiniMax H3 denoising.
        previous_attention = offload.shared_state.get("_attention", "sdpa")
        offload.shared_state["_attention"] = "sdpa"

        try:
            def encode_fn(prompts):
                return [self.text_encoder.encode(prompts[0], presentation, self.device, self.dtype)]

            cache_key = self._prompt_cache_key(prompt, presentation)
            return self.text_encoder_cache.encode(
                encode_fn,
                prompt,
                device=self.device,
                cache_keys=cache_key
            )[0]

        finally:
            offload.shared_state["_attention"] = previous_attention
'''


# ------------------------------------------------------------
# Backup CURRENT unpatched version
# ------------------------------------------------------------

shutil.copy2(path, backup)
print(f"✅ Backup created/refreshed:\n   {backup}")


# ------------------------------------------------------------
# Apply replacement
# ------------------------------------------------------------

patched_text = text[:start] + new_function + text[end:]

path.write_text(patched_text, encoding="utf-8")

print("✅ Sage/Qwen compatibility patch applied.")


# ------------------------------------------------------------
# Syntax verification
# ------------------------------------------------------------

try:
    compile(
        path.read_text(encoding="utf-8"),
        str(path),
        "exec"
    )
except Exception:
    print("❌ Syntax check failed. Restoring backup...")
    shutil.copy2(backup, path)
    print("✅ Original pipeline.py restored.")
    raise

print("✅ Python syntax check passed.")


# ------------------------------------------------------------
# Show result
# ------------------------------------------------------------

patched = path.read_text(encoding="utf-8")
start2 = patched.find("    def _encode_prompt(self, prompt, presentation):")
end_match2 = re.search(r"\n    def \w+\(", patched[start2 + 5:])

if end_match2:
    end2 = start2 + 5 + end_match2.start()
else:
    end2 = len(patched)

print()
print("--------------- PATCHED FUNCTION ---------------")
print()
print(patched[start2:end2])
print()
print("------------------------------------------------")
print()
print("🚀 SageFix complete.")
print("Qwen3-VL encoding → SDPA")
print("MiniMax H3        → selected backend (e.g. Sage)")