import os
import glob
import json
import argparse
from typing import Dict, List, Tuple

import torch
import torch.nn as nn
import torch.nn.functional as F
from safetensors.torch import load_file
from huggingface_hub import hf_hub_download
from transformers import AutoImageProcessor, AutoModelForCausalLM, AutoTokenizer

# -----------------------------
# Utils
# -----------------------------
def load_jsonl(path: str) -> List[dict]:
    data = []
    with open(path, "r") as f:
        for line in f:
            line = line.strip()
            if not line:
                continue
            data.append(json.loads(line))
    return data


def load_safetensor_from_hf(repo_id, filename, repo_type="dataset"):
    cached_path = hf_hub_download(
        repo_id=repo_id,
        filename=filename,
        repo_type=repo_type,
        local_files_only=False
    )
    return load_file(cached_path)


def to_vchw(point_map: torch.Tensor) -> torch.Tensor:
    """
    Convert point_map to (V, 3, H, W) float tensor.
    Accepts common layouts:
      (V, 3, H, W)  -> ok
      (V, H, W, 3)  -> permute
      (V, H, W, C) where C=3 -> permute
    """
    if point_map.dim() != 4:
        raise ValueError(f"Expected point_map to be 4D (V,*,*,*), got shape={tuple(point_map.shape)}")

    V, a, b, c = point_map.shape

    # (V, 3, H, W)
    if a == 3:
        out = point_map
    # (V, H, W, 3)
    elif c == 3:
        out = point_map.permute(0, 3, 1, 2).contiguous()
    else:
        raise ValueError(f"Unrecognized point_map layout: shape={tuple(point_map.shape)}")

    return out.float()


def load_pretrain(model, pretrain_ckpt_path):
    print(f"📂 Loading pretrained weights from: {str(pretrain_ckpt_path)}")
    
    # Search for safetensors files
    model_weight_path_pattern = pretrain_ckpt_path + "/model*.safetensors"
    model_weight_paths = glob.glob(model_weight_path_pattern)

    if len(model_weight_paths) == 0:
        raise FileNotFoundError(f"❌ Cannot find any .safetensors file in {str(pretrain_ckpt_path)}")

    # Load and merge weights
    weights = {}
    for model_weight_path in model_weight_paths:
        print(f"📥 Loading weights from: {model_weight_path}")
        weights.update(load_file(model_weight_path, device="cpu"))

    # Load weights with strict=False
    result = model.load_state_dict(weights, strict=False)
    
    model_keys = set(model.state_dict().keys())
    loaded_keys = model_keys.intersection(weights.keys())
    missing_keys = result.missing_keys
    unexpected_keys = result.unexpected_keys
    print(f"✅ Loaded keys:      {len(loaded_keys)} / {len(model_keys)}")
    print(f"❌ Missing keys:     {len(missing_keys)}")
    print(f"⚠️ Unexpected keys:  {len(unexpected_keys)}")

class _GlobalViewAttnBlock(nn.Module):
    """One pre-norm Transformer-style block over view tokens (B,V,D)."""
    def __init__(
        self,
        dim: int,
        num_heads: int,
        mlp_ratio: float,
        dropout: float,
        zero_init_residual: bool,
        zero_init_attn_out: bool,
    ):
        super().__init__()
        self.zero_init_residual = zero_init_residual
        self.zero_init_attn_out = zero_init_attn_out

        self.norm1 = nn.LayerNorm(dim)
        self.attn = nn.MultiheadAttention(
            embed_dim=dim,
            num_heads=num_heads,
            dropout=dropout,
            batch_first=True,
            bias=True,
        )

        self.norm2 = nn.LayerNorm(dim)
        hidden_dim = int(dim * mlp_ratio)
        self.mlp = nn.Sequential(
            nn.Linear(dim, hidden_dim),
            nn.GELU(),
            nn.Dropout(dropout),
            nn.Linear(hidden_dim, dim),
            nn.Dropout(dropout),
        )

        self._init_weights()

    def forward(self, x, key_padding_mask=None):
        h = self.norm1(x)
        attn_out, _ = self.attn(
            h, h, h,
            key_padding_mask=key_padding_mask,
            need_weights=False,
        )
        x = x + attn_out
        x = x + self.mlp(self.norm2(x))
        return x

    @torch.no_grad()
    def _init_weights(self):
        # LayerNorm
        for ln in (self.norm1, self.norm2):
            nn.init.ones_(ln.weight)
            nn.init.zeros_(ln.bias)

        # MultiheadAttention: in_proj for qkv (3D, D)
        if getattr(self.attn, "in_proj_weight", None) is not None:
            nn.init.xavier_uniform_(self.attn.in_proj_weight)
        if getattr(self.attn, "in_proj_bias", None) is not None:
            nn.init.zeros_(self.attn.in_proj_bias)

        # out proj
        nn.init.xavier_uniform_(self.attn.out_proj.weight)
        if self.attn.out_proj.bias is not None:
            nn.init.zeros_(self.attn.out_proj.bias)

        # optional: start attn residual near-zero
        if self.zero_init_attn_out:
            nn.init.zeros_(self.attn.out_proj.weight)
            if self.attn.out_proj.bias is not None:
                nn.init.zeros_(self.attn.out_proj.bias)

        # MLP
        fc1: nn.Linear = self.mlp[0]
        fc2: nn.Linear = self.mlp[3]

        nn.init.xavier_uniform_(fc1.weight)
        if fc1.bias is not None:
            nn.init.zeros_(fc1.bias)

        # zero-init last projection for stable residual start (recommended)
        if self.zero_init_residual:
            nn.init.zeros_(fc2.weight)
            if fc2.bias is not None:
                nn.init.zeros_(fc2.bias)
        else:
            nn.init.xavier_uniform_(fc2.weight)
            if fc2.bias is not None:
                nn.init.zeros_(fc2.bias)

class _GlobalViewGatedAttnBlock(nn.Module):
    """Pre-norm Transformer block over view tokens (B,V,D) with gated residuals."""
    def __init__(
        self,
        dim: int,
        num_heads: int,
        mlp_ratio: float,
        dropout: float,
        zero_init_residual: bool,
        zero_init_attn_out: bool,
        gate_bias_init: float = -2.0,   # sigmoid(-2)≈0.12, starts near-identity (small updates)
    ):
        super().__init__()
        self.zero_init_residual = zero_init_residual
        self.zero_init_attn_out = zero_init_attn_out

        self.norm1 = nn.LayerNorm(dim)
        self.attn = nn.MultiheadAttention(
            embed_dim=dim,
            num_heads=num_heads,
            dropout=dropout,
            batch_first=True,
            bias=True,
        )

        # --- Gating for attention residual ---
        # Produces per-token, per-channel gates in (0,1)
        self.attn_gate = nn.Linear(dim, dim, bias=True)

        self.norm2 = nn.LayerNorm(dim)
        hidden_dim = int(dim * mlp_ratio)
        self.mlp = nn.Sequential(
            nn.Linear(dim, hidden_dim),
            nn.GELU(),
            nn.Dropout(dropout),
            nn.Linear(hidden_dim, dim),
            nn.Dropout(dropout),
        )

        # --- Gating for MLP residual ---
        self.mlp_gate = nn.Linear(dim, dim, bias=True)

        self._init_weights(gate_bias_init=gate_bias_init)

    def forward(self, x: torch.Tensor, key_padding_mask=None) -> torch.Tensor:
        # x: (B, V, D)
        h1 = self.norm1(x)
        attn_out, _ = self.attn(
            h1, h1, h1,
            key_padding_mask=key_padding_mask,
            need_weights=False,
        )
        g_attn = torch.sigmoid(self.attn_gate(h1))          # (B, V, D)
        x = x + g_attn * attn_out

        h2 = self.norm2(x)
        mlp_out = self.mlp(h2)
        g_mlp = torch.sigmoid(self.mlp_gate(h2))            # (B, V, D)
        x = x + g_mlp * mlp_out
        return x

    @torch.no_grad()
    def _init_weights(self, gate_bias_init: float):
        # LayerNorm
        for ln in (self.norm1, self.norm2):
            nn.init.ones_(ln.weight)
            nn.init.zeros_(ln.bias)

        # MultiheadAttention: in_proj for qkv
        if getattr(self.attn, "in_proj_weight", None) is not None:
            nn.init.xavier_uniform_(self.attn.in_proj_weight)
        if getattr(self.attn, "in_proj_bias", None) is not None:
            nn.init.zeros_(self.attn.in_proj_bias)

        # out proj
        nn.init.xavier_uniform_(self.attn.out_proj.weight)
        if self.attn.out_proj.bias is not None:
            nn.init.zeros_(self.attn.out_proj.bias)

        # optional: start attn residual near-zero
        if self.zero_init_attn_out:
            nn.init.zeros_(self.attn.out_proj.weight)
            if self.attn.out_proj.bias is not None:
                nn.init.zeros_(self.attn.out_proj.bias)

        # MLP
        fc1: nn.Linear = self.mlp[0]
        fc2: nn.Linear = self.mlp[3]
        nn.init.xavier_uniform_(fc1.weight)
        if fc1.bias is not None:
            nn.init.zeros_(fc1.bias)

        if self.zero_init_residual:
            nn.init.zeros_(fc2.weight)
            if fc2.bias is not None:
                nn.init.zeros_(fc2.bias)
        else:
            nn.init.xavier_uniform_(fc2.weight)
            if fc2.bias is not None:
                nn.init.zeros_(fc2.bias)

        # Gates: start “mostly closed” so training is stable, then learn to open
        nn.init.zeros_(self.attn_gate.weight)
        nn.init.constant_(self.attn_gate.bias, gate_bias_init)

        nn.init.zeros_(self.mlp_gate.weight)
        nn.init.constant_(self.mlp_gate.bias, gate_bias_init)
                
class GlobalViewAttention(nn.Module):
    """
    Multi-layer global self-attention over multi-view tokens.

    Input:  x ∈ (B, V, D)
    Output: x' ∈ (B, V, D)
    """
    def __init__(
        self,
        dim: int,
        num_layers: int = 1,
        num_heads: int = 8,
        mlp_ratio: float = 4.0,
        dropout: float = 0.0,
        zero_init_residual: bool = True,   # recommended (stable when adding layers)
        zero_init_attn_out: bool = False,  # optional extra safety
    ):
        super().__init__()
        assert num_layers >= 1, "num_layers must be >= 1"

        self.dim = dim
        self.num_layers = num_layers
        self.num_heads = num_heads
        self.layers = nn.ModuleList([
            _GlobalViewAttnBlock(
                dim=dim,
                num_heads=num_heads,
                mlp_ratio=mlp_ratio,
                dropout=dropout,
                zero_init_residual=zero_init_residual,
                zero_init_attn_out=zero_init_attn_out,
            )
            for _ in range(num_layers)
        ])

    def forward(self, x, key_padding_mask=None):
        """
        x: (B, V, D)
        key_padding_mask: (B, V), True = ignore (padding)
        """
        for layer in self.layers:
            x = layer(x, key_padding_mask=key_padding_mask)
        return x
    
class RepModel(nn.Module):
    def __init__(self, model_root: str = "fg-clip-base"):
        super().__init__()

        self.pm_encoder = AutoModelForCausalLM.from_pretrained(f'../{model_root}', trust_remote_code=True)
        # self.global_attn = GlobalViewAttention(dim=512, num_heads=8, mlp_ratio=4.0, dropout=0.1)
        self.tokenizer = AutoTokenizer.from_pretrained(f'../{model_root}', trust_remote_code=True, use_fast=True)
        self.image_processor = AutoImageProcessor.from_pretrained(f'../{model_root}')

        # Optional: print trainable params
        try:
            self.pm_encoder.print_trainable_parameters()
        except Exception:
            pass

    @torch.no_grad()
    def encode_views(self, pm_batched):
        # Expect (1,V,3,H,W) or (V,3,H,W)
        # pm_batched = self.image_processor(images=pm_batched, return_tensors="pt").to('cuda')
        _, feats = self.pm_encoder.get_image_features(pm_batched)
        # feats = self.global_attn(feats)
        feats = torch.nn.functional.normalize(feats.float(), dim=-1)
        return feats
    
    @torch.no_grad()
    def encode_text(self, texts):
        tok = self.tokenizer(texts, padding="max_length", truncation=True, max_length=248, return_tensors="pt").to('cuda')
        feats = self.pm_encoder.get_text_features(tok["input_ids"], walk_short_pos=False)
        feats = torch.nn.functional.normalize(feats.float(), dim=-1)
        return feats


# -----------------------------
# Retrieval evaluation
# -----------------------------
@torch.no_grad()
def eval_view_retrieval(
    model: RepModel,
    items: List[dict],
    scan_root: str,
    device: str = "cuda",
    batch_views: int = 32,
    recall_ks: Tuple[int, ...] = (1, 5, 10),
) -> Dict[str, float]:
    model.eval()
    model.to(device)

    # Cache: scan_id -> (V, D) view features
    scan_cache: Dict[str, torch.Tensor] = {}

    total = 0
    top1_correct = 0
    recall_correct = {k: 0 for k in recall_ks}

    for it in items:
        scan_id = it["scan_id"]
        utter = it["utterance"]
        gt_views = it.get("view_ground_truth", None)
        if not gt_views:
            continue
        gt = int(gt_views[0])  # "the first of the view gt"

        # Load / cache view features for this scan
        if scan_id not in scan_cache:
            filename = f'light_scannet/{scan_id}.safetensors'
            data = load_safetensor_from_hf('MatchLab/ScenePoint', filename, repo_type="dataset")

            # if "point_map" not in data:
            #     raise KeyError(f"{st_path} does not contain key 'point_map'. keys={list(data.keys())}")

            pm = to_vchw(data["point_map"])  # (V, 3, H, W)
            # pm = data['color_images']
            
            V = pm.shape[0]

            feats = model.encode_views(pm.to(device, non_blocking=True))  # (chunk, D)
            scan_cache[scan_id] = feats  # (V, D) on CPU

        view_feats = scan_cache[scan_id]  # (V, D), CPU
        V = view_feats.shape[0]
        if gt < 0 or gt >= V:
            # skip invalid gt index
            continue

        # Encode text
        text_feat = model.encode_text(utter).squeeze(0).unsqueeze(-1)  # (D,)

        # Similarity: (V,)
        sims = (view_feats @ text_feat).squeeze(-1)
    
        # rank views by similarity (high -> low)
        ranked = torch.argsort(sims, descending=True)

        pred = int(ranked[0].item())
        total += 1

        if pred == gt:
            top1_correct += 1
        else:
            # per-sample print (optional)
            print(f"GT: {gt}, Pred: {pred}, Utterance: {utter}")

        # Recall@K
        for k in recall_ks:
            k_eff = min(k, V)
            if (ranked[:k_eff] == gt).any().item():
                recall_correct[k] += 1

    # ----- after the loop -----
    out = {}
    if total == 0:
        return {"n": 0}

    out["n"] = total
    out["top1_acc"] = top1_correct / total
    for k in recall_ks:
        out[f"recall@{k}"] = recall_correct[k] / total

    return out

def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--jsonl", type=str, required=True, help="SR3D-style jsonl file")
    ap.add_argument("--scan_root", type=str, required=True, help="Root dir containing scan safetensors")
    ap.add_argument("--ckpt", type=str, default="", help="Optional: path to .pth/.pt or dir with model*.safetensors")
    ap.add_argument("--model_root", type=str, default="fg-clip-base")
    ap.add_argument("--device", type=str, default="cuda")
    ap.add_argument("--batch_views", type=int, default=32)
    ap.add_argument("--max_items", type=int, default=-1)
    args = ap.parse_args()

    items = load_jsonl(args.jsonl)
    if args.max_items > 0:
        items = items[: args.max_items]

    model = RepModel(model_root=args.model_root)
    if args.ckpt:
        load_pretrain(model, args.ckpt)

    metrics = eval_view_retrieval(
        model=model,
        items=items,
        scan_root=args.scan_root,
        device=args.device,
        batch_views=args.batch_views,
        recall_ks=(1, 5, 10),
    )

    print("\n=== View Retrieval Results ===")
    for k, v in metrics.items():
        if isinstance(v, float):
            print(f"{k:>10}: {v:.4f}")
        else:
            print(f"{k:>10}: {v}")


if __name__ == "__main__":
    main()