import asyncio
import copy
import json
import os
import sys

from typing import List, Dict, Any, Optional

from src import ai_client
from src import models
from src import mcp_client

from src.file_cache import ASTParser


_SENTENCE_TRANSFORMERS = None
_GOOGLE_GENAI          = None
_CHROMADB              = None
LOCAL_RAG_INSTALL_HINT = "Local RAG embeddings require sentence-transformers. Install with manual_slop[local-rag] to use local embeddings."


def _get_sentence_transformers():
 global _SENTENCE_TRANSFORMERS
 if _SENTENCE_TRANSFORMERS is None:
  try:
   from sentence_transformers import SentenceTransformer
   _SENTENCE_TRANSFORMERS = SentenceTransformer
  except ModuleNotFoundError as e:
   if e.name == "sentence_transformers":
    raise ImportError(LOCAL_RAG_INSTALL_HINT) from e
   raise
  except Exception as e:
   sys.stderr.write(f"FAILED to import sentence_transformers: {e}\n")
   sys.stderr.flush()
   raise e
 return _SENTENCE_TRANSFORMERS

def _get_google_genai():
 global _GOOGLE_GENAI
 if _GOOGLE_GENAI is None:
  from google import genai
  from google.genai import types
  _GOOGLE_GENAI = (genai, types)
 return _GOOGLE_GENAI

def _get_chromadb():
 global _CHROMADB
 if _CHROMADB is None:
  import chromadb
  from chromadb.config import Settings
  _CHROMADB = (chromadb, Settings)
 return _CHROMADB

class BaseEmbeddingProvider:
 def embed(self, texts: List[str]) -> List[List[float]]:
  raise NotImplementedError()

class LocalEmbeddingProvider(BaseEmbeddingProvider):
 def __init__(self, model_name: str = 'all-MiniLM-L6-v2'):
  ST = _get_sentence_transformers()
  self.model = ST(model_name)

 def embed(self, texts: List[str]) -> List[List[float]]:
  embeddings = self.model.encode(texts)
  return embeddings.tolist()

class GeminiEmbeddingProvider(BaseEmbeddingProvider):
 def __init__(self, model_name: str = 'gemini-embedding-001'):
  self.model_name = model_name

 def embed(self, texts: List[str]) -> List[List[float]]:
  google_module = _get_google_genai()
  if google_module is None:
   raise ImportError("google-genai is not installed")
  genai_pkg, types = google_module
  ai_client._ensure_gemini_client()
  client = ai_client._gemini_client
  if not client:
   raise ValueError("Gemini client not initialized")
  res = client.models.embed_content(
   model    = self.model_name,
   contents = texts,
   config   = types.EmbedContentConfig(task_type="RETRIEVAL_DOCUMENT")
  )
  return [e.values for e in res.embeddings]

class RAGEngine:
 def __init__(self, config: models.RAGConfig, base_dir: str = "."):
  self.config             = copy.deepcopy(config)
  self.base_dir           = base_dir
  self.client             = None
  self.collection         = None
  self.embedding_provider = None

  if not self.config.enabled: return

  self._init_embedding_provider()
  self._init_vector_store()

 def _init_embedding_provider(self):
  if self.config.embedding_provider == 'gemini':
   self.embedding_provider = GeminiEmbeddingProvider()
  elif self.config.embedding_provider == 'local':
   self.embedding_provider = LocalEmbeddingProvider()
  else:
   raise ValueError(f"Unknown embedding provider: {self.config.embedding_provider}")

 def _init_vector_store(self):
  vs_config = self.config.vector_store
  if vs_config.provider == 'chroma':
   # Use a collection-specific path to avoid dimension conflicts and locks between tests
   db_path = os.path.abspath(os.path.join(self.base_dir, ".slop_cache", f"chroma_{vs_config.collection_name}"))
   os.makedirs(db_path, exist_ok=True)
   chroma_module = _get_chromadb()
   if chroma_module is None:
    raise ImportError("chromadb is not installed")
   chromadb, Settings = chroma_module
   self.client     = chromadb.PersistentClient(path=db_path)
   self.collection = self.client.get_or_create_collection(name=vs_config.collection_name)
   self._validate_collection_dim()
  elif vs_config.provider == 'mock':
   self.client     = "mock"
   self.collection = "mock"
  else:
   raise ValueError(f"Unknown vector store provider: {vs_config.provider}")

 def _validate_collection_dim(self) -> None:
  """
  Detect dimension mismatch between an existing collection's vectors and
  the current embedding provider's output. When mismatched (e.g. the user
  switched from Gemini 3072-dim to local 384-dim, or vice versa), the
  collection is deleted and recreated empty so the next index pass
  populates it with the correct dim. Prevents silent corruption that
  would later surface as a search error ("Collection expecting
  embedding with dimension of X, got Y") and hang live_gui tests.
  [C: tests/test_rag_engine.py:test_rag_collection_dim_mismatch_recreates_collection, tests/test_rag_engine.py:test_rag_collection_dim_match_preserves_collection]
  """
  if self.collection is None or self.collection == "mock" or self.embedding_provider is None:
   return
  try:
   res = self.collection.get(limit=1, include=["embeddings"])
   if not res:
    return
   embeddings = res.get("embeddings") if isinstance(res, dict) else None
   if not embeddings or len(embeddings) == 0:
    return
   existing_dim = len(embeddings[0])
   expected_dim = len(self.embedding_provider.embed(["__rag_dim_check__"])[0])
   if existing_dim == expected_dim:
    return
   sys.stderr.write(
    f"RAG: Collection '{self.collection.name}' dim mismatch "
    f"(existing={existing_dim}, expected={expected_dim}). "
    f"Recreating collection to prevent silent corruption.\n"
   )
   sys.stderr.flush()
   self.client.delete_collection(self.collection.name)
   self.collection = self.client.get_or_create_collection(name=self.collection.name)
  except Exception as e:
   sys.stderr.write(f"RAG: Failed to validate collection dim: {e}\n")
   sys.stderr.flush()

 def is_empty(self) -> bool:
  if not self.config.enabled:
   return True
  if self.config.vector_store.provider == 'mock' or self.collection == "mock":
   return True
  if self.collection is None:
   return True
  return self.collection.count() == 0

 def add_documents(self, ids: List[str], texts: List[str], metadatas: Optional[List[Dict[str, Any]]] = None):
  """
  [C: tests/test_rag_engine.py:test_rag_engine_chroma]
  """
  if not self.config.enabled or self.collection == "mock":
   return
  embeddings = self.embedding_provider.embed(texts)
  self.collection.upsert(
   ids        = ids,
   embeddings = embeddings,
   documents  = texts,
   metadatas  = metadatas
  )

 def _chunk_text(self, content: str) -> List[str]:
  """Character-based chunking with overlap."""
  chunks = []
  if not content:
   return chunks
  chunk_size = self.config.chunk_size
  overlap    = self.config.chunk_overlap
  start      = 0
  while start < len(content):
   end = start + chunk_size
   chunks.append(content[start:end])
   if end >= len(content):
    break
   start += (chunk_size - overlap)
  return chunks

 def _chunk_code(self, content: str, file_path: str) -> List[str]:
  """AST-aware chunking for Python code."""
  try:
   parser = ASTParser("python")
   tree   = parser.parse(content)
   chunks = []

   for node in tree.root_node.children:
    if node.type in ("function_definition", "class_definition"):
     chunks.append(content[node.start_byte:node.end_byte])

   if not chunks or len(content) < self.config.chunk_size:
    return self._chunk_text(content)
   return chunks
  except Exception:
   return self._chunk_text(content)

 def index_file(self, file_path: str):
  """Reads, chunks, and indexes a file into the vector store."""
  if not self.config.enabled or self.collection == "mock":
   return

  full_path = os.path.join(self.base_dir, file_path)
  if not os.path.exists(full_path):
   # CWD fallback: handle the case where base_dir was resolved to a
   # parent directory (e.g. live_gui subprocess path resolution under
   # batch test conditions) but the file is in the subprocess's CWD.
   # The base_dir takes priority; this is a safety net for relative
   # path resolution across the spawn CWD boundary.
   cwd_path = os.path.join(os.getcwd(), file_path)
   if os.path.exists(cwd_path):
    full_path = cwd_path
   else:
    return

  try:
   mtime = os.path.getmtime(full_path)
  except Exception:
   return

  try:
   res = self.collection.get(where={"path": file_path}, limit=1, include=["metadatas"])
   if res and res["metadatas"] and res["metadatas"][0]:
    if res["metadatas"][0].get("mtime") == mtime:
     return
  except Exception:
   pass

  try:
   with open(full_path, "r", encoding="utf-8", errors="ignore") as f:
    content = f.read()
  except Exception:
   return

  self.collection.delete(where={"path": file_path})

  if file_path.lower().endswith(".py"):
   chunks = self._chunk_code(content, file_path)
  else:
   chunks = self._chunk_text(content)

  if not chunks:
   return

  ids       = [f"{file_path}_{i}" for i in range(len(chunks))]
  metadatas = [{"path": file_path, "chunk": i, "mtime": mtime} for i in range(len(chunks))]
  self.add_documents(ids, chunks, metadatas)

 def _search_mcp(self, query: str, top_k: int = 5) -> List[Dict[str, Any]]:
  async def _async_search_mcp():
   tool_name = self.config.vector_store.mcp_tool or "rag_search"
   args      = {"query": query, "top_k": top_k}
   res_str   = await mcp_client.async_dispatch(tool_name, args)
   try:
    data = json.loads(res_str)
    if isinstance(data, list):
     return data
    elif isinstance(data, dict) and "results" in data:
     return data["results"]
    return []
   except:
    return []

  return asyncio.run(_async_search_mcp())

 def search(self, query: str, top_k: int = 5) -> List[Dict[str, Any]]:
  """
  [C: tests/mock_concurrent_mma.py:main, tests/test_rag_engine.py:test_rag_engine_chroma]
  """
  if not self.config.enabled:                     return []
  if self.config.vector_store.provider == 'mcp':  return self._search_mcp(query, top_k)
  if self.collection                   == "mock": return []

  query_embedding = self.embedding_provider.embed([query])[0]
  results         = self.collection.query(
   query_embeddings = [query_embedding],
   n_results        = top_k
  )

  ret = []
  if results and results["ids"] and results["ids"][0]:
   for i in range(len(results["ids"][0])):
    ret.append({
     "id":       results["ids"][0][i],
     "document": results["documents"][0][i],
     "metadata": results["metadatas"][0][i] if results["metadatas"] else {},
     "distance": results["distances"][0][i] if "distances" in results and results["distances"] else 0.0
    })
  return ret

 def delete_documents(self, ids: List[str]):
  """
  [C: tests/test_rag_engine.py:test_rag_engine_chroma]
  """
  if not self.config.enabled or self.collection == "mock":
   return
  self.collection.delete(ids=ids)

 def get_all_indexed_paths(self) -> List[str]:
  if not self.config.enabled or self.collection == "mock":
   return []
  res = self.collection.get(include=["metadatas"])
  if not res or not res["metadatas"]:
   return []
  return list(set(m.get("path") for m in res["metadatas"] if m.get("path")))

 def delete_documents_by_path(self, file_paths: List[str]):
  if not self.config.enabled or self.collection == "mock":
   return
  for path in file_paths:
   self.collection.delete(where={"path": path})