"""

  Configuration loader and validator for search engine configurations.

  
  This module handles loading, parsing, and validating YAML configuration files

  that define how search engine data should be indexed and searched.

  """
  
  import yaml
  import os
  from typing import Dict, Any, List, Optional
  from dataclasses import dataclass, field
  from pathlib import Path
  
  from .field_types import (
      FieldConfig, FieldType, AnalyzerType,
      FIELD_TYPE_MAP, ANALYZER_MAP
  )
  
  
  @dataclass
  class IndexConfig:
      """Configuration for an index domain (e.g., default, title, brand)."""
      name: str
      label: str
      fields: List[str]  # List of field names to include
      analyzer: AnalyzerType
      boost: float = 1.0
      example: Optional[str] = None
  

      # Multi-language field mapping: {"zh": ["name"], "en": ["enSpuName"], "ru": ["ruSkuName"]}
      language_field_mapping: Optional[Dict[str, List[str]]] = None
  

  
  @dataclass
  class RankingConfig:
      """Configuration for ranking expressions."""
      expression: str  # e.g., "bm25() + 0.2*text_embedding_relevance()"
      description: str
  
  
  @dataclass
  class QueryConfig:
      """Configuration for query processing."""
      supported_languages: List[str] = field(default_factory=lambda: ["zh", "en"])
      default_language: str = "zh"
      enable_translation: bool = True
      enable_text_embedding: bool = True
      enable_query_rewrite: bool = True
      rewrite_dictionary: Dict[str, str] = field(default_factory=dict)
  
      # Translation API settings
      translation_api_key: Optional[str] = None
      translation_service: str = "deepl"  # deepl, google, etc.

      translation_glossary_id: Optional[str] = None  # DeepL glossary ID for custom terminology
      translation_context: str = "e-commerce product search"  # Context hint for translation

      # Embedding field names - if not set, will auto-detect from fields

      text_embedding_field: Optional[str] = None  # Field name for text embeddings (e.g., "title_embedding")

      image_embedding_field: Optional[str] = None  # Field name for image embeddings (e.g., "image_embedding")
  

      # Embedding disable thresholds (disable vector search for short queries)
      embedding_disable_chinese_char_limit: int = 4  # Disable embedding for Chinese queries with <= this many characters
      embedding_disable_english_word_limit: int = 3  # Disable embedding for English queries with <= this many words
  

      # ES source fields configuration - fields to return in search results

      # If None, auto-collect from field configs (fields with return_in_source=True)
      # If empty list, return all fields. Otherwise, only return specified fields.
      source_fields: Optional[List[str]] = None

  
  @dataclass
  class SPUConfig:
      """Configuration for SPU aggregation."""
      enabled: bool = False
      spu_field: Optional[str] = None  # Field containing SPU ID
      inner_hits_size: int = 3
  
  
  @dataclass

  class FunctionScoreConfig:
      """Function Score配置（ES层打分规则）"""
      score_mode: str = "sum"  # multiply, sum, avg, first, max, min
      boost_mode: str = "multiply"  # multiply, replace, sum, avg, max, min
      functions: List[Dict[str, Any]] = field(default_factory=list)
  
  
  @dataclass
  class RerankConfig:
      """本地重排配置（当前禁用）"""
      enabled: bool = False
      expression: str = ""
      description: str = ""
  
  
  @dataclass

  class SearchConfig:

      """Complete configuration for search engine (multi-tenant)."""

      # Field definitions
      fields: List[FieldConfig]
  
      # Index structure (query domains)
      indexes: List[IndexConfig]
  
      # Query processing
      query_config: QueryConfig
  
      # Ranking configuration
      ranking: RankingConfig
  

      # Function Score configuration (ES层打分)
      function_score: FunctionScoreConfig
  
      # Rerank configuration (本地重排)
      rerank: RerankConfig
  

      # SPU configuration
      spu_config: SPUConfig
  
      # ES index settings
      es_index_name: str

      es_settings: Dict[str, Any] = field(default_factory=dict)
  
  
  class ConfigurationError(Exception):
      """Raised when configuration validation fails."""
      pass
  
  
  class ConfigLoader:

      """Loads and validates unified search engine configuration from YAML file."""

      def __init__(self, config_file: str = "config/config.yaml"):
          self.config_file = Path(config_file)

      def _load_rewrite_dictionary(self) -> Dict[str, str]:

          """
          Load query rewrite dictionary from external file.
          

          Returns:
              Dictionary mapping query terms to rewritten queries
          """

          # Try config/query_rewrite.dict first
          dict_file = self.config_file.parent / "query_rewrite.dict"

          
          if not dict_file.exists():
              # Dictionary file is optional, return empty dict if not found
              return {}
          
          rewrite_dict = {}
          try:
              with open(dict_file, 'r', encoding='utf-8') as f:
                  for line_num, line in enumerate(f, 1):
                      line = line.strip()
                      # Skip empty lines and comments
                      if not line or line.startswith('#'):
                          continue
                      
                      # Parse tab-separated format
                      parts = line.split('\t')
                      if len(parts) != 2:
                          print(f"Warning: Invalid format in {dict_file} line {line_num}: {line}")
                          continue
                      
                      key, value = parts
                      rewrite_dict[key.strip()] = value.strip()
          except Exception as e:
              print(f"Error loading rewrite dictionary from {dict_file}: {e}")
              return {}
          
          return rewrite_dict

      def load_config(self, validate: bool = True) -> SearchConfig:

          """

          Load unified configuration from YAML file.

          Args:
              validate: Whether to validate configuration after loading (default: True)
  

          Returns:

              SearchConfig object

  
          Raises:

              ConfigurationError: If config file not found, invalid, or validation fails

          """

          if not self.config_file.exists():
              raise ConfigurationError(f"Configuration file not found: {self.config_file}")

  
          try:

              with open(self.config_file, 'r', encoding='utf-8') as f:

                  config_data = yaml.safe_load(f)
          except yaml.YAMLError as e:

              raise ConfigurationError(f"Invalid YAML in {self.config_file}: {e}")

          config = self._parse_config(config_data)
          
          # Auto-validate configuration
          if validate:
              errors = self.validate_config(config)
              if errors:
                  error_msg = "Configuration validation failed:\n" + "\n".join(f"  - {err}" for err in errors)
                  raise ConfigurationError(error_msg)
          
          return config

      def _parse_config(self, config_data: Dict[str, Any]) -> SearchConfig:
          """Parse configuration dictionary into SearchConfig object."""

  
          # Parse fields
          fields = []
          for field_data in config_data.get("fields", []):
              fields.append(self._parse_field_config(field_data))
  
          # Parse indexes
          indexes = []
          for index_data in config_data.get("indexes", []):
              indexes.append(self._parse_index_config(index_data))
  
          # Parse query config
          query_config_data = config_data.get("query_config", {})

          
          # Load rewrite dictionary from external file instead of config

          rewrite_dictionary = self._load_rewrite_dictionary()

          # Auto-collect source_fields from field configs if not explicitly specified
          source_fields = query_config_data.get("source_fields")
          if source_fields is None:
              # Auto-collect fields with return_in_source=True
              source_fields = [
                  field.name for field in fields 
                  if field.return_in_source
              ]
          

          # Parse embedding disable thresholds
          embedding_thresholds = query_config_data.get("embedding_disable_thresholds", {})
          

          query_config = QueryConfig(

              supported_languages=query_config_data.get("supported_languages") or ["zh", "en"],
              default_language=query_config_data.get("default_language") or "zh",

              enable_translation=query_config_data.get("enable_translation", True),
              enable_text_embedding=query_config_data.get("enable_text_embedding", True),
              enable_query_rewrite=query_config_data.get("enable_query_rewrite", True),

              rewrite_dictionary=rewrite_dictionary,

              translation_api_key=query_config_data.get("translation_api_key"),

              translation_service=query_config_data.get("translation_service") or "deepl",

              translation_glossary_id=query_config_data.get("translation_glossary_id"),

              translation_context=query_config_data.get("translation_context") or "e-commerce product search",

              text_embedding_field=query_config_data.get("text_embedding_field"),

              image_embedding_field=query_config_data.get("image_embedding_field"),

              embedding_disable_chinese_char_limit=embedding_thresholds.get("chinese_char_limit", 4),
              embedding_disable_english_word_limit=embedding_thresholds.get("english_word_limit", 3),

              source_fields=source_fields

          )
  
          # Parse ranking config
          ranking_data = config_data.get("ranking", {})
          ranking = RankingConfig(

              expression=ranking_data.get("expression") or "bm25() + 0.2*text_embedding_relevance()",
              description=ranking_data.get("description") or "Default BM25 + text embedding ranking"

          )
  

          # Parse Function Score configuration
          fs_data = config_data.get("function_score", {})
          function_score = FunctionScoreConfig(

              score_mode=fs_data.get("score_mode") or "sum",
              boost_mode=fs_data.get("boost_mode") or "multiply",
              functions=fs_data.get("functions") or []

          )
  
          # Parse Rerank configuration
          rerank_data = config_data.get("rerank", {})
          rerank = RerankConfig(
              enabled=rerank_data.get("enabled", False),

              expression=rerank_data.get("expression") or "",
              description=rerank_data.get("description") or ""

          )
  

          # Parse SPU config
          spu_data = config_data.get("spu_config", {})
          spu_config = SPUConfig(
              enabled=spu_data.get("enabled", False),
              spu_field=spu_data.get("spu_field"),
              inner_hits_size=spu_data.get("inner_hits_size", 3)
          )
  

          return SearchConfig(

              fields=fields,
              indexes=indexes,
              query_config=query_config,
              ranking=ranking,

              function_score=function_score,
              rerank=rerank,

              spu_config=spu_config,

              es_index_name=config_data.get("es_index_name", "search_products"),

              es_settings=config_data.get("es_settings", {})
          )
  
      def _parse_field_config(self, field_data: Dict[str, Any]) -> FieldConfig:
          """Parse field configuration from dictionary."""
          name = field_data["name"]
          field_type_str = field_data["type"]

          field_type_raw = field_type_str

  
          # Map field type string to enum
          if field_type_str not in FIELD_TYPE_MAP:
              raise ConfigurationError(f"Unknown field type: {field_type_str}")
          field_type = FIELD_TYPE_MAP[field_type_str]

          is_hktext = field_type_str.lower() == "hktext"

  
          # Map analyzer string to enum (if provided)
          analyzer = None
          analyzer_str = field_data.get("analyzer")
          if analyzer_str and analyzer_str in ANALYZER_MAP:
              analyzer = ANALYZER_MAP[analyzer_str]
  
          search_analyzer = None
          search_analyzer_str = field_data.get("search_analyzer")
          if search_analyzer_str and search_analyzer_str in ANALYZER_MAP:
              search_analyzer = ANALYZER_MAP[search_analyzer_str]
  
          return FieldConfig(
              name=name,
              field_type=field_type,

              analyzer=analyzer,
              search_analyzer=search_analyzer,
              required=field_data.get("required", False),
              multi_language=field_data.get("multi_language", False),
              languages=field_data.get("languages"),

              return_in_source=field_data.get("return_in_source", True),  # Default to True

              boost=field_data.get("boost", 1.0),
              store=field_data.get("store", False),
              index=field_data.get("index", True),
              embedding_dims=field_data.get("embedding_dims", 1024),
              embedding_similarity=field_data.get("embedding_similarity", "dot_product"),
              nested=field_data.get("nested", False),

              nested_properties=field_data.get("nested_properties"),
              keyword_subfield=field_data.get("keyword_subfield", is_hktext),

              keyword_ignore_above=field_data.get("keyword_ignore_above", 256),
              keyword_normalizer=field_data.get("keyword_normalizer")

          )
  
      def _parse_index_config(self, index_data: Dict[str, Any]) -> IndexConfig:
          """Parse index configuration from dictionary."""
          analyzer_str = index_data.get("analyzer", "chinese_ecommerce")
          if analyzer_str not in ANALYZER_MAP:
              raise ConfigurationError(f"Unknown analyzer: {analyzer_str}")
  

          # Parse language field mapping if present
          language_field_mapping = index_data.get("language_field_mapping")
  

          return IndexConfig(
              name=index_data["name"],
              label=index_data.get("label", index_data["name"]),
              fields=index_data["fields"],
              analyzer=ANALYZER_MAP[analyzer_str],
              boost=index_data.get("boost", 1.0),

              example=index_data.get("example"),
              language_field_mapping=language_field_mapping

          )
  

      def validate_config(self, config: SearchConfig) -> List[str]:

          """

          Validate search configuration.

  
          Args:

              config: Search configuration to validate

  
          Returns:
              List of validation error messages (empty if valid)
          """
          errors = []
  
          # Validate field references in indexes
          field_names = {field.name for field in config.fields}

          field_map = {field.name: field for field in config.fields}
          

          for index in config.indexes:

              # Validate fields in index.fields

              for field_name in index.fields:
                  if field_name not in field_names:
                      errors.append(f"Index '{index.name}' references unknown field '{field_name}'")

              
              # Validate language_field_mapping if present
              if index.language_field_mapping:
                  for lang, field_list in index.language_field_mapping.items():
                      if not isinstance(field_list, list):
                          errors.append(f"Index '{index.name}': language_field_mapping['{lang}'] must be a list")
                          continue
                      
                      for field_name in field_list:
                          # Check if field exists
                          if field_name not in field_names:
                              errors.append(
                                  f"Index '{index.name}': language_field_mapping['{lang}'] "
                                  f"references unknown field '{field_name}'"
                              )
                          else:
                              # Check if field is TEXT type (multi-language fields should be text fields)
                              field = field_map[field_name]
                              if field.field_type != FieldType.TEXT:
                                  errors.append(
                                      f"Index '{index.name}': language_field_mapping['{lang}'] "
                                      f"field '{field_name}' must be of type TEXT, got {field.field_type.value}"
                                  )
                              
                              # Verify analyzer is appropriate for the language
                              # This is a soft check - we just warn if analyzer doesn't match language
                              if field.analyzer:
                                  analyzer_name = field.analyzer.value.lower()
                                  expected_analyzers = {
                                      'zh': ['chinese', 'index_ansj', 'query_ansj'],
                                      'en': ['english'],
                                      'ru': ['russian'],
                                      'ar': ['arabic'],
                                      'es': ['spanish'],
                                      'ja': ['japanese']
                                  }
                                  if lang in expected_analyzers:
                                      expected = expected_analyzers[lang]
                                      if not any(exp in analyzer_name for exp in expected):
                                          # Warning only, not an error
                                          print(
                                              f"Warning: Index '{index.name}': field '{field_name}' for language '{lang}' "
                                              f"uses analyzer '{analyzer_name}', which may not be optimal for '{lang}'"
                                          )

  
          # Validate SPU config
          if config.spu_config.enabled:
              if not config.spu_config.spu_field:
                  errors.append("SPU aggregation enabled but no spu_field specified")
              elif config.spu_config.spu_field not in field_names:
                  errors.append(f"SPU field '{config.spu_config.spu_field}' not found in fields")
  
          # Validate embedding fields have proper configuration
          for field in config.fields:
              if field.field_type in [FieldType.TEXT_EMBEDDING, FieldType.IMAGE_EMBEDDING]:
                  if field.embedding_dims <= 0:
                      errors.append(f"Field '{field.name}': embedding_dims must be positive")
                  if field.embedding_similarity not in ["dot_product", "cosine", "l2_norm"]:
                      errors.append(f"Field '{field.name}': invalid embedding_similarity")
  

          # Validate tenant_id field (required)
          tenant_id_field = None
          for field in config.fields:
              if field.name == "tenant_id":
                  tenant_id_field = field
                  break
          
          if not tenant_id_field:
              errors.append("Required field 'tenant_id' not found in fields")
          elif not tenant_id_field.required:
              errors.append("Field 'tenant_id' must be marked as required")

  
          return errors
  

      def save_config(self, config: SearchConfig, output_path: Optional[str] = None) -> None:

          """

          Save configuration to YAML file.

          
          Note: rewrite_dictionary is saved separately to query_rewrite.dict file

  
          Args:
              config: Configuration to save

              output_path: Optional output path (defaults to config/config.yaml)

          """
          if output_path is None:

              output_path = self.config_file
          else:
              output_path = Path(output_path)

  
          # Convert config back to dictionary format

          query_config_dict = {
              "supported_languages": config.query_config.supported_languages,
              "default_language": config.query_config.default_language,
              "enable_translation": config.query_config.enable_translation,
              "enable_text_embedding": config.query_config.enable_text_embedding,
              "enable_query_rewrite": config.query_config.enable_query_rewrite,
              "translation_service": config.query_config.translation_service,
          }
          
          # Add optional fields only if they are set
          if config.query_config.translation_api_key:
              query_config_dict["translation_api_key"] = config.query_config.translation_api_key
          if config.query_config.translation_glossary_id:
              query_config_dict["translation_glossary_id"] = config.query_config.translation_glossary_id
          if config.query_config.translation_context:
              query_config_dict["translation_context"] = config.query_config.translation_context
          if config.query_config.text_embedding_field:
              query_config_dict["text_embedding_field"] = config.query_config.text_embedding_field
          if config.query_config.image_embedding_field:
              query_config_dict["image_embedding_field"] = config.query_config.image_embedding_field
          if config.query_config.source_fields:
              query_config_dict["source_fields"] = config.query_config.source_fields
          
          # Add embedding disable thresholds
          if (config.query_config.embedding_disable_chinese_char_limit != 4 or 
              config.query_config.embedding_disable_english_word_limit != 3):
              query_config_dict["embedding_disable_thresholds"] = {
                  "chinese_char_limit": config.query_config.embedding_disable_chinese_char_limit,
                  "english_word_limit": config.query_config.embedding_disable_english_word_limit
              }
          

          config_dict = {

              "es_index_name": config.es_index_name,
              "es_settings": config.es_settings,
              "fields": [self._field_to_dict(field) for field in config.fields],
              "indexes": [self._index_to_dict(index) for index in config.indexes],

              "query_config": query_config_dict,

              "ranking": {
                  "expression": config.ranking.expression,
                  "description": config.ranking.description
              },

              "function_score": {
                  "score_mode": config.function_score.score_mode,
                  "boost_mode": config.function_score.boost_mode,
                  "functions": config.function_score.functions
              },
              "rerank": {
                  "enabled": config.rerank.enabled,
                  "expression": config.rerank.expression,
                  "description": config.rerank.description
              },

              "spu_config": {
                  "enabled": config.spu_config.enabled,
                  "spu_field": config.spu_config.spu_field,
                  "inner_hits_size": config.spu_config.inner_hits_size
              }
          }
  

          output_path.parent.mkdir(parents=True, exist_ok=True)

          with open(output_path, 'w', encoding='utf-8') as f:
              yaml.dump(config_dict, f, default_flow_style=False, allow_unicode=True)

          
          # Save rewrite dictionary to separate file

          self._save_rewrite_dictionary(config.query_config.rewrite_dictionary)

      def _save_rewrite_dictionary(self, rewrite_dict: Dict[str, str]) -> None:

          """
          Save rewrite dictionary to external file.
          
          Args:

              rewrite_dict: Dictionary to save
          """

          dict_file = self.config_file.parent / "query_rewrite.dict"
          dict_file.parent.mkdir(parents=True, exist_ok=True)

          
          with open(dict_file, 'w', encoding='utf-8') as f:
              for key, value in rewrite_dict.items():
                  f.write(f"{key}\t{value}\n")

  
      def _field_to_dict(self, field: FieldConfig) -> Dict[str, Any]:

          """Convert FieldConfig to dictionary, preserving all fields."""

          result = {
              "name": field.name,
              "type": field.field_type.value,

              "required": field.required,
              "boost": field.boost,
              "store": field.store,
              "index": field.index,

              "return_in_source": field.return_in_source,

          }
  

          # Add optional fields only if they differ from defaults or are set

          if field.analyzer:
              result["analyzer"] = field.analyzer.value
          if field.search_analyzer:
              result["search_analyzer"] = field.search_analyzer.value
          if field.multi_language:
              result["multi_language"] = field.multi_language

              if field.languages:
                  result["languages"] = field.languages

          if field.embedding_dims != 1024:
              result["embedding_dims"] = field.embedding_dims
          if field.embedding_similarity != "dot_product":
              result["embedding_similarity"] = field.embedding_similarity
          if field.nested:
              result["nested"] = field.nested

              if field.nested_properties:
                  result["nested_properties"] = field.nested_properties
          if field.keyword_subfield:
              result["keyword_subfield"] = field.keyword_subfield
              if field.keyword_ignore_above != 256:
                  result["keyword_ignore_above"] = field.keyword_ignore_above
              if field.keyword_normalizer:
                  result["keyword_normalizer"] = field.keyword_normalizer

  
          return result
  
      def _index_to_dict(self, index: IndexConfig) -> Dict[str, Any]:

          """Convert IndexConfig to dictionary, preserving all fields."""

          result = {

              "name": index.name,
              "label": index.label,
              "fields": index.fields,
              "analyzer": index.analyzer.value,

          }

          
          # Add optional fields only if they differ from defaults or are set
          if index.boost != 1.0:
              result["boost"] = index.boost
          if index.example:
              result["example"] = index.example

          if index.language_field_mapping:
              result["language_field_mapping"] = index.language_field_mapping
  
          return result