import json
import os
from typing import List, Dict, Any, Optional, Union
import logging

logger = logging.getLogger(__name__)

class DatabaseConnector:
    """
    A connector for JSON-based data storage.
    Provides generic database operations with tenant and user context support.
    """
    def __init__(self, dbHost: str, dbDatabase: str, dbUser: str = None, dbPassword: str = None, 
                mandateId: int = None, userId: int = None, skipInitialIdLookup: bool = False):
        """
        Initializes the JSON database connector.
        
        Args:
            dbHost: Directory for the JSON files
            dbDatabase: Database name
            dbUser: Username for authentication (optional)
            dbPassword: API key for authentication (optional)
            mandateId: Context parameter for the tenant
            userId: Context parameter for the user
            skipInitialIdLookup: When True, skips looking up initial IDs for mandateId and userId
        """
        # Store the input parameters
        self.dbHost = dbHost
        self.dbDatabase = dbDatabase
        self.dbUser = dbUser
        self.dbPassword = dbPassword
        self.skipInitialIdLookup = skipInitialIdLookup
        
        # Check if context parameters are set
        if mandateId is None or userId is None:
            raise ValueError("mandateId and userId must be set")
        
        # Ensure the database directory exists
        self.dbFolder = os.path.join(self.dbHost, self.dbDatabase)
        os.makedirs(self.dbFolder, exist_ok=True)
        
        # Cache for loaded data
        self._tablesCache = {}
        
        # Initialize system table
        self._systemTableName = "_system"
        self._initializeSystemTable()
        
        # Temporarily store mandateId and userId
        self._mandateId = mandateId
        self._userId = userId
        
        # If mandateId or userId are 0 and we're not skipping ID lookup, try to use the initial IDs
        if not skipInitialIdLookup:
            if mandateId == 0:
                initialMandateId = self.getInitialId("mandates")
                if initialMandateId is not None:
                    self._mandateId = initialMandateId
                    logger.info(f"Using initial mandateId: {initialMandateId} instead of 0")
            
            if userId == 0:
                initialUserId = self.getInitialId("users")
                if initialUserId is not None:
                    self._userId = initialUserId
                    logger.info(f"Using initial userId: {initialUserId} instead of 0")
        
        # Set the effective IDs as properties
        self.mandateId = self._mandateId
        self.userId = self._userId
        
        logger.info(f"DatabaseConnector initialized for directory: {self.dbFolder}")
        logger.debug(f"Context: mandateId={self.mandateId}, userId={self.userId}")
    
    def _initializeSystemTable(self):
        """Initializes the system table if it doesn't exist yet."""
        systemTablePath = self._getTablePath(self._systemTableName)
        if not os.path.exists(systemTablePath):
            emptySystemTable = {}
            self._saveSystemTable(emptySystemTable)
            logger.info(f"System table initialized in {systemTablePath}")
        else:
            # Load existing system table to ensure it's available
            self._loadSystemTable()
            logger.debug(f"Existing system table loaded from {systemTablePath}")
            
    def _loadSystemTable(self) -> Dict[str, int]:
        """Loads the system table with the initial IDs."""
        # Check if system table is in cache
        if f"_{self._systemTableName}" in self._tablesCache:
            return self._tablesCache[f"_{self._systemTableName}"]
            
        systemTablePath = self._getTablePath(self._systemTableName)
        try:
            if os.path.exists(systemTablePath):
                with open(systemTablePath, 'r', encoding='utf-8') as f:
                    data = json.load(f)
                    # Store in cache with special prefix to avoid collision with regular tables
                    self._tablesCache[f"_{self._systemTableName}"] = data
                    return data
            else:
                self._tablesCache[f"_{self._systemTableName}"] = {}
                return {}
        except Exception as e:
            logger.error(f"Error loading the system table: {e}")
            self._tablesCache[f"_{self._systemTableName}"] = {}
            return {}
    
    def _saveSystemTable(self, data: Dict[str, int]) -> bool:
        """Saves the system table with the initial IDs."""
        systemTablePath = self._getTablePath(self._systemTableName)
        try:
            with open(systemTablePath, 'w', encoding='utf-8') as f:
                json.dump(data, f, indent=2, ensure_ascii=False)
            # Update cache
            self._tablesCache[f"_{self._systemTableName}"] = data
            return True
        except Exception as e:
            logger.error(f"Error saving the system table: {e}")
            return False
    
    def _getTablePath(self, table: str) -> str:
        """Returns the full path to a table file"""
        return os.path.join(self.dbFolder, f"{table}.json")
    
    def _loadTable(self, table: str) -> List[Dict[str, Any]]:
        """Loads a table from the corresponding JSON file"""
        path = self._getTablePath(table)
        
        # If the table is the system table, load it directly
        if table == self._systemTableName:
            return []  # The system table is not treated like normal tables
        
        # If the table is already in the cache, use the cache
        if table in self._tablesCache:
            return self._tablesCache[table]
        
        # Otherwise load the file
        try:
            if os.path.exists(path):
                with open(path, 'r', encoding='utf-8') as f:
                    data = json.load(f)
                    self._tablesCache[table] = data
                    
                    # If data was loaded and no initial ID is registered yet,
                    # register the ID of the first record (if available)
                    if data and not self.hasInitialId(table):
                        if "id" in data[0]:
                            self._registerInitialId(table, data[0]["id"])
                            logger.info(f"Initial ID {data[0]['id']} for table {table} retroactively registered")
                    
                    return data
            else:
                # If the file doesn't exist, create an empty table
                logger.info(f"New table {table}")
                self._tablesCache[table] = []
                self._saveTable(table, [])
                return []
        except Exception as e:
            logger.error(f"Error loading table {table}: {e}")
            return []
    
    def _saveTable(self, table: str, data: List[Dict[str, Any]]) -> bool:
        """Saves a table to the corresponding JSON file"""
        # The system table is handled specially
        if table == self._systemTableName:
            return False
            
        path = self._getTablePath(table)
        try:
            with open(path, 'w', encoding='utf-8') as f:
                json.dump(data, f, indent=2, ensure_ascii=False)
            
            # Update the cache
            self._tablesCache[table] = data
            return True
        except Exception as e:
            logger.error(f"Error saving table {table}: {e}")
            return False
    
    def _filterByContext(self, records: List[Dict[str, Any]]) -> List[Dict[str, Any]]:
        """
        Filters records by tenant and user context,
        if these fields exist in the record.
        """
        filteredRecords = []
        
        for record in records:
            # Check if mandateId exists in the record and is not null
            hasMandate = "mandateId" in record and record["mandateId"] is not None and record["mandateId"] != ""
            
            # Check if userId exists in the record and is not null
            hasUser = "userId" in record and record["userId"] is not None and record["userId"] != ""
            
            # If both exist, filter accordingly
            if hasMandate and hasUser:
                if record["mandateId"] == self.mandateId:
                    filteredRecords.append(record)
            # If only mandateId exists
            elif hasMandate and not hasUser:
                if record["mandateId"] == self.mandateId:
                    filteredRecords.append(record)
            # If neither mandateId nor userId exist, add the record
            elif not hasMandate and not hasUser:
                filteredRecords.append(record)
        
        return filteredRecords
    

    def _applyRecordFilter(self, records: List[Dict[str, Any]], recordFilter: Dict[str, Any] = None) -> List[Dict[str, Any]]:
        """Applies a record filter to the records"""
        if not recordFilter:
            return records
        
        filteredRecords = []
        
        for record in records:
            match = True
            
            for field, value in recordFilter.items():
                # Check if the field exists
                if field not in record:
                    match = False
                    break
                    
                # Handle type conversion for integer comparisons both ways
                if isinstance(value, int) and isinstance(record[field], str) and record[field].isdigit():
                    # Filter value is int, record value is string
                    if value != int(record[field]):
                        match = False
                        break
                elif isinstance(value, str) and value.isdigit() and isinstance(record[field], int):
                    # Filter value is string, record value is int
                    if record[field] != int(value):
                        match = False
                        break
                # Otherwise direct comparison
                elif record[field] != value:
                    match = False
                    break
            
            if match:
                filteredRecords.append(record)
        
        return filteredRecords

    def _registerInitialId(self, table: str, initialId: int) -> bool:
        """
        Registers the initial ID for a table.
        
        Args:
            table: Name of the table
            initialId: The initial ID
            
        Returns:
            True on success, False on error
        """
        try:
            # Load the current system table
            systemData = self._loadSystemTable()
            
            # Only register if not already present
            if table not in systemData:
                systemData[table] = initialId
                success = self._saveSystemTable(systemData)
                if success:
                    logger.info(f"Initial ID {initialId} for table {table} registered")
                return success
            return True  # If already present, this is not an error
        except Exception as e:
            logger.error(f"Error registering the initial ID for table {table}: {e}")
            return False

    def _removeInitialId(self, table: str) -> bool:
        """
        Removes the initial ID for a table from the system table.
        
        Args:
            table: Name of the table
            
        Returns:
            True on success, False on error
        """
        try:
            # Load the current system table
            systemData = self._loadSystemTable()
            
            # Remove the entry if it exists
            if table in systemData:
                del systemData[table]
                success = self._saveSystemTable(systemData)
                if success:
                    logger.info(f"Initial ID for table {table} removed from system table")
                return success
            return True  # If not present, this is not an error
        except Exception as e:
            logger.error(f"Error removing initial ID for table {table}: {e}")
            return False

    # Public API
  
    def getTables(self) -> List[str]:
        """
        Returns a list of all available tables.
            
        Returns:
            List of table names
        """
        tables = []
        
        try:
            for filename in os.listdir(self.dbFolder):
                if filename.endswith('.json') and not filename.startswith('_'):
                    tableName = filename[:-5]  # Remove the .json extension
                    tables.append(tableName)
        except Exception as e:
            logger.error(f"Error reading the database directory: {e}")
        
        return tables
    
    def getFields(self, table: str) -> List[str]:
        """
        Returns a list of all fields in a table.
        
        Args:
            table: Name of the table
            
        Returns:
            List of field names
        """
        # Load the table data
        data = self._loadTable(table)
        
        if not data:
            return []
        
        # Take the first record as a reference for the fields
        fields = list(data[0].keys()) if data else []
        
        return fields
    
    def getSchema(self, table: str, language: str = None) -> Dict[str, Dict[str, Any]]:
        """
        Returns a schema object for a table with data types and labels.
        
        Args:
            table: Name of the table
            language: Language for the labels (optional)
            
        Returns:
            Schema object with fields, data types and labels
        """
        # Load the table data
        data = self._loadTable(table)
        
        schema = {}
        
        if not data:
            return schema
        
        # Take the first record as a reference for the fields and data types
        firstRecord = data[0]
        
        for field, value in firstRecord.items():
            # Determine the data type
            dataType = type(value).__name__
            
            # Create label (default is the field name)
            label = field
            
            schema[field] = {
                "type": dataType,
                "label": label
            }
        
        return schema
    
    def getRecordset(self, table: str, fieldFilter: List[str] = None, recordFilter: Dict[str, Any] = None) -> List[Dict[str, Any]]:
        """
        Returns a list of records from a table, filtered by criteria.
        
        Args:
            table: Name of the table
            fieldFilter: Filter for fields (which fields should be returned)
            recordFilter: Filter for records (which records should be returned)
            
        Returns:
            List of filtered records
        """
        # Load the table data
        data = self._loadTable(table)
        logger.debug(f"getRecordset: data volume of {len(data)} bytes")
        
        # Filter by tenant and user context
        filteredData = self._filterByContext(data)
        
        # Apply recordFilter if available
        if recordFilter:
            filteredData = self._applyRecordFilter(filteredData, recordFilter)
        
        # If fieldFilter is available, reduce the fields
        if fieldFilter and isinstance(fieldFilter, list):
            result = []
            for record in filteredData:
                filteredRecord = {}
                for field in fieldFilter:
                    if field in record:
                        filteredRecord[field] = record[field]
                result.append(filteredRecord)
            return result
        
        return filteredData
    
    def recordCreate(self, table: str, recordData: Dict[str, Any]) -> Dict[str, Any]:
        """
        Creates a new record in the table.
        
        Args:
            table: Name of the table
            recordData: Data for the new record
            
        Returns:
            The created record
        """
        # Load the table data
        data = self._loadTable(table)
        
        # Add mandateId and userId if not present or 0
        if "mandateId" not in recordData or recordData["mandateId"] == 0:
            recordData["mandateId"] = self.mandateId
        
        if "userId" not in recordData or recordData["userId"] == 0:
            recordData["userId"] = self.userId
        
        # Determine the next ID if not present
        if "id" not in recordData:
            nextId = 1
            if data:
                nextId = max(record["id"] for record in data if "id" in record) + 1
            recordData["id"] = nextId
        
        # If the table is empty and a system ID should be registered
        if not data:
            self._registerInitialId(table, recordData["id"])
            logger.info(f"Initial ID {recordData['id']} for table {table} has been registered")
        
        # Add the new record
        data.append(recordData)
        
        # Save the updated table
        if self._saveTable(table, data):
            return recordData
        else:
            raise ValueError(f"Error creating the record in table {table}")

    def recordDelete(self, table: str, recordId: Union[str, int]) -> bool:
        """
        Deletes a record from the table.
        
        Args:
            table: Name of the table
            recordId: ID of the record to delete
            
        Returns:
            True on success, False on error
        """
        # Load table data
        data = self._loadTable(table)
        
        # Search for the record
        for i, record in enumerate(data):
            if "id" in record and record["id"] == recordId:
                # Check if the record belongs to the current mandate
                if "mandateId" in record and record["mandateId"] != self.mandateId:
                    raise ValueError("Not your mandate")
                
                # Check if it's an initial record
                initialId = self.getInitialId(table)
                if initialId is not None and initialId == recordId:
                    # Remove this entry from the system table
                    self._removeInitialId(table)
                    logger.info(f"Initial ID {recordId} for table {table} has been removed from the system table")
                
                # Delete the record
                del data[i]
                
                # Save the updated table
                return self._saveTable(table, data)
        
        # Record not found
        return False

    def recordModify(self, table: str, recordId: Union[str, int], recordData: Dict[str, Any]) -> Dict[str, Any]:
        """
        Modifies a record in the table.
        
        Args:
            table: Name of the table
            recordId: ID of the record to modify
            recordData: New data for the record
            
        Returns:
            The updated record
        """
        # Load table data
        data = self._loadTable(table)
        
        # Search for the record
        for i, record in enumerate(data):
            if "id" in record and record["id"] == recordId:
                # Check if the record belongs to the current mandate
                if "mandateId" in record and record["mandateId"] != self.mandateId:
                    raise ValueError("Not your mandate")
                
                # Prevent changing the ID
                if "id" in recordData and recordData["id"] != recordId:
                    raise ValueError(f"The ID of a record in table {table} cannot be changed")
                
                # Update the record
                for key, value in recordData.items():
                    data[i][key] = value
                
                # Save the updated table
                if self._saveTable(table, data):
                    return data[i]
                else:
                    raise ValueError(f"Error updating record in table {table}")
        
        # Record not found
        raise ValueError(f"Record with ID {recordId} not found in table {table}")

    def hasInitialId(self, table: str) -> bool:
        """
        Checks if an initial ID is registered for a table.
        
        Args:
            table: Name of the table
            
        Returns:
            True if an initial ID is registered, otherwise False
        """
        systemData = self._loadSystemTable()
        return table in systemData
    
    def getInitialId(self, table: str) -> Optional[int]:
        """
        Returns the initial ID for a table.
        
        Args:
            table: Name of the table
            
        Returns:
            The initial ID or None if not present
        """
        systemData = self._loadSystemTable()
        initialId = systemData.get(table)
        logger.debug(f"Database '{self.dbDatabase}': Initial ID for table '{table}' is {initialId}")
        if initialId is None:
            logger.debug(f"No initial ID found for table {table}")
        return initialId
    
    def getAllInitialIds(self) -> Dict[str, int]:
        """
        Returns all registered initial IDs.
        
        Returns:
            Dictionary with table names as keys and initial IDs as values
        """
        systemData = self._loadSystemTable()
        return systemData.copy()  # Return a copy to protect the original