from qgis.core import QgsApplication, QgsProject, QgsUserProfileManager, QgsUserProfile, QgsMessageLog, Qgis
import os, sys
import json

# Re-export get_optimization_thresholds for backward compatibility
# Function was moved to core.optimization.config_provider in EPIC-1 Phase E7.5
from filter_mate.core.optimization.config_provider import get_optimization_thresholds

ENV_VARS = {}

# Minimal hardcoded fallback configuration
# Used when all config files are inaccessible or corrupted
FALLBACK_CONFIG = {
    "_CONFIG_VERSION": "2.0",
    "_CONFIG_META": {
        "description": "FilterMate Fallback Configuration (in-memory)",
        "version": "2.0",
        "fallback": True
    },
    "APP": {
        "AUTO_ACTIVATE": {
            "value": False,
            "description": "Auto-activate plugin when a project with vector layers is loaded"
        },
        "DOCKWIDGET": {
            "FEEDBACK_LEVEL": {
                "value": "normal",
                "choices": ["minimal", "normal", "verbose"],
                "description": "User feedback verbosity level"
            },
            "LANGUAGE": {
                "value": "auto",
                "description": "Interface language"
            },
            "THEME": {
                "value": "auto",
                "choices": ["auto", "light", "dark"],
                "description": "UI theme"
            }
        },
        "OPTIONS": {
            "APP_SQLITE_PATH": "",
            "FRESH_RELOAD_FLAG": False
        }
    },
    "POSTGRESQL": {
        "FILTER": {
            "MATERIALIZED_VIEW": {
                "value": True,
                "description": "Use materialized views for filtering"
            }
        }
    }
}


def get_fallback_config():
    """
    Return a deep copy of the fallback configuration.
    
    This is used when all configuration files fail to load.
    The plugin will continue to work with minimal/default settings.
    
    Returns:
        dict: A copy of FALLBACK_CONFIG
    """
    import copy
    return copy.deepcopy(FALLBACK_CONFIG)


def merge(a, b, path=None):
    "merges b into a"
    if path is None: path = []
    for key in b:
        if key in a:
            if isinstance(a[key], dict) and isinstance(b[key], dict):
                merge(a[key], b[key], path + [str(key)])
            elif a[key] == b[key]:
                pass # same leaf value

        else:
            a[key] = b[key]
    return a


def init_env_vars():
    """
    Initialize environment variables and configuration paths.
    
    Now reads config.json from PLUGIN_CONFIG_DIRECTORY (same as SQLite database)
    instead of the plugin directory. If config.json doesn't exist there,
    copies config.default.json from the plugin directory.
    
    Automatically detects and migrates/resets obsolete configurations.
    """
    from qgis.core import QgsMessageLog
    
    PROJECT = QgsProject.instance()
    PLATFORM = sys.platform

    # Plugin directory (where config.default.json is located)
    DIR_CONFIG = os.path.normpath(os.path.dirname(__file__))
    PATH_ABSOLUTE_PROJECT = os.path.normpath(PROJECT.readPath("./"))
    if PATH_ABSOLUTE_PROJECT =='./':
        if PLATFORM.startswith('win'):
            PATH_ABSOLUTE_PROJECT =  os.path.normpath(os.path.join(os.path.join(os.environ['USERPROFILE']), 'Desktop'))
        else:
            PATH_ABSOLUTE_PROJECT =  os.path.normpath(os.environ['HOME'])

    QGIS_SETTINGS_PATH = QgsApplication.qgisSettingsDirPath()
    # Remove trailing separator if present
    QGIS_SETTINGS_PATH = QGIS_SETTINGS_PATH.rstrip(os.sep).rstrip('/')
    
    # Start with default PLUGIN_CONFIG_DIRECTORY
    PLUGIN_CONFIG_DIRECTORY = os.path.normpath(os.path.join(QGIS_SETTINGS_PATH, 'FilterMate'))
    
    # Create the plugin config directory if it doesn't exist
    if not os.path.isdir(PLUGIN_CONFIG_DIRECTORY):
        try:
            os.makedirs(PLUGIN_CONFIG_DIRECTORY, exist_ok=True)
            QgsMessageLog.logMessage(
                f"Created plugin config directory: {PLUGIN_CONFIG_DIRECTORY}",
                "FilterMate",
                Qgis.Info
            )
        except OSError as error:
            QgsMessageLog.logMessage(
                f"Could not create config directory {PLUGIN_CONFIG_DIRECTORY}: {error}",
                "FilterMate",
                Qgis.Critical
            )
    
    # Path to config.json in PLUGIN_CONFIG_DIRECTORY
    config_json_path = os.path.join(PLUGIN_CONFIG_DIRECTORY, 'config.json')
    config_default_path = os.path.join(DIR_CONFIG, 'config.default.json')
    
    # If config.json doesn't exist in PLUGIN_CONFIG_DIRECTORY, copy default first
    if not os.path.exists(config_json_path):
        try:
            import shutil
            shutil.copy2(config_default_path, config_json_path)
            QgsMessageLog.logMessage(
                f"FilterMate: Configuration créée avec les valeurs par défaut",
                "FilterMate",
                Qgis.Info
            )
        except Exception as e:
            QgsMessageLog.logMessage(
                f"FilterMate: Impossible de copier la configuration par défaut: {e}",
                "FilterMate",
                Qgis.Warning
            )
            # Fallback: use config.json from plugin directory
            config_json_path = os.path.join(DIR_CONFIG, 'config.json')
    
    # Load configuration
    CONFIG_DATA = None
    using_fallback = False
    
    try:
        with open(config_json_path) as f:
            CONFIG_DATA = json.load(f)
        
        # v4.0.7: Validate configuration after loading
        try:
            from .config_validator import validate_and_log
            validate_and_log(CONFIG_DATA, DIR_CONFIG)
        except ImportError:
            pass  # Validator not available, skip validation
        except Exception as validation_error:
            QgsMessageLog.logMessage(
                f"FilterMate: Configuration validation skipped: {validation_error}",
                "FilterMate",
                Qgis.Info
            )
            
    except Exception as e:
        QgsMessageLog.logMessage(
            f"Failed to load config from {config_json_path}: {e}",
            "FilterMate",
            Qgis.Warning
        )
        # Try to load default config as second option
        try:
            with open(config_default_path) as f:
                CONFIG_DATA = json.load(f)
            QgsMessageLog.logMessage(
                "FilterMate: Loaded default configuration file",
                "FilterMate",
                Qgis.Info
            )
        except Exception as e2:
            QgsMessageLog.logMessage(
                f"Failed to load default config: {e2}. Using in-memory fallback configuration.",
                "FilterMate",
                Qgis.Warning
            )
            # Ultimate fallback: use hardcoded minimal config
            CONFIG_DATA = get_fallback_config()
            using_fallback = True
    
    # Validate that CONFIG_DATA has the expected structure
    # Support both uppercase (config.default.json) and lowercase (migrated config.json) keys
    has_app_config = isinstance(CONFIG_DATA, dict) and ("APP" in CONFIG_DATA or "app" in CONFIG_DATA)
    if not has_app_config:
        QgsMessageLog.logMessage(
            f"FilterMate: Configuration invalide détectée, utilisation de la configuration de secours",
            "FilterMate",
            Qgis.Warning
        )
        # Use hardcoded fallback instead of raising
        CONFIG_DATA = get_fallback_config()
        using_fallback = True
        
        # Try to write fallback to disk for next time
        try:
            with open(config_json_path, 'w') as outfile:
                outfile.write(json.dumps(CONFIG_DATA, indent=4))
            QgsMessageLog.logMessage(
                f"FilterMate: Configuration de secours sauvegardée: {config_json_path}",
                "FilterMate",
                Qgis.Info
            )
        except Exception as e:
            QgsMessageLog.logMessage(
                f"FilterMate: Impossible de sauvegarder la configuration de secours: {e}",
                "FilterMate",
                Qgis.Warning
            )
    
    # Log if using fallback configuration
    if using_fallback:
        QgsMessageLog.logMessage(
            "FilterMate: Plugin démarré avec configuration de secours. "
            "Certains paramètres peuvent être réinitialisés aux valeurs par défaut.",
            "FilterMate",
            Qgis.Warning
        )

    # Ensure OPTIONS exists in APP (support both uppercase and lowercase keys)
    app_key = "APP" if "APP" in CONFIG_DATA else "app"
    if app_key not in CONFIG_DATA:
        CONFIG_DATA[app_key] = {}
    if "OPTIONS" not in CONFIG_DATA.get(app_key, {}):
        CONFIG_DATA[app_key]["OPTIONS"] = {"APP_SQLITE_PATH": "", "FRESH_RELOAD_FLAG": False}

    # Validate APP_SQLITE_PATH from config
    app_sqlite_path = CONFIG_DATA.get(app_key, {}).get("OPTIONS", {}).get("APP_SQLITE_PATH", "")
    if app_sqlite_path != '':
        configured_path = os.path.normpath(app_sqlite_path)
        
        # Validate that parent directories exist and are accessible
        parent_dir = os.path.dirname(configured_path)
        path_is_valid = False
        
        if parent_dir and os.path.exists(parent_dir):
            # Check if parent directory is accessible
            try:
                if os.access(parent_dir, os.W_OK):
                    path_is_valid = True
                else:
                    QgsMessageLog.logMessage(
                        f"Configured path parent directory is not writable: {parent_dir}. Using default profile.",
                        "FilterMate",
                        Qgis.Warning
                    )
            except Exception as e:
                QgsMessageLog.logMessage(
                    f"Cannot access configured path: {configured_path}. Error: {e}. Using default profile.",
                    "FilterMate",
                    Qgis.Warning
                )
        else:
            QgsMessageLog.logMessage(
                f"Configured path parent directory does not exist: {parent_dir}. Using default profile.",
                "FilterMate",
                Qgis.Warning
            )
        
        if path_is_valid:
            PLUGIN_CONFIG_DIRECTORY = configured_path
            # Update config_json_path if directory changed
            config_json_path = os.path.join(PLUGIN_CONFIG_DIRECTORY, 'config.json')
    
    # Update APP_SQLITE_PATH in config if needed
    current_sqlite_path = CONFIG_DATA.get(app_key, {}).get("OPTIONS", {}).get("APP_SQLITE_PATH", "")
    if current_sqlite_path != PLUGIN_CONFIG_DIRECTORY:
        CONFIG_DATA[app_key]["OPTIONS"]["APP_SQLITE_PATH"] = PLUGIN_CONFIG_DIRECTORY
        try:
            with open(config_json_path, 'w') as outfile:
                outfile.write(json.dumps(CONFIG_DATA, indent=4))
        except Exception as e:
            QgsMessageLog.logMessage(
                f"Could not update config.json with path: {e}",
                "FilterMate",
                Qgis.Warning
            )

    global ENV_VARS
    ENV_VARS["PROJECT"] = PROJECT
    ENV_VARS["PLATFORM"] = PLATFORM
    ENV_VARS["DIR_CONFIG"] = DIR_CONFIG
    ENV_VARS["PATH_ABSOLUTE_PROJECT"] = PATH_ABSOLUTE_PROJECT
    ENV_VARS["CONFIG_DATA"] = CONFIG_DATA
    ENV_VARS["QGIS_SETTINGS_PATH"] = QGIS_SETTINGS_PATH
    ENV_VARS["PLUGIN_CONFIG_DIRECTORY"] = PLUGIN_CONFIG_DIRECTORY
    ENV_VARS["CONFIG_JSON_PATH"] = config_json_path  # Store active config path


def reset_config_to_default():
    """
    Reset configuration to default by copying config.default.json 
    to the active config location (PLUGIN_CONFIG_DIRECTORY/config.json).
    
    Use this when reinitializing the config and SQLite database.
    
    Returns:
        bool: True if reset successful, False otherwise
    """
    try:
        import shutil
        
        if "DIR_CONFIG" not in ENV_VARS or "CONFIG_JSON_PATH" not in ENV_VARS:
            QgsMessageLog.logMessage(
                "Environment variables not initialized. Call init_env_vars() first.",
                "FilterMate",
                Qgis.Critical
            )
            return False
        
        config_default_path = os.path.join(ENV_VARS["DIR_CONFIG"], 'config.default.json')
        config_json_path = ENV_VARS["CONFIG_JSON_PATH"]
        
        # Backup existing config if it exists
        if os.path.exists(config_json_path):
            backup_path = config_json_path + '.backup'
            shutil.copy2(config_json_path, backup_path)
            QgsMessageLog.logMessage(
                f"Backed up existing config to: {backup_path}",
                "FilterMate",
                Qgis.Info
            )
        
        # Copy default config
        shutil.copy2(config_default_path, config_json_path)
        
        # Reload config
        with open(config_json_path) as f:
            ENV_VARS["CONFIG_DATA"] = json.load(f)
        
        QgsMessageLog.logMessage(
            f"Configuration reset to default: {config_json_path}",
            "FilterMate",
            Qgis.Info
        )
        
        return True
        
    except Exception as e:
        QgsMessageLog.logMessage(
            f"Failed to reset configuration: {e}",
            "FilterMate",
            Qgis.Critical
        )
        return False


def reload_config():
    """
    Reload configuration from config.json file.
    
    Use this to apply configuration changes without restarting QGIS.
    Updates ENV_VARS['CONFIG_DATA'] with latest values from disk.
    
    If environment variables are not initialized, calls init_env_vars() first.
    
    Returns:
        bool: True if reload successful, False otherwise
    """
    global ENV_VARS
    
    try:
        config_json_path = ENV_VARS.get("CONFIG_JSON_PATH")
        
        # If CONFIG_JSON_PATH not set, initialize environment first
        if not config_json_path:
            init_env_vars()
            config_json_path = ENV_VARS.get("CONFIG_JSON_PATH")
        
        if not config_json_path or not os.path.exists(config_json_path):
            QgsMessageLog.logMessage(
                f"Config file not found: {config_json_path}",
                "FilterMate",
                Qgis.Warning
            )
            return False
        
        with open(config_json_path, 'r', encoding='utf-8') as f:
            new_config = json.load(f)
        
        ENV_VARS["CONFIG_DATA"] = new_config
        
        QgsMessageLog.logMessage(
            f"Configuration reloaded from: {config_json_path}",
            "FilterMate",
            Qgis.Info  # DEBUG
        )
        
        return True
        
    except Exception as e:
        QgsMessageLog.logMessage(
            f"Failed to reload configuration: {e}",
            "FilterMate",
            Qgis.Critical
        )
        return False
