"""
SpecManager Service

Central service for managing AtomizerSpec v2.0.
All spec modifications flow through this service.

Features:
- Load/save specs with validation
- Atomic writes with conflict detection
- Patch operations with JSONPath support
- Node CRUD operations
- Custom function support
- WebSocket broadcast integration
"""

import hashlib
import json
import re
import sys
from datetime import datetime, timezone
from pathlib import Path
from typing import Any, Callable, Dict, List, Optional, Set, Tuple, Union

# Add optimization_engine to path if needed
ATOMIZER_ROOT = Path(__file__).parent.parent.parent.parent.parent
if str(ATOMIZER_ROOT) not in sys.path:
    sys.path.insert(0, str(ATOMIZER_ROOT))

from optimization_engine.config.spec_models import (
    AtomizerSpec,
    DesignVariable,
    Extractor,
    Objective,
    Constraint,
    CanvasPosition,
    CanvasEdge,
    ExtractorType,
    CustomFunction,
    ExtractorOutput,
    ValidationReport,
)
from optimization_engine.config.spec_validator import (
    SpecValidator,
    SpecValidationError,
)


class SpecManagerError(Exception):
    """Base error for SpecManager operations."""
    pass


class SpecNotFoundError(SpecManagerError):
    """Raised when spec file doesn't exist."""
    pass


class SpecConflictError(SpecManagerError):
    """Raised when spec has been modified by another client."""

    def __init__(self, message: str, current_hash: str):
        super().__init__(message)
        self.current_hash = current_hash


class WebSocketSubscriber:
    """Protocol for WebSocket subscribers."""

    async def send_json(self, data: Dict[str, Any]) -> None:
        """Send JSON data to subscriber."""
        raise NotImplementedError


class SpecManager:
    """
    Central service for managing AtomizerSpec.

    All modifications go through this service to ensure:
    - Validation on every change
    - Atomic file writes
    - Conflict detection via hashing
    - WebSocket broadcast to all clients
    """

    SPEC_FILENAME = "atomizer_spec.json"

    def __init__(self, study_path: Union[str, Path]):
        """
        Initialize SpecManager for a study.

        Args:
            study_path: Path to the study directory
        """
        self.study_path = Path(study_path)
        self.spec_path = self.study_path / self.SPEC_FILENAME
        self.validator = SpecValidator()
        self._subscribers: List[WebSocketSubscriber] = []
        self._last_hash: Optional[str] = None

    # =========================================================================
    # Core CRUD Operations
    # =========================================================================

    def load(self, validate: bool = True) -> AtomizerSpec:
        """
        Load and optionally validate the spec.

        Args:
            validate: Whether to validate the spec

        Returns:
            AtomizerSpec instance

        Raises:
            SpecNotFoundError: If spec file doesn't exist
            SpecValidationError: If validation fails
        """
        if not self.spec_path.exists():
            raise SpecNotFoundError(f"Spec not found: {self.spec_path}")

        with open(self.spec_path, 'r', encoding='utf-8') as f:
            data = json.load(f)

        if validate:
            self.validator.validate(data, strict=True)

        spec = AtomizerSpec.model_validate(data)
        self._last_hash = self._compute_hash(data)
        return spec

    def load_raw(self) -> Dict[str, Any]:
        """
        Load spec as raw dict without parsing.

        Returns:
            Raw spec dict

        Raises:
            SpecNotFoundError: If spec file doesn't exist
        """
        if not self.spec_path.exists():
            raise SpecNotFoundError(f"Spec not found: {self.spec_path}")

        with open(self.spec_path, 'r', encoding='utf-8') as f:
            return json.load(f)

    def save(
        self,
        spec: Union[AtomizerSpec, Dict[str, Any]],
        modified_by: str = "api",
        expected_hash: Optional[str] = None
    ) -> str:
        """
        Save spec with validation and broadcast.

        Args:
            spec: Spec to save (AtomizerSpec or dict)
            modified_by: Who/what is making the change
            expected_hash: If provided, verify current file hash matches

        Returns:
            New spec hash

        Raises:
            SpecValidationError: If validation fails
            SpecConflictError: If expected_hash doesn't match current
        """
        # Convert to dict if needed
        if isinstance(spec, AtomizerSpec):
            data = spec.model_dump(mode='json')
        else:
            data = spec

        # Check for conflicts if expected_hash provided
        if expected_hash and self.spec_path.exists():
            current_hash = self.get_hash()
            if current_hash != expected_hash:
                raise SpecConflictError(
                    "Spec was modified by another client",
                    current_hash=current_hash
                )

        # Update metadata
        now = datetime.now(timezone.utc).isoformat().replace('+00:00', 'Z')
        data["meta"]["modified"] = now
        data["meta"]["modified_by"] = modified_by

        # Validate
        self.validator.validate(data, strict=True)

        # Compute new hash
        new_hash = self._compute_hash(data)

        # Atomic write (write to temp, then rename)
        temp_path = self.spec_path.with_suffix('.tmp')
        with open(temp_path, 'w', encoding='utf-8') as f:
            json.dump(data, f, indent=2, ensure_ascii=False)

        temp_path.replace(self.spec_path)

        # Update cached hash
        self._last_hash = new_hash

        # Broadcast to subscribers
        self._broadcast({
            "type": "spec_updated",
            "hash": new_hash,
            "modified_by": modified_by,
            "timestamp": now
        })

        return new_hash

    def exists(self) -> bool:
        """Check if spec file exists."""
        return self.spec_path.exists()

    def get_hash(self) -> str:
        """Get current spec hash."""
        if not self.spec_path.exists():
            return ""
        with open(self.spec_path, 'r', encoding='utf-8') as f:
            data = json.load(f)
        return self._compute_hash(data)

    def validate_and_report(self) -> ValidationReport:
        """
        Run full validation and return detailed report.

        Returns:
            ValidationReport with errors, warnings, summary
        """
        if not self.spec_path.exists():
            raise SpecNotFoundError(f"Spec not found: {self.spec_path}")

        data = self.load_raw()
        return self.validator.validate(data, strict=False)

    # =========================================================================
    # Patch Operations
    # =========================================================================

    def patch(
        self,
        path: str,
        value: Any,
        modified_by: str = "api"
    ) -> AtomizerSpec:
        """
        Apply a JSONPath-style modification.

        Args:
            path: JSONPath like "design_variables[0].bounds.max"
            value: New value to set
            modified_by: Who/what is making the change

        Returns:
            Updated AtomizerSpec
        """
        data = self.load_raw()

        # Validate the partial update
        spec = AtomizerSpec.model_validate(data)
        is_valid, errors = self.validator.validate_partial(path, value, spec)
        if not is_valid:
            raise SpecValidationError(f"Invalid update: {'; '.join(errors)}")

        # Apply the patch
        self._apply_patch(data, path, value)

        # Save and return
        self.save(data, modified_by)
        return self.load(validate=False)

    def _apply_patch(self, data: Dict, path: str, value: Any) -> None:
        """
        Apply a patch to the data dict.

        Supports paths like:
        - "meta.description"
        - "design_variables[0].bounds.max"
        - "objectives[1].weight"
        """
        parts = self._parse_path(path)
        if not parts:
            raise ValueError(f"Invalid path: {path}")

        # Navigate to parent
        current = data
        for part in parts[:-1]:
            if isinstance(current, list):
                idx = int(part)
                current = current[idx]
            else:
                current = current[part]

        # Set final value
        final_key = parts[-1]
        if isinstance(current, list):
            idx = int(final_key)
            current[idx] = value
        else:
            current[final_key] = value

    def _parse_path(self, path: str) -> List[str]:
        """Parse JSONPath into parts."""
        # Handle both dot notation and bracket notation
        parts = []
        for part in re.split(r'\.|\[|\]', path):
            if part:
                parts.append(part)
        return parts

    # =========================================================================
    # Node Operations
    # =========================================================================

    def add_node(
        self,
        node_type: str,
        node_data: Dict[str, Any],
        modified_by: str = "canvas"
    ) -> str:
        """
        Add a new node (design var, extractor, objective, constraint).

        Args:
            node_type: One of 'designVar', 'extractor', 'objective', 'constraint'
            node_data: Node data without ID
            modified_by: Who/what is making the change

        Returns:
            Generated node ID
        """
        data = self.load_raw()

        # Generate ID
        node_id = self._generate_id(node_type, data)
        node_data["id"] = node_id

        # Add canvas position if not provided
        if "canvas_position" not in node_data:
            node_data["canvas_position"] = self._auto_position(node_type, data)

        # Add to appropriate section
        section = self._get_section_for_type(node_type)

        if section not in data or data[section] is None:
            data[section] = []

        data[section].append(node_data)

        self.save(data, modified_by)

        # Broadcast node addition
        self._broadcast({
            "type": "node_added",
            "node_type": node_type,
            "node_id": node_id,
            "modified_by": modified_by
        })

        return node_id

    def update_node(
        self,
        node_id: str,
        updates: Dict[str, Any],
        modified_by: str = "canvas"
    ) -> None:
        """
        Update an existing node.

        Args:
            node_id: ID of the node to update
            updates: Dict of fields to update
            modified_by: Who/what is making the change
        """
        data = self.load_raw()

        # Find and update the node
        found = False
        for section in ["design_variables", "extractors", "objectives", "constraints"]:
            if section not in data or data[section] is None:
                continue
            for node in data[section]:
                if node.get("id") == node_id:
                    node.update(updates)
                    found = True
                    break
            if found:
                break

        if not found:
            raise SpecManagerError(f"Node not found: {node_id}")

        self.save(data, modified_by)

    def remove_node(
        self,
        node_id: str,
        modified_by: str = "canvas"
    ) -> None:
        """
        Remove a node and all edges referencing it.

        Args:
            node_id: ID of the node to remove
            modified_by: Who/what is making the change
        """
        data = self.load_raw()

        # Find and remove node
        removed = False
        for section in ["design_variables", "extractors", "objectives", "constraints"]:
            if section not in data or data[section] is None:
                continue
            original_len = len(data[section])
            data[section] = [n for n in data[section] if n.get("id") != node_id]
            if len(data[section]) < original_len:
                removed = True
                break

        if not removed:
            raise SpecManagerError(f"Node not found: {node_id}")

        # Remove edges referencing this node
        if "canvas" in data and data["canvas"] and "edges" in data["canvas"]:
            data["canvas"]["edges"] = [
                e for e in data["canvas"]["edges"]
                if e.get("source") != node_id and e.get("target") != node_id
            ]

        self.save(data, modified_by)

        # Broadcast node removal
        self._broadcast({
            "type": "node_removed",
            "node_id": node_id,
            "modified_by": modified_by
        })

    def update_node_position(
        self,
        node_id: str,
        position: Dict[str, float],
        modified_by: str = "canvas"
    ) -> None:
        """
        Update a node's canvas position.

        Args:
            node_id: ID of the node
            position: Dict with x, y coordinates
            modified_by: Who/what is making the change
        """
        self.update_node(node_id, {"canvas_position": position}, modified_by)

    def add_edge(
        self,
        source: str,
        target: str,
        modified_by: str = "canvas"
    ) -> None:
        """
        Add a canvas edge between nodes.

        Args:
            source: Source node ID
            target: Target node ID
            modified_by: Who/what is making the change
        """
        data = self.load_raw()

        # Initialize canvas section if needed
        if "canvas" not in data or data["canvas"] is None:
            data["canvas"] = {}
        if "edges" not in data["canvas"] or data["canvas"]["edges"] is None:
            data["canvas"]["edges"] = []

        # Check for duplicate
        for edge in data["canvas"]["edges"]:
            if edge.get("source") == source and edge.get("target") == target:
                return  # Already exists

        data["canvas"]["edges"].append({
            "source": source,
            "target": target
        })

        self.save(data, modified_by)

    def remove_edge(
        self,
        source: str,
        target: str,
        modified_by: str = "canvas"
    ) -> None:
        """
        Remove a canvas edge.

        Args:
            source: Source node ID
            target: Target node ID
            modified_by: Who/what is making the change
        """
        data = self.load_raw()

        if "canvas" in data and data["canvas"] and "edges" in data["canvas"]:
            data["canvas"]["edges"] = [
                e for e in data["canvas"]["edges"]
                if not (e.get("source") == source and e.get("target") == target)
            ]

        self.save(data, modified_by)

    # =========================================================================
    # Custom Function Support
    # =========================================================================

    def add_custom_function(
        self,
        name: str,
        code: str,
        outputs: List[str],
        description: Optional[str] = None,
        modified_by: str = "claude"
    ) -> str:
        """
        Add a custom extractor function.

        Args:
            name: Function name
            code: Python source code
            outputs: List of output names
            description: Optional description
            modified_by: Who/what is making the change

        Returns:
            Generated extractor ID

        Raises:
            SpecValidationError: If Python syntax is invalid
        """
        # Validate Python syntax
        try:
            compile(code, f"<custom:{name}>", "exec")
        except SyntaxError as e:
            raise SpecValidationError(
                f"Invalid Python syntax: {e.msg} at line {e.lineno}"
            )

        data = self.load_raw()

        # Generate extractor ID
        ext_id = self._generate_id("extractor", data)

        # Create extractor
        extractor = {
            "id": ext_id,
            "name": description or f"Custom: {name}",
            "type": "custom_function",
            "builtin": False,
            "function": {
                "name": name,
                "module": "custom_extractors.dynamic",
                "source_code": code
            },
            "outputs": [{"name": o, "metric": "custom"} for o in outputs],
            "canvas_position": self._auto_position("extractor", data)
        }

        data["extractors"].append(extractor)
        self.save(data, modified_by)

        return ext_id

    def update_custom_function(
        self,
        extractor_id: str,
        code: Optional[str] = None,
        outputs: Optional[List[str]] = None,
        modified_by: str = "claude"
    ) -> None:
        """
        Update an existing custom function.

        Args:
            extractor_id: ID of the custom extractor
            code: New Python code (optional)
            outputs: New outputs (optional)
            modified_by: Who/what is making the change
        """
        data = self.load_raw()

        # Find the extractor
        extractor = None
        for ext in data.get("extractors", []):
            if ext.get("id") == extractor_id:
                extractor = ext
                break

        if not extractor:
            raise SpecManagerError(f"Extractor not found: {extractor_id}")

        if extractor.get("type") != "custom_function":
            raise SpecManagerError(f"Extractor {extractor_id} is not a custom function")

        # Update code
        if code is not None:
            try:
                compile(code, f"<custom:{extractor_id}>", "exec")
            except SyntaxError as e:
                raise SpecValidationError(
                    f"Invalid Python syntax: {e.msg} at line {e.lineno}"
                )
            if "function" not in extractor:
                extractor["function"] = {}
            extractor["function"]["source_code"] = code

        # Update outputs
        if outputs is not None:
            extractor["outputs"] = [{"name": o, "metric": "custom"} for o in outputs]

        self.save(data, modified_by)

    # =========================================================================
    # WebSocket Subscription
    # =========================================================================

    def subscribe(self, subscriber: WebSocketSubscriber) -> None:
        """Subscribe to spec changes."""
        if subscriber not in self._subscribers:
            self._subscribers.append(subscriber)

    def unsubscribe(self, subscriber: WebSocketSubscriber) -> None:
        """Unsubscribe from spec changes."""
        if subscriber in self._subscribers:
            self._subscribers.remove(subscriber)

    def _broadcast(self, message: Dict[str, Any]) -> None:
        """Broadcast message to all subscribers."""
        import asyncio

        for subscriber in self._subscribers:
            try:
                # Handle both sync and async contexts
                try:
                    loop = asyncio.get_running_loop()
                    loop.create_task(subscriber.send_json(message))
                except RuntimeError:
                    # No running loop, try direct call if possible
                    pass
            except Exception:
                # Subscriber may have disconnected
                pass

    # =========================================================================
    # Helper Methods
    # =========================================================================

    def _compute_hash(self, data: Dict) -> str:
        """Compute hash of spec data for conflict detection."""
        # Sort keys for consistent hashing
        json_str = json.dumps(data, sort_keys=True, ensure_ascii=False)
        return hashlib.sha256(json_str.encode()).hexdigest()[:16]

    def _generate_id(self, node_type: str, data: Dict) -> str:
        """Generate unique ID for a node type."""
        prefix_map = {
            "designVar": "dv",
            "design_variable": "dv",
            "extractor": "ext",
            "objective": "obj",
            "constraint": "con"
        }
        prefix = prefix_map.get(node_type, node_type[:3])

        # Find existing IDs
        section = self._get_section_for_type(node_type)
        existing_ids: Set[str] = set()
        if section in data and data[section]:
            existing_ids = {n.get("id", "") for n in data[section]}

        # Generate next available ID
        for i in range(1, 1000):
            new_id = f"{prefix}_{i:03d}"
            if new_id not in existing_ids:
                return new_id

        raise SpecManagerError(f"Cannot generate ID for {node_type}: too many nodes")

    def _get_section_for_type(self, node_type: str) -> str:
        """Map node type to spec section name."""
        section_map = {
            "designVar": "design_variables",
            "design_variable": "design_variables",
            "extractor": "extractors",
            "objective": "objectives",
            "constraint": "constraints"
        }
        return section_map.get(node_type, node_type + "s")

    def _auto_position(self, node_type: str, data: Dict) -> Dict[str, float]:
        """Calculate auto position for a new node."""
        # Default x positions by type
        x_positions = {
            "designVar": 50,
            "design_variable": 50,
            "extractor": 740,
            "objective": 1020,
            "constraint": 1020
        }

        x = x_positions.get(node_type, 400)

        # Find max y position for this type
        section = self._get_section_for_type(node_type)
        max_y = 0
        if section in data and data[section]:
            for node in data[section]:
                pos = node.get("canvas_position", {})
                y = pos.get("y", 0)
                if y > max_y:
                    max_y = y

        # Place below existing nodes
        y = max_y + 100 if max_y > 0 else 100

        return {"x": x, "y": y}


# =========================================================================
# Factory Function
# =========================================================================

def get_spec_manager(study_path: Union[str, Path]) -> SpecManager:
    """
    Get a SpecManager instance for a study.

    Args:
        study_path: Path to the study directory

    Returns:
        SpecManager instance
    """
    return SpecManager(study_path)