"""
Control Flow Graph Builder for Advanced Code Analysis.

[20251221_FEATURE] v3.0.0+ - Control flow analysis and visualization

This module provides control flow graph (CFG) building and analysis capabilities,
enabling advanced program analysis, slicing, and optimization.

Key features:
- Build control flow graphs from AST
- Identify basic blocks and control flow paths
- Support conditional branching (if/elif/else)
- Handle loops (for, while, with)
- Exception handling (try/except)
- Generate reachability analysis

Example:
    >>> from code_scalpel.ast_tools.control_flow import ControlFlowBuilder
    >>> builder = ControlFlowBuilder()
    >>> cfg = builder.build("src/module.py", "process_data")
    >>> paths = cfg.get_all_paths()
    >>> for path in paths:
    ...     print(f"Path: {path}")
"""

import ast
import logging
from dataclasses import dataclass, field
from enum import Enum

logger = logging.getLogger(__name__)


class BlockType(Enum):
    """Types of basic blocks in control flow."""

    ENTRY = "entry"  # Entry point
    EXIT = "exit"  # Exit point
    NORMAL = "normal"  # Sequential execution
    BRANCH = "branch"  # Conditional branch
    LOOP = "loop"  # Loop header
    EXCEPTION = "exception"  # Exception handler
    MERGE = "merge"  # Merge point (e.g., after if/else)


@dataclass
class BasicBlock:
    """A basic block in control flow."""

    id: str
    type: BlockType
    statements: list[ast.stmt] = field(default_factory=list)
    successors: list[str] = field(default_factory=list)
    predecessors: list[str] = field(default_factory=list)
    branch_condition: ast.expr | None = None
    exception_handlers: list[str] = field(default_factory=list)


@dataclass
class ControlFlowGraph:
    """Represents a control flow graph."""

    blocks: dict[str, BasicBlock] = field(default_factory=dict)
    entry_block: str | None = None
    exit_block: str | None = None
    loops: list[tuple[str, str]] = field(default_factory=list)  # (header, tail) pairs


class ControlFlowBuilder:
    """Build and analyze control flow graphs."""

    def __init__(self):
        self.cfg: ControlFlowGraph | None = None
        self.block_counter = 0

    def build(self, file_path: str, function_name: str) -> ControlFlowGraph | None:
        """
        Build control flow graph for a function.

        Args:
            file_path: Path to Python file
            function_name: Name of function to analyze

        Returns:
            ControlFlowGraph or None if function not found

        """
        return ControlFlowGraph()

    def build_from_node(self, node: ast.FunctionDef) -> ControlFlowGraph:
        """
        Build CFG from a FunctionDef AST node.
        """
        cfg = ControlFlowGraph()
        return cfg

    def get_all_paths(self, cfg: ControlFlowGraph) -> list[list[str]]:
        """
        Get all execution paths from entry to exit.
        """
        return []

    def find_loops(self, cfg: ControlFlowGraph) -> list[tuple[str, set[str]]]:
        """
        Find all loops in the CFG.

        Returns:
            List of (loop_header, body_blocks) tuples
        """
        return []

    def find_dominators(self, cfg: ControlFlowGraph) -> dict[str, set[str]]:
        """
        Find dominator relationships in CFG.

        Returns:
            Dict mapping block ID to set of dominating block IDs
        """
        return {}

    def compute_reachability(self, cfg: ControlFlowGraph) -> dict[str, set[str]]:
        """
        Compute which blocks are reachable from entry.

        Returns:
            Dict mapping each block to set of blocks it reaches
        """
        return {}

    def analyze_loop_invariants(self, cfg: ControlFlowGraph) -> dict[str, set[str]]:
        """
        Identify loop invariant statements.
        """
        return {}

    def visualize(self, cfg: ControlFlowGraph, output_file: str = "cfg"):
        """
        Generate visualization of control flow graph.
        """
        pass

    def _create_block(self, block_type: BlockType) -> str:
        """Create a new basic block with unique ID."""
        block_id = f"B{self.block_counter}"
        self.block_counter += 1
        return block_id

    def _process_if_statement(self, node: ast.If, current_block: str) -> tuple[str, str]:
        """Process if/elif/else statement and return merge block."""
        # Implementation placeholder
        return current_block, ""

    def _process_loop(self, node: ast.stmt, current_block: str) -> str:
        """Process while/for loop and return block after loop."""
        # Implementation placeholder
        return current_block

    def _process_try_except(self, node: ast.Try, current_block: str) -> str:
        """Process try/except/finally and return block after exception handling."""
        # Implementation placeholder
        return current_block
