#!/usr/bin/env python3
"""
Radon Parser - Code Complexity and Metrics.
============================================

Radon is a Python tool for measuring code complexity metrics including
Cyclomatic Complexity (CC), Cognitive Complexity, and Maintainability Index.
This module provides structured parsing of Radon output and metrics.

Implementation Status: NOT IMPLEMENTED
Priority: P2 - HIGH

============================================================================
============================================================================
COMMUNITY TIER - Core Complexity Metrics (P0-P2) [NOT IMPLEMENTED]
============================================================================

[P0_CRITICAL] Basic Complexity Analysis:
    - Parse Radon CC (Cyclomatic Complexity) output
    - Parse Radon MI (Maintainability Index) output
    - Function-level complexity metrics
    - Class-level complexity aggregation
    - Complexity grade classification (A-F)
    - Test count: 45 tests

[P1_HIGH] Advanced Metrics:
    - Cognitive complexity calculation
    - Halstead metrics integration
    - Nesting depth tracking
    - Parameter complexity
    - Test count: 40 tests

[P2_MEDIUM] Complexity Reporting:
    - Per-file complexity summary
    - High-complexity item identification
    - Complexity trend visualization
    - Risk level categorization
    - Test count: 35 tests

[P2_MEDIUM] Configuration and Thresholds:
    - Configurable complexity thresholds
    - Per-project grade standards
    - Custom metric calculations
    - Test count: 25 tests

============================================================================
PRO TIER - Advanced Complexity Analysis (P1-P3)
============================================================================

[P1_HIGH] Detailed Metrics:
    - Lines of Code (LOC) breakdown
    - Logical LOC calculation
    - Comment density analysis
    - Blank line ratio
    - Test count: 40 tests

[P1_HIGH] Code Quality Indicators:
    - Maintainability Index components
    - Code smell correlation
    - Refactoring priority scoring
    - Test count: 45 tests

[P2_MEDIUM] Comparative Analysis:
    - Complexity trends over time
    - Peer comparison (similar projects)
    - Industry benchmark comparison
    - Test count: 35 tests

[P3_LOW] Advanced Reporting:
    - Complexity heat maps
    - Interactive complexity dashboards
    - Complexity distribution charts
    - Test count: 30 tests

============================================================================
ENTERPRISE TIER - Enterprise Complexity Management (P2-P4)
============================================================================

[P2_MEDIUM] Project-Wide Analysis:
    - Multi-module complexity aggregation
    - Package-level complexity metrics
    - Dependency complexity impact
    - Test count: 50 tests

[P2_MEDIUM] Quality Gates:
    - Complexity-based CI/CD gates
    - Automated complexity enforcement
    - Complexity SLA tracking
    - Test count: 40 tests

[P3_LOW] Strategic Metrics:
    - Technical debt quantification
    - Refactoring ROI estimation
    - Complexity reduction planning
    - Test count: 35 tests

[P4_LOW] ML-Driven Insights:
    - Complexity prediction models
    - Automated refactoring suggestions
    - Risk assessment algorithms
    - Test count: 30 tests

============================================================================
TOTAL TEST ESTIMATE: 450 tests (145 COMMUNITY + 150 PRO + 155 ENTERPRISE)
============================================================================

==============================================================================
PLANNED [P2-RADON-001]: RadonParser for complexity metrics
==============================================================================
Priority: HIGH
Status: ⏳ NOT IMPLEMENTED

Planned Features:
    - [ ] Parse Cyclomatic Complexity (CC) metrics
    - [ ] Parse Maintainability Index (MI) metrics
    - [ ] Parse Cognitive Complexity metrics
    - [ ] Rank complexity by severity (A, B, C, D, E, F)
    - [ ] Analyze function/class-level metrics
    - [ ] Support JSON output format
    - [ ] Track complexity trends across versions

Complexity Metrics:
    - Cyclomatic Complexity (CC): Number of decision points
    - Cognitive Complexity: Mental effort to understand code
    - Maintainability Index (MI): Overall code quality (0-100)

Complexity Grades:
    - A: 1-5 (Simple, Low Risk)
    - B: 6-10 (Moderate, Low Risk)
    - C: 11-20 (Complex, Medium Risk)
    - D: 21-30 (Very Complex, High Risk)
    - E: 31-40 (Extremely Complex, Very High Risk)
    - F: >40 (Unmaintainable, Extreme Risk)

    Radon produces JSON with metrics per function/class:
    ```json
    {
        "example.py": {
            "MyClass": {
                "type": "class",
                "complexity": 3,
                "lineno": 1,
                "col_offset": 0,
                "endline": 20,
                "classname": "MyClass",
                "methods": {
                    "method_name": {
                        "type": "method",
                        "complexity": 2,
                        "lineno": 5,
                        "col_offset": 4
                    }
                }
            },
            "function_name": {
                "type": "function",
                "complexity": 4,
                "lineno": 25,
                "col_offset": 0
            }
        }
    }
    ```

Data Structures (Planned):
    ```python
    @dataclass
    class ComplexityMetrics:
        cyclomatic_complexity: int
        cognitive_complexity: int | None
        maintainability_index: float | None
        grade: str  # A-F
        is_complex: bool  # True if C grade or higher

    @dataclass
    class FunctionComplexity:
        name: str
        location: SourceLocation
        metrics: ComplexityMetrics
        affected_lines: int

    @dataclass
    class ClassComplexity:
        name: str
        location: SourceLocation
        metrics: ComplexityMetrics
        methods: list[FunctionComplexity]

    @dataclass
    class RadonReport:
        file_path: str
        overall_mi: float | None  # Maintainability Index for file
        functions: list[FunctionComplexity]
        classes: list[ClassComplexity]
        high_complexity_items: list[str]  # Names of D/E/F items
        average_complexity: float
    ```

Test Cases (Planned):
    - Parse cyclomatic complexity metrics
    - Verify complexity grading
    - Identify high-complexity functions
    - Test maintainability index calculation
    - Verify class metrics aggregation

Related Features:
    - Complements CodeQualityParser
    - Works with AST parser for structure analysis
    - Useful for refactoring identification
    - Important for code review and quality gates

Notes for Implementation:
    - Cyclomatic Complexity counts decision points
    - Cognitive Complexity adds weights for nesting
    - Maintainability Index combines metrics
    - Useful for identifying refactoring candidates
    - Can set thresholds for CI/CD gates

API Design (Planned):
    ```python
    class RadonParser:
        def __init__(self, min_cc: int = 5):
            self.min_cc = min_cc

        def analyze_file(self, path: str) -> RadonReport:
            '''Analyze complexity metrics in a file.'''
            pass

        def analyze_code(self, code: str, filename: str = "<string>") -> RadonReport:
            '''Analyze complexity metrics in code string.'''
            pass

        def get_grade(self, complexity: int) -> str:
            '''Get letter grade (A-F) for complexity.'''
            pass

        def is_complex(self, complexity: int) -> bool:
            '''Check if complexity exceeds threshold.'''
            pass
    ```
"""

from __future__ import annotations

from dataclasses import dataclass, field
from pathlib import Path


@dataclass
class SourceLocation:
    """Location in source code."""

    line: int
    column: int = 0
    end_line: int | None = None
    end_column: int | None = None


@dataclass
class ComplexityMetrics:
    """Code complexity metrics for a function or class."""

    cyclomatic_complexity: int
    cognitive_complexity: int | None = None
    maintainability_index: float | None = None

    @property
    def grade(self) -> str:
        """Get letter grade (A-F) based on cyclomatic complexity."""
        if self.cyclomatic_complexity <= 5:
            return "A"
        elif self.cyclomatic_complexity <= 10:
            return "B"
        elif self.cyclomatic_complexity <= 20:
            return "C"
        elif self.cyclomatic_complexity <= 30:
            return "D"
        elif self.cyclomatic_complexity <= 40:
            return "E"
        else:
            return "F"

    @property
    def is_complex(self) -> bool:
        """Check if complexity is concerning (grade C or worse)."""
        return self.cyclomatic_complexity > 10


@dataclass
class FunctionComplexity:
    """Complexity metrics for a function."""

    name: str
    location: SourceLocation
    metrics: ComplexityMetrics
    affected_lines: int = 0


@dataclass
class ClassComplexity:
    """Complexity metrics for a class."""

    name: str
    location: SourceLocation
    metrics: ComplexityMetrics
    methods: list[FunctionComplexity] = field(default_factory=list)

    def get_average_method_complexity(self) -> float:
        """Calculate average complexity of methods."""
        if not self.methods:
            return 0.0
        return sum(m.metrics.cyclomatic_complexity for m in self.methods) / len(self.methods)


@dataclass
class RadonConfig:
    """Configuration for Radon parser."""

    min_complexity: int = 5  # Flag functions with complexity >= this
    show_json: bool = True
    exclude_patterns: list[str] = field(default_factory=list)

    @classmethod
    def from_pyproject(cls, pyproject_path: str | Path) -> RadonConfig:
        """Load configuration from pyproject.toml."""
        return cls()


@dataclass
class RadonReport:
    """Results from Radon complexity analysis."""

    file_path: str
    overall_mi: float | None = None  # Maintainability Index for entire file
    functions: list[FunctionComplexity] = field(default_factory=list)
    classes: list[ClassComplexity] = field(default_factory=list)
    error: str | None = None

    @property
    def high_complexity_functions(self) -> list[FunctionComplexity]:
        """Get functions with concerning complexity (grade C or worse)."""
        return [f for f in self.functions if f.metrics.is_complex]

    @property
    def high_complexity_classes(self) -> list[ClassComplexity]:
        """Get classes with concerning complexity (grade C or worse)."""
        return [c for c in self.classes if c.metrics.is_complex]

    @property
    def average_complexity(self) -> float:
        """Calculate average complexity across all functions."""
        all_items = list(self.functions)
        for cls in self.classes:
            all_items.extend(cls.methods)

        if not all_items:
            return 0.0
        return sum(item.metrics.cyclomatic_complexity for item in all_items) / len(all_items)


class RadonParser:
    """
    Parser for code complexity metrics using Radon.

    STATUS: NOT IMPLEMENTED
    PRIORITY: P2 - HIGH

    Features (Planned):
        - Cyclomatic Complexity (CC) analysis
        - Cognitive Complexity analysis
        - Maintainability Index (MI) calculation
        - Complexity grading (A-F)
        - Function and class metrics
        - Configuration support

        - Implement analyze_file() method
        - Implement analyze_code() method
        - Add JSON parsing
        - Implement grade calculation
        - Add configuration support
    """

    # Complexity grade thresholds
    GRADE_THRESHOLDS = {
        "A": (1, 5),
        "B": (6, 10),
        "C": (11, 20),
        "D": (21, 30),
        "E": (31, 40),
        "F": (41, float("inf")),
    }

    def __init__(self, config: RadonConfig | None = None):
        """
        Initialize Radon parser.

        Args:
            config: RadonConfig instance or None to use defaults
        """
        self.config = config or RadonConfig()

    def analyze_file(self, file_path: str | Path) -> RadonReport:
        """
        Analyze code complexity in a Python file.

        Args:
            file_path: Path to Python file

        Returns:
            RadonReport with complexity metrics

        """
        raise NotImplementedError("RadonParser.analyze_file() not yet implemented")

    def analyze_code(self, code: str, filename: str = "<string>") -> RadonReport:
        """
        Analyze code complexity in Python code string.

        Args:
            code: Python source code
            filename: Filename for error reporting

        Returns:
            RadonReport with complexity metrics

        """
        raise NotImplementedError("RadonParser.analyze_code() not yet implemented")

    def get_grade(self, complexity: int) -> str:
        """
        Get letter grade (A-F) for cyclomatic complexity.

        Args:
            complexity: Cyclomatic complexity value

        Returns:
            Grade letter: A (simple) to F (unmaintainable)
        """
        for grade, (low, high) in self.GRADE_THRESHOLDS.items():
            if low <= complexity <= high:
                return grade
        return "F"
