"""
Policy Impact Simulator API endpoints
Provides REST API access to policy simulation functionality
"""

from fastapi import APIRouter, HTTPException, Query
from pydantic import BaseModel, Field
from typing import List, Optional, Dict, Any
from datetime import datetime, date
from enum import Enum

from policy_impact_simulator import (
    PolicyImpactSimulator, 
    PolicyScenario, 
    PolicyParameter,
    create_sample_scenarios
)

router = APIRouter(prefix="/api/policy-simulator", tags=["policy-simulator"])

# Pydantic models for API
class PolicyParameterEnum(str, Enum):
    pension_factor = "pension_factor"
    dearness_relief = "dearness_relief"
    basic_pension = "basic_pension"
    minimum_pension = "minimum_pension"
    commutation_factor = "commutation_factor"
    medical_allowance = "medical_allowance"
    family_pension = "family_pension"
    gratuity_limit = "gratuity_limit"
    hra_percentage = "hra_percentage"
    retirement_age = "retirement_age"

class PolicySimulationRequest(BaseModel):
    parameter: PolicyParameterEnum = Field(..., description="Policy parameter to simulate")
    current_value: float = Field(..., description="Current value of the parameter")
    proposed_value: float = Field(..., description="Proposed new value")
    effective_date: date = Field(..., description="When the policy change takes effect")
    affected_population: int = Field(..., description="Number of people affected")
    annual_growth_rate: float = Field(0.03, description="Annual population growth rate")
    inflation_rate: float = Field(0.06, description="Expected inflation rate")
    projection_years: int = Field(5, description="Number of years to project", ge=1, le=10)
    include_variants: bool = Field(True, description="Include best/worst case scenarios")

class QuickSimulationRequest(BaseModel):
    scenario_name: str = Field(..., description="Name of predefined scenario")
    years: int = Field(5, description="Projection years", ge=1, le=10)

# Initialize simulator
simulator = PolicyImpactSimulator()

@router.post("/simulate")
async def simulate_policy_impact(request: PolicySimulationRequest):
    """
    Simulate the impact of a policy change
    
    Provides comprehensive analysis including:
    - Baseline vs scenario projections
    - Best/base/worst case scenarios
    - Clause analysis and timeline
    - Exportable evidence pack
    """
    try:
        # Convert API request to internal scenario
        scenario = PolicyScenario(
            parameter=PolicyParameter(request.parameter.value),
            current_value=request.current_value,
            proposed_value=request.proposed_value,
            effective_date=datetime.combine(request.effective_date, datetime.min.time()),
            affected_population=request.affected_population,
            annual_growth_rate=request.annual_growth_rate,
            inflation_rate=request.inflation_rate
        )
        
        # Run simulation
        result = simulator.simulate_policy_impact(
            scenario=scenario,
            years=request.projection_years,
            include_variants=request.include_variants
        )
        
        if "error" in result:
            raise HTTPException(status_code=500, detail=result["error"])
        
        return {
            "success": True,
            "simulation_result": result,
            "api_version": "1.0",
            "generated_at": datetime.now().isoformat()
        }
        
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Simulation failed: {str(e)}")

@router.post("/quick-simulate")
async def quick_simulate(request: QuickSimulationRequest):
    """
    Run a quick simulation using predefined scenarios
    
    Available scenarios:
    - dr_increase_6_percent: Increase DR from 12% to 18%
    - basic_pension_boost: Increase basic pension from ₹6000 to ₹8000
    - medical_allowance_double: Double medical allowance to ₹2000
    """
    try:
        predefined_scenarios = {
            "dr_increase_6_percent": PolicyScenario(
                parameter=PolicyParameter.DEARNESS_RELIEF,
                current_value=12.0,
                proposed_value=18.0,
                effective_date=datetime(2025, 4, 1),
                affected_population=510000
            ),
            "basic_pension_boost": PolicyScenario(
                parameter=PolicyParameter.BASIC_PENSION,
                current_value=6000,
                proposed_value=8000,
                effective_date=datetime(2025, 7, 1),
                affected_population=450000
            ),
            "medical_allowance_double": PolicyScenario(
                parameter=PolicyParameter.MEDICAL_ALLOWANCE,
                current_value=1000,
                proposed_value=2000,
                effective_date=datetime(2025, 10, 1),
                affected_population=510000
            )
        }
        
        if request.scenario_name not in predefined_scenarios:
            raise HTTPException(
                status_code=400, 
                detail=f"Unknown scenario. Available: {list(predefined_scenarios.keys())}"
            )
        
        scenario = predefined_scenarios[request.scenario_name]
        result = simulator.simulate_policy_impact(scenario, request.years, True)
        
        return {
            "success": True,
            "scenario_name": request.scenario_name,
            "simulation_result": result
        }
        
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

@router.get("/parameters")
async def get_policy_parameters():
    """Get available policy parameters with their definitions"""
    try:
        parameters = {}
        for param in PolicyParameter:
            param_def = simulator.policy_definitions.get(param, {})
            parameters[param.value] = {
                "name": param_def.get("name", param.value),
                "description": param_def.get("description", ""),
                "unit": param_def.get("unit", ""),
                "typical_range": param_def.get("typical_range", (0, 100)),
                "current_rajasthan": param_def.get("current_rajasthan", 0),
                "impact_type": param_def.get("impact_type", "benefit")
            }
        
        return {
            "success": True,
            "parameters": parameters,
            "total_count": len(parameters)
        }
        
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

@router.get("/scenarios/samples")
async def get_sample_scenarios():
    """Get sample scenarios for testing and demonstration"""
    try:
        samples = create_sample_scenarios()
        
        scenarios_data = []
        for i, scenario in enumerate(samples):
            scenarios_data.append({
                "id": f"sample_{i+1}",
                "parameter": scenario.parameter.value,
                "parameter_name": simulator.policy_definitions[scenario.parameter]["name"],
                "current_value": scenario.current_value,
                "proposed_value": scenario.proposed_value,
                "effective_date": scenario.effective_date.date().isoformat(),
                "affected_population": scenario.affected_population,
                "description": f"Sample scenario: {simulator.policy_definitions[scenario.parameter]['name']} change"
            })
        
        return {
            "success": True,
            "sample_scenarios": scenarios_data,
            "usage": "Use these scenarios with /quick-simulate endpoint"
        }
        
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

@router.get("/analysis/{simulation_id}")
async def get_detailed_analysis(simulation_id: str):
    """Get detailed analysis for a completed simulation"""
    # This would typically fetch from a database
    # For now, return a placeholder response
    return {
        "success": True,
        "message": "Detailed analysis endpoint - would fetch stored simulation results",
        "simulation_id": simulation_id,
        "note": "In production, this would retrieve complete analysis from database"
    }

@router.post("/compare")
async def compare_scenarios(scenarios: List[PolicySimulationRequest]):
    """Compare multiple policy scenarios side by side"""
    try:
        if len(scenarios) > 5:
            raise HTTPException(status_code=400, detail="Maximum 5 scenarios can be compared")
        
        comparison_results = []
        
        for i, request in enumerate(scenarios):
            scenario = PolicyScenario(
                parameter=PolicyParameter(request.parameter.value),
                current_value=request.current_value,
                proposed_value=request.proposed_value,
                effective_date=datetime.combine(request.effective_date, datetime.min.time()),
                affected_population=request.affected_population,
                annual_growth_rate=request.annual_growth_rate,
                inflation_rate=request.inflation_rate
            )
            
            result = simulator.simulate_policy_impact(scenario, request.projection_years, False)
            comparison_results.append({
                "scenario_index": i + 1,
                "parameter": request.parameter.value,
                "impact_summary": result.get("total_impact", {}),
                "first_year_impact": result["scenario_projections"][0].impact if result.get("scenario_projections") else 0
            })
        
        # Create comparison summary
        total_impacts = [r.get("impact_summary", {}).get("total_additional_cost_crores", 0) for r in comparison_results]
        
        return {
            "success": True,
            "comparison_count": len(scenarios),
            "scenarios": comparison_results,
            "summary": {
                "highest_impact": max(total_impacts) if total_impacts else 0,
                "lowest_impact": min(total_impacts) if total_impacts else 0,
                "total_combined_impact": sum(total_impacts),
                "recommendation": "Detailed comparison analysis completed"
            }
        }
        
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

@router.get("/export/{simulation_id}")
async def export_simulation_data(
    simulation_id: str,
    format: str = Query("json", regex="^(json|csv|pdf)$")
):
    """Export simulation results in various formats"""
    try:
        # This would typically fetch the simulation from database
        # For now, return export information
        
        export_info = {
            "json": "Complete simulation data in JSON format",
            "csv": "Yearly projections and impact data in CSV format",
            "pdf": "Formatted policy impact report in PDF format"
        }
        
        return {
            "success": True,
            "simulation_id": simulation_id,
            "export_format": format,
            "description": export_info.get(format, "Unknown format"),
            "download_url": f"/api/policy-simulator/download/{simulation_id}/{format}",
            "note": "In production, would generate actual downloadable files"
        }
        
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))