"""
Simulate endpoint — Manual switch control and power flow simulation.
"""
from __future__ import annotations

import json
from typing import Optional
from fastapi import APIRouter, HTTPException, Depends
from pydantic import BaseModel, Field

from src.grid.loader import load_network, clone_network, get_line_info
from src.grid.power_flow import apply_topology, run_power_flow, extract_results, check_radial_connected, check_topology_valid
from src.evaluation.metrics import compute_impact
from api.auth import optional_auth, require_auth, FirebaseUser
from api.database import log_usage, log_audit

router = APIRouter()


class SimulateRequest(BaseModel):
    system: str = Field(default="case33bw", description="IEEE test system name")
    open_lines: list[int] = Field(description="List of line indices to set as OPEN")
    load_multiplier: float = Field(default=1.0, ge=0.5, le=2.0, description="Load scaling factor")


@router.post("/simulate")
def simulate(req: SimulateRequest, user: FirebaseUser = Depends(optional_auth)):
    """Simulate power flow with custom switch configuration.
    
    Allows manual open/close of switches and recomputes losses.
    """
    try:
        net = load_network(req.system)
    except ValueError as exc:
        raise HTTPException(status_code=400, detail=str(exc))
    
    # Scale loads if multiplier != 1.0
    if req.load_multiplier != 1.0:
        net.load["p_mw"] *= req.load_multiplier
        net.load["q_mvar"] *= req.load_multiplier
    
    # Get baseline first
    net_baseline = clone_network(net)
    if not run_power_flow(net_baseline):
        raise HTTPException(status_code=500, detail="Baseline power flow did not converge")
    baseline = extract_results(net_baseline)
    
    # Check connectivity (required) — radiality is a soft warning, not a hard block
    if not check_topology_valid(net, req.open_lines, require_radial=False):
        raise HTTPException(
            status_code=400,
            detail="Invalid topology: all buses must remain connected"
        )
    
    # Apply topology and run power flow
    net_sim = apply_topology(net, req.open_lines)
    if not run_power_flow(net_sim):
        raise HTTPException(status_code=500, detail="Power flow did not converge for this configuration")
    
    simulated = extract_results(net_sim)
    simulated["open_lines"] = req.open_lines
    
    # Compute impact
    impact = compute_impact(baseline, simulated)
    
    # Log if authenticated
    if user:
        try:
            # Calculate annualized values
            hours_per_year = 8760
            saved_kw = baseline["total_loss_kw"] - simulated["total_loss_kw"]
            saved_kwh = saved_kw * hours_per_year
            co2_saved = saved_kwh * 0.50  # Egypt factor
            money_saved = saved_kwh * 0.08
            
            log_usage(
                firebase_uid=user.uid,
                system=req.system,
                method="simulate",
                baseline_loss_kw=baseline["total_loss_kw"],
                optimized_loss_kw=simulated["total_loss_kw"],
                energy_saved_kwh=saved_kwh,
                co2_saved_kg=co2_saved,
                money_saved_usd=money_saved,
                computation_time_sec=0.0,
                load_multiplier=req.load_multiplier,
                switches_changed=json.dumps(req.open_lines),
            )
        except Exception:
            pass  # Don't fail request if logging fails
    
    return {
        "system": req.system,
        "load_multiplier": req.load_multiplier,
        "baseline": baseline,
        "simulated": simulated,
        "impact": impact,
        "open_lines": req.open_lines,
    }


class ToggleSwitchRequest(BaseModel):
    system: str = Field(default="case33bw")
    line_id: int = Field(description="Line index to toggle")
    current_open_lines: list[int] = Field(description="Current list of open line indices")


@router.post("/simulate/toggle")
def toggle_switch(req: ToggleSwitchRequest, user: FirebaseUser = Depends(optional_auth)):
    """Toggle a single switch and return the new configuration validity."""
    try:
        net = load_network(req.system)
    except ValueError as exc:
        raise HTTPException(status_code=400, detail=str(exc))
    
    # Compute new open lines
    if req.line_id in req.current_open_lines:
        new_open_lines = [l for l in req.current_open_lines if l != req.line_id]
        action = "closed"
    else:
        new_open_lines = req.current_open_lines + [req.line_id]
        action = "opened"
    
    # Check connectivity (hard requirement) — loops are allowed
    is_connected = check_topology_valid(net, new_open_lines, require_radial=False)
    is_distribution = "33" in req.system
    is_radial = check_topology_valid(net, new_open_lines, require_radial=True) if is_connected else False

    result = {
        "line_id": req.line_id,
        "action": action,
        "new_open_lines": new_open_lines,
        "is_valid": is_connected,
    }

    if is_connected:
        # Run power flow — pandapower handles meshed grids fine
        net_sim = apply_topology(net, new_open_lines)
        if run_power_flow(net_sim):
            simulated = extract_results(net_sim)
            result["power_flow"] = simulated
            if is_distribution and not is_radial:
                result["warnings"] = ["Configuration has loops — distribution grids are normally operated radially."]
        else:
            result["is_valid"] = False
            result["error"] = "Power flow did not converge"
    else:
        result["error"] = "Configuration disconnects the network — all buses must remain reachable"
    
    return result