"""Virtual power supply simulator.

This module implements a SCPI-based virtual power supply that interfaces
with the physics engine to provide realistic power supply simulation.
"""

from __future__ import annotations

from typing import TYPE_CHECKING

from py_dvt_ate.instruments.scpi import SCPICommand
from py_dvt_ate.simulation.virtual.base import BaseInstrument

if TYPE_CHECKING:
    from py_dvt_ate.simulation.physics.engine import PhysicsEngine


class PowerSupplySim(BaseInstrument):
    """Virtual power supply simulator.

    Simulates a programmable DC power supply with SCPI control interface.
    The power supply provides input voltage to the DUT via the physics engine.

    SCPI Commands:
        VOLT <value>       - Set output voltage in volts
        VOLT?              - Query voltage setpoint
        CURR <value>       - Set current limit in amps
        CURR?              - Query current limit
        OUTP <ON|OFF|1|0>  - Enable/disable output
        OUTP?              - Query output state (1=on, 0=off)
        MEAS:VOLT?         - Measure actual output voltage
        MEAS:CURR?         - Measure actual output current

    Attributes:
        manufacturer: "PyDVTATE"
        model: "PS-SIM-001"
    """

    manufacturer = "PyDVTATE"
    model = "PS-SIM-001"
    serial_number = "PSSIM001"
    firmware_version = "1.0.0"

    # Default values
    DEFAULT_VOLTAGE = 0.0
    DEFAULT_CURRENT_LIMIT = 1.0

    def __init__(self, physics_engine: PhysicsEngine | None = None) -> None:
        """Initialise the power supply simulator.

        Args:
            physics_engine: Reference to physics engine for electrical state.
        """
        self._voltage_setpoint = self.DEFAULT_VOLTAGE
        self._current_limit = self.DEFAULT_CURRENT_LIMIT
        self._output_enabled = False
        super().__init__(physics_engine)

    def _setup_commands(self) -> None:
        """Register power supply SCPI commands."""
        self.register_command("VOLT", self._handle_volt)
        self.register_command("CURR", self._handle_curr)
        self.register_command("OUTP", self._handle_outp)
        self.register_command("MEAS:VOLT", self._handle_meas_volt)
        self.register_command("MEAS:CURR", self._handle_meas_curr)

    def reset(self) -> None:
        """Reset power supply to default state."""
        self._voltage_setpoint = self.DEFAULT_VOLTAGE
        self._current_limit = self.DEFAULT_CURRENT_LIMIT
        self._output_enabled = False

        if self._physics_engine is not None:
            self._physics_engine.set_input_voltage(0.0)
            self._physics_engine.set_output_enabled(False)

    def _handle_volt(self, command: SCPICommand) -> str:
        """Handle VOLT command/query.

        Args:
            command: Parsed SCPI command.

        Returns:
            Voltage setpoint for query, empty string for set command.

        Raises:
            ValueError: If voltage argument is invalid.
        """
        if command.is_query:
            return f"{self._voltage_setpoint:.3f}"

        if not command.arguments:
            raise ValueError("VOLT requires a value")

        try:
            voltage = float(command.arguments[0])
        except ValueError as err:
            raise ValueError(f"Invalid voltage value: {command.arguments[0]}") from err

        if voltage < 0:
            raise ValueError("Voltage cannot be negative")

        self._voltage_setpoint = voltage

        if self._physics_engine is not None and self._output_enabled:
            self._physics_engine.set_input_voltage(voltage)

        return ""

    def _handle_curr(self, command: SCPICommand) -> str:
        """Handle CURR command/query.

        Args:
            command: Parsed SCPI command.

        Returns:
            Current limit for query, empty string for set command.

        Raises:
            ValueError: If current argument is invalid.
        """
        if command.is_query:
            return f"{self._current_limit:.3f}"

        if not command.arguments:
            raise ValueError("CURR requires a value")

        try:
            current = float(command.arguments[0])
        except ValueError as err:
            raise ValueError(f"Invalid current value: {command.arguments[0]}") from err

        if current < 0:
            raise ValueError("Current limit cannot be negative")

        self._current_limit = current
        return ""

    def _handle_outp(self, command: SCPICommand) -> str:
        """Handle OUTP command/query.

        Args:
            command: Parsed SCPI command.

        Returns:
            "1" or "0" for query, empty string for set command.

        Raises:
            ValueError: If output argument is invalid.
        """
        if command.is_query:
            return "1" if self._output_enabled else "0"

        if not command.arguments:
            raise ValueError("OUTP requires a value (ON, OFF, 1, or 0)")

        arg = command.arguments[0].upper()
        if arg in ("ON", "1"):
            self._output_enabled = True
        elif arg in ("OFF", "0"):
            self._output_enabled = False
        else:
            raise ValueError(f"Invalid output state: {command.arguments[0]}")

        if self._physics_engine is not None:
            self._physics_engine.set_output_enabled(self._output_enabled)
            if self._output_enabled:
                self._physics_engine.set_input_voltage(self._voltage_setpoint)
            else:
                self._physics_engine.set_input_voltage(0.0)

        return ""

    def _handle_meas_volt(self, command: SCPICommand) -> str:
        """Handle MEAS:VOLT? query.

        Args:
            command: Parsed SCPI command.

        Returns:
            Measured output voltage.

        Raises:
            ValueError: If used as command (not query).
        """
        if not command.is_query:
            raise ValueError("MEAS:VOLT is query only")

        if not self._output_enabled:
            return "0.000"

        if self._physics_engine is None:
            return f"{self._voltage_setpoint:.3f}"

        electrical_state = self._physics_engine.get_electrical_state()
        return f"{electrical_state.input_voltage:.3f}"

    def _handle_meas_curr(self, command: SCPICommand) -> str:
        """Handle MEAS:CURR? query.

        Args:
            command: Parsed SCPI command.

        Returns:
            Measured output current.

        Raises:
            ValueError: If used as command (not query).
        """
        if not command.is_query:
            raise ValueError("MEAS:CURR is query only")

        if not self._output_enabled:
            return "0.000"

        if self._physics_engine is None:
            return "0.000"

        electrical_state = self._physics_engine.get_electrical_state()
        # Total current is load current + quiescent current
        total_current = electrical_state.load_current + electrical_state.quiescent_current
        return f"{total_current:.3f}"