"""Interactive CLI REPL for the OR1 Monitor using cmd.Cmd.

Provides a command-line interface for interactive simulation control,
with commands for loading programs, stepping/running simulation,
injecting tokens, and inspecting state.
"""

from __future__ import annotations

import cmd
import sys
from io import StringIO
from pathlib import Path

from cm_inst import MemOp
from monitor.backend import SimulationBackend
from monitor.commands import (
    ErrorResult,
    GraphLoaded,
    InjectCmd,
    LoadCmd,
    ResetCmd,
    RunUntilCmd,
    SendCmd,
    StepEventCmd,
    StepResult,
    StepTickCmd,
)
from monitor.formatting import (
    format_event,
    format_pe_state,
    format_sm_state,
    format_snapshot_summary,
    format_step_result,
)
from tokens import MonadToken, SMToken


class MonitorREPL(cmd.Cmd):
    """Interactive REPL for simulation control.

    Subclasses cmd.Cmd to provide a user-friendly interface to the
    SimulationBackend. Holds reference to backend and maintains
    event history and state snapshots.

    Attributes:
        backend: SimulationBackend instance
        _event_history: List of all SimEvents received so far
        _loaded: True if a simulation is currently loaded
        _last_snapshot: Most recent StateSnapshot (from load or step)
        _last_sim_time: Current simulation time
    """

    intro = "OR1 Monitor. Type 'help' for commands."
    prompt = "or1> "

    def __init__(self, backend: SimulationBackend, **kwargs):
        super().__init__(**kwargs)
        self.backend = backend
        self._event_history: list = []
        self._loaded = False
        self._last_snapshot = None
        self._last_sim_time = 0.0

    def _check_loaded(self) -> bool:
        """Check if simulation is loaded, print error if not.

        Returns:
            True if loaded, False otherwise
        """
        if not self._loaded:
            print("No simulation loaded. Use 'load <path>' first.", file=self.stdout)
            return False
        return True

    def do_load(self, arg: str) -> None:
        """Load a dfasm program: load <path>

        Reads the specified file and assembles it into a fresh simulation.
        On success, sets _loaded=True and displays initial state.
        On error, displays error messages.

        Args:
            arg: Path to .dfasm file
        """
        if not arg:
            print("Usage: load <path>", file=self.stdout)
            return

        path = Path(arg)
        if not path.exists():
            print(f"Error: file not found: {path}", file=self.stdout)
            return

        try:
            source = path.read_text()
        except Exception as e:
            print(f"Error reading file: {e}", file=self.stdout)
            return

        try:
            result = self.backend.send_command(LoadCmd(source=source))
        except Exception as e:
            print(f"Error sending command: {e}", file=self.stdout)
            return

        if isinstance(result, ErrorResult):
            print(f"Error loading program: {result.message}", file=self.stdout)
            if result.errors:
                for err in result.errors:
                    print(f"  {err}", file=self.stdout)
            return

        if isinstance(result, GraphLoaded):
            self._loaded = True
            self._last_snapshot = result.snapshot
            self._last_sim_time = result.snapshot.sim_time
            self._event_history.clear()
            print(f"Loaded {path}", file=self.stdout)
            print("", file=self.stdout)
            # Print initial state summary
            print(format_snapshot_summary(result.snapshot), file=self.stdout)

    def do_step(self, arg: str) -> None:
        """Step by one tick (all events at current time): step

        Processes all events at the current simulation time and returns.

        Args:
            arg: Unused (for cmd.Cmd compatibility)
        """
        if not self._check_loaded():
            return

        try:
            result = self.backend.send_command(StepTickCmd())
        except Exception as e:
            print(f"Error: {e}", file=self.stdout)
            return

        if isinstance(result, StepResult):
            self._event_history.extend(result.events)
            if result.snapshot:
                self._last_snapshot = result.snapshot
                self._last_sim_time = result.snapshot.sim_time
            print(format_step_result(result), file=self.stdout)

    def do_stepe(self, arg: str) -> None:
        """Step by one event: stepe

        Processes exactly one event and returns.

        Args:
            arg: Unused (for cmd.Cmd compatibility)
        """
        if not self._check_loaded():
            return

        try:
            result = self.backend.send_command(StepEventCmd())
        except Exception as e:
            print(f"Error: {e}", file=self.stdout)
            return

        if isinstance(result, StepResult):
            self._event_history.extend(result.events)
            if result.snapshot:
                self._last_snapshot = result.snapshot
                self._last_sim_time = result.snapshot.sim_time
            print(format_step_result(result), file=self.stdout)

    def do_run(self, arg: str) -> None:
        """Run until target time: run <until>

        Runs the simulation continuously until reaching the specified
        simulation time, batching events per tick.

        Args:
            arg: Target simulation time (float)
        """
        if not self._check_loaded():
            return

        if not arg:
            print("Usage: run <until>", file=self.stdout)
            return

        try:
            until = float(arg)
        except ValueError:
            print(f"Invalid time: {arg}", file=self.stdout)
            return

        try:
            result = self.backend.send_command(RunUntilCmd(until=until))
        except Exception as e:
            print(f"Error: {e}", file=self.stdout)
            return

        if isinstance(result, StepResult):
            self._event_history.extend(result.events)
            if result.snapshot:
                self._last_snapshot = result.snapshot
                self._last_sim_time = result.snapshot.sim_time

            # Print summary with event count
            event_count = len(result.events)
            print(f"Ran {event_count} events", file=self.stdout)
            print(format_step_result(result), file=self.stdout)

    def do_send(self, arg: str) -> None:
        """Send token to target: send <target> <offset> <act_id> <data> [--sm <addr> <op>]

        For MonadToken: send <target> <offset> <act_id> <data>
        For SMToken: send <target> --sm <addr> <op> [<data>]

        The --sm flag switches to SMToken mode. op is parsed from MemOp names (READ, WRITE, etc).

        Args:
            arg: Command arguments as described above
        """
        if not self._check_loaded():
            return

        if not arg:
            print("Usage: send <target> <offset> <act_id> <data> [--sm <addr> <op>]", file=self.stdout)
            return

        try:
            token = self._parse_token_args(arg)
        except ValueError as e:
            print(f"Error parsing token: {e}", file=self.stdout)
            return

        try:
            result = self.backend.send_command(SendCmd(token=token))
        except Exception as e:
            print(f"Error: {e}", file=self.stdout)
            return

        if isinstance(result, StepResult):
            self._event_history.extend(result.events)
            if result.snapshot:
                self._last_snapshot = result.snapshot
                self._last_sim_time = result.snapshot.sim_time
            print(f"Sent {token}", file=self.stdout)

    def do_inject(self, arg: str) -> None:
        """Inject token directly (no backpressure): inject <target> <offset> <act_id> <data> [--sm <addr> <op>]

        For MonadToken: inject <target> <offset> <act_id> <data>
        For SMToken: inject <target> --sm <addr> <op> [<data>]

        The --sm flag switches to SMToken mode. op is parsed from MemOp names (READ, WRITE, etc).

        Args:
            arg: Command arguments as described above
        """
        if not self._check_loaded():
            return

        if not arg:
            print("Usage: inject <target> <offset> <act_id> <data> [--sm <addr> <op>]", file=self.stdout)
            return

        try:
            token = self._parse_token_args(arg)
        except ValueError as e:
            print(f"Error parsing token: {e}", file=self.stdout)
            return

        try:
            result = self.backend.send_command(InjectCmd(token=token))
        except Exception as e:
            print(f"Error: {e}", file=self.stdout)
            return

        if isinstance(result, StepResult):
            self._event_history.extend(result.events)
            if result.snapshot:
                self._last_snapshot = result.snapshot
                self._last_sim_time = result.snapshot.sim_time
            print(f"Injected {token}", file=self.stdout)

    def _parse_token_args(self, arg: str) -> MonadToken | SMToken:
        """Parse token arguments from command line.

        Supports two modes:
        - MonadToken: <target> <offset> <act_id> <data> [--sm ...]
        - SMToken: <target> --sm <addr> <op> [<data>]

        Args:
            arg: Command arguments string

        Returns:
            Constructed token (MonadToken or SMToken)

        Raises:
            ValueError: If parsing fails
        """
        parts = arg.split()
        if not parts:
            raise ValueError("Expected at least target")

        target = int(parts[0])

        # Check for --sm flag
        if "--sm" in parts:
            sm_idx = parts.index("--sm")
            if sm_idx + 2 >= len(parts):
                raise ValueError("--sm requires <addr> <op> [<data>]")

            addr = int(parts[sm_idx + 1])
            op_name = parts[sm_idx + 2].upper()

            # Parse MemOp by name
            try:
                op = MemOp[op_name]
            except KeyError:
                raise ValueError(f"Unknown MemOp: {op_name}")

            # Optional data
            data = None
            if sm_idx + 3 < len(parts):
                data = int(parts[sm_idx + 3])

            return SMToken(target=target, addr=addr, op=op, flags=None, data=data, ret=None)
        else:
            # MonadToken mode
            if len(parts) < 4:
                raise ValueError("MonadToken requires <target> <offset> <act_id> <data>")

            offset = int(parts[1])
            act_id = int(parts[2])
            data = int(parts[3])

            return MonadToken(target=target, offset=offset, act_id=act_id, data=data, inline=False)

    def do_state(self, arg: str) -> None:
        """Display current simulation state: state

        Shows full summary of current system state from the last snapshot.

        Args:
            arg: Unused (for cmd.Cmd compatibility)
        """
        if not self._check_loaded():
            return

        if self._last_snapshot is None:
            print("No snapshot available", file=self.stdout)
            return

        print(format_snapshot_summary(self._last_snapshot), file=self.stdout)

    def do_pe(self, arg: str) -> None:
        """Display PE state: pe <id>

        Shows detailed state for the specified Processing Element.

        Args:
            arg: PE ID (integer)
        """
        if not self._check_loaded():
            return

        if not arg:
            print("Usage: pe <id>", file=self.stdout)
            return

        try:
            pe_id = int(arg)
        except ValueError:
            print(f"Invalid PE ID: {arg}", file=self.stdout)
            return

        if self._last_snapshot is None:
            print("No snapshot available", file=self.stdout)
            return

        if pe_id not in self._last_snapshot.pes:
            print(f"PE {pe_id} not found", file=self.stdout)
            return

        pe_snapshot = self._last_snapshot.pes[pe_id]
        print(format_pe_state(pe_snapshot), file=self.stdout)

    def do_sm(self, arg: str) -> None:
        """Display SM state: sm <id>

        Shows detailed state for the specified Structure Memory.

        Args:
            arg: SM ID (integer)
        """
        if not self._check_loaded():
            return

        if not arg:
            print("Usage: sm <id>", file=self.stdout)
            return

        try:
            sm_id = int(arg)
        except ValueError:
            print(f"Invalid SM ID: {arg}", file=self.stdout)
            return

        if self._last_snapshot is None:
            print("No snapshot available", file=self.stdout)
            return

        if sm_id not in self._last_snapshot.sms:
            print(f"SM {sm_id} not found", file=self.stdout)
            return

        sm_snapshot = self._last_snapshot.sms[sm_id]
        print(format_sm_state(sm_snapshot), file=self.stdout)

    def do_log(self, arg: str) -> None:
        """Display recent events: log [filter]

        Shows all events from history, optionally filtered by component or type.
        Filter format: 'pe:0', 'sm:1', 'Matched', etc.

        Args:
            arg: Optional filter string
        """
        if not self._event_history:
            print("No events in history", file=self.stdout)
            return

        filter_str = arg.strip() if arg else None
        events_to_show = self._event_history

        if filter_str:
            filtered = []
            for event in self._event_history:
                # Filter by component (pe:0, sm:1)
                if ":" in filter_str:
                    comp_type, comp_id = filter_str.split(":", 1)
                    if comp_type.lower() in event.component.lower():
                        try:
                            if str(int(comp_id)) in event.component:
                                filtered.append(event)
                        except ValueError:
                            pass
                # Filter by event type name
                elif filter_str in type(event).__name__:
                    filtered.append(event)
            events_to_show = filtered

        for event in events_to_show:
            print(format_event(event), file=self.stdout)

        if not events_to_show and filter_str:
            print(f"No events matching '{filter_str}'", file=self.stdout)

    def do_time(self, arg: str) -> None:
        """Display current simulation time: time

        Shows the current simulation time from the last snapshot.

        Args:
            arg: Unused (for cmd.Cmd compatibility)
        """
        print(f"Simulation time: {self._last_sim_time}", file=self.stdout)

    def do_reset(self, arg: str) -> None:
        """Reset simulation state: reset

        Clears the current simulation and resets all state. The backend
        remains ready to load a new program.

        Args:
            arg: Unused (for cmd.Cmd compatibility)
        """
        try:
            result = self.backend.send_command(ResetCmd(reload=False))
        except Exception as e:
            print(f"Error: {e}", file=self.stdout)
            return

        self._loaded = False
        self._event_history.clear()
        self._last_snapshot = None
        self._last_sim_time = 0.0
        print("Simulation reset", file=self.stdout)

    def do_quit(self, arg: str) -> bool:
        """Quit the monitor: quit

        Exits the REPL cleanly. Also triggered by Ctrl-D.

        Args:
            arg: Unused (for cmd.Cmd compatibility)

        Returns:
            True to exit cmdloop
        """
        return True

    # Alias for Ctrl-D
    def do_EOF(self, arg: str) -> bool:
        """Exit on Ctrl-D"""
        return True

    def default(self, line: str) -> None:
        """Handle unknown commands."""
        if line.strip():
            print(f"Unknown command: {line}", file=self.stdout)