"""TaskWarrior MCP Server implementation."""

import asyncio
import json
import logging
import os
import sys
from typing import Any

from mcp.server.fastmcp import FastMCP

# reconfigure UnicodeEncodeError prone default (i.e. windows-1252) to utf-8
if sys.platform == "win32" and os.environ.get('PYTHONIOENCODING') is None:
    sys.stdin.reconfigure(encoding="utf-8")
    sys.stdout.reconfigure(encoding="utf-8")
    sys.stderr.reconfigure(encoding="utf-8")

logger = logging.getLogger('mcp_taskwarrior_server')


class TaskWarriorError(Exception):
    """Base exception for TaskWarrior operations."""

    pass


class TaskWarriorServer:
    """Server class for TaskWarrior MCP operations."""

    def __init__(self) -> None:
        """Initialize the TaskWarrior server."""
        self._check_taskwarrior_installed()

    def _check_taskwarrior_installed(self) -> None:
        """Check if TaskWarrior is installed and accessible."""
        # This will be checked on first command execution
        pass

    async def _run_task_command(
        self, *args: str, input_text: str | None = None
    ) -> tuple[str, str, int]:
        """Execute a TaskWarrior command and return stdout, stderr, return code.
        
        Args:
            *args: Command arguments to pass to task command
            input_text: Optional input text to send to stdin
            
        Returns:
            Tuple of (stdout, stderr, return_code)
            
        Raises:
            TaskWarriorError: If taskwarrior is not installed or command fails
        """
        try:
            # Use rc.confirmation:off to avoid interactive prompts
            # Use rc.bulk:0 to avoid bulk operation confirmations
            cmd = ["task", "rc.confirmation:off", "rc.bulk:0"] + list(args)
            
            process = await asyncio.create_subprocess_exec(
                *cmd,
                stdout=asyncio.subprocess.PIPE,
                stderr=asyncio.subprocess.PIPE,
                stdin=asyncio.subprocess.PIPE if input_text else None,
            )
            
            stdout_bytes, stderr_bytes = await process.communicate(
                input_text.encode() if input_text else None
            )
            
            stdout = stdout_bytes.decode('utf-8', errors='replace')
            stderr = stderr_bytes.decode('utf-8', errors='replace')
            return_code = process.returncode
            
            if return_code != 0:
                error_msg = stderr.strip() or stdout.strip() or "Unknown error"
                # Check if taskwarrior is not installed
                error_lower = error_msg.lower()
                if ("command not found" in error_lower or "not found" in error_lower):
                    raise TaskWarriorError(
                        "TaskWarrior is not installed or not in PATH. "
                        "Please install TaskWarrior to use this server."
                    )
                raise TaskWarriorError(f"TaskWarrior command failed: {error_msg}")
            
            return stdout, stderr, return_code
            
        except FileNotFoundError:
            raise TaskWarriorError(
                "TaskWarrior is not installed or not in PATH. "
                "Please install TaskWarrior to use this server."
            ) from None
        except Exception as e:
            if isinstance(e, TaskWarriorError):
                raise
            raise TaskWarriorError(
                f"Error executing TaskWarrior command: {str(e)}"
            ) from e

    async def list_tasks(self, filter_expr: str | None = None) -> list[dict[str, Any]]:
        """List tasks matching the optional filter.
        
        Args:
            filter_expr: Optional filter expression (e.g., "project:Home", "+work")
            
        Returns:
            List of task dictionaries from JSON export
        """
        args = []
        if filter_expr:
            args.append(filter_expr)
        args.append("export")
        
        stdout, _, _ = await self._run_task_command(*args)
        
        # Parse JSON output
        try:
            # TaskWarrior export outputs JSON array, but may have trailing newlines
            stdout = stdout.strip()
            if not stdout:
                return []
            tasks = json.loads(stdout)
            if not isinstance(tasks, list):
                return [tasks] if tasks else []
            return tasks
        except json.JSONDecodeError as e:
            logger.error(f"Failed to parse TaskWarrior JSON output: {e}")
            logger.debug(f"Output was: {stdout}")
            raise TaskWarriorError(
                f"Failed to parse TaskWarrior output: {str(e)}"
            ) from e

    async def add_task(
        self,
        description: str,
        project: str | None = None,
        priority: str | None = None,
        due: str | None = None,
        tags: list[str] | None = None,
    ) -> dict[str, Any]:
        """Add a new task to TaskWarrior.
        
        Args:
            description: Task description (required)
            project: Optional project name
            priority: Optional priority (H, M, or L)
            due: Optional due date (ISO format or TaskWarrior date format)
            tags: Optional list of tags
            
        Returns:
            Dictionary with task information including UUID
        """
        args = ["add", description]
        
        if project:
            args.append(f"project:{project}")
        
        if priority:
            if priority.upper() not in ["H", "M", "L"]:
                raise ValueError(f"Priority must be H, M, or L, got: {priority}")
            args.append(f"priority:{priority.upper()}")
        
        if due:
            args.append(f"due:{due}")
        
        if tags:
            for tag in tags:
                args.append(f"+{tag}")
        
        stdout, stderr, _ = await self._run_task_command(*args)
        
        # Extract UUID from output
        # TaskWarrior output format: "Created task 123.\n\nUUID: <uuid>"
        uuid = None
        for line in stdout.split('\n'):
            if line.startswith('UUID:'):
                uuid = line.split(':', 1)[1].strip()
                break
        
        # If UUID not found in stdout, try to get it by listing the newest task
        if not uuid:
            # Get the newest task to find the UUID
            tasks = await self.list_tasks("status:pending")
            if tasks:
                # Sort by entry date (most recent first)
                tasks.sort(key=lambda t: t.get('entry', ''), reverse=True)
                uuid = tasks[0].get('uuid')
        
        return {
            "description": description,
            "uuid": uuid,
            "project": project,
            "priority": priority.upper() if priority else None,
            "due": due,
            "tags": tags or [],
            "output": stdout.strip(),
        }

    async def done_task(self, uuid: str) -> dict[str, Any]:
        """Mark a task as completed.
        
        Args:
            uuid: Task UUID (stable identifier)
            
        Returns:
            Dictionary with completion information
        """
        stdout, stderr, _ = await self._run_task_command(uuid, "done")
        
        return {
            "uuid": uuid,
            "status": "completed",
            "output": stdout.strip(),
        }

    async def delete_task(self, uuid: str) -> dict[str, Any]:
        """Delete a task.
        
        Args:
            uuid: Task UUID (stable identifier)
            
        Returns:
            Dictionary with deletion information
        """
        stdout, stderr, _ = await self._run_task_command(uuid, "delete")
        
        return {
            "uuid": uuid,
            "status": "deleted",
            "output": stdout.strip(),
        }

    async def manage_context(
        self, action: str, name: str | None = None
    ) -> dict[str, Any]:
        """Manage TaskWarrior contexts.
        
        Args:
            action: One of "set", "list", "show", "none"
            name: Context name (required for "set" action)
            
        Returns:
            Dictionary with context information
        """
        if action not in ["set", "list", "show", "none"]:
            raise ValueError(
                f"Action must be one of: set, list, show, none. Got: {action}"
            )
        
        if action == "set" and not name:
            raise ValueError("Context name is required for 'set' action")
        
        args = ["context"]
        
        if action == "set":
            args.append(name)
        elif action == "none":
            args.append("none")
        else:
            args.append(action)
        
        stdout, stderr, _ = await self._run_task_command(*args)
        
        result: dict[str, Any] = {
            "action": action,
            "output": stdout.strip(),
        }
        
        if action == "set" and name:
            result["context"] = name
        elif action == "show":
            # Parse the context show output to extract context name
            lines = stdout.strip().split('\n')
            for line in lines:
                if line.startswith("Context '") and "'" in line:
                    context_name = line.split("'")[1]
                    result["context"] = context_name
                    break
        elif action == "list":
            # Parse context list output
            contexts = []
            for line in stdout.strip().split('\n'):
                if line.strip() and not line.startswith("Name"):
                    parts = line.split()
                    if len(parts) >= 2:
                        ctx_name = parts[0]
                        if ctx_name not in [c.get("name") for c in contexts]:
                            contexts.append({"name": ctx_name})
            result["contexts"] = contexts
        
        return result


def create_server(host: str = "127.0.0.1", port: int = 8080) -> FastMCP:
    """Create and configure the FastMCP server.
    
    Args:
        host: Host to bind to for remote transport
        port: Port to bind to for remote transport
        
    Returns:
        Configured FastMCP server instance
    """
    mcp = FastMCP("TaskWarrior", host=host, port=port)
    
    # Create a TaskWarriorServer instance
    taskwarrior = TaskWarriorServer()
    
    @mcp.tool()
    async def list_tasks(filter_expr: str | None = None) -> str:
        """List tasks with optional filter.
        
        Args:
            filter_expr: Optional filter expression
                (e.g., "project:Home", "+work", "status:pending")
            
        Returns:
            JSON string of tasks matching the filter
        """
        try:
            tasks = await taskwarrior.list_tasks(filter_expr)
            return json.dumps(tasks, indent=2)
        except Exception as e:
            logger.error(f"Error listing tasks: {e}")
            return json.dumps({"error": str(e)})
    
    @mcp.tool()
    async def add_task(
        description: str,
        project: str | None = None,
        priority: str | None = None,
        due: str | None = None,
        tags: list[str] | None = None,
    ) -> str:
        """Add a new task to TaskWarrior.
        
        Args:
            description: Task description (required)
            project: Optional project name
            priority: Optional priority (H, M, or L)
            due: Optional due date (ISO format or TaskWarrior date format
                like "tomorrow", "2024-12-25")
            tags: Optional list of tags
            
        Returns:
            JSON string with task information including UUID
        """
        try:
            result = await taskwarrior.add_task(
                description=description,
                project=project,
                priority=priority,
                due=due,
                tags=tags,
            )
            return json.dumps(result, indent=2)
        except Exception as e:
            logger.error(f"Error adding task: {e}")
            return json.dumps({"error": str(e)})
    
    @mcp.tool()
    async def done_task(uuid: str) -> str:
        """Mark a task as completed.
        
        Args:
            uuid: Task UUID (stable identifier, not the numeric ID)
            
        Returns:
            JSON string with completion information
        """
        try:
            result = await taskwarrior.done_task(uuid)
            return json.dumps(result, indent=2)
        except Exception as e:
            logger.error(f"Error marking task as done: {e}")
            return json.dumps({"error": str(e)})
    
    @mcp.tool()
    async def delete_task(uuid: str) -> str:
        """Delete a task.
        
        Args:
            uuid: Task UUID (stable identifier, not the numeric ID)
            
        Returns:
            JSON string with deletion information
        """
        try:
            result = await taskwarrior.delete_task(uuid)
            return json.dumps(result, indent=2)
        except Exception as e:
            logger.error(f"Error deleting task: {e}")
            return json.dumps({"error": str(e)})
    
    @mcp.tool()
    async def context(action: str, name: str | None = None) -> str:
        """Manage TaskWarrior contexts.
        
        Args:
            action: One of "set", "list", "show", "none"
            name: Context name (required for "set" action, optional otherwise)
            
        Returns:
            JSON string with context information
        """
        try:
            result = await taskwarrior.manage_context(action, name)
            return json.dumps(result, indent=2)
        except Exception as e:
            logger.error(f"Error managing context: {e}")
            return json.dumps({"error": str(e)})
    
    return mcp


async def main(transport_type: str, host: str, port: int) -> None:
    """Start the server with the specified transport.
    
    Args:
        transport_type: Transport type ("stdio" or "remote")
        host: Host to bind to for remote transport
        port: Port to bind to for remote transport
    """
    logger.info("Starting MCP TaskWarrior Server")
    logger.info(f"Starting TaskWarrior MCP Server with {transport_type} transport")
    
    # Create the server with host and port
    mcp = create_server(host=host, port=port)
    
    # Run the server with the appropriate transport
    if transport_type == "stdio":
        logger.info("Server running with stdio transport")
        await mcp.run_stdio_async()
    else:  # remote transport
        logger.info(f"Server running with remote transport on {host}:{port}")
        await mcp.run_sse_async()