"""Change Management domain tools for ServiceNow MCP server."""

from mcp.server.fastmcp import FastMCP

from servicenow_mcp.auth import BasicAuthProvider
from servicenow_mcp.choices import ChoiceRegistry
from servicenow_mcp.client import ServiceNowClient
from servicenow_mcp.config import Settings
from servicenow_mcp.decorators import tool_handler
from servicenow_mcp.policy import check_table_access, mask_sensitive_fields, write_gate
from servicenow_mcp.utils import ServiceNowQuery, format_response


def register_tools(
    mcp: FastMCP,
    settings: Settings,
    auth_provider: BasicAuthProvider,
    choices: ChoiceRegistry | None = None,
) -> None:
    """Register Change Management domain tools.

    Args:
        mcp: FastMCP instance for tool registration
        settings: Server configuration settings
        auth_provider: Authentication provider for ServiceNow API
        choices: Optional choice registry for resolving field values
    """

    @mcp.tool()
    @tool_handler
    async def change_list(
        state: str = "",
        type: str = "",
        risk: str = "",
        assignment_group: str = "",
        fields: str = "number,short_description,state,type,risk,assignment_group,sys_created_on",
        limit: int = 20,
        *,
        correlation_id: str,
    ) -> str:
        """List change requests with optional filters.

        Args:
            state: Change state (new, assess, authorize, scheduled, implement, review, closed, canceled)
            type: Change type (standard, normal, emergency)
            risk: Risk level
            assignment_group: sys_id or name of assignment group
            fields: Comma-separated list of fields to return (empty for all)
            limit: Maximum results to return (default 20)
        """
        check_table_access("change_request")

        q = ServiceNowQuery()
        if state:
            resolved = await choices.resolve("change_request", "state", state.lower()) if choices else state
            q = q.equals_if("state", resolved, True)
        q = q.equals_if("type", type, bool(type))
        q = q.equals_if("risk", risk, bool(risk))
        q = q.equals_if("assignment_group", assignment_group, bool(assignment_group))

        query = q.build()
        field_list = [f.strip() for f in fields.split(",") if f.strip()] if fields else None

        async with ServiceNowClient(settings, auth_provider) as client:
            result = await client.query_records(
                table="change_request",
                query=query,
                fields=field_list,
                display_values=True,
                limit=limit,
            )
            masked = [mask_sensitive_fields(r) for r in result["records"]]
            return format_response(data=masked, correlation_id=correlation_id)

    @mcp.tool()
    @tool_handler
    async def change_get(number: str, *, correlation_id: str) -> str:
        """Fetch change request by CHG number.

        Args:
            number: Change request number (must start with CHG prefix)
        """
        check_table_access("change_request")

        if not number.upper().startswith("CHG"):
            return format_response(
                data=None,
                correlation_id=correlation_id,
                status="error",
                error=f"Invalid change request number: {number}. Must start with CHG prefix.",
            )

        async with ServiceNowClient(settings, auth_provider) as client:
            result = await client.query_records(
                table="change_request",
                query=ServiceNowQuery().equals("number", number.upper()).build(),
                display_values=True,
                limit=1,
            )
            if not result["records"]:
                return format_response(
                    data=None,
                    correlation_id=correlation_id,
                    status="error",
                    error=f"Change request {number} not found.",
                )
            masked = mask_sensitive_fields(result["records"][0])
            return format_response(data=masked, correlation_id=correlation_id)

    @mcp.tool()
    @tool_handler
    async def change_create(
        short_description: str,
        description: str = "",
        type: str = "normal",
        risk: str = "",
        assignment_group: str = "",
        start_date: str = "",
        end_date: str = "",
        *,
        correlation_id: str,
    ) -> str:
        """Create a new change request.

        Args:
            short_description: Brief description (required)
            description: Detailed description
            type: Change type (standard, normal, emergency, default: normal)
            risk: Risk level
            assignment_group: sys_id or name of assignment group
            start_date: Planned start date
            end_date: Planned end date
        """
        check_table_access("change_request")

        blocked = write_gate("change_request", settings, correlation_id)
        if blocked:
            return blocked

        if not short_description or not short_description.strip():
            return format_response(
                data=None,
                correlation_id=correlation_id,
                status="error",
                error="short_description is required and cannot be empty.",
            )

        valid_types = ["standard", "normal", "emergency"]
        if type and type not in valid_types:
            return format_response(
                data=None,
                correlation_id=correlation_id,
                status="error",
                error=f"type must be one of {valid_types}, got '{type}'.",
            )

        record_data = {
            "short_description": short_description,
            "type": type,
        }

        if description:
            record_data["description"] = description
        if risk:
            record_data["risk"] = risk
        if assignment_group:
            record_data["assignment_group"] = assignment_group
        if start_date:
            record_data["start_date"] = start_date
        if end_date:
            record_data["end_date"] = end_date

        async with ServiceNowClient(settings, auth_provider) as client:
            created = await client.create_record("change_request", record_data)
            masked = mask_sensitive_fields(created)
            return format_response(data=masked, correlation_id=correlation_id)

    @mcp.tool()
    @tool_handler
    async def change_update(
        number: str,
        short_description: str = "",
        description: str = "",
        type: str = "",
        risk: str = "",
        assignment_group: str = "",
        state: str = "",
        *,
        correlation_id: str,
    ) -> str:
        """Update an existing change request by CHG number.

        Args:
            number: Change request number (must start with CHG prefix)
            short_description: Brief description
            description: Detailed description
            type: Change type (standard, normal, emergency)
            risk: Risk level
            assignment_group: sys_id or name of assignment group
            state: Change state (new, assess, authorize, scheduled, implement, review, closed, canceled)
        """
        check_table_access("change_request")

        blocked = write_gate("change_request", settings, correlation_id)
        if blocked:
            return blocked

        if not number.upper().startswith("CHG"):
            return format_response(
                data=None,
                correlation_id=correlation_id,
                status="error",
                error=f"Invalid change request number: {number}. Must start with CHG prefix.",
            )

        async with ServiceNowClient(settings, auth_provider) as client:
            result = await client.query_records(
                table="change_request",
                query=ServiceNowQuery().equals("number", number.upper()).build(),
                limit=1,
            )
            if not result["records"]:
                return format_response(
                    data=None,
                    correlation_id=correlation_id,
                    status="error",
                    error=f"Change request {number} not found.",
                )

            sys_id = result["records"][0]["sys_id"]

            changes = {}
            if short_description:
                changes["short_description"] = short_description
            if description:
                changes["description"] = description
            if type:
                changes["type"] = type
            if risk:
                changes["risk"] = risk
            if assignment_group:
                changes["assignment_group"] = assignment_group
            if state:
                changes["state"] = await choices.resolve("change_request", "state", state.lower()) if choices else state

            if not changes:
                return format_response(
                    data=None,
                    correlation_id=correlation_id,
                    status="error",
                    error="No fields to update provided.",
                )

            updated = await client.update_record("change_request", sys_id, changes)
            masked = mask_sensitive_fields(updated)
            return format_response(data=masked, correlation_id=correlation_id)

    @mcp.tool()
    @tool_handler
    async def change_tasks(
        number: str,
        fields: str = "number,short_description,state,assignment_group,assigned_to,sys_created_on",
        limit: int = 20,
        *,
        correlation_id: str,
    ) -> str:
        """Get change tasks for a change request.

        Args:
            number: Change request number (must start with CHG prefix)
            fields: Comma-separated list of fields to return (empty for all)
            limit: Maximum results to return (default 20)
        """
        check_table_access("change_task")

        if not number.upper().startswith("CHG"):
            return format_response(
                data=None,
                correlation_id=correlation_id,
                status="error",
                error=f"Invalid change request number: {number}. Must start with CHG prefix.",
            )

        field_list = [f.strip() for f in fields.split(",") if f.strip()] if fields else None

        async with ServiceNowClient(settings, auth_provider) as client:
            result = await client.query_records(
                table="change_task",
                query=ServiceNowQuery().equals("change_request.number", number.upper()).build(),
                fields=field_list,
                display_values=True,
                limit=limit,
            )
            masked = [mask_sensitive_fields(r) for r in result["records"]]
            return format_response(data=masked, correlation_id=correlation_id)

    @mcp.tool()
    @tool_handler
    async def change_add_comment(
        number: str,
        comment: str = "",
        work_note: str = "",
        *,
        correlation_id: str,
    ) -> str:
        """Add comment or work note to a change request.

        Args:
            number: Change request number (must start with CHG prefix)
            comment: Customer-visible comment
            work_note: Internal work note
        """
        check_table_access("change_request")

        blocked = write_gate("change_request", settings, correlation_id)
        if blocked:
            return blocked

        if not number.upper().startswith("CHG"):
            return format_response(
                data=None,
                correlation_id=correlation_id,
                status="error",
                error=f"Invalid change request number: {number}. Must start with CHG prefix.",
            )

        if not comment and not work_note:
            return format_response(
                data=None,
                correlation_id=correlation_id,
                status="error",
                error="At least one of comment or work_note must be provided.",
            )

        async with ServiceNowClient(settings, auth_provider) as client:
            result = await client.query_records(
                table="change_request",
                query=ServiceNowQuery().equals("number", number.upper()).build(),
                limit=1,
            )
            if not result["records"]:
                return format_response(
                    data=None,
                    correlation_id=correlation_id,
                    status="error",
                    error=f"Change request {number} not found.",
                )

            sys_id = result["records"][0]["sys_id"]

            changes = {}
            if comment:
                changes["comments"] = comment
            if work_note:
                changes["work_notes"] = work_note

            updated = await client.update_record("change_request", sys_id, changes)
            masked = mask_sensitive_fields(updated)
            return format_response(data=masked, correlation_id=correlation_id)
