package tools

import (
	"context"

	"github.com/mark3labs/mcp-go/mcp"
)

const ListClustersName = "list_clusters"

// NewListClustersTool returns the schema for the list_clusters MCP Tool.
func NewListClustersTool() mcp.Tool {
	return mcp.NewTool(ListClustersName,
		mcp.WithDescription("List active Spark/YARN clusters configured for the agent. Returns the full Cluster struct (minus auth password) for every active cluster — this is the discovery root: from here the agent knows RM/SHS endpoints, auth flavor, and URL allowlists."),
	)
}

// ListClustersHandler lists configured clusters and returns only active ones.
func (d *Deps) ListClustersHandler(ctx context.Context, req mcp.CallToolRequest) (*mcp.CallToolResult, error) {
	callLog := startToolCall(ctx, d.Logger, ListClustersName, nil)
	defer callLog.End()

	all, err := d.ClusterRepo.List(ctx)
	if err != nil {
		callLog.WithError(err)
		return errResult("list_clusters: " + err.Error()), nil
	}

	// task_plan.md specifies active clusters only.
	active := all[:0]
	for _, c := range all {
		if c.IsActive {
			active = append(active, c)
		}
	}

	callLog.WithResult(map[string]any{"count": len(active)})
	return textResult(encodeJSON(active)), nil
}