package tools

import (
	"context"

	"code.nochebuena.dev/einherjar/mcp/internal/index"
	"github.com/modelcontextprotocol/go-sdk/mcp"
)

type listModulesInput struct{}

type moduleSummary struct {
	Name        string   `json:"name"`
	ImportPath  string   `json:"importPath"`
	Purpose     string   `json:"purpose"`
	GoVersion   string   `json:"goVersion"`
	SubPackages []string `json:"subPackages"`
}

type listModulesOutput struct {
	Modules []moduleSummary `json:"modules"`
}

func registerListModules(s *mcp.Server, idx *index.Index) {
	mcp.AddTool(s, &mcp.Tool{
		Name:        "list_modules",
		Description: "List every module of the Einherjar framework with its purpose, import path, Go version, and sub-packages. Use this first to discover what the framework offers.",
	}, func(ctx context.Context, req *mcp.CallToolRequest, _ listModulesInput) (*mcp.CallToolResult, listModulesOutput, error) {
		out := listModulesOutput{Modules: make([]moduleSummary, 0, len(idx.Modules))}
		for _, m := range idx.Modules {
			subs := make([]string, 0, len(m.SubPackages))
			for _, sp := range m.SubPackages {
				if sp.Name != "" {
					subs = append(subs, sp.Name)
				}
			}
			out.Modules = append(out.Modules, moduleSummary{
				Name:        m.Name,
				ImportPath:  m.ImportPath,
				Purpose:     m.Purpose,
				GoVersion:   m.GoVersion,
				SubPackages: subs,
			})
		}
		return jsonText(out), out, nil
	})
}