package builtin

import (
	"context"
	"encoding/json"
	"fmt"
	"strings"

	"nub/internal/skill"
	"nub/internal/tool"
)

// ReadSkillTool lädt den Body eines im Index (nur Name+Description)
// angekündigten Skills nach (5.5, Progressive Disclosure).
type ReadSkillTool struct {
	skills []skill.Skill
}

func NewReadSkillTool(skills []skill.Skill) *ReadSkillTool {
	return &ReadSkillTool{skills: skills}
}

func (*ReadSkillTool) Name() string { return "read_skill" }
func (*ReadSkillTool) Description() string {
	return "Lädt den vollständigen Inhalt eines Skills nach Name."
}

func (*ReadSkillTool) Schema() json.RawMessage {
	return json.RawMessage(`{
		"type": "object",
		"properties": {
			"name": {"type": "string"}
		},
		"required": ["name"]
	}`)
}

type readSkillInput struct {
	Name string `json:"name"`
}

func (t *ReadSkillTool) Run(ctx context.Context, input json.RawMessage, env tool.Env) (tool.Result, error) {
	var in readSkillInput
	if err := json.Unmarshal(input, &in); err != nil {
		return tool.Result{ForModel: "invalid input: " + err.Error(), IsError: true}, nil
	}

	for _, s := range t.skills {
		if s.Name == in.Name {
			return tool.Result{ForModel: s.Body, ForUI: SkillResult{Name: s.Name, Dir: s.Dir}}, nil
		}
	}

	names := make([]string, len(t.skills))
	for i, s := range t.skills {
		names[i] = s.Name
	}
	return tool.Result{
		ForModel: fmt.Sprintf("unknown skill %q. Available: %s", in.Name, strings.Join(names, ", ")),
		IsError:  true,
	}, nil
}

type SkillResult struct {
	Name string
	Dir  string
}