package agent

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

	"git.gopher.ink/mirrors2/AutoZero/llm"
	"git.gopher.ink/mirrors2/AutoZero/tools"
)

// SkillTool 构造 load_skill 工具：按名加载 SKILL.md 正文进上下文。
// 若 skill 声明了 allowed-tools，则从加载起后续轮次的工具表收敛到
// 该白名单（∪ load_skill 自身），未授权的工具调用会被拒绝。
// 过滤持续到会话结束或加载下一个带 allowed-tools 的 skill（借鉴 ccb
// skill 的 contextModifier 思路，简化为会话级）。
func (a *Agent) SkillTool() *tools.Tool {
	return &tools.Tool{
		Name:            "load_skill",
		Description:     "Load a skill's full instructions by name (available skills are listed in the system prompt). Call this before performing a task that matches a skill.",
		ReadOnly:        true,
		ConcurrencySafe: true,
		Parameters: map[string]any{
			"type": "object",
			"properties": map[string]any{
				"name": map[string]any{"type": "string", "description": "Skill name from the system prompt list"},
			},
			"required": []string{"name"},
		},
		Run: func(_ context.Context, input string) (tools.Result, error) {
			var p struct {
				Name string `json:"name"`
			}
			if err := json.Unmarshal([]byte(input), &p); err != nil {
				return tools.Result{}, fmt.Errorf("invalid load_skill input: %w", err)
			}
			for _, s := range a.Skills {
				if s.Name != p.Name {
					continue
				}
				if len(s.AllowedTools) > 0 {
					filter := map[string]bool{"load_skill": true}
					for _, t := range s.AllowedTools {
						filter[t] = true
					}
					a.skillFilter = filter
				}
				return tools.TextResult(s.Body), nil
			}
			return tools.Result{}, fmt.Errorf("unknown skill %q", p.Name)
		},
	}
}

// toolDefs 返回当前轮次可见的工具声明：skill 白名单生效时做交集过滤。
func (a *Agent) toolDefs() []llm.ToolDef {
	defs := a.Tools.Defs()
	if a.skillFilter == nil {
		return defs
	}
	out := make([]llm.ToolDef, 0, len(defs))
	for _, d := range defs {
		if a.skillFilter[d.Name] {
			out = append(out, d)
		}
	}
	return out
}