// Package tools 实现统一工具注册表（4.8）：内置、声明式 HTTP、插件工具同一形态；
// 来源标记（builtin/plugin/user）、启用开关、确认策略由画像三清单决定（runmgr 执行）。
package tools

import (
	"encoding/json"
	"fmt"
	"sort"
	"strings"
	"sync"
	"time"

	core "agent-system-core"
)

// Executor 是无状态执行器：入参已校验，返回输出文本或错误。
type Executor func(rc ToolExecCtx, args json.RawMessage) (string, error)

// ToolExecCtx 供工具访问受控环境（当前项目/检索/工件写入）。
type ToolExecCtx interface {
	ProjectID() string
	ConversationID() string
	Retrieve(q core.RetrievalQuery) ([]core.RetrievalHit, error)
	WriteArtifact(name, kind, mime string, content []byte) (core.Artifact, error)
}

type tool struct {
	desc core.ToolDesc
	exec Executor
}

type Registry struct {
	mu    sync.RWMutex
	tools map[string]tool
}

func NewRegistry() *Registry { return &Registry{tools: map[string]tool{}} }

// Register 幂等注册（后注册覆盖同名；来源标记随之更新）。
// 声明式 HTTP 工具经 HTTPExecutor(spec, lookup) 绑定执行器。
func (r *Registry) Register(desc core.ToolDesc, exec Executor) error {
	if desc.Name == "" {
		return fmt.Errorf("tools: empty name")
	}
	if exec == nil {
		return fmt.Errorf("tools: %s has no executor", desc.Name)
	}
	r.mu.Lock()
	r.tools[desc.Name] = tool{desc: desc, exec: exec}
	r.mu.Unlock()
	return nil
}

func (r *Registry) UnregisterBySource(source core.SourceKind, pluginID string) {
	r.mu.Lock()
	for name, t := range r.tools {
		if t.desc.Source == source && (pluginID == "" || t.desc.PluginID == pluginID) {
			delete(r.tools, name)
		}
	}
	r.mu.Unlock()
}

func (r *Registry) List() []core.ToolDesc {
	r.mu.RLock()
	defer r.mu.RUnlock()
	out := make([]core.ToolDesc, 0, len(r.tools))
	for _, t := range r.tools {
		out = append(out, t.desc)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Name < out[j].Name })
	return out
}

func (r *Registry) Get(name string) (core.ToolDesc, Executor, bool) {
	r.mu.RLock()
	t, ok := r.tools[name]
	r.mu.RUnlock()
	return t.desc, t.exec, ok
}

// Execute 校验存在性并调用执行器；策略（allow/deny/confirm）与截断由 runmgr 负责。
func (r *Registry) Execute(rc ToolExecCtx, call core.ToolCallRequest) core.ToolCallResult {
	desc, exec, ok := r.Get(call.Name)
	if !ok {
		return core.ToolCallResult{CallID: call.CallID, Status: "error", Output: fmt.Sprintf("tool %q not found (registry miss)", call.Name)}
	}
	out, err := exec(rc, call.Arguments)
	if err != nil {
		return core.ToolCallResult{CallID: call.CallID, Status: "error", Output: err.Error()}
	}
	_ = desc
	return core.ToolCallResult{CallID: call.CallID, Status: "ok", Output: out, Truncated: false, Artifact: nil, }
}

// ---- 内置最小工具集（一切可禁用：画像三清单控制）----

// RegisterBuiltin 注册骨架期内置工具：时间、会话历史检索、知识检索、读文件、写工件。
func (r *Registry) RegisterBuiltin() error {
	if err := r.Register(core.ToolDesc{
		Name: "time_now", Description: "获取当前时间（RFC3339）与时区", Source: core.SourceBuiltin,
		Parameters: json.RawMessage(`{"type":"object","properties":{}}`),
	}, func(rc ToolExecCtx, args json.RawMessage) (string, error) {
		return time.Now().Format(time.RFC3339), nil
	}); err != nil {
		return err
	}
	if err := r.Register(core.ToolDesc{
		Name: "knowledge_search", Description: "在项目知识与插件知识库中做全文检索，返回命中片段", Source: core.SourceBuiltin,
		Parameters: json.RawMessage(`{"type":"object","properties":{"query":{"type":"string","description":"检索词"}},"required":["query"]}`),
	}, func(rc ToolExecCtx, args json.RawMessage) (string, error) {
		var a struct{ Query string `json:"query"`; TopK int `json:"topK"` }
		if len(args) > 0 {
			if err := json.Unmarshal(args, &a); err != nil {
				return "", fmt.Errorf("knowledge_search: bad args: %w", err)
			}
		}
		if a.Query == "" {
			return "", fmt.Errorf("knowledge_search: query is required")
		}
		hits, err := rc.Retrieve(core.RetrievalQuery{ProjectID: rc.ProjectID(), Text: a.Query, TopK: a.TopK})
		if err != nil {
			return "", err
		}
		if len(hits) == 0 {
			return "（无命中）", nil
		}
		var sb strings.Builder
		for i, h := range hits {
			fmt.Fprintf(&sb, "[%d] %s（来源 %s，得分 %.2f）\n%s\n\n", i+1, h.Doc.Title, h.Doc.Source, h.Score, h.Doc.Chunk)
		}
		return sb.String(), nil
	}); err != nil {
		return err
	}
	if err := r.Register(core.ToolDesc{
		Name: "write_artifact", Description: "把生成内容写入工件（文档/数据），返回工件 ID 与名称", Source: core.SourceBuiltin,
		Parameters: json.RawMessage(`{"type":"object","properties":{"name":{"type":"string"},"kind":{"type":"string","enum":["document","data"]},"content":{"type":"string"}},"required":["name","content"]}`),
	}, func(rc ToolExecCtx, args json.RawMessage) (string, error) {
		var a struct {
			Name    string `json:"name"`
			Kind    string `json:"kind"`
			Content string `json:"content"`
		}
		if err := json.Unmarshal(args, &a); err != nil {
			return "", err
		}
		if a.Name == "" {
			return "", fmt.Errorf("write_artifact: name required")
		}
		kind := a.Kind
		if kind == "" {
			kind = "document"
		}
		mime := "text/markdown"
		if kind == "data" {
			mime = "application/json"
		}
		art, err := rc.WriteArtifact(a.Name, kind, mime, []byte(a.Content))
		if err != nil {
			return "", err
		}
		return fmt.Sprintf("已写入工件 %s（%s，%d 字节）", art.Name, art.ID, art.Size), nil
	}); err != nil {
		return err
	}
	return nil
}