package runtime

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

	"agent-native/runtime/llm"
	"agent-native/runtime/tools"
)

// ---- N2 WP1：前缀稳定契约（缓存友好的机器钉住：同一注册序列 → 逐字节确定）----

type contractTool struct {
	name, desc string
	deferred   bool
}

func (t contractTool) Name() string                { return t.name }
func (t contractTool) Description() string         { return t.desc }
func (t contractTool) Parameters() json.RawMessage { return json.RawMessage(`{"type":"object","properties":{}}`) }
func (t contractTool) Execute(_ context.Context, _ json.RawMessage) (tools.Result, error) {
	return tools.Result{Content: "ok"}, nil
}
func (t contractTool) Exposure() string {
	if t.deferred {
		return tools.ExposureDeferred
	}
	return tools.ExposureDirect
}

func buildContractRegistry() *tools.Registry {
	reg := tools.NewRegistry("")
	reg.Register(contractTool{name: "read_file", desc: "读文件"})
	reg.Register(contractTool{name: "write_file", desc: "写文件"})
	reg.Register(contractTool{name: "grep", desc: "搜索", deferred: true})
	return reg
}

func TestSystemTextDeterministicAcrossIdenticalBuilds(t *testing.T) {
	a := systemText(Config{SystemPrompt: "sys", Tools: buildContractRegistry()})
	b := systemText(Config{SystemPrompt: "sys", Tools: buildContractRegistry()})
	if a != b {
		t.Fatalf("同一注册序列的系统文本必须逐字节一致：\n%q\nvs\n%q", a, b)
	}
	// 契约内容：直接工具全在清单内且按注册序；deferred 工具不进入清单。
	idx := strings.Index(a, "read_file")
	if idx < 0 || strings.Index(a, "write_file") < idx {
		t.Fatalf("直接工具须按注册序出现：%q", a)
	}
	if strings.Contains(a, "grep") {
		t.Fatalf("deferred 工具不得出现在系统文本：%q", a)
	}
	// 元工具注入位置确定（tool_search/call_tool 存在且在 Decls 中）。
	decls := buildContractRegistry().Decls()
	names := []string{}
	for _, d := range decls {
		names = append(names, d.Name)
	}
	if len(names) != 4 || names[0] != "read_file" || names[1] != "write_file" {
		t.Fatalf("Decls 顺序契约：%v", names)
	}
	if names[2] != "tool_search" && names[3] != "tool_search" {
		if names[2] != "call_tool" && names[3] != "call_tool" {
			t.Fatalf("元工具缺失：%v", names)
		}
	}
	var _ = llm.ToolDecl{} // 保持导入面稳定
}