// Package mcp 实现 MCP 协议网关，把工具注册到 NATS 并响应调用。
package mcp

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"

	sharedbus "github.com/sundynix/sundynix-shared/bus"
	"github.com/sundynix/sundynix-shared/contract"

	"github.com/sundynix/sundynix-mcp-go/internal/history"
	"github.com/sundynix/sundynix-mcp-go/internal/memory"
	"github.com/sundynix/sundynix-mcp-go/internal/office"
	"github.com/sundynix/sundynix-mcp-go/internal/rag"
	"github.com/sundynix/sundynix-mcp-go/internal/search"
)

// Gateway 暴露 MCP 协议端点，经共享 bus 订阅 sundynix.tools.go.* 响应调用。
type Gateway struct {
	bus     *sharedbus.Bus
	search  *search.Hybrid
	memory  *memory.Store
	history *history.Store
	rag     *rag.Engine
}

func NewGateway(b *sharedbus.Bus, s *search.Hybrid, m *memory.Store, h *history.Store, r *rag.Engine) *Gateway {
	return &Gateway{bus: b, search: s, memory: m, history: h, rag: r}
}

// Serve 以队列组通配订阅 sundynix.tools.go.>，按工具名分发并阻塞。
func (g *Gateway) Serve(ctx context.Context) error {
	unsub, err := g.bus.ServeTool(contract.SubjectToolsGoAll, contract.QueueToolsGo, g.dispatch)
	if err != nil {
		return err
	}
	defer func() { _ = unsub() }()
	log.Printf("[mcp_go] tools ready on %s (queue=%s): wiki_search, kb_ingest, kb_search, kb_graph, report_render, memory_*, history_*, echo",
		contract.SubjectToolsGoAll, contract.QueueToolsGo)
	<-ctx.Done()
	return ctx.Err()
}

// dispatch 按 ToolCall.Tool 路由到具体工具实现。
func (g *Gateway) dispatch(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	log.Printf("[mcp_go] tool=%s task=%s args=%v", call.Tool, call.TaskID, call.Args)
	switch call.Tool {
	case "wiki_search":
		return g.wikiSearch(ctx, call)
	case "kb_ingest":
		return g.kbIngest(ctx, call)
	case "kb_search":
		return g.kbSearch(ctx, call)
	case "kb_graph":
		return g.kbGraph(ctx, call)
	case "report_render":
		return g.reportRender(ctx, call)
	case "report_store":
		return g.reportStore(ctx, call)
	case "report_export":
		return g.reportExport(ctx, call)
	case "external_api":
		return g.externalAPI(ctx, call)
	case "health":
		data, _ := json.Marshal(g.rag.Status())
		return &contract.ToolResult{OK: true, Content: string(data)}
	case "memory_get":
		return g.memoryGet(ctx, call)
	case "memory_upsert":
		return g.memoryUpsert(ctx, call)
	case "history_get":
		return g.historyGet(ctx, call)
	case "history_append":
		return g.historyAppend(ctx, call)
	case "echo":
		return &contract.ToolResult{OK: true, Content: fmt.Sprint(call.Args["text"])}
	default:
		return &contract.ToolResult{OK: false, Error: "unknown tool: " + call.Tool}
	}
}

// memoryGet 召回某用户的常驻画像（已渲染为可注入 prompt 的多行文本）。
func (g *Gateway) memoryGet(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	uid, _ := call.Args["user_id"].(string)
	profile, err := g.memory.Get(ctx, uid)
	if err != nil {
		return &contract.ToolResult{OK: false, Error: "memory_get: " + err.Error()}
	}
	return &contract.ToolResult{OK: true, Content: profile}
}

// historyGet 召回某会话最近多轮历史，Content 为 JSON 数组 [{role,content},...]（正序）。
func (g *Gateway) historyGet(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	session, _ := call.Args["session_id"].(string)
	turns, err := g.history.Get(ctx, session)
	if err != nil {
		return &contract.ToolResult{OK: false, Error: "history_get: " + err.Error()}
	}
	data, _ := json.Marshal(turns)
	return &contract.ToolResult{OK: true, Content: string(data)}
}

// historyAppend 追加一条会话消息（session_id + role + content）。
func (g *Gateway) historyAppend(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	session, _ := call.Args["session_id"].(string)
	role, _ := call.Args["role"].(string)
	content, _ := call.Args["content"].(string)
	if session == "" || role == "" {
		return &contract.ToolResult{OK: false, Error: "history_append: session_id 和 role 必填"}
	}
	if err := g.history.Append(ctx, session, role, content); err != nil {
		return &contract.ToolResult{OK: false, Error: "history_append: " + err.Error()}
	}
	return &contract.ToolResult{OK: true}
}

// memoryUpsert 写入/更新一条画像偏好（user_id + key + value）。
func (g *Gateway) memoryUpsert(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	uid, _ := call.Args["user_id"].(string)
	key, _ := call.Args["key"].(string)
	val, _ := call.Args["value"].(string)
	if uid == "" || key == "" {
		return &contract.ToolResult{OK: false, Error: "memory_upsert: user_id 和 key 必填"}
	}
	if err := g.memory.Upsert(ctx, uid, key, val); err != nil {
		return &contract.ToolResult{OK: false, Error: "memory_upsert: " + err.Error()}
	}
	return &contract.ToolResult{OK: true, Content: fmt.Sprintf("已记住 %s 的「%s」", uid, key)}
}

// wikiSearch 经 RAG 引擎做向量检索（embedding + Milvus）。
// RAG 未就绪时降级返回空命中（不阻断图执行）。
func (g *Gateway) wikiSearch(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	q, _ := call.Args["q"].(string)
	kb, _ := call.Args["kb"].(string)
	topK := 5
	if v, ok := call.Args["topK"].(float64); ok && v > 0 {
		topK = int(v)
	}
	if !g.rag.Ready() {
		return &contract.ToolResult{OK: true, Content: "[wiki_search] RAG 未配置（需 embedding + Milvus），无召回"}
	}
	hits, err := g.rag.Search(ctx, kb, q, topK)
	if err != nil {
		return &contract.ToolResult{OK: false, Error: "wiki_search: " + err.Error()}
	}
	var b strings.Builder
	fmt.Fprintf(&b, "[wiki_search] 命中 %d 条（Milvus 向量检索）：\n", len(hits))
	for i, h := range hits {
		fmt.Fprintf(&b, "%d. (%.3f) %s\n", i+1, h.Score, h.Text)
	}
	return &contract.ToolResult{OK: true, Content: strings.TrimRight(b.String(), "\n")}
}

// kbSearch 检索台用：返回结构化命中 JSON [{text,score},...]（供检索台展示分数）。
func (g *Gateway) kbSearch(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	q, _ := call.Args["q"].(string)
	kb, _ := call.Args["kb"].(string)
	topK := 5
	if v, ok := call.Args["topK"].(float64); ok && v > 0 {
		topK = int(v)
	}
	if !g.rag.Ready() {
		return &contract.ToolResult{OK: true, Content: "[]"}
	}
	hits, err := g.rag.Search(ctx, kb, q, topK)
	if err != nil {
		return &contract.ToolResult{OK: false, Error: "kb_search: " + err.Error()}
	}
	data, _ := json.Marshal(hits)
	return &contract.ToolResult{OK: true, Content: string(data)}
}

// kbGraph 返回某知识库的图谱三元组 JSON [{s,p,o},...]（供 UI 可视化 Neo4j 情况）。
func (g *Gateway) kbGraph(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	kb, _ := call.Args["kb"].(string)
	limit := 100
	if v, ok := call.Args["limit"].(float64); ok && v > 0 {
		limit = int(v)
	}
	triples := g.rag.Triples(ctx, kb, limit)
	data, _ := json.Marshal(triples)
	return &contract.ToolResult{OK: true, Content: string(data)}
}

// reportRender 把结构化报告（title + sections[{heading,body}]）渲染为真实 .docx，
// 落盘到 contract.ReportPath(task_id)，返回绝对路径供 Gateway 提供下载。
func (g *Gateway) reportRender(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	title, _ := call.Args["title"].(string)
	id, _ := call.Args["task_id"].(string)
	if id == "" {
		id = call.TaskID
	}
	if id == "" {
		return &contract.ToolResult{OK: false, Error: "report_render: task_id 必填"}
	}
	// sections 经 NATS JSON 透传，统一 re-marshal 再解出强类型。
	var secs []office.Section
	if raw, err := json.Marshal(call.Args["sections"]); err == nil {
		_ = json.Unmarshal(raw, &secs)
	}
	data, err := office.NewRenderer().RenderReport(ctx, title, secs)
	if err != nil {
		return &contract.ToolResult{OK: false, Error: "report_render: " + err.Error()}
	}
	path := contract.ReportPath(id)
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return &contract.ToolResult{OK: false, Error: "report_render: mkdir " + err.Error()}
	}
	if err := os.WriteFile(path, data, 0o644); err != nil {
		return &contract.ToolResult{OK: false, Error: "report_render: write " + err.Error()}
	}
	log.Printf("[mcp_go] report_render 已生成 %s (%d 字节, %d 章节)", path, len(data), len(secs))
	return &contract.ToolResult{OK: true, Content: path}
}

// reportSource 是报告的可序列化源数据（标题 + 章节），导出时据此渲染各格式。
type reportSource struct {
	Title    string           `json:"title"`
	Sections []office.Section `json:"sections"`
}

// reportStore 把报告源数据（title + sections）落盘为 JSON，供导出时按需渲染 Word/PDF/Markdown。
// 生成阶段只存源、不渲染（"导出时再处理"）。
func (g *Gateway) reportStore(_ context.Context, call *contract.ToolCall) *contract.ToolResult {
	id, _ := call.Args["task_id"].(string)
	if id == "" {
		id = call.TaskID
	}
	if id == "" {
		return &contract.ToolResult{OK: false, Error: "report_store: task_id 必填"}
	}
	title, _ := call.Args["title"].(string)
	var secs []office.Section
	if raw, err := json.Marshal(call.Args["sections"]); err == nil {
		_ = json.Unmarshal(raw, &secs)
	}
	data, _ := json.Marshal(reportSource{Title: title, Sections: secs})
	path := contract.ReportSourcePath(id)
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return &contract.ToolResult{OK: false, Error: "report_store: mkdir " + err.Error()}
	}
	if err := os.WriteFile(path, data, 0o644); err != nil {
		return &contract.ToolResult{OK: false, Error: "report_store: write " + err.Error()}
	}
	log.Printf("[mcp_go] report_store 已存源 %s (%d 章节)", path, len(secs))
	return &contract.ToolResult{OK: true, Content: path}
}

// reportExport 按需把已存报告源渲染为指定格式：
// docx → 渲染并落盘，返回 .docx 路径；md → 返回 Markdown 文本。
func (g *Gateway) reportExport(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	id, _ := call.Args["task_id"].(string)
	if id == "" {
		id = call.TaskID
	}
	if id == "" {
		return &contract.ToolResult{OK: false, Error: "report_export: task_id 必填"}
	}
	format, _ := call.Args["format"].(string)
	raw, err := os.ReadFile(contract.ReportSourcePath(id))
	if err != nil {
		return &contract.ToolResult{OK: false, Error: "report_export: 报告尚未生成或已过期"}
	}
	var src reportSource
	if err := json.Unmarshal(raw, &src); err != nil {
		return &contract.ToolResult{OK: false, Error: "report_export: 源解析失败"}
	}
	switch format {
	case "md", "markdown":
		return &contract.ToolResult{OK: true, Content: reportMarkdown(src)}
	default: // docx
		data, rerr := office.NewRenderer().RenderReport(ctx, src.Title, src.Sections)
		if rerr != nil {
			return &contract.ToolResult{OK: false, Error: "report_export: " + rerr.Error()}
		}
		path := contract.ReportPath(id)
		if err := os.WriteFile(path, data, 0o644); err != nil {
			return &contract.ToolResult{OK: false, Error: "report_export: write " + err.Error()}
		}
		log.Printf("[mcp_go] report_export 已渲染 docx %s (%d 字节)", path, len(data))
		return &contract.ToolResult{OK: true, Content: path}
	}
}

// reportMarkdown 把报告源拼为 Markdown（标题 + 各章 ## 小标题 + 正文）。
func reportMarkdown(src reportSource) string {
	var b strings.Builder
	if src.Title != "" {
		b.WriteString("# " + src.Title + "\n\n")
	}
	for _, s := range src.Sections {
		if s.Heading != "" {
			b.WriteString("## " + s.Heading + "\n\n")
		}
		b.WriteString(strings.TrimSpace(s.Body) + "\n\n")
	}
	return b.String()
}

// kbIngest 把文本入库（切块→embedding→Milvus+Bleve）。
// 带 job_id 时逐阶段把进度发到 sundynix.streams.<job_id>，供 UI 实时入库监控。
func (g *Gateway) kbIngest(ctx context.Context, call *contract.ToolCall) *contract.ToolResult {
	kb, _ := call.Args["kb"].(string)
	doc, _ := call.Args["doc"].(string)
	text, _ := call.Args["text"].(string)
	jobID, _ := call.Args["job_id"].(string)
	if text == "" {
		return &contract.ToolResult{OK: false, Error: "kb_ingest: text 必填"}
	}
	var onProgress func(contract.IngestEvent)
	if jobID != "" {
		onProgress = func(ev contract.IngestEvent) {
			if data, err := json.Marshal(ev); err == nil {
				_ = g.bus.PublishToken(jobID, data)
			}
		}
	}
	n, err := g.rag.Ingest(ctx, kb, doc, text, onProgress)
	if jobID != "" {
		if err != nil {
			onProgress(contract.IngestEvent{Stage: "失败", Error: err.Error()})
		} else {
			onProgress(contract.IngestEvent{Stage: "完成", Done: n, Total: n, Msg: fmt.Sprintf("已入库 %d 块", n)})
		}
		_ = g.bus.CompleteStream(jobID)
	}
	if err != nil {
		return &contract.ToolResult{OK: false, Error: "kb_ingest: " + err.Error()}
	}
	return &contract.ToolResult{OK: true, Content: fmt.Sprintf("已入库 %d 块到知识库 %q", n, kb)}
}