// latencyprobe：12B 延迟验收工具——走本地网关全链路（WS 网关 → gummy）实测延迟分布。
//
// 复刻桌面客户端行为：单条持久 WS 连接，串行多次会话，音频实时推流（100ms/帧）。
//
// 测量口径对齐桌面端 dictation.rs：
//
//	first_partial_ms     = start 帧发出 → 本会话首个 partial 收到
//	                       （桌面端另含麦克风启动耗时 audio.start_ms，此处不含）
//	release_to_commit_ms = stop 帧发出 → 本会话尾部 final 收到（文本完整落定）
//	                       （桌面端另含文字注入耗时，通常 <10ms，此处不含；
//	                        若 stop 后先到 usage 帧，桌面端会提前以 partial 文本注入，
//	                        该情形单独计数为 usage_first）
//
// 用法（服务端需已以 gummy provider 启动）：
//
//	go run ./cmd/latencyprobe -wav /path/to/16k-mono-16bit.wav -n 12
package main

import (
	"encoding/binary"
	"encoding/json"
	"flag"
	"fmt"
	"net/http"
	"os"
	"sort"
	"time"

	"github.com/gorilla/websocket"

	"dudu/server/internal/auth"
	"dudu/server/internal/store"
	"dudu/server/pkg/protocol"
)

type event struct {
	msg protocol.ServerMsg
	at  time.Time
}

func main() {
	addr := flag.String("addr", "localhost:8080", "服务端地址")
	wavPath := flag.String("wav", "", "16kHz/16bit/mono wav 文件路径")
	n := flag.Int("n", 12, "会话次数（注意 30 分钟滑动窗口上限 30 次/设备）")
	dsn := flag.String("dsn", "host=localhost user=dudu password=dudu dbname=dudu port=5432 sslmode=disable TimeZone=Asia/Shanghai", "postgres dsn（用于确保探针用户存在且余额充足）")
	secret := flag.String("secret", "dev-secret-change-me", "JWT secret（须与服务端一致）")
	userID := flag.String("user", "latency-probe", "探针用户 ID")
	deviceID := flag.String("device", "probe-dev", "探针设备 ID")
	flag.Parse()
	if *wavPath == "" {
		fmt.Fprintln(os.Stderr, "用法: latencyprobe -wav test.wav [-n 12]")
		os.Exit(2)
	}

	pcm, err := readWavData(*wavPath)
	if err != nil {
		fmt.Fprintln(os.Stderr, "读 wav 失败:", err)
		os.Exit(1)
	}
	audioSec := float64(len(pcm)) / float64(protocol.SampleRate*2)
	fmt.Printf("音频 %.1fs · %d 次会话 · 单连接串行 · 实时推流（100ms/帧）\n", audioSec, *n)

	// 确保探针用户存在且余额充足（试用 180s/天 不够跑长测）。
	db, err := store.Open(*dsn)
	if err != nil {
		fmt.Fprintln(os.Stderr, "postgres 连接失败:", err)
		os.Exit(1)
	}
	var u store.User
	db.Where(store.User{ID: *userID}).FirstOrCreate(&u)
	if err := db.Model(&store.User{}).Where("id = ?", *userID).Update("balance_seconds", 360000).Error; err != nil {
		fmt.Fprintln(os.Stderr, "更新探针用户余额失败:", err)
		os.Exit(1)
	}

	token, err := auth.NewJWT(*secret, time.Hour, nil).Sign(*userID)
	if err != nil {
		fmt.Fprintln(os.Stderr, "签发 JWT 失败:", err)
		os.Exit(1)
	}

	// 单条持久连接（桌面端同款）：会话串行复用，读循环常驻。
	url := fmt.Sprintf("ws://%s/v1/asr/stream?device_id=%s", *addr, *deviceID)
	hdr := http.Header{"Authorization": {"Bearer " + token}}
	conn, _, err := websocket.DefaultDialer.Dial(url, hdr)
	if err != nil {
		fmt.Fprintln(os.Stderr, "dial 失败:", err)
		os.Exit(1)
	}
	defer conn.Close()
	events := make(chan event, 256)
	go func() {
		defer close(events)
		for {
			var msg protocol.ServerMsg
			if err := conn.ReadJSON(&msg); err != nil {
				return
			}
			events <- event{msg, time.Now()}
		}
	}()

	var firstPartials, releaseToCommits []time.Duration
	usageFirst := 0
	for i := 0; i < *n; i++ {
		sid := fmt.Sprintf("probe-%d-%d", time.Now().UnixNano(), i)
		r, err := runSession(conn, events, sid, pcm)
		if err != nil {
			fmt.Printf("  #%02d 失败: %v\n", i+1, err)
		} else {
			firstPartials = append(firstPartials, r.firstPartial)
			releaseToCommits = append(releaseToCommits, r.releaseToCommit)
			note := ""
			if r.usageBeforeFinal {
				usageFirst++
				note = "  ⚠️usage先到"
			}
			fmt.Printf("  #%02d first_partial=%5dms  release_to_commit=%4dms  %q%s\n",
				i+1, r.firstPartial.Milliseconds(), r.releaseToCommit.Milliseconds(), truncate(r.text, 24), note)
		}
		time.Sleep(800 * time.Millisecond) // 会话间隔（无论成败），模拟自然停顿
	}

	if len(firstPartials) == 0 {
		fmt.Fprintln(os.Stderr, "无有效样本")
		os.Exit(1)
	}
	fmt.Println()
	report("first_partial     ", firstPartials, 500*time.Millisecond)
	report("release_to_commit ", releaseToCommits, 300*time.Millisecond)
	if usageFirst > 0 {
		fmt.Printf("⚠️ %d/%d 次会话 stop 后 usage 帧先于尾部 final 到达（桌面端将以 partial 文本提前注入，丢失 final 修正）\n",
			usageFirst, len(firstPartials))
	}
}

type sessionResult struct {
	firstPartial     time.Duration
	releaseToCommit  time.Duration
	text             string
	usageBeforeFinal bool
}

// runSession 在共享连接上执行一次会话：start → 实时推流 → stop → 等尾部 final。
// 事件按 session_id 过滤，前一会话的迟到帧不串扰。
func runSession(conn *websocket.Conn, events <-chan event, sid string, pcm []byte) (r sessionResult, err error) {
	start, _ := json.Marshal(protocol.ClientMsg{Type: protocol.MsgStart, SessionID: sid, SampleRate: protocol.SampleRate, Format: "pcm16"})
	t0 := time.Now()
	if err := conn.WriteMessage(websocket.TextMessage, start); err != nil {
		return r, fmt.Errorf("start: %w", err)
	}

	handle := func(ev event, tStop *time.Time) error {
		if ev.msg.SessionID != sid {
			return nil // 旧会话迟到帧
		}
		switch ev.msg.Type {
		case protocol.MsgPartial:
			if r.firstPartial == 0 {
				r.firstPartial = ev.at.Sub(t0)
			}
		case protocol.MsgFinal:
			r.text += ev.msg.Text
			if tStop != nil && r.releaseToCommit == 0 {
				r.releaseToCommit = ev.at.Sub(*tStop)
			}
		case protocol.MsgUsage:
			if tStop != nil && r.releaseToCommit == 0 {
				r.usageBeforeFinal = true // 桌面端此刻已提前注入 partial 文本
			}
		case protocol.MsgError:
			return fmt.Errorf("server error: %s %s", ev.msg.Code, ev.msg.Message)
		}
		return nil
	}

	// 实时推流 + 并行收包。
	ticker := time.NewTicker(protocol.FrameMillis * time.Millisecond)
	defer ticker.Stop()
	off := 0
	for off < len(pcm) {
		select {
		case <-ticker.C:
			end := min(off+protocol.FrameBytes, len(pcm))
			if err := conn.WriteMessage(websocket.BinaryMessage, pcm[off:end]); err != nil {
				return r, fmt.Errorf("audio: %w", err)
			}
			off = end
		case ev, ok := <-events:
			if !ok {
				return r, fmt.Errorf("连接已断开")
			}
			if err := handle(ev, nil); err != nil {
				return r, err
			}
		}
	}

	stop, _ := json.Marshal(protocol.ClientMsg{Type: protocol.MsgStop, SessionID: sid})
	tStop := time.Now()
	if err := conn.WriteMessage(websocket.TextMessage, stop); err != nil {
		return r, fmt.Errorf("stop: %w", err)
	}

	// 收尾：等尾部 final（文本完整落定），10s 兜底。
	deadline := time.After(10 * time.Second)
	for r.releaseToCommit == 0 {
		select {
		case ev, ok := <-events:
			if !ok {
				return r, fmt.Errorf("连接已断开")
			}
			if err := handle(ev, &tStop); err != nil {
				return r, err
			}
		case <-deadline:
			return r, fmt.Errorf("收尾超时：stop 后 10s 未收到尾部 final")
		}
	}
	if r.firstPartial == 0 {
		return r, fmt.Errorf("全程未收到 partial")
	}
	return r, nil
}

func report(name string, ds []time.Duration, target time.Duration) {
	sorted := append([]time.Duration(nil), ds...)
	sort.Slice(sorted, func(i, j int) bool { return sorted[i] < sorted[j] })
	p50 := sorted[len(sorted)/2]
	p95 := sorted[(len(sorted)*95+99)/100-1]
	verdict := "✅ 达标"
	if p95 > target {
		verdict = "❌ 超标"
	}
	fmt.Printf("%s n=%d  P50=%dms  P95=%dms  min=%dms  max=%dms  目标P95<%dms  %s\n",
		name, len(sorted), p50.Milliseconds(), p95.Milliseconds(),
		sorted[0].Milliseconds(), sorted[len(sorted)-1].Milliseconds(), target.Milliseconds(), verdict)
}

func truncate(s string, n int) string {
	r := []rune(s)
	if len(r) <= n {
		return s
	}
	return string(r[:n]) + "…"
}

// readWavData 提取 wav 的 data chunk（仅支持 PCM，同 gummycheck）。
func readWavData(path string) ([]byte, error) {
	b, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	if len(b) < 44 || string(b[0:4]) != "RIFF" || string(b[8:12]) != "WAVE" {
		return nil, fmt.Errorf("不是 wav 文件")
	}
	off := 12
	for off+8 <= len(b) {
		id := string(b[off : off+4])
		size := int(binary.LittleEndian.Uint32(b[off+4 : off+8]))
		if id == "data" {
			return b[off+8 : min(off+8+size, len(b))], nil
		}
		off += 8 + size
	}
	return nil, fmt.Errorf("未找到 data chunk")
}