// Package agv 海康 AGV 调度系统(RCS-2000 V4.2) 对接客户端。
// 能力：下发搬运任务(task/submit)、查询任务状态(task/query)。
// 签名协议详见《AGV海康.md》：HMAC-SHA256 加盐 + MD5 二次摘要，sign 放 URL query。
// 未配置真实 RCS(appKey/appSecret/BaseURL) 或 EnableMock=true 时走 Mock 客户端。
package agv

import (
	"bytes"
	"context"
	"crypto/hmac"
	"crypto/md5"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"sort"
	"strings"
	"time"

	"bj_power_wms/internal/config"
)

// Client AGV 调度客户端抽象
type Client interface {
	// SubmitTask 下发搬运任务 fromDock -> toDock，返回海康任务号 robotTaskCode。
	SubmitTask(ctx context.Context, fromDock, toDock, carrierCode string) (string, error)
	// QueryTask 查询任务状态，返回海康 taskStatus 枚举。
	QueryTask(ctx context.Context, robotTaskCode string) (string, error)
}

// New 依据配置返回真实或 Mock 客户端
func New(cfg config.AgvConfig) Client {
	if cfg.EnableMock || cfg.BaseURL == "" {
		return newMockClient()
	}
	return newRealClient(cfg)
}

// ---------- 签名与请求（真实海康） ----------

type realClient struct {
	cfg      config.AgvConfig
	hc       *http.Client
	carrier  string
}

func newRealClient(cfg config.AgvConfig) *realClient {
	return &realClient{
		cfg:     cfg,
		hc:      &http.Client{Timeout: 15 * time.Second},
		carrier: cfg.CarrierCode,
	}
}

// buildPath 拼接服务前缀 + 业务路径，system
func (c *realClient) url(path string) string {
	base := strings.TrimRight(c.cfg.BaseURL, "/")
	return base + path
}

// submit 任务下发实现的实际请求
// 海康路径：/rcs/rtas/api/robot/controller/task/submit
func (c *realClient) post(ctx context.Context, path string, payload map[string]any, out any) error {
	body, err := json.Marshal(payload)
	if err != nil {
		return err
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, c.url(path), bytes.NewReader(body))
	if err != nil {
		return err
	}
	c.sign(req, body, path)
	resp, err := c.hc.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	raw, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	if resp.StatusCode >= 400 {
		return fmt.Errorf("agv http %d: %s", resp.StatusCode, string(raw))
	}
	var envelope struct {
		Code    string          `json:"code"`
		Message string          `json:"message"`
		Data    json.RawMessage `json:"data"`
	}
	if err := json.Unmarshal(raw, &envelope); err != nil {
		return fmt.Errorf("agv parse envelope: %w", err)
	}
	if envelope.Code != "" && envelope.Code != "SUCCESS" {
		return fmt.Errorf("agv code=%s message=%s", envelope.Code, envelope.Message)
	}
	if out != nil && len(envelope.Data) > 0 {
		return json.Unmarshal(envelope.Data, out)
	}
	return nil
}

// sign 按协议 1.3 节生成鉴权头与 sign 签名。
// 参与签名字段（排序）：AUTHORIZATION、HOST、X-LR-APPKEY、X-LR-REQUEST-ID、X-LR-SOURCE、X-LR-TRACE-ID、X-LR-VERSION
// 签名 = MD5( HMAC-SHA256(appSecret, 拼接原串) )，sign 作为 URL query 参数。
func (c *realClient) sign(req *http.Request, body []byte, path string) {
	nonce := randHex(8)
	timestamp := time.Now().Format(time.RFC3339)
	requestID := randHex(16)
	traceID := randHex(16)

	authHeader := fmt.Sprintf("nonce=%q,method=\"HMAC-SHA256\",timestamp=%q", nonce, timestamp)
	signKV := map[string]string{
		"AUTHORIZATION":   authHeader,
		"HOST":            req.URL.Host,
		"X-LR-APPKEY":     c.cfg.AppKey,
		"X-LR-REQUEST-ID": requestID,
		"X-LR-SOURCE":     "bj_power_wms",
		"X-LR-TRACE-ID":   traceID,
		"X-LR-VERSION":    "v1.0",
	}
	keys := make([]string, 0, len(signKV))
	for k := range signKV {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	var sb strings.Builder
	for _, k := range keys {
		sb.WriteString(k)
		sb.WriteString(":")
		sb.WriteString(signKV[k])
		sb.WriteString("\n")
	}
	// 请求报文拼接后的原串 = 头拼接串 + 空行 + 消息体
	raw := sb.String() + "\n" + string(body)
	mac := hmac.New(sha256.New, []byte(c.cfg.AppSecret))
	mac.Write([]byte(raw))
	h := md5.Sum(mac.Sum(nil))
	sign := strings.ToUpper(hex.EncodeToString(h[:]))

	q := req.URL.Query()
	q.Set("sign", sign)
	req.URL.RawQuery = q.Encode()

	req.Header.Set("Authorization", authHeader)
	req.Header.Set("X-lr-appkey", c.cfg.AppKey)
	req.Header.Set("X-lr-request-id", requestID)
	req.Header.Set("X-lr-version", "v1.0")
	req.Header.Set("X-lr-trace-id", traceID)
	req.Header.Set("X-lr-source", "bj_power_wms")
}

// SubmitTask 实现 Client：下发搬运任务。
// 海康路径 /rcs/rtas/api/robot/controller/task/submit
func (c *realClient) SubmitTask(ctx context.Context, fromDock, toDock, carrierCode string) (string, error) {
	carrier := carrierCode
	if carrier == "" {
		carrier = c.carrier
	}
	payload := map[string]any{
		"taskType": "PF-LMR-COMMON",
		"targetRoute": []map[string]any{
			{"type": "SITE", "code": fromDock, "operation": "COLLECT"},
			{"type": "SITE", "code": toDock, "operation": "DELIVERY"},
		},
		"carrierInfo": []map[string]any{
			{"carrierType": "1", "carrierCode": carrier},
		},
	}
	var data struct {
		RobotTaskCode string `json:"robotTaskCode"`
		Code          string `json:"code"`
	}
	if err := c.post(ctx, "/api/robot/controller/task/submit", payload, &data); err != nil {
		return "", err
	}
	if data.RobotTaskCode == "" {
		// 部分版本把任务号放 data.code
		if data.Code == "" {
			return "", fmt.Errorf("agv submit 未返回任务号")
		}
		return data.Code, nil
	}
	return data.RobotTaskCode, nil
}

// QueryTask 实现 Client：查询任务状态。
// 海康路径 /rcs/rtas/api/robot/controller/task/query
func (c *realClient) QueryTask(ctx context.Context, robotTaskCode string) (string, error) {
	payload := map[string]any{"robotTaskCode": robotTaskCode}
	var data map[string]any
	if err := c.post(ctx, "/api/robot/controller/task/query", payload, &data); err != nil {
		return "", err
	}
	st, _ := data["taskStatus"].(string)
	if st == "" {
		if v, ok := data["status"].(string); ok {
			st = v
		}
	}
	if st == "" {
		return "QUEUE", nil
	}
	return st, nil
}

// ---------- Mock 客户端（未接真实 RCS 时用） ----------

type mockClient struct{}

func newMockClient() *mockClient { return &mockClient{} }

func (m *mockClient) SubmitTask(ctx context.Context, fromDock, toDock, carrierCode string) (string, error) {
	// 模拟立即成功下发，返回一个可追溯的假任务号（前缀 MOCK-）
	return "MOCK-" + randHex(8), nil
}

func (m *mockClient) QueryTask(ctx context.Context, robotTaskCode string) (string, error) {
	// 模拟：MOCK 任务一律视为已完成，便于离线联调观察"待搬运→已到位"。
	return "FINISHED", nil
}

func randHex(n int) string {
	b := make([]byte, n)
	if _, err := rand.Read(b); err != nil {
		return fmt.Sprintf("%02d", time.Now().UnixNano()%100)
	}
	return hex.EncodeToString(b)
}