package handler

// Redis 键扫描(不透明游标分页),设计对标 opsxdb:
//   - 游标 = {pattern, db, type, nodes, index, cursor} 的 base64 编码,服务端校验搜索条件一致
//   - 每页上限 redisKeyPageCap,单页最多 redisScanBatchMax 次 SCAN,整批返回
//   - 集群模式逐 master 分片 SCAN 后归并(ClusterClient.Scan 只命中单节点会漏键)
//   - 无通配符输入:先 TYPE 精确探测(exact 置顶),再按 *关键词* 包含匹配扫描

import (
	"context"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"net/http"
	"sort"
	"strconv"
	"strings"
	"time"

	"sql-platform/internal/handler/resp"
	"sql-platform/internal/model"

	"github.com/gin-gonic/gin"
	"github.com/redis/go-redis/v9"
)

const (
	redisKeyPageCap    = 200 // 每页最多返回的 key 数
	redisScanBatchMax  = 20  // 单页最多 SCAN 调用次数(凑满一页即提前返回)
	redisScanCountHint = 100 // SCAN COUNT 提示值
)

// RedisScanKeyInfo 单个键摘要(TTL 毫秒,-1 永久;与既有前端契约一致)
type RedisScanKeyInfo struct {
	Key  string `json:"key"`
	Type string `json:"type"`
	TTL  int64  `json:"ttl"`
}

// keyScanPosition 不透明游标内容:记录搜索条件与扫描位置
type keyScanPosition struct {
	Pattern string   `json:"pattern"`
	DB      int      `json:"db"`
	Type    string   `json:"type,omitempty"`
	Nodes   []string `json:"nodes"` // 集群:各 master 地址(排序);单机:单地址
	Index   int      `json:"index"` // 当前扫描的节点下标
	Cursor  uint64   `json:"cursor"`
}

func encodeScanPosition(p keyScanPosition) string {
	b, _ := json.Marshal(p)
	return base64.RawURLEncoding.EncodeToString(b)
}

func decodeScanPosition(s string) (keyScanPosition, error) {
	var p keyScanPosition
	b, err := base64.RawURLEncoding.DecodeString(strings.TrimSpace(s))
	if err != nil {
		return p, fmt.Errorf("无效的游标")
	}
	if err := json.Unmarshal(b, &p); err != nil {
		return p, fmt.Errorf("无效的游标")
	}
	return p, nil
}

// redisBrowsePattern 模式规则:无通配符自动包 *关键词*(包含匹配);有则按 glob 原样
func redisBrowsePattern(raw string) string {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return "*"
	}
	if strings.ContainsAny(raw, "*?[") {
		return raw
	}
	return "*" + raw + "*"
}

func ttlMilliseconds(d time.Duration) int64 {
	if d > 0 {
		return d.Milliseconds()
	}
	return -1
}

// redisMovedHint 单机模式收到 MOVED 时提示切换部署模式(opsxdb 同款)
func redisErrHint(err error) error {
	if err == nil {
		return nil
	}
	msg := err.Error()
	if strings.Contains(msg, "MOVED") {
		return fmt.Errorf("%w;该键已被集群分片管理,请把实例的部署模式改为集群并填写种子节点", err)
	}
	return err
}

// scanStandaloneNode 用独立连接扫描单个节点(集群分片 SCAN 必须直连 master)
func scanStandaloneNode(ctx context.Context, w *redisClientWrapper, addr string, cursor uint64, match string, callBudget, softCap int) (keys []string, nextCursor uint64, calls int, err error) {
	var client *redis.Client
	if !w.IsCluster() || len(w.MasterAddrs) == 1 && addr == w.MasterAddrs[0] && w.Client != nil {
		client = w.Client // 单机直接复用主连接
	} else {
		client = redis.NewClient(&redis.Options{
			Addr:         addr,
			Username:     w.Username,
			Password:     w.Password,
			DB:           0, // 集群恒 DB0
			DialTimeout:  5 * time.Second,
			ReadTimeout:  5 * time.Second,
			WriteTimeout: 5 * time.Second,
		})
		defer client.Close()
	}
	for calls < callBudget && len(keys) < softCap {
		var batch []string
		batch, nextCursor, err = client.Scan(ctx, cursor, match, redisScanCountHint).Result()
		if err != nil {
			return nil, 0, calls, err
		}
		keys = append(keys, batch...)
		calls++
		cursor = nextCursor
		if nextCursor == 0 {
			break // 该节点扫描完毕
		}
	}
	return keys, cursor, calls, nil
}

// pipelineTypeTTL 批量取 TYPE/TTL,替换逐 key 串行 N+1
func pipelineTypeTTL(ctx context.Context, w *redisClientWrapper, keys []string) (types map[string]string, ttls map[string]int64) {
	types = make(map[string]string, len(keys))
	ttls = make(map[string]int64, len(keys))
	if len(keys) == 0 {
		return
	}
	var pipe redis.Pipeliner
	if w.IsCluster() && w.ClusterClient != nil {
		pipe = w.ClusterClient.Pipeline()
	} else {
		pipe = w.Client.Pipeline()
	}
	typeCmds := make([]*redis.StatusCmd, len(keys))
	ttlCmds := make([]*redis.DurationCmd, len(keys))
	for i, k := range keys {
		typeCmds[i] = pipe.Type(ctx, k)
		ttlCmds[i] = pipe.TTL(ctx, k)
	}
	_, _ = pipe.Exec(ctx)
	for i, k := range keys {
		t, err := typeCmds[i].Result()
		if err != nil {
			t = "none"
		}
		types[k] = t
		ttls[k] = ttlMilliseconds(ttlCmds[i].Val())
	}
	return
}

// GET /api/v1/redis/:id/keys — 游标分页扫描
func RedisScanKeysPaged(c *gin.Context) {
	id := c.Param("id")
	db := 0
	if v := c.Query("db"); v != "" {
		db, _ = strconv.Atoi(v)
	}
	rawPattern := strings.TrimSpace(c.Query("pattern"))
	reqType := strings.TrimSpace(c.Query("type"))
	cursorParam := strings.TrimSpace(c.Query("cursor"))

	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		resp.NotFound(c, "Instance not found")
		return
	}

	// 集群只允许 DB0
	if instance.ClusterMode != nil && *instance.ClusterMode {
		db = 0
	}

	client, err := getRedisClient(&instance, db)
	if err != nil {
		resp.InternalErr(c, err)
		return
	}
	defer client.Close()

	ctx, cancel := context.WithTimeout(context.Background(), 8*time.Second)
	defer cancel()

	pattern := redisBrowsePattern(rawPattern)

	// 精确命中探测:无通配符且非全量时,先 TYPE 直查(集群走槽位路由,不受 NAT 影响)
	var exact *RedisScanKeyInfo
	rawHasWildcard := strings.ContainsAny(rawPattern, "*?[")
	if rawPattern != "" && rawPattern != "*" && !rawHasWildcard {
		if keyType, err := client.Type(ctx, rawPattern).Result(); err == nil && keyType != "none" {
			ttl, _ := client.TTL(ctx, rawPattern).Result()
			exact = &RedisScanKeyInfo{Key: rawPattern, Type: keyType, TTL: ttlMilliseconds(ttl)}
		}
	}

	// 还原或初始化游标
	var pos keyScanPosition
	if cursorParam != "" {
		pos, err = decodeScanPosition(cursorParam)
		if err != nil {
			resp.BadRequest(c, err.Error())
			return
		}
		if pos.Pattern != pattern || pos.DB != db || pos.Type != reqType || !equalStrings(pos.Nodes, client.MasterAddrs) {
			resp.BadRequest(c, "搜索条件已变化,请重新搜索")
			return
		}
	} else {
		pos = keyScanPosition{Pattern: pattern, DB: db, Type: reqType, Nodes: client.MasterAddrs, Index: 0, Cursor: 0}
	}

	// 逐节点增量扫描,凑满一页即返回
	nameSet := map[string]bool{}
	budget := redisScanBatchMax
	for pos.Index < len(pos.Nodes) && budget > 0 && len(nameSet) < redisKeyPageCap {
		batch, nextCursor, calls, err := scanStandaloneNode(ctx, client, pos.Nodes[pos.Index], pos.Cursor, pattern, budget, redisKeyPageCap-len(nameSet))
		if err != nil {
			resp.BadRequest(c, redisErrHint(err).Error())
			return
		}
		budget -= calls
		for _, k := range batch {
			nameSet[k] = true
		}
		pos.Cursor = nextCursor
		if nextCursor == 0 {
			pos.Index++ // 该节点扫完,移到下一分片
			pos.Cursor = 0
		}
	}

	names := make([]string, 0, len(nameSet))
	for k := range nameSet {
		names = append(names, k)
	}
	sort.Strings(names)

	types, ttls := pipelineTypeTTL(ctx, client, names)
	keys := make([]RedisScanKeyInfo, 0, len(names))
	for _, k := range names {
		t := types[k]
		if reqType != "" && t != reqType {
			continue
		}
		if t == "none" {
			continue // 扫描与 TYPE 之间已过期
		}
		keys = append(keys, RedisScanKeyInfo{Key: k, Type: t, TTL: ttls[k]})
	}

	// 所有节点扫完前都可继续翻页(SCAN 次数用尽同样可续)
	nextCursor := ""
	if pos.Index < len(pos.Nodes) {
		nextCursor = encodeScanPosition(pos)
	}

	c.JSON(http.StatusOK, gin.H{
		"keys":        keys,
		"next_cursor": nextCursor,
		"exact":       exact,
		"total":       len(keys),
		"cluster":     client.IsCluster(),
	})
}

// GET /api/v1/redis/:id/dbs — 库列表(集群恒 [0])
func RedisDbs(c *gin.Context) {
	id := c.Param("id")
	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		resp.NotFound(c, "Instance not found")
		return
	}

	isCluster := instance.ClusterMode != nil && *instance.ClusterMode
	if !isCluster {
		client, err := getRedisClient(&instance, 0)
		if err != nil {
			resp.InternalErr(c, err)
			return
		}
		defer client.Close()
		isCluster = client.IsCluster()
	}

	dbs := []int{0}
	if !isCluster {
		for i := 1; i <= 15; i++ {
			dbs = append(dbs, i)
		}
	}
	c.JSON(http.StatusOK, gin.H{"dbs": dbs, "cluster": isCluster})
}

// POST /api/v1/redis/:id/keys/:key/field — Hash 行级编辑(HSET/HDEL,不整键重写)
func RedisUpdateKeyField(c *gin.Context) {
	id := c.Param("id")
	key := c.Param("key")
	db := 0
	if v := c.Query("db"); v != "" {
		db, _ = strconv.Atoi(v)
	}

	var input struct {
		Op    string `json:"op" binding:"required"` // set | del
		Field string `json:"field" binding:"required"`
		Value string `json:"value"`
	}
	if err := c.ShouldBindJSON(&input); err != nil {
		resp.BadRequest(c, err.Error())
		return
	}
	if input.Op != "set" && input.Op != "del" {
		resp.BadRequest(c, "op 仅支持 set / del")
		return
	}

	var instance model.Instance
	if err := model.DB.First(&instance, id).Error; err != nil {
		resp.NotFound(c, "Instance not found")
		return
	}

	client, err := getRedisClient(&instance, db)
	if err != nil {
		resp.InternalErr(c, err)
		return
	}
	defer client.Close()

	ctx := context.Background()
	if keyType, err := client.Type(ctx, key).Result(); err != nil || keyType != "hash" {
		resp.BadRequest(c, "仅支持 Hash 类型键的行级编辑")
		return
	}

	if input.Op == "del" {
		if err := client.HDel(ctx, key, input.Field).Err(); err != nil {
			resp.InternalErr(c, err)
			return
		}
	} else {
		if err := client.HSet(ctx, key, input.Field, input.Value).Err(); err != nil {
			resp.InternalErr(c, err)
			return
		}
	}
	resp.Message(c, "Field updated")
}

func equalStrings(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}