package handler

import (
	"encoding/json"
	"log"
	"net/http"
	"strings"
	"time"

	"aijianzhan/platform/internal/audit"
	"aijianzhan/platform/internal/authx"
	"aijianzhan/platform/internal/dbsync"
	"aijianzhan/platform/internal/svc"

	"github.com/zeromicro/go-zero/rest/httpx"
	"github.com/zeromicro/go-zero/rest/pathvar"
)

// agent 同步：管理员/智能体（「数据同步」）租户级；普通登录用户按本人 Binding 范围。

func agentSyncWhitelistHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		if !requireDBSync(svcCtx, w) {
			return
		}
		channelID := pathvar.Vars(r)["id"]
		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
		if err != nil {
			authx.WriteError(w, http.StatusNotFound, err.Error())
			return
		}
		if !authorizeUserSyncChannel(svcCtx, w, r, channelID) {
			return
		}
		tables := uniqueStringSlice(ch.Local.Tables, ch.Remote.Tables)
		hint := "通道 tables 仅历史兼容；用户自助以 Binding+JWT 为权限，整库表均可 push（可不改白名单）"
		if len(tables) == 0 {
			hint = "通道表白名单为空；以 Binding 为准，接受任意表 push（可自动建表）"
		}
		httpx.OkJson(w, map[string]any{
			"channel_id":      ch.ID,
			"name":            ch.Name,
			"enabled":         ch.Enabled,
			"direction":       ch.Direction,
			"conflict_policy": ch.ConflictPolicy,
			"tables":          tables,
			"pk_columns":      ch.PKColumns,
			"hint":            hint,
		})
	}
}

func agentSyncPushHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		started := time.Now()
		reqID := r.Header.Get("X-Request-Id")
		if !requireDBSync(svcCtx, w) {
			return
		}
		channelID := pathvar.Vars(r)["id"]
		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
		if err != nil {
			authx.WriteError(w, http.StatusNotFound, err.Error())
			return
		}
		var item dbsync.PushItem
		if err := json.NewDecoder(r.Body).Decode(&item); err != nil {
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		if !authorizeUserSyncPush(svcCtx, w, r, channelID, item) {
			return
		}
		res, err := dbsync.PushToRemote(r.Context(), ch, svcCtx.DBSync.Store(), item)
		dur := time.Since(started)
		if err != nil {
			logSyncReq(r, "push", channelID, item.Table, item.RowPK, "err", err.Error(), dur, reqID)
			auditSync(svcCtx, r, "dbsync.push.error", map[string]any{
				"channel_id": channelID, "table": item.Table, "row_pk": item.RowPK,
				"online_db_id": item.OnlineDBID, "error": err.Error(), "ms": dur.Milliseconds(), "req_id": reqID,
			})
			if dbsync.IsRetryable(err) {
				authx.WriteRetryableError(w, http.StatusServiceUnavailable, err.Error())
				return
			}
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		outcome := "applied"
		if res != nil && res.Skipped {
			outcome = "skipped"
		}
		logSyncReq(r, "push", channelID, item.Table, item.RowPK, outcome, "", dur, reqID)
		auditSync(svcCtx, r, "dbsync.push", map[string]any{
			"channel_id": channelID, "table": item.Table, "row_pk": item.RowPK,
			"online_db_id": item.OnlineDBID, "outcome": outcome, "ms": dur.Milliseconds(), "req_id": reqID,
		})
		httpx.OkJson(w, map[string]any{"success": true, "result": res})
	}
}

func agentSyncPushBatchHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		started := time.Now()
		reqID := r.Header.Get("X-Request-Id")
		if !requireDBSync(svcCtx, w) {
			return
		}
		channelID := pathvar.Vars(r)["id"]
		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
		if err != nil {
			authx.WriteError(w, http.StatusNotFound, err.Error())
			return
		}
		var body struct {
			Items []dbsync.PushItem `json:"items"`
		}
		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		if len(body.Items) == 0 {
			authx.WriteError(w, http.StatusBadRequest, "items required")
			return
		}
		if len(body.Items) > 100 {
			authx.WriteError(w, http.StatusBadRequest, "items limit 100")
			return
		}
		for _, item := range body.Items {
			if !authorizeUserSyncPush(svcCtx, w, r, channelID, item) {
				return
			}
		}
		results, err := dbsync.PushBatchToRemote(r.Context(), ch, svcCtx.DBSync.Store(), body.Items)
		dur := time.Since(started)
		if err != nil {
			logSyncReq(r, "push_batch", channelID, "", "", "err", err.Error(), dur, reqID)
			auditSync(svcCtx, r, "dbsync.push_batch.error", map[string]any{
				"channel_id": channelID, "n": len(body.Items), "error": err.Error(),
				"ms": dur.Milliseconds(), "req_id": reqID,
			})
			payload := map[string]any{
				"success": false,
				"error":   err.Error(),
				"results": results,
			}
			if dbsync.IsRetryable(err) {
				payload["retryable"] = true
				httpx.WriteJson(w, http.StatusServiceUnavailable, payload)
				return
			}
			httpx.OkJson(w, payload)
			return
		}
		logSyncReq(r, "push_batch", channelID, "", "", "ok", "", dur, reqID)
		auditSync(svcCtx, r, "dbsync.push_batch", map[string]any{
			"channel_id": channelID, "n": len(body.Items), "ms": dur.Milliseconds(), "req_id": reqID,
		})
		httpx.OkJson(w, map[string]any{"success": true, "results": results})
	}
}

func logSyncReq(r *http.Request, op, channelID, table, rowPK, outcome, errMsg string, dur time.Duration, reqID string) {
	uid := authx.UserID(r.Context())
	if errMsg != "" {
		log.Printf("dbsync %s channel=%s table=%s pk=%s user=%d outcome=%s err=%s dur=%s req=%s",
			op, channelID, table, rowPK, uid, outcome, errMsg, dur, reqID)
		return
	}
	log.Printf("dbsync %s channel=%s table=%s pk=%s user=%d outcome=%s dur=%s req=%s",
		op, channelID, table, rowPK, uid, outcome, dur, reqID)
}

func auditSync(svcCtx *svc.ServiceContext, r *http.Request, action string, detail map[string]any) {
	if svcCtx == nil || svcCtx.Audit == nil {
		return
	}
	_ = svcCtx.Audit.Log(r.Context(), syncTenantID(r), authx.UserID(r.Context()), action, audit.DetailJSON(detail))
}

// authorizeUserSyncChannel 无「数据同步」时，须本人 Binding 覆盖该通道。
func authorizeUserSyncChannel(svcCtx *svc.ServiceContext, w http.ResponseWriter, r *http.Request, channelID string) bool {
	if authx.SyncTenantWide(r.Context()) {
		return true
	}
	uid := authx.UserID(r.Context())
	tid := syncTenantID(r)
	if !svcCtx.DBSync.Store().UserCanAccessChannel(tid, uid, channelID) {
		authx.WriteError(w, http.StatusForbidden, "无权访问该同步通道：请先登记本人 Binding（local_database_id ↔ online_db_id + channel_id）")
		return false
	}
	return true
}

// authorizeUserSyncPush 无「数据同步」时，须本人 Binding 且 online_db_id 匹配。
func authorizeUserSyncPush(svcCtx *svc.ServiceContext, w http.ResponseWriter, r *http.Request, channelID string, item dbsync.PushItem) bool {
	return authorizeUserOnlineDB(svcCtx, w, r, channelID, item.OnlineDBID, "用户自助 push 须带 online_db_id，且须为本人 Binding")
}

// authorizeUserOnlineDB：带 online_db_id 时一律按本人 Binding 校验（含有「数据同步」的人类管理员）。
// 仅「数据同步」且未带 online_db_id 时保持租户级管理路径（智能体/管理员兼容）。
func authorizeUserOnlineDB(svcCtx *svc.ServiceContext, w http.ResponseWriter, r *http.Request, channelID, onlineDBID, emptyMsg string) bool {
	online := strings.TrimSpace(onlineDBID)
	wide := authx.SyncTenantWide(r.Context())
	if online == "" {
		if wide {
			return true
		}
		if emptyMsg == "" {
			emptyMsg = "用户自助须带 online_db_id，且须为本人 Binding"
		}
		authx.WriteError(w, http.StatusForbidden, emptyMsg)
		return false
	}
	uid := authx.UserID(r.Context())
	tid := syncTenantID(r)
	if !svcCtx.DBSync.Store().UserOwnsOnlineDB(tid, uid, channelID, online) {
		authx.WriteError(w, http.StatusForbidden, "无权访问该 online_db_id（非本人 Binding / 非公司共享库）")
		return false
	}
	return true
}

func agentSyncPullHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return agentSyncPullWithDefaultMode(svcCtx, "")
}

func agentSyncBootstrapHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return agentSyncPullWithDefaultMode(svcCtx, dbsync.PullModeBootstrap)
}

func agentSyncPullWithDefaultMode(svcCtx *svc.ServiceContext, forceMode string) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		started := time.Now()
		reqID := r.Header.Get("X-Request-Id")
		if !requireDBSync(svcCtx, w) {
			return
		}
		channelID := pathvar.Vars(r)["id"]
		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
		if err != nil {
			authx.WriteError(w, http.StatusNotFound, err.Error())
			return
		}
		var req dbsync.PullRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		if forceMode != "" {
			req.Mode = forceMode
		}
		if !authorizeUserOnlineDB(svcCtx, w, r, channelID, req.OnlineDBID, "用户自助 pull/bootstrap 须带 online_db_id，且须为本人 Binding") {
			return
		}
		if !authorizeUserSyncChannel(svcCtx, w, r, channelID) {
			return
		}
		res, err := dbsync.PullFromRemote(r.Context(), ch, svcCtx.DBSync.Store(), req)
		dur := time.Since(started)
		mode := req.Mode
		if mode == "" {
			mode = dbsync.PullModeBootstrap
		}
		if err != nil {
			logSyncReq(r, "pull/"+mode, channelID, req.Table, "", "err", err.Error(), dur, reqID)
			auditSync(svcCtx, r, "dbsync.pull.error", map[string]any{
				"channel_id": channelID, "mode": mode, "table": req.Table,
				"error": err.Error(), "ms": dur.Milliseconds(), "req_id": reqID,
			})
			if dbsync.IsRetryable(err) {
				authx.WriteRetryableError(w, http.StatusServiceUnavailable, err.Error())
				return
			}
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		n := 0
		if res != nil {
			n = len(res.Items) + len(res.PKs)
		}
		logSyncReq(r, "pull/"+mode, channelID, req.Table, "", "ok", "", dur, reqID)
		auditSync(svcCtx, r, "dbsync.pull", map[string]any{
			"channel_id": channelID, "mode": mode, "table": req.Table,
			"n": n, "ms": dur.Milliseconds(), "req_id": reqID,
		})
		httpx.OkJson(w, map[string]any{"success": true, "result": res})
	}
}

func agentSyncSchemaEnsureHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		started := time.Now()
		reqID := r.Header.Get("X-Request-Id")
		if !requireDBSync(svcCtx, w) {
			return
		}
		channelID := pathvar.Vars(r)["id"]
		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
		if err != nil {
			authx.WriteError(w, http.StatusNotFound, err.Error())
			return
		}
		var req dbsync.SchemaEnsureRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		online := strings.TrimSpace(req.OnlineDBID)
		if online == "" && len(req.Tables) > 0 {
			online = strings.TrimSpace(req.Tables[0].OnlineDBID)
			req.OnlineDBID = online
		}
		if !authorizeUserOnlineDB(svcCtx, w, r, channelID, online, "用户自助 schema/ensure 须带 online_db_id，且须为本人 Binding") {
			return
		}
		if !authorizeUserSyncChannel(svcCtx, w, r, channelID) {
			return
		}
		res, err := dbsync.EnsureSchemasOnRemote(r.Context(), ch, req)
		dur := time.Since(started)
		if err != nil {
			logSyncReq(r, "schema/ensure", channelID, "", "", "err", err.Error(), dur, reqID)
			auditSync(svcCtx, r, "dbsync.schema_ensure.error", map[string]any{
				"channel_id": channelID, "n": len(req.Tables), "error": err.Error(),
				"ms": dur.Milliseconds(), "req_id": reqID,
			})
			if dbsync.IsRetryable(err) {
				authx.WriteRetryableError(w, http.StatusServiceUnavailable, err.Error())
				return
			}
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		n := 0
		created := 0
		if res != nil {
			n = len(res.Results)
			for _, it := range res.Results {
				if it.Created {
					created++
				}
			}
		}
		logSyncReq(r, "schema/ensure", channelID, "", "", "ok", "", dur, reqID)
		auditSync(svcCtx, r, "dbsync.schema_ensure", map[string]any{
			"channel_id": channelID, "n": n, "created": created,
			"ms": dur.Milliseconds(), "req_id": reqID,
		})
		httpx.OkJson(w, map[string]any{"success": true, "result": res})
	}
}

func agentSyncSchemaDescribeHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		started := time.Now()
		reqID := r.Header.Get("X-Request-Id")
		if !requireDBSync(svcCtx, w) {
			return
		}
		channelID := pathvar.Vars(r)["id"]
		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
		if err != nil {
			authx.WriteError(w, http.StatusNotFound, err.Error())
			return
		}
		var req dbsync.SchemaDescribeRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		if !authorizeUserOnlineDB(svcCtx, w, r, channelID, req.OnlineDBID, "用户自助 schema 须带 online_db_id，且须为本人 Binding") {
			return
		}
		if !authorizeUserSyncChannel(svcCtx, w, r, channelID) {
			return
		}
		res, err := dbsync.DescribeSchemasFromRemote(r.Context(), ch, req)
		dur := time.Since(started)
		if err != nil {
			logSyncReq(r, "schema", channelID, "", "", "err", err.Error(), dur, reqID)
			auditSync(svcCtx, r, "dbsync.schema.error", map[string]any{
				"channel_id": channelID, "error": err.Error(),
				"ms": dur.Milliseconds(), "req_id": reqID,
			})
			if dbsync.IsRetryable(err) {
				authx.WriteRetryableError(w, http.StatusServiceUnavailable, err.Error())
				return
			}
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		n := 0
		if res != nil {
			n = len(res.Tables)
		}
		logSyncReq(r, "schema", channelID, "", "", "ok", "", dur, reqID)
		auditSync(svcCtx, r, "dbsync.schema", map[string]any{
			"channel_id": channelID, "n": n, "ms": dur.Milliseconds(), "req_id": reqID,
		})
		httpx.OkJson(w, map[string]any{"success": true, "result": res})
	}
}

func agentSyncSchemaFingerprintHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		started := time.Now()
		reqID := r.Header.Get("X-Request-Id")
		if !requireDBSync(svcCtx, w) {
			return
		}
		channelID := pathvar.Vars(r)["id"]
		ch, err := svcCtx.DBSync.Store().GetChannelForTenant(channelID, syncTenantID(r))
		if err != nil {
			authx.WriteError(w, http.StatusNotFound, err.Error())
			return
		}
		var req dbsync.FingerprintRequest
		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		if !authorizeUserOnlineDB(svcCtx, w, r, channelID, req.OnlineDBID, "用户自助 schema/fingerprint 须带 online_db_id，且须为本人 Binding") {
			return
		}
		if !authorizeUserSyncChannel(svcCtx, w, r, channelID) {
			return
		}
		res, err := dbsync.FingerprintRemoteTables(r.Context(), ch, req)
		dur := time.Since(started)
		if err != nil {
			logSyncReq(r, "schema/fingerprint", channelID, "", "", "err", err.Error(), dur, reqID)
			if dbsync.IsRetryable(err) {
				authx.WriteRetryableError(w, http.StatusServiceUnavailable, err.Error())
				return
			}
			authx.WriteError(w, http.StatusBadRequest, err.Error())
			return
		}
		n := 0
		if res != nil {
			n = len(res.Tables)
		}
		logSyncReq(r, "schema/fingerprint", channelID, "", "", "ok", "", dur, reqID)
		auditSync(svcCtx, r, "dbsync.schema_fingerprint", map[string]any{
			"channel_id": channelID, "n": n, "ms": dur.Milliseconds(), "req_id": reqID,
		})
		httpx.OkJson(w, map[string]any{"success": true, "result": res})
	}
}

func uniqueStringSlice(a, b []string) []string {
	seen := map[string]struct{}{}
	var out []string
	for _, xs := range [][]string{a, b} {
		for _, s := range xs {
			if s == "" {
				continue
			}
			if _, ok := seen[s]; ok {
				continue
			}
			seen[s] = struct{}{}
			out = append(out, s)
		}
	}
	return out
}