// Package handler provides HTTP handlers for various endpoints.
package handler

import (
	"context"
	"fmt"
	"maps"
	"slices"
	"strings"

	"github.com/gofrs/uuid"

	"modelRT/common/errcode"
	"modelRT/constants"
	"modelRT/database"
	"modelRT/diagram"
	"modelRT/logger"
	"modelRT/orm"

	"github.com/gin-gonic/gin"
)

// ComponentAttributeQueryHandler define circuit diagram component attribute value query process API
func ComponentAttributeQueryHandler(c *gin.Context) {
	pgClient := database.GetPostgresDBClient()

	tokens := c.Param("tokens")
	if tokens == "" {
		err := fmt.Errorf("tokens is missing from the path")
		logger.Error(c, "query tokens from path failed", "error", err, "url", c.Request.RequestURI)
		renderFailure(c, constants.RespCodeInvalidParams, err.Error(), nil)
		return
	}

	tokenSlice := strings.Split(tokens, ",")
	queryResults := make(map[string]queryResult)
	cacheQueryMap := make(map[string][]cacheQueryItem)

	for _, token := range tokenSlice {
		slices := strings.Split(token, ".")
		if len(slices) < 7 {
			queryResults[token] = queryResult{err: errcode.ErrInvalidToken}
			continue
		}
		hSetKey := fmt.Sprintf("%s_%s", slices[4], slices[5])
		cacheQueryMap[hSetKey] = append(cacheQueryMap[hSetKey], cacheQueryItem{
			token:               token,
			attributeCompTag:    slices[4],
			attributeExtendType: slices[5],
			attributeName:       slices[6],
		})
	}

	dbQueryMap := make(map[string][]cacheQueryItem)
	var secondaryQueryCount int
	for hSetKey, items := range cacheQueryMap {
		hset := diagram.NewRedisHash(c, hSetKey, 5000, false)
		cacheData, err := hset.HGetAll()
		if err != nil {
			logger.Warn(c, "redis hgetall failed", "key", hSetKey, "err", err)
		}
		for _, item := range items {
			if val, ok := cacheData[item.attributeName]; ok {
				queryResults[item.token] = queryResult{value: val}
			} else {
				dbQueryMap[item.attributeCompTag] = append(dbQueryMap[item.attributeCompTag], item)
				secondaryQueryCount++
			}
		}
	}

	if secondaryQueryCount == 0 {
		renderQuerySuccess(c, queryResults, tokenSlice)
		return
	}

	// enable transaction processing for secondary database queries
	tx := pgClient.WithContext(c).Begin()
	if tx.Error != nil {
		logger.Error(c, "begin postgres transaction failed", "error", tx.Error)
		renderFailure(c, constants.RespCodeServerError, "begin postgres database transaction failed", nil)
		return
	}
	defer tx.Rollback()

	allCompTags := slices.Collect(maps.Keys(dbQueryMap))
	compModelMap, err := database.QueryComponentByCompTags(c, tx, allCompTags)
	if err != nil {
		logger.Error(c, "query component info from postgres database failed", "error", err)
		renderFailure(c, constants.RespCodeServerError, "query component meta failed", nil)
		return
	}

	// batch retrieve component metadata
	identifiers := make([]orm.ProjectIdentifier, 0, secondaryQueryCount)
	for tag, items := range dbQueryMap {
		comp, ok := compModelMap[tag]
		if !ok {
			for _, it := range items {
				queryResults[it.token] = queryResult{err: errcode.ErrFoundTargetFailed}
			}
			continue
		}
		for i := range items {
			items[i].attributeModelName = comp.ModelName
			items[i].globalUUID = comp.GlobalUUID
			identifiers = append(identifiers, orm.ProjectIdentifier{
				Token: items[i].token, Tag: comp.ModelName, MetaModel: items[i].attributeExtendType,
			})
		}
	}

	tableNameMap, err := database.BatchGetProjectNames(tx, identifiers)
	if err != nil {
		logger.Error(c, "batch get table names from postgres database failed", "error", err)
		renderFailure(c, constants.RespCodeServerError, "batch get table names from postgres database failed", nil)
		return
	}

	redisSyncMap := make(map[string][]cacheQueryItem)
	for _, items := range dbQueryMap {
		for _, item := range items {
			if _, exists := queryResults[item.token]; exists {
				continue
			}

			tbl, ok := tableNameMap[orm.ProjectIdentifier{Tag: item.attributeModelName, MetaModel: item.attributeExtendType}]
			if !ok {
				queryResults[item.token] = queryResult{err: errcode.ErrFoundTargetFailed}
				continue
			}

			var dbVal string
			res := tx.Table(tbl).Select(item.attributeName).Where("global_uuid = ?", item.globalUUID).Scan(&dbVal)
			if res.Error != nil || res.RowsAffected == 0 {
				queryResults[item.token] = queryResult{err: errcode.ErrDBQueryFailed}
				continue
			}

			queryResults[item.token] = queryResult{value: dbVal}
			item.attributeVal = dbVal
			hKey := fmt.Sprintf("%s_%s", item.attributeCompTag, item.attributeExtendType)
			redisSyncMap[hKey] = append(redisSyncMap[hKey], item)
		}
	}

	if err := tx.Commit().Error; err != nil {
		logger.Error(c, "postgres database transaction commit failed", "error", err)
		renderFailure(c, constants.RespCodeServerError, "postgres database transaction commit failed", nil)
		return
	}

	for hKey, items := range redisSyncMap {
		go backfillRedis(c.Copy(), hKey, items)
	}

	renderQuerySuccess(c, queryResults, tokenSlice)
}

func backfillRedis(ctx context.Context, hSetKey string, items []cacheQueryItem) {
	hset := diagram.NewRedisHash(ctx, hSetKey, 5000, false)
	fields := make(map[string]any, len(items))
	for _, item := range items {
		// 只回填有值的项
		if item.attributeVal != "" {
			fields[item.attributeName] = item.attributeVal
		}
	}

	if len(fields) > 0 {
		if err := hset.SetRedisHashByMap(fields); err != nil {
			logger.Error(ctx, "async backfill redis failed", "hash_key", hSetKey, "error", err)
		} else {
			logger.Info(ctx, "async backfill redis success", "hash_key", hSetKey, "count", len(fields))
		}
	}
}

type cacheQueryItem struct {
	globalUUID          uuid.UUID
	token               string
	attributeCompTag    string
	attributeModelName  string
	attributeExtendType string
	attributeName       string
	attributeVal        string
}

type queryResult struct {
	err   *errcode.AppError
	value string
}