package firstrechargereward

import (
	"context"
	"errors"
	"net/http"
	"sort"
	"strings"
	"time"

	"chatapp3-golang/internal/model"
	"chatapp3-golang/internal/utils"

	"gorm.io/gorm"
)

func (s *Service) GetConfig(ctx context.Context, sysOrigin string) (*ConfigResponse, error) {
	sysOrigin = s.normalizeSysOrigin(sysOrigin)
	var configRow model.FirstRechargeRewardConfig
	err := s.db.WithContext(ctx).
		Where("sys_origin = ?", sysOrigin).
		First(&configRow).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return &ConfigResponse{
			Configured:   false,
			SysOrigin:    sysOrigin,
			Enabled:      false,
			LevelConfigs: []LevelPayload{},
		}, nil
	}
	if err != nil {
		return nil, err
	}
	levels, err := s.loadLevels(ctx, configRow.ID)
	if err != nil {
		return nil, err
	}
	rewardItems := s.loadRewardItemsMap(ctx, levels)
	return &ConfigResponse{
		Configured:   true,
		ID:           configRow.ID,
		SysOrigin:    configRow.SysOrigin,
		Enabled:      configRow.Enabled,
		UpdateTime:   formatDateTime(configRow.UpdateTime),
		LevelConfigs: buildLevelPayloads(levels, rewardItems, 0, 0, true),
	}, nil
}

func (s *Service) SaveConfig(ctx context.Context, req SaveConfigRequest) (*ConfigResponse, error) {
	requestID := req.ID.Int64()
	sysOrigin := s.normalizeSysOrigin(req.SysOrigin)
	levels, err := s.normalizeLevelInputs(req.LevelConfigs)
	if err != nil {
		return nil, err
	}
	if req.Enabled && !hasEnabledLevel(levels) {
		return nil, NewAppError(http.StatusBadRequest, "invalid_level_configs", "enabled config must contain at least one enabled level")
	}

	var savedConfigID int64
	if err := s.db.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		now := time.Now()
		var configRow model.FirstRechargeRewardConfig
		if requestID > 0 {
			err := tx.Where("id = ?", requestID).First(&configRow).Error
			if errors.Is(err, gorm.ErrRecordNotFound) {
				return NewAppError(http.StatusNotFound, "first_recharge_reward_config_not_found", "config not found")
			}
			if err != nil {
				return err
			}
			if strings.TrimSpace(req.SysOrigin) == "" {
				sysOrigin = configRow.SysOrigin
			}
		} else {
			err := tx.Where("sys_origin = ?", sysOrigin).First(&configRow).Error
			if errors.Is(err, gorm.ErrRecordNotFound) {
				configID, idErr := utils.NextID()
				if idErr != nil {
					return idErr
				}
				configRow = model.FirstRechargeRewardConfig{
					ID:         configID,
					SysOrigin:  sysOrigin,
					CreateTime: now,
				}
			} else if err != nil {
				return err
			}
		}

		configRow.SysOrigin = sysOrigin
		configRow.Enabled = req.Enabled
		configRow.UpdateTime = now
		if configRow.CreateTime.IsZero() {
			configRow.CreateTime = now
		}
		if err := tx.Save(&configRow).Error; err != nil {
			return err
		}
		if err := tx.Where("config_id = ?", configRow.ID).Delete(&model.FirstRechargeRewardLevel{}).Error; err != nil {
			return err
		}
		for index := range levels {
			levels[index].ConfigID = configRow.ID
			levels[index].CreateTime = now
			levels[index].UpdateTime = now
		}
		if len(levels) > 0 {
			if err := tx.Create(&levels).Error; err != nil {
				return err
			}
		}
		savedConfigID = configRow.ID
		return nil
	}); err != nil {
		return nil, err
	}

	return s.GetConfig(ctx, savedSysOrigin(ctx, s.db, savedConfigID, sysOrigin))
}

func (s *Service) normalizeLevelInputs(inputs []LevelInput) ([]model.FirstRechargeRewardLevel, error) {
	if len(inputs) == 0 {
		return nil, NewAppError(http.StatusBadRequest, "invalid_level_configs", "levelConfigs is required")
	}
	seenLevels := make(map[int]struct{}, len(inputs))
	seenAmounts := make(map[int64]struct{}, len(inputs))
	rows := make([]model.FirstRechargeRewardLevel, 0, len(inputs))
	for _, item := range inputs {
		if item.Level <= 0 {
			return nil, NewAppError(http.StatusBadRequest, "invalid_level", "level must be greater than 0")
		}
		amountCents := item.RechargeAmount.Cents()
		if amountCents == 0 && item.RechargeAmountCents > 0 {
			amountCents = item.RechargeAmountCents
		}
		if amountCents <= 0 {
			return nil, NewAppError(http.StatusBadRequest, "invalid_recharge_amount", "rechargeAmount must be greater than 0")
		}
		rewardGroupID := item.RewardGroupID.Int64()
		if rewardGroupID <= 0 {
			return nil, NewAppError(http.StatusBadRequest, "invalid_reward_group", "rewardGroupId is required")
		}
		if _, exists := seenLevels[item.Level]; exists {
			return nil, NewAppError(http.StatusBadRequest, "duplicate_level", "levelConfigs must not contain duplicate levels")
		}
		if _, exists := seenAmounts[amountCents]; exists {
			return nil, NewAppError(http.StatusBadRequest, "duplicate_recharge_amount", "levelConfigs must not contain duplicate rechargeAmount")
		}
		seenLevels[item.Level] = struct{}{}
		seenAmounts[amountCents] = struct{}{}
		id, err := utils.NextID()
		if err != nil {
			return nil, err
		}
		rows = append(rows, model.FirstRechargeRewardLevel{
			ID:                  id,
			Level:               item.Level,
			RechargeAmountCents: amountCents,
			RewardGroupID:       rewardGroupID,
			RewardGroupName:     strings.TrimSpace(item.RewardGroupName),
			Enabled:             item.Enabled,
		})
	}
	sort.Slice(rows, func(i, j int) bool {
		if rows[i].RechargeAmountCents == rows[j].RechargeAmountCents {
			return rows[i].Level < rows[j].Level
		}
		return rows[i].RechargeAmountCents < rows[j].RechargeAmountCents
	})
	return rows, nil
}

func (s *Service) loadConfigBundle(ctx context.Context, sysOrigin string) (*configBundle, error) {
	sysOrigin = s.normalizeSysOrigin(sysOrigin)
	var configRow model.FirstRechargeRewardConfig
	err := s.db.WithContext(ctx).
		Where("sys_origin = ?", sysOrigin).
		First(&configRow).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return &configBundle{}, nil
	}
	if err != nil {
		return nil, err
	}
	levels, err := s.loadLevels(ctx, configRow.ID)
	if err != nil {
		return nil, err
	}
	return &configBundle{
		Config: refConfigSnapshot(configSnapshotFromModel(configRow)),
		Levels: levels,
	}, nil
}

func (s *Service) loadLevels(ctx context.Context, configID int64) ([]levelSnapshot, error) {
	if configID <= 0 {
		return []levelSnapshot{}, nil
	}
	var rows []model.FirstRechargeRewardLevel
	if err := s.db.WithContext(ctx).
		Where("config_id = ?", configID).
		Order("recharge_amount_cents asc").
		Order("level asc").
		Find(&rows).Error; err != nil {
		return nil, err
	}
	levels := make([]levelSnapshot, 0, len(rows))
	for _, row := range rows {
		levels = append(levels, levelSnapshotFromModel(row))
	}
	sortLevels(levels)
	return levels, nil
}

func hasEnabledLevel(levels []model.FirstRechargeRewardLevel) bool {
	for _, level := range levels {
		if level.Enabled {
			return true
		}
	}
	return false
}

func savedSysOrigin(ctx context.Context, db dbHandle, id int64, fallback string) string {
	var row model.FirstRechargeRewardConfig
	if id > 0 && db != nil {
		if err := db.WithContext(ctx).Where("id = ?", id).First(&row).Error; err == nil {
			return row.SysOrigin
		}
	}
	return fallback
}