package signinreward

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

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

	"gorm.io/gorm"
)

// GetConfig 返回后台配置页使用的签到奖励配置。
func (s *SignInRewardService) GetConfig(ctx context.Context, sysOrigin string) (*SignInRewardConfigResponse, error) {
	bundle, err := s.loadConfigBundle(ctx, sysOrigin)
	if err != nil {
		return nil, err
	}
	if bundle.Config == nil {
		return &SignInRewardConfigResponse{
			Configured: false,
			SysOrigin:  normalizeSignInRewardSysOrigin(sysOrigin),
			Timezone:   signInRewardDefaultTimezone,
			CycleDays:  signInRewardCycleLength,
			Days:       buildDefaultSignInRewardDays(),
		}, nil
	}
	return &SignInRewardConfigResponse{
		Configured: true,
		ID:         bundle.Config.ID,
		SysOrigin:  bundle.Config.SysOrigin,
		Enabled:    bundle.Config.Enabled,
		Timezone:   bundle.Config.Timezone,
		CycleDays:  signInRewardCycleLength,
		Days:       buildAdminDayPayloads(bundle.Days),
		UpdateTime: formatSignInRewardDateTime(bundle.Config.UpdateTime),
	}, nil
}

// SaveConfig 保存签到奖励后台配置。
func (s *SignInRewardService) SaveConfig(ctx context.Context, req SaveSignInRewardConfigRequest) (*SignInRewardConfigResponse, error) {
	sysOrigin := normalizeSignInRewardSysOrigin(req.SysOrigin)
	if sysOrigin == "" {
		return nil, NewAppError(http.StatusBadRequest, "bad_request", "sysOrigin is required")
	}

	timezone := normalizeSignInRewardTimezone(req.Timezone)
	if _, err := time.LoadLocation(timezone); err != nil {
		return nil, NewAppError(http.StatusBadRequest, "invalid_timezone", err.Error())
	}

	normalizedDays, err := normalizeSaveDays(req.Days, req.Enabled)
	if err != nil {
		return nil, err
	}

	now := time.Now()
	var configID int64
	if err := s.repo.DB.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
		var configRow model.SignInRewardConfig
		if err := tx.Where("sys_origin = ?", sysOrigin).First(&configRow).Error; errors.Is(err, gorm.ErrRecordNotFound) {
			nextID, idErr := utils.NextID()
			if idErr != nil {
				return idErr
			}
			configRow = model.SignInRewardConfig{
				ID:         nextID,
				SysOrigin:  sysOrigin,
				CreateTime: now,
			}
		} else if err != nil {
			return err
		}

		configRow.Enabled = req.Enabled
		configRow.Timezone = timezone
		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.SignInRewardDayConfig{}).Error; err != nil {
			return err
		}

		rows := make([]model.SignInRewardDayConfig, 0, len(normalizedDays))
		for _, item := range normalizedDays {
			dayID, idErr := utils.NextID()
			if idErr != nil {
				return idErr
			}
			rows = append(rows, model.SignInRewardDayConfig{
				ID:              dayID,
				ConfigID:        configRow.ID,
				DayIndex:        item.DayIndex,
				GoldAmount:      0,
				RewardGroupID:   item.RewardGroupID.Int64Ptr(),
				RewardGroupName: strings.TrimSpace(item.RewardGroupName),
				CreateTime:      now,
				UpdateTime:      now,
			})
		}
		if len(rows) > 0 {
			if err := tx.Create(&rows).Error; err != nil {
				return err
			}
		}
		configID = configRow.ID
		return nil
	}); err != nil {
		return nil, err
	}

	_ = configID
	return s.GetConfig(ctx, sysOrigin)
}

func normalizeSaveDays(days []SignInRewardDayConfigInput, enabled bool) ([]SignInRewardDayConfigInput, error) {
	if len(days) != signInRewardCycleLength {
		return nil, NewAppError(http.StatusBadRequest, "invalid_days", "days must contain exactly 7 items")
	}

	seen := make(map[int]struct{}, len(days))
	normalized := make([]SignInRewardDayConfigInput, 0, len(days))
	for _, item := range days {
		if item.DayIndex < 1 || item.DayIndex > signInRewardCycleLength {
			return nil, NewAppError(http.StatusBadRequest, "invalid_day_index", "dayIndex must be between 1 and 7")
		}
		if _, exists := seen[item.DayIndex]; exists {
			return nil, NewAppError(http.StatusBadRequest, "duplicate_day_index", "dayIndex must be unique")
		}
		seen[item.DayIndex] = struct{}{}
		if enabled && item.RewardGroupID.Int64Ptr() == nil {
			return nil, NewAppError(http.StatusBadRequest, "empty_day_reward", "each enabled day must configure rewardGroupId")
		}
		normalized = append(normalized, SignInRewardDayConfigInput{
			DayIndex:        item.DayIndex,
			RewardGroupID:   item.RewardGroupID,
			RewardGroupName: strings.TrimSpace(item.RewardGroupName),
		})
	}
	sort.Slice(normalized, func(i, j int) bool {
		return normalized[i].DayIndex < normalized[j].DayIndex
	})
	return normalized, nil
}

func (s *SignInRewardService) loadConfigBundle(ctx context.Context, sysOrigin string) (*signInRewardConfigBundle, error) {
	sysOrigin = normalizeSignInRewardSysOrigin(sysOrigin)
	if sysOrigin == "" {
		return nil, NewAppError(http.StatusBadRequest, "bad_request", "sysOrigin is required")
	}

	var configRow model.SignInRewardConfig
	err := s.repo.DB.WithContext(ctx).Where("sys_origin = ?", sysOrigin).First(&configRow).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return &signInRewardConfigBundle{}, nil
	}
	if err != nil {
		return nil, err
	}

	var dayRows []model.SignInRewardDayConfig
	if err := s.repo.DB.WithContext(ctx).
		Where("config_id = ?", configRow.ID).
		Order("day_index asc").
		Find(&dayRows).Error; err != nil {
		return nil, err
	}

	result := &signInRewardConfigBundle{
		Config: &signInRewardConfigSnapshot{
			ID:         configRow.ID,
			SysOrigin:  configRow.SysOrigin,
			Enabled:    configRow.Enabled,
			Timezone:   normalizeSignInRewardTimezone(configRow.Timezone),
			UpdateTime: configRow.UpdateTime,
		},
		Days: make([]signInRewardDaySnapshot, 0, len(dayRows)),
	}
	for _, row := range dayRows {
		result.Days = append(result.Days, signInRewardDaySnapshot{
			ID:              row.ID,
			DayIndex:        row.DayIndex,
			RewardGroupID:   row.RewardGroupID,
			RewardGroupName: strings.TrimSpace(row.RewardGroupName),
		})
	}
	fillMissingSignInRewardDays(&result.Days)
	return result, nil
}

func buildDefaultSignInRewardDays() []SignInRewardDayPayload {
	days := make([]SignInRewardDayPayload, 0, signInRewardCycleLength)
	for dayIndex := 1; dayIndex <= signInRewardCycleLength; dayIndex++ {
		days = append(days, SignInRewardDayPayload{
			DayIndex:    dayIndex,
			RewardItems: []SignInRewardRewardItem{},
		})
	}
	return days
}

func buildAdminDayPayloads(days []signInRewardDaySnapshot) []SignInRewardDayPayload {
	payloads := make([]SignInRewardDayPayload, 0, len(days))
	for _, item := range days {
		payloads = append(payloads, SignInRewardDayPayload{
			DayIndex:        item.DayIndex,
			RewardGroupID:   item.RewardGroupID,
			RewardGroupName: item.RewardGroupName,
			RewardItems:     []SignInRewardRewardItem{},
		})
	}
	return payloads
}

func fillMissingSignInRewardDays(days *[]signInRewardDaySnapshot) {
	dayMap := make(map[int]signInRewardDaySnapshot, len(*days))
	for _, item := range *days {
		dayMap[item.DayIndex] = item
	}
	filled := make([]signInRewardDaySnapshot, 0, signInRewardCycleLength)
	for dayIndex := 1; dayIndex <= signInRewardCycleLength; dayIndex++ {
		if item, ok := dayMap[dayIndex]; ok {
			filled = append(filled, item)
			continue
		}
		filled = append(filled, signInRewardDaySnapshot{DayIndex: dayIndex})
	}
	*days = filled
}

func formatSignInRewardDateTime(t time.Time) string {
	if t.IsZero() {
		return ""
	}
	return t.Format("2006-01-02 15:04:05")
}