package business

import (
	"fmt"
	"gorm.io/gorm"
	"kra/pkg/database/migration"
	"strings"
)

func migrateAlertV2(db *gorm.DB) error {
	if err := migration.CreateMissingTables(db, &alertGapPO{}, &alertExemptionPO{}, &alertChannelLockPO{}, &alertRulePO{}, &alertRecordPO{}); err != nil {
		return err
	}
	for _, item := range []struct {
		model  any
		fields []string
	}{
		{&alertRulePO{}, []string{"ConditionMode", "AmountDirection", "AmountThreshold"}},
		{&alertRecordPO{}, []string{"TotalPlayers", "TotalPay", "WarningColor", "IndependentRule"}},
	} {
		if db.Dialector.Name() == "mysql" {
			statement := &gorm.Statement{DB: db}
			if err := statement.Parse(item.model); err != nil {
				return err
			}
			columns := []string{}
			args := []any{}
			for _, name := range item.fields {
				if !db.Migrator().HasColumn(item.model, name) {
					field := statement.Schema.LookUpField(name)
					definition := db.Migrator().FullDataTypeOf(field)
					columns = append(columns, "ADD COLUMN `"+field.DBName+"` "+definition.SQL)
					args = append(args, definition.Vars...)
				}
			}
			// MySQL 5.7 添加普通列会重建表；合并执行，避免每个字段重建一次。
			if len(columns) > 0 {
				if err := db.Exec("ALTER TABLE `"+statement.Schema.Table+"` "+strings.Join(columns, ", ")+", ALGORITHM=INPLACE, LOCK=NONE", args...).Error; err != nil {
					return err
				}
			}
			continue
		}
		for _, field := range item.fields {
			if !db.Migrator().HasColumn(item.model, field) {
				if err := db.Migrator().AddColumn(item.model, field); err != nil {
					return err
				}
			}
		}
	}
	if err := migrateRegistrationIndex(db); err != nil {
		return err
	}
	if err := migrateAlertV2UniqueKey(db); err != nil {
		return err
	}
	return migrateQueryIndexes(db, alertV2QueryIndexes)
}

func migrateAlertV2UniqueKey(db *gorm.DB) error {
	if db.Dialector.Name() != "mysql" {
		return nil
	}
	// 旧唯一键将已忽略视为未闭环，也无法容纳同类的两条绝对值规则。
	// 保留旧生成列，原子替换唯一键；不改写、合并或删除历史记录。
	clauses := []string{}
	if !db.Migrator().HasColumn("sys_alert_record", "v2_open_key") {
		// MySQL 5.7 的在线虚拟列变更不能与索引变更放在同一 ALTER 中。
		if err := db.Exec("ALTER TABLE sys_alert_record ADD COLUMN v2_open_key BIGINT UNSIGNED GENERATED ALWAYS AS (CASE WHEN status IN (1,2,3,4) THEN CASE WHEN independent_rule=1 THEN rule_id ELSE 0 END ELSE NULL END) VIRTUAL, ALGORITHM=INPLACE, LOCK=NONE").Error; err != nil {
			return err
		}
	} else {
		var column struct {
			GenerationExpression string
			Extra                string
		}
		if err := db.Raw("SELECT generation_expression,extra FROM information_schema.columns WHERE table_schema=DATABASE() AND table_name='sys_alert_record' AND column_name='v2_open_key'").Scan(&column).Error; err != nil {
			return err
		}
		normalize := strings.NewReplacer("`", "", " ", "", "\n", "", "\t", "", "(", "", ")", "")
		if normalize.Replace(strings.ToLower(column.GenerationExpression)) != "casewhenstatusin1,2,3,4thencasewhenindependent_rule=1thenrule_idelse0endelsenullend" || !strings.Contains(strings.ToUpper(column.Extra), "VIRTUAL GENERATED") {
			return fmt.Errorf("sys_alert_record.v2_open_key 的现有定义不符，未修改原唯一索引")
		}
	}
	var existing []struct {
		ColumnName string
		NonUnique  int
		SubPart    *int
	}
	if err := db.Raw("SELECT column_name,non_unique,sub_part FROM information_schema.statistics WHERE table_schema=DATABASE() AND table_name='sys_alert_record' AND index_name='uk_alert_record_v2_open' ORDER BY seq_in_index").Scan(&existing).Error; err != nil {
		return err
	}
	replaceV2 := false
	if len(existing) > 0 {
		columns := []string{}
		for _, column := range existing {
			if column.NonUnique != 0 || column.SubPart != nil {
				return fmt.Errorf("sys_alert_record.uk_alert_record_v2_open 必须是完整字段的唯一索引")
			}
			columns = append(columns, column.ColumnName)
		}
		layout := strings.Join(columns, ",")
		replaceV2 = layout == "platform_code,target_promote_id,rule_type,v2_open_key"
		if layout != "business_id,platform_code,target_promote_id,rule_type,v2_open_key" && !replaceV2 {
			return fmt.Errorf("sys_alert_record.uk_alert_record_v2_open 的现有索引列不符，未修改原唯一索引")
		}
	}
	for _, name := range []string{"uk_alert_record_unclosed", "uk_alert_record_daily"} {
		if db.Migrator().HasIndex("sys_alert_record", name) {
			clauses = append(clauses, "DROP INDEX `"+name+"`")
		}
	}
	if replaceV2 {
		clauses = append(clauses, "DROP INDEX uk_alert_record_v2_open")
	}
	if len(existing) == 0 || replaceV2 {
		clauses = append(clauses, "ADD UNIQUE INDEX uk_alert_record_v2_open(business_id,platform_code,target_promote_id,rule_type,v2_open_key)")
	}
	if len(clauses) == 0 {
		return nil
	}
	return db.Exec("ALTER TABLE sys_alert_record " + strings.Join(clauses, ", ") + ", ALGORITHM=INPLACE, LOCK=NONE").Error
}

var alertV2QueryIndexes = []businessQueryIndex{
	{"sys_alert_record", "idx_alert_owner_status_time", []string{"business_id", "status", "created_at", "id"}},
	{"sys_alert_record", "idx_alert_channel_type_time", []string{"platform_code", "target_promote_id", "rule_type", "created_at", "id"}},
	{"sys_alert_record", "idx_alert_owner_time", []string{"business_id", "created_at", "id"}},
	{"sys_alert_record", "idx_alert_created", []string{"created_at", "id"}},
	{"sys_alert_operation_log", "idx_alert_log_time", []string{"alert_id", "created_at", "id"}},
	{"tab_spend", "idx_alert_spend_window", []string{"source_db", "promote_id", "pay_status", "pay_time", "pay_amount"}},
	{"tab_user", "idx_alert_user_window", []string{"source_db", "promote_id", "sw_register_time_unix", "puid"}},
	{"tab_promote", "idx_alert_promote_tree", []string{"source_db", "top_promote_id", "id"}},
}