package binlog

import (
	"fmt"

	"b612.me/mysql/gtid"
	"github.com/starainrt/go-mysql/mysql"
	"github.com/starainrt/go-mysql/replication"
)

func ParseBinlogEvent(ev *replication.BinlogEvent) []BinlogEvent {
	var buf [1]BinlogEvent
	sig := &buf[0]

	switch ev.Header.EventType {
	case replication.ANONYMOUS_GTID_EVENT:
		sig.Data = "anonymous-gtid-event:1"
		sig.Type = "gtid"

	case replication.WRITE_ROWS_EVENTv1, replication.WRITE_ROWS_EVENTv2:
		wrEvent, ok := ev.Event.(*replication.RowsEvent)
		if !ok {
			return nil
		}
		sig.DB = string(wrEvent.Table.Schema)
		sig.TB = string(wrEvent.Table.Table)
		sig.Type = "insert"
		sig.RowCnt = uint32(len(wrEvent.Rows))
		sig.Rows = normalizeRowsByUnsigned(wrEvent)
		sig.ColumnTypes = cloneColumnTypes(wrEvent.Table)
		sig.ColumnCollationIDs = buildColumnCollationIDs(wrEvent.Table)

	case replication.UPDATE_ROWS_EVENTv1, replication.UPDATE_ROWS_EVENTv2:
		wrEvent, ok := ev.Event.(*replication.RowsEvent)
		if !ok {
			return nil
		}
		sig.DB = string(wrEvent.Table.Schema)
		sig.TB = string(wrEvent.Table.Table)
		sig.Type = "update"
		sig.RowCnt = uint32(len(wrEvent.Rows)) / 2
		sig.Rows = normalizeRowsByUnsigned(wrEvent)
		sig.ColumnTypes = cloneColumnTypes(wrEvent.Table)
		sig.ColumnCollationIDs = buildColumnCollationIDs(wrEvent.Table)

	case replication.DELETE_ROWS_EVENTv1, replication.DELETE_ROWS_EVENTv2:
		wrEvent, ok := ev.Event.(*replication.RowsEvent)
		if !ok {
			return nil
		}
		sig.DB = string(wrEvent.Table.Schema)
		sig.TB = string(wrEvent.Table.Table)
		sig.Type = "delete"
		sig.RowCnt = uint32(len(wrEvent.Rows))
		sig.Rows = normalizeRowsByUnsigned(wrEvent)
		sig.ColumnTypes = cloneColumnTypes(wrEvent.Table)
		sig.ColumnCollationIDs = buildColumnCollationIDs(wrEvent.Table)

	case replication.TABLE_MAP_EVENT:
		tableEvent, ok := ev.Event.(*replication.TableMapEvent)
		if !ok {
			return nil
		}
		sig.DB = string(tableEvent.Schema)
		sig.TB = string(tableEvent.Table)
		sig.Type = "tablemap"

	case replication.ROWS_QUERY_EVENT:
		queryEvent, ok := ev.Event.(*replication.RowsQueryEvent)
		if !ok {
			return nil
		}
		sig.Data = string(queryEvent.Query)
		sig.Type = "rowsquery"

	case replication.QUERY_EVENT:
		queryEvent, ok := ev.Event.(*replication.QueryEvent)
		if !ok {
			return nil
		}
		sig.DB = string(queryEvent.Schema)
		sig.Data = string(queryEvent.Query)
		sig.Type = "query"

	case replication.MARIADB_GTID_EVENT:
		sig.Data = "begin"
		sig.Type = "query"

	case replication.XID_EVENT:
		sig.Data = "commit"
		sig.Type = "query"

	case replication.GTID_EVENT:
		ge, ok := ev.Event.(*replication.GTIDEvent)
		if !ok {
			return nil
		}
		gid, err := gtid.Parse(fmt.Sprintf("%s:%d", bytesToUuid(ge.SID), ge.GNO))
		if err != nil {
			sig.Data = fmt.Sprintf("invalid-gtid:%s:%d", bytesToUuid(ge.SID), ge.GNO)
		} else {
			sig.Data = gid.String()
		}
		sig.Type = "gtid"

	case replication.TRANSACTION_PAYLOAD_EVENT:
		ge, ok := ev.Event.(*replication.TransactionPayloadEvent)
		if !ok {
			return nil
		}
		res := make([]BinlogEvent, 0, len(ge.Events))
		for _, val := range ge.Events {
			res = append(res, ParseBinlogEvent(val)...)
		}
		compressionType := getCompressionTypeName(ge.CompressionType)
		for idx := range res {
			res[idx].CompressionType = compressionType
		}
		return res
	}

	// 返回栈上数组的切片。调用方在当前迭代内立即消费，不持有跨迭代引用，安全。
	return buf[:]
}

func normalizeRowsByUnsigned(wrEvent *replication.RowsEvent) [][]interface{} {
	if wrEvent == nil || wrEvent.Table == nil || len(wrEvent.Rows) == 0 {
		if wrEvent == nil {
			return nil
		}
		return wrEvent.Rows
	}

	unsignedMap := wrEvent.Table.UnsignedMap()
	if len(unsignedMap) == 0 {
		return wrEvent.Rows
	}

	columnTypes := wrEvent.Table.ColumnType
	if len(columnTypes) == 0 {
		return wrEvent.Rows
	}

	for rowIdx := range wrEvent.Rows {
		row := wrEvent.Rows[rowIdx]
		for colIdx := range row {
			if !unsignedMap[colIdx] {
				continue
			}
			if colIdx >= len(columnTypes) {
				continue
			}
			row[colIdx] = normalizeUnsignedValue(row[colIdx], columnTypes[colIdx])
		}
	}
	return wrEvent.Rows
}

func cloneColumnTypes(table *replication.TableMapEvent) []int {
	if table == nil || len(table.ColumnType) == 0 {
		return nil
	}
	ret := make([]int, len(table.ColumnType))
	for i, t := range table.ColumnType {
		ret[i] = int(t)
	}
	return ret
}

func buildColumnCollationIDs(table *replication.TableMapEvent) []uint64 {
	if table == nil {
		return nil
	}

	columnCount := len(table.ColumnType)
	if columnCount == 0 && table.ColumnCount > 0 {
		columnCount = int(table.ColumnCount)
	}
	if columnCount == 0 {
		return nil
	}

	ret := make([]uint64, columnCount)
	hasValue := false

	for idx, collationID := range table.CollationMap() {
		if idx < 0 || idx >= columnCount {
			continue
		}
		ret[idx] = collationID
		hasValue = hasValue || collationID != 0
	}
	for idx, collationID := range table.EnumSetCollationMap() {
		if idx < 0 || idx >= columnCount {
			continue
		}
		if ret[idx] == 0 {
			ret[idx] = collationID
		}
		hasValue = hasValue || collationID != 0
	}

	if !hasValue {
		return nil
	}
	return ret
}

func normalizeUnsignedValue(v interface{}, colType byte) interface{} {
	signed, ok := signedToInt64(v)
	if !ok {
		return v
	}

	switch colType {
	case mysql.MYSQL_TYPE_TINY:
		return uint8(signed)
	case mysql.MYSQL_TYPE_SHORT:
		return uint16(signed)
	case mysql.MYSQL_TYPE_INT24:
		return uint32(uint32(int32(signed)) & 0x00FFFFFF)
	case mysql.MYSQL_TYPE_LONG:
		return uint32(signed)
	case mysql.MYSQL_TYPE_LONGLONG:
		return uint64(signed)
	default:
		return v
	}
}

func signedToInt64(v interface{}) (int64, bool) {
	switch x := v.(type) {
	case int8:
		return int64(x), true
	case int16:
		return int64(x), true
	case int32:
		return int64(x), true
	case int64:
		return x, true
	case int:
		return int64(x), true
	default:
		return 0, false
	}
}

func getCompressionTypeName(code uint64) string {
	switch code {
	case CompressionZSTD:
		return "ZSTD"
	case CompressionNone:
		return ""
	default:
		return fmt.Sprintf("UNKNOWN(%d)", code)
	}
}