package binlog

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strings"

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

func ParseBinlogWithFilter(path string, pos int64, filter BinlogFilter, fx func(Transaction) bool) error {
	if hasConfiguredTablePatterns(filter.IncludeTables) && hasConfiguredTablePatterns(filter.ExcludeTables) {
		return fmt.Errorf("invalid filter: include-tables and exclude-tables cannot be set at the same time")
	}

	if !staros.Exists(path) {
		return os.ErrNotExist
	}

	f, err := os.Open(path)
	if err != nil {
		return err
	}
	defer f.Close()

	parser := replication.NewBinlogParser()
	parser.SetParseTime(false)
	parser.SetUseDecimal(false)

	if pos != 0 {
		if err := seekToPosition(f, parser, pos); err != nil {
			return err
		}
	} else {
		if err := validateBinlogHeader(f); err != nil {
			return err
		}
	}

	br := bufio.NewReaderSize(f, defaultReadBufSize)
	return parseBinlogWithFilter(br, parser, filter, fx)
}

func parseBinlogWithFilter(r io.Reader, parser *replication.BinlogParser, filter BinlogFilter, fn func(Transaction) bool) error {
	if hasConfiguredTablePatterns(filter.IncludeTables) && hasConfiguredTablePatterns(filter.ExcludeTables) {
		return fmt.Errorf("invalid filter: include-tables and exclude-tables cannot be set at the same time")
	}

	var subGtid, inGtid, exGtid *gtid.Gtid
	var err error

	includeMatcher, excludeMatcher, err := prepareTableMatchers(filter)
	if err != nil {
		return err
	}

	if filter.IncludeGtid != "" {
		inGtid, err = gtid.Parse(filter.IncludeGtid)
		if err != nil {
			return fmt.Errorf("parse include gtid failed: %w", err)
		}
		subGtid = inGtid.Clone()
	}
	if filter.ExcludeGtid != "" {
		exGtid, err = gtid.Parse(filter.ExcludeGtid)
		if err != nil {
			return fmt.Errorf("parse exclude gtid failed: %w", err)
		}
	}

	var (
		tbMapPos       uint32
		skipCurrentTxn bool
		tx             Transaction
		headBuf        = make([]byte, replication.EventHeaderSize)
	)
	currentGtid := ""

	callFn := func(tx Transaction) bool {
		if fn == nil {
			return true
		}

		fillTimeLazy(&tx)

		if !filter.StartDate.IsZero() && filter.StartDate.After(tx.Time) {
			return true
		}
		if !filter.EndDate.IsZero() && filter.EndDate.Before(tx.Time) {
			return true
		}
		if filter.StartPos != 0 && filter.StartPos > tx.StartPos {
			return true
		}
		if filter.EndPos != 0 && filter.EndPos < tx.EndPos {
			return true
		}
		if filter.BigThan != 0 && filter.BigThan > tx.Size {
			return true
		}
		if filter.SmallThan != 0 && filter.SmallThan < tx.Size {
			return true
		}
		if !filter.OnlyShowGtid && filter.OnlyShowDML && tx.dmlEventCount == 0 {
			return true
		}

		txs, matched, pickAll, skipAll := selectVisibleTxDetails(tx, includeMatcher, excludeMatcher, filter)
		if pickAll {
			return fn(tx)
		}
		if skipAll {
			return true
		}

		if matched {
			tx.Txs = txs
			recomputeTxStatsFromVisibleDetails(&tx)
		}
		if !matched && includeMatcher != nil {
			return true
		}
		if len(tx.Txs) == 0 && matched {
			return true
		}
		return fn(tx)
	}

	for {
		h, err := readEventHeader(r, parser, headBuf)
		if err == io.EOF {
			if currentGtid != "" {
				finalizeTx(&tx, filter.OnlyShowGtid)
				callFn(tx)
			}
			return nil
		}
		if err != nil {
			return err
		}

		// GTID-only fast path
		if filter.OnlyShowGtid {
			if h.EventType != replication.GTID_EVENT && h.EventType != replication.ANONYMOUS_GTID_EVENT {
				if h.EventType == replication.FORMAT_DESCRIPTION_EVENT ||
					h.EventType == replication.TABLE_MAP_EVENT {
					body, err := readEventBody(r, h)
					if err != nil {
						return err
					}
					if _, err = parseEvent(parser, h, headBuf, body); err != nil {
						return err
					}
				} else {
					if err := skipEventBody(r, h); err != nil {
						return err
					}
				}
				continue
			}
			body, err := readEventBody(r, h)
			if err != nil {
				return err
			}
			e, err := parseEvent(parser, h, headBuf, body)
			if err != nil {
				return err
			}

			evs := ParseBinlogEvent(&replication.BinlogEvent{Header: h, Event: e})
			for _, ev := range evs {
				if ev.Type != "gtid" {
					continue
				}
				startPos := int(h.LogPos - h.EventSize)

				if filter.EndPos != 0 && startPos > filter.EndPos {
					continue
				}
				if filter.StartPos != 0 && startPos < filter.StartPos {
					continue
				}

				if currentGtid != "" {
					tx.EndPos = startPos - 1
					finalizeTx(&tx, true)
					if !callFn(tx) {
						return nil
					}
					if subGtid != nil {
						if err := subGtid.Sub(tx.GTID); err == nil && subGtid.EventCount() == 0 {
							return nil
						}
					}
					tx = Transaction{}
				}

				currentGtid = ev.Data

				if inGtid != nil {
					if c, _ := inGtid.Contain(ev.Data); !c {
						tx = Transaction{}
						currentGtid = ""
						continue
					}
				}
				if exGtid != nil {
					if c, _ := exGtid.Contain(ev.Data); c {
						currentGtid = ""
						tx = Transaction{}
						continue
					}
				}

				tx = Transaction{
					GTID:      ev.Data,
					StartPos:  startPos,
					EndPos:    startPos,
					Timestamp: int64(h.Timestamp),
				}
			}
			continue
		}

		// 先处理 GTID 事件（决定当前事务是否命中）
		if h.EventType == replication.GTID_EVENT || h.EventType == replication.ANONYMOUS_GTID_EVENT {
			body, err := readEventBody(r, h)
			if err != nil {
				return err
			}
			e, err := parseEvent(parser, h, headBuf, body)
			if err != nil {
				return err
			}

			evs := ParseBinlogEvent(&replication.BinlogEvent{Header: h, Event: e})
			for _, ev := range evs {
				if ev.Type != "gtid" {
					continue
				}
				startPos := int(h.LogPos - h.EventSize)

				if currentGtid != "" {
					finalizeTx(&tx, false)
					if !callFn(tx) {
						return nil
					}
					if subGtid != nil {
						if err := subGtid.Sub(tx.GTID); err == nil && subGtid.EventCount() == 0 {
							return nil
						}
					}
					tx = Transaction{}
				}

				currentGtid = ev.Data
				skipCurrentTxn = false

				if filter.EndPos != 0 && startPos > filter.EndPos {
					skipCurrentTxn = true
				}
				if filter.StartPos != 0 && startPos < filter.StartPos {
					skipCurrentTxn = true
				}
				if inGtid != nil {
					if c, _ := inGtid.Contain(ev.Data); !c {
						skipCurrentTxn = true
					}
				}
				if exGtid != nil {
					if c, _ := exGtid.Contain(ev.Data); c {
						skipCurrentTxn = true
					}
				}

				if !skipCurrentTxn {
					tx = Transaction{
						GTID:      ev.Data,
						StartPos:  startPos,
						Timestamp: int64(h.Timestamp),
						Txs:       make([]TxDetail, 0, 8),
						sqlOrigin: make([]string, 0, 4),
					}
				} else {
					tx = Transaction{}
				}
			}
			continue
		}

		// 未命中事务时，TABLE_MAP_EVENT 仍需解析（parser 缓存表元数据），
		// 其余事件可安全跳过
		if skipCurrentTxn {
			if h.EventType == replication.TABLE_MAP_EVENT ||
				h.EventType == replication.FORMAT_DESCRIPTION_EVENT {
				body, err := readEventBody(r, h)
				if err != nil {
					return err
				}
				if _, err = parseEvent(parser, h, headBuf, body); err != nil {
					return err
				}
			} else {
				if err := skipEventBody(r, h); err != nil {
					return err
				}
			}
			continue
		}

		body, err := readEventBody(r, h)
		if err != nil {
			return err
		}
		e, err := parseEvent(parser, h, headBuf, body)
		if err != nil {
			return err
		}

		if h.EventType == replication.TABLE_MAP_EVENT {
			tbMapPos = h.LogPos - h.EventSize
		}

		evs := ParseBinlogEvent(&replication.BinlogEvent{Header: h, Event: e})
		for _, ev := range evs {
			startPos := 0
			if ev.Type == "query" || ev.Type == "gtid" {
				startPos = int(h.LogPos - h.EventSize)
			} else {
				startPos = int(tbMapPos)
			}

			switch ev.Type {
			case "":
				tx.EndPos = int(h.LogPos)

			case "tablemap":
				tx.EndPos = int(h.LogPos)
				tbMapPos = h.LogPos - h.EventSize

			case "rowsquery":
				tx.EndPos = int(h.LogPos)
				tx.sqlOrigin = append(tx.sqlOrigin, ev.Data)

			default:
				tx.EndPos = int(h.LogPos)
				if ev.Type == "query" {
					if equalFoldShort(ev.Data, "begin") {
						if tx.TxStartTime == 0 {
							tx.TxStartTime = int64(h.Timestamp)
						}
						tx.Status = STATUS_BEGIN
					} else if equalFoldShort(ev.Data, "commit") {
						tx.Status = STATUS_COMMIT
						tx.TxEndTime = int64(h.Timestamp)
					} else if equalFoldShort(ev.Data, "rollback") {
						tx.Status = STATUS_ROLLBACK
						tx.TxEndTime = int64(h.Timestamp)
					}
				}
				if ev.DB != "" && ev.TB != "" {
					tx.dmlEventCount++
				}
				tx.Txs = append(tx.Txs, TxDetail{
					StartPos:           startPos,
					EndPos:             int(h.LogPos),
					Db:                 ev.DB,
					Table:              ev.TB,
					Sql:                ev.Data,
					SqlType:            ev.Type,
					Rows:               ev.Rows,
					ColumnTypes:        ev.ColumnTypes,
					ColumnCollationIDs: ev.ColumnCollationIDs,
					RowCount:           int(ev.RowCnt),
					Timestamp:          int64(h.Timestamp),
					CompressionType:    ev.CompressionType,
				})
			}
		}
	}
}

func selectVisibleTxDetails(tx Transaction, includeMatcher, excludeMatcher *tableMatcher, filter BinlogFilter) ([]TxDetail, bool, bool, bool) {
	txs := make([]TxDetail, 0, len(tx.Txs))
	matched := false

	for _, t := range tx.Txs {
		includeMatch := includeMatcher != nil && includeMatcher.match(t.Db, t.Table)
		excludeMatch := excludeMatcher != nil && excludeMatcher.match(t.Db, t.Table)

		if t.Db == "" && t.Table == "" {
			if includeMatcher != nil {
				if filter.IncludeBlank {
					matched = true
					if filter.PickTxAllIfMatch {
						return nil, true, true, false
					}
					txs = append(txs, t)
				}
				continue
			}

			if excludeMatcher != nil {
				if filter.ExcludeBlank {
					matched = true
					if filter.PickTxAllIfMatch {
						return nil, true, false, true
					}
					continue
				}
				txs = append(txs, t)
				continue
			}

			txs = append(txs, t)
			continue
		}

		if includeMatcher != nil {
			if includeMatch {
				matched = true
				if filter.PickTxAllIfMatch {
					return nil, true, true, false
				}
				txs = append(txs, t)
			}
			continue
		}

		if excludeMatcher != nil {
			if excludeMatch {
				matched = true
				if filter.PickTxAllIfMatch {
					return nil, true, false, true
				}
				continue
			}
			txs = append(txs, t)
			continue
		}

		txs = append(txs, t)
	}

	return txs, matched, false, false
}

func prepareTableMatchers(filter BinlogFilter) (includeMatcher, excludeMatcher *tableMatcher, err error) {
	if len(filter.IncludeTables) > 0 {
		includeMatcher, err = buildTableMatcher(filter.IncludeTables)
		if err != nil {
			return nil, nil, fmt.Errorf("invalid include-tables: %w", err)
		}
	}
	if len(filter.ExcludeTables) > 0 {
		excludeMatcher, err = buildTableMatcher(filter.ExcludeTables)
		if err != nil {
			return nil, nil, fmt.Errorf("invalid exclude-tables: %w", err)
		}
	}
	return includeMatcher, excludeMatcher, nil
}

func buildTableMatcher(patterns []string) (*tableMatcher, error) {
	m := &tableMatcher{
		exactMatch: make(map[string]bool),
		dbWildcard: make(map[string]bool),
		tbWildcard: make(map[string]bool),
	}

	for _, pattern := range patterns {
		origin := pattern
		pattern = strings.ToLower(strings.TrimSpace(pattern))
		if pattern == "" {
			continue
		}
		if pattern == "*.*" {
			m.matchAll = true
			continue
		}
		parts := strings.Split(pattern, ".")
		if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
			return nil, fmt.Errorf("invalid table pattern %q: expect db.table", strings.TrimSpace(origin))
		}
		db, tb := parts[0], parts[1]
		if db != "*" && strings.Contains(db, "*") {
			return nil, fmt.Errorf("invalid table pattern %q: wildcard '*' must occupy full db segment", strings.TrimSpace(origin))
		}
		if tb != "*" && strings.Contains(tb, "*") {
			return nil, fmt.Errorf("invalid table pattern %q: wildcard '*' must occupy full table segment", strings.TrimSpace(origin))
		}
		if db == "*" && tb == "*" {
			m.matchAll = true
		} else if db == "*" {
			m.tbWildcard[tb] = true
		} else if tb == "*" {
			m.dbWildcard[db] = true
		} else {
			m.exactMatch[db+"."+tb] = true
		}
	}
	return m, nil
}

func hasConfiguredTablePatterns(patterns []string) bool {
	for _, p := range patterns {
		if strings.TrimSpace(p) != "" {
			return true
		}
	}
	return false
}

func recomputeTxStatsFromVisibleDetails(tx *Transaction) {
	if tx == nil {
		return
	}
	if len(tx.Txs) == 0 {
		tx.RowsCount = 0
		tx.Size = 0
		return
	}

	firstSet := false
	minStart := 0
	maxEnd := 0
	rows := 0
	for _, d := range tx.Txs {
		rows += d.RowCount
		if !firstSet {
			minStart = d.StartPos
			maxEnd = d.EndPos
			firstSet = true
			continue
		}
		if d.StartPos < minStart {
			minStart = d.StartPos
		}
		if d.EndPos > maxEnd {
			maxEnd = d.EndPos
		}
	}

	tx.RowsCount = rows
	tx.StartPos = minStart
	tx.EndPos = maxEnd
	if maxEnd > minStart {
		tx.Size = maxEnd - minStart
	} else {
		tx.Size = 0
	}
}

func equalFoldShort(s, lower string) bool {
	if len(s) != len(lower) {
		return false
	}
	for i := 0; i < len(s); i++ {
		c := s[i]
		if 'A' <= c && c <= 'Z' {
			c += 'a' - 'A'
		}
		if c != lower[i] {
			return false
		}
	}
	return true
}