package console

import (
	"errors"
	"fmt"
	"net"
	"net/http"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"akvorado/common/helpers"
)

// graphQuery describes the input for the /graph endpoint.
type graphQuery struct {
	Start      time.Time        `json:"start" binding:"required"`
	End        time.Time        `json:"end" binding:"required"`
	Points     int              `json:"points" binding:"required"` // minimum number of points
	Dimensions []graphColumn    `json:"dimensions"`                // group by ...
	Limit      int              `json:"limit"`                     // limit product of dimensions
	Filter     graphFilterGroup `json:"filter"`                    // where ...
}

type graphColumn int

const (
	graphColumnExporterAddress graphColumn = iota + 1
	graphColumnExporterName
	graphColumnExporterGroup
	graphColumnSrcAddr
	graphColumnDstAddr
	graphColumnSrcAS
	graphColumnDstAS
	graphColumnSrcCountry
	graphColumnDstCountry
	graphColumnInIfName
	graphColumnOutIfName
	graphColumnInIfDescription
	graphColumnOutIfDescription
	graphColumnInIfSpeed
	graphColumnOutIfSpeed
	graphColumnInIfConnectivity
	graphColumnOutIfConnectivity
	graphColumnInIfProvider
	graphColumnOutIfProvider
	graphColumnInIfBoundary
	graphColumnOutIfBoundary
	graphColumnEType
	graphColumnProto
	graphColumnSrcPort
	graphColumnDstPort
	graphColumnForwardingStatus
)

var graphColumnMap = helpers.NewBimap(map[graphColumn]string{
	graphColumnExporterAddress:   "ExporterAddress",
	graphColumnExporterName:      "ExporterName",
	graphColumnExporterGroup:     "ExporterGroup",
	graphColumnSrcAddr:           "SrcAddr",
	graphColumnDstAddr:           "DstAddr",
	graphColumnSrcAS:             "SrcAS",
	graphColumnDstAS:             "DstAS",
	graphColumnSrcCountry:        "SrcCountry",
	graphColumnDstCountry:        "DstCountry",
	graphColumnInIfName:          "InIfName",
	graphColumnOutIfName:         "OutIfName",
	graphColumnInIfDescription:   "InIfDescription",
	graphColumnOutIfDescription:  "OutIfDescription",
	graphColumnInIfSpeed:         "InIfSpeed",
	graphColumnOutIfSpeed:        "OutIfSpeed",
	graphColumnInIfConnectivity:  "InIfConnectivity",
	graphColumnOutIfConnectivity: "OutIfConnectivity",
	graphColumnInIfProvider:      "InIfProvider",
	graphColumnOutIfProvider:     "OutIfProvider",
	graphColumnInIfBoundary:      "InIfBoundary",
	graphColumnOutIfBoundary:     "OutIfBoundary",
	graphColumnEType:             "EType",
	graphColumnProto:             "Proto",
	graphColumnSrcPort:           "SrcPort",
	graphColumnDstPort:           "DstPort",
	graphColumnForwardingStatus:  "ForwardingStatus",
})

func (gc graphColumn) MarshalText() ([]byte, error) {
	got, ok := graphColumnMap.LoadValue(gc)
	if ok {
		return []byte(got), nil
	}
	return nil, errors.New("unknown group operator")
}
func (gc graphColumn) String() string {
	got, _ := graphColumnMap.LoadValue(gc)
	return got
}
func (gc *graphColumn) UnmarshalText(input []byte) error {
	got, ok := graphColumnMap.LoadKey(string(input))
	if ok {
		*gc = got
		return nil
	}
	return errors.New("unknown group operator")
}

type graphFilterGroup struct {
	Operator graphFilterGroupOperator `json:"operator" binding:"required"`
	Children []graphFilterGroup       `json:"children"`
	Rules    []graphFilterRule        `json:"rules"`
}

type graphFilterGroupOperator int

const (
	graphFilterGroupOperatorAny graphFilterGroupOperator = iota + 1
	graphFilterGroupOperatorAll
)

var graphFilterGroupOperatorMap = helpers.NewBimap(map[graphFilterGroupOperator]string{
	graphFilterGroupOperatorAny: "any",
	graphFilterGroupOperatorAll: "all",
})

func (gfgo graphFilterGroupOperator) MarshalText() ([]byte, error) {
	got, ok := graphFilterGroupOperatorMap.LoadValue(gfgo)
	if ok {
		return []byte(got), nil
	}
	return nil, errors.New("unknown group operator")
}
func (gfgo *graphFilterGroupOperator) UnmarshalText(input []byte) error {
	got, ok := graphFilterGroupOperatorMap.LoadKey(string(input))
	if ok {
		*gfgo = got
		return nil
	}
	return errors.New("unknown group operator")
}

type graphFilterRule struct {
	Column   graphColumn             `json:"column" binding:"required"`
	Operator graphFilterRuleOperator `json:"operator" binding:"required"`
	Value    string                  `json:"value" binding:"required"`
}

type graphFilterRuleOperator int

const (
	graphFilterRuleOperatorEqual graphFilterRuleOperator = iota + 1
	graphFilterRuleOperatorNotEqual
	graphFilterRuleOperatorLessThan
	graphFilterRuleOperatorGreaterThan
)

var graphFilterRuleOperatorMap = helpers.NewBimap(map[graphFilterRuleOperator]string{
	graphFilterRuleOperatorEqual:       "=",
	graphFilterRuleOperatorNotEqual:    "!=",
	graphFilterRuleOperatorLessThan:    "<",
	graphFilterRuleOperatorGreaterThan: ">",
})

func (gfro graphFilterRuleOperator) MarshalText() ([]byte, error) {
	got, ok := graphFilterRuleOperatorMap.LoadValue(gfro)
	if ok {
		return []byte(got), nil
	}
	return nil, errors.New("unknown rule operator")
}
func (gfro graphFilterRuleOperator) String() string {
	got, _ := graphFilterRuleOperatorMap.LoadValue(gfro)
	return got
}
func (gfro *graphFilterRuleOperator) UnmarshalText(input []byte) error {
	got, ok := graphFilterRuleOperatorMap.LoadKey(string(input))
	if ok {
		*gfro = got
		return nil
	}
	return errors.New("unknown rule operator")
}

// toSQLWhere translates a graphFilterGroup to SQL expression (to be used in WHERE)
func (gfg graphFilterGroup) toSQLWhere() (string, error) {
	operator := map[graphFilterGroupOperator]string{
		graphFilterGroupOperatorAll: " AND ",
		graphFilterGroupOperatorAny: " OR ",
	}[gfg.Operator]
	expressions := []string{}
	for _, expr := range gfg.Children {
		subexpr, err := expr.toSQLWhere()
		if err != nil {
			return "", err
		}
		expressions = append(expressions, fmt.Sprintf("(%s)", subexpr))
	}
	for _, expr := range gfg.Rules {
		subexpr, err := expr.toSQLWhere()
		if err != nil {
			return "", err
		}
		expressions = append(expressions, fmt.Sprintf("(%s)", subexpr))
	}
	return strings.Join(expressions, operator), nil
}

// toSQLWhere translates a graphFilterRule to an SQL expression (to be used in WHERE)
func (gfr graphFilterRule) toSQLWhere() (string, error) {
	quote := func(v string) string {
		return "'" + strings.NewReplacer(`\`, `\\`, `'`, `\'`).Replace(v) + "'"
	}
	switch gfr.Column {
	case graphColumnExporterAddress, graphColumnSrcAddr, graphColumnDstAddr:
		// IP
		ip := net.ParseIP(gfr.Value)
		if ip == nil {
			return "", fmt.Errorf("cannot parse IP %q for %s", gfr.Value, gfr.Column)
		}
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual:
			return fmt.Sprintf("%s %s IPv6StringToNum(%s)", gfr.Column, gfr.Operator, quote(ip.String())), nil
		}
	case graphColumnExporterName, graphColumnExporterGroup, graphColumnSrcCountry, graphColumnDstCountry, graphColumnInIfName, graphColumnOutIfName, graphColumnInIfDescription, graphColumnInIfConnectivity, graphColumnOutIfConnectivity, graphColumnInIfProvider, graphColumnOutIfProvider:
		// String
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual:
			return fmt.Sprintf("%s %s %s", gfr.Column, gfr.Operator, quote(gfr.Value)), nil
		}
	case graphColumnInIfBoundary, graphColumnOutIfBoundary:
		// Boundary
		switch gfr.Value {
		case "external", "internal":
		default:
			return "", fmt.Errorf("cannot parse boundary %q for %s", gfr.Value, gfr.Column)
		}
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual:
			return fmt.Sprintf("%s %s %s", gfr.Column, gfr.Operator, quote(gfr.Value)), nil
		}
	case graphColumnInIfSpeed, graphColumnOutIfSpeed, graphColumnForwardingStatus:
		// Integer (64 bit)
		value, err := strconv.ParseUint(gfr.Value, 10, 64)
		if err != nil {
			return "", fmt.Errorf("cannot parse int %q for %s", gfr.Value, gfr.Column)
		}
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual, graphFilterRuleOperatorLessThan, graphFilterRuleOperatorGreaterThan:
			return fmt.Sprintf("%s %s %d", gfr.Column, gfr.Operator, value), nil
		}
	case graphColumnSrcPort, graphColumnDstPort:
		// Port
		port, err := strconv.ParseUint(gfr.Value, 10, 16)
		if err != nil {
			return "", fmt.Errorf("cannot parse port %q for %s", gfr.Value, gfr.Column)
		}
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual, graphFilterRuleOperatorLessThan, graphFilterRuleOperatorGreaterThan:
			return fmt.Sprintf("%s %s %d", gfr.Column, gfr.Operator, port), nil
		}
	case graphColumnSrcAS, graphColumnDstAS:
		// AS number
		value := strings.TrimPrefix(gfr.Value, "AS")
		asn, err := strconv.ParseUint(value, 10, 32)
		if err != nil {
			return "", fmt.Errorf("cannot parse AS %q for %s", gfr.Value, gfr.Column)
		}
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual, graphFilterRuleOperatorLessThan, graphFilterRuleOperatorGreaterThan:
			return fmt.Sprintf("%s %s %d", gfr.Column, gfr.Operator, asn), nil
		}
	case graphColumnEType:
		// Ethernet Type
		etypes := map[string]uint16{
			"ipv4": 0x0800,
			"ipv6": 0x86dd,
		}
		etype, ok := etypes[strings.ToLower(gfr.Value)]
		if !ok {
			return "", fmt.Errorf("cannot parse etype %q for %s", gfr.Value, gfr.Column)
		}
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual:
			return fmt.Sprintf("%s %s %d", gfr.Column, gfr.Operator, etype), nil
		}
	case graphColumnProto:
		// Protocol
		// Case 1: int
		proto, err := strconv.ParseUint(gfr.Value, 10, 8)
		if err == nil {
			switch gfr.Operator {
			case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual, graphFilterRuleOperatorLessThan, graphFilterRuleOperatorGreaterThan:
				return fmt.Sprintf("%s %s %d", gfr.Column, gfr.Operator, proto), nil
			}
			break
		}
		// Case 2: string
		switch gfr.Operator {
		case graphFilterRuleOperatorEqual, graphFilterRuleOperatorNotEqual:
			return fmt.Sprintf("dictGetOrDefault('protocols', 'name', Proto, '???') %s %s",
				gfr.Operator, quote(gfr.Value)), nil
		}
	}

	return "", fmt.Errorf("operator %s not supported for %s", gfr.Operator, gfr.Column)
}

// toSQLSelect transforms a column into an expression to use in SELECT
func (gc graphColumn) toSQLSelect() string {
	var strValue string
	switch gc {
	case graphColumnExporterAddress, graphColumnSrcAddr, graphColumnDstAddr:
		strValue = fmt.Sprintf("IPv6NumToString(%s)", gc)
	case graphColumnSrcAS, graphColumnDstAS:
		strValue = fmt.Sprintf(`concat(toString(%s), ': ', dictGetOrDefault('asns', 'name', %s, '???'))`,
			gc, gc)
	case graphColumnEType:
		strValue = `if(EType = 0x800, 'IPv4', if(EType = 0x86dd, 'IPv6', '???'))`
	case graphColumnProto:
		strValue = `dictGetOrDefault('protocols', 'name', Proto, '???')`
	case graphColumnInIfSpeed, graphColumnOutIfSpeed, graphColumnSrcPort, graphColumnDstPort, graphColumnForwardingStatus:
		strValue = fmt.Sprintf("toString(%s)", gc)
	default:
		strValue = gc.String()
	}
	return strValue
}

// graphQueryToSQL converts a graph query to an SQL request
func (query graphQuery) toSQL() (string, error) {
	interval := int64((query.End.Sub(query.Start).Seconds())) / int64(query.Points)

	// Filter
	where, err := query.Filter.toSQLWhere()
	if err != nil {
		return "", err
	}
	if where == "" {
		where = "{timefilter}"
	} else {
		where = fmt.Sprintf("{timefilter} AND (%s)", where)
	}

	// Select
	fields := []string{
		`toStartOfInterval(TimeReceived, INTERVAL slot second) AS time`,
		`SUM(Bytes*SamplingRate*8/slot) AS bps`,
	}
	selectFields := []string{}
	dimensions := []string{}
	others := []string{}
	for _, column := range query.Dimensions {
		field := column.toSQLSelect()
		selectFields = append(selectFields, field)
		dimensions = append(dimensions, column.String())
		others = append(others, "'Other'")
	}
	if len(dimensions) > 0 {
		fields = append(fields, fmt.Sprintf(`if((%s) IN rows, [%s], [%s]) AS dimensions`,
			strings.Join(dimensions, ", "),
			strings.Join(selectFields, ", "),
			strings.Join(others, ", ")))
	} else {
		fields = append(fields, "emptyArrayString() AS dimensions")
	}

	// With
	with := []string{fmt.Sprintf(`intDiv(%d, {resolution})*{resolution} AS slot`, interval)}
	if len(dimensions) > 0 {
		with = append(with, fmt.Sprintf(
			"rows AS (SELECT %s FROM {table} WHERE %s GROUP BY %s ORDER BY SUM(Bytes) DESC LIMIT %d)",
			strings.Join(dimensions, ", "),
			where,
			strings.Join(dimensions, ", "),
			query.Limit))
	}

	sqlQuery := fmt.Sprintf(`
WITH
 %s
SELECT
 %s
FROM {table}
WHERE %s
GROUP BY time, dimensions
ORDER BY time`, strings.Join(with, ",\n "), strings.Join(fields, ",\n "), where)
	return sqlQuery, nil
}

type graphHandlerOutput struct {
	Rows    [][]string  `json:"rows"`
	Time    []time.Time `json:"t"`
	Points  [][]int     `json:"points"`  // t → row → bps
	Average []int       `json:"average"` // row → bps
	Min     []int       `json:"min"`
	Max     []int       `json:"max"`
}

func (c *Component) graphHandlerFunc(gc *gin.Context) {
	ctx := c.t.Context(gc.Request.Context())
	var query graphQuery
	if err := gc.ShouldBindJSON(&query); err != nil {
		gc.JSON(http.StatusBadRequest, gin.H{"message": err.Error()})
		return
	}
	if query.Start.After(query.End) {
		gc.JSON(http.StatusBadRequest, gin.H{"message": "start should not be after end"})
		return
	}
	if query.Points < 5 || query.Points > 2000 {
		gc.JSON(http.StatusBadRequest, gin.H{"message": "points should be >= 5 and <= 2000"})
		return
	}
	if query.Limit == 0 {
		query.Limit = 10
	}
	if query.Limit < 5 || query.Limit > 50 {
		gc.JSON(http.StatusBadRequest, gin.H{"message": "limit should be >= 5 and <= 50"})
		return
	}

	sqlQuery, err := query.toSQL()
	if err != nil {
		gc.JSON(http.StatusBadRequest, gin.H{"message": err.Error()})
		return
	}
	resolution := time.Duration(int64(query.End.Sub(query.Start).Nanoseconds()) / int64(query.Points))
	if resolution < time.Second {
		resolution = time.Second
	}
	sqlQuery = c.queryFlowsTable(sqlQuery,
		query.Start, query.End, resolution)
	gc.Header("X-SQL-Query", sqlQuery)

	results := []struct {
		Time       time.Time `ch:"time"`
		Bps        float64   `ch:"bps"`
		Dimensions []string  `ch:"dimensions"`
	}{}
	if err := c.d.ClickHouseDB.Conn.Select(ctx, &results, sqlQuery); err != nil {
		c.r.Err(err).Msg("unable to query database")
		gc.JSON(http.StatusInternalServerError, gin.H{"message": "Unable to query database."})
		return
	}

	// We want to sort rows depending on how much data they gather each
	output := graphHandlerOutput{
		Time: []time.Time{},
	}
	rowValues := map[string][]int{}  // values for each row (indexed by internal key)
	rowKeys := map[string][]string{} // mapping from keys to dimensions
	rowSums := map[string]uint64{}   // sum for a given row (to sort)
	lastTime := time.Time{}
	for _, result := range results {
		if result.Time != lastTime {
			output.Time = append(output.Time, result.Time)
			lastTime = result.Time
		}
	}
	lastTime = time.Time{}
	idx := -1
	for _, result := range results {
		if result.Time != lastTime {
			idx++
			lastTime = result.Time
		}
		rowKey := fmt.Sprintf("%s", result.Dimensions)
		row, ok := rowValues[rowKey]
		if !ok {
			rowKeys[rowKey] = result.Dimensions
			row = make([]int, len(output.Time))
			rowValues[rowKey] = row
		}
		rowValues[rowKey][idx] = int(result.Bps)
		sum, _ := rowSums[rowKey]
		rowSums[rowKey] = sum + uint64(result.Bps)
	}
	rows := make([]string, len(rowKeys))
	i := 0
	for k := range rowKeys {
		rows[i] = k
		i++
	}
	// Sort by sum, except we want "Other" to be last
	sort.Slice(rows, func(i, j int) bool {
		if rowKeys[rows[i]][0] == "Other" {
			return false
		}
		if rowKeys[rows[j]][0] == "Other" {
			return true
		}
		return rowSums[rows[i]] > rowSums[rows[j]]
	})
	output.Rows = make([][]string, len(rows))
	output.Points = make([][]int, len(rows))
	output.Average = make([]int, len(rows))
	output.Min = make([]int, len(rows))
	output.Max = make([]int, len(rows))

	for idx, r := range rows {
		output.Rows[idx] = rowKeys[r]
		output.Points[idx] = rowValues[r]
		output.Average[idx] = int(rowSums[r] / uint64(len(output.Time)))
		for j, v := range rowValues[r] {
			if j == 0 || output.Min[idx] > v {
				output.Min[idx] = v
			}
			if j == 0 || output.Max[idx] < v {
				output.Max[idx] = v
			}
		}
	}

	gc.JSON(http.StatusOK, output)
}