// Copyright 2012, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package tabletserver

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"strings"

	"code.google.com/p/vitess/go/relog"
	"code.google.com/p/vitess/go/sqltypes"
	"code.google.com/p/vitess/go/vt/schema"
)

// buildValueList builds the set of PK reference rows used to drive the next query.
// It is uses the PK values supplied in the original query and bind variables.
// The generated reference rows are validated for type match against the PK of the table.
func buildValueList(tableInfo *TableInfo, pkValues []interface{}, bindVars map[string]interface{}) [][]sqltypes.Value {
	length := -1
	for _, pkValue := range pkValues {
		if list, ok := pkValue.([]interface{}); ok {
			if length == -1 {
				if length = len(list); length == 0 {
					panic(NewTabletError(FAIL, "empty list for values %v", pkValues))
				}
			} else if length != len(list) {
				panic(NewTabletError(FAIL, "mismatched lengths for values %v", pkValues))
			}
		}
	}
	if length == -1 {
		length = 1
	}
	valueList := make([][]sqltypes.Value, length)
	for i := 0; i < length; i++ {
		valueList[i] = make([]sqltypes.Value, len(pkValues))
		for j, pkValue := range pkValues {
			if list, ok := pkValue.([]interface{}); ok {
				valueList[i][j] = resolveValue(tableInfo.GetPKColumn(j), list[i], bindVars)
			} else {
				valueList[i][j] = resolveValue(tableInfo.GetPKColumn(j), pkValue, bindVars)
			}
		}
	}
	return valueList
}

// buildSecondaryList is used for handling ON DUPLICATE DMLs, or those that change the PK.
func buildSecondaryList(tableInfo *TableInfo, pkList [][]sqltypes.Value, secondaryList []interface{}, bindVars map[string]interface{}) [][]sqltypes.Value {
	if secondaryList == nil {
		return nil
	}
	valueList := make([][]sqltypes.Value, len(pkList))
	for i, row := range pkList {
		valueList[i] = make([]sqltypes.Value, len(row))
		for j, cell := range row {
			if secondaryList[j] == nil {
				valueList[i][j] = cell
			} else {
				valueList[i][j] = resolveValue(tableInfo.GetPKColumn(j), secondaryList[j], bindVars)
			}
		}
	}
	return valueList
}

func resolveValue(col *schema.TableColumn, value interface{}, bindVars map[string]interface{}) (result sqltypes.Value) {
	switch v := value.(type) {
	case string:
		lookup, ok := bindVars[v[1:]]
		if !ok {
			panic(NewTabletError(FAIL, "Missing bind var %s", v))
		}
		sqlval, err := sqltypes.BuildValue(lookup)
		if err != nil {
			panic(NewTabletError(FAIL, "%v", err))
		}
		result = sqlval
	case sqltypes.Value:
		result = v
	case nil:
		// no op
	default:
		panic("unreachable")
	}
	validateValue(col, result)
	return result
}

func validateRow(tableInfo *TableInfo, columnNumbers []int, row []sqltypes.Value) {
	if len(row) != len(columnNumbers) {
		panic(NewTabletError(FAIL, "data inconsistency %d vs %d", len(row), len(columnNumbers)))
	}
	for j, value := range row {
		validateValue(&tableInfo.Columns[columnNumbers[j]], value)
	}
}

func validateValue(col *schema.TableColumn, value sqltypes.Value) {
	if value.IsNull() {
		return
	}
	switch col.Category {
	case schema.CAT_NUMBER:
		if !value.IsNumeric() {
			panic(NewTabletError(FAIL, "Type mismatch, expecting numeric type for %v", value))
		}
	case schema.CAT_VARBINARY:
		if !value.IsString() {
			panic(NewTabletError(FAIL, "Type mismatch, expecting string type for %v", value))
		}
	}
}

func buildKey(tableInfo *TableInfo, row []sqltypes.Value) (key string) {
	buf := bytes.NewBuffer(make([]byte, 0, 32))
	for i, pkValue := range row {
		if pkValue.IsNull() {
			return ""
		}
		pkValue.EncodeAscii(buf)
		if i != len(row)-1 {
			buf.WriteByte('.')
		}
	}
	return buf.String()
}

func buildStreamComment(tableInfo *TableInfo, pkValueList [][]sqltypes.Value, secondaryList [][]sqltypes.Value) []byte {
	buf := bytes.NewBuffer(make([]byte, 0, 256))
	fmt.Fprintf(buf, " /* _stream %s (", tableInfo.Name)
	// We assume the first index exists, and is the pk
	for _, pkName := range tableInfo.Indexes[0].Columns {
		buf.WriteString(pkName)
		buf.WriteString(" ")
	}
	buf.WriteString(")")
	buildPKValueList(buf, tableInfo, pkValueList)
	buildPKValueList(buf, tableInfo, secondaryList)
	buf.WriteString("; */")
	return buf.Bytes()
}

func buildPKValueList(buf *bytes.Buffer, tableInfo *TableInfo, pkValueList [][]sqltypes.Value) {
	for _, pkValues := range pkValueList {
		buf.WriteString(" (")
		for _, pkValue := range pkValues {
			pkValue.EncodeAscii(buf)
			buf.WriteString(" ")
		}
		buf.WriteString(")")
	}
}

func applyFilter(columnNumbers []int, input []sqltypes.Value) (output []sqltypes.Value) {
	output = make([]sqltypes.Value, len(columnNumbers))
	for colIndex, colPointer := range columnNumbers {
		if colPointer >= 0 {
			output[colIndex] = input[colPointer]
		}
	}
	return output
}

func applyFilterWithPKDefaults(tableInfo *TableInfo, columnNumbers []int, input []sqltypes.Value) (output []sqltypes.Value) {
	output = make([]sqltypes.Value, len(columnNumbers))
	for colIndex, colPointer := range columnNumbers {
		if colPointer >= 0 {
			output[colIndex] = input[colPointer]
		} else {
			output[colIndex] = tableInfo.GetPKColumn(colIndex).Default
		}
	}
	return output
}

func validateKey(tableInfo *TableInfo, key string) (newKey string) {
	if key == "" {
		// TODO: Verify auto-increment table
		return
	}
	pieces := strings.Split(key, ".")
	if len(pieces) != len(tableInfo.PKColumns) {
		// TODO: Verify auto-increment table
		return ""
	}
	pkValues := make([]sqltypes.Value, len(tableInfo.PKColumns))
	for i, piece := range pieces {
		if piece[0] == '\'' {
			s, err := base64.StdEncoding.DecodeString(piece[1 : len(piece)-1])
			if err != nil {
				relog.Warning("Error decoding key %s for table %s: %v", key, tableInfo.Name, err)
				return
			}
			pkValues[i] = sqltypes.MakeString(s)
		} else if piece == "null" {
			// TODO: Verify auto-increment table
			return ""
		} else {
			n, err := sqltypes.BuildNumeric(piece)
			if err != nil {
				relog.Warning("Error decoding key %s for table %s: %v", key, tableInfo.Name, err)
				return
			}
			pkValues[i] = n
		}
	}
	if newKey = buildKey(tableInfo, pkValues); newKey != key {
		relog.Warning("Error: Key mismatch, received: %s, computed: %s", key, newKey)
	}
	return buildKey(tableInfo, pkValues)
}