// Copyright 2022 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package schema

import (
	"fmt"
	"strings"

	"github.com/thoas/go-funk"
)

type colType int

const (
	Dinteger colType = iota
	Dboolean
	Dbigint
	Dnumeric
	Dbytea
	Dvarchar
	Dtext
)

type ConflictClause struct {
	Target []string
	Update []string
}

type Column struct {
	Name  string
	Type  colType
	Array bool
}
type Table struct {
	Name    string
	Columns []Column

	UpsertClause ConflictClause
}

type colfmt = func(interface{}) string

func (tbl *Table) ToCsvRow(args ...interface{}) []string {
	var row []string
	for i, col := range tbl.Columns {
		value := col.Type.formatter()(args[i])

		if col.Array {
			valueList := funk.Map(args[i], col.Type.formatter()).([]string)
			value = fmt.Sprintf("{%s}", strings.Join(valueList, ","))
		}

		row = append(row, value)
	}
	return row
}

func (tbl *Table) VarcharColumns() []string {
	columns := funk.Filter(tbl.Columns, func(col Column) bool {
		return col.Type == Dvarchar
	}).([]Column)

	columnNames := funk.Map(columns, func(col Column) string {
		return col.Name
	}).([]string)
	return columnNames
}

func OnConflict(target ...string) ConflictClause {
	return ConflictClause{Target: target}
}
func (c ConflictClause) Set(fields ...string) ConflictClause {
	c.Update = fields
	return c
}

// ToInsertStatement returns a Postgres-compatible SQL insert statement for the table
// using positional placeholders
func (tbl *Table) ToInsertStatement(upsert bool) string {
	var colnames, placeholders []string
	for i, col := range tbl.Columns {
		colnames = append(colnames, col.Name)
		placeholders = append(placeholders, fmt.Sprintf("$%d", i+1))
	}
	suffix := fmt.Sprintf("ON CONFLICT (%s)", strings.Join(tbl.UpsertClause.Target, ", "))
	if upsert && len(tbl.UpsertClause.Update) != 0 {
		var update_placeholders []string
		for _, name := range tbl.UpsertClause.Update {
			i := funk.IndexOf(tbl.Columns, func(col Column) bool { return col.Name == name })
			update_placeholders = append(update_placeholders, fmt.Sprintf("$%d", i+1))
		}
		suffix += fmt.Sprintf(
			" DO UPDATE SET (%s) = (%s)",
			strings.Join(tbl.UpsertClause.Update, ", "), strings.Join(update_placeholders, ", "),
		)
	} else {
		suffix += " DO NOTHING"
	}

	return fmt.Sprintf(
		"INSERT INTO %s (%s) VALUES (%s) %s",
		tbl.Name, strings.Join(colnames, ", "), strings.Join(placeholders, ", "), suffix,
	)
}

func sprintf(f string) colfmt {
	return func(x interface{}) string { return fmt.Sprintf(f, x) }
}

func (typ colType) formatter() colfmt {
	switch typ {
	case Dinteger:
		return sprintf("%d")
	case Dboolean:
		return func(x interface{}) string {
			if x.(bool) {
				return "t"
			}
			return "f"
		}
	case Dbigint:
		return sprintf("%s")
	case Dnumeric:
		return sprintf("%s")
	case Dbytea:
		return sprintf(`\x%x`)
	case Dvarchar:
		return sprintf("%s")
	case Dtext:
		return sprintf("%s")
	}
	panic("unreachable")
}