package sql

import (
	"database/sql"
	"fmt"
	"net"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/lib/pq"
	sqlite3 "github.com/mattn/go-sqlite3"

	"github.com/dexidp/dex/pkg/log"
	"github.com/dexidp/dex/storage"
)

const (
	// postgres error codes
	pgErrUniqueViolation = "23505" // unique_violation
)

// SQLite3 options for creating an SQL db.
type SQLite3 struct {
	// File to
	File string `json:"file"`
}

// Open creates a new storage implementation backed by SQLite3
func (s *SQLite3) Open(logger log.Logger) (storage.Storage, error) {
	conn, err := s.open(logger)
	if err != nil {
		return nil, err
	}
	return conn, nil
}

func (s *SQLite3) open(logger log.Logger) (*conn, error) {
	db, err := sql.Open("sqlite3", s.File)
	if err != nil {
		return nil, err
	}
	if s.File == ":memory:" {
		// sqlite3 uses file locks to coordinate concurrent access. In memory
		// doesn't support this, so limit the number of connections to 1.
		db.SetMaxOpenConns(1)
	}

	errCheck := func(err error) bool {
		sqlErr, ok := err.(sqlite3.Error)
		if !ok {
			return false
		}
		return sqlErr.ExtendedCode == sqlite3.ErrConstraintPrimaryKey
	}

	c := &conn{db, flavorSQLite3, logger, errCheck}
	if _, err := c.migrate(); err != nil {
		return nil, fmt.Errorf("failed to perform migrations: %v", err)
	}
	return c, nil
}

const (
	sslDisable    = "disable"
	sslRequire    = "require"
	sslVerifyCA   = "verify-ca"
	sslVerifyFull = "verify-full"
)

// PostgresSSL represents SSL options for Postgres databases.
type PostgresSSL struct {
	Mode   string
	CAFile string
	// Files for client auth.
	KeyFile  string
	CertFile string
}

// Postgres options for creating an SQL db.
type Postgres struct {
	Database string
	User     string
	Password string
	Host     string
	Port     uint16

	SSL PostgresSSL `json:"ssl" yaml:"ssl"`

	ConnectionTimeout int // Seconds

	// database/sql tunables, see
	// https://golang.org/pkg/database/sql/#DB.SetConnMaxLifetime and below
	// Note: defaults will be set if these are 0
	MaxOpenConns    int // default: 5
	MaxIdleConns    int // default: 5
	ConnMaxLifetime int // Seconds, default: not set
}

// Open creates a new storage implementation backed by Postgres.
func (p *Postgres) Open(logger log.Logger) (storage.Storage, error) {
	conn, err := p.open(logger, p.createDataSourceName())
	if err != nil {
		return nil, err
	}
	return conn, nil
}

var strEsc = regexp.MustCompile(`([\\'])`)

func dataSourceStr(str string) string {
	return "'" + strEsc.ReplaceAllString(str, `\$1`) + "'"
}

// createDataSourceName takes the configuration provided via the Postgres
// struct to create a data-source name that Go's database/sql package can
// make use of.
func (p *Postgres) createDataSourceName() string {
	parameters := []string{}

	addParam := func(key, val string) {
		parameters = append(parameters, fmt.Sprintf("%s=%s", key, val))
	}

	addParam("connect_timeout", strconv.Itoa(p.ConnectionTimeout))

	// detect host:port for backwards-compatibility
	host, port, err := net.SplitHostPort(p.Host)
	if err != nil {
		// not host:port, probably unix socket or bare address

		host = p.Host

		if p.Port != 0 {
			port = strconv.Itoa(int(p.Port))
		}
	}

	if host != "" {
		addParam("host", dataSourceStr(host))
	}

	if port != "" {
		addParam("port", port)
	}

	if p.User != "" {
		addParam("user", dataSourceStr(p.User))
	}

	if p.Password != "" {
		addParam("password", dataSourceStr(p.Password))
	}

	if p.Database != "" {
		addParam("dbname", dataSourceStr(p.Database))
	}

	if p.SSL.Mode == "" {
		// Assume the strictest mode if unspecified.
		addParam("sslmode", dataSourceStr(sslVerifyFull))
	} else {
		addParam("sslmode", dataSourceStr(p.SSL.Mode))
	}

	if p.SSL.CAFile != "" {
		addParam("sslrootcert", dataSourceStr(p.SSL.CAFile))
	}

	if p.SSL.CertFile != "" {
		addParam("sslcert", dataSourceStr(p.SSL.CertFile))
	}

	if p.SSL.KeyFile != "" {
		addParam("sslkey", dataSourceStr(p.SSL.KeyFile))
	}

	return strings.Join(parameters, " ")
}

func (p *Postgres) open(logger log.Logger, dataSourceName string) (*conn, error) {
	db, err := sql.Open("postgres", dataSourceName)
	if err != nil {
		return nil, err
	}

	// set database/sql tunables if configured
	if p.ConnMaxLifetime != 0 {
		db.SetConnMaxLifetime(time.Duration(p.ConnMaxLifetime) * time.Second)
	}

	if p.MaxIdleConns == 0 {
		db.SetMaxIdleConns(5)
	} else {
		db.SetMaxIdleConns(p.MaxIdleConns)
	}

	if p.MaxOpenConns == 0 {
		db.SetMaxOpenConns(5)
	} else {
		db.SetMaxOpenConns(p.MaxOpenConns)
	}

	errCheck := func(err error) bool {
		sqlErr, ok := err.(*pq.Error)
		if !ok {
			return false
		}
		return sqlErr.Code == pgErrUniqueViolation
	}

	c := &conn{db, flavorPostgres, logger, errCheck}
	if _, err := c.migrate(); err != nil {
		return nil, fmt.Errorf("failed to perform migrations: %v", err)
	}
	return c, nil
}