package store

import (
	"context"
	"database/sql"

	"github.com/jbub/pgbouncer_exporter/domain"
	"github.com/jmoiron/sqlx"
)

type stat struct {
	Database        string `db:"database"`
	TotalRequests   int64  `db:"total_requests"`
	TotalReceived   int64  `db:"total_received"`
	TotalSent       int64  `db:"total_sent"`
	TotalQueryTime  int64  `db:"total_query_time"`
	AverageRequests int64  `db:"avg_req"`
	AverageReceived int64  `db:"avg_recv"`
	AverageSent     int64  `db:"avg_sent"`
	AverageQuery    int64  `db:"avg_query"`
}

type pool struct {
	Database     string         `db:"database"`
	User         string         `db:"user"`
	Active       int64          `db:"cl_active"`
	Waiting      int64          `db:"cl_waiting"`
	ServerActive int64          `db:"sv_active"`
	ServerIdle   int64          `db:"sv_idle"`
	ServerUsed   int64          `db:"sv_used"`
	ServerTested int64          `db:"sv_tested"`
	ServerLogin  int64          `db:"sv_login"`
	MaxWait      int64          `db:"maxwait"`
	PoolMode     sql.NullString `db:"pool_mode"`
}

type database struct {
	Name               string         `db:"name"`
	Host               sql.NullString `db:"host"`
	Port               int64          `db:"port"`
	Database           string         `db:"database"`
	ForceUser          sql.NullString `db:"force_user"`
	PoolSize           int64          `db:"pool_size"`
	ReservePool        int64          `db:"reserve_pool"`
	PoolMode           sql.NullString `db:"pool_mode"`
	MaxConnections     int64          `db:"max_connections"`
	CurrentConnections int64          `db:"current_connections"`
}

type list struct {
	List  string `db:"list"`
	Items int64  `db:"items"`
}

// NewSQLStore returns new SQLStore.
func NewSQLStore(dataSource string) (*SQLStore, error) {
	db, err := sqlx.Connect("postgres", dataSource)
	if err != nil {
		return nil, err
	}
	return &SQLStore{db: db}, nil
}

// SQLStore is a sql based Store implementation.
type SQLStore struct {
	db *sqlx.DB
}

// GetStats returns stats.
func (s *SQLStore) GetStats(ctx context.Context) ([]domain.Stat, error) {
	var stats []stat
	if err := s.db.SelectContext(ctx, &stats, "SHOW STATS"); err != nil {
		return nil, err
	}
	var result []domain.Stat
	for _, row := range stats {
		result = append(result, domain.Stat(row))
	}
	return result, nil
}

// GetPools returns pools.
func (s *SQLStore) GetPools(ctx context.Context) ([]domain.Pool, error) {
	var pools []pool
	if err := s.db.SelectContext(ctx, &pools, "SHOW POOLS"); err != nil {
		return nil, err
	}
	var result []domain.Pool
	for _, row := range pools {
		result = append(result, domain.Pool{
			Database:     row.Database,
			User:         row.User,
			Active:       row.Active,
			Waiting:      row.Waiting,
			ServerActive: row.ServerActive,
			ServerIdle:   row.ServerIdle,
			ServerUsed:   row.ServerUsed,
			ServerTested: row.ServerTested,
			ServerLogin:  row.ServerLogin,
			MaxWait:      row.MaxWait,
			PoolMode:     row.PoolMode.String,
		})
	}
	return result, nil
}

// GetDatabases returns databases.
func (s *SQLStore) GetDatabases(ctx context.Context) ([]domain.Database, error) {
	var databases []database
	if err := s.db.SelectContext(ctx, &databases, "SHOW DATABASES"); err != nil {
		return nil, err
	}
	var result []domain.Database
	for _, row := range databases {
		result = append(result, domain.Database{
			Name:               row.Name,
			Host:               row.Host.String,
			Port:               row.Port,
			Database:           row.Database,
			ForceUser:          row.ForceUser.String,
			PoolSize:           row.PoolSize,
			ReservePool:        row.ReservePool,
			PoolMode:           row.PoolMode.String,
			MaxConnections:     row.MaxConnections,
			CurrentConnections: row.CurrentConnections,
		})
	}
	return result, nil
}

// GetLists returns lists.
func (s *SQLStore) GetLists(ctx context.Context) ([]domain.List, error) {
	var lists []list
	if err := s.db.SelectContext(ctx, &lists, "SHOW LISTS"); err != nil {
		return nil, err
	}
	var result []domain.List
	for _, row := range lists {
		result = append(result, domain.List(row))
	}
	return result, nil
}

// Close closes the store.
func (s *SQLStore) Close() error {
	if s.db != nil {
		return s.db.Close()
	}
	return nil
}