package models

import (
	"database/sql"
	"time"

	_ "github.com/lib/pq"
)

var db *sql.DB

type Measurement struct {
	CreatedAt time.Time
	Value     float32
}

func InitDB(dataSourceName string) (err error) {
	db, err = sql.Open("postgres", dataSourceName)
	if err != nil {
		return err
	}

	if err = db.Ping(); err != nil {
		return err
	}

	_, err = db.Exec(`
		CREATE TABLE IF NOT EXISTS measurements (
			created_at TIMESTAMP,
			value NUMERIC (3, 1)
		)
	`)
	return err
}

func AllMeasurements() (measurements []Measurement, err error) {
	rows, err := db.Query("SELECT * FROM measurements")
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	for rows.Next() {
		var measurement Measurement

		err = rows.Scan(&measurement.CreatedAt, &measurement.Value)
		if err != nil {
			return nil, err
		}

		measurements = append(measurements, measurement)
	}
	if err = rows.Err(); err != nil {
		return nil, err
	}

	return measurements, nil
}

func InsertMeasurement(value float64) (err error) {
	_, err = db.Exec(`
		INSERT INTO measurements VALUES (current_timestamp, $1)
	`, value)

	return err
}