package main

import (
	"database/sql"
	"log"
	"time"
)

// TagClass : holds information about a specific TagClass
type TagClass struct {
	ID          int       `json:"id"`
	ClassType   string    `json:"classType"`
	Description string    `json:"description"`
	CreatedAt   time.Time `json:"createdAt"`
	UpdatedAt   time.Time `json:"updatedAt"`
}

// TagClasses : a list of TagClass items
type TagClasses []TagClass

const tagClassTableCreationQuery = `CREATE TABLE IF NOT EXISTS tagClasses (
	id int(10) unsigned AUTO_INCREMENT,
	classType varchar(255),
	description varchar(255),
	createdAt datetime,
	updatedAt datetime,
	UNIQUE KEY classType (classType),
	PRIMARY KEY (id)
  )`

func ensureTagClassTableExists(db *sql.DB) {
	if _, err := db.Exec(tagClassTableCreationQuery); err != nil {
		log.Fatal(err)
	}
}

func seedTagClassData(db *sql.DB) {
	sqlQuery := `INSERT INTO tagClasses VALUES 
	(1,'normal','Historical Data','2016-10-13 15:05:32','2016-10-13 15:05:32'),
	(2,'handshake','PLC Handshake','2016-10-13 15:05:32','2016-10-13 15:05:32');`
	insStmt, insErr := db.Prepare(sqlQuery)

	if insErr != nil {
		panic(insErr.Error()) // proper error handling instead of panic in your app
	}
	defer insStmt.Close() // Close the statement when we leave main() / the program terminates

	insStmt.Exec()
}

// getTagClass : used during GET command
func (c *TagClass) getTagClass(db *sql.DB) error {
	return db.QueryRow("SELECT classType, description, createdAt, updatedAt FROM tagClasses WHERE id=?", c.ID).Scan(&c.ClassType, &c.Description, &c.CreatedAt, &c.UpdatedAt)
}

// updateTagClass : used during PUT command
func (c *TagClass) updateTagClass(db *sql.DB) error {
	updStmt, updErr := db.Prepare("UPDATE tagClasses SET classType=?, description=?, updatedAt=? WHERE id=?")
	if updErr != nil {
		panic(updErr.Error()) // proper error handling instead of panic in your app
	}
	defer updStmt.Close() // Close the statement when we leave main() / the program terminates

	_, err := updStmt.Exec(c.ClassType, c.Description, time.Now(), c.ID)
	return err
}

// deleteTagClass : used during DELETE command
func (c *TagClass) deleteTagClass(db *sql.DB) error {
	_, err := db.Exec("DELETE FROM tagClasses WHERE id=?", c.ID)
	return err
}

// createTagClass : used during PUSH command
func (c *TagClass) createTagClass(db *sql.DB) error {
	stmtIns, insErr := db.Prepare("INSERT INTO tagClasses (classType, description, createdAt, updatedAt) VALUES (?, ?, ?, ?);")
	if insErr != nil {
		panic(insErr.Error()) // proper error handling instead of panic in your app
	}
	defer stmtIns.Close() // Close the statement when we leave main() / the program terminates

	_, err := stmtIns.Exec(c.ClassType, c.Description, time.Now(), time.Now())
	return err
}

// getTagClasses : used during GET command for all
func getTagClasses(db *sql.DB, start, count int) (TagClasses, error) {
	rows, err := db.Query(
		"SELECT id, classType, description, createdAt, updatedAt FROM tagClasses LIMIT ? OFFSET ?",
		count, start)

	if err != nil {
		return nil, err
	}

	defer rows.Close()

	tagClasses := TagClasses{}

	for rows.Next() {
		var c TagClass
		if err := rows.Scan(&c.ID, &c.ClassType, &c.Description, &c.CreatedAt, &c.UpdatedAt); err != nil {
			return nil, err
		}
		tagClasses = append(tagClasses, c)
	}

	return tagClasses, nil
}