package main

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"time"

	_ "github.com/lib/pq"
)

type State struct {
	ID   int
	Name string
}

func (s State) MarshalJSON() ([]byte, error) {
	return json.Marshal(NewJSONState(s))
}

// func (s *State) UnmarshalJSON(data []byte) error {
// 	var js JSONState
// 	if err := json.Unmarshal(data, &js); err != nil {
// 		return err
// 	}
// 	*s = js.State()
// 	return nil
// }

type Park struct {
	ID          int
	Name        string
	Description string
	NearestCity string
	Visitors    int
	Established time.Time
	StateID     int
	State       State
}

func (p Park) MarshalJSON() ([]byte, error) {
	return json.Marshal(NewJSONPark(p))
}

type JSONState struct {
	ID   int    `json:"id"`
	Name string `json:"name"`
}

func (js JSONState) State() State {
	return State{
		js.ID,
		js.Name,
	}
}

func NewJSONState(state State) JSONState {
	return JSONState{
		state.ID,
		state.Name,
	}
}

type JSONPark struct {
	ID          int       `json:"id"`
	Name        string    `json:"name"`
	Description string    `json:"description"`
	NearestCity string    `json:"nearestCity"`
	Visitors    int       `json:"visitors"`
	Established time.Time `json:"establisheed"`
	StateID     int       `json:"stateID"`
	State       State
}

func NewJSONPark(park Park) JSONPark {
	return JSONPark{
		park.ID,
		park.Name,
		park.Description,
		park.NearestCity,
		park.Visitors,
		park.Established,
		park.StateID,
		park.State,
	}
}

func main() {

	const (
		host     = "172.17.0.2"
		port     = 5432
		user     = "postgres"
		password = "P@ssw0rd!"
		dbname   = "national_parks"
	)

	connectionString := fmt.Sprintf("host=%s port=%d user=%s password=%s dbname=%s sslmode=disable",
		host, port, user, password, dbname)

	db, err := sql.Open("postgres", connectionString)
	if err != nil {
		log.Fatal("DB Conn error: ", err)
	}

	if err = db.Ping(); err != nil {
		log.Fatal("DB Ping error: ", err)
	}
	defer db.Close()
	query := `
    Select
    p.id,
    p.name,
    p.description,
    p.nearest_city,
    p.visitors,
    p.established,
    p.state_id,
    s.id,
    s.name
    FROM parks as p
    LEFT OUTER JOIN states as s
    ON s.ID=p.state_id;`

	rows, err := db.Query(query)
	if err != nil {
		log.Fatal("DB Query error: ", err)
	}
	defer rows.Close()

	var parks []*Park
	for rows.Next() {
		var p = &Park{}
		if err := rows.Scan(
			&p.ID,
			&p.Name,
			&p.Description,
			&p.NearestCity,
			&p.Visitors,
			&p.Established,
			&p.StateID,
			&p.State.ID,
			&p.State.Name); err != nil {
			log.Fatal(err)
		}
		parks = append(parks, p)
	}

	jsonParks, err := json.Marshal(parks)
	if err != nil {
		panic(err)
	}
	fmt.Println(string(jsonParks))
}