package main

import (
	"database/sql"
	"encoding/json"
	"errors"
	_ "github.com/lib/pq"
	"log"
	"os"
	"time"
)

type DB struct {
	database *sql.DB
}

func InitDatabase() *DB {
	if os.Getenv("PGUSER") == "" {
		os.Setenv("PGUSER", "levyraati")
	}
	if os.Getenv("PGDATABASE") == "" {
		os.Setenv("PGDATABASE", "levyraati")
	}

	connStr := "sslmode=disable"
	var err error
	database, err := sql.Open("postgres", connStr)
	if err != nil {
		log.Fatal(err)
	}
	_, err = database.Query("SELECT 1")
	if err != nil {
		log.Fatal(err)
	}
	return &DB{database}
}

func (db *DB) FindUserBySpotifyID(username string) (string, error) {
	var user string
	err := db.database.QueryRow("SELECT u.username FROM public.user u WHERE u.spotify_id = $1", username).Scan(&user)
	return user, err
}

func (db *DB) FindHashForUser(username string) (string, error) {
	var hash string
	err := db.database.QueryRow("SELECT u.password FROM public.user u WHERE lower(u.username) = lower($1)", username).Scan(&hash)
	return hash, err
}

func (db *DB) EntrySynced(userId, roundId int) (bool, error) {
	query := `UPDATE public.entry SET synced = true WHERE user_id = $1 AND round_id = $2`
	res, err := db.database.Exec(query, userId, roundId)

	if err != nil {
		return false, err
	}

	affected, err := res.RowsAffected()
	if err != nil {
		return false, err
	}

	if affected != 1 {
		return false, errors.New("Unknown entry ID")
	}
	return true, nil

}

func (db *DB) FindEntriesToSync() ([]*EntryToSync, error) {
	query := `
	SELECT e.user_id, e.round_id, e.artist, e.title, e.spotify_url, p.article, u.username, r.section
	FROM public.entry e 
	JOIN public."user" u ON u.id = e.user_id
	JOIN public.round r ON r.id = e.round_id
	JOIN public.panel p ON p.id = r.panel_id
	WHERE r.start < current_timestamp AND e.synced = false AND p.sync_enabled = true`
	rows, err := db.database.Query(query)

	if err != nil {
		log.Println("Error while reading songs from database:", err)
		return nil, err
	}
	defer rows.Close()
	var entries []*EntryToSync
	for rows.Next() {
		var (
			userId, roundId                                       int
			artist, title, spotifyURL, article, username, section string
		)
		err := rows.Scan(&userId, &roundId, &artist, &title, &spotifyURL, &article, &username, &section)
		if err != nil {
			log.Println("Error while scanning row:", err)
			return nil, err
		}
		entries = append(entries, &EntryToSync{userId, roundId, artist, title, spotifyURL, article, username, section})
	}
	err = rows.Err()
	if err != nil {
		log.Println("Error after reading cursor:", err)
		return nil, err
	}
	return entries, nil
}

type EntryToSync struct {
	userId, roundId                                       int
	artist, title, spotifyURL, article, username, section string
}

func (db *DB) FindRoundInfo(roundNum int) (*RoundInfo, error) {
	query := `
		SELECT r.section, p.name, p.article, r.start, r.end
		FROM public.round r
                JOIN public.panel p ON p.id = r.panel_id
		WHERE r.id = $1`
	rows, err := db.database.Query(query, roundNum)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var (
		section, panelName, panelArticle string
		start, end                       *time.Time
	)
	if !rows.Next() {
		return nil, nil
	}
	err = rows.Scan(&section, &panelName, &panelArticle, &start, &end)
	if err != nil {
		log.Println("Error while scanning row:", err)
		return nil, err
	}
	return &RoundInfo{section, panelName, panelArticle, start, end}, nil
}

type RoundInfo struct {
	Section, PanelName, PanelArticle string
	Start, End                       *time.Time
}

func (db *DB) FindAllRoundEntries(round int) ([]*Song, error) {
	query := `
		SELECT r.id, r.section, e.artist, e.title, e.spotify_url, e.synced, u.username
		FROM public.round r
                JOIN public.panel p ON p.id = r.panel_id
		JOIN public.entry e ON r.id = e.round_id
		JOIN public."user" u ON u.id = e.user_id
		WHERE r.id = $1`
	rows, err := db.database.Query(query, round)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return db.rowsToSong(rows)
}

func (db *DB) FindAllEntries(username string) ([]*Song, error) {
	query := `
		SELECT r.id, r.section, e.artist, e.title, e.spotify_url, e.synced, u.username
		FROM public.round r
		LEFT JOIN public.entry e ON r.id = e.round_id AND e.user_id = 
                  (SELECT u2.id FROM public."user" u2 WHERE lower(u2.username) = lower($1))
		LEFT JOIN public."user" u ON r.id = e.round_id AND u.id = e.user_id
		ORDER BY r.start ASC`
	rows, err := db.database.Query(query, username)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	return db.rowsToSong(rows)
}

func (db *DB) rowsToSong(rows *sql.Rows) ([]*Song, error) {
	var songs []*Song
	for i := 0; rows.Next(); i++ {
		song := &Song{}
		songs = append(songs, song)
		var (
			artist, title, url, username *string
			sync                         *bool
		)
		err := rows.Scan(&songs[i].RoundID, &songs[i].RoundName, &artist, &title, &url, &sync, &username)
		if err != nil {
			return nil, err
		}
		if artist != nil {
			song.Artist = *artist
		}
		if title != nil {
			song.Title = *title
		}
		if url != nil {
			song.URL = *url
		}
		if sync != nil {
			song.Sync = *sync
		}
		if username != nil {
			song.Submitter = *username
		}
	}
	return songs, nil
}

type Song struct {
	RoundID   int
	RoundName string
	Title     string
	Artist    string
	URL       string
	Sync      bool
	Submitter string
}

func (db *DB) UpdateEntry(username, round, artist, title, url string) (bool, error) {
	query := `
	INSERT INTO public.entry
	SELECT id, $2, $3, $4, $5, false
	FROM public."user" u
	WHERE lower(u.username) = lower($1)
	ON CONFLICT (user_id, round_id) DO UPDATE SET artist = EXCLUDED.artist, title = EXCLUDED.title, spotify_url = EXCLUDED.spotify_url, synced = EXCLUDED.synced`
	res, err := db.database.Exec(query, username, round, artist, title, url)

	if err != nil {
		return false, err
	}
	affected, err := res.RowsAffected()
	if err != nil {
		return false, err
	}
	if affected != 1 {
		return false, nil
	}
	return true, nil
}

func (db *DB) FindAllPanels() ([]string, error) {
	query := `
	SELECT name FROM public.panel`
	rows, err := db.database.Query(query)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	names := make([]string, 0)
	for i := 0; rows.Next(); i++ {
		var name string
		err := rows.Scan(&name)
		if err != nil {
			return nil, err
		}
		names = append(names, name)
	}
	return names, nil
}

func (db *DB) FindPlaylistBySection(sectionName string) ([]string, error) {
	query := `
	SELECT array_to_json(pl.tracks) FROM public.round_playlist pl
	JOIN public.round r ON pl.round_id = r.id
	WHERE r.section = $1`
	row := db.database.QueryRow(query, sectionName)
	var tracksJson []byte
	tracks := make([]string, 0)
	err := row.Scan(&tracksJson)
	if err != nil {
		return nil, err
	}
	err = json.Unmarshal(tracksJson, &tracks)
	if err != nil {
		return nil, err
	}
	return tracks, nil
}

func (db *DB) UpdatePlaylistBySection(sectionName string, tracks []string) (bool, error) {
	tracksJSON, err := json.Marshal(tracks)
	if err != nil {
		return false, err
	}
	query := `
	INSERT INTO public.round_playlist
	SELECT r.id, ARRAY(SELECT e::text FROM json_array_elements_text($2::json) e)
	FROM public.round r 
	WHERE r.section = $1
	ON CONFLICT (round_id) DO UPDATE SET tracks = EXCLUDED.tracks`

	res, err := db.database.Exec(query, sectionName, tracksJSON)

	if err != nil {
		return false, err
	}
	affected, err := res.RowsAffected()
	if err != nil {
		return false, err
	}
	if affected != 1 {
		return false, nil
	}
	return true, nil
}