package store

import (
	"database/sql"
	"fmt"
	"path/filepath"
	"time"

	_ "modernc.org/sqlite"
)

type Store struct {
	db *sql.DB
}

const schema = `
CREATE TABLE IF NOT EXISTS rsvps (
	id INTEGER PRIMARY KEY AUTOINCREMENT,
	message TEXT,
	attending INTEGER NOT NULL DEFAULT 1,
	created_at DATETIME NOT NULL
);

CREATE TABLE IF NOT EXISTS rsvp_guests (
	id INTEGER PRIMARY KEY AUTOINCREMENT,
	rsvp_id INTEGER NOT NULL REFERENCES rsvps(id),
	name TEXT NOT NULL,
	is_child INTEGER NOT NULL DEFAULT 0
);

CREATE TABLE IF NOT EXISTS photo_uploads (
	id INTEGER PRIMARY KEY AUTOINCREMENT,
	name TEXT NOT NULL,
	message TEXT,
	email TEXT,
	phone TEXT,
	created_at DATETIME NOT NULL
);

CREATE TABLE IF NOT EXISTS photo_files (
	id INTEGER PRIMARY KEY AUTOINCREMENT,
	upload_id INTEGER NOT NULL REFERENCES photo_uploads(id),
	filename TEXT NOT NULL,
	path TEXT NOT NULL,
	url TEXT NOT NULL,
	created_at DATETIME NOT NULL
);
`

func Open(dataDir string) (*Store, error) {
	dbPath := filepath.Join(dataDir, "rsvp.db")
	db, err := sql.Open("sqlite", dbPath)
	if err != nil {
		return nil, fmt.Errorf("opening database: %w", err)
	}
	// SQLite only supports one writer at a time; a single connection avoids
	// SQLITE_BUSY errors under concurrent requests instead of retry logic.
	db.SetMaxOpenConns(1)

	if _, err := db.Exec(schema); err != nil {
		db.Close()
		return nil, fmt.Errorf("migrating schema: %w", err)
	}
	// Backfill columns on databases created before they existed; SQLite has no
	// "ADD COLUMN IF NOT EXISTS", so a duplicate-column error here is expected.
	db.Exec(`ALTER TABLE rsvps ADD COLUMN attending INTEGER NOT NULL DEFAULT 1`)

	return &Store{db: db}, nil
}

func (s *Store) Close() error {
	return s.db.Close()
}

type Guest struct {
	ID      int64
	Name    string
	IsChild bool
}

type RSVP struct {
	Guests    []Guest
	Message   string
	Attending bool
}

// ListGuests returns every RSVP'd guest, ordered by submission then entry order.
func (s *Store) ListGuests() ([]Guest, error) {
	rows, err := s.db.Query(
		`SELECT g.name, g.is_child
		 FROM rsvp_guests g
		 JOIN rsvps r ON r.id = g.rsvp_id
		 WHERE r.attending <> 0
		 ORDER BY r.created_at ASC, g.id ASC`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var guests []Guest
	for rows.Next() {
		var g Guest
		if err := rows.Scan(&g.Name, &g.IsChild); err != nil {
			return nil, err
		}
		guests = append(guests, g)
	}
	return guests, rows.Err()
}

type RSVPRecord struct {
	ID        int64
	Message   string
	Attending bool
	CreatedAt time.Time
	Guests    []Guest
}

// ListRSVPs returns every RSVP submission (not flattened per-guest), oldest first.
func (s *Store) ListRSVPs() ([]RSVPRecord, error) {
	rows, err := s.db.Query(
		`SELECT r.id, r.message, r.attending, r.created_at, g.id, g.name, g.is_child
		 FROM rsvps r
		 LEFT JOIN rsvp_guests g ON g.rsvp_id = r.id
		 ORDER BY r.created_at ASC, r.id ASC, g.id ASC`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []RSVPRecord
	index := map[int64]int{}
	for rows.Next() {
		var id int64
		var message string
		var attending bool
		var createdAt time.Time
		var guestID sql.NullInt64
		var name sql.NullString
		var isChild sql.NullBool
		if err := rows.Scan(&id, &message, &attending, &createdAt, &guestID, &name, &isChild); err != nil {
			return nil, err
		}

		i, ok := index[id]
		if !ok {
			out = append(out, RSVPRecord{ID: id, Message: message, Attending: attending, CreatedAt: createdAt})
			i = len(out) - 1
			index[id] = i
		}
		if name.Valid {
			out[i].Guests = append(out[i].Guests, Guest{ID: guestID.Int64, Name: name.String, IsChild: isChild.Bool})
		}
	}
	return out, rows.Err()
}

// DeleteRSVP removes an RSVP submission and its guests.
func (s *Store) DeleteRSVP(id int64) error {
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	if _, err := tx.Exec(`DELETE FROM rsvp_guests WHERE rsvp_id = ?`, id); err != nil {
		return err
	}
	res, err := tx.Exec(`DELETE FROM rsvps WHERE id = ?`, id)
	if err != nil {
		return err
	}
	n, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if n == 0 {
		return fmt.Errorf("rsvp %d not found", id)
	}
	return tx.Commit()
}

func (s *Store) InsertRSVP(r RSVP) error {
	_, err := s.CreateRSVP(r)
	return err
}

// CreateRSVP inserts an RSVP and its guests, returning the new RSVP id.
func (s *Store) CreateRSVP(r RSVP) (int64, error) {
	tx, err := s.db.Begin()
	if err != nil {
		return 0, err
	}
	defer tx.Rollback()

	res, err := tx.Exec(
		`INSERT INTO rsvps (message, attending, created_at) VALUES (?, ?, ?)`,
		r.Message, r.Attending, time.Now().UTC(),
	)
	if err != nil {
		return 0, err
	}
	rsvpID, err := res.LastInsertId()
	if err != nil {
		return 0, err
	}

	for _, guest := range r.Guests {
		if _, err := tx.Exec(
			`INSERT INTO rsvp_guests (rsvp_id, name, is_child) VALUES (?, ?, ?)`,
			rsvpID, guest.Name, guest.IsChild,
		); err != nil {
			return 0, err
		}
	}

	return rsvpID, tx.Commit()
}

// SetRSVPAttending flips the attendance flag on one RSVP.
func (s *Store) SetRSVPAttending(id int64, attending bool) error {
	return s.mustAffectOne(`UPDATE rsvps SET attending = ? WHERE id = ?`, "rsvp", id, attending, id)
}

// UpdateGuest renames a guest line and sets its child flag.
func (s *Store) UpdateGuest(id int64, name string, isChild bool) error {
	return s.mustAffectOne(`UPDATE rsvp_guests SET name = ?, is_child = ? WHERE id = ?`, "guest", id, name, isChild, id)
}

// AddGuest appends a guest to an existing RSVP and returns the new guest id.
func (s *Store) AddGuest(rsvpID int64, g Guest) (int64, error) {
	var exists int
	if err := s.db.QueryRow(`SELECT 1 FROM rsvps WHERE id = ?`, rsvpID).Scan(&exists); err != nil {
		if err == sql.ErrNoRows {
			return 0, fmt.Errorf("rsvp %d not found", rsvpID)
		}
		return 0, err
	}
	res, err := s.db.Exec(
		`INSERT INTO rsvp_guests (rsvp_id, name, is_child) VALUES (?, ?, ?)`,
		rsvpID, g.Name, g.IsChild,
	)
	if err != nil {
		return 0, err
	}
	return res.LastInsertId()
}

// DeleteGuest removes one guest line, and its parent RSVP if it was the last one.
func (s *Store) DeleteGuest(id int64) error {
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	var rsvpID int64
	if err := tx.QueryRow(`SELECT rsvp_id FROM rsvp_guests WHERE id = ?`, id).Scan(&rsvpID); err != nil {
		if err == sql.ErrNoRows {
			return fmt.Errorf("guest %d not found", id)
		}
		return err
	}
	if _, err := tx.Exec(`DELETE FROM rsvp_guests WHERE id = ?`, id); err != nil {
		return err
	}
	var remaining int
	if err := tx.QueryRow(`SELECT COUNT(*) FROM rsvp_guests WHERE rsvp_id = ?`, rsvpID).Scan(&remaining); err != nil {
		return err
	}
	if remaining == 0 {
		if _, err := tx.Exec(`DELETE FROM rsvps WHERE id = ?`, rsvpID); err != nil {
			return err
		}
	}
	return tx.Commit()
}

func (s *Store) mustAffectOne(query, label string, id int64, args ...any) error {
	res, err := s.db.Exec(query, args...)
	if err != nil {
		return err
	}
	n, err := res.RowsAffected()
	if err != nil {
		return err
	}
	if n == 0 {
		return fmt.Errorf("%s %d not found", label, id)
	}
	return nil
}

type PhotoFile struct {
	Filename string
	Path     string
	URL      string
}

type PhotoUpload struct {
	Name    string
	Message string
	Email   string
	Phone   string
}

// CreatePhotoUpload inserts the upload record and returns its id, which the
// caller uses as the on-disk directory name before attaching files.
func (s *Store) CreatePhotoUpload(u PhotoUpload) (int64, error) {
	res, err := s.db.Exec(
		`INSERT INTO photo_uploads (name, message, email, phone, created_at) VALUES (?, ?, ?, ?, ?)`,
		u.Name, u.Message, u.Email, u.Phone, time.Now().UTC(),
	)
	if err != nil {
		return 0, err
	}
	return res.LastInsertId()
}

type PhotoFileRecord struct {
	URL          string
	UploaderName string
}

// ListPhotoFiles returns every uploaded photo, most recent first.
func (s *Store) ListPhotoFiles() ([]PhotoFileRecord, error) {
	rows, err := s.db.Query(
		`SELECT f.url, u.name
		 FROM photo_files f
		 JOIN photo_uploads u ON u.id = f.upload_id
		 ORDER BY f.created_at DESC, f.id DESC
		 LIMIT 200`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []PhotoFileRecord
	for rows.Next() {
		var rec PhotoFileRecord
		if err := rows.Scan(&rec.URL, &rec.UploaderName); err != nil {
			return nil, err
		}
		out = append(out, rec)
	}
	return out, rows.Err()
}

type PhotoUploadRecord struct {
	ID        int64
	Name      string
	Message   string
	CreatedAt time.Time
	Files     []PhotoFile
}

// ListPhotoUploads returns every upload submission (not flattened per-file), oldest first.
func (s *Store) ListPhotoUploads() ([]PhotoUploadRecord, error) {
	rows, err := s.db.Query(
		`SELECT u.id, u.name, u.message, u.created_at, f.filename, f.path, f.url
		 FROM photo_uploads u
		 LEFT JOIN photo_files f ON f.upload_id = u.id
		 ORDER BY u.created_at ASC, u.id ASC, f.id ASC`,
	)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var out []PhotoUploadRecord
	index := map[int64]int{}
	for rows.Next() {
		var id int64
		var name, message string
		var createdAt time.Time
		var filename, path, url sql.NullString
		if err := rows.Scan(&id, &name, &message, &createdAt, &filename, &path, &url); err != nil {
			return nil, err
		}

		i, ok := index[id]
		if !ok {
			out = append(out, PhotoUploadRecord{ID: id, Name: name, Message: message, CreatedAt: createdAt})
			i = len(out) - 1
			index[id] = i
		}
		if filename.Valid {
			out[i].Files = append(out[i].Files, PhotoFile{Filename: filename.String, Path: path.String, URL: url.String})
		}
	}
	return out, rows.Err()
}

// DeletePhotoUpload removes an upload's DB rows and returns the files it had,
// so the caller can also remove them from disk.
func (s *Store) DeletePhotoUpload(id int64) ([]PhotoFile, error) {
	tx, err := s.db.Begin()
	if err != nil {
		return nil, err
	}
	defer tx.Rollback()

	rows, err := tx.Query(`SELECT filename, path, url FROM photo_files WHERE upload_id = ?`, id)
	if err != nil {
		return nil, err
	}
	var files []PhotoFile
	for rows.Next() {
		var f PhotoFile
		if err := rows.Scan(&f.Filename, &f.Path, &f.URL); err != nil {
			rows.Close()
			return nil, err
		}
		files = append(files, f)
	}
	rows.Close()
	if err := rows.Err(); err != nil {
		return nil, err
	}

	if _, err := tx.Exec(`DELETE FROM photo_files WHERE upload_id = ?`, id); err != nil {
		return nil, err
	}
	res, err := tx.Exec(`DELETE FROM photo_uploads WHERE id = ?`, id)
	if err != nil {
		return nil, err
	}
	n, err := res.RowsAffected()
	if err != nil {
		return nil, err
	}
	if n == 0 {
		return nil, fmt.Errorf("photo upload %d not found", id)
	}
	if err := tx.Commit(); err != nil {
		return nil, err
	}
	return files, nil
}

func (s *Store) AddPhotoFiles(uploadID int64, files []PhotoFile) error {
	tx, err := s.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()

	now := time.Now().UTC()
	for _, f := range files {
		if _, err := tx.Exec(
			`INSERT INTO photo_files (upload_id, filename, path, url, created_at) VALUES (?, ?, ?, ?, ?)`,
			uploadID, f.Filename, f.Path, f.URL, now,
		); err != nil {
			return err
		}
	}
	return tx.Commit()
}