package schedule

import (
	"database/sql"
	"errors"
	"fmt"
	"time"
)

type Schedule struct {
	ID          int64     `json:"id"`
	VolunteerID int64     `json:"volunteer_id"`
	Title       string    `json:"title"`
	StartsAt    time.Time `json:"starts_at"`
	EndsAt      time.Time `json:"ends_at"`
	Notes       string    `json:"notes,omitempty"`
	CreatedAt   time.Time `json:"created_at"`
	UpdatedAt   time.Time `json:"updated_at"`
}

type CreateInput struct {
	VolunteerID int64  `json:"volunteer_id"`
	Title       string `json:"title"`
	StartsAt    string `json:"starts_at"`
	EndsAt      string `json:"ends_at"`
	Notes       string `json:"notes"`
}

type UpdateInput struct {
	Title    *string `json:"title"`
	StartsAt *string `json:"starts_at"`
	EndsAt   *string `json:"ends_at"`
	Notes    *string `json:"notes"`
}

const timeLayout = "2006-01-02T15:04:05Z"

type Store struct {
	db *sql.DB
}

func NewStore(db *sql.DB) *Store {
	return &Store{db: db}
}

func (s *Store) Create(in CreateInput) (*Schedule, error) {
	res, err := s.db.Exec(
		`INSERT INTO schedules (volunteer_id, title, starts_at, ends_at, notes) VALUES (?, ?, ?, ?, ?)`,
		in.VolunteerID, in.Title, in.StartsAt, in.EndsAt, in.Notes,
	)
	if err != nil {
		return nil, fmt.Errorf("insert schedule: %w", err)
	}
	id, _ := res.LastInsertId()
	return s.GetByID(id)
}

func (s *Store) GetByID(id int64) (*Schedule, error) {
	sc := &Schedule{}
	var startsAt, endsAt, createdAt, updatedAt string
	var notes sql.NullString
	err := s.db.QueryRow(
		`SELECT id, volunteer_id, title, starts_at, ends_at, notes, created_at, updated_at FROM schedules WHERE id = ?`, id,
	).Scan(&sc.ID, &sc.VolunteerID, &sc.Title, &startsAt, &endsAt, &notes, &createdAt, &updatedAt)
	if errors.Is(err, sql.ErrNoRows) {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("get schedule: %w", err)
	}
	sc.StartsAt, _ = time.Parse("2006-01-02 15:04:05", startsAt)
	sc.EndsAt, _ = time.Parse("2006-01-02 15:04:05", endsAt)
	sc.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
	sc.UpdatedAt, _ = time.Parse("2006-01-02 15:04:05", updatedAt)
	if notes.Valid {
		sc.Notes = notes.String
	}
	return sc, nil
}

func (s *Store) List(volunteerID int64) ([]Schedule, error) {
	query := `SELECT id, volunteer_id, title, starts_at, ends_at, notes, created_at, updated_at FROM schedules`
	args := []any{}
	if volunteerID > 0 {
		query += ` WHERE volunteer_id = ?`
		args = append(args, volunteerID)
	}
	query += ` ORDER BY starts_at`

	rows, err := s.db.Query(query, args...)
	if err != nil {
		return nil, fmt.Errorf("list schedules: %w", err)
	}
	defer rows.Close()

	var schedules []Schedule
	for rows.Next() {
		var sc Schedule
		var startsAt, endsAt, createdAt, updatedAt string
		var notes sql.NullString
		if err := rows.Scan(&sc.ID, &sc.VolunteerID, &sc.Title, &startsAt, &endsAt, &notes, &createdAt, &updatedAt); err != nil {
			return nil, err
		}
		sc.StartsAt, _ = time.Parse("2006-01-02 15:04:05", startsAt)
		sc.EndsAt, _ = time.Parse("2006-01-02 15:04:05", endsAt)
		sc.CreatedAt, _ = time.Parse("2006-01-02 15:04:05", createdAt)
		sc.UpdatedAt, _ = time.Parse("2006-01-02 15:04:05", updatedAt)
		if notes.Valid {
			sc.Notes = notes.String
		}
		schedules = append(schedules, sc)
	}
	return schedules, rows.Err()
}

func (s *Store) Update(id int64, in UpdateInput) (*Schedule, error) {
	sc, err := s.GetByID(id)
	if err != nil || sc == nil {
		return sc, err
	}
	title := sc.Title
	startsAt := sc.StartsAt.Format("2006-01-02 15:04:05")
	endsAt := sc.EndsAt.Format("2006-01-02 15:04:05")
	notes := sc.Notes

	if in.Title != nil {
		title = *in.Title
	}
	if in.StartsAt != nil {
		startsAt = *in.StartsAt
	}
	if in.EndsAt != nil {
		endsAt = *in.EndsAt
	}
	if in.Notes != nil {
		notes = *in.Notes
	}
	_, err = s.db.Exec(
		`UPDATE schedules SET title=?, starts_at=?, ends_at=?, notes=?, updated_at=datetime('now') WHERE id=?`,
		title, startsAt, endsAt, notes, id,
	)
	if err != nil {
		return nil, fmt.Errorf("update schedule: %w", err)
	}
	return s.GetByID(id)
}

func (s *Store) Delete(id int64) error {
	_, err := s.db.Exec(`DELETE FROM schedules WHERE id = ?`, id)
	return err
}