package storage

import (
	"context"
	"database/sql"
	"fmt"

	"training-tracker/internal/models"
)

type ExerciseRepository struct {
	db *DB
}

func NewExerciseRepository(db *DB) *ExerciseRepository {
	return &ExerciseRepository{db: db}
}

func (r *ExerciseRepository) List(ctx context.Context) ([]models.Exercise, error) {
	query := `SELECT id, name, type, muscle_group, description, created_at
			  FROM exercises ORDER BY name`

	rows, err := r.db.QueryContext(ctx, query)
	if err != nil {
		return nil, fmt.Errorf("failed to query exercises: %w", err)
	}
	defer rows.Close()

	var exercises []models.Exercise
	for rows.Next() {
		var e models.Exercise
		var muscleGroup, description sql.NullString
		if err := rows.Scan(&e.ID, &e.Name, &e.Type, &muscleGroup, &description, &e.CreatedAt); err != nil {
			return nil, fmt.Errorf("failed to scan exercise: %w", err)
		}
		e.MuscleGroup = muscleGroup.String
		e.Description = description.String
		exercises = append(exercises, e)
	}

	return exercises, nil
}

func (r *ExerciseRepository) GetByID(ctx context.Context, id int64) (*models.Exercise, error) {
	query := `SELECT id, name, type, muscle_group, description, created_at
			  FROM exercises WHERE id = $1`

	var e models.Exercise
	var muscleGroup, description sql.NullString
	err := r.db.QueryRowContext(ctx, query, id).Scan(&e.ID, &e.Name, &e.Type, &muscleGroup, &description, &e.CreatedAt)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("failed to get exercise: %w", err)
	}
	e.MuscleGroup = muscleGroup.String
	e.Description = description.String

	return &e, nil
}

func (r *ExerciseRepository) Create(ctx context.Context, req *models.CreateExerciseRequest) (*models.Exercise, error) {
	query := `INSERT INTO exercises (name, type, muscle_group, description)
			  VALUES ($1, $2, $3, $4)
			  RETURNING id, name, type, muscle_group, description, created_at`

	var e models.Exercise
	var muscleGroup, description sql.NullString
	err := r.db.QueryRowContext(ctx, query, req.Name, req.Type, nullString(req.MuscleGroup), nullString(req.Description)).
		Scan(&e.ID, &e.Name, &e.Type, &muscleGroup, &description, &e.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to create exercise: %w", err)
	}
	e.MuscleGroup = muscleGroup.String
	e.Description = description.String

	return &e, nil
}

func (r *ExerciseRepository) Update(ctx context.Context, id int64, req *models.CreateExerciseRequest) (*models.Exercise, error) {
	query := `UPDATE exercises
			  SET name = $1, type = $2, muscle_group = $3, description = $4
			  WHERE id = $5
			  RETURNING id, name, type, muscle_group, description, created_at`

	var e models.Exercise
	var muscleGroup, description sql.NullString
	err := r.db.QueryRowContext(ctx, query, req.Name, req.Type, nullString(req.MuscleGroup), nullString(req.Description), id).
		Scan(&e.ID, &e.Name, &e.Type, &muscleGroup, &description, &e.CreatedAt)
	if err == sql.ErrNoRows {
		return nil, nil
	}
	if err != nil {
		return nil, fmt.Errorf("failed to update exercise: %w", err)
	}
	e.MuscleGroup = muscleGroup.String
	e.Description = description.String

	return &e, nil
}

func (r *ExerciseRepository) Delete(ctx context.Context, id int64) error {
	query := `DELETE FROM exercises WHERE id = $1`
	result, err := r.db.ExecContext(ctx, query, id)
	if err != nil {
		return fmt.Errorf("failed to delete exercise: %w", err)
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return sql.ErrNoRows
	}
	return nil
}

func nullString(s string) sql.NullString {
	if s == "" {
		return sql.NullString{}
	}
	return sql.NullString{String: s, Valid: true}
}