package storage

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

	"training-tracker/internal/models"
)

type PlanRepository struct {
	db *DB
}

func NewPlanRepository(db *DB) *PlanRepository {
	return &PlanRepository{db: db}
}

func (r *PlanRepository) List(ctx context.Context) ([]models.TrainingPlan, error) {
	query := `SELECT id, name, description, created_at FROM training_plans ORDER BY name`

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

	var plans []models.TrainingPlan
	for rows.Next() {
		var p models.TrainingPlan
		var description sql.NullString
		if err := rows.Scan(&p.ID, &p.Name, &description, &p.CreatedAt); err != nil {
			return nil, fmt.Errorf("failed to scan plan: %w", err)
		}
		p.Description = description.String
		plans = append(plans, p)
	}

	return plans, nil
}

func (r *PlanRepository) GetByID(ctx context.Context, id int64) (*models.TrainingPlan, error) {
	query := `SELECT id, name, description, created_at FROM training_plans WHERE id = $1`

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

	exerciseQuery := `
		SELECT pe.id, pe.plan_id, pe.exercise_id, pe.sets, pe.reps, pe.duration, pe.sort_order,
			   e.id, e.name, e.type, e.muscle_group, e.description, e.created_at
		FROM plan_exercises pe
		JOIN exercises e ON pe.exercise_id = e.id
		WHERE pe.plan_id = $1
		ORDER BY pe.sort_order`

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

	for rows.Next() {
		var pe models.PlanExercise
		var sets, reps, duration sql.NullInt64
		var muscleGroup, exerciseDesc sql.NullString
		if err := rows.Scan(
			&pe.ID, &pe.PlanID, &pe.ExerciseID, &sets, &reps, &duration, &pe.Order,
			&pe.Exercise.ID, &pe.Exercise.Name, &pe.Exercise.Type, &muscleGroup, &exerciseDesc, &pe.Exercise.CreatedAt,
		); err != nil {
			return nil, fmt.Errorf("failed to scan plan exercise: %w", err)
		}
		pe.Sets = int(sets.Int64)
		pe.Reps = int(reps.Int64)
		pe.Duration = int(duration.Int64)
		pe.Exercise.MuscleGroup = muscleGroup.String
		pe.Exercise.Description = exerciseDesc.String
		p.Exercises = append(p.Exercises, pe)
	}

	return &p, nil
}

func (r *PlanRepository) Create(ctx context.Context, req *models.CreatePlanRequest) (*models.TrainingPlan, error) {
	tx, err := r.db.BeginTx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	query := `INSERT INTO training_plans (name, description)
			  VALUES ($1, $2)
			  RETURNING id, name, description, created_at`

	var p models.TrainingPlan
	var description sql.NullString
	err = tx.QueryRowContext(ctx, query, req.Name, nullString(req.Description)).
		Scan(&p.ID, &p.Name, &description, &p.CreatedAt)
	if err != nil {
		return nil, fmt.Errorf("failed to create plan: %w", err)
	}
	p.Description = description.String

	for _, pe := range req.Exercises {
		exerciseQuery := `INSERT INTO plan_exercises (plan_id, exercise_id, sets, reps, duration, sort_order)
						  VALUES ($1, $2, $3, $4, $5, $6)`
		_, err = tx.ExecContext(ctx, exerciseQuery, p.ID, pe.ExerciseID, nullInt(pe.Sets), nullInt(pe.Reps), nullInt(pe.Duration), pe.Order)
		if err != nil {
			return nil, fmt.Errorf("failed to create plan exercise: %w", err)
		}
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("failed to commit transaction: %w", err)
	}

	return r.GetByID(ctx, p.ID)
}

func (r *PlanRepository) Update(ctx context.Context, id int64, req *models.CreatePlanRequest) (*models.TrainingPlan, error) {
	tx, err := r.db.BeginTx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("failed to begin transaction: %w", err)
	}
	defer tx.Rollback()

	query := `UPDATE training_plans SET name = $1, description = $2 WHERE id = $3`
	result, err := tx.ExecContext(ctx, query, req.Name, nullString(req.Description), id)
	if err != nil {
		return nil, fmt.Errorf("failed to update plan: %w", err)
	}
	rows, _ := result.RowsAffected()
	if rows == 0 {
		return nil, nil
	}

	_, err = tx.ExecContext(ctx, `DELETE FROM plan_exercises WHERE plan_id = $1`, id)
	if err != nil {
		return nil, fmt.Errorf("failed to delete plan exercises: %w", err)
	}

	for _, pe := range req.Exercises {
		exerciseQuery := `INSERT INTO plan_exercises (plan_id, exercise_id, sets, reps, duration, sort_order)
						  VALUES ($1, $2, $3, $4, $5, $6)`
		_, err = tx.ExecContext(ctx, exerciseQuery, id, pe.ExerciseID, nullInt(pe.Sets), nullInt(pe.Reps), nullInt(pe.Duration), pe.Order)
		if err != nil {
			return nil, fmt.Errorf("failed to create plan exercise: %w", err)
		}
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("failed to commit transaction: %w", err)
	}

	return r.GetByID(ctx, id)
}

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

func nullInt(i int) sql.NullInt64 {
	if i == 0 {
		return sql.NullInt64{}
	}
	return sql.NullInt64{Int64: int64(i), Valid: true}
}