package db

import (
	"context"
)

const classTemplateColumns = "id, tenant_id, title, duration_minutes, capacity, created_at"
const classSessionColumns = "cs.id, cs.tenant_id, cs.template_id, cs.location_id, ct.title, cs.starts_at, cs.ends_at, cs.capacity"

func (r *PGRepository) ListClassTemplatesByTenant(ctx context.Context, tenantID string) ([]ClassTemplateRecord, error) {
	rows, err := r.pool.Query(ctx, `
		SELECT `+classTemplateColumns+`
		FROM class_templates
		WHERE tenant_id = $1
		ORDER BY created_at ASC
	`, tenantID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var records []ClassTemplateRecord
	for rows.Next() {
		var record ClassTemplateRecord
		if err := rows.Scan(
			&record.ID,
			&record.TenantID,
			&record.Title,
			&record.DurationMinutes,
			&record.Capacity,
			&record.CreatedAt,
		); err != nil {
			return nil, err
		}
		records = append(records, record)
	}
	return records, rows.Err()
}

func (r *PGRepository) GetClassTemplateByID(ctx context.Context, templateID string) (ClassTemplateRecord, error) {
	var record ClassTemplateRecord
	err := r.pool.QueryRow(ctx, `
		SELECT `+classTemplateColumns+`
		FROM class_templates
		WHERE id = $1
	`, templateID).Scan(
		&record.ID,
		&record.TenantID,
		&record.Title,
		&record.DurationMinutes,
		&record.Capacity,
		&record.CreatedAt,
	)
	return record, err
}

func (r *PGRepository) CreateClassTemplate(ctx context.Context, params CreateClassTemplateParams) (ClassTemplateRecord, error) {
	var record ClassTemplateRecord
	err := r.pool.QueryRow(ctx, `
		INSERT INTO class_templates (tenant_id, title, duration_minutes, capacity)
		VALUES ($1, $2, $3, $4)
		RETURNING `+classTemplateColumns+`
	`, params.TenantID, params.Title, params.DurationMinutes, params.Capacity).Scan(
		&record.ID,
		&record.TenantID,
		&record.Title,
		&record.DurationMinutes,
		&record.Capacity,
		&record.CreatedAt,
	)
	return record, err
}

func (r *PGRepository) UpdateClassTemplate(ctx context.Context, templateID string, params CreateClassTemplateParams) (ClassTemplateRecord, error) {
	var record ClassTemplateRecord
	err := r.pool.QueryRow(ctx, `
		UPDATE class_templates
		SET title = $2, duration_minutes = $3, capacity = $4
		WHERE id = $1
		RETURNING `+classTemplateColumns+`
	`, templateID, params.Title, params.DurationMinutes, params.Capacity).Scan(
		&record.ID,
		&record.TenantID,
		&record.Title,
		&record.DurationMinutes,
		&record.Capacity,
		&record.CreatedAt,
	)
	return record, err
}

func (r *PGRepository) DeleteClassTemplate(ctx context.Context, templateID string) error {
	_, err := r.pool.Exec(ctx, `DELETE FROM class_templates WHERE id = $1`, templateID)
	return err
}

func (r *PGRepository) GetClassSessionByID(ctx context.Context, sessionID string) (ClassSessionRecord, error) {
	var record ClassSessionRecord
	err := r.pool.QueryRow(ctx, `
		SELECT `+classSessionColumns+`
		FROM class_sessions cs
		INNER JOIN class_templates ct ON ct.id = cs.template_id
		WHERE cs.id = $1
	`, sessionID).Scan(
		&record.ID,
		&record.TenantID,
		&record.TemplateID,
		&record.LocationID,
		&record.Title,
		&record.StartsAt,
		&record.EndsAt,
		&record.Capacity,
	)
	return record, err
}

func (r *PGRepository) CreateClassSession(ctx context.Context, params CreateClassSessionParams) (ClassSessionRecord, error) {
	var record ClassSessionRecord
	err := r.pool.QueryRow(ctx, `
		INSERT INTO class_sessions (tenant_id, template_id, location_id, starts_at, ends_at, capacity)
		VALUES ($1, $2, $3, $4, $5, $6)
		RETURNING id
	`, params.TenantID, params.TemplateID, params.LocationID, params.StartsAt, params.EndsAt, params.Capacity).Scan(&record.ID)
	if err != nil {
		return record, err
	}
	return r.GetClassSessionByID(ctx, record.ID)
}

func (r *PGRepository) DeleteClassSession(ctx context.Context, sessionID string) error {
	_, err := r.pool.Exec(ctx, `DELETE FROM class_sessions WHERE id = $1`, sessionID)
	return err
}