package abac

import (
	"database/sql"

	"github.com/google/uuid"
	_ "github.com/mattn/go-sqlite3"
)

type SQLiteStore struct {
	db *sql.DB
}

func NewSQLiteStore(dbPath string) (*SQLiteStore, error) {
	db, err := sql.Open("sqlite3", dbPath)
	if err != nil {
		return nil, err
	}

	store := &SQLiteStore{db: db}
	err = store.createTables(db)
	if err != nil {
		return nil, err
	}

	return store, nil
}

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

func (s *SQLiteStore) GetUserAttributes(userID string) ([]Attribute, error) {
	rows, err := s.db.Query(`
		SELECT a.key, a.value
		FROM attributes a
		JOIN user_attributes ua ON a.id = ua.attribute_id
		WHERE ua.user_id = ?;
	`, userID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var attributes []Attribute

	for rows.Next() {
		var attribute Attribute
		err := rows.Scan(&attribute.Key, &attribute.Value)
		if err != nil {
			return nil, err
		}

		attributes = append(attributes, attribute)
	}

	return attributes, nil
}

func (s *SQLiteStore) GetResourceAttributes(resourceID string) ([]Attribute, error) {
	rows, err := s.db.Query(`
		SELECT a.key, a.value
		FROM attributes a
		JOIN resource_attributes ra ON a.id = ra.attribute_id
		WHERE ra.resource_id = ?;
	`, resourceID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	var attributes []Attribute

	for rows.Next() {
		var attribute Attribute
		err := rows.Scan(&attribute.Key, &attribute.Value)
		if err != nil {
			return nil, err
		}

		attributes = append(attributes, attribute)
	}

	return attributes, nil
}

func newID() string {
	uuid, err := uuid.NewV7()
	if err != nil {
		panic(err)
	}

	return uuid.String()
}

func (s *SQLiteStore) CreatePolicy(effect, action, conditionAttributeKey, conditionAttributeValue string) error {
	_, err := s.db.Exec(`
		INSERT INTO policies (id, effect, action, condition_attribute_key, condition_attribute_value)
		VALUES (?, ?, ?, ?, ?);
	`, newID(), effect, action, conditionAttributeKey, conditionAttributeValue)
	return err
}

func (s *SQLiteStore) createTables(db *sql.DB) error {
	_, err := db.Exec(`
		CREATE TABLE IF NOT EXISTS users (
			id TEXT PRIMARY KEY,
			username TEXT NOT NULL
		);

		CREATE TABLE IF NOT EXISTS resources (
			id TEXT PRIMARY KEY,
			name TEXT NOT NULL
		);

		CREATE TABLE IF NOT EXISTS attributes (
			id TEXT PRIMARY KEY,
			key TEXT NOT NULL,
			value TEXT NOT NULL
		);

		CREATE TABLE IF NOT EXISTS user_attributes (
			user_id TEXT NOT NULL,
			attribute_id INTEGER NOT NULL,
			FOREIGN KEY (user_id) REFERENCES users(id),
			FOREIGN KEY (attribute_id) REFERENCES attributes(id)
		);

		CREATE TABLE IF NOT EXISTS resource_attributes (
			resource_id TEXT NOT NULL,
			attribute_id TEXT NOT NULL,
			FOREIGN KEY (resource_id) REFERENCES resources(id),
			FOREIGN KEY (attribute_id) REFERENCES attributes(id)
		);

		CREATE TABLE IF NOT EXISTS policies (
			id TEXT PRIMARY KEY,
			effect TEXT NOT NULL CHECK(effect IN ('Allow', 'Deny')),
			action TEXT NOT NULL,
			condition_attribute_key TEXT,
			condition_attribute_value TEXT
		);
	`)
	return err
}