oc-tryton-rpc-typescript/cache.ts

/**
 * Cache system similar to Python's CacheDict from Tryton
 * Implements LRU (Least Recently Used) cache using JavaScript Map
 * TypeScript version
 */

export type CacheFactory<T> = () => T;

export class CacheDict<K = any, V = any> extends Map<K, V> {
    private cacheLen: number;
    private defaultFactory: CacheFactory<V> | null;

    /**
     * Create a new CacheDict
     */
    constructor(
        cacheLen: number = 10,
        defaultFactory: CacheFactory<V> | null = null
    ) {
        super();
        this.cacheLen = cacheLen;
        this.defaultFactory = defaultFactory;
    }

    /**
     * Set a key-value pair and maintain LRU order
     */
    override set(key: K, value: V): this {
        // If key exists, delete it first to move to end
        if (this.has(key)) {
            this.delete(key);
        }

        super.set(key, value);

        // Remove oldest entries if cache is full
        while (this.size > this.cacheLen) {
            const firstKey = this.keys().next().value;
            if (firstKey !== undefined) {
                this.delete(firstKey);
            }
        }

        return this;
    }

    /**
     * Get a value and move it to end (most recently used)
     */
    override get(key: K): V | undefined {
        if (this.has(key)) {
            const value = super.get(key)!;
            // Move to end by re-setting
            this.delete(key);
            super.set(key, value);
            return value;
        }

        // Handle missing key with default factory
        if (this.defaultFactory) {
            const value = this.defaultFactory();
            this.set(key, value);
            return value;
        }

        return undefined;
    }

    /**
     * Override has() to update LRU order on access
     */
    override has(key: K): boolean {
        const exists = super.has(key);
        if (exists) {
            // Move to end on access
            const value = super.get(key)!;
            this.delete(key);
            super.set(key, value);
        }
        return exists;
    }

    /**
     * Get current cache size
     */
    get length(): number {
        return this.size;
    }

    /**
     * Clear all items from cache
     */
    override clear(): void {
        super.clear();
    }

    /**
     * Convert cache to array for debugging
     */
    toArray(): Array<[K, V]> {
        return Array.from(this.entries());
    }
}

export interface CacheEntry<T = any> {
    expire: Date;
    value: T;
}

export interface CacheStats {
    totalPrefixes: number;
    totalEntries: number;
    prefixes: Record<string, number>;
}

/**
 * Advanced cache for Tryton RPC with expiration support
 */
export class TrytonCache {
    private store: CacheDict<string, CacheDict<string, CacheEntry>>;
    private cacheLen: number;

    constructor(cacheLen: number = 1024) {
        this.cacheLen = cacheLen;
        this.store = new CacheDict<string, CacheDict<string, CacheEntry>>(
            cacheLen,
            () => new CacheDict<string, CacheEntry>(cacheLen)
        );
    }

    /**
     * Check if a prefix is cached
     */
    cached(prefix: string): boolean {
        return this.store.has(prefix);
    }

    /**
     * Set cache entry with expiration
     */
    set(prefix: string, key: string, expire: number | Date, value: any): void {
        let expiration: Date;

        if (typeof expire === "number") {
            // Assume seconds, convert to Date
            expiration = new Date(Date.now() + expire * 1000);
        } else if (expire instanceof Date) {
            expiration = expire;
        } else {
            throw new Error("Invalid expiration type");
        }

        // Deep copy value to avoid mutations
        const cachedValue = this._deepCopy(value);

        this.store.get(prefix)!.set(key, {
            expire: expiration,
            value: cachedValue,
        });
    }

    /**
     * Get cached value if not expired
     */
    get(prefix: string, key: string): any {
        const now = new Date();

        if (!this.store.has(prefix)) {
            throw new Error("Key not found");
        }

        const prefixCache = this.store.get(prefix)!;
        if (!prefixCache.has(key)) {
            throw new Error("Key not found");
        }

        const entry = prefixCache.get(key)!;

        if (entry.expire < now) {
            prefixCache.delete(key);
            throw new Error("Key expired");
        }

        console.log(`(cached) ${prefix} ${key}`);
        return this._deepCopy(entry.value);
    }

    /**
     * Clear cache for a specific prefix or all
     */
    clear(prefix?: string): void {
        if (prefix) {
            if (this.store.has(prefix)) {
                this.store.get(prefix)!.clear();
            }
        } else {
            this.store.clear();
        }
    }

    /**
     * Deep copy objects to prevent mutations
     */
    private _deepCopy<T>(obj: T): T {
        if (obj === null || typeof obj !== "object") {
            return obj;
        }

        if (obj instanceof Date) {
            return new Date(obj.getTime()) as T;
        }

        if (obj instanceof Array) {
            return obj.map((item) => this._deepCopy(item)) as T;
        }

        // Handle Buffer in Node.js environment
        if (typeof Buffer !== "undefined" && obj instanceof Buffer) {
            return Buffer.from(obj) as T;
        }

        if (typeof obj === "object") {
            const copy: any = {};
            for (const key in obj) {
                if (Object.prototype.hasOwnProperty.call(obj, key)) {
                    copy[key] = this._deepCopy((obj as any)[key]);
                }
            }
            return copy as T;
        }

        return obj;
    }

    /**
     * Get cache statistics
     */
    getStats(): CacheStats {
        const stats: CacheStats = {
            totalPrefixes: this.store.size,
            totalEntries: 0,
            prefixes: {},
        };

        for (const [prefix, prefixCache] of this.store.entries()) {
            const count = prefixCache.size;
            stats.totalEntries += count;
            stats.prefixes[prefix] = count;
        }

        return stats;
    }

    /**
     * Remove expired entries
     */
    cleanupExpired(): number {
        const now = new Date();
        let removedCount = 0;

        for (const [prefix, prefixCache] of this.store.entries()) {
            const keysToRemove: string[] = [];

            for (const [key, entry] of prefixCache.entries()) {
                if (entry.expire < now) {
                    keysToRemove.push(key);
                }
            }

            keysToRemove.forEach((key) => {
                prefixCache.delete(key);
                removedCount++;
            });
        }

        return removedCount;
    }

    /**
     * Get cache size in bytes (approximate)
     */
    getSizeEstimate(): number {
        let size = 0;

        for (const [prefix, prefixCache] of this.store.entries()) {
            size += prefix.length * 2; // UTF-16 encoding

            for (const [key, entry] of prefixCache.entries()) {
                size += key.length * 2;
                size += JSON.stringify(entry.value).length * 2;
                size += 24; // Date object overhead
            }
        }

        return size;
    }
}