export abstract class Collection<T> { constructor(name: string) { this.name = name; } private name!: string; private collection: T[] = [];
public async write() { const d = JSON.stringify(this.collection); const file = `${this.name}.json`; await Deno.writeTextFile(file, d); }
create(item: T): Promise<boolean> { const before = this.collection.length; const after = this.collection.push(item); return Promise.resolve(before < after); }
update(condition: any, item: T): Promise<T> { const [data] = this.collection .map((v, i) => { return { v, i }; }) .filter((data) => this.compare(condition, data.v)); this.collection[data.i] = item; return Promise.resolve(this.collection[data.i]); }
delete(condition: any): Promise<T[]> { const data = this.collection .map((v, i) => { return { v, i }; }) .filter((data) => { return this.compare(condition, data.v); }); data.forEach((item) => { this.collection.splice(item.i, 1); }); return Promise.resolve(this.collection); }
findOne(condition: any): Promise<T> { const item = this.collection.filter((v) => { return this.compare(condition, v); }); const [r] = item; return Promise.resolve(r); }
find(condition?: any): Promise<T[]> { const item = this.collection.filter((v) => { return this.compare(condition, v); }); return Promise.resolve(item); }
private comparable(value: any) { const compare = [ "$lt", "$lte", "$gt", "$gte", "$in", "$nin", "$ne", "$exists", "$regex", ]; const [key] = Object.keys(value); return compare.includes(key); }
private queryHandler(result: boolean, target?: string, regex?: RegExp) { if (target && regex) return result && regex.test(target); return result; }
private nextCompare(comparator: any, target: any) { const [operator, regex] = Object.keys(comparator); const value = comparator[operator]; const regexValue = comparator[regex]; if (operator === "$gt") { return this.queryHandler(target > value, target, regexValue); } if (operator === "$gte") { return this.queryHandler(target >= value, target, regexValue); } if (operator === "$lt") { return this.queryHandler(target < value, target, regexValue); } if (operator === "$lte") { return this.queryHandler(target <= value, target, regexValue); } if (operator === "$ne") { return this.queryHandler(target !== value, target, regexValue); } if (operator === "$exists") { return this.queryHandler(target && value, target, regexValue); } if (operator === "$in") { const valueArray = value as any[]; const result = valueArray.includes(target); return this.queryHandler(result, target, regexValue); } if (operator === "$nin") { const valueArray = value as any[]; const result = !valueArray.includes(target); return this.queryHandler(result, target, regexValue); }
if (operator === "$regex") { const regex = new RegExp(value); regex.test(target); return this.queryHandler(regex.test(target)); } return false; }
private contain(target: any, condition: any) { const keys = Object.keys(condition); for (const key of keys) { const ckey = condition[key]; if (this.comparable(ckey)) return this.nextCompare(ckey, target[key]); if (ckey !== target[key]) { if ( typeof ckey == "object" && typeof target[key] == "object" ) { if (!this.contain(ckey, target[key])) return false; } else return false; } }
return true; }
private compare(condition: any, target: any) { return this.contain(target, condition); }}