import { Service } from '../../../../di/src/decorator/Service.ts'
import { Logging } from '../logging/Logging.ts'
import {uuid} from '../../external/std.ts'

/**
 * Base service with some utility helpers.
 */
@Service()
export default class Utility {
    constructor(
        protected logger: Logging
    ) {}

    /**
     * Make a deep copy of an object.
     * @param target
     */
    deep_copy<T>(target: T): T {
        if ( target === null )
            return target

        if ( target instanceof Date )
            return new Date(target.getTime()) as any

        if ( target instanceof Array ) {
            const copy = [] as any[]
            (target as any[]).forEach(item => { copy.push(item) })
            return copy.map((item: any) => this.deep_copy<any>(item)) as any
        }

        if ( typeof target === 'object' && target !== {} ) {
            const copy = { ...(target as {[key: string]: any }) } as { [key: string]: any }
            Object.keys(copy).forEach(key => {
                copy[key] = this.deep_copy<any>(copy[key])
            })
        }

        return target
    }

    // TODO deep_merge

    /**
     * Given a string of a value, try to infer the JavaScript type.
     * @param {string} val
     */
    infer(val: string): any {
        if ( !val ) return undefined
        else if ( val.toLowerCase() === 'true' ) return true
        else if ( val.toLowerCase() === 'false' ) return false
        else if ( !isNaN(Number(val)) ) return Number(val)
        else if ( this.is_json(val) ) return JSON.parse(val)
        else if ( val.toLowerCase() === 'null' ) return null
        else if ( val.toLowerCase() === 'undefined' ) return undefined
        else return val
    }

    /**
     * Returns true if the given value is valid JSON.
     * @param {string} val
     */
    is_json(val: string): boolean {
        try {
            JSON.parse(val)
            return true
        } catch(e) {
            this.logger.verbose(`Error encountered while checking is_json. Might be invalid. Error: ${e.message}`)
            return false
        }
    }

    /**
     * Get a universally-unique ID string.
     * @return string
     */
    uuid(): string {
        return uuid()
    }
}