import { Injectable } from '../../../di/src/decorator/Injection.ts'
import { getCookies, setCookie, deleteCookie, ServerRequest } from '../external/http.ts'
import { InMemCache } from '../support/InMemCache.ts'
import { HTTPRequest } from './type/HTTPRequest.ts'

/**
 * Base type representing a parsed cookie.
 */
export interface Cookie {
    key: string,
    original_value: string,
    value: any,
}

/**
 * Type representing what might be a cookie, or might be undefined.
 */
export type MaybeCookie = Cookie | undefined

// TODO cookie options (http only, expires, &c.)
/**
 * Base class for managing cookies.
 */
@Injectable()
export class CookieJar {
    /**
     * Cache of parsed cookie values.
     * @type object
     */
    protected _parsed: { [key: string]: string } = {}

    /**
     * Cache of cookie values.
     * @type InMemCache
     */
    protected _cache = new InMemCache()

    constructor(
        /**
         * The associated request.
         * @type HTTPRequest
         */
        protected request: HTTPRequest,
    ) {
        this._parsed = getCookies(this.request.to_native)
    }

    /**
     * Get the raw value of a cookie string, if it is defined.
     * @param {string} key
     * @return string | undefined
     */
    public async get_raw(key: string): Promise<string | undefined> {
        return this._parsed[key]
    }

    /**
     * Get the parsed value of a cookie, if it is defined.
     * @param {string} key
     * @return Promise<MaybeCookie>
     */
    public async get(key: string): Promise<MaybeCookie> {
        // Try the cache
        if ( await this._cache.has(key) ) {
            return JSON.parse((await this._cache.fetch(key)) || '""') as Cookie
        }

        // If the cache missed, try to parse it and load in cache
        if ( key in this._parsed ) {
            let value = this._parsed[key]
            try {
                value = JSON.parse(atob(this._parsed[key]))
            } catch(e) {}

            const cookie = {
                key,
                value,
                original_value: this._parsed[key],
            }

            await this._cache.put(key, JSON.stringify(cookie))
            return cookie
        }
    }

    /**
     * Set the cookie for the given key to the serialized value.
     * @param {string} key
     * @param value
     * @return Promise<void>
     */
    public async set(key: string, value: any): Promise<void> {
        const original_value = btoa(JSON.stringify(value))
        const cookie = {
            key,
            value,
            original_value,
        }

        await this._cache.put(key, JSON.stringify(cookie))
        setCookie(this.request.response, { name: key, value: original_value })
    }

    /**
     * Returns true if the given cookie exists.
     * @param {string} key
     * @return Promise<boolean>
     */
    public async has(key: string): Promise<boolean> {
        return (await this._cache.has(key)) || key in this._parsed
    }

    /**
     * Deletes the given cookie, if it exists.
     * @param {string} key
     * @return Promise<void>
     */
    public async delete(key: string): Promise<void> {
        await this._cache.drop(key)
        deleteCookie(this.request.response, key)
    }
}