import { project } from "./project.js";
import { submission } from "./submission.js";
import { element } from "./element.js";
import { exists, is_string } from "./functions.js";

class loader {
    #load_from;
    #database;
    #content;

    constructor(database, project) {
        if (typeof(database) !== "string") {
            throw "Database URL must be string.";
        }

        if (typeof(project) !== "string") {
            throw "Project file must be string.";
        }

        this.#database = database;
        this.#load_from = database + "/" + project;
        this.#content = null;
    }

    async load() {
        const fetched = await fetch(this.#load_from);
        
        if (fetched.status !== 200) {
            throw "Can not load database from " + this.#load_from;
        }

        try {
            const result = await fetched.json();
            this.#content = result;
        } catch (error) {
            throw "Database JSON is bad formated.";
        }
    }
    
    #prepare_image(url) {
        return this.#database + "/" + url;
    }

    #prepare_element(input) {
        if (!exists(input.name)) {
            return null;
        }

        const result = new element(input.name);

        if (exists(input.description)) {
            result.description = input.description;
        }

        if (exists(input.mesh)) {
            result.mesh = this.#prepare_image(input.mesh);
        }

        if (exists(input.thumbnail)) {
            result.thumbnail = this.#prepare_image(input.thumbnail);
        }
        
        if (exists(input.pictures)) {
            const pictures = Array.from(input.pictures);
        
            pictures.forEach(picture => {
                if (!is_string(picture)) {
                    return;
                }

                result.pictures.add(this.#prepare_image(picture));                
            });
        }

        if (exists(input.params)) {
            const names = Object.keys(input.params);
            
            names.forEach(name => {
                if (!is_string(name) || !is_string(input.params[name])) {
                    return;
                }

                result.params.set(name, input.params[name]);
            });
        }

        if (exists(input.shop)) {
            result.shop = input.shop;
        }

        return result;
    }

    #prepare_one(input) {
        if (typeof(input.name) === "undefined") {
            return null;
        }

        const result = new submission(input.name)
        
        if (typeof(input.description) !== "undefined") {
            result.description = input.description;
        }

        if (typeof(input.thumbnail) !== "undefined") {
            result.thumbnail = this.#prepare_image(input.thumbnail);
        }

        if (typeof(input.elements) === "undefined") {
            return result;
        }

        const elements = Array.from(input.elements);

        elements.forEach(data => {
            const current = this.#prepare_element(data);

            if (current !== null) {
                result.add(current);
            }
        });

        return result;
    }

    get loaded() {
        if (this.#content === null) {
            throw "Must load database before trying to access it.";
        }
        
        const content = this.#content;
        
        if (!exists(content.name)) {
            content.name = "Unnamed";
        }
        
        const result = new project(content.name);

        if (exists(content.description)) {
            result.description = content.description;
        }

        if (!exists(content.submissions)) {
            return result;
        }

        const submissions = Array.from(content.submissions);

        submissions.forEach(submission => {
            const item = this.#prepare_one(submission);

            if (item === null) {
                return;
            }

            result.add(item);
        });

        return result;
    }
}

export { loader };