import fs from 'fs/promises';
import { EventEmitter } from 'events';
import { v4 as uuidv4 } from 'uuid';

class GreenBean extends EventEmitter {
    constructor(dbPath = 'data.json') {
        super();
        this.dbPath = dbPath;
        this.data = null;
        this.initialized = false;
        this.frozen = false;
    }

    // Базовые операции с бинами
    async R(type, id = null) {
        if (!this.initialized) await this.init();

        if (id === null) {
            return this.dispense(type);
        }
        return this.load(type, id);
    }

    async dispense(type) {
        if (!this.initialized) await this.init();

        const bean = {
            id: uuidv4(),
            __type: type,
            __meta: {
                created: new Date().toISOString(),
                modified: new Date().toISOString()
            }
        };

        return new Proxy(bean, this.createHandler(type));
    }

    async load(type, id) {
        if (!this.initialized) await this.init();

        const item = this.data[type]?.find(item => item.id === id);
        if (!item) return null;

        return new Proxy({...item}, this.createHandler(type));
    }

    async store(bean) {
        if (this.frozen) throw new Error('Cannot modify frozen beans');
        if (!this.initialized) await this.init();

        const type = bean.__type;
        if (!this.data[type]) this.data[type] = [];

        bean.__meta.modified = new Date().toISOString();

        const index = this.data[type].findIndex(item => item.id === bean.id);
        if (index !== -1) {
            this.data[type][index] = {...bean};
        } else {
            this.data[type].push({...bean});
        }

        await this.save();
        return bean.id;
    }

    async trash(bean) {
        if (this.frozen) throw new Error('Cannot modify frozen beans');
        if (!this.initialized) await this.init();

        const type = bean.__type;
        if (!this.data[type]) return;

        this.data[type] = this.data[type].filter(item => item.id !== bean.id);
        await this.save();
    }

    // Работа со связями
    async own(bean, property, related) {
        if (!Array.isArray(related)) related = [related];

        bean[property] = related.map(item => ({
            id: item.id,
            __type: item.__type
        }));

        await this.store(bean);
    }

    async link(bean, linkType, attributes = {}) {
        const link = await this.dispense(linkType);
        Object.assign(link, attributes, {
            [`${bean.__type}Id`]: bean.id
        });
        await this.store(link);
        return link;
    }

    async find(type, criteria = {}) {
        if (!this.initialized) await this.init();

        if (!this.data[type]) return [];

        return this.data[type]
            .filter(item => {
                return Object.entries(criteria).every(([key, value]) =>
                    item[key] === value
                );
            })
            .map(item => new Proxy({...item}, this.createHandler(type)));
    }

    async findOne(type, criteria = {}) {
        const results = await this.find(type, criteria);
        return results[0] || null;
    }

    // Вспомогательные методы
    async init() {
        try {
            const exists = await fs.access(this.dbPath)
                .then(() => true)
                .catch(() => false);

            if (exists) {
                const content = await fs.readFile(this.dbPath, 'utf-8');
                this.data = JSON.parse(content);
            } else {
                this.data = {};
            }

            this.initialized = true;
        } catch (error) {
            throw new Error(`Failed to initialize database: ${error.message}`);
        }
    }

    async save() {
        try {
            const tempPath = `${this.dbPath}.tmp`;
            await fs.writeFile(tempPath, JSON.stringify(this.data, null, 2));
            await fs.rename(tempPath, this.dbPath);
            this.emit('save');
        } catch (error) {
            throw new Error(`Failed to save database: ${error.message}`);
        }
    }

    createHandler(type) {
        return {
            get: (target, prop) => {
                if (prop.endsWith('List') && !target[prop]) {
                    target[prop] = [];
                }
                return target[prop];
            },
            set: (target, prop, value) => {
                if (this.frozen) throw new Error('Cannot modify frozen beans');

                if (prop.endsWith('List') && Array.isArray(value)) {
                    target[prop] = value.map(item => ({
                        id: item.id,
                        __type: item.__type || type
                    }));
                } else {
                    target[prop] = value;
                }
                return true;
            }
        };
    }

    // Утилиты
    freeze(frozen = true) {
        this.frozen = frozen;
    }

    async nuke() {
        if (this.frozen) throw new Error('Cannot nuke frozen database');
        this.data = {};
        await this.save();
    }

    async transaction(callback) {
        const snapshot = JSON.stringify(this.data);
        try {
            const result = await callback();
            await this.save();
            return result;
        } catch (error) {
            this.data = JSON.parse(snapshot);
            throw error;
        }
    }
}

export default GreenBean;