/**
 * Collection utilities - ES Module Version
 */

import { typeOf, isObject, isArray, isString, isFunction } from './Type.js';

/**
 * Iterate over collections
 */
export function forEach(collection, iterator, that) {
    const type = typeOf(collection);
    let i, key;
    
    if (type === 'object') {
        for (key in collection) {
            if (collection.hasOwnProperty(key)) {
                if (iterator.call(that, collection[key], key, collection) === false) {
                    break;
                }
            }
        }
    } else if (type === 'array' || type === 'string') {
        for (i = 0; i < collection.length; i++) {
            if (iterator.call(that, collection[i], i, collection) === false) {
                break;
            }
        }
    }
    
    return collection;
}

/**
 * Get length of collection
 */
export function len(collection) {
    const type = typeOf(collection);
    
    if (type === 'array' || type === 'string') {
        return collection.length;
    }
    
    if (type === 'object') {
        return Object.keys(collection).length;
    }
    
    return 0;
}

/**
 * Extend objects (similar to Object.assign but deeper)
 */
export function extend(...args) {
    let target = args[0] || {};
    let deep = false;
    let i = 1;
    
    // Check if deep copy
    if (typeof target === 'boolean') {
        deep = target;
        target = args[1] || {};
        i = 2;
    }
    
    for (; i < args.length; i++) {
        const source = args[i];
        if (!source) continue;
        
        for (const key in source) {
            if (source.hasOwnProperty(key)) {
                const src = target[key];
                const copy = source[key];
                
                // Prevent infinite loop
                if (target === copy) continue;
                
                if (deep && copy && (isObject(copy) || isArray(copy))) {
                    let clone;
                    if (isArray(copy)) {
                        clone = src && isArray(src) ? src : [];
                    } else {
                        clone = src && isObject(src) ? src : {};
                    }
                    target[key] = extend(deep, clone, copy);
                } else if (copy !== undefined) {
                    target[key] = copy;
                }
            }
        }
    }
    
    return target;
}

/**
 * Map over collections
 */
export function map(collection, iterator, that) {
    const type = typeOf(collection);
    const result = [];
    
    forEach(collection, function(value, key) {
        result.push(iterator.call(that, value, key, collection));
    });
    
    return type === 'string' ? result.join('') : result;
}

/**
 * Filter collections
 */
export function filter(collection, iterator, that) {
    const type = typeOf(collection);
    const result = type === 'object' ? {} : [];
    
    forEach(collection, function(value, key) {
        if (iterator.call(that, value, key, collection)) {
            if (type === 'object') {
                result[key] = value;
            } else {
                result.push(value);
            }
        }
    });
    
    return type === 'string' ? result.join('') : result;
}

/**
 * Find in collection
 */
export function find(collection, iterator, that) {
    let result;
    
    forEach(collection, function(value, key) {
        if (iterator.call(that, value, key, collection)) {
            result = value;
            return false; // break
        }
    });
    
    return result;
}

/**
 * Check if every element passes test
 */
export function every(collection, iterator, that) {
    let result = true;
    
    forEach(collection, function(value, key) {
        if (!iterator.call(that, value, key, collection)) {
            result = false;
            return false; // break
        }
    });
    
    return result;
}

/**
 * Check if any element passes test
 */
export function some(collection, iterator, that) {
    let result = false;
    
    forEach(collection, function(value, key) {
        if (iterator.call(that, value, key, collection)) {
            result = true;
            return false; // break
        }
    });
    
    return result;
}

/**
 * Get keys of object or indices of array
 */
export function keys(collection) {
    if (isObject(collection)) {
        return Object.keys(collection);
    }
    
    if (isArray(collection) || isString(collection)) {
        return Array.from({ length: collection.length }, (_, i) => i);
    }
    
    return [];
}

/**
 * Get values of collection
 */
export function values(collection) {
    if (isObject(collection)) {
        return Object.values(collection);
    }
    
    if (isArray(collection)) {
        return [...collection];
    }
    
    if (isString(collection)) {
        return collection.split('');
    }
    
    return [];
}

// Export all functions
export default {
    forEach,
    len,
    extend,
    map,
    filter,
    find,
    every,
    some,
    keys,
    values
};