/**
 * Formula.js
 *
 * @author realor
 */

import { ObjectUtils } from '../utils/ObjectUtils.js'

class Formula {
    /* Formula contructor: new Formula("position.x", "position.y + 1") */
    constructor(path, expression) {
        this.path = path
        this.expression = expression
        this.getFn = new Function('object', 'return object.' + path)
        this.setFn = ObjectUtils.createEvalFunction('object.' + path + '=' + expression)
    }

    evaluate(object) {
        return this.setFn(object)
    }

    /* static methods */

    static create(object, path, expression, evaluate = true) {
        if (object.formulas === undefined) {
            object.formulas = {}
        }
        const formula = new Formula(path, expression)
        if (evaluate) formula.evaluate(object)

        object.formulas[path] = formula
        return formula
    }

    static set(object, formula, evaluate = true) {
        if (object.formulas === undefined) {
            object.formulas = {}
        }
        if (evaluate) formula.evaluate(object)

        object.formulas[formula.path] = formula
        return formula
    }

    static get(object, path) {
        if (object.formulas) {
            return object.formulas[path]
        }
    }

    static getAll(object) {
        return object.formulas
    }

    static remove(object, path) {
        if (object.formulas) {
            if (path) {
                delete object.formulas[path]
            } else {
                object.formulas = {}
            }
        }
    }

    static isDefined(object, path = '') {
        if (object.formulas) {
            for (let key in object.formulas) {
                if (key.startsWith(path)) {
                    return true
                }
            }
        }
        return false
    }

    static eval(object, path) {
        if (object.formulas) {
            const formula = object.formulas[path]
            if (formula) {
                return formula.evaluate(object)
            }
        }
    }

    static update(object, path = '', prefix = path === '' ? true : false) {
        let updated = false

        if (object.formulas) {
            if (prefix) {
                const formulas = object.formulas
                for (let key in formulas) {
                    if (key.startsWith(path)) {
                        let formula = formulas[key]
                        const oldValue = formula.getFn(object)
                        const newValue = formula.setFn(object)
                        updated = updated || oldValue !== newValue
                    }
                }
            } else {
                const formula = object.formulas[path]
                if (formula) {
                    const oldValue = formula.getFn(object)
                    const newValue = formula.setFn(object)
                    updated = oldValue !== newValue
                }
            }
        }
        return updated
    }

    static updateTree(object, path = '', prefix = path === '' ? true : false) {
        const updatedObjects = []

        const updateFormulas = object => {
            if (Formula.update(object, path, prefix)) {
                updatedObjects.push(object)
            }

            for (let child of object.children) {
                updateFormulas(child)
            }
        }

        updateFormulas(object)

        return updatedObjects
    }

    static copy(target, source) {
        if (target.formulas === undefined) {
            target.formulas = {}
        }

        const targetFormulas = target.formulas
        const sourceFormulas = source.formulas
        for (let path in sourceFormulas) {
            targetFormulas[path] = sourceFormulas[path]
        }
    }
}

export { Formula }