import warning from '../libs/warning'
import { set } from '../shared/util'

export function isNullValue(value) {
    return value === null || value === undefined
}

/**
 * fix: setting data field "xxx" to undefined is invalid.
 *
 * @param {*} value 
 * @returns 
 */
export function fixNullValue(value) {
    return isNullValue(value) ? null : value
}

export function flattenArray(arr) {
    return Array.prototype.concat.apply([], arr)
}

export function treeTraverse(path = '', tree, isLeafNode, errorMessage, callback) {
    if (isLeafNode(path, tree)) {
        callback(path, tree)
    } else if (tree === undefined || tree === null) {
        // Do nothing
    } else if (Array.isArray(tree)) {
        tree.forEach((subTree, index) => treeTraverse(
            `${path}[${index}]`,
            subTree,
            isLeafNode,
            errorMessage,
            callback
        ))
    } else { // It's object and not a leaf node
        if (typeof tree !== 'object') {
            warning(false, errorMessage)
            return
        }
        Object.keys(tree).forEach(subTreeKey => {
            const subTree = tree[subTreeKey]
            treeTraverse(
                `${path}${path ? '.' : ''}${subTreeKey}`,
                subTree,
                isLeafNode,
                errorMessage,
                callback
            )
        })
    }
}

export function flattenFields(maybeNestedFields, isLeafNode, errorMessage) {
    const fields = {}
    treeTraverse(undefined, maybeNestedFields, isLeafNode, errorMessage, (path, node) => {
        fields[path] = node
    })
    return fields
}

export function normalizeValidateRules(validate, rules, validateTrigger) {
    const validateRules = validate.map((item) => {
        const newItem = {
            ...item,
            trigger: item.trigger || [],
        }
        if (typeof newItem.trigger === 'string') {
            newItem.trigger = [newItem.trigger]
        }
        return newItem
    })
    if (rules) {
        validateRules.push({
            trigger: validateTrigger ? [].concat(validateTrigger) : [],
            rules,
        })
    }
    return validateRules
}

export function getValidateTriggers(validateRules) {
    return validateRules
        .filter(item => !!item.rules && item.rules.length)
        .map(item => item.trigger)
        .reduce((pre, curr) => pre.concat(curr), [])
}

export function getParams(ns, opt, cb) {
    let names = ns
    let options = opt
    let callback = cb
    if (cb === undefined) {
        if (typeof names === 'function') {
            callback = names
            options = {}
            names = undefined
        } else if (Array.isArray(names)) {
            if (typeof options === 'function') {
                callback = options
                options = {}
            } else {
                options = options || {}
            }
        } else {
            callback = options
            options = names || {}
            names = undefined
        }
    }
    return {
        names,
        options,
        callback,
    }
}

export function isEmptyObject(obj) {
    return Object.keys(obj).length === 0
}

export function hasRules(validate) {
    if (validate) {
        return validate.some((item) => {
            return item.rules && item.rules.length
        })
    }
    return false
}

export function getErrorStrs(errors) {
    if (errors) {
        return errors.map((e) => {
            if (e && e.message) {
                return e.message
            }
            return e
        })
    }
    return errors
}

export function startsWith(str, prefix) {
    return str.lastIndexOf(prefix, 0) === 0
}

export function getValueFromEvent(e) {
    const getValue = (target) =>
        target.type === 'checkbox' ? target.checked : target.value
    // To support custom element
    if (!e || !e.detail) {
        if (!!e) {
            return getValue(e)
        }
        return e
    }
    return getValue(e.detail)
}

/**
 * ## 转换校验规则，使之支持 async-validator
 * 注意：由于小程序 data 不支持传入 RegExp & function，所以在设置 rules 需要传入字符串映射！！！
 * 
 * @example
 * ```
 * // 手机号验证
 * rules="{{ [{ required: true, pattern: '1[3456789]\d{9}' }] }}"
 * ```
 * @example
 * ```
 * // 自定义验证
 * rules="{{ [{ required: true, validator: 'checkMobile' }] }}"
 * 
 * Page({
 *   checkMobile(rule, value) {
 *     if (value) {
 *       return Promise.resolve()
 *     }
 *     return Promise.reject(new Error('手机号不能为空!'))
 *   }
 * })
 * ```
 * @example
 * ```
 * // 校验前去除空格
 * rules="{{ [{ required: true, transform: 'trim' }] }}"
 * 
 * Page({
 *   trim(value) {
 *     return value.trim()
 *   }
 * })
 * ```
 * @export
 * @param {array} rules 校验规则，设置字段的校验逻辑	
 * @param {object} vm 当前页面的实例对象
 * @return {array} 
 */
export function transformRules(rules, vm = getCurrentPages()[getCurrentPages().length - 1]) {
    return rules.map((rule) => {
        const cloneRule = { ...rule }
        // 正则表达式校验
        if (typeof rule.pattern === 'string') {
            cloneRule.pattern = new RegExp(rule.pattern)
        }
        // 校验前转换字段值
        if (typeof rule.transform === 'string' && vm && vm[rule.transform]) {
            cloneRule.transform = vm[rule.transform]
        }
        // 自定义校验，接收 Promise 作为返回值。
        if (typeof rule.validator === 'string' && vm && vm[rule.validator]) {
            cloneRule.validator = vm[rule.validator]
        }
        return cloneRule
    })
}

/**
 * ## Replace with template.
 * 
 * @example
 * ```
 * `I'm ${name}` + { name: 'bamboo' } = I'm bamboo
 * ```
 * @export
 * @param {*} template
 * @param {*} kv
 * @return {*} 
 */
export function replaceMessage(template, kv) {
    return template.replace(/\$\{\w+\}/g, (str) => {
        const key = str.slice(2, -1);
        return kv[key];
    });
}

class Field {
    constructor(fields) {
        Object.assign(this, fields);
    }
}

export function isFormField(obj) {
    return obj instanceof Field;
}

export function createFormField(field) {
    if (isFormField(field)) {
        return field;
    }
    return new Field(field);
}

export function internalFlattenFields(fields) {
    return flattenFields(
        fields,
        (_, node) => isFormField(node),
        'You must wrap field data with `createFormField`.'
    )
}

class FieldsStore {
    constructor(fields = {}) {
        this.fields = internalFlattenFields(fields)
        this.fieldsMeta = {}
    }

    updateFields(fields) {
        this.fields = internalFlattenFields(fields)
    }

    flattenRegisteredFields(fields) {
        const validFieldsName = this.getAllFieldsName();
        return flattenFields(
            fields,
            path => validFieldsName.indexOf(path) >= 0,
            'You cannot set a form field before rendering a field associated with the value.'
        )
    }

    setFieldsInitialValue = (initialValues) => {
        const flattenedInitialValues = this.flattenRegisteredFields(initialValues)
        const fieldsMeta = this.fieldsMeta
        Object.keys(flattenedInitialValues).forEach(name => {
            if (fieldsMeta[name]) {
                const fieldMeta = this.getFieldMeta(name)
                const initValue = fieldMeta.initialValue
                if (isNullValue(initValue)) {
                    this.setFieldMeta(name, {
                        ...fieldMeta,
                        initialValue: fixNullValue(flattenedInitialValues[name]),
                    });
                }
            }
        })
    }

    setFields(fields) {
        const nowFields = {
            ...this.fields,
            ...fields,
        }
        this.fields = nowFields
    }

    resetFields(ns) {
        const { fieldsMeta } = this
        const names = ns ?
            this.getValidFieldsFullName(ns) :
            this.getAllFieldsName()
        return names.reduce((acc, name) => {
            const fieldMeta = fieldsMeta[name]
            if (fieldMeta) {
                acc[name] = { value: fixNullValue(fieldMeta.initialValue) }
            }
            return acc
        }, {})
    }

    setFieldMeta(name, meta) {
        this.fieldsMeta[name] = meta
    }

    setFieldsAsDirty() {
        Object.keys(this.fields).forEach((name) => {
            const field = this.fields[name]
            const fieldMeta = this.fieldsMeta[name]
            if (field && fieldMeta && hasRules(fieldMeta.validate)) {
                this.fields[name] = {
                    ...field,
                    dirty: true,
                }
            }
        })
    }

    getFieldMeta(name) {
        this.fieldsMeta[name] = this.fieldsMeta[name] || {}
        return this.fieldsMeta[name]
    }

    getValueFromFields(name, fields) {
        const field = fields[name]
        if (field && 'value' in field) {
            return fixNullValue(field.value)
        }
        const fieldMeta = this.getFieldMeta(name)
        return fieldMeta && fixNullValue(fieldMeta.initialValue)
    }

    getAllValues = () => {
        const { fieldsMeta, fields } = this
        return Object.keys(fieldsMeta)
            .reduce((acc, name) => set(acc, name, this.getValueFromFields(name, fields)), {})
    }

    getValidFieldsName() {
        const { fieldsMeta } = this
        return fieldsMeta ?
            Object.keys(fieldsMeta).filter(name => !this.getFieldMeta(name).hidden) :
            []
    }

    getAllFieldsName() {
        const { fieldsMeta } = this
        return fieldsMeta ? Object.keys(fieldsMeta) : []
    }

    getValidFieldsFullName(maybePartialName) {
        const maybePartialNames = Array.isArray(maybePartialName) ?
            maybePartialName : [maybePartialName]
        return this.getValidFieldsName()
            .filter(fullName => maybePartialNames.some(partialName => (
                fullName === partialName || (
                    startsWith(fullName, partialName) &&
            ['.', '['].indexOf(fullName[partialName.length]) >= 0
                )
            )))
    }

    getFieldValuePropValue(fieldMeta) {
        const { name, valuePropName } = fieldMeta
        const field = this.getField(name)
        const fieldValue = 'value' in field ? field.value : fieldMeta.initialValue

        return {
            [valuePropName]: fixNullValue(fieldValue),
        }
    }

    getField(name) {
        return {
            ...this.fields[name],
            name,
        }
    }

    getNotCollectedFields() {
        const fieldsName = this.getValidFieldsName();
        return fieldsName
            .filter(name => !this.fields[name])
            .map(name => ({
                name,
                dirty: false,
                value: this.getFieldMeta(name).initialValue,
            }))
            .reduce((acc, field) => set(acc, field.name, createFormField(field)), {});
    }

    getNestedAllFields() {
        return Object.keys(this.fields)
            .reduce(
                (acc, name) => set(acc, name, createFormField(this.fields[name])),
                this.getNotCollectedFields()
            );
    }

    getFieldMember(name, member) {
        return this.getField(name)[member]
    }

    getNestedFields(names, getter) {
        const fields = names || this.getValidFieldsName()
        return fields.reduce((acc, f) => set(acc, f, getter(f)), {})
    }

    getNestedField(name, getter) {
        const fullNames = this.getValidFieldsFullName(name)
        if (
            fullNames.length === 0 || // Not registered
            (fullNames.length === 1 && fullNames[0] === name) // Name already is full name.
        ) {
            return getter(name)
        }
        const isArrayValue = fullNames[0][name.length] === '['
        const suffixNameStartIndex = isArrayValue ? name.length : name.length + 1
        return fullNames
            .reduce(
                (acc, fullName) => set(
                    acc,
                    fullName.slice(suffixNameStartIndex),
                    getter(fullName)
                ),
                isArrayValue ? [] : {}
            )
    }

    getFieldsValue = (names) => {
        return this.getNestedFields(names, this.getFieldValue)
    }

    getFieldValue = (name) => {
        const { fields } = this
        return this.getNestedField(name, (fullName) => this.getValueFromFields(fullName, fields))
    }

    getFieldsError = (names) => {
        return this.getNestedFields(names, this.getFieldError)
    }

    getFieldError = (name) => {
        return this.getNestedField(
            name,
            (fullName) => getErrorStrs(this.getFieldMember(fullName, 'errors'))
        )
    }

    isFieldValidating = (name) => {
        return this.getFieldMember(name, 'validating')
    }

    isFieldsValidating = (ns) => {
        const names = ns || this.getValidFieldsName()
        return names.some((n) => this.isFieldValidating(n))
    }

    isFieldTouched = (name) => {
        return this.getFieldMember(name, 'touched')
    }

    isFieldsTouched = (ns) => {
        const names = ns || this.getValidFieldsName()
        return names.some((n) => this.isFieldTouched(n))
    }

    clearField(name) {
        delete this.fields[name]
        delete this.fieldsMeta[name]
    }
}

export default function createFieldsStore(fields) {
    return new FieldsStore(fields)
}