import React, { Component, PropTypes } from 'react'
import isEqual from 'lodash/isEqual'
import get from 'lodash/get'
import cloneDeep from 'lodash/cloneDeep'
import set from 'lodash/set'

export default class Form extends Component {
  static propTypes = {
    initialValues: PropTypes.object,
    validations: PropTypes.object
  }

  static defaultProps = {
    initialValues: {}
  }

  constructor(props) {
    super(props)
    this.state = { values: props.initialValues }
  }

  isPristine = () => {
    return isEqual(this.state.values, this.props.initialValues)
  }

  getValue = path => {
    return get(this.state.values, path, '')
  }

  setValue = (path, value) => {
    this.setState({ values: set(cloneDeep(this.state.values), path, value) })
  }

  getErrors = () => {
    if (!this.props.validations) {
      return null
    }
    const errors = Object.keys(this.props.validations).reduce((result, path) => ({
      ...result,
      [path]: this.props.validations[path]
        .map(validation => validation(this.getValue(path), this.state.values))
        .find(error => error)
    }), {})
    return Object.keys(errors).find(path => errors[path]) ? errors : null
  }

  getError = path => {
    const errors = this.getErrors()
    return errors ? errors[path] : null
  }

  reset = () => {
    this.setState({ values: this.props.initialValues })
  }

  render() {
    const { initialValues, validations, ...other } = this.props
    return (
      <form {...other}>
        {this.props.children({
          ...this.state,
          isPristine: this.isPristine,
          getValue: this.getValue,
          setValue: this.setValue,
          getErrors: this.getErrors,
          getError: this.getError,
          reset: this.reset
        })}
      </form>
    )
  }
}