import React from 'react';
import { Alert } from 'react-bootstrap';
import { WaitIcon, Errors } from '../../components';
import { getValue, formatString, isString } from '../../commons/utils';
import { arrangeGrid } from '../../commons/grid-utils';

/**
 * Create the form content for the given form component
 * @param  {Form} form The form component
 * @return {React.Component} The rendered form content
 */
export default function formRender(form) {
    const resources = form.state.resources || form.props.resources;
    if (!resources) {
        return React.createElement(WaitIcon, { type: 'card' });
    }

    let errors = form.props.errors;

    const handledErrors = [];

    // check if there is any global error message
    let globalMsg = errors instanceof Error ? errors.message : null;

    // is not a list of error messages ?
    if (errors instanceof Error) {
        errors = null;
    }

    const snapshots = form.state.snapshots;

    // create the list of components and its size
    const items = snapshots.map(item => {
        const snapshot = item.snapshot;
        const compErrors = snapshot.property ? propertyErrors(snapshot.property, errors, handledErrors) : null;

        // get the value
        let value;
        if (snapshot.value) {
            value = snapshot.value;
            if (isString(value)) {
                value = formatString(value, form.props.doc);
            }
        } else {
            value = snapshot.property ? getValue(form.props.doc, snapshot.property) : null;
        }

        const comp = createElement(form, item, value, compErrors, resources);

        const size = snapshot.size ? snapshot.size : { sm: 12 };
        return { size: size, content: comp, newRow: snapshot.newRow, spanRow: snapshot.spanRow };
    });

    const lst = React.createElement(
        'div',
        { className: form.props.readOnly ? 'form-readonly' : 'form-edit' },
        arrangeGrid(items)
    );

    // called after the elements loop to search for unhandled messages
    if (!globalMsg) {
        globalMsg = createGlobalMsgs(errors, handledErrors);
    }

    // is there a global message
    if (globalMsg) {
        return React.createElement(
            'div',
            null,
            React.createElement(
                Alert,
                { bsStyle: 'danger' },
                globalMsg
            ),
            lst
        );
    }

    return lst;
}

/**
 * Create the component of a given schema
 * @param  {[type]} schema [description]
 * @param  {[type]} value  [description]
 * @param  {[type]} errors [description]
 * @return {[type]}        [description]
 */
function createElement(form, item, value, errors, resources) {
    const snapshot = item.snapshot;
    // get any resource that came from the object
    const res = resources[snapshot.id];

    // simplify error handling, sending just a string if there is
    // just one single error for the property
    let err;
    if (errors && errors.length === 1 && snapshot && errors[0].field === snapshot.property) {
        err = errors[0].msg;
    } else {
        err = errors;
    }

    const Comp = item.comp;

    if (__DEV__) {
        if (!Comp) {
            throw new Error('Invalid type: ' + snapshot.type);
        }
    }

    return React.createElement(Comp, { ref: snapshot.id,
        schema: snapshot,
        value: value,
        resources: res,
        onChange: form._onChange,
        errors: err,
        onRequest: form._onRequest });
}

/**
 * Return a list of errors of a specific field
 * @param  {[type]} propname [description]
 * @param  {[type]} errors   [description]
 * @return {[type]}          [description]
 */
function propertyErrors(propname, errors, handledErrors) {
    if (!errors) {
        return null;
    }

    const res = errors.filter(msg => {
        if (msg.field && msg.field === propname) {
            handledErrors.push(msg.field);
            return true;
        }
        return false;
    });

    return res.length === 0 ? null : res;
}

/**
 * Create a list of global messages based on unhandled messages by the fields
 * @return {[type]} [description]
 */
function createGlobalMsgs(errors, handledErrors) {
    if (!errors) {
        return null;
    }

    const lst = errors.filter(msg => handledErrors.indexOf(msg.field) === -1);

    return lst.length > 0 ? React.createElement(Errors, { messages: lst }) : null;
}