import FormUtils from '../form-utils';

/**
 * Create an snapshot of the form, based on the form schema and the document assigned to it.
 * An snapshot is the current status of the schema properties for the document. It is called
 * on the initialization of the form and whenever the document is changed during its editing,
 * so the new snapshot is compared with the previous one to update the fields in the form
 *
 * @param  {Object} schemas The form schema
 * @param  {Object} doc    The document in use
 * @param  {Object} parentSnapshot The parent snapshot in a component tree structure. Initially it is the own form
 * @return {Array}         List of form elements state to the given document
 */

export default function createSnaphost(form) {
    const creator = new SnapshotCreator(form);
    return creator.create(form);
}

/**
 * Responsible for creating a snapshot of a form
 */
class SnapshotCreator {

    /**
     * Create the snapshot of a given for
     * @param  {[type]} form [description]
     * @return {[type]}      [description]
     */
    create(form) {
        this.form = form;
        const schema = form.props.schema;
        const formSnapshot = form.props.readOnly ? { readOnly: form.props.readOnly } : {};

        this.form = form;
        this.list = [];

        this._traverse(schema.controls, formSnapshot);

        return this.list;
    }

    _traverse(schemas, parent, pref) {
        const doc = this.form.props.doc;
        const self = this;

        schemas.forEach((schema, index) => {
            const comp = FormUtils.getControl(schema);
            // create new snapshot, using the parent to overwrite common properties
            const snapshot = Object.assign({}, comp.snapshot(schema, doc));

            // check for parent properties that must be followed by the children
            if (parent) {
                if (parent.visible === false) {
                    snapshot.visible = false;
                }

                if (parent.readOnly === true) {
                    snapshot.readOnly = true;
                }
            }

            // if not visible, don't include in the list
            if (!snapshot.visible) {
                return;
            }

            // the id of the element, composed with the parent name
            if (!snapshot.id) {
                snapshot.id = (pref ? pref + ':' : '') + (schema.property ? schema.property + index : 'ctrl' + index);
            }

            // list of children elements
            const children = comp.children(schema);

            // there is any children ?
            if (children) {
                self._traverse(children, snapshot, snapshot.id);
            } else {
                const data = {
                    // pointer to the original schema
                    schema: schema,
                    comp: comp,
                    snapshot: snapshot
                };
                self.list.push(data);
            }
        });
    }

}