import { createReducerObject } from 'create-reducer-object';

import {
    DOC_CREATED,
    DOC_CREATE_RESPONDED,
    DOC_READ,
    DOC_READ_RESPONDED,
    DOC_UPDATED,
    DOC_UPDATE_RESPONDED,
    DOC_DELETED,
    DOC_DELETE_RESPONDED
} from 'constants/actions';

export const initialState = {};

function insertDoc(routeDocs, id, pending, fields) {
    return [
        ...routeDocs,
        {
            id,
            pending,
            ...fields
        }
    ];
}

function updateDoc(routeDocs, index, id, pending, fields = {}) {
    if (index === -1) {
        return insertDoc(routeDocs, id, false, fields);
    }

    return [
        ...routeDocs.slice(0, index - 1),
        {
            ...routeDocs[index],
            id,
            pending,
            ...fields
        },
        ...routeDocs.slice(index + 1)
    ];
}

function deleteDoc(docs, index) {
    return docs.slice(0, index - 1)
        .concat(docs.slice(index + 1));
}

function getRouteDocs(state, route) {
    if (state[route]) {
        return state[route].items;
    }

    return [];
}

function onCreate(state, { route, pendingId, fields }) {
    if (state[route] && state[route].loading) {
        return {};
    }

    const routeDocs = getRouteDocs(state, route);

    return {
        [route]: {
            loading: true,
            items: insertDoc(routeDocs, pendingId, true, fields)
        }
    };
}

function onCreateResponse(state, { route, pendingId, err, response }) {
    const routeDocs = getRouteDocs(state, route);

    const index = routeDocs.findIndex(({ id }) => id === pendingId);

    if (err) {
        const newRoute = {
            ...(state[route] || {}),
            error: true
        };

        if (index === -1) {
            return {
                [route]: newRoute
            };
        }

        return {
            [route]: {
                ...newRoute,
                items: deleteDoc(routeDocs, index)
            }
        };
    }

    const { id: actualId, ...fields } = response.data;

    return {
        [route]: {
            ...state[route],
            items: updateDoc(routeDocs, index, actualId, false, fields)
        }
    };
}

function onRead(state, { route }) {
    if (state[route]) {
        return {
            [route]: {
                ...state[route],
                loading: true
            }
        };
    }

    return {
        [route]: {
            loading: true,
            items: []
        }
    };
}

function onReadResponse(state, { route, err, response }) {
    if (err) {
        return {
            [route]: {
                ...(state[route] || {}),
                loading: false,
                error: true
            }
        };
    }

    return {
        [route]: {
            ...(state[route] || {}),
            loading: false,
            error: false,
            items: response.data[route]
        }
    };
}

function onUpdate(state, { route, id, fields }) {
    if (state[route] && state[route].loading) {
        return {};
    }

    const routeDocs = getRouteDocs(state, route);

    const index = routeDocs.findIndex(({ id: docId }) => docId === id);

    return {
        [route]: {
            loading: true,
            items: updateDoc(routeDocs, index, id, true, fields)
        }
    };

}

function onUpdateResponse(state, { route, id, err }) {
    const routeDocs = getRouteDocs(state, route);

    const index = routeDocs.findIndex(({ id: docId }) => docId === id);

    const newItems = updateDoc(routeDocs, index, id, false);

    if (err) {
        const newRoute = {
            ...(state[route] || {}),
            error: true
        };

        if (index === -1) {
            return {
                [route]: newRoute
            };
        }

        return {
            [route]: {
                ...newRoute,
                items: newItems
            }
        };
    }

    return {
        [route]: {
            ...state[route],
            error: false,
            items: newItems
        }
    };
}

function onDelete(state, { route, id }) {
    const routeDocs = getRouteDocs(state, route);

    const index = routeDocs.findIndex(({ id: docId }) => docId === id);

    return {
        [route]: {
            ...state[route],
            error: false,
            items: updateDoc(routeDocs, index, id, true)
        }
    };
}

function onDeleteResponse(state, { route, id, err }) {
    const routeDocs = getRouteDocs(state, route);

    const index = routeDocs.findIndex(({ id: docId }) => docId === id);

    if (err) {
        return {
            [route]: {
                ...state[route],
                error: true,
                items: updateDoc(routeDocs, index, id, false)
            }
        };
    }

    return {
        [route]: {
            ...state[route],
            error: false,
            items: deleteDoc(routeDocs, index)
        }
    };
}

const reducerMap = {
    [DOC_CREATED]: onCreate,
    [DOC_CREATE_RESPONDED]: onCreateResponse,
    [DOC_READ]: onRead,
    [DOC_READ_RESPONDED]: onReadResponse,
    [DOC_UPDATED]: onUpdate,
    [DOC_UPDATE_RESPONDED]: onUpdateResponse,
    [DOC_DELETED]: onDelete,
    [DOC_DELETE_RESPONDED]: onDeleteResponse
};

export const crud = createReducerObject(reducerMap, initialState);