export default class KanbanAPI {
    static endpoint = "./api/tasks.php";

    static tasks = [];

    static async load() {
        const response = await KanbanAPI.request(
            KanbanAPI.endpoint
        );

        KanbanAPI.tasks = Array.isArray(response.tasks)
            ? response.tasks
            : [];

        return KanbanAPI.tasks;
    }

    static getItems(columnId) {
        const numericColumnId = Number(columnId);

        return KanbanAPI.tasks
            .filter(
                task =>
                    Number(task.columnId) === numericColumnId
            )
            .sort(
                (first, second) =>
                    Number(first.position) -
                    Number(second.position)
            );
    }

    static getItem(itemId) {
        const numericItemId = Number(itemId);

        return KanbanAPI.tasks.find(
            task => Number(task.id) === numericItemId
        ) ?? null;
    }

    static async insertItem(itemData) {
        const response = await KanbanAPI.request(
            KanbanAPI.endpoint,
            {
                method: "POST",
                body: JSON.stringify(itemData)
            }
        );

        KanbanAPI.tasks.push(response.task);

        return response.task;
    }

    static async updateItem(itemId, newProps) {
        const response = await KanbanAPI.request(
            KanbanAPI.endpoint,
            {
                method: "PUT",
                body: JSON.stringify({
                    id: Number(itemId),
                    ...newProps
                })
            }
        );

        const index = KanbanAPI.tasks.findIndex(
            task => Number(task.id) === Number(itemId)
        );

        if (index !== -1) {
            KanbanAPI.tasks[index] = response.task;
        } else {
            KanbanAPI.tasks.push(response.task);
        }

        /*
         * Reloading after a move guarantees that every task has
         * the correct position after SQLite reorders the column.
         */
        if (
            newProps.columnId !== undefined ||
            newProps.position !== undefined
        ) {
            await KanbanAPI.load();
        }

        return response.task;
    }

    static async deleteItem(itemId) {
        const response = await KanbanAPI.request(
            KanbanAPI.endpoint,
            {
                method: "DELETE",
                body: JSON.stringify({
                    id: Number(itemId)
                })
            }
        );

        KanbanAPI.tasks = KanbanAPI.tasks.filter(
            task => Number(task.id) !== Number(itemId)
        );

        return response.success === true;
    }

    static async request(url, options = {}) {
        const response = await fetch(url, {
            ...options,
            headers: {
                "Accept": "application/json",
                "Content-Type": "application/json",
                ...(options.headers ?? {})
            }
        });

        let data;

        try {
            data = await response.json();
        } catch {
            throw new Error(
                `The server returned an invalid response (${response.status}).`
            );
        }

        if (!response.ok) {
            throw new Error(
                data.error ??
                `Request failed with status ${response.status}.`
            );
        }

        return data;
    }
}