interface SavedStory {
    id: string;
    // in *theory* we could fetch these from the cache, but if it's not there you'd have to wait years to open the homepage lol
    name: string;
    coverURL: string;
}

export default () => {
    // deno-lint-ignore ban-types
    const oldOnloadHandler: Function = window.onload ?? (() => {});

    window.onload = () => {
        oldOnloadHandler();
        // Sync to position button
        const position = localStorage.getItem(
            (new URL(document.URL)).searchParams.get(
                "id",
            ) as string + "_progress",
        );

        if (position) {
            const buttonsList = document.getElementById("detail-buttons");

            const buttonEle = document.createElement("button");
            buttonEle.className = "favorite-story-button";
            buttonEle.textContent = "Sync to story position";
            buttonEle.onclick = () => {
                const currURL = new URL(document.location.href);
                currURL.searchParams.set("chapter", position);
                window.location.href = currURL.toString();
            };
            buttonsList?.appendChild(buttonEle);
        }

        // Favorite button
        const button = document.getElementById("favorite");

        if (!button) throw "how did your button not init what";

        let savedStories: SavedStory[] = JSON.parse(
            localStorage.getItem("savedStories") ?? "[]",
        );

        function handler() {
            if (button?.textContent === "Favorite") {
                savedStories.push({
                    id: (new URL(document.URL)).searchParams.get(
                        "id",
                    ) as string,
                    name: document.getElementById("storyname")
                        ?.textContent as string,
                    coverURL: (document.getElementById(
                        "storycover",
                    ) as HTMLImageElement)
                        .src,
                });
                button.textContent = "Unfavorite";
            } else if (button?.textContent === "Unfavorite") {
                savedStories = savedStories.filter((story) =>
                    story.id !== (new URL(document.URL)).searchParams.get("id")
                );
                button.textContent = "Favorite";
            }
            localStorage.setItem("savedStories", JSON.stringify(savedStories));
        }

        if (
            savedStories.filter((story) =>
                story.id === (new URL(document.URL)).searchParams.get("id")
            ).length > 0
        ) {
            button.textContent = "Unfavorite";
        }

        button.onclick = handler;
    };
};