import { mapProp, Update } from "@/hooks/useStore";
import { getMediaTypeForFile } from "common/MediaType";

export function FileReducer(prev: FileReducer.State, action: FileReducer.Action): FileReducer.State {
	switch (action.type) {
		case "reset":
			return FileReducer.initial;
		case "file":
			if (prev.file !== null) {
				if (action.file !== null) {
					if (prev.file.name === prev.filename && getMediaTypeForFile(prev.file) === prev.mediaType) {
						return Object.freeze<FileReducer.State>({
							filename: action.file.name,
							mediaType: getMediaTypeForFile(action.file),
							file: action.file,
						});
					} else {
						return mapProp("file", action.file as File | null)(prev);
					}
				} else {
					if (prev.file.name === prev.filename && prev.file.type === prev.mediaType) {
						return FileReducer.initial;
					} else {
						return mapProp("file", action.file as File | null)(prev);
					}
				}
			} else {
				if (action.file !== null) {
					if (prev.filename === "" && prev.mediaType === "") {
						return Object.freeze<FileReducer.State>({
							filename: action.file.name,
							mediaType: getMediaTypeForFile(action.file),
							file: action.file,
						});
					} else {
						return mapProp("file", action.file as File | null)(prev);
					}
				} else {
					return prev;
				}
			}
		case "filename":
			return mapProp("filename", action.filename)(prev);
		case "mediaType":
			return mapProp("mediaType", action.mediaType)(prev);
	}
}

export namespace FileReducer {

	export interface ResetAction {
		readonly type: "reset";
	}

	export const reset: ResetAction = Object.freeze<ResetAction>({
		type: "reset",
	});

	export interface SetFileAction {
		readonly type: "file";
		readonly file: File | null;
	}

	export function setFile(file: File | null): SetFileAction {
		return Object.freeze<SetFileAction>({
			type: "file",
			file,
		});
	}

	export interface SetFilenameAction {
		readonly type: "filename";
		readonly filename: Update<string>;
	}

	export function setFilename(filename: Update<string>): SetFilenameAction {
		return Object.freeze<SetFilenameAction>({
			type: "filename",
			filename,
		});
	}

	export interface SetMediaTypeAction {
		readonly type: "mediaType";
		readonly mediaType: Update<string>;
	}

	export function setMediaType(mediaType: Update<string>): SetMediaTypeAction {
		return Object.freeze<SetMediaTypeAction>({
			type: "mediaType",
			mediaType,
		});
	}

	export type Action = ResetAction |
		SetFileAction |
		SetFilenameAction |
		SetMediaTypeAction;

	export interface State {
		readonly filename: string;
		readonly mediaType: string;
		readonly file: File | null;
	}

	export const initial: State = Object.freeze<State>({
		filename: "",
		mediaType: "",
		file: null,
	});
}