import type { EncounterStore } from "@initiative/application";
import {
	addCombatantUseCase,
	adjustHpUseCase,
	advanceTurnUseCase,
	editCombatantUseCase,
	removeCombatantUseCase,
	setHpUseCase,
	setInitiativeUseCase,
} from "@initiative/application";
import type { CombatantId, DomainEvent, Encounter } from "@initiative/domain";
import {
	combatantId,
	createEncounter,
	isDomainError,
} from "@initiative/domain";
import { useCallback, useEffect, useRef, useState } from "react";
import {
	loadEncounter,
	saveEncounter,
} from "../persistence/encounter-storage.js";

function createDemoEncounter(): Encounter {
	const result = createEncounter([
		{ id: combatantId("1"), name: "Aria" },
		{ id: combatantId("2"), name: "Brak" },
		{ id: combatantId("3"), name: "Cael" },
	]);

	if (isDomainError(result)) {
		throw new Error(`Failed to create demo encounter: ${result.message}`);
	}

	return result;
}

function initializeEncounter(): Encounter {
	const stored = loadEncounter();
	if (stored !== null) return stored;
	return createDemoEncounter();
}

function deriveNextId(encounter: Encounter): number {
	let max = 0;
	for (const c of encounter.combatants) {
		const match = /^c-(\d+)$/.exec(c.id);
		if (match) {
			const n = Number.parseInt(match[1], 10);
			if (n > max) max = n;
		}
	}
	return max;
}

export function useEncounter() {
	const [encounter, setEncounter] = useState<Encounter>(initializeEncounter);
	const [events, setEvents] = useState<DomainEvent[]>([]);
	const encounterRef = useRef(encounter);
	encounterRef.current = encounter;

	useEffect(() => {
		saveEncounter(encounter);
	}, [encounter]);

	const makeStore = useCallback((): EncounterStore => {
		return {
			get: () => encounterRef.current,
			save: (e) => setEncounter(e),
		};
	}, []);

	const advanceTurn = useCallback(() => {
		const result = advanceTurnUseCase(makeStore());

		if (isDomainError(result)) {
			return;
		}

		setEvents((prev) => [...prev, ...result]);
	}, [makeStore]);

	const nextId = useRef(deriveNextId(encounter));

	const addCombatant = useCallback(
		(name: string) => {
			const id = combatantId(`c-${++nextId.current}`);
			const result = addCombatantUseCase(makeStore(), id, name);

			if (isDomainError(result)) {
				return;
			}

			setEvents((prev) => [...prev, ...result]);
		},
		[makeStore],
	);

	const removeCombatant = useCallback(
		(id: CombatantId) => {
			const result = removeCombatantUseCase(makeStore(), id);

			if (isDomainError(result)) {
				return;
			}

			setEvents((prev) => [...prev, ...result]);
		},
		[makeStore],
	);

	const editCombatant = useCallback(
		(id: CombatantId, newName: string) => {
			const result = editCombatantUseCase(makeStore(), id, newName);

			if (isDomainError(result)) {
				return;
			}

			setEvents((prev) => [...prev, ...result]);
		},
		[makeStore],
	);

	const setInitiative = useCallback(
		(id: CombatantId, value: number | undefined) => {
			const result = setInitiativeUseCase(makeStore(), id, value);

			if (isDomainError(result)) {
				return;
			}

			setEvents((prev) => [...prev, ...result]);
		},
		[makeStore],
	);

	const setHp = useCallback(
		(id: CombatantId, maxHp: number | undefined) => {
			const result = setHpUseCase(makeStore(), id, maxHp);

			if (isDomainError(result)) {
				return;
			}

			setEvents((prev) => [...prev, ...result]);
		},
		[makeStore],
	);

	const adjustHp = useCallback(
		(id: CombatantId, delta: number) => {
			const result = adjustHpUseCase(makeStore(), id, delta);

			if (isDomainError(result)) {
				return;
			}

			setEvents((prev) => [...prev, ...result]);
		},
		[makeStore],
	);

	return {
		encounter,
		events,
		advanceTurn,
		addCombatant,
		removeCombatant,
		editCombatant,
		setInitiative,
		setHp,
		adjustHp,
	} as const;
}