import type { EncounterStore, UndoRedoStore } from "@initiative/application";
import {
	addCombatantUseCase,
	adjustHpUseCase,
	advanceTurnUseCase,
	clearEncounterUseCase,
	editCombatantUseCase,
	redoUseCase,
	removeCombatantUseCase,
	retreatTurnUseCase,
	setAcUseCase,
	setHpUseCase,
	setInitiativeUseCase,
	setTempHpUseCase,
	toggleConcentrationUseCase,
	toggleConditionUseCase,
	undoUseCase,
} from "@initiative/application";
import type {
	BestiaryIndexEntry,
	CombatantId,
	CombatantInit,
	ConditionId,
	CreatureId,
	DomainEvent,
	Encounter,
	PlayerCharacter,
	UndoRedoState,
} from "@initiative/domain";
import {
	clearHistory,
	combatantId,
	isDomainError,
	creatureId as makeCreatureId,
	pushUndo,
	resolveCreatureName,
} from "@initiative/domain";
import { useCallback, useEffect, useRef, useState } from "react";
import {
	loadEncounter,
	saveEncounter,
} from "../persistence/encounter-storage.js";
import {
	loadUndoRedoStacks,
	saveUndoRedoStacks,
} from "../persistence/undo-redo-storage.js";

const COMBATANT_ID_REGEX = /^c-(\d+)$/;

const EMPTY_ENCOUNTER: Encounter = {
	combatants: [],
	activeIndex: 0,
	roundNumber: 1,
};

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

function deriveNextId(encounter: Encounter): number {
	let max = 0;
	for (const c of encounter.combatants) {
		const match = COMBATANT_ID_REGEX.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 [undoRedoState, setUndoRedoState] =
		useState<UndoRedoState>(loadUndoRedoStacks);
	const encounterRef = useRef(encounter);
	encounterRef.current = encounter;
	const undoRedoRef = useRef(undoRedoState);
	undoRedoRef.current = undoRedoState;

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

	useEffect(() => {
		saveUndoRedoStacks(undoRedoState);
	}, [undoRedoState]);

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

	const makeUndoRedoStore = useCallback((): UndoRedoStore => {
		return {
			get: () => undoRedoRef.current,
			save: (s) => {
				undoRedoRef.current = s;
				setUndoRedoState(s);
			},
		};
	}, []);

	const withUndo = useCallback(<T>(action: () => T): T => {
		const snapshot = encounterRef.current;
		const result = action();
		if (!isDomainError(result)) {
			const newState = pushUndo(undoRedoRef.current, snapshot);
			undoRedoRef.current = newState;
			setUndoRedoState(newState);
		}
		return result;
	}, []);

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

		if (isDomainError(result)) {
			return;
		}

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

	const retreatTurn = useCallback(() => {
		const result = withUndo(() => retreatTurnUseCase(makeStore()));

		if (isDomainError(result)) {
			return;
		}

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

	const nextId = useRef(deriveNextId(encounter));

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

	const setTempHp = useCallback(
		(id: CombatantId, tempHp: number | undefined) => {
			const result = withUndo(() => setTempHpUseCase(makeStore(), id, tempHp));

			if (isDomainError(result)) {
				return;
			}

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

	const setAc = useCallback(
		(id: CombatantId, value: number | undefined) => {
			const result = withUndo(() => setAcUseCase(makeStore(), id, value));

			if (isDomainError(result)) {
				return;
			}

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

	const toggleCondition = useCallback(
		(id: CombatantId, conditionId: ConditionId) => {
			const result = withUndo(() =>
				toggleConditionUseCase(makeStore(), id, conditionId),
			);

			if (isDomainError(result)) {
				return;
			}

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

	const toggleConcentration = useCallback(
		(id: CombatantId) => {
			const result = withUndo(() =>
				toggleConcentrationUseCase(makeStore(), id),
			);

			if (isDomainError(result)) {
				return;
			}

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

	const clearEncounter = useCallback(() => {
		const result = clearEncounterUseCase(makeStore());

		if (isDomainError(result)) {
			return;
		}

		const cleared = clearHistory();
		undoRedoRef.current = cleared;
		setUndoRedoState(cleared);

		nextId.current = 0;
		setEvents((prev) => [...prev, ...result]);
	}, [makeStore]);

	const addFromBestiary = useCallback(
		(entry: BestiaryIndexEntry): CreatureId | null => {
			const snapshot = encounterRef.current;
			const store = makeStore();
			const existingNames = store.get().combatants.map((c) => c.name);
			const { newName, renames } = resolveCreatureName(
				entry.name,
				existingNames,
			);

			for (const { from, to } of renames) {
				const target = store.get().combatants.find((c) => c.name === from);
				if (target) {
					editCombatantUseCase(makeStore(), target.id, to);
				}
			}

			const slug = entry.name
				.toLowerCase()
				.replaceAll(/[^a-z0-9]+/g, "-")
				.replaceAll(/(^-|-$)/g, "");
			const cId = makeCreatureId(`${entry.source.toLowerCase()}:${slug}`);

			const id = combatantId(`c-${++nextId.current}`);
			const result = addCombatantUseCase(makeStore(), id, newName, {
				maxHp: entry.hp,
				ac: entry.ac > 0 ? entry.ac : undefined,
				creatureId: cId,
			});

			if (isDomainError(result)) {
				store.save(snapshot);
				return null;
			}

			const newState = pushUndo(undoRedoRef.current, snapshot);
			undoRedoRef.current = newState;
			setUndoRedoState(newState);

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

	const addFromPlayerCharacter = useCallback(
		(pc: PlayerCharacter) => {
			const snapshot = encounterRef.current;
			const store = makeStore();
			const existingNames = store.get().combatants.map((c) => c.name);
			const { newName, renames } = resolveCreatureName(pc.name, existingNames);

			for (const { from, to } of renames) {
				const target = store.get().combatants.find((c) => c.name === from);
				if (target) {
					editCombatantUseCase(makeStore(), target.id, to);
				}
			}

			const id = combatantId(`c-${++nextId.current}`);
			const result = addCombatantUseCase(makeStore(), id, newName, {
				maxHp: pc.maxHp,
				ac: pc.ac > 0 ? pc.ac : undefined,
				color: pc.color,
				icon: pc.icon,
				playerCharacterId: pc.id,
			});

			if (isDomainError(result)) {
				store.save(snapshot);
				return;
			}

			const newState = pushUndo(undoRedoRef.current, snapshot);
			undoRedoRef.current = newState;
			setUndoRedoState(newState);

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

	const undoAction = useCallback(() => {
		undoUseCase(makeStore(), makeUndoRedoStore());
	}, [makeStore, makeUndoRedoStore]);

	const redoAction = useCallback(() => {
		redoUseCase(makeStore(), makeUndoRedoStore());
	}, [makeStore, makeUndoRedoStore]);

	const canUndo = undoRedoState.undoStack.length > 0;
	const canRedo = undoRedoState.redoStack.length > 0;

	const hasTempHp = encounter.combatants.some(
		(c) => c.tempHp !== undefined && c.tempHp > 0,
	);

	const isEmpty = encounter.combatants.length === 0;
	const hasCreatureCombatants = encounter.combatants.some(
		(c) => c.creatureId != null,
	);
	const canRollAllInitiative = encounter.combatants.some(
		(c) => c.creatureId != null && c.initiative == null,
	);

	return {
		encounter,
		events,
		isEmpty,
		hasTempHp,
		hasCreatureCombatants,
		canRollAllInitiative,
		canUndo,
		canRedo,
		advanceTurn,
		retreatTurn,
		addCombatant,
		clearEncounter,
		removeCombatant,
		editCombatant,
		setInitiative,
		setHp,
		adjustHp,
		setTempHp,
		setAc,
		toggleCondition,
		toggleConcentration,
		addFromBestiary,
		addFromPlayerCharacter,
		undo: undoAction,
		redo: redoAction,
		makeStore,
	} as const;
}