import type { EncounterStore } from "@initiative/application";
import {
	addCombatantUseCase,
	adjustHpUseCase,
	advanceTurnUseCase,
	clearEncounterUseCase,
	editCombatantUseCase,
	removeCombatantUseCase,
	retreatTurnUseCase,
	setAcUseCase,
	setHpUseCase,
	setInitiativeUseCase,
	setTempHpUseCase,
	toggleConcentrationUseCase,
	toggleConditionUseCase,
} from "@initiative/application";
import type {
	BestiaryIndexEntry,
	CombatantId,
	ConditionId,
	CreatureId,
	DomainEvent,
	Encounter,
	PlayerCharacter,
} from "@initiative/domain";
import {
	combatantId,
	isDomainError,
	creatureId as makeCreatureId,
	resolveCreatureName,
} from "@initiative/domain";
import { useCallback, useEffect, useRef, useState } from "react";
import {
	loadEncounter,
	saveEncounter,
} from "../persistence/encounter-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;
}

interface CombatantOpts {
	initiative?: number;
	ac?: number;
	maxHp?: number;
}

function applyCombatantOpts(
	makeStore: () => EncounterStore,
	id: ReturnType<typeof combatantId>,
	opts: CombatantOpts,
): DomainEvent[] {
	const events: DomainEvent[] = [];
	if (opts.maxHp !== undefined) {
		const r = setHpUseCase(makeStore(), id, opts.maxHp);
		if (!isDomainError(r)) events.push(...r);
	}
	if (opts.ac !== undefined) {
		const r = setAcUseCase(makeStore(), id, opts.ac);
		if (!isDomainError(r)) events.push(...r);
	}
	if (opts.initiative !== undefined) {
		const r = setInitiativeUseCase(makeStore(), id, opts.initiative);
		if (!isDomainError(r)) events.push(...r);
	}
	return events;
}

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) => {
				encounterRef.current = e;
				setEncounter(e);
			},
		};
	}, []);

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

		if (isDomainError(result)) {
			return;
		}

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

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

		if (isDomainError(result)) {
			return;
		}

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

	const nextId = useRef(deriveNextId(encounter));

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

			if (isDomainError(result)) {
				return;
			}

			if (opts) {
				const optEvents = applyCombatantOpts(makeStore, id, opts);
				if (optEvents.length > 0) {
					setEvents((prev) => [...prev, ...optEvents]);
				}
			}

			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],
	);

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

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

			if (isDomainError(result)) {
				return;
			}

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

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

		if (isDomainError(result)) {
			return;
		}

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

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

			// Apply renames (e.g., "Goblin" → "Goblin 1")
			for (const { from, to } of renames) {
				const target = store.get().combatants.find((c) => c.name === from);
				if (target) {
					editCombatantUseCase(makeStore(), target.id, to);
				}
			}

			// Add combatant with resolved name
			const id = combatantId(`c-${++nextId.current}`);
			const addResult = addCombatantUseCase(makeStore(), id, newName);
			if (isDomainError(addResult)) return null;

			// Set HP
			const hpResult = setHpUseCase(makeStore(), id, entry.hp);
			if (!isDomainError(hpResult)) {
				setEvents((prev) => [...prev, ...hpResult]);
			}

			// Set AC
			if (entry.ac > 0) {
				const acResult = setAcUseCase(makeStore(), id, entry.ac);
				if (!isDomainError(acResult)) {
					setEvents((prev) => [...prev, ...acResult]);
				}
			}

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

			// Set creatureId on the combatant (use store.save to keep ref in sync for batch calls)
			const currentEncounter = store.get();
			store.save({
				...currentEncounter,
				combatants: currentEncounter.combatants.map((c) =>
					c.id === id ? { ...c, creatureId: cId } : c,
				),
			});

			setEvents((prev) => [...prev, ...addResult]);

			return cId;
		},
		[makeStore],
	);

	const addFromPlayerCharacter = useCallback(
		(pc: PlayerCharacter) => {
			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 addResult = addCombatantUseCase(makeStore(), id, newName);
			if (isDomainError(addResult)) return;

			// Set HP
			const hpResult = setHpUseCase(makeStore(), id, pc.maxHp);
			if (!isDomainError(hpResult)) {
				setEvents((prev) => [...prev, ...hpResult]);
			}

			// Set AC
			if (pc.ac > 0) {
				const acResult = setAcUseCase(makeStore(), id, pc.ac);
				if (!isDomainError(acResult)) {
					setEvents((prev) => [...prev, ...acResult]);
				}
			}

			// Set color, icon, and playerCharacterId on the combatant
			const currentEncounter = store.get();
			store.save({
				...currentEncounter,
				combatants: currentEncounter.combatants.map((c) =>
					c.id === id
						? {
								...c,
								color: pc.color,
								icon: pc.icon,
								playerCharacterId: pc.id,
							}
						: c,
				),
			});

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

	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,
		advanceTurn,
		retreatTurn,
		addCombatant,
		clearEncounter,
		removeCombatant,
		editCombatant,
		setInitiative,
		setHp,
		adjustHp,
		setTempHp,
		setAc,
		toggleCondition,
		toggleConcentration,
		addFromBestiary,
		addFromPlayerCharacter,
		makeStore,
	} as const;
}