import type {
	AnyCreature,
	BestiaryIndexEntry,
	CreatureId,
	Pf2eBestiaryIndexEntry,
} from "@initiative/domain";
import { useCallback, useEffect, useState } from "react";
import {
	normalizeBestiary,
	setSourceDisplayNames,
} from "../adapters/bestiary-adapter.js";
import { normalizeFoundryCreatures } from "../adapters/pf2e-bestiary-adapter.js";
import { useAdapters } from "../contexts/adapter-context.js";
import { useRulesEditionContext } from "../contexts/rules-edition-context.js";

export type SearchResult =
	| (BestiaryIndexEntry & {
			readonly system: "dnd";
			readonly sourceDisplayName: string;
	  })
	| (Pf2eBestiaryIndexEntry & {
			readonly system: "pf2e";
			readonly sourceDisplayName: string;
	  });

interface BestiaryHook {
	search: (query: string) => SearchResult[];
	getCreature: (id: CreatureId) => AnyCreature | undefined;
	isLoaded: boolean;
	isSourceCached: (sourceCode: string) => Promise<boolean>;
	fetchAndCacheSource: (
		sourceCode: string,
		url: string,
	) => Promise<{ skippedNames: string[] }>;
	uploadAndCacheSource: (
		sourceCode: string,
		jsonData: unknown,
	) => Promise<void>;
	refreshCache: () => Promise<void>;
}

interface BatchResult {
	readonly responses: unknown[];
	readonly failed: string[];
}

async function fetchJson(url: string, path: string): Promise<unknown> {
	const response = await fetch(url);
	if (!response.ok) {
		throw new Error(
			`Failed to fetch ${path}: ${response.status} ${response.statusText}`,
		);
	}
	return response.json();
}

async function fetchWithRetry(
	url: string,
	path: string,
	retries = 2,
): Promise<unknown> {
	try {
		return await fetchJson(url, path);
	} catch (error) {
		if (retries <= 0) throw error;
		await new Promise<void>((r) => setTimeout(r, 500));
		return fetchWithRetry(url, path, retries - 1);
	}
}

async function fetchBatch(
	baseUrl: string,
	paths: string[],
): Promise<BatchResult> {
	const settled = await Promise.allSettled(
		paths.map((path) => fetchWithRetry(`${baseUrl}${path}`, path)),
	);
	const responses: unknown[] = [];
	const failed: string[] = [];
	for (let i = 0; i < settled.length; i++) {
		const result = settled[i];
		if (result.status === "fulfilled") {
			responses.push(result.value);
		} else {
			failed.push(paths[i]);
		}
	}
	return { responses, failed };
}

async function fetchInBatches(
	paths: string[],
	baseUrl: string,
	concurrency: number,
): Promise<BatchResult> {
	const batches: string[][] = [];
	for (let i = 0; i < paths.length; i += concurrency) {
		batches.push(paths.slice(i, i + concurrency));
	}
	const accumulated = await batches.reduce<Promise<BatchResult>>(
		async (prev, batch) => {
			const acc = await prev;
			const result = await fetchBatch(baseUrl, batch);
			return {
				responses: [...acc.responses, ...result.responses],
				failed: [...acc.failed, ...result.failed],
			};
		},
		Promise.resolve({ responses: [], failed: [] }),
	);
	return accumulated;
}

interface Pf2eFetchResult {
	creatures: AnyCreature[];
	skippedNames: string[];
}

async function fetchPf2eSource(
	paths: string[],
	url: string,
	sourceCode: string,
	displayName: string,
	resolveNames: (failedPaths: string[]) => Map<string, string>,
): Promise<Pf2eFetchResult> {
	const baseUrl = url.endsWith("/") ? url : `${url}/`;
	const { responses, failed } = await fetchInBatches(paths, baseUrl, 6);
	if (responses.length === 0) {
		throw new Error(
			`Failed to fetch any creatures (${failed.length} failed). This may be caused by an ad blocker — try disabling it for this site or use file upload instead.`,
		);
	}
	const nameMap = failed.length > 0 ? resolveNames(failed) : new Map();
	const skippedNames = failed.map((p) => nameMap.get(p) ?? p);
	if (skippedNames.length > 0) {
		console.warn("Skipped creatures (ad blocker?):", skippedNames);
	}
	return {
		creatures: normalizeFoundryCreatures(responses, sourceCode, displayName),
		skippedNames,
	};
}

export function useBestiary(): BestiaryHook {
	const { bestiaryCache, bestiaryIndex, pf2eBestiaryIndex } = useAdapters();
	const { edition } = useRulesEditionContext();
	const [isLoaded, setIsLoaded] = useState(false);
	const [creatureMap, setCreatureMap] = useState(
		() => new Map<CreatureId, AnyCreature>(),
	);

	useEffect(() => {
		const index = bestiaryIndex.loadIndex();
		setSourceDisplayNames(index.sources as Record<string, string>);

		const pf2eIndex = pf2eBestiaryIndex.loadIndex();

		if (index.creatures.length > 0 || pf2eIndex.creatures.length > 0) {
			setIsLoaded(true);
		}

		void bestiaryCache.loadAllCachedCreatures().then((map) => {
			setCreatureMap(map);
		});
	}, [bestiaryCache, bestiaryIndex, pf2eBestiaryIndex]);

	const search = useCallback(
		(query: string): SearchResult[] => {
			if (query.length < 2) return [];
			const lower = query.toLowerCase();

			if (edition === "pf2e") {
				const index = pf2eBestiaryIndex.loadIndex();
				return index.creatures
					.filter((c) => c.name.toLowerCase().includes(lower))
					.sort((a, b) => a.name.localeCompare(b.name))
					.slice(0, 10)
					.map((c) => ({
						...c,
						system: "pf2e" as const,
						sourceDisplayName: pf2eBestiaryIndex.getSourceDisplayName(c.source),
					}));
			}

			const index = bestiaryIndex.loadIndex();
			return index.creatures
				.filter((c) => c.name.toLowerCase().includes(lower))
				.sort((a, b) => a.name.localeCompare(b.name))
				.slice(0, 10)
				.map((c) => ({
					...c,
					system: "dnd" as const,
					sourceDisplayName: bestiaryIndex.getSourceDisplayName(c.source),
				}));
		},
		[bestiaryIndex, pf2eBestiaryIndex, edition],
	);

	const getCreature = useCallback(
		(id: CreatureId): AnyCreature | undefined => {
			return creatureMap.get(id);
		},
		[creatureMap],
	);

	const system = edition === "pf2e" ? "pf2e" : "dnd";

	const isSourceCachedFn = useCallback(
		(sourceCode: string): Promise<boolean> => {
			return bestiaryCache.isSourceCached(system, sourceCode);
		},
		[bestiaryCache, system],
	);

	const fetchAndCacheSource = useCallback(
		async (
			sourceCode: string,
			url: string,
		): Promise<{ skippedNames: string[] }> => {
			let creatures: AnyCreature[];
			let skippedNames: string[] = [];

			if (edition === "pf2e") {
				const paths = pf2eBestiaryIndex.getCreaturePathsForSource(sourceCode);
				const displayName = pf2eBestiaryIndex.getSourceDisplayName(sourceCode);
				const result = await fetchPf2eSource(
					paths,
					url,
					sourceCode,
					displayName,
					pf2eBestiaryIndex.getCreatureNamesByPaths,
				);
				creatures = result.creatures;
				skippedNames = result.skippedNames;
			} else {
				const response = await fetch(url);
				if (!response.ok) {
					throw new Error(
						`Failed to fetch: ${response.status} ${response.statusText}`,
					);
				}
				const json = await response.json();
				creatures = normalizeBestiary(json);
			}

			const displayName =
				edition === "pf2e"
					? pf2eBestiaryIndex.getSourceDisplayName(sourceCode)
					: bestiaryIndex.getSourceDisplayName(sourceCode);
			await bestiaryCache.cacheSource(
				system,
				sourceCode,
				displayName,
				creatures,
			);
			setCreatureMap((prev) => {
				const next = new Map(prev);
				for (const c of creatures) {
					next.set(c.id, c);
				}
				return next;
			});
			return { skippedNames };
		},
		[bestiaryCache, bestiaryIndex, pf2eBestiaryIndex, edition, system],
	);

	const uploadAndCacheSource = useCallback(
		async (sourceCode: string, jsonData: unknown): Promise<void> => {
			const creatures =
				edition === "pf2e"
					? normalizeFoundryCreatures(
							Array.isArray(jsonData) ? jsonData : [jsonData],
							sourceCode,
							pf2eBestiaryIndex.getSourceDisplayName(sourceCode),
						)
					: normalizeBestiary(
							jsonData as Parameters<typeof normalizeBestiary>[0],
						);
			const displayName =
				edition === "pf2e"
					? pf2eBestiaryIndex.getSourceDisplayName(sourceCode)
					: bestiaryIndex.getSourceDisplayName(sourceCode);
			await bestiaryCache.cacheSource(
				system,
				sourceCode,
				displayName,
				creatures,
			);
			setCreatureMap((prev) => {
				const next = new Map(prev);
				for (const c of creatures) {
					next.set(c.id, c);
				}
				return next;
			});
		},
		[bestiaryCache, bestiaryIndex, pf2eBestiaryIndex, edition, system],
	);

	const refreshCache = useCallback(async (): Promise<void> => {
		const map = await bestiaryCache.loadAllCachedCreatures();
		setCreatureMap(map);
	}, [bestiaryCache]);

	return {
		search,
		getCreature,
		isLoaded,
		isSourceCached: isSourceCachedFn,
		fetchAndCacheSource,
		uploadAndCacheSource,
		refreshCache,
	};
}