import { existsSync, promises as fs } from "node:fs";
import os from "node:os";
import path from "node:path";
import { sql } from "drizzle-orm";
import { db } from "@/lib/db";
import { extractFurniIconPng } from "@/lib/services/clone-icon";
import {
	type CloneSource,
	DEFAULT_ICON_SOURCES,
	listSources,
} from "@/lib/services/clone-sources";
import {
	type FurniAssetWriteTargets,
	getFurniAssetWriteTargets,
} from "@/lib/services/furni-asset-dirs";
import { downloadFile } from "@/lib/services/import/core/download";
import { ensureDirectories } from "./furni-import";

const REPAIR_CONCURRENCY = 6;

/** Sliding-window worker pool: keeps up to `concurrency` tasks in flight. */
async function runPool<T>(
	items: T[],
	concurrency: number,
	worker: (item: T, index: number) => Promise<void>,
): Promise<void> {
	const limit = Math.min(Math.max(concurrency, 1), items.length);
	if (limit === 0) return;
	let next = 0;
	await Promise.allSettled(
		Array.from({ length: limit }, async () => {
			while (true) {
				const i = next++;
				if (i >= items.length) break;
				await worker(items[i], i);
			}
		}),
	);
}

function uniqueDirs(dirs: string[]): string[] {
	const seen = new Set<string>();
	const out: string[] = [];
	for (const dir of dirs) {
		const key = process.platform === "win32" ? dir.toLowerCase() : dir;
		if (seen.has(key)) continue;
		seen.add(key);
		out.push(dir);
	}
	return out;
}

async function writeIconToDirs(
	icon: Buffer,
	dirs: string[],
	fileName: string,
): Promise<string[]> {
	const errors: string[] = [];
	for (const dir of dirs) {
		try {
			await fs.mkdir(dir, { recursive: true });
			await fs.writeFile(path.join(dir, fileName), icon);
		} catch (err) {
			errors.push(`write icon to ${dir} failed: ${(err as Error).message}`);
		}
	}
	return errors;
}

async function copyIconAcrossDirs(
	srcDir: string,
	destDirs: string[],
	fileName: string,
): Promise<string[]> {
	const errors: string[] = [];
	const src = path.join(srcDir, fileName);
	for (const dir of destDirs) {
		if (dir === srcDir) continue;
		try {
			await fs.mkdir(dir, { recursive: true });
			await fs.copyFile(src, path.join(dir, fileName));
		} catch (err) {
			errors.push(`copy icon to ${dir} failed: ${(err as Error).message}`);
		}
	}
	return errors;
}

export interface RepairEvent {
	type: "started" | "progress" | "done" | "batch_complete" | "error";
	classname?: string;
	status?: string;
	index?: number;
	total?: number;
	message?: string;
	warnings?: string[];
	succeeded?: number;
	failed?: number;
	skipped?: number;
	duration?: number;
}

export async function repairMissingIcons(
	onEvent?: (evt: RepairEvent) => void,
): Promise<{ succeeded: number; failed: number; skipped: number }> {
	let succeeded = 0;
	let failed = 0;
	let skipped = 0;

	try {
		await ensureDirectories();
	} catch (err) {
		onEvent?.({
			type: "error",
			message: `ensureDirectories failed: ${(err as Error).message}`,
		});
		return { succeeded: 0, failed: 0, skipped: 0 };
	}

	let targets: FurniAssetWriteTargets;
	try {
		targets = await getFurniAssetWriteTargets();
	} catch (err) {
		onEvent?.({
			type: "error",
			message: `getFurniAssetWriteTargets failed: ${(err as Error).message}`,
		});
		return { succeeded: 0, failed: 0, skipped: 0 };
	}

	// Every location the app mirrors furni assets into — the webroot (public/)
	// plus the live gamedata (e.g. /var/www/Gamedata). Repair writes to all of
	// them so both the CMS and the client see the icon.
	const iconDirs = uniqueDirs([
		targets.iconDir,
		...targets.mirrorDirs.map((d) => d.iconDir),
	]);
	const nitroDirs = uniqueDirs([
		targets.nitroDir,
		...targets.mirrorDirs.map((d) => d.nitroDir),
	]);

	let items: Array<{ id: number; item_name: string }>;
	try {
		const [rows] = (await db.execute(sql`
			SELECT id, item_name FROM items_base ORDER BY id
		`)) as unknown as [Array<{ id: number; item_name: string }>, unknown];
		items = rows;
	} catch (err) {
		onEvent?.({
			type: "error",
			message: `Database query failed: ${(err as Error).message}`,
		});
		return { succeeded: 0, failed: 0, skipped: 0 };
	}

	const total = items.length;
	onEvent?.({ type: "started", total });

	const processItem = async (classname: string) => {
		const fileName = `${classname}_icon.png`;

		// Badge items store icons as badge_<code>_icon.png (the classname already
		// includes the `badge_` prefix, so fileName matches correctly).
		const presentDirs = iconDirs.filter((dir) =>
			existsSync(path.join(dir, fileName)),
		);
		const missingDirs = iconDirs.filter((dir) => !presentDirs.includes(dir));

		if (missingDirs.length === 0) {
			return { status: "skipped" } as const;
		}

		let ok = false;
		const warnings: string[] = [];

		// 1) Copy across mirrors — the icon already exists in one target (e.g.
		// gamedata), so just fill the ones that are missing it.
		if (presentDirs.length > 0) {
			try {
				const copyErrors = await copyIconAcrossDirs(
					presentDirs[0],
					missingDirs,
					fileName,
				);
				warnings.push(...copyErrors);
				ok = copyErrors.length === 0;
			} catch (err) {
				warnings.push(
					`copy across icon dirs failed: ${(err as Error).message}`,
				);
			}
		}

		// 2) Extract from a local .nitro bundle (checked across every target).
		if (!ok) {
			let foundNitro = false;
			for (const dir of nitroDirs) {
				const nitroPath = path.join(dir, `${classname}.nitro`);
				if (!existsSync(nitroPath)) continue;
				foundNitro = true;
				try {
					const nitroBuf = await fs.readFile(nitroPath);
					const icon = extractFurniIconPng(nitroBuf);
					if (icon) {
						const writeErrors = await writeIconToDirs(
							icon,
							missingDirs,
							fileName,
						);
						warnings.push(...writeErrors);
						ok = writeErrors.length === 0;
						break;
					}
					warnings.push("no icon asset in .nitro bundle");
				} catch (err) {
					warnings.push(
						`extract from .nitro failed: ${(err as Error).message}`,
					);
				}
			}
			if (!foundNitro) warnings.push(".nitro file not found on disk");
		}

		// 3) Download from configured or default public sources.
		if (!ok) {
			let sources: CloneSource[] = [];
			try {
				sources = (await listSources()).filter(
					(s) => s.iconBaseUrl || s.nitroBaseUrl,
				);
			} catch (err) {
				warnings.push(`listSources failed: ${(err as Error).message}`);
			}
			if (sources.length === 0) sources = DEFAULT_ICON_SOURCES;

			for (const source of sources) {
				const iconCandidates = [
					`${classname}_icon.png`,
					// Variant classnames (e.g. `table_silo_med*10`) often only exist
					// on sources under their base name (e.g. `table_silo_med_icon.png`)
					// or with the `*` replaced by `_` (e.g. `table_silo_med_10_icon.png`).
					...(classname.includes("*")
						? [
								`${classname.split("*")[0]}_icon.png`,
								`${classname.replace(/\*/g, "_")}_icon.png`,
							]
						: []),
				];

				for (const iconName of iconCandidates) {
					try {
						const dl = await downloadFile(
							`${source.iconBaseUrl}/${iconName}`,
							path.join(targets.iconDir, fileName),
							{ maxRetries: 1, validate: "png" },
						);
						if (dl.ok) {
							const icon = await fs.readFile(
								path.join(targets.iconDir, fileName),
							);
							const writeErrors = await writeIconToDirs(
								icon,
								missingDirs,
								fileName,
							);
							warnings.push(...writeErrors);
							ok = writeErrors.length === 0;
							break;
						}
						warnings.push(`${iconName} not found on ${source.name}`);
					} catch (err) {
						warnings.push(
							`download from ${source.name} failed: ${(err as Error).message}`,
						);
					}
				}
				if (ok) break;

				// Some sources only ship icons embedded in their `.nitro` bundles —
				// grab the bundle and extract the catalog icon from it.
				if (source.nitroBaseUrl) {
					const nitroTmp = path.join(os.tmpdir(), `.repair_${classname}.nitro`);
					try {
						const dl = await downloadFile(
							`${source.nitroBaseUrl}/${classname}.nitro`,
							nitroTmp,
							{ maxRetries: 1 },
						);
						if (dl.ok) {
							const icon = extractFurniIconPng(await fs.readFile(nitroTmp));
							if (icon) {
								const writeErrors = await writeIconToDirs(
									icon,
									missingDirs,
									fileName,
								);
								warnings.push(...writeErrors);
								ok = writeErrors.length === 0;
							} else {
								warnings.push(`no icon asset in ${source.name} .nitro bundle`);
							}
						} else {
							warnings.push(`.nitro not found on ${source.name}`);
						}
					} catch (err) {
						warnings.push(
							`extract from ${source.name} .nitro failed: ${(err as Error).message}`,
						);
					} finally {
						await fs.unlink(nitroTmp).catch(() => {});
					}
					if (ok) break;
				}
			}
		}

		if (ok) {
			return { status: "done", warnings } as const;
		}
		return {
			status: "failed",
			message: warnings[0] || "could not obtain icon",
		} as const;
	};

	await runPool(items, REPAIR_CONCURRENCY, async (item, i) => {
		const classname = item.item_name;
		const result = await processItem(classname);
		if (result.status === "skipped") {
			skipped++;
			onEvent?.({
				type: "progress",
				classname,
				status: "skipped",
				index: i,
				total,
			});
			return;
		}
		if (result.status === "done") {
			succeeded++;
			onEvent?.({
				type: "progress",
				classname,
				status: "done",
				index: i,
				total,
				warnings: result.warnings.length ? result.warnings : undefined,
			});
			return;
		}
		failed++;
		onEvent?.({
			type: "progress",
			classname,
			status: "failed",
			index: i,
			total,
			message: result.message,
		});
	});

	onEvent?.({
		type: "batch_complete",
		succeeded,
		failed,
		skipped,
	});

	return { succeeded, failed, skipped };
}