import { readFileSync } from "node:fs";
import { join, resolve } from "node:path";
import type { ToolInfo } from "@earendil-works/pi-coding-agent";

const CODEX_PACKAGE_NAME = "@howaboua/pi-codex-conversion";
const CODEX_NPM_SOURCE_PREFIX = `npm:${CODEX_PACKAGE_NAME}`;
const NON_LOCAL_SOURCE_PREFIXES = ["npm:", "git:", "github:", "http:", "https:", "ssh:"] as const;

export interface InheritedExtensionMetadata {
	extensionPaths: string[];
	inheritedToolNames: string[];
}

function isLocalPackageSource(source: unknown): source is string {
	if (typeof source !== "string") {
		return false;
	}
	const value = source.trim();
	return !NON_LOCAL_SOURCE_PREFIXES.some((prefix) => value.startsWith(prefix));
}

function hasNamedPackageManifest(baseDir: unknown): boolean {
	if (typeof baseDir !== "string" || baseDir.trim() === "") {
		return false;
	}
	try {
		const manifest = JSON.parse(readFileSync(join(baseDir, "package.json"), "utf8")) as unknown;
		return (
			manifest !== null &&
			typeof manifest === "object" &&
			"name" in manifest &&
			(manifest as { name?: unknown }).name === CODEX_PACKAGE_NAME
		);
	} catch {
		return false;
	}
}

function isCodexConversionTool(tool: ToolInfo): boolean {
	const sourceInfo = tool.sourceInfo;
	if (sourceInfo?.origin !== "package") {
		return false;
	}
	if (
		typeof sourceInfo.source === "string" &&
		(sourceInfo.source.trim() === CODEX_NPM_SOURCE_PREFIX ||
			sourceInfo.source.trim().startsWith(`${CODEX_NPM_SOURCE_PREFIX}@`))
	) {
		return true;
	}
	return isLocalPackageSource(sourceInfo.source) && hasNamedPackageManifest(sourceInfo.baseDir);
}

export function collectInheritedExtensionMetadata(
	allTools: readonly ToolInfo[],
	activeToolNames: readonly string[],
	ownExtensionPath: string,
): InheritedExtensionMetadata {
	const activeNames = new Set(activeToolNames);
	const extensionPaths = new Set<string>();
	const inheritedToolNames = new Set<string>();
	const resolvedOwnExtensionPath = resolve(ownExtensionPath);

	for (const tool of allTools) {
		const sourcePath = tool.sourceInfo?.path;
		if (typeof sourcePath !== "string" || sourcePath.trim() === "" || sourcePath.startsWith("<")) {
			continue;
		}
		if (resolve(sourcePath) === resolvedOwnExtensionPath) {
			continue;
		}

		const isConversionTool = isCodexConversionTool(tool);
		if (isConversionTool) {
			extensionPaths.add(sourcePath);
			inheritedToolNames.add(tool.name);
			continue;
		}
		if (activeNames.has(tool.name)) {
			extensionPaths.add(sourcePath);
		}
	}

	return {
		extensionPaths: [...extensionPaths],
		inheritedToolNames: [...inheritedToolNames],
	};
}