export type SnippetType = "block" | "inline";

export type Snippet = {
	id: number;
	type: SnippetType;
	language?: string;
	content: string;
	messageId: string;
	sourceLabel: string;
};

// ─────────────────────────────────────────────────────────────
// Constants
// ─────────────────────────────────────────────────────────────

/** Minimum slashes required for generic path-like content (e.g. `foo/bar/baz`) */
const MIN_SLASH_COUNT = 2;

/** Matches file extensions like .ts, .html, .json */
const HAS_FILE_EXTENSION = /\.[a-zA-Z0-9]{1,6}$/;

/** Commands/keywords that appear in inline code but aren't actionable */
const IGNORED_COMMANDS = new Set([
	"main",
	"inline",
	"blocks",
	"bash -lc",
	"ls",
	"pwd",
	"cd",
	"git status",
	"git diff",
	"git add",
	"git commit",
	"git push",
	"git pull",
	"git checkout",
	"git switch",
	"npm install",
	"pnpm install",
	"yarn install",
	"bun install",
	"npm test",
	"pnpm test",
	"yarn test",
	"npm run",
	"pnpm run",
	"yarn run",
	"make",
	"make test",
	"make lint",
	"make build",
]);

export function extractText(content: unknown): string {
	if (typeof content === "string") return content;
	if (!Array.isArray(content)) return "";

	let text = "";
	for (const part of content) {
		if (part && typeof part === "object" && (part as { type?: string }).type === "text") {
			const value = (part as { text?: string }).text;
			if (value) text += value;
		}
	}

	return text;
}

// ─────────────────────────────────────────────────────────────
// Filtering
// ─────────────────────────────────────────────────────────────

/** Check if content looks like a file path worth extracting */
function looksLikePath(content: string): boolean {
	const slashCount = (content.match(/\//g) || []).length;

	// ~/... or commands containing ~/ (e.g. "open ~/file.html")
	if (/(?:^|[\s"'])~\//.test(content)) return true;

	// ./... (current directory)
	if (content.startsWith("./")) return true;

	// Absolute paths: /foo/bar (2+ slashes) or /file.html (has extension)
	if (content.startsWith("/")) {
		return slashCount >= MIN_SLASH_COUNT || HAS_FILE_EXTENSION.test(content);
	}

	// Generic: foo/bar/baz requires 2+ slashes
	return slashCount >= MIN_SLASH_COUNT;
}

function shouldIncludeInlineSnippet(content: string): boolean {
	const trimmed = content.trim();

	// Reject: empty, comments, known commands, short identifiers
	if (trimmed.length === 0) return false;
	if (trimmed.startsWith("//") || trimmed.startsWith("/*") || trimmed.startsWith("*")) return false;
	if (IGNORED_COMMANDS.has(trimmed)) return false;
	if (/^[A-Za-z0-9._-]{1,5}$/.test(trimmed)) return false;

	return looksLikePath(trimmed);
}

// ─────────────────────────────────────────────────────────────
// Extraction
// ─────────────────────────────────────────────────────────────

export function extractSnippets(
	text: string,
	messageId: string,
	sourceLabel: string,
	startId: number,
	includeInline: boolean,
	limit: number,
): Snippet[] {
	const snippets: Snippet[] = [];
	const fencedRanges: Array<{ start: number; end: number }> = [];
	const fencedRegex = /```([^\n`]*)\n([\s\S]*?)```/g;
	let match: RegExpExecArray | null;

	while ((match = fencedRegex.exec(text))) {
		if (snippets.length >= limit) return snippets;
		const language = match[1]?.trim() || undefined;
		const content = match[2]?.replace(/\n$/, "") ?? "";
		snippets.push({
			id: startId + snippets.length,
			type: "block",
			language,
			content,
			messageId,
			sourceLabel,
		});
		fencedRanges.push({ start: match.index, end: match.index + match[0].length });
	}

	if (!includeInline) return snippets;

	const inlineRegex = /`([^`\n]+)`/g;
	while ((match = inlineRegex.exec(text))) {
		if (snippets.length >= limit) return snippets;
		const index = match.index;
		const inFence = fencedRanges.some((range) => index >= range.start && index < range.end);
		if (inFence) continue;

		const content = match[1] ?? "";
		if (!shouldIncludeInlineSnippet(content)) continue;

		snippets.push({
			id: startId + snippets.length,
			type: "inline",
			content,
			messageId,
			sourceLabel,
		});
	}

	return snippets;
}

export function getSnippetPreview(snippet: Snippet): string {
	const content = snippet.content.trim();
	if (content.length === 0) return "(empty)";

	if (snippet.type === "block") {
		return content.replace(/\s+/g, " ");
	}

	const lines = content.split(/\r?\n/);
	const firstNonEmpty = lines.find((line) => line.trim().length > 0) ?? lines[0] ?? "";
	const preview = firstNonEmpty.trim();
	return preview.length > 0 ? preview : "(empty)";
}

export function truncatePreview(value: string, width: number): string {
	if (value.length <= width) return value;
	if (width <= 1) return value.slice(0, width);
	return `${value.slice(0, width - 1)}…`;
}