import {
	closeSync,
	existsSync,
	openSync,
	readdirSync,
	readFileSync,
	readSync,
	statSync,
	unwatchFile,
	watchFile,
} from "node:fs";
import { homedir } from "node:os";
import { basename, join } from "node:path";

export type LogSourceName = "notif" | "session" | "activity" | "audit";

export interface MergedLogEvent {
	source: LogSourceName;
	timestamp: string;
	message: string;
	severity?: string;
	filePath: string;
}

interface SourceFile {
	source: LogSourceName;
	path: string;
}

export interface CollectRecentLogOptions {
	basePath: string;
	sfHome?: string;
	source?: LogSourceName;
	severity?: string;
	limit?: number;
}

interface TailOptions extends CollectRecentLogOptions {
	stdout?: Pick<typeof process.stdout, "write">;
	stderr?: Pick<typeof process.stderr, "write">;
}

interface ParsedLogsArgs {
	command: "tail" | "follow";
	source?: LogSourceName;
	severity?: string;
}

const SOURCE_ALIASES: Record<string, LogSourceName> = {
	notif: "notif",
	notification: "notif",
	notifications: "notif",
	session: "session",
	sessions: "session",
	activity: "activity",
	audit: "audit",
};

function normalizeSource(value: string | undefined): LogSourceName | undefined {
	if (!value) return undefined;
	return SOURCE_ALIASES[value.toLowerCase()];
}

function sfHomeFromEnv(): string {
	return process.env.SF_HOME || join(homedir(), ".sf");
}

export function getProjectSessionKey(basePath: string): string {
	return `--${basePath.replace(/^[/\\]/, "").replace(/[/\\:]/g, "-")}--`;
}

function latestJsonlFile(dir: string): string | null {
	if (!existsSync(dir)) return null;
	try {
		const candidates = readdirSync(dir)
			.filter((file) => file.endsWith(".jsonl"))
			.map((file) => {
				const path = join(dir, file);
				try {
					const stat = statSync(path);
					return { path, mtimeMs: stat.mtimeMs };
				} catch {
					return null;
				}
			})
			.filter(
				(entry): entry is { path: string; mtimeMs: number } => entry !== null,
			);
		candidates.sort(
			(a, b) =>
				b.mtimeMs - a.mtimeMs ||
				basename(b.path).localeCompare(basename(a.path)),
		);
		return candidates[0]?.path ?? null;
	} catch {
		return null;
	}
}

function resolveSourceFiles(basePath: string, sfHome: string): SourceFile[] {
	const sfDir = join(basePath, ".sf");
	const sessionKey = getProjectSessionKey(basePath);
	const sessionFile =
		latestJsonlFile(join(sfHome, "agent", "sessions", sessionKey)) ??
		latestJsonlFile(join(sfHome, "sessions", sessionKey));
	const activityFile = latestJsonlFile(join(sfDir, "activity"));

	const files: Array<SourceFile | null> = [
		{ source: "notif", path: join(sfDir, "notifications.jsonl") },
		sessionFile ? { source: "session", path: sessionFile } : null,
		activityFile ? { source: "activity", path: activityFile } : null,
		{ source: "audit", path: join(sfDir, "audit-log.jsonl") },
	];

	return files.filter(
		(file): file is SourceFile => file !== null && existsSync(file.path),
	);
}

function readRecentLines(filePath: string, maxBytes = 256 * 1024): string[] {
	let content: string;
	try {
		const stat = statSync(filePath);
		if (stat.size <= maxBytes) {
			content = readFileSync(filePath, "utf-8");
		} else {
			const fd = openSync(filePath, "r");
			try {
				const buffer = Buffer.alloc(maxBytes);
				readSync(fd, buffer, 0, maxBytes, stat.size - maxBytes);
				content = buffer.toString("utf-8");
				const firstNewline = content.indexOf("\n");
				if (firstNewline >= 0) content = content.slice(firstNewline + 1);
			} finally {
				closeSync(fd);
			}
		}
	} catch {
		return [];
	}
	return content.split(/\n/).filter((line) => line.trim().length > 0);
}

function parseTimestamp(value: unknown): string {
	if (typeof value === "number" && Number.isFinite(value)) {
		return new Date(value).toISOString();
	}
	if (typeof value === "string" && value.trim()) {
		const date = new Date(value);
		if (!Number.isNaN(date.getTime())) return date.toISOString();
	}
	return new Date().toISOString();
}

function truncateOneLine(value: string, max = 220): string {
	const compact = value.replace(/\s+/g, " ").trim();
	if (compact.length <= max) return compact;
	return `${compact.slice(0, max - 3)}...`;
}

function textFromContent(content: unknown): string {
	if (typeof content === "string") return content;
	if (!Array.isArray(content)) return "";
	return content
		.filter(
			(block): block is Record<string, unknown> =>
				block && typeof block === "object",
		)
		.filter((block) => block.type === "text" || block.type === "thinking")
		.map((block) => String(block.text ?? block.content ?? ""))
		.filter(Boolean)
		.join(" ");
}

function toolNamesFromContent(content: unknown): string[] {
	if (!Array.isArray(content)) return [];
	return content
		.filter(
			(block): block is Record<string, unknown> =>
				block && typeof block === "object",
		)
		.filter((block) => block.type === "toolCall")
		.map((block) => String(block.name ?? block.toolName ?? ""))
		.filter(Boolean);
}

function summarizeSessionLikeEntry(
	source: LogSourceName,
	entry: Record<string, unknown>,
	filePath: string,
): MergedLogEvent | null {
	const rawMessage = entry.message as Record<string, unknown> | undefined;
	const message =
		rawMessage && typeof rawMessage === "object" ? rawMessage : entry;
	const role = String(message.role ?? "");
	const entryType = String(entry.type ?? "");

	if (entryType === "tool_execution_start") {
		const toolName = String(entry.toolName ?? "tool");
		return {
			source,
			timestamp: parseTimestamp(entry.timestamp ?? entry.ts),
			message: `tool: ${toolName}`,
			filePath,
		};
	}

	if (entryType === "execution_complete") {
		return {
			source,
			timestamp: parseTimestamp(entry.timestamp ?? entry.ts),
			message: `execution complete: ${String(entry.status ?? "completed")}`,
			severity: entry.status === "error" ? "error" : undefined,
			filePath,
		};
	}

	if (entryType === "message_update") {
		const update = entry.assistantMessageEvent as
			| Record<string, unknown>
			| undefined;
		const updateType = String(update?.type ?? "");
		if (updateType === "text_delta" || updateType === "thinking_delta") {
			const delta = String(update?.delta ?? update?.text ?? "");
			if (!delta.trim()) return null;
			return {
				source,
				timestamp: parseTimestamp(entry.timestamp ?? entry.ts),
				message: `assistant: ${truncateOneLine(delta)}`,
				filePath,
			};
		}
		if (updateType === "toolcall_end") {
			const toolCall = update?.toolCall as Record<string, unknown> | undefined;
			const toolName = String(toolCall?.name ?? "tool");
			return {
				source,
				timestamp: parseTimestamp(entry.timestamp ?? entry.ts),
				message: `tool: ${toolName}`,
				filePath,
			};
		}
		return null;
	}

	if (role === "assistant") {
		const tools = toolNamesFromContent(message.content);
		const text = truncateOneLine(textFromContent(message.content));
		const stopReason =
			typeof message.stopReason === "string" ? message.stopReason : undefined;
		const parts: string[] = [];
		if (text) parts.push(`assistant: ${text}`);
		if (tools.length > 0) parts.push(`tools: ${tools.join(", ")}`);
		if (stopReason) parts.push(`stop: ${stopReason}`);
		if (parts.length === 0) return null;
		return {
			source,
			timestamp: parseTimestamp(entry.timestamp ?? message.timestamp),
			message: parts.join(" | "),
			severity: stopReason === "error" ? "error" : undefined,
			filePath,
		};
	}

	if (role === "toolResult") {
		const toolName = String(message.toolName ?? "");
		if (!toolName) return null;
		return {
			source,
			timestamp: parseTimestamp(entry.timestamp ?? message.timestamp),
			message: `tool result: ${toolName}${message.isError === true ? " error" : ""}`,
			severity: message.isError === true ? "error" : undefined,
			filePath,
		};
	}

	return null;
}

export function parseLogLine(
	source: LogSourceName,
	line: string,
	filePath: string,
): MergedLogEvent | null {
	let entry: Record<string, unknown>;
	try {
		entry = JSON.parse(line) as Record<string, unknown>;
	} catch {
		return null;
	}

	if (source === "notif") {
		const message = String(entry.message ?? "");
		if (!message.trim()) return null;
		return {
			source,
			timestamp: parseTimestamp(entry.ts ?? entry.timestamp),
			message: truncateOneLine(message),
			severity: typeof entry.severity === "string" ? entry.severity : undefined,
			filePath,
		};
	}

	if (source === "audit") {
		const component = String(entry.component ?? "audit");
		const message = String(entry.message ?? entry.error ?? "");
		if (!message.trim()) return null;
		return {
			source,
			timestamp: parseTimestamp(entry.ts ?? entry.timestamp),
			message: `[${component}] ${truncateOneLine(message)}`,
			severity: typeof entry.severity === "string" ? entry.severity : "error",
			filePath,
		};
	}

	return summarizeSessionLikeEntry(source, entry, filePath);
}

function matchesFilters(
	event: MergedLogEvent,
	source?: LogSourceName,
	severity?: string,
): boolean {
	if (source && event.source !== source) return false;
	if (
		severity &&
		(event.severity ?? "").toLowerCase() !== severity.toLowerCase()
	)
		return false;
	return true;
}

export function collectRecentLogEvents(
	options: CollectRecentLogOptions,
): MergedLogEvent[] {
	const sfHome = options.sfHome ?? sfHomeFromEnv();
	const files = resolveSourceFiles(options.basePath, sfHome);
	const limit = Math.max(1, options.limit ?? 50);
	const events: MergedLogEvent[] = [];

	for (const file of files) {
		if (options.source && file.source !== options.source) continue;
		for (const line of readRecentLines(file.path)) {
			const event = parseLogLine(file.source, line, file.path);
			if (event && matchesFilters(event, options.source, options.severity)) {
				events.push(event);
			}
		}
	}

	events.sort(
		(a, b) => new Date(a.timestamp).getTime() - new Date(b.timestamp).getTime(),
	);
	return events.slice(-limit);
}

export function formatMergedLogEvent(event: MergedLogEvent): string {
	return `${event.timestamp} [${event.source}] ${event.message}\n`;
}

function parseLogsArgs(argv: string[]): ParsedLogsArgs | null {
	const args = argv.slice(1);
	const sub = args[0];
	if (sub !== "tail" && sub !== "follow") return null;

	const parsed: ParsedLogsArgs = { command: sub };
	for (let i = 1; i < args.length; i++) {
		const arg = args[i];
		if (arg === "--source" && i + 1 < args.length) {
			parsed.source = normalizeSource(args[++i]);
		} else if (arg.startsWith("--source=")) {
			parsed.source = normalizeSource(arg.slice("--source=".length));
		} else if (arg === "--severity" && i + 1 < args.length) {
			parsed.severity = args[++i];
		} else if (arg.startsWith("--severity=")) {
			parsed.severity = arg.slice("--severity=".length);
		}
	}
	return parsed;
}

function usage(): string {
	return (
		[
			"Usage: sf logs tail|follow [--source notif|session|activity|audit] [--severity level]",
			"",
			"Streams notifications, latest session summaries, latest activity log, and audit errors.",
		].join("\n") + "\n"
	);
}

function readFromOffset(
	filePath: string,
	offset: number,
): { lines: string[]; offset: number } {
	try {
		const stat = statSync(filePath);
		const start = stat.size < offset ? 0 : offset;
		const length = stat.size - start;
		if (length <= 0) return { lines: [], offset: stat.size };

		const fd = openSync(filePath, "r");
		try {
			const buffer = Buffer.alloc(length);
			readSync(fd, buffer, 0, length, start);
			return {
				lines: buffer
					.toString("utf-8")
					.split(/\n/)
					.filter((line) => line.trim().length > 0),
				offset: stat.size,
			};
		} finally {
			closeSync(fd);
		}
	} catch {
		return { lines: [], offset };
	}
}

export async function runLogsCli(
	argv: string[],
	options: TailOptions,
): Promise<number> {
	const parsed = parseLogsArgs(argv);
	const stdout = options.stdout ?? process.stdout;
	const stderr = options.stderr ?? process.stderr;
	if (!parsed) {
		stderr.write(usage());
		return 1;
	}
	if (
		parsed.source === undefined &&
		argv.some((arg) => arg.startsWith("--source"))
	) {
		stderr.write("sf logs: unknown --source value\n");
		return 1;
	}

	const source = parsed.source ?? options.source;
	const severity = parsed.severity ?? options.severity;
	const sfHome = options.sfHome ?? sfHomeFromEnv();

	for (const event of collectRecentLogEvents({
		basePath: options.basePath,
		sfHome,
		source,
		severity,
		limit: 50,
	})) {
		stdout.write(formatMergedLogEvent(event));
	}

	const offsets = new Map<string, number>();
	const watched = new Map<string, SourceFile>();

	const refreshWatches = () => {
		for (const file of resolveSourceFiles(options.basePath, sfHome)) {
			if (source && file.source !== source) continue;
			if (watched.has(file.path)) continue;
			watched.set(file.path, file);
			try {
				offsets.set(file.path, statSync(file.path).size);
			} catch {
				offsets.set(file.path, 0);
			}
			watchFile(file.path, { interval: 500 }, () => {
				const currentOffset = offsets.get(file.path) ?? 0;
				const result = readFromOffset(file.path, currentOffset);
				offsets.set(file.path, result.offset);
				for (const line of result.lines) {
					const event = parseLogLine(file.source, line, file.path);
					if (event && matchesFilters(event, source, severity)) {
						stdout.write(formatMergedLogEvent(event));
					}
				}
			});
		}
	};

	refreshWatches();
	const refreshTimer = setInterval(refreshWatches, 1000);

	await new Promise<void>((resolve) => {
		const stop = () => {
			clearInterval(refreshTimer);
			for (const path of watched.keys()) unwatchFile(path);
			process.off("SIGINT", stop);
			process.off("SIGTERM", stop);
			resolve();
		};
		process.on("SIGINT", stop);
		process.on("SIGTERM", stop);
	});

	return 0;
}