/**
 * Copy + Sync — Ctrl+Shift+C shortcut for clipboard sync
 *
 * Registers a keyboard shortcut that:
 * 1. Reads selected text from clipboard (Xvfb/X11 on headless server)
 * 2. Writes to bridge file for terminal paste
 * 3. POSTs to GitHub Gist for cross-device sync
 *
 * Only fires on explicit Ctrl+Shift+C — NOT on auto-select/highlight.
 */

import { execSync } from "node:child_process";
import { existsSync, readFileSync, writeFileSync } from "node:fs";
import { join } from "node:path";
import { homedir } from "node:os";
import { postToGist, isConfigured as isGistConfigured } from "./gist-relay.js";

// ─── Bridge file path ─────────────────────────────────────────────────────────

const BRIDGE_FILE = join(homedir(), ".herdr-clipboard");
const XCLIP_WRAPPER = join(homedir(), ".local", "bin", "xclip");

// ─── Mojibake detection & repair ──────────────────────────────────────────────

/**
 * Detect UTF-8 mojibake (double-encoding: UTF-8 → Latin-1 → UTF-8).
 *
 * The pattern:
 * - UTF-8 box-drawing chars (e2 xx xx) get Latin-1 decoded to "âÄx" chars
 * - When those Latin-1 chars are re-encoded as UTF-8:
 *   - "â" (c3 a2) = UTF-8 Latin small Letter A with Circumflex
 *   - "Ä" (c2 94) = UTF-8 Latin Capital Letter A with Diaeresis
 *   - "Œ" (c2 8c) = UTF-8 Latin Capital Ligature OE
 * - So raw UTF-8 box-drawing chars e2 94 8c become "âÄŒ" (c3 a2 c2 94 c2 8c)
 *   when misdecoded as Latin-1 then re-encoded.
 *
 * Detection heuristic: "â" or "Ã" followed by another non-ASCII char or
 * box-drawing surrogate pairs.  These sequences are almost always mojibake.
 */
function isMojibake(text: string): boolean {
	// "â" = \u00e2, "Ã" = \u00c3 — common Latin-1 surrogates in mojibake
	// Check for these appearing before other non-ASCII chars (box-drawing etc.)
	const moji = /[\u00e2\u00c2\u00e3\u00c3][\u0080-\u00ff]/;
	return moji.test(text);
}

/**
 * Repair UTF-8 mojibake: UTF-8 bytes interpreted as Latin-1 → re-interpret as UTF-8.
 *
 * Safe because:
 * 1. isMojibake() already confirmed the string has the characteristic pattern
 * 2. We only apply Buffer.from(str, "latin1") to the affected substrings
 * 3. Plain ASCII and correctly-encoded UTF-8 pass through unchanged
 *    (Buffer.from("hello", "latin1").toString("utf8") === "hello")
 * 4. Thai/other CJK scripts don't have the "â"+"Ä" surrogate pattern
 *
 * @param text - possibly-mojibaked string
 * @returns repaired UTF-8 string
 */
function repairMojibake(text: string): string {
	if (!isMojibake(text)) return text;

	try {
		// Encode the JavaScript string back to its byte representation using
		// Latin-1 (which is byte-identity for all code points 0-255), then
		// decode those bytes as UTF-8.  This reverses the double-encoding.
		return Buffer.from(text, "latin1").toString("utf8");
	} catch {
		// If encoding fails for any reason, return original
		return text;
	}
}

// ─── Read from Xvfb clipboard ─────────────────────────────────────────────────

function readFromClipboard(): string | null {
	// Try Xvfb xclip first (our headless clipboard)
	try {
		const content = execSync(
			`"${XCLIP_WRAPPER}" -selection clipboard -o 2>/dev/null || DISPLAY=:99 xclip -selection clipboard -o 2>/dev/null || true`,
			{ encoding: "utf8", timeout: 2000 },
		)
			.trim()
			// Repair mojibake that xclip or Xvfb might have introduced
			.replace(/\r\n/g, "\n");

		if (content) return repairMojibake(content);
	} catch {
		// Fall through
	}

	// Fallback: read bridge file directly
	try {
		if (existsSync(BRIDGE_FILE)) {
			const content = readFileSync(BRIDGE_FILE, "utf8").trim();
			if (content) return repairMojibake(content);
		}
	} catch {
		// fall through
	}

	return null;
}

// ─── Write to bridge file ─────────────────────────────────────────────────────

function writeToBridge(text: string): void {
	try {
		// Write raw UTF-8 bytes — no transformation needed.
		// UTF-8 strings in Node.js write correctly with writeFileSync(file, "utf8").
		writeFileSync(BRIDGE_FILE, text, "utf8");
	} catch {
		// ignore
	}
}

// ─── Write to Xvfb clipboard ──────────────────────────────────────────────────

function writeToXvfb(text: string): boolean {
	try {
		// Pass raw bytes via Buffer to avoid any implicit encoding conversion.
		// This ensures UTF-8 multi-byte sequences are sent as-is to xclip.
		execSync(`"${XCLIP_WRAPPER}" -selection clipboard -in`, {
			input: Buffer.from(text, "utf8"),
			timeout: 5000,
		});
		return true;
	} catch {
		return false;
	}
}

// ─── Main: copy + sync ───────────────────────────────────────────────────────

/**
 * Read selected text, write to bridge, sync to Gist.
 * Called by the Ctrl+Shift+C shortcut handler.
 */
export async function copyAndSync(ctx: {
	ui: { notify: (msg: string, type?: string) => void };
}): Promise<void> {
	const text = readFromClipboard();

	if (!text) {
		ctx.ui.notify(
			"No clipboard content. Make sure text is selected in the terminal.",
			"warning",
		);
		return;
	}

	// Write to bridge file (for terminal paste)
	writeToBridge(text);

	// Write to Xvfb clipboard (for Ctrl+Shift+V paste in terminal)
	const xvfbOk = writeToXvfb(text);

	// Sync to GitHub Gist (for cross-device clipboard)
	if (isGistConfigured()) {
		const gistOk = await postToGist(text);
		if (gistOk) {
			ctx.ui.notify(`Synced ${text.length} chars to Gist ✓`, "info");
		} else {
			ctx.ui.notify(
				`Copied ${text.length} chars (Gist sync failed)`,
				"warning",
			);
		}
	} else if (xvfbOk) {
		ctx.ui.notify(`Copied ${text.length} chars to clipboard`, "info");
	} else {
		ctx.ui.notify(
			`Copied ${text.length} chars (terminal paste may not work on headless server)`,
			"warning",
		);
	}
}

// ─── Register shortcut ───────────────────────────────────────────────────────

// eslint-disable-next-line @typescript-eslint/no-explicit-any
type AnyPi = any;

/**
 * Register Ctrl+Shift+C as the copy+sync shortcut.
 * The Key.ctrlShift("c") syntax comes from @earendil-works/pi-tui.
 */
export function registerCopySyncShortcut(pi: AnyPi, Key: AnyPi): void {
	try {
		pi.registerShortcut(Key.ctrlShift("c"), {
			description: "Copy to clipboard + sync to GitHub Gist",
			handler: async (rawCtx: AnyPi) => {
				await copyAndSync(
					rawCtx as { ui: { notify: (msg: string, type?: string) => void } },
				);
			},
		});
	} catch (err) {
		console.error("[copy-sync] Failed to register shortcut:", err);
	}
}